Tolerizing antigen specific immunotherapies

Abstract

Provided are amino acid and nucleic acid sequences that can promote antigen-specific tolerance in a human subject in need thereof. In addition, delivery vehicles comprising such nucleic acids (e.g., mRNAs) are described. Also disclosed are methods of using these agents to control unwanted immune responses and treat disease in a human subject in need thereof.

Description

[0001] Attorney Docket No.: 45817-0174WO1 TOLERIZING ANTIGEN SPECIFIC IMMUNOTHERAPIES CROSS-REFERENCE TO RELATED APPLICATION This application claims the benefit of priority of U.S. Provisional Application No. 63 / 567,297 filed March 19, 2024, the contents of which are incorporated by reference herein in their entirety. SEQUENCE LISTING The instant application contains a Sequence Listing which has been submitted electronically in XML format and is hereby incorporated by reference in its entirety. Said XML copy, created on March 14, 2025, is named 45817- 0174WO1_SL.xml and is 212,809 bytes in size. BACKGROUND The development of new approaches to control unwanted immune responses is needed for the management of diseases such as autoimmunity, autoinflammatory diseases, allergies, and protein replacement therapies, where the uncontrolled immune responses to self or non-harmful antigens severely affects the physiological function of tissues and organs. Current treatments for such conditions involve the use of non-specific immunosuppressants and supportive therapies that often require lifelong treatments and have significant side effects. Thus, the ability to selectively control antigen-specific or tissue-specific immune responses and promote or restore tolerance is urgently required. SUMMARY The present disclosure provides, inter alia, a fusion polypeptide which induces tolerance in a human subject to a selected protein or proteins, wherein the fusion polypeptide comprises a first amino acid sequence which comprises at least one T cell epitope derived from the selected protein or proteins fused directly or via a linker to an endolysosomal targeting sequence. Apart from targeting the first amino acid sequence to Attorney Docket No.: 45817-0174WO1 the endolysosomal compartment, the endolysosomal targeting sequence avoids cell surface display or secretion of the antigen for tolerization that could lead to undesirable antibody mediated effector functions in patients (e.g., autoimmune patients) with pre- existing antibody responses. In some cases, the endolysosomal targeting sequence is not a sequence that causes non-specific CD8+ T cell activation. In some cases, the endolysosomal targeting sequence is not a sequence from human MITD (e.g., does not comprise SEQ ID NO:29). In some cases, the fusion polypeptide comprises a signal sequence. In certain cases, the first amino acid sequence comprises a total of two to six, three to six, four to six, three, four, five, or six T cell epitopes derived from the selected protein or proteins, wherein the T cell epitopes are linked together (e.g., via peptide linker). In some instances, the selected protein or proteins is one of E2 component of mitochondrial pyruvate dehydrogenase complex (PDC-E2), another pyruvate complex protein such as E3 binding protein (E3BP), 2-oxo-glutarate dehydrogenase complex (OGDC-E2), the branched-chain 2-oxoacid dehydrogenase complex (BCOADC-E2), or the E1a component of mitochondrial pyruvate dehydrogenase complex (PDC-E1a), myelin oligodendrocyte glycoprotein (MOG), gliadin, or transglutaminase. In another instance, the selected protein or proteins is one of myelin basic protein (MBP), myelin proteolipid protein PLP or lipophilin, aquaporin, proinsulin, glutamic acid carboxylase, recombinant Factor VIII, Sp100, Nuclear pore glycoprotein 210 (gp210), Neuronal nicotinic acetylcholine receptor (nAChR), Muscle-specific Kinase (MuSK), Low-density lipoprotein receptor-related protein 4 (LRP-4), Agrin, Thyroid stimulating hormone receptor, Aquaporin-4 (AQP4), noncollagenous-1 (NC1) domain of type IV collagen in the glomerular basement membrane (GBM), Desmosomal adhesion proteins, desmoglein (Dsg)1 or Dsg3, proinsulin, insulin, glutamic acid decarboxylase, islet antigen -2, or Zinc Transporter 8, myosin heavy chain alpha, 21-hydroxylase, Thyroglobulin, thyroid peroxidase, tyrotropin receptor, sodium iodide symporter, intrinsic factor (IF) or H+ / K+- ATPase, a component of the platelet membrane glycoprotein (GP) complex, GM-CSF, HLA B27 associated antigen, a pancreatic autoantibody or Glycoprotein 2, integrin αvβ6, Attorney Docket No.: 45817-0174WO1 Cathelicidin LL-37, melanocytic ADAMTSL5, lipid antigen PLA2G4D, or keratin 17, Melanocyte antigen, Myelin antigen, a histone H1, H3, H4, Rheumatoid Factor that recognize Fc-tail of immunoglobulin (Ig)-Gs, multiple citrullinated-antigen, SSA / Ro, SSB / La, ANA, M3R, VIPR, or platelet-selectin. In some instances, the selected protein or proteins is an autoantigen, a foreign antigen, an allergen, a protein therapeutic, or a protein that the host immune system considers foreign during therapeutic replacement or transplantation. In some cases, the first amino acid sequence comprises or consists of a single T cell epitope, a string of T cell epitopes, a shuffled T cell epitope, a subunit of an antigen, a partial antigen sequence, or a full antigen sequence. In some cases, the first amino acid sequence comprises a string of T cell epitopes of the selected protein or proteins covalently linked in a sequence not present in the naturally occurring version of the selected protein or proteins, optionally wherein the string of T cell epitopes is linker by a peptide linker. In one case, the peptide linker comprises or consists of the sequence of SEQ ID NO: 168. In certain instances, the first amino acid sequence comprises a T cell epitope of PDC-E2 and comprises or consists of an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to one or more of : (i) amino acids 163-176 of the human PDC-E2 protein (SEQ ID NO:175); (ii) amino acids 36-49 of the human PDC-E2 protein (SEQ ID NO: 173); or (iii) amino acids 425- 444 of the human PDC-E2 protein (SEQ ID NO:171). In certain instances, the first amino acid sequence comprises a T cell epitope of E3BP and comprises or consists of an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to amino acids 34- 47 of the human E3BP protein (SEQ ID NO: 172). In certain instances, the first amino acid sequence comprises a T cell epitope of OGDC-E2 and comprises or consists of an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least Attorney Docket No.: 45817-0174WO1 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to amino acids 100-113 of the human OGDC-E2 protein (SEQ ID NO: 176). In certain instances, the first amino acid sequence comprises a T cell epitope of BCOADC-E2 and comprises or consists of an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to amino acids 90-103 of the human BCOADC-E2 protein (SEQ ID NO: 174). In certain cases, if more than one (e.g., 1, 2, 3, 4) antigen associated with a particular disease (e.g., PBC) is employed as the selected proteins, then the T cell epitopes of these antigens are linked by a linker such as an RRKR (SEQ ID NO: 168) linker. In one instance, the first amino acid sequence comprises one or more (e.g., 1, 2, 3, 4, 5, 6) of the amino acid sequences of PDC-E2163-176, PDC-E236-49, PDC-E2425-444, E3BP34-47, OGDC-E2100-113,and BCOADC-E290-103. In some cases, all six of these amino acid sequences are present in the antigen for tolerization. In certain cases, these amino acids sequences are linked by a peptide linker such as an RRKR (SEQ ID NO: 168) linker. In one instance the first amino acid sequence comprises a sequence from N to C- terminal as follows: a signal peptide (e.g., SEQ ID NO:170) fused to PDC-E2425-444(SEQ ID NO: 171)linked via a peptide linker (e.g., SEQ ID NO:168) to E3BP 34-47 (SEQ ID NO: 172) linked via a peptide linker (e.g., SEQ ID NO:168) to PDC-E236-49 (SEQ ID NO: 173) linked via a peptide linker (e.g., SEQ ID NO:168) to BCOADC-E290-103(SEQ ID NO: 174) linked via a peptide linker (e.g., SEQ ID NO:168) to PDC-E2163-176 (SEQ ID NO: 175) linked via a peptide linker (e.g., SEQ ID NO:168) to OGDC-E2100-113 (SEQ ID NO: 176). In some cases, the C-terminus of the first amino acid sequence also includes a peptide linker (e.g., SEQ ID NO:168). In some instances, the first amino acid sequence comprises a sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence: Attorney Docket No.: 45817-0174WO1 ISNIRRVIAQRLMQSKQTIPRRKRGDALCEIETDKAVVRRKRGDLIAEVETDKATV RRKRFDSICEVQSDKASVRRKRGDLLAEIETDKATIRRKRDEVVKEIETDKTSV (SEQ ID NO: 169). It is to be understood that the linkers (SEQ ID NO:168) in SEQ ID NO:169 can be replaced with another linker or linkers (e.g., glycine serine linkers). In certain instances, the N-terminal of SEQ ID NO:169 comprises a signal sequence (e.g., MLVMAPRTVLLLLSAALALTETWA (SEQ ID NO: 170)). In other instances, the C- terminal of SEQ ID NO:169 comprises a linker (e.g., the sequence set forth in SEQ ID NO: 168)). In some instances, the selected protein or proteins is / are antigens associated with PBC such as PDC-E2, E3BP, BCOADC-E2, and / or OGDC-E2. In some cases, The T cell epitopes from these proteins include one or more (1, 2, 3, 4, 5, 6) of SEQ ID NOs.: 171 to 176. In certain cases, the first amino acid sequence comprises or consists of an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to SEQ ID NO:169. In some instances, the selected protein is MOG and comprises or consists of an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to : (i) amino acids 35-55 of the human MOG protein; (ii) amino acids 27-63 of the human MOG protein; or (iii) amino acids 1-125 of the human MOG protein. In certain instances, the endolysosomal targeting sequence comprises a Y-X-X-φ sequence (wherein X is any amino acid and φ is any hydrophobic amino acid) from human LAMP1, human LAMP2, or human DC-LAMP. In other cases, the endolysosomal targeting sequence comprises a sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to amino acids 1-80 of human CD74 (invariant chain). In some cases, the endolysosomal targeting sequence is Attorney Docket No.: 45817-0174WO1 a human invariant chain polypeptide and comprises or consists of an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO:32. In certain cases, the endolysosomal targeting sequence is a human invariant chain polypeptide and comprises or consists of an amino acid sequence of SEQ ID NO:32 with 1, 2, 3, 4, 5, 6, 7, 8, or 9 amino acid substitutions. In some cases, the endolysosomal targeting sequence comprises or consists of a fragment or subunit of human CD74. In some instances, the endolysosomal targeting sequence is a human LAMP1 polypeptide or a fragment or subunit thereof. In certain cases, the human LAMP1 polypeptide comprises or consists of an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO:30. In some cases, the human LAMP1 polypeptide comprises or consists of an amino acid sequence of SEQ ID NO: 30 with 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 amino acid substitutions. In certain cases, the human LAMP1 polypeptide comprises or consists of an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO:31. In other cases, the human LAMP1 polypeptide comprises or consists of an amino acid sequence of SEQ ID NO: 31 with 1, 2, or 3 amino acid substitutions. In some cases, the endolysosomal targeting sequence comprises or consists of a fragment or subunit of human LAMP1, human LAMP2, or human DC-LAMP. In certain instances, the first amino acid sequence is fused directly to the endolysosomal targeting sequence. In other cases, the first amino acid sequence is fused to the endolysosomal targeting sequence via a linker. In some cases, the linker is a peptide linker. The peptide linker can be a Glycine Serine linker. In some cases, the linker is G4S (SEQ ID NO: 141) or (G4S)n, where n = 2, 3, 4, 5, 6, 7, 8, 9, or 10 (SEQ Attorney Docket No.: 45817-0174WO1 ID NO: 142). In other cases, the linker comprises or consists of the sequence of SEQ ID NO: 168. In some instances, the endolysosomal targeting sequence is positioned at or fused to the C-terminus of the first amino acid sequence. In other cases, the endolysosomal targeting sequence is positioned at or fused to the N-terminus of the first amino acid sequence. For example, in certain instances, where the endolysosomal targeting sequence is human CD74, the endolysosomal targeting sequence is positioned at or fused to the N- terminus of the first amino acid sequence. In some instances, the fusion polypeptide comprises an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence set forth in SEQ ID NO: 169, 177, or 166. It is to be understood that the signal peptide and / or linkers in SEQ ID NO:166 can be replaced with another signal peptide and / or linker. In some instances, the fusion polypeptide comprises an amino acid sequence set forth in SEQ ID NO: 169, 177, or 166 with 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 amino acid substitutions. In certain instances, the fusion polypeptide further comprises a Treg epitope. In some cases, the Treg epitope comprises an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, at least 99%, or 100% identical to the sequence set forth in any one of SEQ ID NOs: 213-220 or 43-48. In other cases, the Treg epitope comprises an amino acid sequence set forth in any one of SEQ ID NOs: 213-220 or 43-48 with 1, 2, 3, or 4 amino acid substitutions. The Treg epitope may be fused at the N or C-terminus of the fusion polypeptide. In some cases, the Treg epitope may be positioned between the antigen for tolerization and the endolysosomal targeting sequence. In some cases, the Treg epitope is not fused to the fusion polypeptide but is present in a composition with the fusion polypeptide. In some instances, the fusion polypeptide is administered together with an immunomodulator. This is particularly beneficial in instances where the antigen against Attorney Docket No.: 45817-0174WO1 which tolerance is desired has not undergone central tolerance and can be useful for peripheral induction of Tregs, suppression of effector T cell activation to drive anergy / non-responsiveness or deletion, or for enhancing Treg suppressive functionality with alternative routes of administration (e.g., intradermal, subcutaneous, or intramuscular routes of administration). In certain cases, the immunomodulator is a Treg epitope such as one listed in Table 2. The Treg epitope can be fused to the fusion polypeptide (e.g., at N or C terminus of the fusion polypeptide). In some cases, the disclosure features an mRNA encoding a Treg epitope fused to a fusion polypeptide described herein. In some cases, all the uracils of the mRNA are N1-methylpseudouracil. In some cases, the immunomodulator is an IL2 mutein. The IL2 mutein may be fused to HSA or a human IgG Fc region (e.g., IgG1 hinge +CH2 +CH3), In some cases, the IL2 mutein comprises an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the sequence of SEQ ID NO:158 or 156. In other cases, the IL2 mutein comprises an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the sequence of SEQ ID NO:158 or 156. In some instances, the immunomodulator is an inhibitor of mTOR (e.g., MORG1, PRAS40, DEPTOR). In some cases, the mTOR inhibitor comprises an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the sequence of SEQ ID NO: 160, 162, or 164. In some instances, the immunomodulator is an activator of TGFβ (such as ITB6 or ITB8). See, e.g., PCT / US2022 / 79095 (incorporated by reference in its entirety herein). In some instances, the immunomodulator is an NFĸB inhibitor or a PI3K / AKT inhibitor. Attorney Docket No.: 45817-0174WO1 In certain instances, the immunomodulator is an mRNA encoding an IL2 mutein, an mTOR inhibitor, an activator of TGFβ, an NFĸB inhibitor, or a PI3K / AKT inhibitor. In certain cases, the immunomodulator is encoded by an mRNA that encodes an amino acid sequence that comprises a sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to a sequence set forth in any one of SEQ ID NOs.: 156, 158, 160, 162, 164, 182, or 185. In other cases, the immunomodulator is encoded by an mRNA that comprises a nucleotide sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to a sequence set forth in any one of SEQ ID NOs.: 157, 159, 161, 163, 181, or 184. The mRNA may be coformulated in the same delivery vehicle (e.g., LNP) comprising an mRNA encoding the fusion polypeptide described herein or can be in a separate delivery vehicle. In some cases, the LNP is LNP1, LNP A, LNPB, LNP C, LNP D, or LNP E. In certain cases, all the uracils of the mRNA or mRNAs are N1-methylpseudouracil. In some instances, the disclosure encompasses pharmaceutical compositions comprising a fusion polypeptide described herein and one or more immunomodulators such as an IL-2 mutein described herein, an activator of TGFβ (such as ITB6 or ITB8), an inhibitor of mTOR (such as MORG1, PRAS40, DEPTOR), an NFĸB inhibitor, or a PI3K / AKT inhibitor. In some cases, the combination comprises a fusion polypeptide described herein and an immunomodulator that is one or more of: (i) an IL2 mutein comprising an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence set forth in SEQ ID NO:158 or SEQ ID NO:156; and / or (ii) an inhibitor of mTOR comprising an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence set forth in any one of SEQ ID NO:160, 162, or 164; and / or (iii) an ITB6 described in PCT / US2022 / 79095. Attorney Docket No.: 45817-0174WO1 In another aspect, the disclosure features a polynucleotide encoding a fusion polypeptide of the disclosure. In yet another aspect, the disclosure features a polynucleotide encoding an IL-2 mutein. In another aspect, the disclosure features a polynucleotide encoding an activator of TGFβ (such as ITB6 or ITB8). In some aspects, the disclosure features a polynucleotide encoding an inhibitor of mTOR. In yet another aspect, the disclosure features a polynucleotide encoding an NFĸB inhibitor. In yet another aspect, the disclosure features a polynucleotide encoding PI3K / AKT inhibitor. In some cases, the disclosure encompasses compositions comprising combinations of these polynucleotides. In another aspect, the disclosure provides a vector comprising a polynucleotide encoding a fusion polypeptide of the disclosure. In another aspect, the disclosure provides a vector comprising a polynucleotide encoding an immunomodulator of the disclosure. In yet another aspect, the disclosure relates to a host cell comprising a polynucleotide(s) or vector(s) of the disclosure. In a further aspect, the disclosure provides a method of making a fusion polypeptide of the disclosure. The method comprises culturing the host cell described above under conditions that promote the production of the fusion polypeptide and isolating the fusion polypeptide. In some cases, the method further involves formulating the fusion polypeptide as a sterile pharmaceutical composition. In a different aspect, the disclosure features a polynucleotide comprising a messenger RNA (mRNA) comprising an open reading frame (ORF) encoding a fusion polypeptide of the disclosure. In some instances, encompassed herein is a second mRNA that encodes an IL2 mutein described herein, an inhibitor of mTOR (e.g., MORG1, PRAS40, DEPTOR), an activator of TGFβ (such as ITB6, ITB8), an NFĸB inhibitor, or a PI3K / AKT inhibitor. In some instances, a composition is featured that comprises a first mRNA encoding a fusion polypeptide described herein and a second mRNA that encodes an IL2 mutein described herein, an inhibitor of mTOR (e.g., MORG1, PRAS40, DEPTOR), an activator of TGFβ (such as ITB6, ITB8), an NFĸB inhibitor, or a PI3K / AKT inhibitor. Attorney Docket No.: 45817-0174WO1 In some instances, the ORF comprises a nucleic acid sequence that encodes an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the fusion from N- to C-terminus of the amino acid sequences set forth in (i) SEQ ID NOs: 169 and 30; or (ii) SEQ ID NOs: 169 and 31. In certain cases, the ORF includes a signal peptide encoding sequence immediately N-terminal to SEQ ID NO:169. In some instances, the ORF comprises a nucleic acid sequence that encodes an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence set forth in any one of SEQ ID NOs.: 169, 170, or 166. In certain instances, the ORF is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the nucleic acid sequence set forth in SEQ ID NO: 165. In certain instances, the ORF does not include the N-terminal 72 nucleotides of SEQ ID NO:165. In some instances, the ORF is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to nucleotides 73-531 of SEQ ID NO:165. In some instances, the ORF is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the nucleic acid sequence set forth in SEQ ID NO: 25. In certain instances, the ORF does not include the N-terminal 75 nucleotides of SEQ ID NO:25. In other instances, the ORF is a nucleic acid sequence that encodes an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the fusion from N- to C-terminus of the amino Attorney Docket No.: 45817-0174WO1 acid sequences set forth in (i) SEQ ID NOs: 35 and 30; (ii) SEQ ID NOs: 34 and 30; (iii) SEQ ID NOs: 35 and 31; or (iv) SEQ ID NOs: 34 and 31. In certain instances, the mRNA or mRNAs further comprise a 5’ untranslated region (UTR) comprising the nucleic acid sequence of SEQ ID NO:15 or SEQ ID NO:8. In some instances, the mRNA or mRNAs further comprise a 3’ UTR comprising the nucleic acid sequence of SEQ ID NO:16, SEQ ID NO:9, or SEQ ID NO:167. In certain instances, the mRNA or mRNAs further comprise a 5’ terminal cap. In one instance, the 5’ terminal cap comprises or consists of m7G-ppp-Gm. In some cases, the 5′ terminal cap comprises a m7GpppG2^OMe, m7G-ppp-Gm-A, m7G-ppp-Gm-AG, Cap0, Cap1, ARCA, inosine, N1-methyl-guanosine, 2′-fluoro-guanosine, 7-deaza- guanosine, 8-oxo-guanosine, 2-amino-guanosine, LNA-guanosine, 2-azidoguanosine, Cap2, Cap4, 5′ methylG cap, or an analog thereof. In some instances, the mRNA or mRNAs further comprise poly A region. In some cases, the poly A region is at least about 10, at least about 20, at least about 30, at least about 40, at least about 50, at least about 60, at least about 70, at least about 80, at least about 90 nucleotides in length, or at least about 100 nucleotides in length. In one instance, the poly A region is at least about 100 or 100 nucleotides in length. In certain instances, the mRNA or mRNAs comprise at least one chemically modified nucleobase, sugar, backbone, or any combination thereof. In some cases, the at least one chemically modified nucleobase is selected from the group consisting of pseudouracil (ψ), N1-methylpseudouracil (m1ψ), 1-ethylpseudouracil, 2-thiouracil (s2U), 4’-thiouracil, 5-methylcytosine, 5-methyluracil, 5-methoxyuracil, and any combination thereof. In certain cases, all uracils in the polynucleotide are N1-methylpseudouracils. In some instances, all of the uracils of the mRNA or mRNAs are N1-methylpseudouracils. In some instances, all of the uracils of the mRNA or mRNAs are 5-methoxyuracils. In some instances, the mRNA or mRNAs comprise one or more of: a 5’ untranslated region (UTR) comprising the nucleic acid sequence of SEQ ID NO:15 or SEQ ID NO:8; a 3’ UTR comprising the nucleic acid sequence of SEQ ID NO:16, SEQ ID NO:9, or SEQ ID NO:167; a 5’ terminal cap that comprises or consists of m7G-ppp- Attorney Docket No.: 45817-0174WO1 Gm; and a poly A region is at least about 100 or 100 nucleotides in length. In certain cases, all uracils in the mRNA or mRNAs re N1-methylpseudouracils. In another aspect, the disclosure features a combination comprising an mRNA encoding a fusion polypeptide of the disclosure, and a second mRNA encoding an immunomodulatory agent. In some cases, the immunomodulatory agent is an IL2 mutein. The IL2 mutein may be fused to a half-life extending moiety such as HSA, a VHH that binds HSA, or a human Ig Fc region (e.g., human IgG1 hinge + CH2 + CH3). In other cases, the immunomodulatory agent is a Treg epitope. In yet other cases, the immunomodulatory agent is an inhibitor of mTOR (e.g., MORG1, PRAS40, DEPTOR). In yet other cases, the immunomodulatory agent is an activator of TGFβ such as ITB6 or ITB8. In some cases, a small molecule inhibitor of mTOR is included for administration along with an mRNA encoding a fusion polypeptide of the disclosure (or a delivery vehicle comprising the mRNA). In some cases, the immunomodulatory agent is an NFĸB inhibitor or a PI3K / AKT inhibitor. In another aspect, the disclosure provides a polynucleotide comprising a messenger RNA (mRNA) comprising: (i) a 5′ UTR (e.g., SEQ ID NO: 15); (ii) an open reading frame (ORF) wherein the ORF encodes a protein comprising a sequence that has at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the sequence of any one of SEQ ID NOs: 169, 177, or 166; (iii) a stop codon (assuming a stop codon is not present at the C-terminus of the ORF or at the N-terminus of the 3’UTR); and (iv) a 3′ UTR (e.g., SEQ ID NO: 167). In some cases, all of the uracils of the mRNA are N1-methylpseudouracils. In yet another aspect, the disclosure provides a polynucleotide comprising a messenger RNA (mRNA) comprising: (i) a 5′ UTR (e.g., SEQ ID NO: 15); (ii) an open reading frame (ORF) wherein the ORF comprises a sequence that has at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the sequence of SEQ ID NOs: 165; (iii) a stop codon (assuming a stop codon is not present at the C- Attorney Docket No.: 45817-0174WO1 terminus of the ORF or at the N-terminus of the 3’UTR); and (iv) a 3′ UTR (e.g., SEQ ID NO: 167). In some cases, all of the uracils of the mRNA are N1-methylpseudouracils. In another aspect, the disclosure provides a polynucleotide comprising a messenger RNA (mRNA) comprising: (i) a 5′ UTR; (ii) an open reading frame (ORF) encoding a fusion polypeptide comprising one or more of a human PDC-E2, E3BP, OGDC-E2, BCOADC-E2, or PDC-E1a, or a subunit or fragment or epitope(s) of any of these antigens, which is fused at its C-terminus to a human LAMP1351-389 ; (iii) a stop codon (assuming a stop codon is not present at the N-terminus of the 3’UTR); and (iv) a 3′ UTR. In some cases, all of the uracils of the mRNA are N1-methylpseudouracils. In one aspect, the disclosure provides a polynucleotide comprising a messenger RNA (mRNA) comprising: (i) a 5′ UTR (e.g., SEQ ID NO: 15); (ii) an open reading frame (ORF) encoding a fusion polypeptide comprising one or more of a human PDC- E2425-444, E3BP34-47, PDC-E236-49, BCOADC-E290-103, OGDC-E2100-113 or substitutions variants thereof (i.e., having 1 to 3 substitutions in one or more of these five), which is fused at its C-terminus to a human LAMP1351-389; (iii) a stop codon (assuming a stop codon is not present at the N-terminus of the 3’UTR); and (iv) a 3′ UTR (e.g., SEQ ID NO: 167). In some cases, all of the uracils of the mRNA are N1-methylpseudouracils. In another aspect, the disclosure provides a polynucleotide comprising a messenger RNA (mRNA) comprising: (i) a 5′ UTR (e.g., SEQ ID NO: 15); (ii) an open reading frame (ORF) encoding a fusion polypeptide comprising in order from N-to C- terminus a human PDC-E2425-444, linked via a linker to E3BP34-47linked via a linker to PDC-E236-49 linked via a linker to BCOADC-E290-103 linked via a linker to OGDC-E2 100-113, or substitutions variants thereof (i.e., having 1 to 3 substitutions in one or more of these five), which is fused at its C-terminus to a human LAMP1351-389; (iii) a stop codon (assuming a stop codon is not present at the N-terminus of the 3’UTR); and (iv) a 3′ UTR (e.g., SEQ ID NO: 167). In one instance the linker comprises or consists of the sequence of SEQ ID NO:168. In some cases, all of the uracils of the mRNA are N1- methylpseudouracils. Attorney Docket No.: 45817-0174WO1 In yet another aspect, the disclosure provides a polynucleotide comprising a messenger RNA (mRNA) comprising: (i) a 5′ UTR (e.g., SEQ ID NO: 15); (ii) an open reading frame (ORF) encoding a fusion polypeptide comprising an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO: 166; (iii) a stop codon (assuming a stop codon is not present at the N-terminus of the 3’UTR); and (iv) a 3′ UTR (e.g., SEQ ID NO: 167). In some cases, all of the uracils of the mRNA are N1-methylpseudouracils. In another aspect, the disclosure provides a polynucleotide comprising a messenger RNA (mRNA) comprising: (i) a 5′ UTR (e.g., SEQ ID NO: 15); (ii) an open reading frame (ORF) comprising a nucleic acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO: 165; (iii) a stop codon (assuming a stop codon is not present at the N-terminus of the 3’UTR); and (iv) a 3′ UTR (e.g., SEQ ID NO: 167). In another aspect, the disclosure provides a polynucleotide comprising a messenger RNA (mRNA) comprising: (i) a 5′ UTR; (ii) an open reading frame (ORF) encoding a human MOG1-125human LAMP1351-389fusion polypeptide, wherein the ORF has at least 90% sequence identity to the nucleic acid sequence of SEQ ID NO:3; (iii) a stop codon (assuming a stop codon is not present at the N-terminus of the 3’UTR); and (iv) a 3′ UTR. In another aspect, the disclosure provides a polynucleotide comprising a messenger RNA (mRNA) comprising: (i) a 5′ UTR; (ii) an open reading frame (ORF) encoding a fusion polypeptide comprising a human gliadin, or a subunit or fragment or epitope(s) thereof, which is fused at its C-terminus to a human LAMP1351-389; (iii) a stop codon (assuming a stop codon is not present at the N-terminus of the 3’UTR); and (iv) a 3′ UTR. In another aspect, the disclosure provides a polynucleotide comprising a messenger RNA (mRNA) comprising: (i) a 5′ UTR; (ii) an open reading frame (ORF) Attorney Docket No.: 45817-0174WO1 encoding a fusion polypeptide comprising a human transglutaminase, or a subunit or fragment or epitope(s) thereof, which is fused at its C-terminus to a human LAMP1351-389; (iii) a stop codon (assuming a stop codon is not present at the N-terminus of the 3’UTR); and (iv) a 3′ UTR. In all of the above aspects, it is to be understood that the human LAMP1351-389sequence in these constructs can be replaced by human LAMP2 or a fragment thereof, human DC-LAMP or a fragment thereof, or human CD74 or a fragment thereof. If human CD74 is part of the fusion, then it is generally located N-terminal to the antigen for tolerization. In some instances, the mRNA comprises a 5' terminal cap. In one instance, the 5’ terminal cap comprises or consists of m7G-ppp-Gm. In some cases, the 5' terminal cap comprises a Cap0, Cap1, ARCA, inosine, N1-methyl-guanosine, 2′-fluoro-guanosine, 7- deaza-guanosine, 8-oxo-guanosine, 2-amino-guanosine, LNA-guanosine, 2- azidoguanosine, Cap2, Cap4, 5' methylG cap, or an analog thereof. In some instances, the mRNA further comprises a poly A region. In some cases, the poly A region has about 10 to about 200, about 20 to about 180, about 50 to about 160, about 70 to about 140, or about 80 to about 120 nucleotides in length. In certain cases, the poly A region about 100 nucleotides in length. In certain instances, the mRNA comprises at least one chemically modified nucleobase, sugar, backbone, or any combination thereof. In some cases, the at least one chemically modified nucleobase is selected from the group consisting of pseudouracil (ψ), N1-methylpseudouracil (m1ψ), 1-ethylpseudouracil, 2-thiouracil (s2U), 4’-thiouracil, 5-methylcytosine, 5-methyluracil, 5-methoxyuracil, and any combination thereof. In certain cases, all uracils in the polynucleotide are N1-methylpseudouracils. In another aspect, the disclosure provides a combination comprising the polynucleotide of any one of the above aspects, and a second polynucleotide comprising an mRNA encoding an immunomodulatory agent. In some cases, the immunomodulatory agent is an IL2 mutein or a Treg epitope. The IL2 mutein may be linked to a half-life extending agent (e.g., HSA, a VHH that specifically binds to HSA, a human Ig Fc Attorney Docket No.: 45817-0174WO1 region). In yet other cases, the immunomodulatory agent is an inhibitor of mTOR (e.g., MORG1, PRAS40, DEPTOR). In some cases, a small molecule inhibitor of mTOR is included along with an mRNA encoding a fusion polypeptide of the disclosure. In some cases, the immunomodulatory agent is an activator of TGFβ (e.g., ITB6, ITB8), an NFĸB inhibitor, or a PI3K / AKT inhibitor. In one instance, the disclosure features a combination comprising a polynucleotide comprising a mRNA encoding a fusion polypeptide described herein and a second polynucleotide comprising a second mRNA comprising: (i) a 5′ UTR, optionally comprising or consisting of the sequence of SEQ ID NO:15; (ii) an open reading frame (ORF) comprising a nucleotide sequence that encodes an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of any one of SEQ ID NOs: 213-220, 43-48, 156, 158, 160, 162, or 164; (iii) a stop codon if not present at the C-terminal end of (ii) or at the N-terminus of 3’-UTR; and (iv) a 3′ UTR, optionally comprising or consisting of the sequence of SEQ ID NO:167. In some cases, all of the uracils of the mRNA are N1- methylpseudouracils. In some cases, the mRNA and the second mRNA comprise one or more of: (i) a 5' terminal cap, optionally wherein the 5' terminal cap comprises m7G-ppp- Gm, a Cap0, Cap1, ARCA, inosine, N1-methyl-guanosine, 2′-fluoro-guanosine, 7-deaza- guanosine, 8-oxo-guanosine, 2-amino-guanosine, LNA-guanosine, 2-azidoguanosine, Cap2, Cap4, 5' methylG cap, or an analog thereof; (ii) a poly A region, optionally wherein the poly A region has about 10 to about 200, about 20 to about 180, about 50 to about 160, about 70 to about 140, or about 80 to about 120 nucleotides in length, further optionally wherein the poly A region is 100 nucleotides in length; and / or (iii) at least one chemically modified nucleobase, sugar, backbone, or any combination thereof, optionally wherein the at least one chemically modified nucleobase is selected from the group consisting of pseudouracil (ψ), N1-methylpseudouracil (m1ψ), Attorney Docket No.: 45817-0174WO1 1-ethylpseudouracil, 2-thiouracil (s2U), 4’-thiouracil, 5-methylcytosine, 5-methyluracil, 5-methoxyuracil, and any combination thereof. In one case, and the second mRNA comprise the 5' terminal cap comprising m7G-ppp-Gm, a poly A region, of about 100 nucleotides in length; and all the uracils of the mRNA and second mRNA are N1- methylpseudouracil (m1ψ). In another aspect, the disclosure features a pharmaceutical composition comprising a fusion polypeptide described herein, a polynucleotide described herein, an mRNA or mRNAs described herein, or a combination described herein, and a pharmaceutically acceptable excipient. In yet another aspect, the disclosure relates to a delivery vehicle (e.g., a nanoparticle such as a lipid nanoparticle) comprising an mRNA or mRNAs described herein, a polynucleotide or polynucleotides described herein, or a combination described herein. In one instance, the LNP is a four component LNP comprising an ionizable amino lipid, a phospholipid, a structural lipid (e.g., cholesterol), and a polyethylene glycol (PEG)-modified lipid. In some instances, the ionizable amino lipid that is heptadecan-9- yl 8-((2-hydroxyethyl)(8-(nonyloxy)-8-oxooctyl)amino)octanoate referred to herein as Compound I-18 or a salt thereof. In some cases, the ionizable amino lipid is Compound II-6 or a salt thereof. In certain cases, the phospholipid is DSPC. In some cases, the structural lipid is cholesterol. In some cases, the PEG-lipid is PL-02 or PEG-DMG. Examples of LNPs that can be used are LNP1 and LNP2. In one instance LNP1 is employed as the delivery vehicle. LNP1 comprises Compound I-18 (47 mole ratio%), PL-02 (3 mole ratio%), DSPC (11 mole ratio%), and cholesterol (39 mole ratio%). LNP2 comprises Compound I-18 (48 mole ratio%), PEG-DMG (1.5 mole ratio%), DSPC (11 mole ratio%), and cholesterol (39.5 mole ratio%). In some instances, the lipid nanoparticle is a five component LNP comprising a sialic acid lipid, an ionizable amino lipid, a structural lipid (e.g., cholesterol), a phospholipid, and a polyethylene glycol (PEG)-modified lipid. In some cases, the sialic acid lipid is DSPE-PEG2k-6’-siallylactose depicted as SA-V in this disclosure. In other Attorney Docket No.: 45817-0174WO1 instances, the sialic acid lipid is DSPE-PEG2k-3’-siallylactose depicted as SA-VI in this disclosure. In certain cases, the sialic acid lipid is Compound 1 or a salt thereof or Compound 9 or a salt thereof (wherein Compounds 1 and 9 are depicted in Table SA-1). In some instances, the ionizable amino lipid that is heptadecan-9-yl 8-((2- hydroxyethyl)(8-(nonyloxy)-8-oxooctyl)amino)octanoate referred to herein as Compound I-18 or a salt thereof. In some cases, the ionizable amino lipid is Compound II-6 or a salt thereof. In certain cases, the phospholipid is DSPC. In some cases, the structural lipid is cholesterol. In some cases, the PEG-lipid is PL-02. In some cases, the sialic acid lipid is present in the LNP at about 1 mole ratio%; the ionizable lipid at about 47 mole ratio%; the PEG-lipid at about 2 mole ratio%; the phospholipid at about 11 mole ratio%; and the structural lipid at about 39 mole ratio%. In other cases, the sialic acid lipid is present in the LNP at about 0.5 mole ratio%; the ionizable lipid at about 47 mole ratio%; the PEG- lipid at about 2.5 mole ratio%; the phospholipid at about 11 mole ratio%; and the structural lipid at about 39 mole ratio%. Examples of LNPs that can be used as delivery vehicles are LNP A, LNP B, LNP C, LNP D, or LNP E as described in more detail below. LNP A comprises Compound 1 as the sialic acid lipid (1 mole ratio%), Compound I-18 as the ionizable amino lipid (47 mole ratio%), PL-02 as the PEG-lipid (2 mole ratio%), DSPC as the phospholipid (11 mole ratio%), and cholesterol as the structural lipid (39 mole ratio%). LNP B comprises Compound 1 as the sialic acid lipid (0.5 mole ratio%), Compound I-18 as the ionizable amino lipid (47 mole ratio%), PL-02 as the PEG-lipid (2.5 mole ratio%), DSPC as the phospholipid (11 mole ratio%), and cholesterol as the structural lipid (39 mole ratio%). LNP C comprises Compound 9 as the sialic acid lipid (1 mole ratio%), Compound I-18 as the ionizable amino lipid (47 mole ratio%), PL-02 as the PEG-lipid (2 mole ratio%), DSPC as the phospholipid (11 mole ratio%), and cholesterol as the structural lipid (39 mole ratio%). Attorney Docket No.: 45817-0174WO1 LNP D comprises PEG-DSG as an alternative to the sialic acid lipid (1 mole ratio%), Compound I-18 as the ionizable amino lipid (47 mole ratio%), PL-02 as the PEG-lipid (2 mole ratio%), DSPC as the phospholipid (11 mole ratio%), and cholesterol as the structural lipid (39 mole ratio%). LNP E comprises Compound 1 as the sialic acid lipid (1 mole ratio%), Compound I-18 as the ionizable amino lipid (47 mole ratio%), PL-02 as the PEG-lipid (2 mole ratio%), DSPC as the phospholipid (11 mole ratio%), and cholesterol as the structural lipid (39 mole ratio%). Note that LNP E is made by a different process than LNP A. Specifically the point of addition of sialic acid in LNP A is PI while for LNP E it is the core (see Example 12). In a particular aspect, the disclosure provides a delivery vehicle (e.g., a nanoparticle such as a LNP), wherein the delivery vehicle is formulated with a polynucleotide comprising a messenger RNA (mRNA) comprising: (i) a 5′ UTR (e.g., SEQ ID NO: 15); (ii) an open reading frame (ORF) comprising a nucleic acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO: 165; (iii) a stop codon (assuming a stop codon is not present at the N-terminus of the 3’UTR); and (iv) a 3′ UTR (e.g., SEQ ID NO: 167). In some instances, the mRNA comprises a 5’-terminal cap such as m7G-ppp-Gm. In certain instances, the mRNA comprises a poly A region of about 100 nucleotides in length. In some cases, the mRNA comprises a 5’-terminal cap such as m7G-ppp-Gm and a poly A region of about 100 nucleotides in length. In one instance, the delivery vehicle is a LNP. In a particular case, the LNP is LNP1. In another case, the LNP is any one of LNP A, B, C, D, or E. In one aspect, the disclosure provides a pharmaceutical composition comprising a lipid nanoparticle, wherein the LNP comprises a polynucleotide comprising a messenger RNA. The mRNA comprises: (i) a 5′ UTR consisting of the sequence of SEQ ID NO:15; (ii) an open reading frame (ORF) comprising a nucleotide sequence that encodes an amino acid sequence that is 100% identical to any one of the sequences of SEQ ID Attorney Docket No.: 45817-0174WO1 NO: 177 or 166; (iii) a stop codon if not present in (ii) or at the N-terminus of 3’-UTR; and (iv) a 3′ UTR consisting of the sequence of SEQ ID NO:167. In some instances, of the uracils of the mRNA are N1-methylpseudouracils.. In some cases, the lipid nanoparticle comprises Compound I-18 at 47 mole ratio %, PL-02 at 3 mole ratio %, DSPC at 11 mole ratio %, and cholesterol at 39 mole ratio %. In certain cases, the mRNA comprises a 5’-terminal cap such as m7G-ppp-Gm and a poly A region of about 100 nucleotides in length. In some cases, the mRNA may also encode a Treg epitope. In some cases, the pharmaceutical composition comprises a lipid nanoparticle comprising a first polynucleotide comprising an mRNA encoding a fusion polypeptide described herein and a second polynucleotide comprising a second mRNA encoding an immunomodulator described herein (e.g., an IL2 mutein, an inhibitor of mTOR (e.g., MORG1, PRAS40, DEPTOR), an activator of TGFβ (e.g., ITB6, ITB8), an NFĸB inhibitor, or a PI3K / AKT inhibitor). In another aspect, the disclosure features a pharmaceutical composition comprising a lipid nanoparticle and a means for inducing tolerance to a PBC-associated antigen (e.g., one or more of PDC-E2, E3P, BCOADC-E2, and OGDC-E2). In some cases, the LNP is any one of LNP1, LNP A, LNP B, LNP C, LNP D, or LNP E. In some cases, the means for inducing tolerance to a PBC-associated antigen is a modified mRNA such as the sequence set forth in SEQ ID NO:165. The means for inducing tolerance to a PBC-associated antigen is formulated with the LNP. In yet another aspect, the disclosure features a pharmaceutical composition comprising a means for delivering a polynucleotide to a human subject and a means for inducing tolerance to a PBC-associated antigen (e.g., one or more of PDC-E2, E3P, BCOADC-E2, and OGDC-E2). In some cases, the means for inducing tolerance to a PBC-associated antigen is a modified mRNA such as the sequence set forth in SEQ ID NO:165. The means for inducing tolerance to a PBC-associated antigen is formulated with the LNP. In another aspect, the disclosure features a pharmaceutical composition comprising a lipid nanoparticle, a means for inducing tolerance to a PBC-associated Attorney Docket No.: 45817-0174WO1 antigen (e.g., one or more of PDC-E2, E3P, BCOADC-E2, and OGDC-E2), and a means for inducing suppressive antigen-specific Tregs when the route of administration is intradermal, subcutaneous, or intramuscular. In some cases, the LNP is any one of LNP1, LNP A, LNP B, LNP C, LNP D, or LNP E. In some cases, the means for inducing tolerance to a PBC-associated antigen is a modified mRNA such as the sequence set forth in SEQ ID NO:165. In certain cases, the means for inducing suppressive antigen-specific Tregs when the route of administration is intradermal, subcutaneous, or intramuscular is an mRNA encoding an immunomodulator described herein. The means for inducing tolerance to a PBC-associated antigen and the means for inducing suppressive antigen- specific Tregs when the route of administration is intradermal, subcutaneous, or intramuscular is co-formulated with the LNP. In another aspect, the disclosure relates to a method of promoting tolerance to an antigen in a subject (e.g., human), the method comprising administering to the subject an effective amount of a fusion polypeptide described herein, a polynucleotide described herein, an mRNA or mRNAs described herein, a combination described herein, a pharmaceutical composition described herein, or a lipid nanoparticle described herein. In some cases, the administration is performed intravenously, subcutaneously, intramuscularly, intradermally, via inhalation, or via ingestion. In certain cases, the antigen is an autoantigen, a foreign antigen, an allergen, a protein therapeutic, or a protein that the host immune system considers foreign during therapeutic replacement or transplantation. In one case the antigen is any one or more of human PDC-E2, human E3BP, human OGDC-E2, or human BCOADC-E2 and the fusion polypeptide comprises an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO:166. In one case the antigen is any one or more of human PDC-E2, human E3BP, human OGDC-E2, or human BCOADC-E2 and the mRNA comprises a nucleotide sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ Attorney Docket No.: 45817-0174WO1 ID NO:165. In another case the antigen is any one or more of human PDC-E2, human E3BP, human OGDC-E2, or human BCOADC-E2 and the mRNA encodes a fusion polypeptide comprising an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of any one of SEQ ID NO:169, 177, or 166. In some cases, the method also involves administration of an mRNA that encodes an immunomodulator described herein (e.g., an IL2 mutein, an inhibitor of mTOR (e.g., MORG1, PRAS40, DEPTOR), an activator of TGFβ (e.g., ITB6, ITB8), an NFĸB inhibitor, or a PI3K / AKT inhibitor). In some cases, the mRNA or mRNAs is / are formulated in an LNP such as LNP1. In some case administration is by IV bolus. The IV bolus can be by rapid 10 minute infusion. In another case, the disclosure features a method of promoting tolerance to an autoantigen or autoantigens associated with primary biliary cholangitis (PBC) in a human subject in need thereof. In some cases, the autoantigen or autoantigens associated with PBC is one or more of: human PDC-E2, human E3BP, human OGDC-E2, or human BCOADC-E2. The method comprises administering to the human subject an effective amount of a delivery vehicle or composition comprising a polynucleotide comprising an mRNA encoding a sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence set forth in any one of SEQ ID NO: 169, 177, or 166; or an mRNA that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO: 165. In some cases, administration is by IV bolus. In certain cases, administration is by IV bolus rapid 10 minute infusion. In another aspect, the disclosure relates to a method of promoting tolerance to an antigen in a subject (e.g., human), the method comprising administering to the subject an effective amount of a therapeutic composition comprising a lipid nanoparticle of this disclosure comprising an mRNA or mRNAs described herein. In certain instances, the lipid nanoparticle comprises an ionizable amino lipid, a structural lipid, a phospholipid, Attorney Docket No.: 45817-0174WO1 and a polyethylene glycol (PEG)-modified lipid. In some cases, the LNP is one of LNP1 or LNP2. In some instances, the lipid nanoparticle comprises a sialic acid lipid, an ionizable amino lipid, a structural lipid, a phospholipid, and a polyethylene glycol (PEG)- modified lipid. In some cases, the LNP is one of LNP A, LNP B, LNP C, LNP D, or LNP E. In some cases, the administration is performed intravenously, subcutaneously, intramuscularly, intradermally, via inhalation, or via ingestion. In certain cases, the antigen is an autoantigen, a foreign antigen, an allergen, a protein therapeutic, or a protein that the host immune system considers foreign during therapeutic replacement or transplantation. In some cases, the mRNA comprises a nucleotide sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO:165. In some cases, the mRNA encodes a fusion polypeptide comprising an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of any one of SEQ ID NO:169, 177, or 166. In some cases, the method also involves administration of an mRNA that encodes an immunomodulator described herein (e.g., an IL2 mutein, an inhibitor of mTOR (e.g., MORG1, PRAS40, DEPTOR), an activator of TGFβ (e.g., ITB6, ITB8), an NFĸB inhibitor, or a PI3K / AKT inhibitor). In certain cases, the mRNA is formulated in an LNP such as LNP1.In some case administration is by IV bolus. The IV bolus can be by rapid 10 minute infusion. In another aspect, the disclosure features a method for peripheral induction of Tregs, a method for suppression of effector T cell activation to drive anergy / non- responsiveness or deletion, or a method for enhancing Treg suppressive functionality when the route of administration is intradermal, subcutaneous, or intramuscular. The method comprises administering a therapeutic amount of the fusion polypeptide and the immunomodulator. In some cases, the method comprises administering a therapeutic amount of an mRNA or mRNAs encoding the fusion polypeptide and the immunomodulator. In certain cases, the mRNAs encoding the fusion polypeptide and the Attorney Docket No.: 45817-0174WO1 immunomodulator are coformulated in a single LNP. In other cases, the fusion polypeptide and the immunomodulator are formulated in separate LNPs. In certain cases, the LNP is one of LNP1, LNP A, LNP B, LNP C, LNP D, or LNP E. In certain cases, the immunomodulator is encoded by an mRNA that encodes an amino acid sequence that comprises a sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to a sequence set forth in any one of SEQ ID NOs.: 156, 158, 160, 162, 164, 182, or 185. In other cases, the immunomodulator is encoded by an mRNA that comprises a nucleotide sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to a sequence set forth in any one of SEQ ID NOs.: 157, 159, 161, 163, 181, or 184. In certain cases, all the uracils of the mRNA or mRNAs are N1-methylpseudouracil. In some cases, an effective amount is 0.001 mg / kg, 0.002 mg / kg, 0.003 mg / kg, 0.004 mg / kg, 0.005 mg / kg, 0.006 mg / kg, 0.007 mg / kg, 0.008 mg / kg, 0.009 mg / kg, 0.010 mg / kg, 0.020 mg / kg, 0.030 mg / kg, 0.040 mg / kg, 0.050 mg / kg, 0.060 mg / kg, 0.070 mg / kg, 0.080 mg / kg, 0.090 mg.kg, 0.1 mg / kg, 0.15 mg / kg, 0.2 mg / k, or 0.3 mg / kg. In some cases, an effective amount is between 0.001 mg / kg and 0.050 mg / kg. In some cases, an effective amount is between 0.005 mg / kg and 0.010 mg / kg. In some cases, an effective amount is between 0.005 mg / kg and 0.1 mg / kg. In certain cases, an effective amount is about 0.001 mg / kg. In other cases, an effective amount is about 0.01 mg / kg. In some cases, an effective amount is 10 µg / kg or about 10 µg / kg. The dose to be administered is chosen based on (1) immune response outcome depending on "antigenicity" of the antigen for tolerization, (2) mRNA length / moles of mRNA dosed and (3) if multiplexing (i.e., providing multiple mRNAs) - total dose vs. dose of each antigen. In another aspect, the disclosure provides a method of treating Myelin oligodendrocyte glycoprotein antibody disease (MOGAD) in a human subject in need thereof. The method comprises administering to the human subject an effective amount of Attorney Docket No.: 45817-0174WO1 a MOG fusion polypeptide described herein, a MOG fusion polypeptide encoding polynucleotide described herein, a MOG fusion polypeptide encoding mRNA described herein, a combination of a MOG fusion polypeptide encoding polynucleotide (e.g., mRNA) and an mRNA encoding an IL2 mutein or a Treg epitope, or a mTOR inhibitor (e.g., MORG1, PRAS40, DEPTOR), a pharmaceutical composition described herein, or a lipid nanoparticle described herein. In another aspect, the disclosure provides a method of treating celiac disease in a human subject in need thereof. The method comprises administering to the human subject an effective amount of a gliadin or transglutaminase fusion polypeptide described herein, a gliadin or transglutaminase fusion polypeptide encoding polynucleotide described herein, a gliadin or transglutaminase fusion polypeptide encoding mRNA described herein, a combination of a gliadin or transglutaminase fusion polypeptide encoding polynucleotide (e.g., mRNA) and an mRNA encoding an IL2 mutein or a Treg epitope, or a mTOR inhibitor (e.g., MORG1, PRAS40, DEPTOR), a pharmaceutical composition described herein, or a lipid nanoparticle described herein. In another aspect, the disclosure provides a method of treating primary biliary cholangitis in a human subject in need thereof. The method comprises administering to the human subject an effective amount of a fusion polypeptide of a T cell epitope(s) of an antigen(s) known to be associated with the disease (e.g., one or more of human PDC-E2, human E3P, human BCOADC-E2, and / or human OGDC-E2), a polynucleotide encoding such a fusion polypeptide, a mRNA encoding such a fusion polypeptide, a combination of a polynucleotide or mRNA encoding such a fusion polypeptide and an mRNA encoding an immunomodulator such as an IL2 mutein, an mTOR inhibitor (e.g., MORG1, PRAS40, DEPTOR), a TGFβ activator (e.g., ITB6, ITB8), or another immunomodulator described herein, a pharmaceutical composition described herein, or a lipid nanoparticle described herein. In one aspect, the disclosure provides a method of treating primary biliary cholangitis in a human subject in need thereof. In one case, the method comprises administering to the human subject an effective amount of a polynucleotide comprising Attorney Docket No.: 45817-0174WO1 an mRNA comprising a nucleotide sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO:165. In another case, the method comprises administering to the human subject an effective amount of a polynucleotide comprising an mRNA encoding an amino acid sequence that is at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of any one of SEQ ID NOs: 177 or 166. In some cases, the mRNA comprises a 5’-UTR (e.g., SEQ ID NO:15) and a 3’-UTR (e.g., SEQ ID NO:167). In some cases, the mRNA comprises a 5’terminal cap (e.g., m7G-ppp-Gm) and a poly A region (e.g., a poly A of about 100 nt). In some instances, the method also involves administering a polynucleotide comprising a second mRNA encoding an immunomodulator described herein such as an IL2 mutein (SEQ ID NO: 156 or 158), an mTOR inhibitor (e.g., MORG1, PRAS40, DEPTOR) (SEQ ID NO: 160, 162, 164), a TGFβ activator (e.g., ITB6, ITB8), or any other immunomodulator. In certain cases, the mRNA or mRNAs is / are formulated in an LNP such as LNP1. In some cases, the effective amount is between about 0.005 mg / kg and about 0.1 mg / kg. In some case administration is by IV bolus (e.g., rapid infusion in about 10 minutes). In another aspect, the disclosure provides a method of treating myasthenia gravis in a human subject in need thereof. The method comprises administering to the human subject an effective amount of a fusion polypeptide of the antigen known to be associated with the disease described herein (e.g., nAChR, MuSK, Lrp4, Agrin), a polynucleotide encoding such a fusion polypeptide, a mRNA encoding such a fusion polypeptide, a combination of a polynucleotide or mRNA encoding such a fusion polypeptide and an mRNA encoding an IL2 mutein or a Treg epitope, a pharmaceutical composition described herein, or a lipid nanoparticle described herein. In another aspect, the disclosure provides a method of treating Grave’s disease in a human subject in need thereof. The method comprises administering to the human subject an effective amount of a fusion polypeptide of the antigen known to be associated Attorney Docket No.: 45817-0174WO1 with the disease described herein (e.g., Thyroid stimulating hormone receptor), a polynucleotide encoding such a fusion polypeptide, a mRNA encoding such a fusion polypeptide, a combination of a polynucleotide or mRNA encoding such a fusion polypeptide and an mRNA encoding an IL2 mutein or a Treg epitope, a pharmaceutical composition described herein, or a lipid nanoparticle described herein. In yet another aspect, the disclosure provides a method of treating NMOSD in a human subject in need thereof. The method comprises administering to the human subject an effective amount of a fusion polypeptide of the antigen known to be associated with the disease described herein (e.g., AQP-4), a polynucleotide encoding such a fusion polypeptide, a mRNA encoding such a fusion polypeptide, a combination of a polynucleotide or mRNA encoding such a fusion polypeptide and an mRNA encoding an IL2 mutein or a Treg epitope, a pharmaceutical composition described herein, or a lipid nanoparticle described herein. In a further aspect, the disclosure provides a method of treating Pemphigus in a human subject in need thereof. The method comprises administering to the human subject an effective amount of a fusion polypeptide of the antigen known to be associated with the disease described herein (e.g., Dsg1, Dsg3), a polynucleotide encoding such a fusion polypeptide, a mRNA encoding such a fusion polypeptide, a combination of a polynucleotide or mRNA encoding such a fusion polypeptide and an mRNA encoding an IL2 mutein or a Treg epitope, a pharmaceutical composition described herein, or a lipid nanoparticle described herein. In another aspect, the disclosure provides a method of treating ankylosing spondylitis in a human subject in need thereof. The method comprises administering to the human subject an effective amount of a fusion polypeptide of the antigen known to be associated with the disease described herein (e.g., HLA-B27 antigen), a polynucleotide encoding such a fusion polypeptide, a mRNA encoding such a fusion polypeptide, a combination of a polynucleotide or mRNA encoding such a fusion polypeptide and an mRNA encoding an IL2 mutein or a Treg epitope, a pharmaceutical composition described herein, or a lipid nanoparticle described herein. Attorney Docket No.: 45817-0174WO1 In yet another aspect, the disclosure provides a method of treating Type 1 diabetes in a human subject in need thereof. The method comprises administering to the human subject an effective amount of a fusion polypeptide of the antigen known to be associated with the disease described herein (e.g., insulin, glutamic acid decarboxylase, islet antigen-2, zinc transporter 8), a polynucleotide encoding such a fusion polypeptide, a mRNA encoding such a fusion polypeptide, a combination of a polynucleotide or mRNA encoding such a fusion polypeptide and an mRNA encoding an IL2 mutein or a Treg epitope, a pharmaceutical composition described herein, or a lipid nanoparticle described herein. In certain cases, the above methods employ as a delivery vehicle one of LNP1, LNP2, LNP A, LNP B, LNP C, LNP D, or LNP E; optionally one of LNP A, LNP B, LNPC, or LNP E. In one particular case, the delivery vehicle is LNP1. In some cases, administration is performed intravenously, subcutaneously, or intramuscularly. In one case, administration is by IV bolus (e.g., rapid infusion in about 10 minutes). In some cases, an effective amount is 0.001 mg / kg, 0.002 mg / kg, 0.003 mg / kg, 0.004 mg / kg, 0.005 mg / kg, 0.006 mg / kg, 0.007 mg / kg, 0.008 mg / kg, 0.009 mg / kg, 0.010 mg / kg, 0.020 mg / kg, 0.030 mg / kg, 0.040 mg / kg, 0.050 mg / kg, 0.060 mg / kg, 0.070 mg / kg, 0.080 mg / kg, 0.090 mg / kg, 0.1 mg / kg, 0.15 mg / kg, 0.2 mg / kg, or 0.3 mg / kg. In some cases, an effective amount is between 0.001 mg / kg and 0.050 mg / kg. In certain cases, an effective amount is between about 0.005 mg / kg and about 0.010 mg / kg. In some cases, an effective amount is between 0.005 mg / kg and 0.010 mg / kg. In certain cases, an effective amount is about 0.001 mg / kg. In other cases, an effective amount is about 0.01 mg / kg. BRIEF DESCRIPTION OF THE DRAWINGS FIG.1A is a graph showing the frequency of antigen-specific CD4 T cells after naïve C57BL / 6 mice were administered with a dose titration of mRNA encoding MOG27-63 antigen formulated with either LNP1(circle) or LNP2 (triangle) . Three days after the final boost spleens were processed to single cell suspensions and antigen- Attorney Docket No.: 45817-0174WO1 specific T cells assessed by MOG35-55T cell tetramer staining and high dimensional immunophenotyping. Significance evaluated with one-way ANOVA. FIG.1B is a graph showing the percentage of antigen-specific T cells that were FOXP3+ (Treg) after naïve C57BL / 6 mice were administered with a dose titration of mRNA encoding MOG27-63 antigen formulated with either LNP1 (circle) or LNP2 (triangle) . Three days after the final boost spleens were processed to single cell suspensions and antigen-specific T cells assessed by MOG35-55 T cell tetramer staining and high dimensional immunophenotyping. FIG.2 are a set of graphs showing the antigen-specific T cells in the spleen and peripheral blood after intravenous, subcutaneous, or intramuscular dosing. Naïve C57BL / 6 mice were immunized intravenously (IV), subcutaneously (SQ) or intramuscularly (IM) with LNP2 MOG27-63 or an irrelevant mRNA following the standard ASIT dosing regimen. Three days after the final boost spleen and blood was collected and processed to single-cell suspensions and antigen-specific T cells assessed by MOG35-55T cell tetramer staining and high dimensional immunophenotyping. Significantly more antigen-specific Tregs were found in the spleen and blood with IM dosing compared to IV and SQ dosing. Statistical analysis was assessed with a one-way ANOVA Tukey’s multi-comparison post-test. Significance is noted. N.S. = not significant. FIG.3 are a set of graphs showing that professional antigen-presenting cells are more important than hepatocytes for inducing antigen-specific Tregs. MOG27-63 mRNA with either no microRNA (miR), miR142 which reduces translation in myeloid cells, or miR122 which reduces translation in hepatocytes formulated in LNP2. C57BL / 6 mice were dosed following the standard ASIT dosing regimen. Three days after the final boost spleen and blood was collected and processed to single-cell suspensions and antigen- specific T cells assessed by MOG35-55 T cell tetramer staining and high dimensional immunophenotyping. Antigen-specific T cell responses were significantly lower in the group that received MOG27-63 miR142, indicating the importance of myeloid cells in Attorney Docket No.: 45817-0174WO1 inducing antigen-specific T cells responses. Statistical analysis assessed with a one-way ANOVA Tukey’s multi-comparison post-test. FIG.4 is a graph showing that antigen-specific Tregs are readily expanded with a single boost (LNP2). C57BL / 6 mice were immunized following our standard naïve mouse dosing regimen and then rested for increasing amounts of time and either boosted or given an irrelevant mRNA. Three days after the final boost spleen and blood was collected and processed to single-cell suspensions and antigen-specific T cells assessed by MOG35-55T cell tetramer staining and high dimensional immunophenotyping. Antigen-specific Treg responses contracted to baseline within 10 days but were readily re-expanded with a single boost. FIG.5 depicts a series of graphs that show that antigen specific immunotherapy (LNP2) induced durable protection in the EAE animal model. C57BL / 6 mice were either immunized on day 6 and 9 following EAE induction or were administered antigen specific immunotherapy on day 1 and 4 and EAE induced on either day 21 or day 35. Statistically significant protection was noted in all groups. Statistical analysis was assessed with a one-way ANOVA with a Tukey’s multiple comparison post-test. FIG.6 is a graph that shows that antigen specific immunotherapy can treat pre- established EAE symptoms. EAE was induced and symptoms monitored. When animals reached an EAE score = 1 they were administered with LNP2 MOG27-63 and boosted three days later. Antigen specific immunotherapy halted disease progression for the duration of the experiment. FIG.7A is a graph showing that the antigen source impacts T cell fate outcome. Naïve C57BL / 6 mice were immunized with our standard ASIT dosing regimen using mRNA encoding either MOG27-63, I-Eα52-68, OVA320-344 or LCMV61-80 formulated with LNP2. Three days after the final boost collected spleens were processed to single-cell suspensions and antigen-specific T cells assessed by T cell tetramer staining and high dimensional immunophenotyping. Tetramer positive CD4 T cells plotted by FOXP3+ versus FOXP3- demonstrated that while MOG-specific and I-Eα-specific T Attorney Docket No.: 45817-0174WO1 cells skew toward FOXP3+ Tregs the foreign antigens OVA and LCMV skew toward FOXP3- T cells. FIG.7B are graphs that show that either co-delivering a Treg-inducing antigen like MOG or in an antigen independent manner with IL-2 mutein can skew T cell responses to OVA toward a Treg. FIG.8A is a graph showing the effect of using a LAMP1 C-terminal sequence as the endosomal targeting antigen. OVA320-344 with either MITD, mouse invariant chain 1-80 (mLi) or mouse LAMP1344-382was used in our standard ASIT dosing regimen (LNP2). LAMP1344-382 did not activate CD8 T cells as much as MITD while inducing similar levels of antigen-specific CD4 T cells. FIG.8B is a graph showing that MITD and LAMP1344-382induced similar levels of antigen-specific CD4 T cells. FIG.9 is a graph depicting antigen-specific T cell responses after administering the ectodomain of human or mouse MOG (LNP2). FIG.10A shows serum cytokines evaluated by Luminex using a blood draw 3 hours post intravenous dosing of LNPs at 1 mg / kg. C57BL / 6 mice were immunized with our standard ASIT dosing regimen using LNP1 and LNPs A, B, C, and D. LNPs that contained either alpha2-6 linked sialyllactose (Compound 1 of Table SA-1) or alpha2-3 linked sialyllactose (Compound 9 of Table SA-1) serve as PEG replacements. Sialic acid eliminated mRNA LNP reactogenicity. FIG.10B depicts a series of graphs showing that LNPs with sialic acid (LNPs A, B, C, D) increased total antigen-specific T cells response which coincided with an increase in antigen-specific Tregs and T follicular regulatory cells relative to LNP1. FIG.11A is a depiction of the analysis of blood collected three hours after dosing with LNP1, LNPA, or sialic acid in solution (0.38 mg / kg). Compound 1 was used as a PEG replacement or the corresponding α2-6 sialyllactose was co-delivered in the LNP solution. C57BL / 6 mice were dosed with LNP at 2 mg / kg. Sialic acid both in solution and directly attached to the LNP as a PEG replacement reduced mRNA LNP reactogenicity but was more efficient when attached to the LNP. Attorney Docket No.: 45817-0174WO1 FIG.11B shows that Compound 1 as a PEG replacement changes distribution with reduced transfection of all cell types in the spleen except for marginal zone macrophage and possibly dendritic cells. FIG.12 is an example of a flow-chart of Post insertion, post addition (PIPA) process where sialic acid lipids were incorporated in the lipid stock solution. In this process sialic acid lipid (Compound 1 and Compound 9 of Table SA-1) was incorporated in the nanoprecipitation stage. FIG.13 is an example of a flow-chart of PIPA process where sialic acid lipids were added in the post insertion (PI) stage. FIG.14 are graphs showing total Treg expansion using FOXP3 expression and antigen-specific Treg expansion using the activation induced marker assay in non-human primates following intravenous immunization with MOG 1-125 with our without IL-2 mutein. FIG.15 are graphs showing antigen-specific T cell activation of FOXP3+ and FOXP3- T cells following ex vivo restimulation with overlapping MOG peptides using PBMCs from immunization of non-human primates. After 10 hours of stimulation PBMCs were stained with an antibody panel and upregulation of CD69 and OX40 evaluated by flow cytometry. The data show that the majority of MOG antigen-specific T cells were FOXP3+. FIG.16 is a graph showing the anti-MOG IgG1 serum concentrations and MOG- specific Tregs following intravenous dosing of non-human primates. As antigen-specific Tregs were induced and expanded the MOG antibody titers were suppressed. FIG.17 provides data of C57BL / 6 mice that were immunized with different primary biliary cholangitis antigen designs. Splenocytes were used for an ex vivo activation induced marker assay looking for CD25+ ICOS+ (Treg biased) or CD69+ CD40L+ (effector T cell bias) T cells. Only CD25+ ICOS+ T cells were identified, indicating vaccination with these antigens primarily induced antigen-specific Tregs. FIG.18 are graphs of examples of human DRB4*01:01 PBMCs used in an antigen-specific T cell expansion experiment. Either PDC-E2163-176 peptide or a pool of 5 Attorney Docket No.: 45817-0174WO1 other peptides were used. Simultaneously monocyte derived dendritic cells (moDCs) were generated. The moDCs were either transfected with the PBC mRNA LNP or peptide pulsed and the magnitude of T cell activation was assessed. For both the PDC-E2163-176 peptide or a pool of 5 other peptides there was a strong correlation between the mRNA transfected moDCs and the peptide pulsed moDCs indicating proper mRNA antigen processing and presentation. FIG.19 are graphs illustrating the use of an mRNA-encoded mTOR inhibitor. The mTOR inhibitor PRAS40 was encoded as mRNA and transfected into mouse bone marrow derived dendritic cells (BMDCs). Torin-1 is a well-known small molecule mTOR inhibitor. PRAS40 suppressed phosphorylation of 4EBP and S6K following TNFα stimulation indicating that it was functioning as a mTOR1 inhibitor similar to Torin-1. FIG.20 are graphs showing antigen-specific Treg induction to a foreign antigen by using integrin beta 6 to activate TGFβ. The top graph shows the percent of proliferating cells in the OTII (CD45.2+) population on D5 in the spleen. Proliferation is measured as CFSElocells. The bottom graph shows the frequency of regulatory T cells (Tregs, Foxp3+) in the OTII (CD45.2+) population on Day 5 in the spleen. Statistics defined as P<0.05 using One-way ANOVA versus irrelevant mRNA 1 mg / kg treatment group. Statistical analysis performed with GraphPad. DETAILED DESCRIPTION Provided herein are antigen specific immunotherapies for use in antigen-specific or tissue-specific tolerization, which is a strategy that selectively targets autoreactive lymphocytes while leaving the immune system intact and functional, to enable disease control without compromising immunity. These antigen-specific tolerization immunotherapies can be used for treating or preventing diseases or disorders (e.g., autoimmune diseases, allergies, inflammatory diseases), in reducing the generation of anti-drug antibodies (ADA) when administering therapeutics either pre-treatment or post- Attorney Docket No.: 45817-0174WO1 immune response, as well as in transplant settings (e.g., pre-transplant). Importantly, these antigen-specific tolerization immunotherapies can be used at low doses – i.e., they can be dosed up to 100-fold lower than with previous antigen specific immunotherapies. These tolerization immunotherapies when administered as an LNP comprising an mRNA(s) encoding an antigen for tolerization demonstrate antigen-specific Treg induction when dosed subcutaneously and intramuscularly. In addition, the disclosure shows that in some cases, in addition to dosing antigen alone (as done here with MOG), the inclusion of an immunomodulator (e.g., an IL-2 mutein, a Treg epitope, a mTOR1 inhibitor) may be needed for certain antigenic sequences used for tolerization, particularly alloantigens or foreign antigens that have not gone through central tolerance and do not have a pre-existing pool of Tregs or when there is a pre-existing inflammatory state in disease which may impact tolerogenic antigen presentation. Also provided are LNPs with reduced reactogenicity to improve tolerability and reduce risk of inducing inflammation while delivering an autoantigen that could exacerbate disease in humans who are much more sensitive to mRNA LNP dosing relative to rodents. Antigens Used for Inducing Tolerance The antigen specific immunotherapy (ASIT) of this disclosure is directed at inducing or restoring an immunological state of unresponsiveness towards a particular antigen. Such immunotherapies dampen the adverse response of T cells through deletion, inhibition, or deviation of antigen-specific effector T cells (Teffs) and promote the induction and / or expansion of antigen-specific T regulatory cells (Tregs). T regs are a cell population responsible for maintaining immune tolerance. In addition to controlling disease causing effector T cells, Tregs can also prevent anti-drug antibodies (ADAs), transplant rejection, B cell driven autoimmunity, or IgE-mediated allergy by inhibiting antibody class switching and B cell proliferation. The disclosure provides a fusion polypeptide which induces tolerance in a human subject to a selected protein or proteins. The fusion polypeptide comprises a first amino Attorney Docket No.: 45817-0174WO1 acid sequence which comprises at least one T cell epitope derived from the selected protein or proteins fused directly or via a linker to an endolysosomal targeting sequence. In some instances, the selected protein or proteins is a self-antigen or autoantigen. In other instances, the selected protein or proteins is a foreign antigen. In certain cases, the selected protein or proteins is an allergen. In other cases, the selected protein or proteins is a protein therapeutic (e.g., recombinant protein as replacement therapy or an antibody or antigen-binding fragment thereof). In yet other cases, the selected protein or proteins is a protein that the host immune system considers foreign during therapeutic replacement or transplantation. In certain instances, the first amino acid sequence comprises or consists of a single T cell epitope of the antigen. In other instances, the first amino acid sequence comprises or consists of a string of T cell epitopes of the antigen. In yet other instances, the first amino acid sequence comprises or consists of a shuffled T cell epitope(s) of the antigen. In some cases, the first amino acid sequence is a subunit of a protein. In other cases, the first amino acid sequence is a partial sequence of the protein against which tolerance is sought. In yet other cases, the first amino acid sequence is the full amino acid sequence of the protein against which tolerance is sought. In some instances, the first amino acid sequence can be any antigen, subunit of an antigen, a T cell epitope(s) of antigen where the antigen is known to be involved in a disease of interest (e.g., autoimmune disease, allergy, inflammatory disease). See, e.g., Kenison, J.E., Stevens, N.A. & Quintana, F.J. Therapeutic induction of antigen-specific immune tolerance. Nat Rev Immunol (2023). doi.org / 10.1038 / s41577-023-00970-x; Schurgers et al., Front. Immunol., 09 September 2021, Sec. Immunological Tolerance and Regulation, Volume 12 - 2021 | doi.org / 10.3389 / fimmu.2021.742695; Steinman et al., Current Opinion in Immunology, Volume 61, December 2019, Pages 46-53; incorporated by reference herein. In other instances, the first amino acid sequence can be any antigen used as a therapeutic agent or for pre-treatment in a transplantation setting. In certain instances, the first amino acid sequence comprises a T cell epitope (e.g., an immunodominant epitope) of a self-antigen. In some cases, the first amino acid Attorney Docket No.: 45817-0174WO1 sequence is myelin oligodendrocyte protein (MOG). In certain cases, the first amino acid sequence comprises the extracellular domain of MOG. In some cases, the first amino acid sequence comprises the transmembrane domain of MOG. In other cases, the first amino acid sequence comprises the cytoplasmic domain of MOG. In some cases, the first amino acid sequence comprises amino acids 35 to 55 of human MOG with 0, 1, 2, 3, 4, 5, 6, 7, or 8 substitutions. These substitutions still permit MHC binding and / or T cell proliferative response. The human MOG35-55 amino acid sequence is MEVGWYRPPFSRVVHLYRNGK (SEQ ID NO: 35). One exemplary variant of human MOG35-55 amino acid sequence is MEVGWYRSPFSRVVHLYRNGK (SEQ ID NO:36). In some cases, the first amino acid sequence comprises or consists of an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to SEQ ID NO:35. In certain cases, the first amino acid sequence comprises amino acids 27 to 63 of human MOG with 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 substitutions. In some instances, the substitutions can be made to replace a human MOG amino acid(s) with a corresponding amino acid(s) in the murine MOG sequence. These substitutions still permit MHC binding and / or T cell proliferative response. The human MOG27-63amino acid sequence is: SPGKNATGMEVGWYRPPFSRVVHLYRNGKDQDGDQAP (SEQ ID NO:34). In some instances, one or more (1, 2, 3, 4, 5) of the amino acids shown in bold can be substituted with the counterpart amino acid from murine MOG. Exemplary variants of the human MOG27-63 amino acid sequence are: SPGKNATGMEVGWYRSPFSRVVHLYRNGKDQDGDQAP (SEQ ID NO:37) SPGKNATGMEVGWYRPPFSRVVHLYRNGKDQDADQAP (SEQ ID NO:38) SPGKNATGMEVGWYRPPFSRVVHLYRNGKDQDGEQAP (SEQ ID NO:39) SPGKNATGMEVGWYRPPFSRVVHLYRNGKDQDGDAAP (SEQ ID NO:40) SPGKNATGMEVGWYRPPFSRVVHLYRNGKDQDGDQQP (SEQ ID NO:41) SPGKNATGMEVGWYRSPFSRVVHLYRNGKDQDAEAQP (SEQ ID NO:42) Attorney Docket No.: 45817-0174WO1 In some cases, the first amino acid sequence comprises or consists of an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to SEQ ID NO:34. In certain cases, the first amino acid sequence comprises amino acids 1 to 125 of human MOG with 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 substitutions. In some instances, the substitutions can be made to a corresponding amino acid(s) in the murine MOG sequence. These substitutions still permit MHC binding and / or T cell proliferative response. The human MOG1-125 amino acid sequence is: GQFRVIGPRHPIRALVGDEVELPCRISPGKNATGMEVGWYRPPFSRVVHLYRNG KDQDGDQAPEYRGRTELLKDAIGEGKVTLRIRNVRFSDEGGFTCFFRDHSYQEE AAMELKVEDPFYWVSPG (SEQ ID NO:33) In some cases, the first amino acid sequence comprises or consists of an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to SEQ ID NO:33. In certain instances, the first amino acid sequence comprises the human counterpart sequence corresponding to amino acids 119 to 132 of the transmembrane domain of murine MOG. In certain instances, the antigen comprises the human counterpart sequence corresponding to amino acids 181 to 195 or amino acids 186 to 200 of the cytoplasmic domain of murine MOG. In some instances, the first amino acid sequence is myelin basic protein (MBP). In some cases, the first amino acid sequence is one or more of MBP 30-44, MBP 83-99, MBP 84-102, MBP 131-145, or MBP 140-154. In other cases, the antigen is one or more of MBP 13-32, 83-99, MBP 84-102, MBP 111-129, MBP 143-168, MBP 144-163, MBP 146-170, or MBP 151-170. In some cases, the first amino acid sequence is myelin proteolipid protein PLP or lipophilin (e.g., PLP 139-151, PLP 139-154). In some cases, the antigen is aquaporin (e.g., AQP 463-476). Attorney Docket No.: 45817-0174WO1 In some instances, the first amino acid sequence is proinsulin or glutamic acid carboxylase, or a peptide or T cell epitope(s) thereof. In some instances, the first amino acid sequence is recombinant Factor VIII or a peptide or T cell epitope(s) thereof. In some instances, the first amino acid sequence is gliadin or transglutaminase, or a peptide or T cell epitope(s) thereof. In certain instances, the first amino acid sequence is Sp100 or Nuclear pore glycoprotein 210 (gp210) or T cell epitope(s) thereof. In other instances, the first amino acid sequence is Neuronal nicotinic acetylcholine receptor (nAChR), Muscle-specific Kinase (MuSK), Low-density lipoprotein receptor-related protein 4 (LRP-4), or Agrin, or T cell epitope(s) of any of these. In further instances, the first amino acid sequence is Thyroid stimulating hormone receptor or a T cell epitope(s) thereof. In other instances, the first amino acid sequence is Aquaporin-4 (AQP4) or a T cell epitope(s) thereof. In yet other instances, the first amino acid sequence is noncollagenous-1 (NC1) domain of type IV collagen in the glomerular basement membrane (GBM), or T cell epitope(s) of any of these. In some instances, the first amino acid sequence is Desmosomal adhesion proteins, desmoglein (Dsg)1 or Dsg3 (also known as DG1 and DG3, respectively), or a T cell epitope of any of these. In other instances, the first amino acid sequence is proinsulin, insulin, glutamic acid decarboxylase, islet antigen -2, or Zinc Transporter 8 or T cell epitope(s) of any of these. In some instances, the first amino acid sequence is myosin heavy chain alpha or T cell epitope(s) thereof. In some instances, the first amino acid sequence is an antigen or antigens associated with PBC or T cell epitope(s) thereof. In one instance, the first amino acid Attorney Docket No.: 45817-0174WO1 sequence is a mitochondrial antigen E2 component of the 2-oxo dehydrogenase complexes. In one instance, the antigen for inducing tolerance is the E2 component of mitochondrial pyruvate dehydrogenase complex (PDC-E2) or a T cell epitope thereof. In another instance, the antigen for inducing tolerance is another pyruvate complex protein such as E3 binding protein (E3BP), 2-oxo-glutarate dehydrogenase complex (OGDC-E2), the branched-chain 2-oxoacid dehydrogenase complex (BCOADC-E2), or the E1a component of mitochondrial pyruvate dehydrogenase complex (PDC-E1a), or T cell epitopes of these. Examples of such T cell epitopes are provided below: Antigen Peptide SEQ ID NO: In some cases, the first amino acid sequence comprises each of the sequences set forth in SEQ ID NOs.: 171 through 176. In certain cases, the first amino acid sequence comprises each of the sequences set forth in SEQ ID NOs.: 171 through 176 in order from N- terminus to C-terminus. In some cases, these T cell epitope sequences are linked by a peptide linker such as the one set forth in SEQ ID NO: 168. In other instances, the first amino acid sequence is 21-hydroxylase or T cell epitope(s) thereof. In certain instances, the first amino acid sequence is Thyroglobulin (40 antigenic epitopes), thyroid peroxidase, tyrotropin receptor, or sodium iodide symporter, or T cell epitope(s) thereof of these. Attorney Docket No.: 45817-0174WO1 In other instances, the first amino acid sequence is intrinsic factor (IF) or H+ / K+- ATPase or T cell epitope(s) thereof. In some instances, the first amino acid sequence is a component of the platelet membrane glycoprotein (GP) complex or T cell epitope(s) thereof. In some instances, the first amino acid sequence is GM-CSF or T cell epitope(s) thereof. In certain instances, the first amino acid sequence is HLA B27 associated antigen or T cell epitope(s) thereof. In other instances, the first amino acid sequence is a pancreatic autoantibody or Glycoprotein 2 or T cell epitope(s) thereof. In some instances, the first amino acid sequence is integrin αvβ6 or T cell epitope(s) thereof. In some instances, the first amino acid sequence is Cathelicidin LL-37, melanocytic ADAMTSL5, lipid antigen PLA2G4D, or keratin 17, or T cell epitope(s) thereof. In certain instances, the first amino acid sequence is Melanocyte antigen or T cell epitope(s) thereof. In some instances, the first amino acid sequence is Myelin antigen or T cell epitope(s) thereof. In further instances, the first amino acid sequence is a histone H1, H3, or H4. In certain cases, H1’22-42, H416-39, H471-94, or H382-105or T cell epitope(s) thereof. In other instances, the first amino acid sequence is Rheumatoid Factor that recognize Fc-tail of immunoglobulin (Ig)-Gs, or multiple citrullinated-antigen, or T cell epitope(s) thereof. In yet other instances, the first amino acid sequence is SSA / Ro, SSB / La, ANA, M3R, VIPR, or platelet- selectin, or T cell epitope(s) thereof (see, Tong et al., J Inflamm Res.2017; 10: 97–105.) Attorney Docket No.: 45817-0174WO1 In some instances, the first amino acid sequence is an autoantigen described in WO 2018 / 188730 or WO 2018 / 189193, both of which are incorporated by reference herein in their entirety. In certain cases, the first amino acid sequence comprises or consists of a single T cell epitope of any of the antigens listed above. In other instances, the first amino acid sequence comprises or consists of a string of T cell epitopes of any of the antigens listed above. In yet other instances, the first amino acid sequence comprises or consists of a shuffled T cell epitope(s) of any of the antigens listed above. In some cases, the first amino acid sequence is a subunit of a protein listed above. In other cases, the first amino acid sequence is a partial sequence of a protein listed above. In yet other cases, the first amino acid sequence is the full amino acid sequence of a protein listed above. The first amino acid sequence is linked directly or via a linker (e.g., a peptide linker such as a glycine serine linker or a linker set forth in SEQ ID NO:168) to an endolysosomal targeting sequence. Endolysosomal Targeting Sequence Small peptide sequences are generally involved in ensuring accurate trafficking and distribution of proteins into intracellular compartments. Peptide sequences that are helpful to target a protein to the endosomal and / or lysosomal compartments are used herein. In some instances, the endolysosomal targeting sequence is a sequence of or from a human MHC class I trafficking domain (MITD). In some instances, an amino acid sequence corresponding to the transmembrane and cytoplasmic domain of human MITD is used. In one case, amino acids 308-362 of human MITD with the sequence provided below is employed in the fusion polypeptide: IVGIVAGLAVLAVVVIGAVVAAVMCRRKSSGGKGGSYSQAACSDSAQGSDVSL TA (SEQ ID NO:29). In some cases, the endolysosomal targeting sequence comprises or consists of an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least Attorney Docket No.: 45817-0174WO1 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% identical to the sequence of SEQ ID NO:29. In some instances, the endolysosomal targeting sequence is not a sequence of or from a human MHC class I trafficking domain (MITD). In certain cases, the endolysosomal targeting sequence is not or does not comprise amino acids 308-362 of human MITD. In some instances, the endolysosomal targeting sequence is a sequence of or from a human lysosomal-associated membrane protein (LAMP). In some cases, the endolysosomal targeting sequence is a sequence of or from LAMP1, LAMP2, or dendritic cell (DC)-LAMP. In some cases, the endolysosomal targeting sequence is a sequence of or from a human LAMP comprises a sequence: Y-X-X-Φ, wherein X is any amino acid and Φ is a hydrophobic amino acid. In certain cases, the endolysosomal targeting sequence is a sequence of or from a human LAMP and comprises a sequence: GYQTI (SEQ ID NO:143); YEQF (SEQ ID NO:144); or GYEVM (SEQ ID NO:145). In one case, amino acids 351-389 of human LAMP1 with the sequence provided below is employed in the fusion polypeptide: ENSMLIPIAVGGALAGLVLIVLIAYLVGRKRSHAGYQTI (SEQ ID NO:30). The membrane anchor is shown in bold and the endosomal targeting sequence is underlined. In some cases, the endolysosomal targeting sequence comprises or consists of an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% identical to the sequence of SEQ ID NO:30. In some cases, the endolysosomal targeting sequence comprises or consists of an amino acid sequence of SEQ ID NO:30 with 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 amino acid substitutions. In some cases, the substitutions are conservative. In certain cases, the membrane anchor and / or the endosomal targeting sequence are not substituted. In another case, the endolysosomal targeting sequence is a sequence of or from a human LAMP and comprises a sequence: RKRX1X2X3X4YQTI (SEQ ID NO:31), wherein X1,X2,X3,and X4can be any amino acid. In one instance, X1 =S, X2 = H, X3 =A, and X4 = G. In certain Attorney Docket No.: 45817-0174WO1 instances, the Q and T amino acids towards the C-terminus of SEQ ID NO:31 can be replaced by any amino acid and the I at the very C-terminal can be replaced by any hydrophobic amino acid. In other instances, the endolysosomal targeting sequence is a sequence of or from a human CD74 protein (i.e., the human invariant (Ii) chain. In some instances, the portion of human CD74 that is used includes the cytosolic domain, the transmembrane domain, and the luminal domain. In some cases, the following human Invariant Chain (CD74) (1- 80) sequence is used: MDDQRDLISNNEQLPMLGRRPGAPESKCSRGALYTGFSILVTLLLAGQATTAYFL YQQQGRLDKLTVTSQNLQLENLRMK (SEQ ID NO:32). In some cases, the endolysosomal targeting sequence comprises or consists of an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% identical to the sequence of SEQ ID NO:32. In some cases, the endolysosomal targeting sequence comprises or consists of an amino acid sequence of SEQ ID NO:32 with 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 amino acid substitutions. In some cases, the substitutions are conservative. In some instances, an amino acid(s) in the human sequence can be replaced by an amino acid in the counterpart invariant chain sequence from another species (e.g., mouse). In some cases, the endolysosomal targeting sequence comprises or consists of any amino acid sequence from Table 1. Table 1. Exemplary Sequence Motifs For Endolysosomal Targeting Signal Motifs SEQ ID NO.

[0002] Attorney Docket No.: 45817-0174WO1 Signal Motifs SEQ ID NO. YSKV 86 us on oypept des The disclosure features fusion polypeptides comprising a first amino acid sequence (as discussed above) fused directly or via a linker to an endolysosomal targeting sequence (as discussed above). In some cases, the linker is a glycine serine linker. In one instance, the linker is G4S (SEQ ID NO: 141). In another instance, the linker is (G4S)n, where n = 2, 3, 4, 5, 6, 7, 8, 9, or 10 (SEQ ID NO: 142). In yet another case, the linker comprises or consists of the sequence of SEQ ID NO: 168. In other cases, the first amino acid sequence is fused directly to an endolysosomal targeting sequence. In one aspect, the first amino acid sequence of the fusion polypeptide comprises a T cell epitope (e.g., an immunodominant epitope), T cell epitopes, a subunit, or the entire antigen for tolerization (e.g., MOG, gliadin, a mitochondrial antigen E2 component of the 2-oxo dehydrogenase complex (e.g., PDC-E2). In some instances, the endolysosomal targeting sequence of these fusion polypeptides is or from a human MITD, a human LAMP (e.g., LAMP1, LAMP2, DC-LAMP), or a human CD74 protein. Attorney Docket No.: 45817-0174WO1 In some cases, the first amino acid sequence comprises or consists of a MOG amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to any one of the sequences of SEQ ID NO:33 to 42. In other cases, the first amino acid sequence comprises or consists of a gliadin amino acid sequence. In another case, the first amino acid sequence comprises or consists of a tissue transglutaminase sequence. In yet other cases, the first amino acid sequence comprises or consists of a PDC- E2 amino acid sequence, or a sequence of or from E3BP, OGDC-E2, PDC-E1a, or BCOADC-E2. In some cases, the above first amino acid sequence can be about 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, or 200 amino acids in length. In one instance, the fusion polypeptide comprises an endolysosomal targeting sequence comprising or consisting of any of the sequences set forth in SEQ ID NO: 29, 30, 31, 32, 49, 143, 144, or 145. In some cases, the endolysosomal targeting sequence comprises or consists of an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% identical to any of the sequences of SEQ ID NO: 29, 30, 31, 32, 49, 143, 144, or 145. In some instances, the fusion polypeptide comprises an endolysosomal targeting sequence with the sequence set forth in any one of SEQ ID NO: 29, 30, 31, 32, 49, 143, 144, or 145, with 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 amino acid substitutions. In certain instances, the fusion polypeptide comprises an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% identical, or 100% identical to the sequence: Attorney Docket No.: 45817-0174WO1 ISNIRRVIAQRLMQSKQTIPRRKRGDALCEIETDKAVVRRKRGDLIAEVETDKATV RRKRFDSICEVQSDKASVRRKRGDLLAEIETDKATIRRKRDEVVKEIETDKTSVR RKRENSMLIPIAVGGALAGLVLIVLIAYLVGRKRSHAGYQTI (SEQ ID NO:177) (wherein the sequence shown in bold lettering is the endolysosomal targeting sequence). In some cases, the fusion polypeptide comprises a signal sequence immediately upstream of the N-terminal “I” amino acid of SEQ ID NO: 177. In certain cases, the signal sequence comprises or consists of the sequence of SEQ ID NO:170. In some cases, the linkers used in SEQ ID NO:177 can be replaced by other peptide linkers. In some instances, the fusion polypeptide can be administered to a subject (e.g., human) in need thereof as a polypeptide. In other instances, the fusion polypeptide can be administered to a subject (e.g., human) in need thereof as an mRNA (e.g., formulated in a LNP). In one instance, the fusion polypeptide is administered to a subject (e.g., human) in need thereof as an mRNA formulated in a LNP. ImmunoModulatory Agents In certain cases, the antigen-specific immunotherapy (ASIT) involves administering to the subject (e.g., a human) in need thereof a fusion polypeptide described herein along with an immunomodulatory agent. This is particularly beneficial in instances where the antigen for tolerization has not undergone central tolerance and can be useful for peripheral induction of Tregs, suppression of effector T cell activation to drive anergy / non-responsiveness or deletion, or for enhancing Treg suppressive functionality with alternative routes of administration (e.g., intradermal, subcutaneous, or intramuscular routes of administration). The immunomodulatory agent can be administered before, at substantially the same time as, or after the administration of the ASIT to the subject. The immunomodulatory agent may be administered as a small molecule, a polypeptide, or as an mRNA (e.g., formulated in a four component or five component LNP as described in more detail herein) with the primary objective of modulating T cell signaling or modulating the antigen-presenting cells to prevent antigen presenting cell maturation. The immunomodulatory agent may be administered as a Attorney Docket No.: 45817-0174WO1 nucleic acid encoding the immunomodulator, a protein, or as a small molecule. The immunomodulatory agent may be administered before, at the same time as, or after administration of the fusion polypeptide (or a nucleic acid encoding the fusion polypeptide). Any immunomodulatory agent that can drive infectious tolerance can also be used (see e.g., Kenison JE, Stevens NA, Quintana FJ. Therapeutic induction of antigen- specific immune tolerance. Nat Rev Immunol.2024 May;24(5):338-357, especially Fig.2 and Table 1 (incorporated by reference herein)). In certain cases, the immunomodulatory agent drives infectious tolerance to the antigen to be tolerized in an antigen-independent manner. In some cases, the immunomodulatory agent drives infectious tolerance to the antigen to be tolerized in an antigen-specific manner. IL2 Mutein One example of an immunomodulatory agent that drives infectious tolerance to the antigen to be tolerized in an antigen-independent manner is an IL2 mutant protein (mutein). In some cases, the IL-2 muteins have decreased CD122 affinity (relative to wild type IL-2) and represent one approach for increasing CD25 dependence and enhancing Treg cell-selectivity. Examples of an IL2 mutein that can be employed herein are described in de Picciotto et al., Nat Commun 2022 Jul 5;13(1):3866; Peterson et al., J. Autoimmun 95, 1–14 (2018); Khoryati et al., Sci Immunol.2020 Aug 14;5(50):eaba5264; and PCT / US2020 / 55844 (5’ UTR: SEQ ID NO: 26; 3’ UTR: SEQ ID NO: 27; ORF1: SEQ ID NO: 11; ORF2: SEQ ID NO: 36; the entire sequence represented by SEQ ID NO: 37 (see, e.g., Table 4A) – note that all SEQ ID NOs in this parenthesis refer to those in the referenced PCT application) (all incorporated by reference herein in their entirety). In some instances, the IL-2 mutein is an IgG-(IL-2 N88D)2molecule. The molecules consist of a human IgG1 with V-domain germline sequences and an Attorney Docket No.: 45817-0174WO1 engineered short VH CDR3 that has no known antigen-binding properties on human cells or tissues. Specific point mutations in the Fc-portion of the IgG1 (P329G, L234A, L235A) render it effector silent by abolishing C1q and FcRγ binding while leaving normal FcRn function intact. Each IgG1 was engineered to have one or two N88D mutein human IL-2 molecules covalently fused at their N-terminal amino acid to the C-terminus of one or both of the IgG1 heavy chains (omitting the C-terminal lysine) via a flexible (G4S)3 (SEQ ID NO: 146)-peptide linker, i.e. IgG-(IL-2 N88D)2. In certain instances, the IL2 mutein that can be employed herein is one described in US 9,546,203, US 9,732,134, US 10,174,091, US 10,035,836, or US 11,077,172 (each of which is incorporated by reference herein). In other instances, the immunomodulatory agent is a CD25 biased IL2 compound described in Table 2 of Raeber et al., eBioMedicine 2023;90: 104539 (incorporated by reference herein). In one instance, the IL2 mutein is human IL2.V69A.Q74P.N88D and comprises the following amino acid sequence: SAPTSSSTKKTQLQLEHLLLDLQMILNGINNYKNPKLTRMLTFKFYMPKKATELKHLQCLEEELK PLEEALNLAPSKNFHLRPRDLISDINVIVLELKGSETTFMCEYADETATIVEFLNRWITFCQSII STLT (SEQ ID NO:158). In some instances, the IL2 mutein comprises an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the sequence of SEQ ID NO:158. In one instance, the IL2 mutein is included in a HSA fusion, specifically, HSA- human IL2.V69A.Q74P.N88D, the mRNA and amino acid sequences of which are provided below. In some instances, the IL2 mutein comprises an amino acid sequence that is at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the sequence of SEQ ID NO:156. In certain instances, the IL-2 mutein is encoded by the mRNA sequence comprising a nucleic acid sequence that is at least 80%, Attorney Docket No.: 45817-0174WO1 at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical to the sequence of SEQ ID NO:157. In one instance, the IL-2 mutein is encoded by an mRNA sequence comprising the nucleic acid sequence of SEQ ID NO:157. In some cases, the mRNA further comprises a 5’UTR and a 3’UTR. In some cases, the 5’UTR comprises the sequence of SEQ ID NO:15. In some cases, the 3’UTR comprises the sequence of SEQ ID NO:16. In some cases, a delivery vehicle (e.g., a nanoparticle such as a LNP) can be formulated with both a polynucleotide encoding a fusion polypeptide described herein and a polynucleotide encoding an IL2 mutein described herein. In other cases, two separate delivery vehicles (e.g., a nanoparticle such as a LNP) can be used, one for a polynucleotide encoding a fusion polypeptide described herein and one for a polynucleotide encoding an IL2 mutein described herein. mRNA sequence AUGAAGUGGGUGACAUUCAUCAGCCUGCUCUUCCUGUUCAGCAGCGCCUAUAGCCGCG GCGUAUUCCGGCGGGACGCCCAUAAGAGCGAGGUGGCCCAUCGGUUCAAGGACCUGGG CGAGGAGAACUUCAAGGCAUUGGUCCUGAUCGCUUUCGCCCAGUACUUGCAGCAGUGC CCCUUCGAGGACCACGUGAAGCUCGUAAACGAGGUCACCGAGUUUGCAAAGACCUGCG UGGCCGACGAGAGCGCCGAGAAUUGCGACAAGAGCCUGCACACCCUGUUCGGCGACAA GCUGUGUACUGUGGCCACCCUGCGGGAAACAUACGGCGAGAUGGCCGACUGCUGCGCC AAGCAGGAGCCCGAGCGGAACGAGUGUUUCCUGCAGCACAAGGACGACAACCCCAACC UGCCCCGGCUUGUUCGGCCUGAGGUAGACGUUAUGUGUACAGCUUUCCACGACAACGA GGAGACAUUCCUGAAGAAGUACCUGUACGAGAUCGCCCGGCGUCAUCCCUACUUCUAC GCCCCUGAGCUGCUGUUCUUCGCCAAACGGUACAAGGCCGCAUUCACAGAGUGCUGUC AGGCUGCCGAUAAGGCCGCCUGCCUGCUGCCUAAGCUGGACGAGCUGCGGGACGAAGG CAAGGCAAGCAGCGCUAAGCAGCGGCUGAAGUGUGCCAGCCUGCAGAAGUUCGGGGAG CGGGCCUUCAAAGCCUGGGCAGUGGCCCGGCUGAGCCAGCGGUUCCCCAAGGCAGAGU UCGCAGAGGUAAGCAAGUUGGUGACCGACCUGACCAAAGUGCACACCGAGUGUUGCCA CGGCGACCUGCUGGAGUGCGCUGACGACCGGGCCGACCUGGCUAAGUACAUUUGUGAG AACCAAGACAGCAUCAGCAGCAAACUGAAGGAGUGCUGCGAGAAGCCCCUGUUGGAGA AGAGCCACUGCAUCGCCGAGGUGGAGAACGACGAGAUGCCCGCCGAUCUGCCCAGCCU GGCCGCCGACUUCGUGGAGAGCAAGGACGUUUGCAAGAACUACGCCGAAGCAAAGGAC GUGUUCCUGGGGAUGUUUCUUUACGAAUACGCUCGGCGGCAUCCUGACUACAGCGUGG UUCUGUUACUGCGGCUGGCCAAGACUUACGAGACAACCCUGGAGAAGUGUUGCGCCGC AGCGGAUCCCCACGAGUGCUACGCCAAGGUGUUCGACGAGUUCAAGCCCCUUGUGGAG GAGCCCCAGAACCUGAUCAAGCAGAACUGCGAGCUGUUCGAGCAGUUGGGAGAGUACA AGUUCCAGAACGCCCUGCUGGUGCGGUAUACAAAGAAGGUGCCCCAAGUGAGCACACC CACCCUGGUGGAGGUGAGCCGGAACCUGGGCAAGGUGGGCAGUAAGUGCUGUAAGCAC CCCGAGGCCAAGCGGAUGCCCUGCGCCGAGGACUACCUGAGCGUGGUGCUGAACCAGC Attorney Docket No.: 45817-0174WO1 UGUGCGUACUGCACGAGAAGACGCCCGUGAGCGACCGGGUGACCAAGUGUUGUACCGA sequence of SEQ ID NO:158 is linked at its C-terminus to a human IgG hinge + CH2+CH3 region. In some cases, the IL2 mutein (e.g., SEQ ID NO:158) is linked to a half-life extension moiety (e.g., a VHH that specifically binds to HSA). The half-life extension moiety may be linked at the N- or C-terminus of the sequence of SEQ ID NO:158. Attorney Docket No.: 45817-0174WO1 In some instances, the above-described IL2 mutein(s) are administered as a polypeptide. In other instances, the above-described IL2 mutein(s) are administered as an mRNA (e.g., formulated in a LNP). See, e.g., PCT / US2020 / 55844 incorporated by reference herein. Treg Epitopes Infectious tolerance refers to a phenomenon where a tolerance-inducing state is transferred from one cell population to another. More specifically, this occurs when a Treg is engaged with an antigen presenting cell (APC) that is co-engaged with a T cell recognizing the antigen of interest. The engaged Treg maintains the APC in a tolerogenic state and secretes anti-inflammatory cytokines that favor additional Treg development and prevent effector T cell responses. See e.g., Gravano, Cell Mol Life Sci.2012 Jun; 69(12): 1997–2008. One example of an immunomodulatory agent that drives infectious tolerance to the antigen to be tolerized in an antigen-specific or tissue-specific manner is a Treg epitope. Non-limiting examples of such Treg epitopes that can be employed include sequences comprising or consisting of the amino acid sequences provided in Table 2 below. Table 2. Sequences of Exemplary Treg epitopes. Treg Sequence SEQ ID NO Attorney Docket No.: 45817-0174WO1 P52960 WLSIISMATLESSLK 218 n some nstances, t e reg ep tope(s) can be n ed at t e – and / or C-terminal of a fusion polypeptide described herein. In certain cases, the Treg epitope is any one of those set forth in SEQ ID NOs.: 43-48 or 213-220. In certain cases, polynucleotides encoding such Treg epitope linked fusion polypeptides are employed. In some cases, the polynucleotides are formulated in a delivery vehicle such as a nanoparticle (e.g., LNP such as LNP1 or LNP A, B, C, D, or E). mTOR Inhibitors To prevent antigen presenting cell maturation and regulate interaction with T cells to favor Treg induction and inhibit effector T cell activation, an mTOR inhibitor can be used. In some instances, these mTOR inhibitors can be mRNA encoded and delivered simultaneous, prior to, or after delivering the antigen. Examples of mTOR inhibitors are PRAS40, DEPTOR, and MORG1. These mTOR inhibitor sequences are highly conserved between species. Examples of mRNA and amino acid sequences of several Attorney Docket No.: 45817-0174WO1 human mTOR inhibitors are provided below along with non-limiting examples of 5’ and 3’ UTRs that can be used in the mRNAs. Human PRAS40 mRNA AUGGCCAGCGGACGGCCAGAGGAGCUGUGGGAAGCCGUGGUAGGCGCCGCCGAACGGU Attorney Docket No.: 45817-0174WO1 GCUGCAGCGAGGACGGUAAGGUGUUCUUCUGGGACCUGGUGGAGGGCGCACUGGCCUU Attorney Docket No.: 45817-0174WO1 Acid VQEGEATTRKEAEQLCHRLMEHGIIQHVSNKHPFVDSNLLYQFRMNFRRRRRLMELLN Sequence EKSPSSQETHDSPFCLRKQSHDNRKSTSFMSVSPSKEIKIVSAVRRSSMSSCGSSGYF SSSPTLSSSPPVLCNPKSVLKRPVTSEELLTPGAPYARKTFTIVGDAVGWGFVVRGSK PCHIQAVDPSGPAAAAGMKVCQFVVSVNGLNVLHVDYRTVSNLILTGPRTIVMEVMEE LEC(SEQ ID NO:164) 5’ UTR AGGAAAUCGCAAAAUUUGCUCUUCGCGUUAGAUUUCUUUUAGUUUUCUCGCAACUAGC sequence AAGCUUUUUGUUCUCGCC (SEQ ID NO:15) 3’ UTR UAAAGCUCCCCGGGGGCCUCGGUGGCCUAGCUUCUUGCCCCUUGGGCCUCCCCCCAGC Sequence CCCUCCUCCCCUUCCUGCACCCGUACCCCCGUGGUCUUUGAAUAAAGUCUGAGUGGGC GGC (SEQ ID NO:16) In some instances, the mRNA that is employed as an immunomodulator encodes an mTOR inhibitor that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to any one of SEQ ID NOs.: 160, 162, or 164. In certain instances, an mRNA encoding a mTOR inhibitor described above that is employed as an immunomodulator comprises a nucleic acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to any one of SEQ ID NOs.: 159, 161, or 163. In some cases, an mRNA encoding a mTOR inhibitor described above that is employed as an immunomodulator comprises a mRNA sequence from 5’ to 3’ as follows: SEQ ID NO:15 followed by SEQ ID NO:159 followed by SEQ ID NO: 16; or SEQ ID NO:15 followed by SEQ ID NO:161 followed by SEQ ID NO: 16; or SEQ ID NO:15 followed by SEQ ID NO:163 followed by SEQ ID NO: 16. In some cases, such mRNAs are co-formulated with an mRNA encoding a fusion polypeptide described herein in a delivery vehicle such as a nanoparticle (e.g., a LNP). In other instances two separate delivery vehicles are used, one for the mRNA that encodes the mTOR inhibitor and another for the mRNA that encodes a fusion polypeptide described herein. Activators of TGFβ TGFβ is a potent pleiotropic cytokine that is critical for peripheral induction of FOXP3+ Tregs. TGFβ circulates in a latent complex and needs to be activated for it to be Attorney Docket No.: 45817-0174WO1 biologically active. Integrin beta 6 (ITB6) and integrin beta 8 (ITB8) are two transmembrane domain proteins capable of activating TGFβ. In some instances, (ITB6) and / or integrin beta 8 (ITB8) can be used to induce FOXP3 expression. Polynucleotides encoding Integrin beta 6 are described in WO2023 / 077170 (PCT / US2022 / 79095), which is incorporated by reference in its entirety. In some instances, a polynucleotide comprising an mRNA which encodes an ITB6 can be used as an immunomodulator. In some cases, an mRNA which encodes an ITB6 comprises a nucleotide sequence encoding an amino acid sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO:185. In other cases, an mRNA which encodes an ITB6 comprises a nucleotide sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO:184. In some cases, these mRNAs include a 5’ and 3’ UTR comprising the sequence set forth in SEQ ID NOs.: 15 and 186, respectively. In certain instances, a lipid nanoparticle (LNP) composition comprising a polynucleotide comprising an mRNA which encodes an ITB6 is used. In certain instances, a polynucleotide comprising an mRNA which encodes an ITB8 can be used as an immunomodulator. In some cases, an mRNA which encodes an ITB8 comprises a nucleotide sequence encoding an amino acid sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO:182. In other cases, an mRNA which encodes an ITB8 comprises a nucleotide sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO:181. In some cases, these mRNAs include a 5’ and 3’ UTR comprising the sequence set forth in SEQ ID NOs.: 15 and 183, respectively. In some instances, a lipid nanoparticle (LNP) composition comprising a polynucleotide comprising an mRNA which encodes an ITB8 is used. In some cases, such mRNAs are co-formulated with an mRNA encoding a fusion polypeptide described herein in a Attorney Docket No.: 45817-0174WO1 delivery vehicle such as a nanoparticle (e.g., a LNP). In other instances, two separate delivery vehicles are used, one for the mRNA that encodes the activator of TGFβ (e.g., ITB6 or ITB8) and another for the mRNA that encodes a fusion polypeptide described herein. Integrin Beta 8 Attorney Docket No.: 45817-0174WO1 GUGCACCCGGGCCGUCACCUACCGGCGGGAGAAGCCCGAGGAGAUCAAGAUGGACAUC UCCAAACUGAACGCCCAGGAAGCCUUCCGGUGCAACUUCGGCAAGCCAAUCCCUAAUC CCCUGCUGGGCCUGGACAGCACC(SEQ ID NO:181) Encoded MCGSALAFLTAALLSLHNCQRGPALVLGAAWVFSLVLGLGQSEHNRCGSANVVSCARC Amino LQLGPECGWCVQEDFVSGGSGSERCDTVSSLISKGCPVDSIEYLSVHVVTSSENEINT Acid QVTPGEVSVQLHPGAEANFMLKVRPLKKYPVDLYYLVDVSASMHNNIEKLNSVGNDLS Sequence KKMALYSRDFRLGFGSYVDKTVSPYISIHPERIHNQCSDYNLDCMPPHGYIHVLSLTE NITEFEKAVHRQKISGNIDTPEGGFDAMLQAAVCESHIGWRKEAKRLLLVMTDQTSHL ALDSKLAGIVVPNDGNCHLKNNVYVKSTTMEHPSLGQLSEKLIDNNINVIFAVQGKQF HWYKDLLPLLPGAIAGEIESKAANLNNLVVEAYKKIISEVKVQLENQVHGVHFNITAI CPDGARKPGISGCGNVTSNDEVLFNVTVVMKTCDIMGGKNYAIIKPIGFNETTKVHIH RSCSCQCENHRGLKGQCAEAAPDPKCPQCDDSRCHFDEDQFPSETCKPQEDQPVCSGR GVCICGKCLCHKTKLGRVYGQYCEKDDFSCPYLHGDVCAGHGECEGGRCQCFSGWEGD RCQCPSASAQHCVNSKGQVCSGRGTCVCGRCECTDPRSIGRLCEHCPTCHLSCSENWN CLQCLHPHNLSQAALDQCKSSCAVMEQHRMDQTSECLSGPSYLRIFFIIFIVTFLIGL LKVLIIRQVILQWNNNKIKSSSDYRMSASKKDKLILQSVCTRAVTYRREKPEEIKMDI SKLNAQEAFRCNFGKPIPNPLLGLDST (SEQ ID NO:182) 5’ UTR AGGAAAUCGCAAAAUUUGCUCUUCGCGUUAGAUUUCUUUUAGUUUUCUCGCAACUAGC sequence AAGCUUUUUGUUCUCGCC(SEQ ID NO:15) 3’ UTR UAAAGCUCCCCGGGGCAAACACCAUUGUCACACUCCAGCCUCGGUGGCCUAGCUUCUU Sequence GCCCCUUGGGCCCAAACACCAUUGUCACACUCCAUCCCCCCAGCCCCUCCUCCCCUUC CUGCACCCGUACCCCCCAAACACCAUUGUCACACUCCAGUGGUCUUUGAAUAAAGUCU GAGUGGGCGGC(SEQ ID NO:183) Integrin Beta 6 mRNA AUGGGUAUCGAGCUGCUGUGUCUGUUCUUUCUGUUUCUGGGCCGCAACGACCACGUCC sequence AGGGCGGCUGCGCCCUGGGCGGGGCCGAGACCUGCGAGGACUGCCUGCUCAUCGGGCC ACAGUGUGCCUGGUGUGCACAGGAGAACUUCACCCACCCCAGCGGGGUGGGCGAGAGG UGCGACACCCCUGCAAAUCUGCUGGCAAAGGGCUGCCAGCUGAAUUUCAUCGAGAAUC CCGUCAGCCAGGUGGAGAUUCUCAAGAACAAGCCUCUGAGCGUCGGACGGCAGAAGAA CUCUUCUGACAUCGUCCAGAUCGCACCUCAGAGCCUGAUUCUGAAGCUCCGCCCAGGC GGAGCUCAGACCCUCCAGGUCCACGUCAGGCAGACUGAGGACUACCCCGUGGACCUGU ACUACCUGAUGGAUCUGUCCGCCAGCAUGGACGACGAUCUGAACACCAUUAAGGAGCU GGGCAGCCGGCUCUCUAAGGAGAUGUCCAAGCUCACCAGCAACUUCAGGCUGGGAUUC GGCAGCUUUGUCGAGAAGCCUGUGUCUCCUUUCGUGAAGACCACACCAGAGGAGAUCG CAAACCCCUGUAGCAGCAUCCCCUACUUCUGCCUGCCUACAUUCGGGUUCAAGCACAU UCUGCCUCUGACCAACGACGCAGAGCGCUUUAACGAGAUCGUGAAGAAUCAGAAGAUC AGCGCCAACAUUGAUACUCCUGAGGGCGGCUUCGACGCCAUCAUGCAGGCUGCCGUCU GCAAGGAGAAGAUCGGGUGGAGGAACGACAGCCUCCACCUGCUCGUGUUCGUGAGCGA CGCCGACAGCCACUUUGGGAUGGACUCCAAGCUGGCCGGCAUCGUGAUCCCCAACGAC GGGCUGUGUCACCUCGAUUCCAAGAACGAGUACAGCAUGAGCACCGUGCUGGAGUACC CCACCAUUGGGCAGCUCAUUGAUAAGCUCGUGCAGAACAACGUCCUGCUGAUCUUUGC Attorney Docket No.: 45817-0174WO1 AGUGACACAGGAGCAGGUGCACCUGUACGAGAAUUACGCAAAGCUCAUCCCCGGAGCC ACUGUGGGCCUCCUGCAGAAGGACUCCGGGAACAUCCUCCAGCUCAUCAUCUCCGCCU ACGAGGAGCUGAGGAGCGAGGUGGAGCUCGAGGUCCUCGGGGACACCGAGGGCCUCAA CCUGAGCUUUACCGCCAUCUGCAACAACGGAACUCUCUUCCAGCACCAGAAGAAGUGC UCUCACAUGAAGGUGGGCGACACCGCCUCCUUCAGCGUGACCGUGAACAUCCCUCACU GUGAGCGGCGGAGCCGCCACAUCAUCAUCAAGCCCGUGGGGCUCGGGGACGCCCUGGA GCUCCUGGUGUCCCCUGAGUGUAACUGCGACUGCCAGAAGGAGGUCGAGGUGAACAGC UCUAAGUGCCACCACGGCAACGGGAGCUUCCAGUGCGGGGUGUGCGCAUGCCACCCCG GCCACAUGGGGCCUCGCUGCGAGUGCGGCGAGGACAUGCUGUCUACCGACAGCUGCAA GGAGGCCCCUGACCACCCUAGCUGCUCUGGCCGCGGAGACUGCUACUGCGGCCAGUGC AUCUGCCACCUGUCCCCUUACGGGAACAUUUACGGGCCCUACUGCCAGUGUGAUAACU UUUCCUGCGUGCGGCACAAGGGCCUGCUGUGCGGAGGAAAUGGCGACUGCGACUGCGG CGAGUGCGUCUGUCGCAGCGGCUGGACCGGGGAGUACUGCAACUGCACUACUUCCACU GACAGCUGUGUCAGCGAGGACGGGGUGCUCUGUUCUGGCCGCGGGGACUGCGUCUGCG GCAAGUGCGUGUGCACUAAUCCAGGGGCCUCCGGGCCCACCUGCGAGCGGUGUCCCAC CUGCGGGGACCCUUGCAACAGCAAGAGGUCCUGCAUCGAGUGCCACCUGUCCGCCGCC GGACAGGCACGCGAGGAGUGCGUCGAUAAGUGUAAGCUCGCCGGAGCUACAAUUAGCG AGGAGGAGGACUUCUCCAAGGACGGGAGCGUGAGCUGCUCCCUCCAGGGAGAGAACGA GUGCCUGAUCACUUUCCUCAUCACCACUGAUAACGAGGGAAAGACAAUCAUUCACUCU AUCAACGAGAAGGAUUGUCCCAAGCCCCCAAACAUUCCCAUGAUCAUGCUGGGAGUGU CCCUGGCAAUCCUGCUGAUCGGAGUCGUGCUGCUCUGCAUCUGGAAGCUGCUCGUCUC CUUCCACGACCGCAAGGAGGUCGCAAAGUUUGAGGCCGAGCGGUCUAAGGCCAAGUGG CAGACAGGGACCAAUCCUCUCUACCGCGGGUCUACUUCUACCUUCAAGAACGUGACUU ACAAGCACAGGGAGAAGCAGAAGGUGGACCUCUCCACCGAUUGC(SEQ ID NO:184) Encoded MGIELLCLFFLFLGRNDHVQGGCALGGAETCEDCLLIGPQCAWCAQENFTHPSGVGER Amino CDTPANLLAKGCQLNFIENPVSQVEILKNKPLSVGRQKNSSDIVQIAPQSLILKLRPG Acid GAQTLQVHVRQTEDYPVDLYYLMDLSASMDDDLNTIKELGSRLSKEMSKLTSNFRLGF Sequence GSFVEKPVSPFVKTTPEEIANPCSSIPYFCLPTFGFKHILPLTNDAERFNEIVKNQKI SANIDTPEGGFDAIMQAAVCKEKIGWRNDSLHLLVFVSDADSHFGMDSKLAGIVIPND GLCHLDSKNEYSMSTVLEYPTIGQLIDKLVQNNVLLIFAVTQEQVHLYENYAKLIPGA TVGLLQKDSGNILQLIISAYEELRSEVELEVLGDTEGLNLSFTAICNNGTLFQHQKKC SHMKVGDTASFSVTVNIPHCERRSRHIIIKPVGLGDALELLVSPECNCDCQKEVEVNS SKCHHGNGSFQCGVCACHPGHMGPRCECGEDMLSTDSCKEAPDHPSCSGRGDCYCGQC ICHLSPYGNIYGPYCQCDNFSCVRHKGLLCGGNGDCDCGECVCRSGWTGEYCNCTTST DSCVSEDGVLCSGRGDCVCGKCVCTNPGASGPTCERCPTCGDPCNSKRSCIECHLSAA GQAREECVDKCKLAGATISEEEDFSKDGSVSCSLQGENECLITFLITTDNEGKTIIHS INEKDCPKPPNIPMIMLGVSLAILLIGVVLLCIWKLLVSFHDRKEVAKFEAERSKAKW QTGTNPLYRGSTSTFKNVTYKHREKQKVDLSTDC (SEQ ID NO:185) 5’ UTR AGGAAAUCGCAAAAUUUGCUCUUCGCGUUAGAUUUCUUUUAGUUUUCUCGCAACUAGC sequence AAGCUUUUUGUUCUCGCC(SEQ ID NO:15) 3’ UTR UAAGCCCCUCCGGGGCAAACACCAUUGUCACACUCCAGCCUCGGUGGCCUAGCUUCUU Sequence GCCCCUUGGGCCCAAACACCAUUGUCACACUCCAUCCCCCCAGCCCCUCCUCCCCUUC Attorney Docket No.: 45817-0174WO1 CUGCACCCGUACCCCCCAAACACCAUUGUCACACUCCAGUGGUCUUUGAAUAAAGUCU GAGUGGGCGGC (SEQ ID NO:186) In some instances, the mRNA that is employed as an immunomodulator encodes an activator of TGFβ that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to SEQ ID NO.: 182 or 185. In certain instances, an mRNA encoding an activator of TGFβ described above that is employed as an immunomodulator comprises a nucleic acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to SEQ ID NO.: 181 or 184. In some cases, an mRNA encoding an activator of TGFβ described above that is employed as an immunomodulator comprises a mRNA sequence from 5’ to 3’ as follows: SEQ ID NO:15 followed by SEQ ID NO:181 followed by SEQ ID NO: 183 or 186; or SEQ ID NO:15 followed by SEQ ID NO:184 followed by SEQ ID NO: 183 or 186. In some cases, such mRNAs are co-formulated with an mRNA encoding a fusion polypeptide described herein in a delivery vehicle such as a nanoparticle (e.g., a LNP). In other instances, two separate delivery vehicles are used, one for the mRNA that encodes the activator of TGFβ and another for the mRNA that encodes a fusion polypeptide described herein. Nucleic Acids, Vectors, Host Cells, and Methods of Making The disclosure features a polynucleotide comprising a nucleic acid encoding a fusion polypeptide described herein. In some instances, the nucleic acid is an mRNA. In some instances, the mRNA is a modified mRNA. In certain cases, all uracils in the polynucleotide and / or mRNA are N-1-methylpseudouracil. Also provided are vectors comprising the above nucleic acids. Such vectors can include regulatory regions that direct expression in a cell of choice. Host cells comprising the nucleic acids or vectors are also encompassed by this disclosure. The host cells may be a bacterial, fungal, insect, or mammalian cell. In some cases, the host cell is a human cell. Attorney Docket No.: 45817-0174WO1 The disclosure also encompasses methods of making the fusion polypeptides of the disclosure. In some cases, the host cells are cultured under conditions that promote the expression of the fusion polypeptide. In some instances, the mRNA is vitro translation generated and has reduced dsRNA content. In some instances, the mRNA employed in this disclosure is synthetic and not in vitro translation (IVT)-derived mRNA. See, e.g., Dousis et al., Nature Biotechnology, Volume 41, April 2023, 560–568 (incorporated by reference herein). Polynucleotides and Open Reading Frames (ORFs) This disclosure features mRNAs for use in tolerizing a subject (e.g., human) in need thereof to selectively control antigen-specific effector T cell responses and promote or restore tolerance in the subject against that antigen. The mRNAs featured herein are administered to subjects and encode a fusion polypeptide described herein in vivo. As described above, the fusion polypeptide comprises an antigen to be tolerized and an endolysosomal targeting sequence. The antigen to be tolerized can be a foreign antigen or a self-antigen. In some cases, the antigen is an autoantigen, an allergen, or a protein therapeutic (e.g., antibody, a protein replacement therapy). The antigen can be a single epitope of the antigen (e.g., an immunodominant epitope), a string of epitopes, a shuffled epitope, a subunit of an antigen, a partial antigen sequence, or a full antigen sequence. In some cases, the endolysosomal targeting sequence is a sequence from human LAMP1, human LAMP2, human DC-LAMP, human CD74, or human MITD. The disclosure relates to polynucleotides, e.g., mRNA, comprising an open reading frame (ORF) of linked nucleosides encoding a fusion polypeptide described herein. In particular, the disclosure provides polynucleotides (e.g., sequence optimized polynucleotides) comprising nucleotides encoding a fusion polypeptide described herein. In some instances, the polynucleotide (e.g., a RNA, e.g., an mRNA) of the disclosure comprises a nucleotide sequence (e.g., an ORF) that encodes an antigen of interest (e.g., a human MOG protein described herein) fused to an endolysosomal Attorney Docket No.: 45817-0174WO1 targeting sequence. In some cases, the endolysosomal targeting sequence is a sequence from human LAMP1, human LAMP2, human DC-LAMP, human CD74, or human MITD. In certain cases, the nucleotide sequence encodes a polypeptide that comprises a sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identical to any one of SEQ ID NOs: 33 to 35. In some cases, the polynucleotide (e.g., a RNA, e.g., an mRNA) of the disclosure comprises a nucleotide sequence (e.g., an ORF) that encodes a human MOG protein of any one of SEQ ID NOs: 33 to 35 with 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 amino acid substitutions. In some cases, the polynucleotide (e.g., a RNA, e.g., an mRNA) of the disclosure comprises a sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identical to SEQ ID NO:25 but without the first 75 nucleotides of SEQ ID NO:25. In other cases, the polynucleotide (e.g., a RNA, e.g., an mRNA) of the disclosure comprises a sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identical to SEQ ID NO:25. In certain cases, the polynucleotide comprises a sequence of SEQ ID NOs: 25 with 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 nucleic acid substitutions. In some instances, the polynucleotide (e.g., a RNA, e.g., an mRNA) of the disclosure comprises a nucleotide sequence (e.g., an ORF) that encodes a first amino acid sequence (e.g., derived from a PBC-associated protein described herein such as PDC-E2, E3P, BCOAC-E2, OGDC-E2) fused to an endolysosomal targeting sequence. In some cases, the first amino acid sequence comprises one or more of SEQ ID NOS.: 171 to 176. In some cases, the endolysosomal targeting sequence is a sequence from human LAMP1, human LAMP2, human DC-LAMP, human CD74, or human MITD. In certain cases, the nucleotide sequence comprises a sequence that encodes a polypeptide that comprises a sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence Attorney Docket No.: 45817-0174WO1 identical to any one of SEQ ID NOs: 169, 177, or 166. In some cases, the polynucleotide (e.g., a RNA, e.g., an mRNA) of the disclosure comprises a nucleotide sequence (e.g., an ORF) that encodes a polypeptide of any one of SEQ ID NOs.: 169, 177, or 166 with 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 amino acid substitutions. In some cases, the polynucleotide (e.g., a RNA, e.g., an mRNA) of the disclosure comprises a sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identical to SEQ ID NO:165. In certain cases, the polynucleotide (e.g., a RNA, e.g., an mRNA) of the disclosure comprises a sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% sequence identical to SEQ ID NO:165 but without the first 72 nucleotides of SEQ ID NO:165. In certain cases, the polynucleotide comprises a sequence of SEQ ID NOs: 165 with 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 nucleic acid substitutions. In some instances, the polynucleotide of the disclosure (e.g., an RNA, e.g., an mRNA) comprises a nucleotide sequence (e.g., an ORF, e.g., SEQ ID NO:25 or 165) encoding a fusion polypeptide described herein further comprises a 5′-UTR (e.g., SEQ ID NO:8 or 15) and a 3′-UTR (e.g., SEQ ID NO:9, SEQ ID NO:16, or 167). In certain cases, the polynucleotide (e.g., a RNA, e.g., an mRNA) comprises a 5′ terminal cap (e.g., m7Gp-ppGm, m7Gp-ppGm-A, Cap0, Cap1, ARCA, inosine, N1-methyl-guanosine, 2′- fluoro-guanosine, 7-deaza-guanosine, 8-oxo-guanosine, 2-amino-guanosine, LNA- guanosine, 2-azidoguanosine, Cap2, Cap4, 5′ methylG cap, or an analog thereof) and a poly A-tail region (e.g., about 100 nucleotides in length). In some cases, the mRNA comprises a poly A tail. In some instances, the poly A tail is protected (e.g., with an inverted deoxy-thymidine). In some instances, the poly A tail comprises A100-UCUAG- A20-inverted deoxy-thymidine (SEQ ID NO: 211). In some instances, the poly A tail is A100-UCUAG-A20-inverted deoxy-thymidine (SEQ ID NO: 211). Attorney Docket No.: 45817-0174WO1 In some instances, the polynucleotide (e.g., a RNA, e.g., an mRNA) comprises a nucleotide sequence (e.g., an ORF) encoding a fusion polypeptide of this disclosure is single stranded or double stranded. In some instances, the polynucleotide comprising a nucleotide sequence (e.g., an ORF) encoding fusion polypeptide described herein is DNA or RNA. In some cases, the polynucleotide of the disclosure is RNA. In some cases, the polynucleotide of the disclosure is, or functions as, an mRNA. In some cases, the mRNA comprises a nucleotide sequence (e.g., an ORF) that encodes a fusion polypeptide described here in, and is capable of being translated to produce the fusion protein described herein in vitro, in vivo, in situ or ex vivo. In some cases, the polynucleotide of the disclosure (e.g., a RNA, e.g., an mRNA) comprises a sequence-optimized nucleotide sequence (e.g., an ORF) encoding a fusion protein described herein, wherein the polynucleotide comprises at least one chemically modified nucleobase, e.g., N1-methylpseudouracil or 5-methoxyuracil. In certain cases, all uracils in the polynucleotide are N1-methylpseudouracils. In other cases, all uracils in the polynucleotide are 5-methoxyuracils. In some cases, the polynucleotide further comprises a miRNA binding site, e.g., a miRNA binding site that binds to miR-142 and / or a miRNA binding site that binds to miR-126 and / or a miRNA binding site that binds to miR-122. By combining two or more different miRNA binding sites in an mRNA of this disclosure, one can turn on expression of the mRNA in some cells and turn off expression of the mRNA in other types of cells. In some cases, the polynucleotide further comprises a miR-122 binding site and a miR-126 binding site. Such a combination avoids the mRNA being expressed in hepatocytes and epithelial cells. In some cases, the polynucleotide (e.g., a RNA, e.g., an mRNA) disclosed herein is formulated with a delivery agent. In some cases, the delivery agent (e.g., LNP) comprises an ionizable amino lipid, a phospholipid, a structural lipid, and a PEG lipid with a mole ratio in the range of about (i) 40-50 mole ratio% ionizable amino lipid, optionally 45-50 mole ratio% ionizable amino lipid, for example, 45-46 mole ratio%, 46- 47 mole ratio%, 47-48 mole ratio%, 48-49 mole ratio%, or 49-50 mole ratio% for Attorney Docket No.: 45817-0174WO1 example about 45 mole ratio%, 45.5 mole ratio%, 46 mole ratio%, 46.5 mole ratio%, 47 mole ratio%, 47.5 mole ratio%, 48 mole ratio%, 48.5 mole ratio%, 49 mole ratio%, or 49.5 mole ratio%; (ii) 30-45 mole ratio% sterol (e.g., cholesterol), optionally 35-42 mole ratio% sterol, for example, 30-31 mole ratio%, 31-32 mole ratio%, 32-33 mole ratio%, 33-34 mole ratio%, 35-35 mole ratio%, 35-36 mole ratio%, 36-37 mole ratio%, 37-38 mole ratio%, 38-39 mole ratio%, or 39-40 mole ratio%, or 40-42 mole ratio% sterol; (iii) 5-15 mole ratio% helper lipid (e.g., DSPC), optionally 10-15 mole ratio% helper lipid, for example, 5-6 mole ratio%, 6-7 mole ratio%, 7-8 mole ratio%, 8-9 mole ratio%, 9-10 mole ratio%, 10-11 mole ratio%, 11-12 mole ratio%, 12-13 mole ratio%, 13-14 mole ratio%, or 14-15 mole ratio% helper lipid; and (iv) 1-5% PEG lipid (e.g., PL-02; PEG-DMG), optionally 1-5 mole ratio% PEG lipid, for example 1.5 to 2.5 mole ratio%, 1-2 mole ratio%, 2-3 mole ratio%, 3-4 mole ratio%, or 4-5 mole ratio% PEG lipid. In other cases, the delivery agent (e.g., LNP) comprises a sialic acid lipid, an ionizable amino lipid, a phospholipid, a structural lipid, and a PEG lipid with a mole ratio in the range of about (i) 0.1 to 2 mole ratio% sialic acid lipid, optionally 0.2 to 1.2 mole ratio%, for example 0.0.2 mole ratio%, 0.3 mole ratio%, 0.4 mole ratio%, 0.5 mole ratio%, 0.6 mole ratio%, 0.7 mole ratio%, 0.8 mole ratio%, 0.9 mole ratio%, 1.0 mole ratio%, 1.1 mole ratio%, 1.2 mole ratio%; (ii) 40-50 mole ratio% ionizable amino lipid, optionally 45-50 mole ratio% ionizable amino lipid, for example, 45-46 mole ratio%, 46-47 mole ratio%, 47-48 mole ratio%, 48-49 mole ratio%, or 49-50 mole ratio% for example about 45 mole ratio%, 45.5 mole ratio%, 46 mole ratio%, 46.5 mole ratio%, 47 mole ratio%, 47.5 mole ratio%, 48 mole ratio%, 48.5 mole ratio%, 49 mole ratio%, or 49.5 mole ratio%; (iii) 30-45 mole ratio% sterol (e.g., cholesterol), optionally 35-42 mole ratio% sterol, for example, 30-31 mole ratio%, 31-32 mole ratio%, 32-33 mole ratio%, 33-34 mole ratio%, 35-35 mole ratio%, 35-36 mole ratio%, 36-37 mole ratio%, 37-38 mole ratio%, 38-39 mole ratio%, or 39-40 mole ratio%, or 40-42 mole ratio% sterol; (iv) 5-15 mole ratio% helper lipid (e.g., DSPC), optionally 10-15 mole ratio% helper lipid, for example, 5-6 mole ratio%, 6-7 mole ratio%, 7-8 mole ratio%, 8-9 mole ratio%, 9-10 mole ratio%, 10-11 mole ratio%, 11-12 mole ratio%, 12-13 mole ratio%, 13-14 mole ratio%, or 14-15 mole ratio% helper Attorney Docket No.: 45817-0174WO1 lipid; and (v) 1-5% PEG lipid (e.g., PL-02; PEG-DMG), optionally 1-5 mole ratio% PEG lipid, for example 1.5 to 2.5 mole ratio%, 1-2 mole ratio%, 2-3 mole ratio%, 3-4 mole ratio%, or 4-5 mole ratio% PEG lipid. In some cases, the sialic acid lipid is Compound 1 or Compound 9 or a salt thereof; the ionizable amino lipid is Compound I-18 or II-6 or a salt thereof; the phospholipid is DSPC; the structural lipid is cholesterol; and the PEG- lipid is PL-02. In certain cases, the LNP comprises about 47 mole ratio% ionizable amino lipid (e.g., Compound I-18 or II-6 or a salt thereof); about 11 mole ratio% of phospholipid (e.g., DSPC); about 39 ml % of structural lipid (e.g., cholesterol); about 2 or 2.5 mole ratio% of PEG-lipid (e.g., PL-02); and about 0.5 or 1 mole ratio% of sialic acid lipid (e.g., Compound 1 or 9, or a salt thereof). In some instances, a polynucleotide of the disclosure is an mRNA that comprises a 5′-terminal cap (e.g., Cap1, e.g., m7Gp-ppGm-A), a 5′UTR (e.g., SEQ ID NO: 8 or 16), an ORF sequence of SEQ ID NO:25 (with or without the first 75 nucleotides of SEQ ID NO:25), a 3′UTR (e.g., SEQ ID NO:9 or 16), and a poly A tail (e.g., about 100 nt in length), wherein all uracils in the polynucleotide are N1-methylpseudouracils. In some cases, the delivery agent comprises SA-V (e.g., Compound 1 or a salt thereof) or SA-VI (e.g., Compound 9 or a salt thereof) of this disclosure as the sialic acid lipid, Compound I-18 or Compound II-6 as the ionizable amino lipid and PL-02 as the PEG lipid. In some cases, the delivery agent comprises Compound I-18 as the ionizable amino lipid and PL- 02 as the PEG lipid. In some cases, the delivery agent comprises Compound I-18 as the ionizable amino lipid; PL-02 as the PEG lipid; Compound 1 as the sialic acid lipid; cholesterol as the structural lipid; and DSPC as the phospholipid. In some cases, the delivery agent comprises Compound I-18 as the ionizable amino lipid; PL-02 as the PEG lipid; Compound 9 as the sialic acid lipid; cholesterol as the structural lipid; and DSPC as the phospholipid. In certain cases, the delivery agent comprises Compound II-6 as the ionizable amino lipid; PL-02 as the PEG lipid; Compound 1 as the sialic acid lipid; cholesterol as the structural lipid; and DSPC as the phospholipid. In certain cases, the delivery agent comprises Compound II-6 as the ionizable amino lipid; PL-02 as the PEG lipid; Compound 9 as the sialic acid lipid; cholesterol as the structural lipid; and DSPC as Attorney Docket No.: 45817-0174WO1 the phospholipid. In certain cases, the delivery agent is an LNP. In some cases, the ionizable amino lipid is present in the LNP at about 47 mole ratio%; the phospholipid is present at about 11 mole ratio%; the structural lipid is present at about 39 mole ratio%; the PEG-lipid is present at about 2 mole ratio% or about 2.5 mole ratio%; and the sialic acid lipid is present at about 1 mole ratio% or about 0.5 mole ratio%. Signal Sequences The polynucleotides (e.g., a RNA, e.g., an mRNA) can also comprise nucleotide sequences that encode additional features that facilitate trafficking of the encoded polypeptides to therapeutically relevant sites. One such feature that aids in protein trafficking is the signal sequence, or targeting sequence. The peptides encoded by these signal sequences are known by a variety of names, including targeting peptides, transit peptides, and signal peptides. In some cases, the polynucleotide (e.g., a RNA, e.g., an mRNA) comprises a nucleotide sequence (e.g., an ORF) that encodes a signal peptide operably linked to a nucleotide sequence that encodes a fusion protein described herein. In some instances, the "signal sequence" or "signal peptide" is a polynucleotide or polypeptide, respectively, which is from about 30-210, e.g., about 45-80 or 15-60 nucleotides (e.g., about 20, 30, 40, 50, 60, or 70 amino acids) in length that, optionally, is incorporated at the 5′ (or N-terminus) of the coding region or the polypeptide, respectively. Addition of these sequences results in trafficking the encoded polypeptide to a desired site, such as the endoplasmic reticulum or the mitochondria through one or more targeting pathways. Some signal peptides are cleaved from the protein, for example by a signal peptidase after the proteins are transported to the desired site. Non-limiting examples of signal peptides are provided in Owji et al., European Journal of Cell Biology, 97(6):422-441 (2018); O’Neill et al., ACS Synth. Biol., 12, 8, 2339–2352 (2023). In certain instances, the polynucleotide of the disclosure comprises a nucleotide sequence encoding a fusion protein described herein, wherein the nucleotide sequence further comprises a 5′ nucleic acid sequence encoding a signal peptide. In some instances, the signal peptide is a heterologous signal peptide. Attorney Docket No.: 45817-0174WO1 In some cases, the signal peptide comprises any one of the following amino acid sequences: MLVMAPRTVLLLLSAALALTETWAG (SEQ ID NO:27),MRVTAPRTLILLLSGALALTETWA (SEQ ID NO:28),MLKNKKFKLNFIALTVAYALAPYTEA (SEQ ID NO:147), MGVKVLFALICIAVAEA (SEQ ID NO:148), METPAQLLFLLLLWLPDTT (SEQ ID NO:149); MKWVTFISLLFLFSSAYS (SEQ ID NO:150); or MDWTWRVFCLLAVTPGAH (SEQ ID NO:151). In one instance, the signal peptide consists of the sequence of SEQ ID NO: 170. Sequence-Optimized Nucleotide Sequences Encoding Fusion Proteins In some instances, the polynucleotide comprises a sequence-optimized nucleotide sequence encoding a fusion protein disclosed herein. In some cases, the polynucleotide of the disclosure comprises an open reading frame (ORF) encoding a fusion protein, wherein the ORF has been sequence optimized. In some cases, the sequence optimized sequence that encodes a fusion polypeptide described herein is used to practice the methods disclosed herein. In some instances, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding a fusion protein described herein, comprises from 5′ to 3′ end: (i) a 5′ cap such as provided herein, for example, m7Gp-ppGm, m7Gp-ppGm-A, or m7Gp-ppGm-G; (ii) a 5′ UTR comprising a nucleotide sequence, e.g., set forth in SEQ ID NO: 8 or 15; (iii) an open reading frame encoding a fusion protein of the disclosure, e.g., a sequence optimized nucleic acid sequence encoding the fusion protein; (iv) at least one stop codon (if not present at the 3’ end of ORF or at 5′ terminus of 3′UTR); Attorney Docket No.: 45817-0174WO1 (v) a 3′ UTR comprising a nucleotide sequence, e.g., set forth in SEQ ID NO:9 or SEQ ID NO:16 or 167; and (vi) a poly A tail (e.g., about 100 nt in length). In some cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding a fusion protein of the disclosure, comprises from 5′ to 3′ end: (i) a 5′ cap such as provided herein, for example, m7Gp-ppGm, m7Gp-ppGm-A, or m7Gp-ppGm-G; (ii) a 5′ UTR comprising the nucleotide sequence set forth in SEQ ID NO:15; (iii) an open reading frame encoding a fusion protein of the disclosure, e.g., a sequence optimized nucleic acid sequence encoding the fusion protein; (iv) at least one stop codon (if not present at the 3’ end of ORF or at 5′ terminus of 3′UTR); (v) a 3′ UTR comprising a nucleotide sequence set forth in SEQ ID NO:16 or 167; and (vi) a poly A tail (e.g., about 100 nt in length). In some cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding a fusion protein of the disclosure, comprises from 5′ to 3′ end: (i) a 5′ cap such as provided herein, for example, m7Gp-ppGm, m7Gp-ppGm-A, or m7Gp-ppGm-G; (ii) a 5′ UTR comprising the nucleotide sequence set forth in SEQ ID NO:8; (iii) an open reading frame encoding a fusion protein of the disclosure, e.g., a sequence optimized nucleic acid sequence encoding the fusion protein; (iv) at least one stop codon (if not present at the 3’ end of ORF or at 5′ terminus of 3′UTR); (v) a 3′ UTR comprising a nucleotide sequence set forth in SEQ ID NO:9 or 167; and (vi) a poly A tail (e.g., about 100 nt in length). Attorney Docket No.: 45817-0174WO1 In certain cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding a fusion protein of the disclosure, comprises from 5′ to 3′ end: (i) a 5′ cap comprising or consisting of m7Gp-ppGm; (ii) a 5′ UTR comprising the nucleotide sequence set forth in SEQ ID NO:15; (iii) an open reading frame encoding a fusion protein of SEQ ID NO:166 or 177, (optionally excluding the signal peptide encoded by SEQ ID NO:170 but instead including a different signal sequence); (iv) at least one stop codon (if not present at the 3’ end of ORF or at 5′ terminus of 3′UTR); (v) a 3′ UTR comprising a nucleotide sequence set forth in SEQ ID NO:16 or 167; and (vi) a poly A tail (e.g., about 100 nt in length). In other cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding a fusion protein of the disclosure, comprises from 5′ to 3′ end: (i) a 5′ cap comprising or consisting of m7Gp-ppGm; (ii) a 5′ UTR comprising the nucleotide sequence set forth in SEQ ID NO:15; (iii) an open reading frame comprising SEQ ID NO:165, (optionally excluding the signal peptide encoded by SEQ ID NO:170 but instead including a different signal sequence); (iv) at least one stop codon (if not present at the 3’ end of ORF or at 5′ terminus of 3′UTR); (v) a 3′ UTR comprising a nucleotide sequence set forth in SEQ ID NO:16 or 167; and (vi) a poly A tail (e.g., about 100 nt in length). In some cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding a fusion protein of the disclosure, comprises from 5′ to 3′ end: Attorney Docket No.: 45817-0174WO1 (i) a 5′ cap such as provided herein, for example, m7Gp-ppGm, m7Gp-ppGm-A, or m7Gp-ppGm-G; (ii) a 5′ UTR comprising the nucleotide sequence set forth in SEQ ID NO:15; (iii) an open reading frame encoding a fusion protein of the disclosure (e.g., SEQ ID NO:25, optionally excluding the signal peptide encoded by SEQ ID NO:25 but instead including a different signal sequence), e.g., a sequence optimized nucleic acid sequence encoding a fusion protein described herein (e.g., set forth as SEQ ID NO:3 optionally excluding the signal peptide in SEQ ID NO:3 but instead including a different signal sequence), e.g., a sequence optimized nucleic acid sequence encoding the fusion protein; (iv) at least one stop codon (if not present at the 3’ end of ORF or at 5′ terminus of 3′UTR); (v) a 3′ UTR comprising a nucleotide sequence set forth in SEQ ID NO:16 or 167; and (vi) a poly A tail (e.g., about 100 nt in length). In some cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding a fusion protein of the disclosure, comprises from 5′ to 3′ end: (i) a 5′ cap such as provided herein, for example, m7Gp-ppGm, m7Gp-ppGm-A, or m7Gp-ppGm-G; (ii) a 5′ UTR comprising the nucleotide sequence set forth in SEQ ID NO:8; (iii) an open reading frame encoding a fusion protein of the disclosure (e.g., SEQ ID NO:25, optionally excluding the signal peptide encoded by SEQ ID NO:25 but instead including a different signal sequence), e.g., a sequence optimized nucleic acid sequence encoding a fusion protein described herein (e.g., set forth as SEQ ID NO:3 optionally excluding the signal peptide in SEQ ID NO:3 but instead including a different signal sequence), e.g., a sequence optimized nucleic acid sequence encoding the fusion protein; (iv) at least one stop codon (if not present at the 3’ end of ORF or at 5′ terminus of 3′UTR); Attorney Docket No.: 45817-0174WO1 (v) a 3′ UTR comprising a nucleotide sequence set forth in SEQ ID NO:9 or 167; and (vi) a poly A tail (e.g., about 100 nt in length). In certain cases, all uracils in the polynucleotide are N1-methylpseudouracil. In some cases, all uracils in the polynucleotide are 5-methoxyuracil. The sequence-optimized nucleotide sequences disclosed herein are distinct from the corresponding wild type nucleotide acid sequences and from other known sequence- optimized nucleotide sequences, e.g., these sequence-optimized nucleic acids have unique compositional characteristics. In some cases, the percentage of uracil or thymine nucleobases in a sequence- optimized nucleotide sequence (e.g., encoding a fusion protein described herein) is modified (e.g., reduced) with respect to the percentage of uracil or thymine nucleobases in the reference wild-type nucleotide sequence. Such a sequence is referred to as a uracil- modified or thymine-modified sequence. The percentage of uracil or thymine content in a nucleotide sequence can be determined by dividing the number of uracils or thymines in a sequence by the total number of nucleotides and multiplying by 100. In some cases, the sequence-optimized nucleotide sequence has a lower uracil or thymine content than the uracil or thymine content in the reference wild-type sequence. In some cases, the uracil or thymine content in a sequence-optimized nucleotide sequence of the disclosure is greater than the uracil or thymine content in the reference wild-type sequence and still maintain beneficial effects, e.g., increased expression and / or reduced Toll-Like Receptor (TLR) response when compared to the reference wild-type sequence. Methods for optimizing codon usage are known in the art. For example, an ORF of any one or more of the sequences provided herein may be codon optimized. Codon optimization, in some cases, may be used to match codon frequencies in target and host organisms to ensure proper folding; bias GC content to increase mRNA stability or reduce secondary structures; minimize tandem repeat codons or base runs that may impair gene construction or expression; customize transcriptional and translational control regions; insert or remove protein trafficking sequences; remove / add post Attorney Docket No.: 45817-0174WO1 translation modification sites in encoded protein (e.g., glycosylation sites); add, remove or shuffle protein domains; insert or delete restriction sites; modify ribosome binding sites and mRNA degradation sites; adjust translational rates to allow the various domains of the protein to fold properly; or reduce or eliminate problem secondary structures within the polynucleotide. Codon optimization tools, algorithms and services are known in the art - non-limiting examples include services from GeneArt (Life Technologies), DNA2.0 (Menlo Park CA) and / or proprietary methods. In some cases, the open reading frame (ORF) sequence is optimized using optimization algorithms. Identification and Ratio Determination (IDR) Sequences An Identification and Ratio Determination (IDR) sequence is a sequence of a biological molecule (e.g., nucleic acid or protein) that, when combined with the sequence of a target biological molecule, serves to identify the target biological molecule. Typically, an IDR sequence is a heterologous sequence that is incorporated within or appended to a sequence of a target biological molecule and can be used as a reference to identify the target molecule. Thus, in some cases, a nucleic acid (e.g., mRNA) comprises (i) a target sequence of interest (e.g., a coding sequence encoding a therapeutic and / or antigenic peptide or protein); and (ii) a unique IDR sequence. An RNA species (e.g., RNA having a given coding sequence) may comprise an IDR sequence that differs from the IDR sequence of other RNA species (e.g., RNA(s) having different coding sequence(s)). Each IDR sequence thus identifies a particular RNA species, and so the abundance of IDR sequences may be measured to determine the abundance of each RNA species in a composition. Use of distinct IDR sequences to identify RNA species allows for analysis of multivalent RNA compositions (e.g., containing multiple RNA species) containing RNA species with similar coding sequences and / or lengths, which could otherwise be difficult to distinguish using PCR- or chromatography-based analysis of full-length RNAs. Each RNA species in a multivalent RNA composition may comprise an IDR sequence that is not a sequence isomer of an IDR sequence of another RNA species in a Attorney Docket No.: 45817-0174WO1 multivalent RNA composition (e.g., the IDR sequence does not have the same number of adenosine nucleotides, the same number of cytosine nucleotides, the same number of guanine nucleotides, and the same number of uracil nucleotides, as another IDR sequence in the composition, even if those sequences have different sequences). Having identical nucleotide compositions causes sequence isomers to have the same mass, presenting a challenge to distinguishing sequence isomers using mass-based identification methods (e.g., mass spectrometry). Each RNA species in a multivalent RNA composition may comprise an IDR sequence having a mass that differs from the mass of IDR sequences of each other RNA species in a multivalent RNA composition. For example, the mass of each IDR sequence may differ from the mass of other IDR sequences by at least 9 Da, at least 25 Da, at least 25 Da, or at least 50 Da. Use of IDR sequences with distinct masses allows RNA fragments comprising different IDR sequences to be distinguished using mass-based analysis methods (e.g., mass spectrometry), which do not require reverse transcription, amplification, or sequencing of RNAs. Each RNA species in an RNA composition may comprises an IDR sequence with a different length. For example, each IDR sequence may have a length independently selected from 0 to 25 nucleotides. The length of a nucleic acid influences the rate at which the nucleic acid traverses a chromatography column, and so the use of IDR sequences of different lengths on different RNA species allows RNA fragments having different IDR sequences to be distinguished using chromatography-based methods (e.g., LC-UV). IDR sequences may be chosen such that no IDR sequence comprises a start codon, ‘AUG’. Lack of a start codon in an IDR sequence prevents undesired translation of nucleotide sequences within and / or downstream from the IDR sequence. IDR sequences may be chosen such that no IDR sequence comprises a recognition site for a restriction enzyme. In one example, no IDR sequence comprises a recognition site for XbaI, ‘UCUAG’. Lack of a recognition site for a restriction enzyme (e.g., XbaI recognition site ‘UCUAG’) allows the restriction enzyme to be used in generating and Attorney Docket No.: 45817-0174WO1 modifying a DNA template for in vitro transcription, without affecting the IDR sequence or sequence of the transcribed RNA. In some cases, the IDR sequence may be inserted in a 3’UTR and / or a poly A tail. Modified Nucleotide Sequences Encoding Fusion Proteins In some instances, the polynucleotide (e.g., a RNA, e.g., an mRNA) comprises a chemically modified nucleobase, for example, a chemically modified uracil, e.g., pseudouracil, N1-methylpseudouracil, 5-methoxyuracil, or the like. In some cases, the mRNA is a uracil-modified sequence comprising an ORF encoding a fusion protein described herein, wherein the mRNA comprises a chemically modified nucleobase, for example, a chemically modified uracil, e.g., pseudouracil, N1-methylpseudouracil, or 5- methoxyuracil. In certain aspects of the disclosure, when the modified uracil base is connected to a ribose sugar, as it is in polynucleotides, the resulting modified nucleoside or nucleotide is referred to as modified uridine. In some cases, uracil in the polynucleotide is at least about 25%, at least about 30%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least 90%, at least 95%, at least 99%, or about 100% modified uracil. In one case, uracil in the polynucleotide is at least 95% modified uracil. In another case, uracil in the polynucleotide is 100% modified uracil. In instances where uracil in the polynucleotide is at least 95% modified uracil overall uracil content can be adjusted such that an mRNA provides suitable protein expression levels while inducing little to no immune response. In some cases, the uracil content of the ORF is between about 100% and about 150%, between about 100% and about 110%, between about 105% and about 115%, between about 110% and about 120%, between about 115% and about 125%, between about 120% and about 130%, between about 125% and about 135%, between about 130% and about 140%, between about 135% and about 145%, between about 140% and about 150% of the theoretical minimum uracil content in the corresponding wild-type ORF (%UTM). In other cases, the uracil content of the ORF is between about 121% and about 136% or between 123% and Attorney Docket No.: 45817-0174WO1 134% of the %UTM. In some cases, the uracil content of the ORF encoding a fusion protein described herein is about 115%, about 120%, about 125%, about 130%, about 135%, about 140%, about 145%, or about 150% of the %UTM. In this context, the term "uracil" can refer to modified uracil and / or naturally occurring uracil. In some instances, the uracil content in the ORF of the mRNA encoding a fusion protein of the disclosure is less than about 30%, about 25%, about 20%, about 15%, or about 10% of the total nucleobase content in the ORF. In some cases, the uracil content in the ORF is between about 10% and about 20% of the total nucleobase content in the ORF. In other cases, the uracil content in the ORF is between about 10% and about 25% of the total nucleobase content in the ORF. In one case, the uracil content in the ORF of the mRNA encoding a fusion protein described herein is less than about 20% of the total nucleobase content in the open reading frame. In this context, the term "uracil" can refer to modified uracil and / or naturally occurring uracil. In further instances, the ORF of the mRNA encoding a fusion protein having modified uracil and adjusted uracil content has increased Cytosine (C), Guanine (G), or Guanine / Cytosine (G / C) content (absolute or relative). In some cases, the overall increase in C, G, or G / C content (absolute or relative) of the ORF is at least about 2%, at least about 3%, at least about 4%, at least about 5%, at least about 6%, at least about 7%, at least about 10%, at least about 15%, at least about 20%, at least about 40%, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, or at least about 100% relative to the G / C content (absolute or relative) of the wild-type ORF. In some cases, the G, the C, or the G / C content in the ORF is less than about 100%, less than about 90%, less than about 85%, or less than about 80% of the theoretical maximum G, C, or G / C content of the corresponding wild type nucleotide sequence encoding the fusion protein (%GTMX; %CTMX, or %G / CTMX). In some cases, the increases in G and / or C content (absolute or relative) described herein can be conducted by replacing synonymous codons with low G, C, or G / C content with synonymous codons having higher G, C, or G / C content. In other cases, the increase in G Attorney Docket No.: 45817-0174WO1 and / or C content (absolute or relative) is conducted by replacing a codon ending with U with a synonymous codon ending with G or C. In further instances, the ORF of the mRNA encoding a fusion protein of the disclosure comprises modified uracil and has an adjusted uracil content containing less uracil pairs (UU) and / or uracil triplets (UUU) and / or uracil quadruplets (UUUU) than the corresponding wild-type nucleotide sequence encoding the fusion protein. In some cases, the ORF of the mRNA encoding a fusion protein of the disclosure contains no uracil pairs and / or uracil triplets and / or uracil quadruplets. In some cases, uracil pairs and / or uracil triplets and / or uracil quadruplets are reduced below a certain threshold, e.g., no more than 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 occurrences in the ORF of the mRNA encoding the fusion protein. In a particular instance, the ORF of the mRNA encoding the fusion protein of the disclosure contains less than 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 non-phenylalanine uracil pairs and / or triplets. In another case, the ORF of the mRNA encoding a fusion protein of the disclosure contains no non-phenylalanine uracil pairs and / or triplets. In further instances, the ORF of the mRNA encoding a fusion protein of the disclosure comprises modified uracil and has an adjusted uracil content containing less uracil-rich clusters than the corresponding wild-type nucleotide sequence encoding the fusion protein. In some instances, the ORF of the mRNA encoding the fusion protein of the disclosure contains uracil-rich clusters that are shorter in length than corresponding uracil-rich clusters in the corresponding wild-type nucleotide sequence encoding the fusion protein. In further instances, alternative lower frequency codons are employed. At least about 5%, at least about 10%, at least about 15%, at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, at least about 60%, at least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 95%, at least about 99%, or 100% of the codons in the fusion protein-encoding ORF of the modified uracil-comprising mRNA are substituted with alternative codons, Attorney Docket No.: 45817-0174WO1 each alternative codon having a codon frequency lower than the codon frequency of the substituted codon in the synonymous codon set. The ORF also has adjusted uracil content, as described above. In some cases, at least one codon in the ORF of the mRNA encoding the fusion protein is substituted with an alternative codon having a codon frequency lower than the codon frequency of the substituted codon in the synonymous codon set. In some cases, the adjusted uracil content, fusion protein-encoding ORF of the modified uracil-comprising mRNA exhibits expression levels of fusion protein when administered to a mammalian cell that are higher than expression levels of the fusion protein from the corresponding wild-type mRNA. In some cases, the mammalian cell is a mouse cell, a rat cell, or a rabbit cell. In other cases, the mammalian cell is a monkey cell or a human cell. In some cases, the human cell is a HeLa cell, a BJ fibroblast cell, or a peripheral blood mononuclear cell (PBMC). In some cases, the fusion protein is expressed at a level higher than expression levels of the fusion protein from the corresponding wild-type mRNA when the mRNA is administered to a mammalian cell in vivo. In some cases, the mRNA is administered to mice, rabbits, rats, monkeys, or humans. In one case, mice are null mice. In some cases, the mRNA is administered intravenously, subcutaneously, or intramuscularly. In other cases, the fusion protein is expressed when the mRNA is administered to a mammalian cell in vitro. In some cases, the expression is increased by at least about 2-fold, at least about 5-fold, at least about 10- fold, at least about 50-fold, at least about 500-fold, at least about 1500-fold, or at least about 3000-fold. In other cases, the expression is increased by at least about 10%, about 20%, about 30%, about 40%, about 50%, 60%, about 70%, about 80%, about 90%, or about 100%. In some instances, adjusted uracil content, fusion protein-encoding ORF of the modified uracil-comprising mRNA exhibits increased stability. In some cases, the mRNA exhibits increased stability in a cell relative to the stability of a corresponding wild-type mRNA under the same conditions. In some cases, the mRNA exhibits increased stability including resistance to nucleases, thermal stability, and / or increased Attorney Docket No.: 45817-0174WO1 stabilization of secondary structure. In some cases, increased stability exhibited by the mRNA is measured by determining the half-life of the mRNA (e.g., in a plasma, serum, cell, or tissue sample) and / or determining the area under the curve (AUC) of the protein expression by the mRNA over time (e.g., in vitro or in vivo). An mRNA is identified as having increased stability if the half-life and / or the AUC is greater than the half-life and / or the AUC of a corresponding wild-type mRNA under the same conditions. In some cases, the mRNA of the present disclosure induces a detectably lower immune response (e.g., innate or acquired) relative to the immune response induced by a corresponding wild-type mRNA under the same conditions. In other cases, the mRNA of the present disclosure induces a detectably lower immune response (e.g., innate or acquired) relative to the immune response induced by an mRNA that encodes for a fusion protein but does not comprise modified uracil under the same conditions, or relative to the immune response induced by an mRNA that encodes for a fusion protein and that comprises modified uracil but that does not have adjusted uracil content under the same conditions. The innate immune response can be manifested by increased expression of pro-inflammatory cytokines, activation of intracellular PRRs (RIG-I, MDA5, etc.), cell death, and / or termination or reduction in protein translation. In some cases, a reduction in the innate immune response can be measured by expression or activity level of Type 1 interferons (e.g., IFN-α, IFN-β, IFN-κ, IFN-δ, IFN-ε, IFN-τ, IFN-ω, and IFN-ζ) or the expression of interferon-regulated genes such as the toll-like receptors (e.g., TLR7 and TLR8), and / or by decreased cell death following one or more administrations of the mRNA of the disclosure into a cell as compared to unmodified mRNA. In some cases, the expression of Type-1 interferons by a mammalian cell in response to the mRNA of the present disclosure is reduced by at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 99%, 99.9%, or greater than 99.9% relative to a corresponding wild-type mRNA, to an mRNA that encodes a fusion protein of the disclosure but does not comprise modified uracil, or to an mRNA that encodes a fusion protein and that comprises modified uracil but that does not have adjusted uracil content. In cases, the interferon is IFN-β. In some cases, cell death frequency caused by Attorney Docket No.: 45817-0174WO1 administration of mRNA of the present disclosure to a mammalian cell is 10%, 25%, 50%, 75%, 85%, 90%, 95%, or over 95% less than the cell death frequency observed with a corresponding wild-type mRNA, an mRNA that encodes for a fusion protein but does not comprise modified uracil, or mRNA that encodes for a fusion protein and that comprises modified uracil but that does not have adjusted uracil content. In some cases, the mammalian cell is a BJ fibroblast cell. In other cases, the mammalian cell is a splenocyte. In some cases, the mammalian cell is that of a mouse or a rat. In other cases, the mammalian cell is that of a human. In one case, the mRNA of the present disclosure does not substantially induce an innate immune response of a mammalian cell into which the mRNA is introduced. Methods for Modifying Polynucleotides The disclosure includes modified polynucleotides comprising a polynucleotide described herein (e.g., a polynucleotide, e.g. mRNA, comprising a nucleotide sequence encoding a fusion protein described herein. The modified polynucleotides can be chemically modified and / or structurally modified. When the polynucleotides are chemically and / or structurally modified the polynucleotides can be referred to as "modified polynucleotides." The present disclosure provides for modified nucleosides and nucleotides of a polynucleotide (e.g., RNA polynucleotides, such as mRNA polynucleotides) encoding a fusion protein of the disclosure. A "nucleoside" refers to a compound containing a sugar molecule (e.g., a pentose or ribose) or a derivative thereof in combination with an organic base (e.g., a purine or pyrimidine) or a derivative thereof (also referred to herein as "nucleobase"). A “nucleotide" refers to a nucleoside including a phosphate group. Modified nucleotides can be synthesized by any useful method, such as, for example, chemically, enzymatically, or recombinantly, to include one or more modified or non- natural nucleosides. Polynucleotides can comprise a region or regions of linked nucleosides. Such regions can have variable backbone linkages. The linkages can be Attorney Docket No.: 45817-0174WO1 standard phosphodiester linkages, in which case the polynucleotides would comprise regions of nucleotides. The modified polynucleotides disclosed herein can comprise various distinct modifications. In some instances, the modified polynucleotides contain one, two, or more (optionally different) nucleoside or nucleotide modifications. In some instances, a modified polynucleotide, introduced to a cell can exhibit one or more desirable properties, e.g., improved protein expression, reduced immunogenicity, or reduced degradation in the cell, as compared to an unmodified polynucleotide. In some instances, a polynucleotide of the present disclosure (e.g., a polynucleotide comprising a nucleotide sequence encoding a fusion protein of the disclosure is structurally modified. As used herein, a "structural" modification is one in which two or more linked nucleosides are inserted, deleted, duplicated, inverted or randomized in a polynucleotide without significant chemical modification to the nucleotides themselves. Because chemical bonds will necessarily be broken and reformed to effect a structural modification, structural modifications are of a chemical nature and hence are chemical modifications. However, structural modifications will result in a different sequence of nucleotides. For example, the polynucleotide "ATCG" can be chemically modified to "AT-5meC-G". The same polynucleotide can be structurally modified from "ATCG" to "ATCCCG". Here, the dinucleotide "CC" has been inserted, resulting in a structural modification to the polynucleotide. Therapeutic compositions of the present disclosure comprise, in some cases, at least one nucleic acid (e.g., RNA) having an open reading frame encoding a fusion protein of the disclosure, wherein the nucleic acid comprises nucleotides and / or nucleosides that can be standard (unmodified) or modified as is known in the art. In some instances, nucleotides and nucleosides of the present disclosure comprise modified nucleotides or nucleosides. Such modified nucleotides and nucleosides can be naturally- occurring modified nucleotides and nucleosides or non-naturally occurring modified nucleotides and nucleosides. Such modifications can include those at the sugar, Attorney Docket No.: 45817-0174WO1 backbone, or nucleobase portion of the nucleotide and / or nucleoside as are recognized in the art. In some instances, a naturally-occurring modified nucleotide or nucleotide of the disclosure is one as is generally known or recognized in the art. Non-limiting examples of such naturally occurring modified nucleotides and nucleotides can be found, inter alia, in the widely recognized MODOMICS database. In some instances, a non-naturally occurring modified nucleotide or nucleoside of the disclosure is one as is generally known or recognized in the art. Non-limiting examples of such non-naturally occurring modified nucleotides and nucleosides can be found, inter alia, in published US application Nos. PCT / US2012 / 058519; PCT / US2013 / 075177; PCT / US2014 / 058897; PCT / US2014 / 058891; PCT / US2014 / 070413; PCT / US2015 / 36773; PCT / US2015 / 36759; PCT / US2015 / 36771; or PCT / IB2017 / 051367 all of which are incorporated by reference herein. In some cases, a modified RNA nucleic acid (e.g., a modified mRNA nucleic acid), introduced to a cell or organism, exhibits reduced degradation in the cell or organism, respectively, relative to an unmodified nucleic acid comprising standard nucleotides and nucleosides. In some cases, a modified RNA nucleic acid (e.g., a modified mRNA nucleic acid), introduced into a cell or organism, may exhibit reduced immunogenicity in the cell or organism, respectively (e.g., a reduced innate response) relative to an unmodified nucleic acid comprising standard nucleotides and nucleosides. Nucleic acids (e.g., RNA nucleic acids, such as mRNA nucleic acids), in some cases, comprise non-natural modified nucleotides that are introduced during synthesis or post-synthesis of the nucleic acids to achieve desired functions or properties. The modifications may be present on internucleotide linkages, purine or pyrimidine bases, or sugars. The modification may be introduced with chemical synthesis or with a polymerase enzyme at the terminal of a chain or anywhere else in the chain. Any of the regions of a nucleic acid may be chemically modified. Attorney Docket No.: 45817-0174WO1 The present disclosure provides for modified nucleosides and nucleotides of a nucleic acid (e.g., RNA nucleic acids, such as mRNA nucleic acids). A “nucleoside” refers to a compound containing a sugar molecule (e.g., a pentose or ribose) or a derivative thereof in combination with an organic base (e.g., a purine or pyrimidine) or a derivative thereof (also referred to herein as “nucleobase”). A “nucleotide” refers to a nucleoside, including a phosphate group. Modified nucleotides may by synthesized by any useful method, such as, for example, chemically, enzymatically, or recombinantly, to include one or more modified or non-natural nucleosides. Nucleic acids can comprise a region or regions of linked nucleosides. Such regions may have variable backbone linkages. The linkages can be standard phosphodiester linkages, in which case the nucleic acids would comprise regions of nucleotides. Modified nucleotide base pairing encompasses not only the standard adenosine- thymine, adenosine-uracil, or guanosine-cytosine base pairs, but also base pairs formed between nucleotides and / or modified nucleotides comprising non-standard or modified bases, wherein the arrangement of hydrogen bond donors and hydrogen bond acceptors permits hydrogen bonding between a non-standard base and a standard base or between two complementary non-standard base structures, such as, for example, in those nucleic acids having at least one chemical modification. One example of such non-standard base pairing is the base pairing between the modified nucleotide inosine and adenine, cytosine or uracil. Any combination of base / sugar or linker may be incorporated into nucleic acids of the present disclosure. In some instances, modified nucleobases in nucleic acids (e.g., RNA nucleic acids, such as mRNA nucleic acids) comprise N1-methyl-pseudouridine (m1ψ), 1-ethyl- pseudouridine (e1ψ), 5-methoxy-uridine (mo5U), 5-methyl-cytidine (m5C), and / or pseudouridine (ψ). In some instances, modified nucleobases in nucleic acids (e.g., RNA nucleic acids, such as mRNA nucleic acids) comprise 5-methoxymethyl uridine, 5- methylthio uridine, 1-methoxymethyl pseudouridine, 5-methyl cytidine, and / or 5- methoxy cytidine. In some instances, the polyribonucleotide includes a combination of at Attorney Docket No.: 45817-0174WO1 least two (e.g., 2, 3, 4 or more) of any of the aforementioned modified nucleobases, including but not limited to chemical modifications. In some cases, a RNA nucleic acid of the disclosure comprises N1-methyl- pseudouridine (m1ψ) substitutions at one or more or all uridine positions of the nucleic acid. In one cases, a RNA nucleic acid of the disclosure comprises N1-methyl- pseudouridine (m1ψ) substitutions at all uridine positions of the nucleic acid. In a preferred embodiment, such nucleobases are incorporated during an IVT reaction. In some instances, a RNA nucleic acid of the disclosure comprises N1-methyl- pseudouridine (m1ψ) substitutions at one or more or all uridine positions of the nucleic acid and 5-methyl cytidine substitutions at one or more or all cytidine positions of the nucleic acid. In some cases, a RNA nucleic acid of the disclosure comprises pseudouridine (ψ) substitutions at one or more or all uridine positions of the nucleic acid. In some cases, a RNA nucleic acid of the disclosure comprises pseudouridine (ψ) substitutions at one or more or all uridine positions of the nucleic acid and 5-methyl cytidine substitutions at one or more or all cytidine positions of the nucleic acid. In some cases, a RNA nucleic acid of the disclosure comprises uridine at one or more or all uridine positions of the nucleic acid. In some instances, nucleic acids (e.g., RNA nucleic acids, such as mRNA nucleic acids) are uniformly modified (e.g., fully modified, modified throughout the entire sequence) for a particular modification. For example, a nucleic acid can be uniformly modified with N1-methyl-pseudouridine, meaning that all uridine residues in the mRNA sequence are replaced with N1-methyl-pseudouridine. Similarly, a nucleic acid can be uniformly modified for any type of nucleoside residue present in the sequence by replacement with a modified residue such as those set forth above. The nucleic acids of the present disclosure may be partially or fully modified along the entire length of the molecule. For example, one or more or all or a given type of nucleotide (e.g., purine or pyrimidine, or any one or more or all of A, G, U, C) may be Attorney Docket No.: 45817-0174WO1 uniformly modified in a nucleic acid of the disclosure, or in a predetermined sequence region thereof (e.g., in the mRNA including or excluding the poly A tail). In some instances, all nucleotides X in a nucleic acid of the present disclosure (or in a sequence region thereof) are modified nucleotides, wherein X may be any one of nucleotides A, G, U, C, or any one of the combinations A+G, A+U, A+C, G+U, G+C, U+C, A+G+U, A+G+C, G+U+C or A+G+C. The nucleic acid may contain from about 1% to about 100% modified nucleotides (either in relation to overall nucleotide content, or in relation to one or more types of nucleotide, i.e., any one or more of A, G, U or C) or any intervening percentage (e.g., from 1% to 20%, from 1% to 25%, from 1% to 50%, from 1% to 60%, from 1% to 70%, from 1% to 80%, from 1% to 90%, from 1% to 95%, from 10% to 20%, from 10% to 25%, from 10% to 50%, from 10% to 60%, from 10% to 70%, from 10% to 80%, from 10% to 90%, from 10% to 95%, from 10% to 100%, from 20% to 25%, from 20% to 50%, from 20% to 60%, from 20% to 70%, from 20% to 80%, from 20% to 90%, from 20% to 95%, from 20% to 100%, from 50% to 60%, from 50% to 70%, from 50% to 80%, from 50% to 90%, from 50% to 95%, from 50% to 100%, from 70% to 80%, from 70% to 90%, from 70% to 95%, from 70% to 100%, from 80% to 90%, from 80% to 95%, from 80% to 100%, from 90% to 95%, from 90% to 100%, and from 95% to 100%). It will be understood that any remaining percentage is accounted for by the presence of unmodified A, G, U, or C. The nucleic acids may contain at a minimum 1% and at maximum 100% modified nucleotides, or any intervening percentage, such as at least 5% modified nucleotides, at least 10% modified nucleotides, at least 25% modified nucleotides, at least 50% modified nucleotides, at least 80% modified nucleotides, or at least 90% modified nucleotides. For example, the nucleic acids may contain a modified pyrimidine such as a modified uracil or cytosine. In some instances, at least 5%, at least 10%, at least 25%, at least 50%, at least 80%, at least 90% or 100% of the uracil in the nucleic acid is replaced with a modified uracil (e.g., a 5-substituted uracil). The modified uracil can be replaced by a compound having a single unique structure, or can be replaced by a plurality of Attorney Docket No.: 45817-0174WO1 compounds having different structures (e.g., 2, 3, 4 or more unique structures). In some instances, at least 5%, at least 10%, at least 25%, at least 50%, at least 80%, at least 90% or 100% of the cytosine in the nucleic acid is replaced with a modified cytosine (e.g., a 5- substituted cytosine). The modified cytosine can be replaced by a compound having a single unique structure, or can be replaced by a plurality of compounds having different structures (e.g., 2, 3, 4 or more unique structures). Untranslated Regions (UTRs) Untranslated regions (UTRs) are nucleic acid sections of a polynucleotide before a start codon (5′ UTR) and after a stop codon (3′ UTR) that are not translated. In some instances, a polynucleotide (e.g., a ribonucleic acid (RNA), e.g., a messenger RNA (mRNA)) of the disclosure comprising an open reading frame (ORF) encoding a fusion protein described herein further comprises UTRs (e.g., a 5′ UTR or functional fragment thereof, a 3′ UTR or functional fragment thereof, or a combination thereof). A UTR (e.g., 5′ UTR or 3′ UTR) can be homologous or heterologous to the coding region in a polynucleotide. In some instances, the UTR is homologous to the ORF encoding the antigen. In some instances, the UTR is heterologous to the ORF encoding the antigen. In some instances, the polynucleotide comprises two or more 5′ UTRs or functional fragments thereof, each of which has the same or different nucleotide sequences. In some instances, the polynucleotide comprises two or more 3′ UTRs or functional fragments thereof, each of which has the same or different nucleotide sequences. In some instances, the 5′ UTR or functional fragment thereof, 3′ UTR or functional fragment thereof, or any combination thereof is sequence optimized. In some instances, the 5′UTR or functional fragment thereof, 3′ UTR or functional fragment thereof, or any combination thereof comprises at least one chemically modified nucleobase, e.g., N1-methylpseudouracil or 5-methoxyuracil. Attorney Docket No.: 45817-0174WO1 UTRs can have features that provide a regulatory role, e.g., increased or decreased stability, localization and / or translation efficiency. A polynucleotide comprising a UTR can be administered to a cell, tissue, or organism, and one or more regulatory features can be measured using routine methods. In some instances, a functional fragment of a 5′ UTR or 3′ UTR comprises one or more regulatory features of a full length 5′ or 3′ UTR, respectively. Natural 5′UTRs bear features that play roles in translation initiation. They harbor signatures like Kozak sequences that are commonly known to be involved in the process by which the ribosome initiates translation of many genes. Kozak sequences have the consensus CCR(A / G)CCAUGG, where R is a purine (adenine or guanine) three bases upstream of the start codon (AUG), which is followed by another ‘G’.5′ UTRs also have been known to form secondary structures that are involved in elongation factor binding. By engineering the features typically found in abundantly expressed genes of specific target organs, one can enhance the stability and protein production of a polynucleotide. For example, introduction of 5′ UTR of liver-expressed mRNA, such as albumin, serum amyloid A, Apolipoprotein A / B / E, transferrin, alpha fetoprotein, erythropoietin, or Factor VIII, can enhance expression of polynucleotides in hepatic cell lines or liver. Likewise, use of 5′UTR from other tissue-specific mRNA to improve expression in that tissue is possible for muscle (e.g., MyoD, Myosin, Myoglobin, Myogenin, Herculin), for endothelial cells (e.g., Tie-1, CD36), for myeloid cells (e.g., C / EBP, AML1, G-CSF, GM-CSF, CD11b, MSR, Fr-1, i-NOS), for leukocytes (e.g., CD45, CD18), for adipose tissue (e.g., CD36, GLUT4, ACRP30, adiponectin) and for lung epithelial cells (e.g., SP- A / B / C / D). In some instances, UTRs are selected from a family of transcripts whose proteins share a common function, structure, feature or property. For example, an encoded polypeptide can belong to a family of proteins (i.e., that share at least one function, structure, feature, localization, origin, or expression pattern), which are expressed in a particular cell, tissue or at some time during development. The UTRs from any of the Attorney Docket No.: 45817-0174WO1 genes or mRNA can be swapped for any other UTR of the same or different family of proteins to create a new polynucleotide. In some instances, the 5′ UTR and the 3′ UTR can be heterologous. In some instances, the 5′ UTR can be derived from a different species than the 3′ UTR. In some instances, the 3′ UTR can be derived from a different species than the 5′ UTR. Co-owned International Patent Application No. PCT / US2014 / 021522 (Publ. No. WO 2014 / 164253, incorporated herein by reference in its entirety) provides a listing of exemplary UTRs that can be utilized in the polynucleotide of the present disclosure as flanking regions to an ORF. Additional exemplary UTRs of the application include, but are not limited to, one or more 5′UTR and / or 3′UTR derived from the nucleic acid sequence of: a globin, such as an α- or β-globin (e.g., a Xenopus, mouse, rabbit, or human globin); a strong Kozak translational initiation signal; a CYBA (e.g., human cytochrome b-245 α polypeptide); an albumin (e.g., human albumin7); a HSD17B4 (hydroxysteroid (17-β) dehydrogenase); a virus (e.g., a tobacco etch virus (TEV), a Venezuelan equine encephalitis virus (VEEV), a Dengue virus, a cytomegalovirus (CMV) (e.g., CMV immediate early 1 (IE1)), a hepatitis virus (e.g., hepatitis B virus), a sindbis virus, or a PAV barley yellow dwarf virus); a heat shock protein (e.g., hsp70); a translation initiation factor (e.g., elF4G); a glucose transporter (e.g., hGLUT1 (human glucose transporter 1)); an actin (e.g., human α or β actin); a GAPDH; a tubulin; a histone; a citric acid cycle enzyme; a topoisomerase (e.g., a 5′UTR of a TOP gene lacking the 5′ TOP motif (the oligopyrimidine tract)); a ribosomal protein Large 32 (L32); a ribosomal protein (e.g., human or mouse ribosomal protein, such as, for example, rps9); an ATP synthase (e.g., ATP5A1 or the β subunit of mitochondrial H+-ATP synthase); a growth hormone e (e.g., bovine (bGH) or human (hGH)); an elongation factor (e.g., elongation factor 1 α1 (EEF1A1)); a manganese superoxide dismutase (MnSOD); a myocyte enhancer factor 2A (MEF2A); a β-F1- ATPase, a creatine kinase, a myoglobin, a granulocyte-colony stimulating factor (G- CSF); a collagen (e.g., collagen type I, alpha 2 (Col1A2), collagen type I, alpha 1 (Col1A1), collagen type VI, alpha 2 (Col6A2), collagen type VI, alpha 1 (Col6A1)); a Attorney Docket No.: 45817-0174WO1 ribophorin (e.g., ribophorin I (RPNI)); a low density lipoprotein receptor-related protein (e.g., LRP1); a cardiotrophin-like cytokine factor (e.g., Nnt1); calreticulin (Calr); a procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1 (Plod1); and a nucleobindin (e.g., Nucb1). In some instances, the 5′ UTR is selected from the group consisting of a β-globin 5′ UTR; a 5′UTR containing a strong Kozak translational initiation signal; a cytochrome b-245 α polypeptide (CYBA) 5′ UTR; a hydroxysteroid (17-β) dehydrogenase (HSD17B4) 5′ UTR; a Tobacco etch virus (TEV) 5′ UTR; a Venezuelan equine encephalitis virus (VEEV) 5′ UTR; a 5′ proximal open reading frame of rubella virus (RV) RNA encoding nonstructural proteins; a Dengue virus (DEN) 5′ UTR; a heat shock protein 70 (Hsp70) 5′ UTR; a eIF4G 5′ UTR; a GLUT15′ UTR; functional fragments thereof and any combination thereof. In some instances, the 3′ UTR is selected from the group consisting of a β-globin 3′ UTR; a CYBA 3′ UTR; an albumin 3′ UTR; a growth hormone (GH) 3′ UTR; a VEEV 3′ UTR; a hepatitis B virus (HBV) 3′ UTR; α-globin 3′UTR; a DEN 3′ UTR; a PAV barley yellow dwarf virus (BYDV-PAV) 3′ UTR; an elongation factor 1 α1 (EEF1A1) 3′ UTR; a manganese superoxide dismutase (MnSOD) 3′ UTR; a β subunit of mitochondrial H(+)-ATP synthase (β-mRNA) 3′ UTR; a GLUT13′ UTR; a MEF2A 3′ UTR; a β-F1- ATPase 3′ UTR; functional fragments thereof and combinations thereof. Wild-type UTRs derived from any gene or mRNA can be incorporated into the polynucleotides of the disclosure. In some cases, a UTR can be altered relative to a wild type or native UTR to produce a variant UTR, e.g., by changing the orientation or location of the UTR relative to the ORF; or by inclusion of additional nucleotides, deletion of nucleotides, swapping or transposition of nucleotides. In some cases, variants of 5′ or 3′ UTRs can be utilized, for example, mutants of wild type UTRs, or variants wherein one or more nucleotides are added to or removed from a terminus of the UTR. Additionally, one or more synthetic UTRs can be used in combination with one or more non-synthetic UTRs. See, e.g., Mandal and Rossi, Nat. Protoc.20138(3):568-82, the contents of which are incorporated herein by reference in their entirety. Attorney Docket No.: 45817-0174WO1 UTRs or portions thereof can be placed in the same orientation as in the transcript from which they were selected or can be altered in orientation or location. Hence, a 5′ and / or 3′ UTR can be inverted, shortened, lengthened, or combined with one or more other 5′ UTRs or 3′ UTRs. In some cases, the polynucleotide comprises multiple UTRs, e.g., a double, a triple or a quadruple 5′ UTR or 3′ UTR. For example, a double UTR comprises two copies of the same UTR either in series or substantially in series. For example, a double beta-globin 3′UTR can be used (see US2010 / 0129877, the contents of which are incorporated herein by reference in its entirety). The polynucleotides of the disclosure can comprise combinations of features. For example, the ORF can be flanked by a 5′UTR that comprises a strong Kozak translational initiation signal and / or a 3′UTR comprising an oligo(dT) sequence for templated addition of a poly A tail. A 5′UTR can comprise a first polynucleotide fragment and a second polynucleotide fragment from the same and / or different UTRs (see, e.g., US2010 / 0293625, herein incorporated by reference in its entirety). Other non-UTR sequences can be used as regions or subregions within the polynucleotides of the disclosure. For example, introns or portions of intron sequences can be incorporated into the polynucleotides of the disclosure. Incorporation of intronic sequences can increase protein production as well as polynucleotide expression levels. In some instances, the 3’UTR includes an IDR sequence(s). In some cases, the polynucleotide of the disclosure comprises an internal ribosome entry site (IRES) instead of or in addition to a UTR (see, e.g., Yakubov et al., Biochem. Biophys. Res. Commun. 2010394(1):189-193, the contents of which are incorporated herein by reference in their entirety). In some cases, the polynucleotide comprises an IRES instead of a 5′ UTR sequence. In some cases, the polynucleotide comprises an ORF and a viral capsid sequence. In some cases, the polynucleotide comprises a synthetic 5′ UTR in combination with a non-synthetic 3′ UTR. In some cases, the UTR can also include at least one translation enhancer polynucleotide, translation enhancer element, or translational enhancer elements Attorney Docket No.: 45817-0174WO1 (collectively, "TEE," which refers to nucleic acid sequences that increase the amount of polypeptide or protein produced from a polynucleotide. As a non-limiting example, the TEE can be located between the transcription promoter and the start codon. In some cases, the 5′ UTR comprises a TEE. In one case, a TEE is a conserved element in a UTR that can promote translational activity of a nucleic acid such as, but not limited to, cap-dependent or cap-independent translation. 5′ UTR sequences 5′ UTR sequences are important for ribosome recruitment to the mRNA and have been reported to play a role in translation (Hinnebusch A, et al., (2016) Science, 352:6292: 1413-6). Disclosed herein, inter alia, is a polynucleotide, e.g., mRNA, comprising an open reading frame encoding a fusion protein described herein, which polynucleotide has a 5′ UTR that confers an increased half-life, increased expression and / or increased activity of the polypeptide encoded by said polynucleotide, or of the polynucleotide itself. In an instance, a polynucleotide disclosed herein comprises: (a) a 5′-UTR (e.g., as provided in Table 3 or a variant or fragment thereof); (b) a coding region comprising a stop element (e.g., as described herein); and (c) a 3′-UTR (e.g., as described herein), and LNP compositions comprising the same. In one instance, the polynucleotide comprises a 5′- UTR comprising a sequence provided in Table 3 or a variant or fragment thereof (e.g., a functional variant or fragment thereof). In one instance, the polynucleotide comprises a 5′-UTR comprising the sequence of SEQ ID NO:50. In one instance, the polynucleotide having a 5′ UTR sequence provided in Table 3 or a variant or fragment thereof, has an increase in the half-life of the polynucleotide, e.g., about 1.5-20-fold increase in half-life of the polynucleotide. In an instance, the increase in half-life is about 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20- fold, or more. In an instance, the increase in half-life is about 1.5-fold or more. In an instance, the increase in half-life is about 2-fold or more. In an instance, the increase in Attorney Docket No.: 45817-0174WO1 half-life is about 3-fold or more. In an instance, the increase in half-life is about 4-fold or more. In an instance, the increase in half -life is about 5-fold or more. In one instance, the polynucleotide having a 5′ UTR sequence provided in Table 3 or a variant or fragment thereof, results in an increased level and / or activity, e.g., output, of the polypeptide encoded by the polynucleotide. In an instance, the 5′UTR results in about 1.5-20-fold increase in level and / or activity, e.g., output, of the polypeptide encoded by the polynucleotide. In an instance, the increase in level and / or activity is about 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20-fold, or more. In one case, the increase in level and / or activity is about 1.5-fold or more. In one case, the increase in level and / or activity is about 2-fold or more. In another case, the increase in level and / or activity is about 3-fold or more. In another case, the increase in level and / or activity is about 4-fold or more. In one case, the increase in level and / or activity is about 5-fold or more. In one instance, the increase is compared to an otherwise similar polynucleotide which does not have a 5′ UTR, has a different 5′ UTR, or does not have a 5′ UTR described in Table 3 or a variant or fragment thereof. In one instance, the increase in half-life of the polynucleotide is measured according to an assay that measures the half-life of a polynucleotide. In one instance, the increase in level and / or activity, e.g., output, of the polypeptide encoded by the polynucleotide is measured according to an assay that measures the level and / or activity of a polypeptide. In one instance, the 5′ UTR comprises a sequence provided in Table 3 or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to a 5′ UTR sequence provided in Table 3, or a variant or a fragment thereof. In certain cases, the 5′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 50, SEQ ID NO: 51, SEQ ID NO: 52, SEQ ID NO: 53, SEQ ID NO: 54, SEQ ID NO: 55, SEQ ID NO: 56, SEQ ID NO: 57, or SEQ ID NO: 58. Attorney Docket No.: 45817-0174WO1 In one instance, the 5′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 50. In another instance, the 5′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 15. In another instance, the 5′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 51. In yet another instance, the 5′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 52. In a further instance, the 5′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 53. In another instance, the 5′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 54. In another instance, the 5′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 55. In another instance, the 5′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 56. In another instance, the 5′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 57. In another instance, the 5′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 58. In another instance, the 5′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO:8. In some cases, the 5′ UTR comprises the sequence of SEQ ID NO:50. In some cases, the 5′ UTR comprises the sequence of SEQ ID NO:59 with an added A or G nucleotide at the N-terminus. In one instance, the 5′ UTR comprises or consists of the sequence of SEQ ID NO:15. In one instance, the 5′ UTR comprises or consists of the sequence of SEQ ID NO:8. In some instances, a 5′ UTR sequence provided in Table 3 has a first nucleotide which is an A. For example, the 5’UTR of SEQ ID NO:50 with an A as the first nucleotide is the 5’UTR provided in SEQ ID NO:15. In other instances, a 5′ UTR sequence provided in Table 3 has a first nucleotide which is a G. For example, the Attorney Docket No.: 45817-0174WO1 5’UTR of SEQ ID NO:50 with a G as the first nucleotide is the 5’UTR provided in SEQ ID NO:8. Table 3: 5′ UTR sequences SEQ ID Sequence Sequence NO: name U U C U U C G A U U U G C n Attorney Docket No.: 45817-0174WO1 (N4)x is a cytosine and x is an integer from 0 to 1; (N5)x is a uracil and x is an integer from 0 to 5, e.g., wherein U G A G U C C A Attorney Docket No.: 45817-0174WO1 72 A23 GGAAAUCGUAGAGAGUCGUACUUAGAAUAAACA GAGUCGGGUCGACUUGUCUCUGAUACUACGACGU C U G C A instance, the variant of SEQ ID NO: 50 comprises a nucleic acid sequence of Formula A: G G A A A U C G C A A A A (N2)X (N3)X C U (N4)X (N5)X C G C G U U A G A U U U C U U U U A G U U U U C U N6N7C A A C U A G C A A G C U U U U U G U U C U C G C C (N8 C C)x (SEQ ID NO: 59), wherein: (N2)xis a uracil and x is an integer from 0 to 5, e.g., wherein x =3 or 4; (N3)xis a guanine and x is an integer from 0 to 1; (N4)x is a cytosine and x is an integer from 0 to 1; (N5)xis a uracil and x is an integer from 0 to 5, e.g., wherein x =2 or 3; N6is a uracil or cytosine; N7 is a uracil or guanine; N8 is adenine or guanine and x is an integer from 0 to 1. Attorney Docket No.: 45817-0174WO1 In some cases, SEQ ID NO:59 includes an additional G nucleotide at the N-terminus. In some cases, SEQ ID NO:59 includes an A nucleotide at the N-terminus. In one case (N2)x is a uracil and x is 0. In one case (N2)x is a uracil and x is 1. In an instance (N2)xis a uracil and x is 2. In one case (N2)xis a uracil and x is 3. In an instance, (N2)xis a uracil and x is 4. In one case (N2)xis a uracil and x is 5. In one case, (N3)x is a guanine and x is 0. In one case, (N3)x is a guanine and x is 1. In one case, (N4)xis a cytosine and x is 0. In one case, (N4)xis a cytosine and x is 1. In one case (N5)x is a uracil and x is 0. In one case (N5)x is a uracil and x is 1. In one case (N5)xis a uracil and x is 2. In one case (N5)xis a uracil and x is 3. In one case, (N5)xis a uracil and x is 4. In one case (N5)xis a uracil and x is 5. In one case, N6 is a uracil. In one case, N6 is a cytosine. In one case, N7is a uracil. In one case, N7is a guanine. In one case, N8is an adenine and x is 0. In one case, N8is an adenine and x is 1. In one case, N8 is a guanine and x is 0. In one case, N8 is a guanine and x is 1. In a different instance, the 5′ UTR comprises a variant of SEQ ID NO: 58. In one case, the variant of SEQ ID NO: 58 comprises a sequence with at least 58%, 60%, 70%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, or 99% identity to SEQ ID NO: 58. In another case, the variant of SEQ ID NO: 58 comprises a sequence with at least 58% identity to SEQ ID NO: 58. In another case, the variant of SEQ ID NO: 58 comprises a sequence with at least 60% identity to SEQ ID NO: 58. In another case, the variant of SEQ ID NO: 58 comprises a sequence with at least 70% identity to SEQ ID NO: 58. In another case, the variant of SEQ ID NO: 58 comprises a sequence with at least 80% identity to SEQ ID NO: 58. In another case, the variant of SEQ ID NO: 58 comprises a sequence with at least 90% identity to SEQ ID NO: 58. In another case, the variant of SEQ ID NO: 58 comprises a sequence with at least 95% identity to SEQ ID NO: 58. In another case, the variant of SEQ ID NO: 58 comprises a sequence with at least 96% identity to SEQ ID NO: 58. In another case, the variant of SEQ ID NO: 58 comprises a sequence with at Attorney Docket No.: 45817-0174WO1 least 97% identity to SEQ ID NO: 58. In another case, the variant of SEQ ID NO: 58 comprises a sequence with at least 98% identity to SEQ ID NO: 58. In another case, the variant of SEQ ID NO: 58 comprises a sequence with at least 99% identity to SEQ ID NO: 58. In another case, the variant of SEQ ID NO: 58 comprises a uridine content of at least 5%, 10%, 20%, 30%, 40%, 58%, 60%, 70%, or 80%. In another case, the variant of SEQ ID NO: 58 comprises a uridine content of at least 5%. In another case, the variant of SEQ ID NO: 58 comprises a uridine content of at least 10%. In another case, the variant of SEQ ID NO: 58 comprises a uridine content of at least 20%. In another case, the variant of SEQ ID NO: 58 comprises a uridine content of at least 30%. In another case, the variant of SEQ ID NO: 58 comprises a uridine content of at least 40%. In another case, the variant of SEQ ID NO: 58 comprises a uridine content of at least 58%. In another case, the variant of SEQ ID NO: 58 comprises a uridine content of at least 60%. In another case, the variant of SEQ ID NO: 58 comprises a uridine content of at least 70%. In another case, the variant of SEQ ID NO: 58 comprises a uridine content of at least 80%. In some instances, the variant of SEQ ID NO: 58 comprises at least 2, 3, 4, 5, 6 or 7 consecutive uridines (e.g., a polyuridine tract). In one case, the polyuridine tract in the variant of SEQ ID NO: 58 comprises at least 1-7, 2-7, 3-7, 4-7, 5-7, 6-7, 1-6, 1-5, 1-4, 1- 3, 1-2, 2-6, or 3-5 consecutive uridines. In another case, the polyuridine tract in the variant of SEQ ID NO: 58 comprises 4 consecutive uridines. In yet another case, the polyuridine tract in the variant of SEQ ID NO: 58 comprises 5 consecutive uridines. In another instance, the variant of SEQ ID NO: 58 comprises 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 polyuridine tracts. In one case, the variant of SEQ ID NO: 58 comprises 3 polyuridine tracts. In another case, the variant of SEQ ID NO: 58 comprises 4 polyuridine tracts. In another case, the variant of SEQ ID NO: 58 comprises 5 polyuridine tracts. In another case, one or more of the polyuridine tracts are adjacent to a different polyuridine tract. In yet another case, each of, e.g., all, the polyuridine tracts are adjacent to each other, e.g., all of the polyuridine tracts are contiguous. Attorney Docket No.: 45817-0174WO1 In some instances, one or more of the polyuridine tracts are separated by 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 2, 13, 14, 15, 16, 17, 18.19, 20, 30, 40, 50 or 60 nucleotides. In one case, each of, e.g., all of, the polyuridine tracts are separated by 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 2, 13, 14, 15, 16, 17, 18.19, 20, 30, 40, 50 or 60 nucleotides. In one instance, a first polyuridine tract and a second polyuridine tract are adjacent to each other. In another instance, a subsequent, e.g., third, fourth, fifth, sixth or seventh, eighth, ninth, or tenth, polyuridine tract is separated by 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 2, 13, 14, 15, 16, 17, 18.19, 20, 30, 40, 50 or 60 nucleotides from the first polyuridine tract, the second polyuridine tract, or any one of the subsequent polyuridine tracts. In another instance, a first polyuridine tract is separated by 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 2, 13, 14, 15, 16, 17, 18.19, 20, 30, 40, 50 or 60 nucleotides from a subsequent polyuridine tract, e.g., a second, third, fourth, fifth, sixth or seventh, eighth, ninth, or tenth polyuridine tract. In an instance, one or more of the subsequent polyuridine tracts are adjacent to a different polyuridine tract. In yet another instance, the 5′ UTR comprises a Kozak sequence, e.g., a GCCRCC nucleotide sequence wherein R is an adenine or guanine. In one case, the Kozak sequence is disposed at the 3′ end of the 5′UTR sequence. In another aspect, the polynucleotide (e.g., mRNA) comprising an open reading frame encoding a fusion protein of the disclosure and comprising a 5′ UTR sequence disclosed herein is formulated as an LNP. In one instance, the LNP composition comprises: (i) an ionizable amino lipid, e.g., an amino lipid; (ii) a sterol or other structural lipid; (iii) a non-cationic helper lipid or phospholipid; and (iv) a PEG-lipid. In some cases, the LNP comprises sialic acid. In certain cases, the LNP is co-administered with sialic acid. In another aspect, the LNP compositions of the disclosure are used in a method of promoting or inducing tolerance to the antigen of the fusion protein in a subject. Attorney Docket No.: 45817-0174WO1 In another aspect, an LNP composition comprising a polynucleotide disclosed herein encoding a fusion protein described herein, can be administered with an additional agent, e.g., as described herein. 3′ UTR sequences 3′UTR sequences have been shown to influence translation, half-life, and subcellular localization of mRNAs (Mayr C., Cold Spring Harb Persp Biol 2019 Oct 1;11(10):a034728). Disclosed herein, inter alia, is a polynucleotide, e.g., mRNA, comprising an open reading frame encoding a fusion protein described herein, which polynucleotide has a 3′ UTR that confers an increased half-life, increased expression and / or increased activity of the polypeptide encoded by said polynucleotide, or of the polynucleotide itself. In one instance, a polynucleotide disclosed herein comprises: (a) a 5′-UTR (e.g., as described herein); (b) a coding region comprising a stop element (e.g., as described herein); and (c) a 3′-UTR (e.g., as provided in Table 3 or a variant or fragment thereof), and LNP compositions comprising the same. In one instance, the polynucleotide comprises a 3′- UTR comprising a sequence provided in Table 3, SEQ ID NO: 9, SEQ ID NO:16, or a variant or fragment thereof. In one instance, the polynucleotide having a 3′ UTR sequence provided in Table 3, SEQ ID NO: 9, SEQ ID NO:16, or a variant or fragment thereof, results in an increased half-life of the polynucleotide, e.g., about 1.5-10-fold increase in half-life of the polynucleotide. In one case, the increase in half-life is about 1.5, 2, 3, 4, 5, 6, 7, 8, 9, or 10-fold, or more. In another case, the increase in half-life is about 1.5-fold or more. In a further case, the increase in half-life is about 2-fold or more. In an another case, the increase in half-life is about 3-fold or more. In yet another case, the increase in half-life is about 4-fold or more. In another case, the increase in half-life is about 5-fold or more. In an another case, the increase in half-life is about 6-fold or more. In a further case, the increase in half-life is about 7-fold or more. In another case, the increase in half-life is Attorney Docket No.: 45817-0174WO1 about 8-fold. In yet another case, the increase in half-life is about 9-fold or more. In another case, the increase in half-life is about 10-fold or more. In another instance, the polynucleotide having a 3′ UTR sequence provided in Table 4, SEQ ID NO: 9, SEQ ID NO:16, or a variant or fragment thereof, results in a polynucleotide with a mean half-life score of greater than 10. In another instance, the polynucleotide having a 3′ UTR sequence provided in Table 4, SEQ ID NO: 9, SEQ ID NO:16, or a variant or fragment thereof, results in an increased level and / or activity, e.g., output, of the polypeptide encoded by the polynucleotide. In another instance, the increase is compared to an otherwise similar polynucleotide which does not have a 3′ UTR, has a different 3′ UTR, or does not have a 3′ UTR of Table 4, SEQ ID NO: 9, SEQ ID NO:16, or a variant or fragment thereof. In another instance, the polynucleotide comprises a 3′ UTR sequence provided in Table 4, SEQ ID NO: 9, SEQ ID NO:16, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to a 3′ UTR sequence provided in Table 4, SEQ ID NO: 9, SEQ ID NO:16, or a fragment thereof. In one case, the 3′ UTR comprises a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 100, SEQ ID NO: 101, SEQ ID NO: 102, SEQ ID NO: 103, SEQ ID NO: 104, SEQ ID NO: 105, SEQ ID NO: 106, SEQ ID NO: 107, SEQ ID NO: 108, SEQ ID NO: 109, SEQ ID NO: 110, SEQ ID NO: 111, SEQ ID NO: 112, SEQ ID NO: 113, SEQ ID NO: 114, SEQ ID NO:115, SEQ ID NO:137, SEQ ID NO: 9, or SEQ ID NO:16. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 100, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 100. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 101, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 101. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 102, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 102. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 103, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or Attorney Docket No.: 45817-0174WO1 100% identity to SEQ ID NO: 103. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 104, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 104. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 105, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 105. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 106, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 106. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 107, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 107. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 108, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 108. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 109, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 109. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 110, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 110. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 111, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 111. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 112, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 112. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 113, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 113. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 114, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 114. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 115, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 115. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 137, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 137. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 9, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% Attorney Docket No.: 45817-0174WO1 identity to SEQ ID NO: 9. In one case, the 3′ UTR comprises the sequence of SEQ ID NO: 16, or a sequence with at least 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or 100% identity to SEQ ID NO: 16. Table 4: 3′ UTR sequences SEQ Sequence Sequence ID information C A G U U U Attorney Docket No.: 45817-0174WO1 B10 UGAUAAUAGGCUGGAGCCUCGGUGGCCUAGCUUCUU GCCCCUUGGGCCUCCCCCCAGCCCCUCCUCCCCUUCC A A C A C C C C G G A C A G Attorney Docket No.: 45817-0174WO1 GCUGGGGCUUGGUCAUGGGCCAUCAGCGCGUGCGUG GAACCUUUUCGGCUCCUCUGCCGAUCCAUACUGCGGA U U G U U G U C A C G U U G A Attorney Docket No.: 45817-0174WO1 140 B26 UAAGCCCCUCCGGGGGCCUCCACCGCGUUAUCCGUUC CUCGUAGGCUGGUCCUGGGGAACGGGUCGGCGGGUA C e.g., as described herein, which binds to a miR present in a human cell. In one case, the 3′ UTR comprises a miRNA binding site of SEQ ID NO: 154, SEQ ID NO: 155, SEQ ID NO: 152 or a combination thereof. In another case, the 3′ UTR comprises a plurality of miRNA binding sites, e.g., 2, 3, 4, 5, 6, 7 or 8 miRNA binding sites. In one case, the 3′ UTR comprises 3 miRNA12 binding sites (SEQ ID NO:154). In another case, the 3′ UTR comprises 3 miRNA142 binding sites (SEQ ID NO:155). In some cases, the plurality of miRNA binding sites comprises the same or different miRNA binding sites. miR122 bs = CAAACACCAUUGUCACACUCCA (SEQ ID NO: 154) miR-142-3p bs = UCCAUAAAGUAGGAAACACUACA (SEQ ID NO: 155) miR-126 bs = CGCAUUAUUACUCACGGUACGA (SEQ ID NO: 152) In some instances, disclosed herein is a polynucleotide encoding a polypeptide, wherein the polynucleotide comprises: (a) a 5′-UTR, e.g., as described herein; (b) a coding region comprising a stop element (e.g., as described herein); and (c) a 3′-UTR (e.g., as described herein). In certain instances, an LNP composition comprising a polynucleotide comprising an open reading frame encoding a fusion protein described herein and comprising a 3′ UTR disclosed herein comprises: (i) an ionizable amino lipid, e.g., an amino lipid; (ii) a sterol or other structural lipid; (iii) a non-cationic helper lipid or phospholipid; and (iv) a PEG-lipid. In some cases, the LNP comprises sialic acid. In other cases, the LNP is co- administered with sialic acid. In one instance, the LNP compositions of the disclosure are used in a method of inducing or promoting tolerance to an antigen in a subject. In another instance, an LNP composition comprising a polynucleotide disclosed herein encoding a fusion protein described herein, can be administered with an additional agent, e.g., as described herein. Attorney Docket No.: 45817-0174WO1 Regions having a 5′ Cap The disclosure also includes a polynucleotide that comprises both a 5′ Cap and a polynucleotide of the present disclosure (e.g., a polynucleotide comprising a nucleotide sequence encoding a fusion protein described herein to be expressed). The 5′ cap structure of a natural mRNA is involved in nuclear export, increasing mRNA stability and binds the mRNA Cap Binding Protein (CBP), which is responsible for mRNA stability in the cell and translation competency through the association of CBP with poly A binding protein to form the mature cyclic mRNA species. The cap further assists the removal of 5′ proximal introns during mRNA splicing. Endogenous mRNA molecules can be 5′-end capped generating a 5′-ppp-5′- triphosphate linkage between a terminal guanosine cap residue and the 5′-terminal transcribed sense nucleotide of the mRNA molecule. This 5′-guanylate cap can then be methylated to generate an N7-methyl-guanylate residue. The ribose sugars of the terminal and / or anteterminal transcribed nucleotides of the 5′ end of the mRNA can optionally also be 2′-O-methylated.5′-decapping through hydrolysis and cleavage of the guanylate cap structure can target a nucleic acid molecule, such as an mRNA molecule, for degradation. In some instances, the polynucleotides of the present disclosure (e.g., a polynucleotide comprising a nucleotide sequence encoding a fusion protein described herein) incorporate a cap moiety. In some instances, polynucleotides of the present disclosure comprise a non- hydrolyzable cap structure preventing decapping and thus increasing mRNA half-life. Because cap structure hydrolysis requires cleavage of 5′-ppp-5′ phosphorodiester linkages, modified nucleotides can be used during the capping reaction. For example, a Vaccinia Capping Enzyme from New England Biolabs (Ipswich, MA) can be used with α-thio-guanosine nucleotides according to the manufacturer's instructions to create a phosphorothioate linkage in the 5′-ppp-5′ cap. Additional modified guanosine nucleotides can be used such as α-methyl-phosphonate and seleno-phosphate nucleotides. Attorney Docket No.: 45817-0174WO1 Additional modifications include, but are not limited to, 2′-O-methylation of the ribose sugars of 5′-terminal and / or 5′-anteterminal nucleotides of the polynucleotide (as mentioned above) on the 2′-hydroxyl group of the sugar ring. Multiple distinct 5′-cap structures can be used to generate the 5′-cap of a nucleic acid molecule, such as a polynucleotide that functions as an mRNA molecule. Cap analogs, which herein are also referred to as synthetic cap analogs, chemical caps, chemical cap analogs, or structural or functional cap analogs, differ from natural (i.e., endogenous, wild-type or physiological) 5′-caps in their chemical structure, while retaining cap function. Cap analogs can be chemically (i.e., non-enzymatically) or enzymatically synthesized and / or linked to the polynucleotides of the disclosure. For example, the Anti-Reverse Cap Analog (ARCA) cap contains two guanines linked by a 5′-5′-triphosphate group, wherein one guanine contains an N7 methyl group as well as a 3′-O-methyl group (i.e., N7,3′-O-dimethyl-guanosine-5′-triphosphate-5′- guanosine (m7G-3′mppp-G; which can equivalently be designated 3′ O-Me- m7G(5′)ppp(5′)G). The 3′-O atom of the other, unmodified, guanine becomes linked to the 5′-terminal nucleotide of the capped polynucleotide. The N7- and 3′-O-methlyated guanine provides the terminal moiety of the capped polynucleotide. Another exemplary cap is mCAP, which is similar to ARCA but has a 2′-O- methyl group on guanosine (i.e., N7,2′-O-dimethyl-guanosine-5′-triphosphate-5′- guanosine, m7Gm-ppp-G). Another exemplary cap is m7G-ppp-Gm-A (i.e., N7,guanosine-5′-triphosphate-2′-O- dimethyl-guanosine-adenosine). In some instances, the cap is a dinucleotide cap analog. As a non-limiting example, the dinucleotide cap analog can be modified at different phosphate positions with a boranophosphate group or a phosphoroselenoate group such as the dinucleotide cap analogs described in U.S. Patent No. US 8,519,110, the contents of which are herein incorporated by reference in its entirety. In another instance, the cap is a cap analog is a N7-(4-chlorophenoxyethyl) substituted dinucleotide form of a cap analog known in the art and / or described herein. Attorney Docket No.: 45817-0174WO1 Non-limiting examples of a N7-(4-chlorophenoxyethyl) substituted dinucleotide form of a cap analog include a N7-(4-chlorophenoxyethyl)-G(5′)ppp(5′)G and a N7-(4- chlorophenoxyethyl)-m3′-OG(5′)ppp(5′)G cap analog (See, e.g., the various cap analogs and the methods of synthesizing cap analogs described in Kore et al. Bioorganic & Medicinal Chemistry 201321:4570-4574; the contents of which are herein incorporated by reference in its entirety). In another instance, a cap analog of the present disclosure is a 4-chloro / bromophenoxyethyl analog. Polynucleotides of the disclosure can also be capped post-manufacture (whether IVT or chemical synthesis), using enzymes, in order to generate more authentic 5′-cap structures. As used herein, the phrase "more authentic" refers to a feature that closely mirrors or mimics, either structurally or functionally, an endogenous or wild type feature. That is, a "more authentic" feature is better representative of an endogenous, wild-type, natural or physiological cellular function and / or structure as compared to synthetic features or analogs, etc., of the prior art, or which outperforms the corresponding endogenous, wild-type, natural or physiological feature in one or more respects. Non- limiting examples of more authentic 5′cap structures of the present disclosure are those that, among other things, have enhanced binding of cap binding proteins, increased half- life, reduced susceptibility to 5′ endonucleases and / or reduced 5′decapping, as compared to synthetic 5′cap structures known in the art (or to a wild-type, natural or physiological 5′cap structure). For example, recombinant Vaccinia Virus Capping Enzyme and recombinant 2′-O-methyltransferase enzyme can create a canonical 5′-5′-triphosphate linkage between the 5′-terminal nucleotide of a polynucleotide and a guanine cap nucleotide wherein the cap guanine contains an N7 methylation and the 5′-terminal nucleotide of the mRNA contains a 2′-O-methyl. Such a structure is termed the Cap1 structure. This cap results in a higher translational-competency and cellular stability and a reduced activation of cellular pro-inflammatory cytokines, as compared, e.g., to other 5′cap analog structures known in the art. Cap structures include, but are not limited to, 7mG(5′)ppp(5′)N1pN2p (cap 0), 7mG(5′)ppp(5′)N1mpNp (cap 1), and 7mG(5′)- ppp(5′)N1mpN2mp (cap 2). Attorney Docket No.: 45817-0174WO1 As a non-limiting example, capping chimeric polynucleotides post-manufacture can be more efficient as nearly 100% of the chimeric polynucleotides can be capped. This is in contrast to ~80% when a cap analog is linked to a chimeric polynucleotide in the course of an in vitro transcription reaction. According to the present disclosure, 5′ terminal caps can include endogenous caps or cap analogs. A 5′ terminal cap can comprise a guanine analog. Useful guanine analogs include, but are not limited to, inosine, N1-methyl-guanosine, 2′fluoro-guanosine, 7- deaza-guanosine, 8-oxo-guanosine, 2-amino-guanosine, LNA-guanosine, and 2-azido- guanosine. Also provided herein are exemplary caps including those that can be used in co- transcriptional capping methods for ribonucleic acid (RNA) synthesis, using RNA polymerase, e.g., wild type RNA polymerase or variants thereof, e.g., such as those variants described herein. In one instance, caps can be added when RNA is produced in a “one-pot” reaction, without the need for a separate capping reaction. Thus, the methods, in some instances, comprise reacting a polynucleotide template with an RNA polymerase variant, nucleoside triphosphates, and a cap analog under in vitro transcription reaction conditions to produce RNA transcript. As used here the term “cap” includes the inverted G nucleotide and can comprise one or more additional nucleotides 3′ of the inverted G nucleotide, e.g., 1, 2, 3, or more nucleotides 3′ of the inverted G nucleotide and 5′ to the 5′ UTR, e.g., a 5′ UTR described herein. Exemplary caps comprise a sequence of GG, GA, or GGA, wherein the underlined, italicized G is an in inverted G nucleotide followed by a 5′-5′-triphosphate group. In one instance, a cap comprises a compound of formula (I) Attorney Docket No.: 45817-0174WO1 ring B2 and ring B3 each independently is a nucleobase or a modified nucleobase; X2 is O, S(O)p, NR24 or CR25R26 in which p is 0, 1, or 2; Y0is O or CR6R7; Y1 is O, S(O)n, CR6R7, or NR8, in which n is 0, 1 , or 2; each --- is a single bond or absent, wherein when each --- is a single bond, Yi is O, S(O)n, CR6R7, or NR8; and when each --- is absent, Y1is void; Y2 is (OP(O)R4)m in which m is 0, 1, or 2, or -O-(CR40R41)u-Q0-(CR42R43)v-, in which Q0 is a bond, O, S(O)r, NR44, or CR45R46, r is 0, 1 , or 2, and each of u and v independently is 1, 2, 3 or 4; each R2and R2′ independently is halo, LNA, or OR3; each R3 independently is H, C1-C6 alkyl, C2-C6 alkenyl, or C2-C6 alkynyl and R3, when being C1-C6 alkyl, C2-C6 alkenyl, or C2-C6 alkynyl, is optionally substituted Attorney Docket No.: 45817-0174WO1 with one or more of halo, OH and C1-C6 alkoxyl that is optionally substituted with one or more OH or OC(O)-C1-C6 alkyl; each R4 and R4′ independently is H, halo, C1-C6 alkyl, OH, SH, SeH, or BH3-; each of R6, R7, and R8, independently, is -Q1-T1, in which Q1is a bond or C1-C3 alkyl linker optionally substituted with one or more of halo, cyano, OH and C1-C6 alkoxy, and T1 is H, halo, OH, COOH, cyano, or Rs1, in which Rs1 is C1-C3 alkyl, C2- C6 alkenyl, C2-C6 alkynyl, C1- C6 alkoxyl, C(O)O-C1-C6 alkyl, C3-C8 cycloalkyl, C6- C10 aryl, NR31R32, (NR31R32R33)+, 4 to 12- membered heterocycloalkyl, or 5- or 6- membered heteroaryl, and Rs1 is optionally substituted with one or more substituents selected from the group consisting of halo, OH, oxo, C1-C6 alkyl, COOH, C(O)O-C1- C6 alkyl, cyano, C1-C6 alkoxyl, NR31R32, (NR31R32R33)+, C3-C8 cycloalkyl, C6- C10 aryl, 4 to 12-membered heterocycloalkyl, and 5- or 6-membered heteroaryl; each of R10, R11, R12, R13, R14, and R15, independently, is -Q2-T2, in which Q2 is a bond or C1-C3 alkyl linker optionally substituted with one or more of halo, cyano, OH and C1-C6 alkoxy, and T2is H, halo, OH, NH2, cyano, NO2, N3, Rs2, or ORs2, in which Rs2 is C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C8 cycloalkyl, C6-C10 aryl, NHC(O)-C1-C6 alkyl, NR31R32, (NR31R32R33)+, 4 to 12-membered heterocycloalkyl, or 5- or 6-membered heteroaryl, and Rs2 is optionally substituted with one or more substituents selected from the group consisting of halo, OH, oxo, C1-C6 alkyl, COOH, C(O)O-C1-C6 alkyl, cyano, C1 - C6 alkoxyl, NR31R32, (NR31R32R33)+, C3- C8 cycloalkyl, C6-C10 aryl, 4 to 12-membered heterocycloalkyl, and 5- or 6- membered heteroaryl; or alternatively R12 together with R14 is oxo, or R13 together with R15 is oxo, each of R20, R21, R22, and R23 independently is -Q3-T3, in which Q3 is a bond or C1-C3 alkyl linker optionally substituted with one or more of halo, cyano, OH and C1-C6 alkoxy, and T3is H, halo, OH, NH2, cyano, NO2, N3, RS3, or ORS3, in which RS3 is C1- C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, C3-C8 cycloalkyl, C6-C10 aryl, NHC(O)-C1- C6 alkyl, mono-C1-C6 alkylamino, di-C1-C6 alkylamino, 4 to 12-membered heterocycloalkyl, or 5- or 6-membered heteroaryl, and Rs3 is optionally substituted with one or more substituents selected from the group consisting of halo, OH, oxo, C1-C6 Attorney Docket No.: 45817-0174WO1 alkyl, COOH, C(O)O-C1-C6 alkyl, cyano, C1-C6 alkoxyl, amino, mono-C1-C6 alkylamino, di-C1-C6 alkylamino, C3-C8 cycloalkyl, C6-C10 aryl, 4 to 12-membered heterocycloalkyl, and 5- or 6-membered heteroaryl; each of R24, R25, and R26independently is H or C1-C6 alkyl; each of R27and R28independently is H or OR29; or R27and R28together form O- R30-O; each R29 independently is H, C1-C6 alkyl, C2-C6 alkenyl, or C2-C6 alkynyl and R29, when being C1-C6 alkyl, C2-C6 alkenyl, or C2-C6 alkynyl, is optionally substituted with one or more of halo, OH and C1-C6 alkoxyl that is optionally substituted with one or more OH or OC(O)-C1-C6 alkyl; R30 is C1-C6 alkylene optionally substituted with one or more of halo, OH and C1-C6 alkoxyl; each of R31, R32, and R33, independently is H, C1-C6 alkyl, C3-C8 cycloalkyl, C6-C10 aryl, 4 to 12-membered heterocycloalkyl, or 5- or 6-membered heteroaryl; each of R40, R41, R42, and R43independently is H, halo, OH, cyano, N3, OP(O)R47R48, or C1-C6 alkyl optionally substituted with one or more OP(O)R47R48, or one R41 and one R43, together with the carbon atoms to which they are attached and Q0, form C4-C10 cycloalkyl, 4- to 14-membered heterocycloalkyl, C6-C10 aryl, or 5- to 14- membered heteroaryl, and each of the cycloalkyl, heterocycloalkyl, phenyl, or 5- to 6- membered heteroaryl is optionally substituted with one or more of OH, halo, cyano, N3, oxo, OP(O)R47R48, C1-C6 alkyl, C1-C6 haloalkyl, COOH, C(O)O-C1-C6 alkyl, C1-C6 alkoxyl, C1-C6 haloalkoxyl, amino, mono-C1-C6 alkylamino, and di-C1-C6 alkylamino; R44 is H, C1-C6 alkyl, or an amine protecting group; each of R45 and R46 independently is H, OP(O)R47R48, or C1-C6 alkyl optionally substituted with one or more OP(O)R47R48, and each of R47and R48, independently is H, halo, C1-C6 alkyl, OH, SH, SeH, or BH3. It should be understood that a cap analog, as provided herein, may include any of the cap analogs described in international publication WO 2017 / 066797, published on 20 April 2017, incorporated by reference herein in its entirety. Attorney Docket No.: 45817-0174WO1 In some instances, the B2middle position can be a non-ribose molecule, such as arabinose. In some instances, R2 is ethyl-based. Thus, in some instances, a cap comprises the following structure: In other instances, a cap comprises the following structure:

[0003] Attorney Docket No.: 45817-0174WO1 In yet other instances, a cap comprises the following structure: In still other instances, a cap comprises the following structure: In some instances, R is an alkyl (e.g., C1-C6 alkyl). In some instances, R is a methyl group (e.g., C1 alkyl). In some instances, R is an ethyl group (e.g., C2 alkyl). Attorney Docket No.: 45817-0174WO1 In some instances, a cap comprises a sequence selected from the following sequences: GAA, GAC, GAG, GAU, GCA, GCC, GCG, GCU, GGA , GGC, GGG, GGU, GUA, GUC, GUG, and GUU. In some instances, a cap comprises GAA. In some instances, a cap comprises GAC. In some instances, a cap comprises GAG. In some instances, a cap comprises GAU. In some instances, a cap comprises GCA. In some instances, a cap comprises GCC. In some instances, a cap comprises GCG. In some instances, a cap comprises GCU. In some instances, a cap comprises GGA. In some instances, a cap comprises GGC. In some instances, a cap comprises GGG. In some instances, a cap comprises GGU. In some instances, a cap comprises GUA. In some instances, a cap comprises GUC. In some instances, a cap comprises GUG. In some instances, a cap comprises GUU. In some instances, a cap comprises a sequence selected from the following sequences: m7GpppApA, m7GpppApC, m7GpppApG, m7GpppApU, m7GpppCpA, m7GpppCpC, m7GpppCpG, m7GpppCpU, m7GpppGpA, m7GpppGpC, m7GpppGpG, m7GpppGpU, m7GpppUpA, m7GpppUpC, m7GpppUpG, and m7GpppUpU. In some instances, a cap comprises m7GpppApA. In some instances, a cap comprises m7GpppApC. In some instances, a cap comprises m7GpppApG. In some instances, a cap comprises m7GpppApU. In some instances, a cap comprises m7GpppCpA. In some instances, a cap comprises m7GpppCpC. In some instances, a cap comprises m7GpppCpG. In some instances, a cap comprises m7GpppCpU. In some instances, a cap comprises m7GpppGpA. In some instances, a cap comprises m7GpppGpC. In some instances, a cap comprises m7GpppGpG. In some instances, a cap comprises m7GpppGpU. In some instances, a cap comprises m7GpppUpA. In some instances, a cap comprises m7GpppUpC. In some instances, a cap comprises m7GpppUpG. In some instances, a cap comprises m7GpppUpU. A cap, in some instances, comprises a sequence selected from the following sequences: m7G3^OMepppApA, m7G3^OMepppApC, m7G3^OMepppApG, m7G3^OMepppApU, m7G3^OMepppCpA, m7G3^OMepppCpC, m7G3^OMepppCpG, m7G3^OMepppCpU, m7G3^OMepppGpA, m7G3^OMepppGpC, m7G3^OMepppGpG, Attorney Docket No.: 45817-0174WO1 m7G3^OMepppGpU, m7G3^OMepppUpA, m7G3^OMepppUpC, m7G3^OMepppUpG, and m7G3^OMepppUpU. In some instances, a cap comprises m7G3^OMepppApA. In some instances, a cap comprises m7G3^OMepppApC. In some instances, a cap comprises m7G3^OMepppApG. In some instances, a cap comprises m7G3^OMepppApU. In some instances, a cap comprises m7G3^OMepppCpA. In some instances, a cap comprises m7G3^OMepppCpC. In some instances, a cap comprises m7G3^OMepppCpG. In some instances, a cap comprises m7G3^OMepppCpU. In some instances, a cap comprises m7G3^OMepppGpA. In some instances, a cap comprises m7G3^OMepppGpC. In some instances, a cap comprises m7G3^OMepppGpG. In some instances, a cap comprises m7G3^OMepppGpU. In some instances, a cap comprises m7G3^OMepppUpA. In some instances, a cap comprises m7G3^OMepppUpC. In some instances, a cap comprises m7G3^OMepppUpG. In some instances, a cap comprises m7G3^OMepppUpU. A cap, in other instances, comprises a sequence selected from the following sequences: m7G3^OMepppA2^OMepA, m7G3^OMepppA2^OMepC, m7G3^OMepppA2^OMepG, m7G3^OMepppA2^OMepU, m7G3^OMepppC2^OMepA, m7G3^OMepppC2^OMepC, m7G3^OMepppC2^OMepG, m7G3^OMepppC2^OMepU, m7G3^OMepppG2^OMepA, m7G3^OMepppG2^OMepC, m7G3^OMepppG2^OMepG, m7G3^OMepppG2^OMepU, m7G3^OMepppU2^OMepA, m7G3^OMepppU2^OMepC, m7G3^OMepppU2^OMepG, and m7G3^OMepppU2^OMepU. In some instances, a cap comprises m7G3^OMepppA2^OMepA. In some instances, a cap comprises m7G3^OMepppA2^OMepC. In some instances, a cap comprises m7G3^OMepppA2^OMepG. In some instances, a cap comprises m7G3^OMepppA2^OMepU. In some instances, a cap comprises m7G3^OMepppC2^OMepA. In some instances, a cap comprises m7G3^OMepppC2^OMepC. In some instances, a cap comprises m7G3^OMepppC2^OMepG. In some instances, a cap comprises m7G3^OMepppC2^OMepU. In some instances, a cap comprises m7G3^OMepppG2^OMepA. In some instances, a cap Attorney Docket No.: 45817-0174WO1 comprises m7G3^OMepppG2^OMepC. In some instances, a cap comprises m7G3^OMepppG2^OMepG. In some instances, a cap comprises m7G3^OMepppG2^OMepU. In some instances, a cap comprises m7G3^OMepppU2^OMepA. In some instances, a cap comprises m7G3^OMepppU2^OMepC. In some instances, a cap comprises m7G3^OMepppU2^OMepG. In some instances, a cap comprises m7G3^OMepppU2^OMepU. A cap, in still other instances, comprises a sequence selected from the following sequences: m7GpppA2^OMepA, m7GpppA2^OMepC, m7GpppA2^OMepG, m7GpppA2^OMepU, m7GpppC2^OMepA, m7GpppC2^OMepC, m7GpppC2^OMepG, m7GpppC2^OMepU, m7GpppG2^OMepA, m7GpppG2^OMepC, m7GpppG2^OMepG, m7GpppG2^OMepU, m7GpppU2^OMepA, m7GpppU2^OMepC, m7GpppU2^OMepG, and m7GpppU2^OMepU. In some instances, a cap comprises m7GpppA2^OMepA. In some instances, a cap comprises m7GpppA2^OMepC. In some instances, a cap comprises m7GpppA2^OMepG. In some instances, a cap comprises m7GpppA2^OMepU. In some instances, a cap comprises m7GpppC2^OMepA. In some instances, a cap comprises m7GpppC2^OMepC. In some instances, a cap comprises m7GpppC2^OMepG. In some instances, a trinucleotide cap comprises m7GpppC2^OMepU. In some instances, a cap comprises m7GpppG2^OMepA. In some instances, a cap comprises m7GpppG2^OMepC. In some instances, a cap comprises m7GpppG2^OMepG. In some instances, a cap comprises m7GpppG2^OMepU. In some instances, a cap comprises m7GpppU2^OMepA. In some instances, a cap comprises m7GpppU2^OMepC. In some instances, a cap comprises m7GpppU2^OMepG. In some instances, a cap comprises m7GpppU2^OMepU. In some instances, a cap comprises m7Gpppm6A2′OmepG. In some instances, a cap comprises m7Gpppe6A2′OmepG. In some instances, a cap comprises GAG. In some instances, a cap comprises GCG. In some instances, a cap comprises GUG. In some instances, a cap comprises GGG. In some instances, a cap comprises any one of the following structures: Attorney Docket No.: 45817-0174WO1 or . In some instances, the cap comprises m7GpppN1N2N3, where N1, N2, and N3are optional (i.e., can be absent or one or more can be present) and are independently a natural, a modified, or an unnatural nucleoside base. In some instances,m7G is further methylated, e.g., at the 3′ position. In some instances, them7G comprises an O-methyl at the 3′ position. In some instances N1, N2, and N3if present, optionally, are independently an adenine, a uracil, a guanidine, a thymine, or a cytosine. In some instances, one or more (or all) of N1, N2, and N3, if present, are methylated, e.g., at the 2′ position. In some Attorney Docket No.: 45817-0174WO1 instances, one or more (or all) of N1, N2, and N3, if present have an O-methyl at the 2′ position. In some instances, the cap comprises the following structure: unnatural nucleoside based; and R1, R2, R3, and R4are independently OH or O-methyl. In some instances, R3 is O-methyl and R4 is OH. In some instances, R3 and R4 are O-methyl. In some instances, R4 is O-methyl. In some instances, R1 is OH, R2 is OH, R3 is O-methyl, and R4is OH. In some instances, R1is OH, R2is OH, R3is O-methyl, and R4is O- methyl. In some instances, at least one of R1 and R2 is O-methyl, R3 is O-methyl, and R4 is OH. In some instances, at least one of R1 and R2 is O-methyl, R3 is O-methyl, and R4 is O-methyl. In some instances, B1, B2, and B3are natural nucleoside bases. In some instances, at least one of B1, B2, and B3 is a modified or unnatural base. In some instances, at least one of B1, B2, and B3is N6-methyladenine. In some instances, B1is adenine, cytosine, thymine, or uracil. In some instances, B1is adenine, B2is uracil, and B3is adenine. In some instances, R1 and R2 are OH, R3 and R4 are O-methyl, B1 is adenine, B2 is uracil, and B3 is adenine. In some instances, the cap comprises a sequence selected from the following sequences: GAAA, GACA, GAGA, GAUA, GCAA, GCCA, GCGA, GCUA, GGAA, Attorney Docket No.: 45817-0174WO1 GGCA, GGGA, GGUA, GUCA, and GUUA. In some instances, the cap comprises a sequence selected from the following sequences: GAAG, GACG, GAGG, GAUG, GCAG, GCCG, GCGG, GCUG, GGAG, GGCG, GGGG, GGUG, GUCG, GUGG, and GUUG. In some instances, the cap comprises a sequence selected from the following sequences: GAAU, GACU, GAGU, GAUU, GCAU, GCCU, GCGU, GCUU, GGAU, GGCU, GGGU, GGUU, GUAU, GUCU, GUGU, and GUUU. In some instances, the cap comprises a sequence selected from the following sequences: GAAC, GACC, GAGC, GAUC, GCAC, GCCC, GCGC, GCUC, GGAC, GGCC, GGGC, GGUC, GUAC, GUCC, GUGC, and GUUC. A cap, in some instances, comprises a sequence selected from the following sequences: m7G3^OMepppApApN, m7G3^OMepppApCpN, m7G3^OMepppApGpN, m7G3^OMepppApUpN, m7G3^OMepppCpApN, m7G3^OMepppCpCpN, m7G3^OMepppCpGpN, m7G3^OMepppCpUpN, m7G3^OMepppGpApN, m7G3^OMepppGpCpN, m7G3^OMepppGpGpN, m7G3^OMepppGpUpN, m7G3^OMepppUpApN, m7G3^OMepppUpCpN, m7G3^OMepppUpGpN, and m7G3^OMepppUpUpN, where N is a natural, a modified, or an unnatural nucleoside base. A cap, in other instances, comprises a sequence selected from the following sequences: m7G3^OMepppA2^OMepApN, m7G3^OMepppA2^OMepCpN, m7G3^OMepppA2^OMepGpN, m7G3^OMepppA2^OMepUpN, m7G3^OMepppC2^OMepApN, m7G3^OMepppC2^OMepCpN, m7G3^OMepppC2^OMepGpN, m7G3^OMepppC2^OMepUpN, m7G3^OMepppG2^OMepApN, m7G3^OMepppG2^OMepCpN, m7G3^OMepppG2^OMepGpN, m7G3^OMepppG2^OMepUpN, m7G3^OMepppU2^OMepApN, m7G3^OMepppU2^OMepCpN, m7G3^OMepppU2^OMepGpN, and m7G3^OMepppU2^OMepUpN, where N is a natural, a modified, or an unnatural nucleoside base. Attorney Docket No.: 45817-0174WO1 A cap, in still other instances, comprises a sequence selected from the following sequences: m7GpppA2^OMepApN, m7GpppA2^OMepCpN, m7GpppA2^OMepGpN, m7GpppA2^OMepUpN, m7GpppC2^OMepApN, m7GpppC2^OMepCpN, m7GpppC2^OMepGpN, m7GpppC2^OMepUpN, m7GpppG2^OMepApN, m7GpppG2^OMepCpN, m7GpppG2^OMepGpN, m7GpppG2^OMepUpN, m7GpppU2^OMepApN, m7GpppU2^OMepCpN, m7GpppU2^OMepGpN, and m7GpppU2^OMepUpN, where N is a natural, a modified, or an unnatural nucleoside base. A cap, in other instances, comprises a sequence selected from the following sequences: m7G3^OMepppA2^OMepA2^OMepN, m7G3^OMepppA2^OMepC2^OMepN, m7G3^OMepppA2^OMepG2^OMepN, m7G3^OMepppA2^OMepU2^OMepN, m7G3^OMepppC2^OMepA2^OMepN, m7G3^OMepppC2^OMepC2^OMepN, m7G3^OMepppC2^OMepG2^OMepN, m7G3^OMepppC2^OMepU2^OMepN, m7G3^OMepppG2^OMepA2^OMepN, m7G3^OMepppG2^OMepC2^OMepN, m7G3^OMepppG2^OMepG2^OMepN, m7G3^OMepppG2^OMepU2^OMepN, m7G3^OMepppU2^OMepA2^OMepN, m7G3^OMepppU2^OMepC2^OMepN, m7G3^OMepppU2^OMepG2^OMepN, and m7G3^OMepppU2^OMepU2^OMepN, where N is a natural, a modified, or an unnatural nucleoside base. A cap, in still other instances, comprises a sequence selected from the following sequences: m7GpppA2^OMepA2^OMepN, m7GpppA2^OMepC2^OMepN, m7GpppA2^OMepG2^OMepN, m7GpppA2^OMepU2^OMepN, m7GpppC2^OMepA2^OMepN, m7GpppC2^OMepC2^OMepN, m7GpppC2^OMepG2^OMepN, m7GpppC2^OMepU2^OMepN, m7GpppG2^OMepA2^OMepN, m7GpppG2^OMepC2^OMepN, m7GpppG2^OMepG2^OMepN, m7GpppG2^OMepU2^OMepN, m7GpppU2^OMepA2^OMepN, m7GpppU2^OMepC2^OMepN, m7GpppU2^OMepG2^OMepN, and m7GpppU2^OMepU2^OMepN, where N is a natural, a modified, or an unnatural nucleoside base. Attorney Docket No.: 45817-0174WO1 In some instances, a cap comprises GGAG. In some instances, a cap comprises the following structure: . Poly A Tails In some instances, the polynucleotides of the present disclosure (e.g., a polynucleotide comprising a nucleotide sequence encoding fusion protein described herein further comprise a poly A tail. In further instances, terminal groups on the poly A tail can be incorporated for stabilization. In other instances, a poly A tail comprises des-3′ hydroxyl tails. During RNA processing, a long chain of adenine nucleotides (poly A tail) can be added to a polynucleotide such as an mRNA molecule in order to increase stability. Immediately after transcription, the 3′ end of the transcript can be cleaved to free a 3′ hydroxyl. Then poly A polymerase adds a chain of adenine nucleotides to the RNA. The process, called poly Adenylation, adds a poly A tail that can be between, for example, approximately 80 to approximately 250 residues long, including approximately 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240 or 250 residues Attorney Docket No.: 45817-0174WO1 long. In one instance, the poly A tail is 100 nucleotides in length (SEQ ID NO:195). In some instances, the poly A tail can include an IDR sequence(s). Poly A tails can also be added after the construct is exported from the nucleus. According to the present disclosure, terminal groups on the poly A tail can be incorporated for stabilization. Polynucleotides of the present disclosure can include des-3′ hydroxyl tails. They can also include structural moieties or 2′-Omethyl modifications as taught by Junjie Li, et al. (Current Biology, Vol.15, 1501–1507, August 23, 2005, the contents of which are incorporated herein by reference in its entirety). The polynucleotides of the present disclosure can be designed to encode transcripts with alternative poly A tail structures including histone mRNA. According to Norbury, "Terminal uridylation has also been detected on human replication-dependent histone mRNAs. The turnover of these mRNAs is thought to be important for the prevention of potentially toxic histone accumulation following the completion or inhibition of chromosomal DNA replication. These mRNAs are distinguished by their lack of a 3ʹ poly A tail, the function of which is instead assumed by a stable stem–loop structure and its cognate stem–loop binding protein (SLBP); the latter carries out the same functions as those of PABP on poly Adenylated mRNAs" (Norbury, "Cytoplasmic RNA: a case of the tail wagging the dog," Nature Reviews Molecular Cell Biology; AOP, published online 29 August 2013; doi:10.1038 / nrm3645) the contents of which are incorporated herein by reference in its entirety. Unique poly A tail lengths provide certain advantages to the polynucleotides of the present disclosure. Generally, the length of a poly A tail, when present, is greater than 30 nucleotides in length. In another instance, the poly A tail is greater than 35 nucleotides in length (e.g., at least or greater than about 35, 40, 45, 50, 55, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1,000, 1,100, 1,200, 1,300, 1,400, 1,500, 1,600, 1,700, 1,800, 1,900, 2,000, 2,500, and 3,000 nucleotides). In some instances, the polynucleotide or region thereof includes from about 30 to about 3,000 nucleotides (e.g., from 30 to 50, from 30 to 100, from 30 to 250, from 30 to 500, from 30 to 750, from 30 to 1,000, from 30 to 1,500, from 30 to 2,000, from 30 to Attorney Docket No.: 45817-0174WO1 2,500, from 50 to 100, from 50 to 250, from 50 to 500, from 50 to 750, from 50 to 1,000, from 50 to 1,500, from 50 to 2,000, from 50 to 2,500, from 50 to 3,000, from 100 to 500, from 100 to 750, from 100 to 1,000, from 100 to 1,500, from 100 to 2,000, from 100 to 2,500, from 100 to 3,000, from 500 to 750, from 500 to 1,000, from 500 to 1,500, from 500 to 2,000, from 500 to 2,500, from 500 to 3,000, from 1,000 to 1,500, from 1,000 to 2,000, from 1,000 to 2,500, from 1,000 to 3,000, from 1,500 to 2,000, from 1,500 to 2,500, from 1,500 to 3,000, from 2,000 to 3,000, from 2,000 to 2,500, and from 2,500 to 3,000). In some instances, the poly A tail is designed relative to the length of the overall polynucleotide or the length of a particular region of the polynucleotide. This design can be based on the length of a coding region, the length of a particular feature or region or based on the length of the ultimate product expressed from the polynucleotides. In this context, the poly A tail can be 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% greater in length than the polynucleotide or feature thereof. The poly A tail can also be designed as a fraction of the polynucleotides to which it belongs. In this context, the poly A tail can be 10, 20, 30, 40, 50, 60, 70, 80, or 90% or more of the total length of the construct, a construct region or the total length of the construct minus the poly A tail. Further, engineered binding sites and conjugation of polynucleotides for Poly A binding protein can enhance expression. Additionally, multiple distinct polynucleotides can be linked together via the PABP (Poly A binding protein) through the 3′-end using modified nucleotides at the 3′- terminus of the poly A tail. Transfection experiments can be conducted in relevant cell lines at and protein production can be assayed by ELISA at 12hr, 24hr, 48hr, 72hr and day 7 post-transfection. In some instances, the polynucleotides of the present disclosure are designed to include a poly A-G Quartet region. The G-quartet is a cyclic hydrogen bonded array of four guanine nucleotides that can be formed by G-rich sequences in both DNA and RNA. In this instance, the G-quartet is incorporated at the end of the poly A tail. The resultant polynucleotide is assayed for stability, protein production and other parameters including Attorney Docket No.: 45817-0174WO1 half-life at various time points. It has been discovered that the poly A-G quartet results in protein production from an mRNA equivalent to at least 75% of that seen using a poly A tail of 120 nucleotides alone (SEQ ID NO:196). In some instances, the poly A tail comprises an alternative nucleoside, e.g., inverted thymidine. Poly A tails comprising an alternative nucleoside, e.g., inverted thymidine, may be generated as described herein. For instance, mRNA constructs may be modified by ligation to stabilize the poly A tail. Ligation may be performed using 0.5- 1.5 mg / mL mRNA (5′ Cap1, 3′ A100), 50 mM Tris-HCl pH 7.5, 10 mM MgCl2, 1 mM TCEP, 1000 units / mL T4 RNA Ligase 1, 1 mM ATP, 20% w / v polyethylene glycol 8000, and 5:1 molar ratio of modifying oligo to mRNA. Modifying oligo has a sequence of 5′- phosphate-AAAAAAAAAAAAAAAAAAAA-(inverted deoxythymidine (idT) (SEQ ID NO:209)) (see below). Ligation reactions are mixed and incubated at room temperature (~22°C) for, e.g., 4 hours. Stable tail mRNA are purified by, e.g., dT purification, reverse phase purification, hydroxyapatite purification, ultrafiltration into water, and sterile filtration. The resulting stable tail-containing mRNAs contain the following structure at the 3′end, starting with the poly A region: A100- UCUAGAAAAAAAAAAAAAAAAAAAA-inverted deoxythymidine (SEQ ID NO:211). Modifying oligo to stabilize tail (5′-phosphate-AAAAAAAAAAAAAAAAAAAA- (inverted deoxythymidine)(SEQ ID NO:209)):

[0004] Attorney Docket No.: 45817-0174WO1 In some instances, the poly A tail comprises A100-UCUAG-A20-inverted deoxy- thymidine (SEQ ID NO:211). In some instances, the poly A tail consists of A100- UCUAG-A20-inverted deoxy-thymidine (SEQ ID NO:211). Start codon region The disclosure also includes a polynucleotide that comprises both a start codon region and the polynucleotide described herein (e.g., a polynucleotide comprising a nucleotide sequence encoding a fusion protein described herein. In some cases, the polynucleotides of the present disclosure can have regions that are analogous to or function like a start codon region. In some cases, the translation of a polynucleotide can initiate on a codon that is not the start codon AUG. Translation of the polynucleotide can initiate on an alternative start codon such as, but not limited to, ACG, AGG, AAG, CTG / CUG, GTG / GUG, ATA / AUA, ATT / AUU, TTG / UUG (see Touriol et al. Biology of the Cell 95 (2003) 169- 178 and Matsuda and Mauro PLoS ONE, 20105:11; the contents of each of which are herein incorporated by reference in its entirety). As a non-limiting example, the translation of a polynucleotide begins on the alternative start codon ACG. As another non-limiting example, polynucleotide translation begins on the alternative start codon CTG or CUG. As yet another non-limiting example, the translation of a polynucleotide begins on the alternative start codon GTG or GUG. Nucleotides flanking a codon that initiates translation such as, but not limited to, a start codon or an alternative start codon, are known to affect the translation efficiency, the length and / or the structure of the polynucleotide. (See, e.g., Matsuda and Mauro PLoS ONE, 20105:11; the contents of which are herein incorporated by reference in its entirety). Masking any of the nucleotides flanking a codon that initiates translation can be used to alter the position of translation initiation, translation efficiency, length and / or structure of a polynucleotide. In some cases, a masking agent can be used near the start codon or alternative start codon in order to mask or hide the codon to reduce the probability of translation initiation at the Attorney Docket No.: 45817-0174WO1 masked start codon or alternative start codon. Non-limiting examples of masking agents include antisense locked nucleic acids (LNA) polynucleotides and exon-junction complexes (EJCs) (See, e.g., Matsuda and Mauro describing masking agents LNA polynucleotides and EJCs (PLoS ONE, 20105:11); the contents of which are herein incorporated by reference in its entirety). In another case, a masking agent can be used to mask a start codon of a polynucleotide in order to increase the likelihood that translation will initiate on an alternative start codon. In some cases, a masking agent can be used to mask a first start codon or alternative start codon in order to increase the chance that translation will initiate on a start codon or alternative start codon downstream to the masked start codon or alternative start codon. In some instances, a start codon or alternative start codon can be located within a perfect complement for a miRNA binding site. The perfect complement of a miRNA binding site can help control the translation, length and / or structure of the polynucleotide similar to a masking agent. As a non-limiting example, the start codon or alternative start codon can be located in the middle of a perfect complement for a miRNA binding site. The start codon or alternative start codon can be located after the first nucleotide, second nucleotide, third nucleotide, fourth nucleotide, fifth nucleotide, sixth nucleotide, seventh nucleotide, eighth nucleotide, ninth nucleotide, tenth nucleotide, eleventh nucleotide, twelfth nucleotide, thirteenth nucleotide, fourteenth nucleotide, fifteenth nucleotide, sixteenth nucleotide, seventeenth nucleotide, eighteenth nucleotide, nineteenth nucleotide, twentieth nucleotide or twenty-first nucleotide. In another instance, the start codon of a polynucleotide can be removed from the polynucleotide sequence in order to have the translation of the polynucleotide begin on a codon that is not the start codon. Translation of the polynucleotide can begin on the codon following the removed start codon or on a downstream start codon or an alternative start codon. In a non-limiting example, the start codon ATG or AUG is removed as the first 3 nucleotides of the polynucleotide sequence in order to have translation initiate on a downstream start codon or alternative start codon. The polynucleotide sequence where the start codon was removed can further comprise at least Attorney Docket No.: 45817-0174WO1 one masking agent for the downstream start codon and / or alternative start codons in order to control or attempt to control the initiation of translation, the length of the polynucleotide and / or the structure of the polynucleotide. Stop Codon Region The disclosure also includes a polynucleotide that comprises both a stop codon region and the polynucleotide described herein (e.g., a polynucleotide comprising a nucleotide sequence encoding a fusion protein described herein. In some cases, the polynucleotides of the disclosure can include at least two stop codons before the 3′ untranslated region (UTR). The stop codon can be selected from TGA, TAA and TAG in the case of DNA, or from UGA, UAA and UAG in the case of RNA. In some instances, the polynucleotides of the present disclosure include the stop codon TGA in the case or DNA, or the stop codon UGA in the case of RNA, and one additional stop codon. In a further instance, the addition stop codon can be TAA or UAA. In another case, the polynucleotides of the present disclosure include three consecutive stop codons, four stop codons, or more. Combination of mRNA elements Any of the polynucleotides disclosed herein can comprise one, two, three, or all of the following elements: (a) a 5′-UTR, e.g., as described herein; (b) a coding region comprising a stop element (e.g., as described herein); (c) a 3′-UTR (e.g., as described herein) and; optionally (d) a 3′ stabilizing region, e.g., as described herein. Also disclosed herein are LNP compositions comprising the same. In one instance, a polynucleotide of the disclosure comprises (a) a 5′ UTR described in Table 3 or a variant or fragment thereof and (b) a coding region comprising a stop element provided herein. In one case, the polynucleotide further comprises a cap structure, e.g., as described herein, or a poly A tail, e.g., as described herein. In one case, the polynucleotide further comprises a 3′ stabilizing region, e.g., as described herein. Attorney Docket No.: 45817-0174WO1 In another instance, a polynucleotide of the disclosure comprises (a) a 5′ UTR described in Table 3 or a variant or fragment thereof and (c) a 3′ UTR described in Table 4 or a variant or fragment thereof. In one case, the polynucleotide further comprises a cap structure, e.g., as described herein, or a poly A tail, e.g., as described herein. In another case, the polynucleotide further comprises a 3′ stabilizing region, e.g., as described herein. In another instance, a polynucleotide of the disclosure comprises (c) a 3′ UTR described in Table 4 or a variant or fragment thereof and (b) a coding region comprising a stop element provided herein. In one case, the polynucleotide comprises a sequence provided in Table 5. In another case, the polynucleotide further comprises a cap structure, e.g., as described herein, or a poly A tail, e.g., as described herein. In another case, the polynucleotide further comprises a 3′ stabilizing region, e.g., as described herein. In another instance, a polynucleotide of the disclosure comprises (a) a 5′ UTR described in Table 3 or a variant or fragment thereof; (b) a coding region comprising a stop element provided herein; and (c) a 3′ UTR described in Table 4 or a variant or fragment thereof. In one case, the polynucleotide further comprises a cap structure, e.g., as described herein, or a poly A tail, e.g., as described herein. In another case, the polynucleotide further comprises a 3′ stabilizing region, e.g., as described herein. In another instance, a polynucleotide of the disclosure comprises (a) a 5′ UTR described in Table 3 or a variant or fragment thereof, (b) a coding region comprising a stop element provided herein; and (c) a 3′ UTR comprising the sequence of SEQ ID NO:139. In one case, the polynucleotide further comprises a cap structure, e.g., as described herein, or a poly A tail, e.g., as described herein. In one instance, a polynucleotide of this disclosure comprises or consists of a sequence provided in any one of SEQ ID NOs.: 121-132 or 137-139 (see, Table 5). Table 5: Exemplary 3′ UTR and stop element sequences Attorney Docket No.: 45817-0174WO1 SEQ ID Sequence NO information Sequence C C C C C C C C C C C C C C C G A Attorney Docket No.: 45817-0174WO1 AAGUAGGAAACACUACAGUGGUCUUUGAAUAAAG UCUGAGUGGGCGGC C C A C C A C C G C U C C A C y p g g In certain instances, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding a fusion protein described herein, comprises from 5′ to 3′ end: (i) a 5′ cap such as provided above; (ii) a 5′ UTR, such as the sequences provided above; (iii) an ORF encoding a fusion protein described herein (e.g., SEQ ID NO:3, optionally including a different signal peptide than that present in SEQ ID NO:3), Attorney Docket No.: 45817-0174WO1 wherein the ORF has at least 90%, at least 95%, at least 97%, at least 98%, at least 99%, or 100% sequence identity to the sequence of SEQ ID NO:25; (iv) at least one stop codon; (v) a 3′ UTR, such as the sequences provided above; and (vi) a poly A tail provided above. In some instances, the polynucleotide further comprises a miRNA binding site, e.g., one or more (e.g., 1, 2, 3) miRNA binding sites that bind to miRNA-142 or miR- 122. In some cases, the 5′ UTR comprises the miRNA binding site. In some cases, the 3′ UTR comprises the miRNA binding site. In some instances, the 3’UTR and / or the poly A tail include an IDR sequence. In some instances, a polynucleotide of the present disclosure comprises a nucleotide sequence encoding a polypeptide sequence at least 70%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96% , at least 97%, at least 98%, at least 99%, or 100% identical to the protein sequence of a human MOG protein having the amino acid sequence of SEQ ID NO:35. In some instances, a polynucleotide of the present disclosure comprises a nucleotide sequence encoding a polypeptide sequence at least 70%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96% , at least 97%, at least 98%, at least 99%, or 100% identical to the protein sequence of a human MOG protein having the amino acid sequence of SEQ ID NO:34. In some instances, a polynucleotide of the present disclosure comprises a nucleotide sequence encoding a polypeptide sequence at least 70%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96% , at least 97%, at least 98%, at least 99%, or 100% Attorney Docket No.: 45817-0174WO1 identical to the protein sequence of a human MOG protein having the amino acid sequence of SEQ ID NO:33. In some instances, a polynucleotide of the present disclosure comprises a nucleotide sequence encoding a polypeptide sequence at least 70%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96% , at least 97%, at least 98%, at least 99%, or 100% identical to the protein sequence of a human MOG protein having the amino acid sequence of SEQ ID NO:3. In some instances, a polynucleotide of the present disclosure comprises a nucleotide sequence encoding a polypeptide sequence at least 70%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96% , at least 97%, at least 98%, at least 99%, or 100% identical to the protein sequence of a human MITD protein having the amino acid sequence of SEQ ID NO:29. In some instances, a polynucleotide of the present disclosure comprises a nucleotide sequence encoding a polypeptide sequence at least 70%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96% , at least 97%, at least 98%, at least 99%, or 100% identical to the protein sequence of a human LAMP1 protein having the amino acid sequence of SEQ ID NO:30 or 31. In some instances, a polynucleotide of the present disclosure comprises a nucleotide sequence encoding a polypeptide sequence at least 70%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96% , at least 97%, at least 98%, at least 99%, or 100% Attorney Docket No.: 45817-0174WO1 identical to the protein sequence of a CD74 protein having the amino acid sequence of SEQ ID NO:32. In some cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding a polypeptide, comprises (1) a 5′ cap such as provided above, for example, m7Gp-ppGm-A, (2) a 5′ UTR, (3) a nucleotide sequence ORF of at least 90% identity to the sequence of SEQ ID NO:25, (3) a stop codon, (4) a 3′UTR, and (5) a poly A tail provided above, for example, a poly A tail of SEQ ID NO:195 or A100-UCUAG-A20-inverted deoxy-thymidine (SEQ ID NO:211). In some cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding a polypeptide, comprises (1) a 5′ cap such as provided above, for example, m7Gp-ppGm-A, (2) a 5′ UTR, (3) a nucleotide sequence ORF of at least 95% identity to the sequence of SEQ ID NO:25, (3) a stop codon, (4) a 3′UTR, and (5) a poly A tail provided above, for example, a poly A tail of SEQ ID NO:195 or A100-UCUAG-A20-inverted deoxy-thymidine (SEQ ID NO:211). In some cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding a polypeptide, comprises (1) a 5′ cap such as provided above, for example, m7Gp-ppGm-A, (2) a 5′ UTR, (3) a nucleotide sequence ORF of SEQ ID NO:25, (3) a stop codon, (4) a 3′UTR, and (5) a poly A tail provided above, for example, a poly A tail of SEQ ID NO:195 or A100-UCUAG-A20-inverted deoxy-thymidine (SEQ ID NO:211). In certain instances, all uracils in the polynucleotide (e.g., mRNA) described herein are replaced by N1-methylpseudouracil. Exemplary MOG fusion nucleotide constructs are described below from 5’ to 3’. 5′ UTR of SEQ ID NO:15, ORF Sequence of SEQ ID NO:25, and 3′ UTR of SEQ ID NO:16; 5′ UTR of SEQ ID NO:15, ORF Sequence encoding n amino acid sequence comprising the sequence of SEQ ID NO:35 fused to a human LAMP1 (e.g., SEQ ID Attorney Docket No.: 45817-0174WO1 NO:30 or 31) , a human CD74 (e.g., SEQ ID NO:32), or a human MITD sequence (e.g., SEQ ID NO:29), and 3′ UTR of SEQ ID NO:16; 5′ UTR of SEQ ID NO:15, ORF Sequence encoding n amino acid sequence comprising he sequence of SEQ ID NO:34 fused to a human LAMP1 (e.g., SEQ ID NO:30 or 31) , a human CD74 (e.g., SEQ ID NO:32), or a human MITD sequence (e.g., SEQ ID NO:29), and 3′ UTR of SEQ ID NO:16; 5′ UTR of SEQ ID NO:15, ORF Sequence encoding an amino acid sequence comprising he sequence of SEQ ID NO:33 fused to a human LAMP1 (e.g., SEQ ID NO:30 or 31) , a human CD74 (e.g., SEQ ID NO:32), or a human MITD sequence (e.g., SEQ ID NO:29), and 3′ UTR of SEQ ID NO:16. In certain instances, in all of the above constructs, all uracils therein are replaced by N1-methylpseudouracil. In some cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding a fusion protein described herein, comprises (1) a 5′ cap such as provided above, for example, m7Gp- ppGm-A, (2) a nucleotide sequence encoding a fusion protein described herein and (3) a poly A tail provided above, for example, a poly A tail of ~100 residues, e.g., SEQ ID NO:195 or A100-UCUAG-A20-inverted deoxy-thymidine (SEQ ID NO:211). In certain cases, all uracils of the polynucleotide are replaced by N1-methylpseudouracil. In some cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding fusion protein described herein, comprises (1) a 5′ cap such as provided above, for example, m7Gp- ppGm-A, (2) a nucleotide sequence with a sequence that is at least 90% identical to SEQ ID NO:25, and (3) a poly A tail provided above, for example, a poly A tail of ~100 residues, e.g., SEQ ID NO:195 or A100-UCUAG-A20-inverted deoxy-thymidine (SEQ ID NO:211). In certain cases, all uracils of the polynucleotide are replaced by N1- methylpseudouracil. In some cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding fusion protein Attorney Docket No.: 45817-0174WO1 described herein, comprises (1) a 5′ cap such as provided above, for example, m7Gp- ppGm-A, (2) a nucleotide sequence with a sequence that is at least 95% identical to SEQ ID NO:25, and (3) a poly A tail provided above, for example, a poly A tail of ~100 residues, e.g., SEQ ID NO:195 or A100-UCUAG-A20-inverted deoxy-thymidine (SEQ ID NO:211). In certain cases, all uracils of the polynucleotide are replaced by N1- methylpseudouracil. In some cases, a polynucleotide of the present disclosure, for example a polynucleotide comprising an mRNA nucleotide sequence encoding fusion protein described herein, comprises (1) a 5′ cap such as provided above, for example, m7Gp- ppGm-A, (2) a nucleotide sequence with the sequence of SEQ ID NO:25, and (3) a poly A tail provided above, for example, a poly A tail of ~100 residues, e.g., SEQ ID NO:195 or A100-UCUAG-A20-inverted deoxy-thymidine (SEQ ID NO:211). In certain cases, all uracils of the polynucleotide are replaced by N1-methylpseudouracil. Methods of Making Polynucleotides The present disclosure also provides methods for making a polynucleotide of the disclosure (e.g., a polynucleotide comprising a nucleotide sequence encoding a fusion protein described herein) or a complement thereof. In some aspects, a polynucleotide (e.g., a RNA, e.g., an mRNA) disclosed herein, and encoding a fusion protein of the disclosure, can be constructed using in vitro transcription (IVT). In other aspects, a polynucleotide (e.g., a RNA, e.g., an mRNA) disclosed herein, and encoding a fusion protein of the disclosure, can be constructed by chemical synthesis using an oligonucleotide synthesizer. In other aspects, a polynucleotide (e.g., a RNA, e.g., an mRNA) disclosed herein, and encoding a fusion protein of the disclosure is made by using a host cell. In certain aspects, a polynucleotide (e.g., a RNA, e.g., an mRNA) disclosed herein, and encoding a fusion protein of the disclosure is made by one or more combination of the IVT, chemical synthesis, host cell expression, or any other methods known in the art. Attorney Docket No.: 45817-0174WO1 Naturally occurring nucleosides, non-naturally occurring nucleosides, or combinations thereof, can totally or partially naturally replace occurring nucleosides present in the candidate nucleotide sequence and can be incorporated into a sequence- optimized nucleotide sequence (e.g., a RNA, e.g., an mRNA) encoding a fusion protein of the disclosure. The resultant polynucleotides, e.g., mRNAs, can then be examined for their ability to produce protein and / or produce a therapeutic outcome. Pharmaceutical Compositions and Formulations The present disclosure provides pharmaceutical compositions and formulations that comprise any of the polynucleotides described above. In some cases, the composition or formulation further comprises a delivery agent. In some instances, the composition or formulation can contain a polynucleotide comprising a sequence optimized nucleic acid sequence disclosed herein which encodes a fusion protein described herein. In some cases, the composition or formulation can contain a polynucleotide (e.g., a RNA, e.g., an mRNA) comprising a polynucleotide (e.g., an ORF) having significant sequence identity to a sequence optimized nucleic acid sequence disclosed herein which encodes a fusion protein of the disclosure. In some cases, the polynucleotide further comprises a miRNA binding site, e.g., a miRNA binding site that binds miR-126, miR-142, miR-122, miR-144, miR-146, miR-150, miR-155, miR-16, miR-21, miR-223, miR-24, miR-27, or miR-26a. Pharmaceutical compositions or formulation can optionally comprise one or more additional active substances, e.g., therapeutically and / or prophylactically active substances. Pharmaceutical compositions or formulation can be sterile and / or pyrogen- free. General considerations in the formulation and / or manufacture of pharmaceutical agents can be found, for example, in Remington: The Science and Practice of Pharmacy 21sted., Lippincott Williams & Wilkins, 2005 (incorporated herein by reference in its entirety). In some cases, compositions are administered to humans, human patients or subjects. For the purposes of the present disclosure, the phrase "active ingredient" generally refers to polynucleotides to be delivered as described herein. Attorney Docket No.: 45817-0174WO1 Formulations and pharmaceutical compositions described herein can be prepared by any method known or hereafter developed in the art of pharmacology. In general, such preparatory methods include the step of associating the active ingredient with an excipient and / or one or more other accessory ingredients, and then, if necessary and / or desirable, dividing, shaping and / or packaging the product into a desired single- or multi- dose unit. A pharmaceutical composition or formulation in accordance with the present disclosure can be prepared, packaged, and / or sold in bulk, as a single unit dose, and / or as a plurality of single unit doses. As used herein, a "unit dose" refers to a discrete amount of the pharmaceutical composition comprising a predetermined amount of the active ingredient. The amount of the active ingredient is generally equal to the dosage of the active ingredient that would be administered to a subject and / or a convenient fraction of such a dosage such as, for example, one-half or one-third of such a dosage. Relative amounts of the active ingredient, the pharmaceutically acceptable excipient, and / or any additional ingredients in a pharmaceutical composition in accordance with the present disclosure can vary, depending upon the identity, size, and / or condition of the subject being treated and further depending upon the route by which the composition is to be administered. In some cases, the compositions and formulations described herein can contain at least one polynucleotide of the disclosure. As a non-limiting example, the composition or formulation can contain 1, 2, 3, 4 or 5 polynucleotides of the disclosure. In some cases, the compositions or formulations described herein can comprise more than one type of polynucleotide. In some cases, the composition or formulation can comprise a polynucleotide in linear and circular form. In another case, the composition or formulation can comprise a circular polynucleotide and an in vitro transcribed (IVT) polynucleotide. In yet another case, the composition or formulation can comprise an IVT polynucleotide, a chimeric polynucleotide and a circular polynucleotide. Although the descriptions of pharmaceutical compositions and formulations provided herein are principally directed to pharmaceutical compositions and formulations that are Attorney Docket No.: 45817-0174WO1 suitable for administration to humans, it will be understood by the skilled artisan that such compositions are generally suitable for administration to any other animal, e.g., to non-human animals, e.g. non-human mammals. Also provided are pharmaceutical formulations that comprise a polynucleotide described herein (e.g., a polynucleotide comprising a nucleotide sequence encoding a fusion protein of the disclosure). The polynucleotides described herein can be formulated using one or more excipients to: (1) increase stability; (2) increase cell transfection; (3) permit the sustained or delayed release (e.g., from a depot formulation of the polynucleotide); (4) alter the biodistribution (e.g., target the polynucleotide to specific tissues or cell types); (5) increase the translation of encoded protein in vivo; and / or (6) alter the release profile of encoded protein in vivo. In some cases, the pharmaceutical formulation further comprises a delivery agent. In some cases, the delivery agent comprises a sialic acid lipid (e.g., SA-V (e.g., Compound 1 or a salt thereof) or SA-VI (e.g., Compound 9 or a salt thereof)), an ionizable amino lipid, a structural lipid, a phospholipid, and a PEG lipid (e.g., PEG-DMG), e.g., with a mole ratio in the range of about (i) 40-50 mole ratio% ionizable amino lipid, optionally 45-50 mole ratio% ionizable amino lipid, for example, 45-46 mole ratio%, 46-47 mole ratio%, 47-48 mole ratio%, 48-49 mole ratio%, or 49-50 mole ratio% for example about 45 mole ratio%, 45.5 mole ratio%, 46 mole ratio%, 46.5 mole ratio%, 47 mole ratio%, 47.5 mole ratio%, 48 mole ratio%, 48.5 mole ratio%, 49 mole ratio%, or 49.5 mole ratio%; (ii) 30-45 mole ratio% sterol (e.g., cholesterol), optionally 35-42 mole ratio% sterol, for example, 30-31 mole ratio%, 31-32 mole ratio%, 32-33 mole ratio%, 33-34 mole ratio%, 35-35 mole ratio%, 35-36 mole ratio%, 36-37 mole ratio%, 37-38 mole ratio%, 38-39 mole ratio%, or 39-40 mole ratio%, or 40-42 mole ratio% sterol; (iii) 5-15 mole ratio% helper lipid (e.g., DSPC), optionally 10-15 mole ratio% helper lipid, for example, 5-6 mole ratio%, 6-7 mole ratio%, 7-8 mole ratio%, 8-9 mole ratio%, 9-10 mole ratio%, 10-11 mole ratio%, 11-12 mole ratio%, 12-13 mole ratio%, 13-14 mole ratio%, or 14-15 mole ratio% helper lipid; and (iv) 1-5% PEG lipid (e.g., PEG-DMG), optionally 1-5 mole ratio% PEG lipid, for example 1.5 to 2.5 mole ratio%, 1-2 mole ratio%, 2-3 mole ratio%, 3-4 mole ratio%, Attorney Docket No.: 45817-0174WO1 or 4-5 mole ratio% PEG lipid. In some cases, the delivery agent comprises Cholesterol, and DSPC. A pharmaceutically acceptable excipient, as used herein, includes, but are not limited to, any and all solvents, dispersion media, or other liquid vehicles, dispersion or suspension aids, diluents, granulating and / or dispersing agents, surface active agents, isotonic agents, thickening or emulsifying agents, preservatives, binders, lubricants or oil, coloring, sweetening or flavoring agents, stabilizers, antioxidants, antimicrobial or antifungal agents, osmolality adjusting agents, pH adjusting agents, buffers, chelants, cryoprotectants, and / or bulking agents, as suited to the particular dosage form desired. Various excipients for Formulating pharmaceutical compositions and techniques for preparing the composition are known in the art (see Remington: The Science and Practice of Pharmacy, 21st Edition, A. R. Gennaro (Lippincott, Williams & Wilkins, Baltimore, MD, 2006; incorporated herein by reference in its entirety). Exemplary diluents include, but are not limited to, calcium or sodium carbonate, calcium phosphate, calcium hydrogen phosphate, sodium phosphate, lactose, sucrose, cellulose, microcrystalline cellulose, kaolin, mannitol, sorbitol, etc., and / or combinations thereof. Exemplary surface active agents and / or emulsifiers include, but are not limited to, natural emulsifiers (e.g., acacia, agar, alginic acid, sodium alginate, tragacanth, chondrux, cholesterol, xanthan, pectin, gelatin, egg yolk, casein, wool fat, cholesterol, wax, and lecithin), sorbitan fatty acid esters (e.g., polyoxyethylene sorbitan monooleate [TWEEN®80], sorbitan monopalmitate [SPAN®40], glyceryl monooleate, polyoxyethylene esters, polyethylene glycol fatty acid esters (e.g., CREMOPHOR®), polyoxyethylene ethers (e.g., polyoxyethylene lauryl ether [BRIJ®30]), PLUORINC®F 68, POLOXAMER®188, etc. and / or combinations thereof. Exemplary binding agents include, but are not limited to, starch, gelatin, sugars (e.g., sucrose, glucose, dextrose, dextrin, molasses, lactose, lactitol, mannitol), amino acids (e.g., glycine), natural and synthetic gums (e.g., acacia, sodium alginate), ethylcellulose, hydroxyethylcellulose, hydroxypropyl methylcellulose, etc., and combinations thereof. Attorney Docket No.: 45817-0174WO1 Oxidation is a potential degradation pathway for mRNA, especially for liquid mRNA formulations. In order to prevent oxidation, antioxidants can be added to the formulations. Exemplary antioxidants include, but are not limited to, alpha tocopherol, ascorbic acid, ascorbyl palmitate, benzyl alcohol, butylated hydroxyanisole, m-cresol, methionine, butylated hydroxytoluene, monothioglycerol, sodium or potassium metabisulfite, propionic acid, propyl gallate, sodium ascorbate, etc., and combinations thereof. Exemplary chelating agents include, but are not limited to, ethylenediaminetetraacetic acid (EDTA), citric acid monohydrate, disodium edetate, fumaric acid, malic acid, phosphoric acid, sodium edetate, tartaric acid, trisodium edetate, etc., and combinations thereof. Exemplary antimicrobial or antifungal agents include, but are not limited to, benzalkonium chloride, benzethonium chloride, methyl paraben, ethyl paraben, propyl paraben, butyl paraben, benzoic acid, hydroxybenzoic acid, potassium or sodium benzoate, potassium or sodium sorbate, sodium propionate, sorbic acid, etc., and combinations thereof. Exemplary preservatives include, but are not limited to, vitamin A, vitamin C, vitamin E, beta-carotene, citric acid, ascorbic acid, butylated hydroxyanisol, ethylenediamine, sodium lauryl sulfate (SLS), sodium lauryl ether sulfate (SLES), etc., and combinations thereof. In some cases, the pH of polynucleotide solutions is maintained between pH 5 and pH 8 to improve stability. Exemplary buffers to control pH can include, but are not limited to sodium phosphate, sodium citrate, sodium succinate, histidine (or histidine-HCl), sodium malate, sodium carbonate, etc., and / or combinations thereof. Exemplary lubricating agents include, but are not limited to, magnesium stearate, calcium stearate, stearic acid, silica, talc, malt, hydrogenated vegetable oils, polyethylene glycol, sodium benzoate, sodium or magnesium lauryl sulfate, etc., and combinations thereof. Attorney Docket No.: 45817-0174WO1 The pharmaceutical composition or formulation described here can contain a cryoprotectant to stabilize a polynucleotide described herein during freezing. Exemplary cryoprotectants include, but are not limited to mannitol, sucrose, trehalose, lactose, glycerol, dextrose, etc., and combinations thereof. The pharmaceutical composition or formulation described here can contain a bulking agent in lyophilized polynucleotide formulations to yield a "pharmaceutically elegant" cake, stabilize the lyophilized polynucleotides during long term (e.g., 36 month) storage. Exemplary bulking agents of the present disclosure can include, but are not limited to sucrose, trehalose, mannitol, glycine, lactose, raffinose, and combinations thereof. In some cases, the pharmaceutical composition or formulation further comprises a delivery agent. The delivery agent of the present disclosure can include, without limitation, liposomes, lipid nanoparticles, lipidoids, polymers, lipoplexes, microvesicles, exosomes, peptides, proteins, cells transfected with polynucleotides, hyaluronidase, nanoparticle mimics, nanotubes, conjugates, and combinations thereof. Lipid Nanoparticles The present disclosure provides lipid nanoparticles and populations of lipid nanoparticles comprising an ionizable amino lipid, a phospholipid, a PEG lipid, and a structural lipid, and, in a preferred embodiment, a sialic acid lipid. Without wishing to be bound by theory, it is understood that when administered to subjects, the LNPs comprising sialic acid lipids may result in reduced cytokine secretion, reduced inflammatory responses, increased targeting to bone marrow resident HSPCs, differential targeting of myeloid subsets, and enhanced protein production in the liver, as compared to LNPs of different composition. Without wishing to be bound by theory, it is understood that LNPs comprising sialic acid lipids formulated with sialic acid lipid added in the lipid stock solution may generally be small in size. Attorney Docket No.: 45817-0174WO1 Without wishing to be bound by theory, it is understood that the more-anionic zeta potentials observed for LNPs comprising sialic acid lipids relative to LNPs that lack sialic acid lipids may be due to the presence of negatively charged sialic acid moieties on the surface. Without wishing to be bound by theory, it is understood that the LNPs comprising sialic acid lipids may effectuate lower Sca1 expression (e.g., no significant Sca1 expression) relative to the Sca1 expression effectuate by LNPs of different composition. In an aspect, the present disclosure provides a sialic acid lipid of Formula (SA-I): or a salt or ionized form thereof, wherein: M is *-O-C(=O)- or *-C(=O)-O-; wherein * indicates attachment to R; R is C13-20 alkyl or C13-20 alkenyl; M’ is *-O-C(=O)- or *-C(=O)-O-; wherein * indicates attachment to R’; R’ is C13-20 alkyl or C13-20 alkenyl; X+ is a pharmaceutically acceptable cation; n is 40-50; L is –(C3-8 alkylene)-T-* or –(C3-8 heteroalkylene)-T-*, wherein the C3-8 alkylene or C3-8 heteroalkylene is optionally substituted with one or more oxo; T is -CH2-, -O-, -S-, or -NH-;

[0005] Attorney Docket No.: 45817-0174WO1 , wherein indicates R1 is - NR1’’-C(=O)-R1’’’; R1’ is H or C1-6 alkyl; R1’’ is H or C1-6 alkyl; R1’’’ is C1-6 alkyl; and . acid lipid is of Formula (SA-II): or a salt or ionized form thereof. In some embodiments, the sialic acid lipid is of Formula (SA-II’):

[0006] Attorney Docket No.: 45817-0174WO1 or a or n some embodiments, the sialic acid lipid is of Formula (SA-II’’): or a salt or ionized form thereof. In some embodiments, the sialic acid lipid is of Formula (SA-III): or a salt or ionized form thereof. Attorney Docket No.: 45817-0174WO1 In some embodiments, the sialic acid lipid is of Formula (SA-IV): or a salt or ionized form thereof. In some embodiments, the sialic acid lipid is of Formula (SA-V): or a salt or ionized form thereof. In some embodiments, the sialic acid lipid is of Formula (SA-V-i):

[0007] Attorney Docket No.: 45817-0174WO1 or a salt or ionized form thereof. In some embodiments, the sialic acid lipid is of Formula (SA-V-ii): or a salt or ionized form thereof. In some embodiments, the sialic acid lipid is of Formula (SA-VI):

[0008] Attorney Docket No.: 45817-0174WO1 or a or In some embodiments, the sialic acid lipid is of Formula (SA-VI-i): In some embodiments, the sialic acid lipid is of Formula (SA-VI-ii): or a salt or ionized form thereof. In an aspect, the present disclosure provides a lipid comprising a diacylated propylene glycol moiety, a phosphate moiety, a PEG moiety, and a sialic acid moiety. Attorney Docket No.: 45817-0174WO1 Variables R and R’ In some embodiments, R is a C13-20 alkyl. In some embodiments, R is a C15-20 alkyl. In some embodiments, R is a C13-15 alkyl. In some embodiments, R is a C16-18 alkyl. In come embodiments, R is a C13 alkyl. In come embodiments, R is a C14 alkyl. In come embodiments, R is a C15 alkyl. In some embodiments, R is a C16 alkyl. In some embodiments, R is a C17 alkyl. In some embodiments, R is a C18 alkyl. In some embodiments, R is a C19 alkyl. In some embodiments, R is a C20 alkyl. In some embodiments, R’ is a C13-20 alkyl. In some embodiments, R’ is a C15-20 alkyl. In some embodiments, R’ is a C13-15 alkyl. In some embodiments, R’ is a C16-18 alkyl. In come embodiments, R’ is a C13 alkyl. In come embodiments, R’ is a C14 alkyl. In come embodiments, R’ is a C15 alkyl. In some embodiments, R’ is a C16 alkyl. In some embodiments, R’ is a C17 alkyl. In some embodiments, R’ is a C18 alkyl. In some embodiments, R’ is a C19 alkyl. In some embodiments, R’ is a C20 alkyl. In some embodiments, R is a C15-20 alkenyl. In some embodiments, R is a C13-15 alkenyl. In some embodiments, R is a C16-18 alkenyl. Attorney Docket No.: 45817-0174WO1 In come embodiments, R is a C15 alkenyl. In some embodiments, R is a C16 alkenyl. In some embodiments, R is a C17 alkenyl. In some embodiments, R is a C18 alkenyl. In some embodiments, R is a C19 alkenyl. In some embodiments, R is a C20 alkenyl. In some embodiments, R’ is a C15-20 alkenyl. In some embodiments, R’ is a C13-15 alkenyl. In some embodiments, R’ is a C16-18 alkenyl. In come embodiments, R’ is a C15 alkenyl. In some embodiments, R’ is a C16 alkenyl. In some embodiments, R’ is a C17 alkenyl. In some embodiments, R’ is a C18 alkenyl. In some embodiments, R’ is a C19 alkenyl. In some embodiments, R’ is a C20 alkenyl. Variables M, M’, X+, and n In some embodiments, n is 40 to 50. In some embodiments, n is 41-45. In some embodiments, n is 42-44. In some embodiments, n is 40. In some embodiments, n is 41 In some embodiments, n is 42. In some embodiments, n is 43. In some embodiments, n is 44. In some embodiments, n is 45 In some embodiments, n is 46. In some embodiments, n is 47. In some embodiments, n is 48. Attorney Docket No.: 45817-0174WO1 In some embodiments, n is 49. In some embodiments, n is 50. In some embodiments, M is *-O-C(=O)-, wherein * indicates attachment to R. In some embodiments, M is *-C(=O)-O-, wherein * indicates attachment to R. In some embodiments, M’ is *-O-C(=O)-, wherein * indicates attachment to R’. In some embodiments, M’ is *-C(=O)-O-; wherein * indicates attachment to R’. In some embodiments, X+ is a metal cation. In some embodiments, X+ is an alkali metal cation. In some embodiments X+ is a sodium cation. In some embodiments, X+ is a lithium cation. In some embodiments, X+ is a potassium cation. In some embodiments, X+ is an ammonium cation. Variable L and T In some embodiments, L comprises a C3-8 alkylene moiety. In some embodiments, L is –(C3-8 alkylene)-X’-*, wherein: * indicates attachment to -La; T is -CH2-, -O-, -S-, or -NR-, wherein R is H or C1-6 alkyl; and the C1-10 alkylene is optionally substituted with one or more oxo groups. In some embodiments, T is -CH2-. In some embodiments, T is -O-. In some embodiments, T is -S-. In some embodiments, T is -NH-. In some embodiments, the alkylene is linear. In some embodiments, the alkylene is branched. In some embodiments, L is –(C3-8 alkylene)-O-*. In some embodiments, L is –(C3-8 alkylene)-S-*. In some embodiments, L is –(C3-8 alkylene)-NH-*. Attorney Docket No.: 45817-0174WO1 In some embodiments, L comprises a C3-8 heteroalkylene moiety. In some embodiments, L is –(C3-8 heteroalkylene)-X’-*, wherein: * indicates attachment to -La; T is -CH2-, -O-, -S-, or -NR-, wherein R is H or C1-6 alkyl; and the C1-10 alkylene is optionally substituted with one or more oxo groups.. In some embodiments, the heteroalkylene is linear. In some embodiments, the heteroalkylene is branched. In some embodiments, L is –(C3-8 heteroalkylene)-O-*. In some embodiments, L is –(C3-8 heteroalkylene)-S-*. In some embodiments, L is –(C3-8 heteroalkylene)-NH-*. In some embodiments, L is , wherein indicates attachment to -La-Sa. In some embodiments, L , wherein indicates attachment to -La-Sa. In some embodiments, L , wherein indicates attachment to -La-Sa. In some embodiments, L , wherein indicates attachment to -La-Sa. In some embodiments, L , wherein indicates attachment to -La-Sa. In some embodiments, L , indicates attachment to -La-Sa. Attorney Docket No.: 45817-0174WO1 In some embodiments, L is , wherein indicates attachment to -La-Sa. Variable La In some embodiments, La is a lactosyl moiety is derived from lactose. In some embodiments, the lactosyl moiety is a derivative of lactose. For example, the present disclosure contemplates the use of lactose, lactosamine, or N-acetyl lactosamine. The present disclosure contemplates the use of lactosyl moieties wherein an atom from the L moiety, e.g, a heteroatom represented by X’, substitutes for a hydroxyl group in lactose. For example, the present disclosure contemplates the use of lactosyl moieties wherein the hydroxyl group at the anomeric position of lactose is replaced by a heteroatom from the L moiety. In some embodiments, the lactosyl moiety comprises lactose. In some embodiments, the lactosyl moiety comprises lactosamine. In some embodiments, the lactosyl moiety comprises N-acetyl lactosamine. In some embodiments, La , wherein indicates attachment to L and indicates attachment to -Sa.

[0009] Attorney Docket No.: 45817-0174WO1 In some , wherein indicates attachment to L and In some , wherein indicates attachment to L and In some , wherein indicates attachment to L and - In some , wherein indicates attachment to L indicates attachment to -Sa. Attorney Docket No.: 45817-0174WO1 In some , wherein indicates attachment to L and In some embodiments, La , wherein indicates attachment to L and indicates - In some , wherein indicates attachment to L and -

[0010] Attorney Docket No.: 45817-0174WO1 In some , wherein indicates attachment to L and In some , wherein indicates attachment to L and ,wherein indicates - In some , wherein indicates attachment to L indicates attachment to -Sa. Attorney Docket No.: 45817-0174WO1 Variable Sa In some embodiments, Sa is a sialic acid moiety comprising neuraminic acid. In some embodiments, the sialic acid comprises a derivative of neuraminic acid. In some embodiments, the sialic acid comprises N-glycolneuraminic acid. In some embodiments, the sialic acid comprises 2-keto-3-deoxynonic acid. In some embodiments, the sialic acid comprises N-acylated neuraminic acid. In some embodiments, Sa is Variable -La-Sa In some .

[0011] Attorney Docket No.: 45817-0174WO1 In some . In some . In some embodiments, . In some embodiments, . Attorney Docket No.: 45817-0174WO1 In some embodiments, . In some embodiments, . In some embodiments, . In some embodiments, .

[0012] Attorney Docket No.: 45817-0174WO1 . . . Exemplary Embodiments In some embodiments, the sialic acid lipid is any one of the compounds shown in Table SA-1.

[0013] 361 1461

[0014] 561

[0015] 661 H H O O 761

[0016] 861 1OW4710-71854:.oNtekcoDyenrott

[0017] A 961 Attorney Docket No.: 45817-0174P01 In some embodiments, the present disclosure provides a lipid nanoparticle comprising a sialic acid lipid, an ionizable amino lipid, and a structural lipid, wherein the sialic acid lipid is of Formula (SA-I). In some embodiments, a phospholipid useful or potentially useful in the present invention is an anionic phospholipid. In some embodiments, the population of lipid nanoparticles comprises between about 0.1 mole ratio% to about 5 mole ratio%, about 0.1 mole ratio% to about 4 mole ratio%, about 0.1 mole ratio% to about 3 mole ratio%, about 0.1 mole ratio% to about 2 mole ratio%, about 0.2 mole ratio% to about 2 mole ratio%, about 0.4 mole ratio% to about 1.5 mole ratio% of the sialic acid lipid, or about 0.4 mole ratio% to about 1 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises between about 0.1 mole ratio% to about 5 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises between about 0.1 mole ratio% to about 4 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises between about 0.1 mole ratio% to about 3 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises between about 0.1 mole ratio% to about 2 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises between about 0.2 mole ratio% to about 2 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises between about 0.4 mole ratio% to about 1.5 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises between about 0.4 mole ratio% to about 1 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises about 0.1 mole ratio%, about 0.2 mole ratio%, about 0.3 mole ratio%, about 0.4 mole ratio%, about 0.5 mole ratio%, about 0.6 mole ratio%, about 0.7 mole ratio%, about 0.8 mole ratio%, about 0.9 mole ratio%, about 1.0 mole ratio%, about 1.1 mole ratio%, about 1.2 mole Attorney Docket No.: 45817-0174WO1 ratio%, about 1.3 mole ratio%, about 1.4 mole ratio%, about 1.5 mole ratio%, about 1.6 mole ratio%, about 1.7 mole ratio%, about 1.8 mole ratio%, about 1.9 mole ratio%, or about 2.0 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises about 0.5 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises about 0.6 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises about 0.7 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises about 0.8 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises about 0.9 mole ratio% of the sialic acid lipid. In some embodiments, the population of lipid nanoparticles comprises about 1.0 mole ratio% of the sialic acid lipid. In some embodiments, the ionizable amino lipid is compound I-301, compound II-6, I-25, or I-18. In some embodiments, the ionizable amino lipid is compound I-301 or compound II-6. In some embodiments, the ionizable amino lipid is compound I-301. Compound I- 301 is a compound of the formula , In some embodiments, the ionizable amino lipid is compound II-6. Compound II- 6 is a compound of the formula , Attorney Docket No.: 45817-0174WO1 In some embodiments, the ionizable amino lipid is I-18. I-18 is a compound of the formula , In some embodiments, the population of lipid nanoparticles comprises about 30 mole ratio% to about 50 mole ratio%, about 30 mole ratio% to about 45 mole ratio%, about 30 mole ratio% to about 40 mole ratio%, about 35 mole ratio% to about 45 mole ratio%, or about 35 mole ratio% to about 40 mole ratio% of the ionizable amino lipid. In some embodiments, the population of lipid nanoparticles comprises about 30 mole ratio%, about 35 mole ratio%, about 40 mole ratio%, about 45 mole ratio%, or about 50 mole ratio% of the ionizable amino lipid. In some embodiments, the population of lipid nanoparticles comprises about 30 mole ratio% to about 50 mole ratio% of the ionizable amino lipid (e.g., compound I-301, compound I-18, or compound II-6). In some embodiments, the population of lipid nanoparticles comprises about 35 mole ratio% to about 45 mole ratio% of the ionizable amino lipid (e.g., compound I-301, compound I-18, or compound II-6). ). In certain cases, the population of lipid nanoparticles comprises about 45 mole ratio% to about 50 mole ratio% of the ionizable amino lipid (e.g., compound I-301, compound I-18, or compound II-6). In one instance, the population of lipid nanoparticles comprises about 47 mole ratio% of the ionizable amino lipid (e.g., compound I-301, compound I-18, or compound II-6). In some embodiments, the population of lipid nanoparticles comprises about 30 mole ratio% to about 50 mole ratio%, about 30 mole ratio% to about 45 mole ratio%, about 30 mole ratio% to about 40 mole ratio%, about 35 mole ratio% to about 45 mole ratio%, or about 35 mole ratio% to about 40 mole ratio% of compound 301. In some embodiments, the population of lipid nanoparticles comprises about 30 mole ratio%, Attorney Docket No.: 45817-0174WO1 about 35 mole ratio%, about 40 mole ratio%, about 45 mole ratio%, about 47 mole ratio%, or about 50 mole ratio% of compound I-301. In some embodiments, the population of lipid nanoparticles comprises about 30 mole ratio% to about 50 mole ratio%, about 30 mole ratio% to about 45 mole ratio%, about 30 mole ratio% to about 40 mole ratio%, about 35 mole ratio% to about 45 mole ratio%, or about 35 mole ratio% to about 40 mole ratio% of compound 301. In some embodiments, the population of lipid nanoparticles comprises about 30 mole ratio%, about 35 mole ratio%, about 40 mole ratio%, about 45 mole ratio%, about 47 mole ratio%, or about 50 mole ratio% of compound I-18. In one instance, the population of lipid nanoparticles comprises about 47 mole ratio% of I-18. In some embodiments, the population of lipid nanoparticles comprises about 30 mole ratio% to about 50 mole ratio%, about 30 mole ratio% to about 45 mole ratio%, about 30 mole ratio% to about 40 mole ratio%, about 35 mole ratio% to about 45 mole ratio%, or about 35 mole ratio% to about 40 mole ratio% of compound II-6. In some embodiments, the population of lipid nanoparticles comprises about 30 mole ratio%, about 35 mole ratio%, about 40 mole ratio%, about 45 mole ratio%, about 47 mole ratio%, or about 50 mole ratio% of compound II-6. In one instance, the population of lipid nanoparticles comprises about 47 mole ratio% of II-6. In some embodiments, the structural lipid is cholesterol. In some embodiments, the population of lipid nanoparticles comprises about 15 mole ratio% to about 50 mole ratio%, about 20 mole ratio% to about 50 mole ratio%, about 25 mole ratio% to about 50 mole ratio%, about 30 mole ratio% to about 50 mole ratio%, about 35 mole ratio% to about 50 mole ratio%, about 40 mole ratio% to about 50 mole ratio%, or about 45 mole ratio% to about 50 mole ratio% of the structural lipid (e.g., cholesterol). In some embodiments, the population of lipid nanoparticles comprises about 15 mole ratio% to about 45 mole ratio%, about 20 mole ratio% to about 45 mole ratio%, about 25 mole ratio% to about 45 mole ratio%, about 30 mole ratio% to about 45 mole ratio%, about 35 mole ratio% to about 45 mole ratio%, or about 40 mole ratio% to about Attorney Docket No.: 45817-0174WO1 45 mole ratio% of the structural lipid (e.g., cholesterol). In some embodiments the population of lipid nanoparticles comprises about 15 mole ratio% to about 40 mole ratio%, about 20 mole ratio% to about 40 mole ratio%, about 25 mole ratio% to about 40 mole ratio%, about 30 mole ratio% to about 40 mole ratio%, or about 35 mole ratio% to about 40 mole ratio% of the structural lipid (e.g., cholesterol). In some embodiments, the population of lipid nanoparticles comprises about 20 mole ratio% to about 45 mole ratio% of the structural lipid (e.g., cholesterol). In some embodiments, the population of lipid nanoparticles comprises about 20 mole ratio% to about 40 mole ratio% of the structural lipid (e.g., cholesterol). In some embodiments, the population of lipid nanoparticles comprises about 30 mole ratio% to about 40 mole ratio% of the structural lipid (e.g., cholesterol). In some embodiments, the population of lipid nanoparticles comp...

Claims

Attorney Docket No.: 45817-0174P01 WHAT IS CLAIMED IS:

1. A fusion polypeptide which induces tolerance in a human subject to a selected protein or proteins, wherein the fusion polypeptide comprises a first amino acid sequence which comprises at least one T cell epitope derived from the selected protein or proteins fused directly or via a linker to an endolysosomal targeting sequence, wherein the endolysosomal targeting sequence is not a sequence from human MITD, optionally wherein the fusion polypeptide comprises a signal sequence, and further optionally wherein the first amino acid sequence comprises a total of two to six, three to six, four to six, five, or six T cell epitopes derived from the selected protein or proteins.

2. The fusion polypeptide of claim 1, wherein the selected protein or proteins is an autoantigen, a foreign antigen, an allergen, a protein therapeutic, or a protein that the host immune system considers foreign during therapeutic replacement or transplantation, optionally wherein the fusion polypeptide comprises a single T cell epitope, a string of T cell epitopes, a shuffled T cell epitope, a subunit of, a partial sequence of, or a full antigen sequence of the selected protein, wherein the subunit or the partial antigen sequence comprises a T cell epitope, and further optionally wherein the first amino acid sequence comprises a string of T cell epitopes of the selected protein or proteins covalently linked in a sequence not present in the naturally occurring version of the selected protein or proteins, optionally wherein the string of T cell epitopes is linker by a linker comprising or consisting of the sequence of SEQ ID NO:

168.

3. The fusion polypeptide of claim 1, wherein the selected protein or proteins is human PDC-E2, human E3BP, human OGDC-E2, human BCOADC-E2, human PDC- E1a, human myelin oligodendrocyte glycoprotein (MOG), human gliadin, or human transglutaminase, optionally wherein the selected protein or proteins is human PDC-E2, human E3BP, human OGDC-E2, and / or human BCOADC-E2, and further optionally wherein the first amino acid sequence comprises a total of two to six, three to six, four toAttorney Docket No.: 45817-0174WO1 six, five, or six T cell epitopes derived from one or more of human PDC-E2, human E3BP, human OGDC-E2 and human BCOADC-E2 proteins, optionally wherein the first amino acid sequence comprises three T cell epitopes derived from human PDC-E2, and one T cell epitope each from each of human E3BP, human OGDC-E2 and human BCOADC-E2 proteins; and even further optionally wherein the first amino acid sequence comprises T cell epitope(s) derived from human PDC-E2 that are: (i) amino acids 425-444 (SEQ ID NO: 171); (ii) amino acids 163-176 (SEQ ID NO: 175); or (iii) amino acids 36-49 (SEQ ID NO: 173); human E3BP that is amino acids 34-47 (SEQ ID NO: 172); human BCOADC-E2 that is amino acids 90-103 (SEQ ID NO: 174); and human OGDC-E2 that is amino acids 100-113 (SEQ ID NO: 176), with 0, 1, 2, or 3 amino acid substitutions in one or more of the T cell epitopes compared to the naturally occurring amino acid sequence of the protein of interest, optionally wherein the T cell epitopes are linked via the linker comprising or consisting of the sequence of SEQ ID NO:168; and even further optionally wherein the first amino acid sequence comprises a sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO:169, optionally wherein the first amino acid sequence comprises or consists a signal peptide sequence with an amino acid sequence that is at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO:170, and wherein the signal peptide sequence is attached immediately upstream of the N-terminal amino acid residue of SEQ ID NO:169; and further optionally wherein the first amino acid sequence comprises a linker with the sequence of SEQ ID NO:168 attached immediately after the last C-terminal amino acid residue of SEQ ID NO:

169.

4. The fusion polypeptide of any one of claims 1 to 3, wherein the endolysosomal targeting sequence comprises a Y-X-X-φ sequence (wherein X is any amino acid and φ isAttorney Docket No.: 45817-0174WO1 any hydrophobic amino acid) from human LAMP1, human LAMP2, or human DC- LAMP, or a sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to amino acids 1-80 of human CD74 (invariant chain), optionally wherein the endolysosomal targeting sequence is: (i) a human LAMP1 polypeptide, optionally wherein the human LAMP1 polypeptide comprises or consists of an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO:30, or optionally wherein the human LAMP1 polypeptide comprises an amino acid sequence set forth in SEQ ID NO:31; or (ii) a human invariant chain (CD74) polypeptide, optionally wherein the human invariant chain polypeptide comprises or consists of an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence set forth in SEQ ID NO:

32.

5. The fusion polypeptide of any one of claims 1 to 4, wherein the first amino acid sequence is fused (i) directly; or (ii) via a linker to the endolysosomal targeting sequence, optionally wherein the linker is a Glycine Serine linker or comprises or consists of the sequence of SEQ ID NO:168, optionally wherein the endolysosomal targeting sequence is located at the C-terminus of the first amino acid sequence, unless the endolysosomal targeting sequence is CD74, in which case it is located at the N-terminus of the first amino acid sequence.

6. The fusion polypeptide of claim 1, comprising an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100%Attorney Docket No.: 45817-0174WO1 identical to the amino acid sequence set forth in SEQ ID NO:177, optionally wherein the fusion polypeptide comprises or consists a signal peptide sequence with an amino acid sequence that is at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of SEQ ID NO:170, and wherein the signal peptide sequence is attached immediately upstream of the N-terminal amino acid residue of SEQ ID NO:

177.

7. The fusion polypeptide of claim 1, comprising or consisting of an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence set forth in SEQ ID NO:

166.

8. The fusion polypeptide of any one of claims 1 to 7, further comprising a Treg epitope, optionally wherein the Treg epitope comprises an amino acid sequence that is at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to any one of the sequences of SEQ ID NOs: 213-220 or 43-48.

9. A combination comprising the fusion polypeptide of any one of claims 1 to 8 and one or more of: (i) an IL2 mutein comprising an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence set forth in SEQ ID NO:158 or SEQ ID NO:156; and / or (ii) an inhibitor of mTOR comprising an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence set forth in any one of SEQ ID NO:160, 162, or 164; and / or (iii) an activator of TGFβ comprising anAttorney Docket No.: 45817-0174WO1 amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence set forth in SEQ ID NO: 182 or 185.

10. A polynucleotide encoding the fusion polypeptide of any one of claims 1 to 8 or the polynucleotides encoding the combination of claim 9.

11. A vector or vectors comprising the polynucleotide or polynucleotides of claim 10.

12. A host cell comprising the polynucleotide or polynucleotides of claim 10 or the vector or vectors of claim 11.

13. A method of making a fusion polypeptide comprising culturing the host cell of claim 12 under conditions that promote the production of the fusion polypeptide and isolating the fusion polypeptide.

14. A polynucleotide comprising a messenger RNA (mRNA) comprising an open reading frame (ORF) encoding the fusion polypeptide of any one of claims 1 to 8, optionally wherein all the uracils in the mRNA or mRNAs or the ORF are N1- methylpseudouracils, and further optionally wherein the polynucleotide comprises a mRNA that encodes a Treg epitope.

15. The polynucleotide of claim 14, wherein the ORF comprises a nucleotide sequence that: (i) encodes an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the amino acid sequence set forth in any one of SEQ ID NOs: 169, 177, or 166; orAttorney Docket No.: 45817-0174WO1 (ii) is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the nucleic acid sequence set forth in SEQ ID NO: 165 or nucleotides 73-531 of SEQ ID NO:

165.

16. The polynucleotide of claim 14 or 15, further comprising one or more of: (i) a 5’ untranslated region (UTR) comprising or consisting of the nucleic acid sequence of SEQ ID NO:15 or SEQ ID NO:8; (ii) a 3’ UTR comprising or consisting of the nucleic acid sequence of SEQ ID NO:16, SEQ ID NO:9, or SEQ ID NO: 167; (iii) a 5’ terminal cap, optionally wherein the 5′ terminal cap comprises m7G-ppp- Gm, m7GpppG2^OMe, m7G-ppp-Gm-A, m7G-ppp-Gm-AG, Cap0, Cap1, ARCA, inosine, N1-methyl-guanosine, 2′-fluoro-guanosine, 7-deaza-guanosine, 8-oxo-guanosine, 2- amino-guanosine, LNA-guanosine, 2-azidoguanosine, Cap2, Cap4, 5′ methylG cap, or an analog thereof; and / or (iv) a poly A region, optionally wherein the poly A region is at least about 10, at least about 20, at least about 30, at least about 40, at least about 50, at least about 60, at least about 70, at least about 80, at least about 90 nucleotides in length, or at least about 100 nucleotides in length, and further optionally, wherein the poly A region is 100 nucleotides in length.

17. The polynucleotide of any one of claims 14 to 16, wherein all of the uracils of the mRNA are N1-methylpseudouracils or 5-methoxyuracils.

18. A combination comprising the polynucleotide of any one of claims 14 to 17, and an immunomodulatory agent wherein the immunomodulatory agent is a second polynucleotide, a protein, or a small molecule, optionally wherein the second polynucleotide comprises a second mRNA encoding an immunomodulatory agent,Attorney Docket No.: 45817-0174WO1 optionally wherein the immunomodulatory agent is an IL2 mutein, an activator of TGFβ such as ITB6 or ITB8, an inhibitor of mTOR such as MORG, PRAS40, or DEPTOR, an NFĸB inhibitor, or a PI3K / AKT inhibitor, further optionally wherein the second polynucleotide encodes: (i) an IL2 mutein, optionally wherein the IL2 mutein comprises an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence set forth in SEQ ID NO:158 or SEQ ID NO:156; (ii) an inhibitor of mTOR comprising an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence set forth in any one of SEQ ID NO:160, 161, or 164; or (iii) an activator of TGFβ comprising an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence set forth in SEQ ID NO: 181 or 184.

19. A polynucleotide comprising a messenger RNA (mRNA) comprising: [A] (i) a 5′ UTR, optionally comprising or consisting of the sequence of SEQ ID NO:15; (ii) an open reading frame (ORF) comprising a nucleotide sequence that encodes an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to any one of the sequences of SEQ ID NO:169, 177 or 166; (iii) a stop codon if not present at the C-terminal end of (ii) or at the N-terminus of 3’-UTR; and (iv) a 3′ UTR, optionally comprising or consisting of the sequence of SEQ ID NO:167, optionally wherein all of the uracils of the mRNA are N1-methylpseudouracils ; orAttorney Docket No.: 45817-0174WO1 [B] (i) a 5′ UTR, optionally comprising or consisting of the sequence of SEQ ID NO:15; (ii) an open reading frame (ORF) comprising a nucleotide sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the nucleic acid sequence of SEQ ID NO:165; (iii) a stop codon if not present at the C-terminal end of (ii) or at the N-terminus of 3’-UTR; and (iv) a 3′ UTR, optionally comprising or consisting of the sequence of SEQ ID NO:167, optionally wherein all of the uracils of the mRNA are N1-methylpseudouracils.

20. A combination comprising the polynucleotide of claim 19 and a second polynucleotide comprising a second mRNA comprising: (i) a 5′ UTR, optionally comprising or consisting of the sequence of SEQ ID NO:15; (ii) an open reading frame (ORF) comprising a nucleotide sequence that encodes an amino acid sequence that is at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or 100% identical to the sequence of any one of SEQ ID NOs:213- 220, 43-48, 156, 158, 160, 162, or 164; (iii) a stop codon if not present at the C-terminal end of (ii) or at the N-terminus of 3’-UTR; and (iv) a 3′ UTR, optionally comprising or consisting of the sequence of SEQ ID NO:167, optionally wherein all of the uracils of the mRNA are N1-methylpseudouracils.Attorney Docket No.: 45817-0174WO1 21. The polynucleotide of claim 19 or the combination of claim 20, wherein all uracils in the mRNA or mRNAs are N1-methylpseudouracils.

22. A pharmaceutical composition comprising the fusion polypeptide of any one of claims 1 to 8, the combination of any one of claims 9, 18, or 20, the polynucleotide of any one of claims 10, 14 to 17, or 19, or the polynucleotide or combination of claim 21, and a pharmaceutically acceptable excipient.

23. A delivery vehicle comprising the polynucleotide or combination of any one of claims 19 to 21, optionally wherein the delivery vehicle is a nanoparticle, and further optionally wherein the nanoparticle is a lipid nanoparticle, further optionally wherein the delivery vehicle is a lipid nanoparticle and wherein the lipid nanoparticle comprises an ionizable amino lipid, a structural lipid, a phospholipid, and a polyethylene glycol (PEG)- modified lipid, even further optionally wherein the ionizable amino lipid is present at 47 mole ratio %, the structural lipid is present at 39 mole ratio %, the phospholipid is present at 11 mole ratio % and the PEG-modified lipid is present at 3 mole ratio %, and yet further optionally wherein the lipid nanoparticle comprises a sialic acid lipid.

24. A composition comprising a lipid nanoparticle comprising a polynucleotide comprising a messenger RNA (mRNA) comprising: (i) a 5′ UTR consisting of the sequence of SEQ ID NO:15; (ii) an open reading frame (ORF) comprising a nucleotide sequence that encodes an amino acid sequence that is 100% identical to any one of the sequences of SEQ ID NO: 177 or 166; (iii) a stop codon if not present in (ii) or at the N-terminus of 3’-UTR; and (iv) a 3′ UTR consisting of the sequence of SEQ ID NO:167, wherein all of the uracils of the mRNA are N1-methylpseudouracils.Attorney Docket No.: 45817-0174WO1 25. The composition of claim 24, wherein the ORF comprises a nucleotide sequence that is 100% identical to the sequence of SEQ ID NO:165, wherein all of the uracils of the ORF are N1-methylpseudouracils.

26. A method of promoting tolerance to an antigen in a human subject, the method comprising administering to the human subject an effective amount of the fusion polypeptide of any one of claims 1 to 8, the polynucleotide of any one of claims 10, 14- 17, or 19, the combination of any one of claims 9, 18 or 20, the polynucleotide or combination of any one of claims 21, the delivery vehicle of claim 23, or the composition of claim 24 or 25, optionally wherein the administration is performed intravenously, subcutaneously, intramuscularly, intradermally, via inhalation, or via ingestion, and further optionally wherein the antigen is an autoantigen, a foreign antigen, an allergen, a protein therapeutic, or a protein that the host immune system considers foreign during therapeutic replacement or transplantation, and even further optionally wherein the antigen is one or more of PDC-E2, E3BP, OGDC-E2, and BCOADC-E2.

27. A method of promoting tolerance to an autoantigen associated with primary biliary cholangitis (PBC) in a human subject in need thereof, the method comprising administering to the subject an effective amount of a delivery vehicle of claim 23 or the composition of claim 24 or 25, optionally wherein administration is by IV bolus, further optionally wherein administration is by IV bolus rapid 10 minute infusion.

28. A method of treating PBC in a human subject in need thereof, the method comprising administering to the human subject an effective amount of a delivery vehicle of claim 23 or the composition of claim 24 or 25, optionally wherein the administration is performed intravenously, further optionally wherein administration is by IV bolus, and even optionally wherein administration is by IV bolus rapid 10 minute infusion.Attorney Docket No.: 45817-0174WO1 29. The method of any one of claims 26 to 28, wherein the effective amount is about 0.001 mg / kg or about 0.01 mg / kg, and further optionally wherein the effective amount is about 0.005 mg / kg to about 0.1 mg / kg.

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