Self-assembling protein nanostructures displaying paramyxovirus and / or pneumovirus F proteins and uses thereof

Abstract

Disclosed herein are nanostructures and uses thereof, comprising a plurality of first assemblies, each first assembly comprising a plurality of identical first polypeptides selected from I53_dn5A, I53_dn5A.1, and I53_dn5A.2, or variants thereof, and a plurality of second assemblies, each second assembly comprising a plurality of identical second polypeptides that are I53_dn5B or a variant thereof, wherein the plurality of first assemblies non-covalently interact with the plurality of second assemblies to form the nanostructure; and the nanostructure displays multiple copies of F protein or antigenic fragment thereof of one or more paramyxoviruses and / or pneumoviruses, respectively.

Description

[Technical Field]

[0001] cross reference This application claims priority to U.S. Provisional Patent Application No. 62 / 895,727, filed September 4, 2019, which is incorporated herein by reference in its entirety. [Background technology]

[0002] background Vaccination is a treatment modality used to prevent or reduce the severity of infections caused by a variety of infectious agents, including bacteria, viruses, and parasites. The development of new vaccines has important commercial and public health implications. In particular, improved vaccines against respiratory syncytial virus (RSV) are desirable.

[0003] Subunit vaccines are vaccines made from isolated antigens, usually proteins recombinantly expressed in bacterial, insect, or mammalian cell hosts. Typically, the antigenic components of subunit vaccines are selected from proteins of infectious pathogens that have been observed to induce innate immune responses during infection, although other components of infectious pathogens can also be used in some cases. Typical antigens for use in subunit vaccines include proteins expressed on the surface of target infectious pathogens, such as envelope glycoproteins expressed on the surface of viruses.

[0004] Subunit vaccines have various advantages, including: they do not contain live pathogens, thus eliminating the concern of patient infection by vaccines; they can be designed using standard genetic engineering techniques; they are more uniform than other forms of vaccines; and they can be produced in standardized recombinant protein expression production systems using well-characterized expression systems.In some cases, antigens can be genetically engineered to support the production of desired antibodies, such as neutralizing antibodies or broadly neutralizing antibodies.In particular, structural information about the antigen of interest obtained by X-ray crystallography, electron microscopy, or nuclear magnetic resonance experiments can be used to guide the rational design of subunit vaccines.

[0005] A known limitation of subunit vaccines is that the immune response they induce can sometimes be weaker than that induced by other types of vaccines, such as whole virus, live, or live-attenuated vaccines. The present inventors recognized that nanostructure-based vaccines have the potential to harness the advantages of subunit vaccines while increasing the potency and breadth of vaccine-induced immune responses through the multivalent presentation of symmetrically ordered antigens. Summary of the Invention

[0006] Summary of the Disclosure In one aspect, the present disclosure provides a method for producing a cellular membrane comprising: (a) a plurality of first assemblies, each first assembly comprising a plurality of identical first polypeptides, the first polypeptides being selected from SEQ ID NOs:2-4, in which the parenthesized residues are optional; a plurality of first assemblies comprising an amino acid sequence having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to an amino acid sequence selected from the group consisting of: TIFF0007818504000001.tif63134; and (b) a plurality of second assemblies, each second assembly comprising a plurality of identical second polypeptides, wherein the second polypeptides have the sequence of SEQ ID NO:1: a plurality of second assemblies comprising amino acid sequences having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of TIFF0007818504000002.tif9134; A nanostructure comprising: a plurality of first assemblies non-covalently interacting with a plurality of second assemblies to form a nanostructure; and the nanostructure displays multiple copies of one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof on the exterior surface of the nanostructure; A nanostructure is provided.

[0007] In one embodiment, the bolded and underlined residues in SEQ ID NOs: 1, 2, 3, and 4 are invariant in the first and second polypeptides. In another embodiment, the one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof comprise an amino acid sequence having at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to an amino acid sequence selected from the group consisting of SEQ ID NOs: 21-29 and 37. In another embodiment, the F protein or antigenic fragment thereof of one or more paramyxovirus and / or pneumovirus comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 21-24 and 37. The RSV F protein or variant thereof comprises an amino acid sequence having at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity, wherein the polypeptide comprises one or more of the following residues compared to the reference sequence: 67I, 149C, 458C, 46G, 465Q, 215P, 92D, and 487Q. In further embodiments, the one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof comprise an amino acid sequence having at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to an hMPV F protein or variant thereof comprising an amino acid sequence selected from the group consisting of SEQ ID NOs:25-29, wherein the polypeptide comprises one or more of the following residues compared to the reference sequence: 113C, 120C, 339C, 160F, 177L, 185P, and 426C.

[0008] In one embodiment, the F proteins or antigenic fragments thereof of one or more paramyxoviruses and / or pneumoviruses are expressed as fusion proteins with a first polypeptide and / or a second polypeptide. In another embodiment, each of the plurality of first assemblies comprises the same fusion protein, and / or each of the plurality of second assemblies comprises the same fusion protein. In another embodiment, the F proteins or antigenic fragments thereof of one or more paramyxoviruses and / or pneumoviruses are expressed as fusion proteins with a first polypeptide. In one embodiment, each of the plurality of first assemblies comprises the same fusion protein. In another embodiment, the plurality of first and / or second assemblies comprise F proteins or antigenic fragments thereof of a total of two or more paramyxoviruses and / or pneumoviruses expressed as fusion proteins with a first polypeptide and / or a second polypeptide. In one embodiment, only a subset of the first and / or second polypeptides comprises a fusion protein with an F protein or antigenic fragment thereof.

[0009] In another embodiment, each first assembly comprises a homotrimer of the first polypeptide. In a further embodiment, each second assembly comprises a homopentamer of the second polypeptide.

[0010] In one embodiment, the one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof comprise an amino acid sequence having at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence to the amino acid sequence of DS-Cav1 (SEQ ID NO:37). In another embodiment, each fusion protein comprises an amino acid linker disposed between the first polypeptide and the one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof and / or an amino acid linker disposed between the second polypeptide and the one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof. In one embodiment, the amino acid linker sequence comprises one or more trimerization domains. In another embodiment, the amino acid linker sequence comprises an amino acid sequence TIFF0007818504000003.tif4128, amino acid sequence a GCN4 coiled-coil domain, including but not limited to TIFF0007818504000004.tif4128, or a Gly-Ser linker, or TIFF0007818504000005.tif4129.

[0011] In one embodiment, the fusion protein comprises an amino acid sequence having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to an amino acid sequence selected from the group consisting of SEQ ID NOs: 5-11.

[0012] In another embodiment, the nanostructure comprises: (a) binds to a pre-fusion F-specific antibody, including but not limited to monoclonal antibody D25; (b) forming symmetrical structures, including but not limited to icosahedral structures; (c) is stable at 50°C; and / or (d) It is stable in 2.25 M guanidine hydrochloride.

[0013] The present disclosure also provides a nucleic acid encoding the fusion of any of the embodiments herein, an expression vector comprising the nucleic acid of the present disclosure, and a host cell comprising the nucleic acid or expression vector of the present disclosure.The present disclosure also provides an immunogenic composition comprising the nanostructure of the embodiments herein and a pharmaceutically acceptable carrier.In one embodiment, the immunogenic composition further comprises an adjuvant.

[0014] The present disclosure provides methods for generating an immune response to a paramyxovirus and / or pneumovirus F protein in a subject, as well as methods for treating or limiting paramyxovirus and / or pneumovirus infection in a subject, comprising administering to a subject in need thereof an effective amount of a nanostructure or immunogenic composition of any aspect herein to generate an immune response or treat or prevent paramyxovirus and / or pneumovirus infection in the subject.

[0015] Also provided herein is a method for in vitro assembly of nanostructures of any embodiment herein, comprising mixing two or more nanostructure components under aqueous conditions to drive spontaneous assembly of desired nanostructures. [The present invention 1001] (a) a plurality of first assemblies, each first assembly comprising a plurality of identical first polypeptides, the first polypeptides having the sequence of SEQ ID NOs:2-4: TIFF0007818504000006.tif63134 a plurality of first assemblies comprising amino acid sequences having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to an amino acid sequence selected from the group consisting of: (b) a plurality of second assemblies, each second assembly comprising a plurality of identical second polypeptides, the second polypeptides having the sequence of SEQ ID NO:1: TIFF0007818504000007.tif9134 a plurality of second assemblies comprising amino acid sequences having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of A nanostructure comprising: the plurality of first assemblies non-covalently interact with the plurality of second assemblies to form a nanostructure; and the nanostructure displays multiple copies of one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof on the outer surface of the nanostructure; The nanostructure. [The present invention 1002] 1001. The nanostructure of claim 1001, wherein the bolded and underlined residues in SEQ ID NOs: 1, 2, 3, and 4 are invariant in said first and second polypeptides. [The present invention 1003] The nanostructure of the present invention 1001 or 1002, wherein the F protein or antigenic fragment thereof of one or more paramyxoviruses and / or pneumoviruses comprises an amino acid sequence having at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to an amino acid sequence selected from the group consisting of SEQ ID NOs: 21 to 29 and 37. [The present invention 1004] The nanostructure of the present invention 1001 or 1002, wherein the F protein or antigenic fragment thereof of the one or more paramyxovirus and / or pneumovirus comprises an amino acid sequence selected from the group consisting of SEQ ID NOs: 21-24 and 37, and the RSV F protein or variant thereof comprises an amino acid sequence having at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity, wherein the polypeptide comprises one or more of the following residues compared to the reference sequence: 67I, 149C, 458C, 46G, 465Q, 215P, 92D, and 487Q. [The present invention 1005] 1001 or 1002. The nanostructure of claim 1001 or 1002, wherein the F protein or antigenic fragment thereof of one or more paramyxoviruses and / or pneumoviruses comprises an amino acid sequence having at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to a hMPV F protein or variant thereof comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 25-29, and wherein the polypeptide comprises one or more of the following residues compared to the reference sequence: 113C, 120C, 339C, 160F, 177L, 185P, and 426C. [The present invention 1006] The nanostructure of any of claims 1001 to 1005, wherein the F protein or antigenic fragment thereof of one or more paramyxoviruses and / or pneumoviruses is expressed as a fusion protein with the first polypeptide and / or the second polypeptide. [The present invention 1007] 1006. The nanostructure of claim 6, wherein each of said plurality of first assemblies comprises the same fusion protein, and / or each of said plurality of second assemblies comprises the same fusion protein. [The present invention 1008] The nanostructure of any of claims 1001 to 1005, wherein the F protein or antigen fragment thereof of said one or more types of paramyxovirus and / or pneumovirus is expressed as a fusion protein with said first polypeptide. [The present invention 1009] 1008. The nanostructure of claim 10, wherein each of the plurality of first assemblies comprises the same fusion protein. [The present invention 1010] A nanostructure of any of claims 1006 to 1009, wherein the plurality of first and / or second assemblies comprise F proteins or antigenic fragments thereof of a total of two or more types of paramyxovirus and / or pneumovirus expressed as fusion proteins with the first polypeptide and / or the second polypeptide. [The present invention 1011] The nanostructure of any one of 1006 to 1010, wherein only a subset of the first polypeptide and / or second polypeptide comprises a fusion protein with F protein or an antigen fragment thereof. [The present invention 1012] 1012. The nanostructure of any one of claims 1001 to 1011, wherein each first assembly comprises a homotrimer of said first polypeptide. [The present invention 1013] 1013. The nanostructure of any one of claims 1001 to 1012, wherein each second assembly comprises a homopentamer of said second polypeptide. [The present invention 1014] The nanostructure of any of claims 1001 to 1013, wherein the F protein or antigenic fragment thereof of one or more paramyxoviruses and / or pneumoviruses comprises an amino acid sequence having at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence similar to the amino acid sequence of DS-Cav1 (SEQ ID NO:37). [The present invention 1015] The nanostructure of any of claims 1006 to 1014, wherein each fusion protein comprises an amino acid linker arranged between the first polypeptide and the F protein or antigenic fragment thereof of the one or more paramyxoviruses and / or pneumoviruses, and / or an amino acid linker arranged between the second polypeptide and the F protein or antigenic fragment thereof of the one or more paramyxoviruses and / or pneumoviruses. [The present invention 1016] 1015. The nanostructure of the present invention, wherein the sequence of said amino acid linker comprises one or more trimerization domains. [The present invention 1017] The sequence of the amino acid linker is the amino acid sequence TIFF0007818504000008.tif4128 1015 or 1016 nanostructures of the present invention, comprising: [The present invention 1018] The sequence of the amino acid linker is the amino acid sequence TIFF0007818504000009.tif4128 The nanostructure of the present invention 1015 or 1016, comprising a GCN4 coiled-coil domain, including but not limited to: [The present invention 1019] the sequence of the amino acid linker is a Gly-Ser linker, or TIFF0007818504000010.tif4129 1015. The nanostructure of the present invention, comprising a linker selected from the group consisting of: [The present invention 1020] The nanostructure of any of claims 1006 to 1019, wherein the fusion protein comprises an amino acid sequence having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to an amino acid sequence selected from the group consisting of SEQ ID NOs: 5 to 11. [The present invention 1021] (a) binds to a pre-fusion F-specific antibody, including but not limited to monoclonal antibody D25; (b) forming symmetrical structures, including but not limited to icosahedral structures; (c) is stable at 50°C; and / or (d) stable in 2.25 M guanidine hydrochloride; The nanostructure of any one of 1001 to 1020 of the present invention. [The present invention 1022] A nucleic acid encoding a fusion protein according to any one of claims 1006 to 1019 of the present invention. [The present invention 1023] 1022. The nucleic acid of the present invention, wherein the fusion protein comprises an amino acid sequence having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to an amino acid sequence selected from the group consisting of SEQ ID NOs: 5-11. [The present invention 1024] An expression vector comprising the nucleic acid of the present invention 1022 or 1023 operably linked to a promoter. [The present invention 1025] A host cell comprising the nucleic acid or expression vector of any one of 1022 to 1024 of the present invention. [The present invention 1026] An immunogenic composition comprising any one of the nanostructures of the present inventions 1001 to 1021 and a pharmaceutically acceptable carrier. [The present invention 1027] The immunogenic composition of the present invention 1026 further comprising an adjuvant. [The present invention 1028] A method for generating an immune response in a subject against the F protein of a paramyxovirus and / or pneumovirus, the method comprising the step of administering to a subject in need thereof an effective amount of the nanostructure or immunogenic composition of any of the present inventions 1001 to 1021 and 1026 to 1027, thereby generating an immune response. [The present invention 1029] A method for treating or limiting paramyxovirus and / or pneumovirus infection in a subject, comprising administering to a subject in need thereof an effective amount of the nanostructure or immunogenic composition of any of the present inventions 1001 to 1021 and 1026 to 1027, thereby treating or preventing paramyxovirus and / or pneumovirus infection in the subject. [The present invention 1030] 1029. The method of claim 1028 or 1029, wherein said administering results in the production of paramyxovirus and / or pneumovirus neutralizing antibodies in said subject. [The present invention 1031] The neutralizing antibody has a titer of at least 1,000 (1 / ID 50 ) and is present in the serum of said subject. [The present invention 1032] A method for assembling in vitro the nanostructures of any of the present inventions 1001 to 1021, said method comprising mixing two or more nanostructure components under aqueous conditions to drive spontaneous assembly of the desired nanostructure. [The present invention 1033] The method of claim 1032, wherein the mixing step comprises mixing a first assembly comprising a first polypeptide (e.g., a trimeric first polypeptide) each comprising an F protein or an antigenic fragment thereof ("F protein"), and a suitable second assembly comprising a second polypeptide, in an approximately 1:1 molar ratio of first polypeptide:second polypeptide, under conditions and for a time suitable to allow interaction of the first assembly and the second assembly to form the nanostructure. [The present invention 1034] The method of claim 1033, wherein the mixing step comprises mixing a first assembly comprising a first polypeptide (e.g., a trimeric first polypeptide), in which less than all of the first polypeptide (e.g., 75%, 50%, 25%, etc.) comprises F protein, with a suitable second assembly comprising a second polypeptide, in a first polypeptide:second polypeptide molar ratio of approximately 1:1, under conditions and for a time suitable to allow the first assembly and the second assembly to interact to form the nanostructure. [This invention 1035] The method of claim 1033 or 1034, wherein the mixing step comprises mixing first assemblies comprising first polypeptides (e.g., trimeric first polypeptides) each comprising an F protein, wherein the first polypeptides collectively comprise a plurality of different F proteins (e.g., two, three, four, or more), with an appropriate second assembly comprising a second polypeptide, in a first polypeptide:second polypeptide molar ratio of approximately 1:1, under conditions and for a time suitable to allow the first assembly and the second assembly to interact to form the nanostructure comprising a plurality of F proteins or antigenic fragments thereof. [Brief explanation of the drawings]

[0016] [Figure 1] Schematic diagram of an exemplary embodiment of the RSV nanostructure vaccine of the present disclosure. The RSV F protein (hatched) is fused to the I53_dn5B nanostructure component (horizontal). In some embodiments, an intervening Foldon trimerization domain is included between the F protein and I53_dn5B (black solid). Linkers of different lengths are included between these domains (line). Cleavable N-terminal secretion signals and cleavable C-terminal purification tags are not shown. [Figure 2] 1 shows a graph of the expression levels of exemplary constructs RSV_F-dn5B_04 to RSV_F-dn5B_07 as determined by enzyme-linked immunoabsorbance assay (ELISA). [Figure 3] Graph showing biolayer interference of construct RSV_F-dn5B_07 (387) in the Octet® system using antibodies specific for RSV F protein epitopes: Pali, RSV F protein-specific antibody (pre-fusion and post-fusion); AM14, pre-fusion trimer conformation-specific antibody; 4D7, post-fusion conformation-specific antibody. [Figure 4A] This shows a graph of biolayer interference of RSV_F-dn5B_07 (387) compared to RSV_F-50A (309) in the Octet® system using D25, an antibody specific for the pre-fusion conformation of the RSV F protein. [Figure 4B] A bar graph of the fractional reactivity of each construct derived from the data shown in Figure 4B is shown. [Figure 5]Figure 1 shows a graph depicting dynamic light scattering measurements performed on RSV_F-dn5B_07 assembled into nanostructures with the companion component I53_dn5A. Data from three experimental runs are shown. The nanostructures have a hydrodynamic radius (Rh) of 23 nm and a polydispersity (Pd) of 17%. DETAILED DESCRIPTION OF THE INVENTION

[0017] Selected sequences of the present disclosure SEQ ID NO: 1 I53_dn5B SEQ ID NO: 2 I53_dn5A SEQ ID NO: 3 I53_dn5A.1 SEQ ID NO: 4 I53_dn5A.2 SEQ ID NO: 5 RSV_F-dn5B_01 SEQ ID NO: 6 RSV_F-dn5B_02 SEQ ID NO: 7 RSV_F-dn5B_03 SEQ ID NO: 8 RSV_F-dn5B_04 SEQ ID NO: 9 RSV_F-dn5B_05 SEQ ID NO: 10 RSV_F-dn5B_06 SEQ ID NO: 11 RSV_F-dn5B_07 SEQ ID NO: 37 DS-Cav1 SEQ ID NO: 38 Foldon trimerization tag

[0018] Detailed Description of the Disclosure All cited references are incorporated herein by reference in their entirety. In this application, unless otherwise specified, the techniques utilized are those described in Molecular Cloning: A Laboratory Manual (Sambrook, et al., 1989, Cold Spring Harbor Laboratory Press), Gene Expression Technology (Methods in Enzymology, Vol. 185, edited by D. Goeddel, 1991. Academic Press, San Diego, CA), "Guide to Protein Purification" in Methods in Enzymology (MP Deutschcer, ed., (1990) Academic Press, Inc.); PCR Protocols: A Guide to Methods and Applications (Innis, et al. 1990. Academic Press, San Diego, CA), Culture of Animal Cells: A Manual of Basic Technique, 2 nd (R.I. Freshney, Ed. 1987. Liss, Inc. New York, NY), Gene Transfer and Expression Protocols, pp. 109-128, ed. E.J. Murray, The Humana Press Inc., Clifton, NJ), and the Ambion 1998 Catalog (Ambion, Austin, TX).

[0019] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0020] As used herein, amino acid residues are abbreviated as follows: alanine (Ala; A), asparagine (Asn; N), aspartic acid (Asp; D), arginine (Arg; R), cysteine ​​(Cys; C), glutamic acid (Glu; E), glutamine (Gln; Q), glycine (Gly; G), histidine (His; H), isoleucine (Ile; I), leucine (Leu; L), lysine (Lys; K), methionine (Met; M), phenylalanine (Phe; F), proline (Pro; P), serine (Ser; S), threonine (Thr; T), tryptophan (Trp; W), tyrosine (Tyr; Y), and valine (Val; V).

[0021] As used herein, "about" means + / - 5% of the recited parameter.

[0022] All aspects of any aspect of this disclosure may be used in combination unless the context clearly indicates otherwise.

[0023] Unless the context clearly dictates otherwise, throughout the description and claims, words like "comprises," "comprising," and the like should be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; in other words, "including, but not limited to." Words using the singular or plural also include the plural and singular, respectively. Additionally, the words "herein," "above," and "below," and words of similar import, when used in this application, shall refer to this application as a whole and not to any particular portions of this application.

[0024] The description of the embodiments of the present disclosure is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. While specific embodiments of, and examples for, the present disclosure are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the present disclosure, as those skilled in the relevant art will recognize.

[0025] In a first aspect, the present disclosure provides a method for manufacturing a semiconductor device comprising: (a) a plurality of first assemblies, each first assembly comprising a plurality of identical first polypeptides, the first polypeptides being selected from SEQ ID NOs:2-4, in which the parenthesized residues are optional; a plurality of first assemblies comprising an amino acid sequence having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to an amino acid sequence selected from the group consisting of: TIFF0007818504000011.tif63134; and (b) a plurality of second assemblies, each second assembly comprising a plurality of identical second polypeptides, wherein the second polypeptides have the sequence of SEQ ID NO:1: a plurality of second assemblies comprising amino acid sequences having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of TIFF0007818504000012.tif14134; A nanostructure comprising: a plurality of first assemblies non-covalently interacting with a plurality of second assemblies to form a nanostructure; and the nanostructure displays multiple copies of one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof on the exterior surface of the nanostructure; A nanostructure is provided.

[0026] Disclosed herein are self-assembling polypeptide nanostructures that display paramyxovirus and / or pneumovirus F proteins in a multivalent manner on the nanostructure's exterior. Multiple copies of pairs of a first and a second polypeptide can self-assemble to form nanostructures, such as icosahedral nanostructures. The nanostructures contain symmetrically repeated, non-natural, non-covalent polypeptide-polypeptide interfaces that orient the first and second assemblies into nanostructures, such as nanostructures with icosahedral symmetry.

[0027] The nanostructures of the present disclosure are synthetic in that they do not exist in nature. The first and second polypeptides are non-naturally occurring proteins that can be produced by any suitable means, including recombinant production or chemical synthesis. Each member of the first polypeptides is identical to each other, and each member of the second polypeptides is identical to each other (however, if the first or second polypeptide is present as a fusion polypeptide with an F protein or antigenic fragment thereof of one or more paramyxoviruses and / or pneumoviruses, the F protein or antigenic fragment thereof may be different for each first or second polypeptide). The first protein and the second protein are different.

[0028] A plurality (two, three, four, five, six, or more) of first polypeptides self-assemble to form a first assembly, and a plurality (two, three, four, five, six, or more) of second polypeptides self-assemble to form a second assembly, and then a plurality of these first and second assemblies self-assemble non-covalently through a designed interface to produce a nanostructure.

[0029] The number of first polypeptides in the first assembly can be the same as or different from the number of second polypeptides in the second assembly, hi one exemplary embodiment, the first assembly comprises trimers of the first polypeptide and the second assembly comprises pentamers of the second polypeptide.

[0030] The first and second polypeptides can be of any suitable length for a given purpose of the resulting nanostructure.

[0031] The isolated polypeptides of SEQ ID NOs: 1 and 2-4 have the ability to self-assemble in pairs to form nanostructures (e.g., icosahedral nanostructures). Designing such pairs involves designing appropriate interface residues of each member of the polypeptide pair that can assemble to form the nanostructure. The nanostructures so formed contain a symmetrically repeated, non-natural, non-covalent polypeptide-polypeptide interface that orients the first and second assemblies into a nanostructure, such as a nanostructure with icosahedral symmetry.

[0032] Like proteins in general, polypeptides are expected to tolerate some variation in their designed sequences without disrupting their subsequent assembly into nanostructures, particularly when such variations involve conservative amino acid substitutions. As used herein, "conservative amino acid substitution" means that hydrophobic amino acids (Ala, Cys, Gly, Pro, Met, See, Sme, Val, Ile, Leu) can only be substituted with other hydrophobic amino acids; hydrophobic amino acids with bulky side chains (Phe, Tyr, Trp) can only be substituted with other hydrophobic amino acids with bulky side chains; amino acids with positively charged side chains (Arg, His, Lys) can only be substituted with other amino acids with positively charged side chains; amino acids with negatively charged side chains (Asp, Glu) can only be substituted with other amino acids with negatively charged side chains; and amino acids with polar, uncharged side chains (Ser, Thr, Asn, Gln) can only be substituted with other amino acids with polar, uncharged side chains.

[0033] In one embodiment, all of the oligomerization positions in bold and underlined font in SEQ ID NOs: 1-4 are invariant in the first and second polypeptides.

[0034] In one embodiment, one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof are expressed as a fusion protein with the first and / or second polypeptide. In these embodiments, one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof are preferably present at the N-terminus of the fusion protein, which configuration can always facilitate the presentation of one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof on the outer surface of the nanostructure. This preference for the presence of paramyxovirus and / or pneumovirus F proteins at the N-terminus of the fusion protein derives from the location of the C-terminus of the paramyxovirus and / or pneumovirus F proteins at one end ("bottom") of the F protein trimer; by positioning the gene fusion at this point, the majority of the F protein structure is presented and accessible on the outer surface of the nanostructure. In a further embodiment, the nanostructure comprises one or more copies of a fusion protein comprising at least two domains—a paramyxovirus and / or pneumovirus F protein or antigenic fragment thereof and a trimeric assembly domain (i.e., each first assembly is a homotrimer of the first polypeptide), and one or more copies of a second oligomer block (i.e., each second assembly is an oligomer of two or more copies of the second polypeptide). In another embodiment, the first and / or second polypeptide can be modified to allow one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof to be covalently linked to the first and / or second polypeptide. In one non-limiting example, the first and / or second polypeptide can be modified, such as by introducing various cysteine ​​residues at defined positions, to facilitate attachment of one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof.

[0035] In other embodiments, the one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof are attached to the first or second polypeptide by any suitable technique, including, but not limited to, covalent chemical cross-linking (by any suitable cross-linking technique) and non-covalent linkages, including engineered electrostatic interactions.

[0036] Trimer Assembly Domain In one embodiment of a trimeric assembly comprising a trimeric paramyxovirus and / or pneumovirus F protein or antigenic fragment thereof, the paramyxovirus and / or pneumovirus F protein or antigenic fragment thereof is genetically fused to a first polypeptide that self-assembles into a trimeric assembly. The trimeric assembly comprises a protein-protein interface that induces three copies of the first polypeptide to self-assemble to form a trimeric building block. Each copy of the first polypeptide further comprises a surface-exposed interface that interacts with a complementary surface-exposed interface on the second assembly domain. The complementary protein-protein interface between the trimeric assembly domain and the second assembly domain drives the assembly of multiple copies of the trimeric assembly domain and the second assembly domain into a target nanostructure. In some embodiments, each copy of the trimeric assembly domain of the nanostructure comprises a paramyxovirus and / or pneumovirus F protein or antigenic fragment thereof as a genetic fusion; these nanostructures display the F protein at maximum valency. In other embodiments, the nanostructures of the present disclosure comprise one or more copies of a trimer assembly domain having a paramyxovirus and / or pneumovirus F protein or antigenic fragment thereof as a genetic fusion, and one or more trimer assembly domains without the F protein as a genetic fusion; these nanostructures display the F protein in a partial valency. The trimer assembly domain can be any polypeptide sequence that interacts with a second assembly domain to form trimers and drive assembly into a target nanostructure.

[0037] The nanostructures of the present disclosure display multiple copies (i.e., two, three, or more) of the F protein or antigenic fragment thereof of one or more paramyxoviruses and / or pneumoviruses on their exterior surface. Exemplary paramyxoviruses and / or pneumoviruses include, but are not limited to, respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) (CL Afonso et al., Taxonomy of the order Mononegavirales: update 2016. Arch. Virol. 161, 2351-2360 (2016)).

[0038] As used herein, "on the exterior surface of the nanostructure" means that the F protein or antigenic fragment of one or more paramyxoviruses and / or pneumoviruses is accessible for binding by a B cell receptor, antibody, or antibody fragment and is not buried within the nanostructure.

[0039] The one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof can comprise any suitable native F protein, post-fusion antigen, or pre-fusion (pre-F) antigen, or variant thereof, capable of inducing an immune response that generates antibodies that bind to the paramyxovirus and / or pneumovirus F proteins. The nanostructure may display more than one F protein; thus, in some embodiments, the one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof comprise one, two, three, four, or more F proteins or antigenic fragments thereof. In one embodiment, the one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof can be as defined in Patent Publication No. US 2016 / 0046675 A1. In some embodiments, the one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof are selected from the group consisting of SEQ ID NOs: 1-350, 370-382, 389-693, 698-1026, 1429-1442, 1456-1468, and 1474-1478, as disclosed in U.S. Patent Application Publication No. 2016 / 0046675. In other embodiments, the F protein or antigenic fragment of one or more paramyxovirus and / or pneumovirus is selected from the group consisting of WO2012158613, US20160102123, US20140141037, WO2014079842, WO2014160463, US20140271699, EP2970393, WO2014174018, US20140271699, US20160176932, US20160122398, WO2017040387, WO2017109629, WO2017172890, WO2017207477, Krarup et al. (2015) Nature Communications 6:8143, and WO2017070387.

[0040] In certain embodiments, the F protein or antigenic fragment thereof of one or more paramyxoviruses and / or pneumoviruses comprises an amino acid sequence having at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the amino acid sequence of DS-Cav1 shown below (in each case, the protein may further comprise a suitable secretory signal—optionally a cleavable secretory signal, e.g., a cleavable secretory signal) at the N-terminus of the sequence disclosed herein. TIFF0007818504000013.tif4128). DS-Cav1 contains a prefusion-stabilized form of the fusion (F) glycoprotein, which induces improved protective responses against respiratory syncytial virus (RSV) in mice and macaques compared to postfusion RSV F (McLellan et al. (2013) Science 342:592-8).

[0041] DS-Cav1 (SEQ ID NO:37) (residues in brackets are optional) TIFF0007818504000014.tif45145

[0042] In other embodiments, the F protein comprises an amino acid sequence having at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to an amino acid sequence selected from the group consisting of SEQ ID NOs: 21-22.

[0043] TIFF0007818504000015.tif102146

[0044] SEQ ID NOs: 21-22 represent second-generation stabilized DS-Cav1 immunogens; mutations to DS-Cav1 are described, and it should be noted that the present disclosure contemplates the use of DS-Cav1 variants that differ by a single one of the described amino acid substitutions in SEQ ID NOs: 21 or 22 above, or by two or more of the described amino acid substitutions. In other embodiments, the F protein may comprise one or more of the following, each of which may further comprise one, two, or more of the described amino acid substitutions in SEQ ID NOs: 21 or 22 above: TIFF0007818504000016.tif45146TIFF0007818504000017.tif45145TIFF0007818504000018.tif201148TIFF0007818504000019.tif45145

[0045] In other embodiments, the F protein or antigenic fragment thereof of one or more paramyxovirus and / or pneumovirus may comprise an amino acid sequence having at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to the RSV F protein or variant thereof comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 21-24 and 37, wherein the polypeptide comprises one or more of the following residues compared to the reference sequence: 67I, 149C, 458C, 46G, 465Q, 215P, 92D, and 487Q.

[0046] In other embodiments, the one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof can comprise an amino acid sequence having at least 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to an MPV F protein or variant thereof comprising an amino acid sequence selected from the group consisting of SEQ ID NOs: 25-29, wherein the polypeptide comprises one or more of the following residues compared to the reference sequence: 113C, 120C, 339C, 160F, 177L, 185P, and 426C.

[0047] Linker and geometric requirements between the F protein and the trimer assembly domain In the nanostructures of the present disclosure, the F protein and the trimer assembly domain can be genetically fused so that they are both present in a single polypeptide. Preferably, the link between the F protein and the trimer assembly domain allows the F protein, or its antigenic fragment, to be displayed on the external surface of the nanostructures of the present disclosure. Therefore, the point of attachment to the trimer assembly domain should be on the external surface of the nanostructure formed by the trimer assembly domain and the second assembly domain in the absence of any F protein. As will be understood by those skilled in the art, a wide variety of polypeptide sequences can be used to link the paramyxovirus and / or pneumovirus F protein, or its antigenic fragment, to the trimer assembly domain. These polypeptide sequences are referred to as linkers. Any suitable linker can be used; there is no requirement for the amino acid sequence to function as a suitable linker. Beyond allowing the F protein, or its antigenic fragment, to be displayed on the external surface of the nanostructures of the present disclosure, there is no requirement that the linker impose a rigid relative orientation of the F protein, or its antigenic fragment, to the trimer assembly domain. In some embodiments, the linker contains an additional trimerization domain (eg, the foldon domain of T4 fibritin or the GCN4 coiled-coiled domain) that helps stabilize the trimeric form of the F protein. T4 fibritin foldon domain (optional in the linker region) (SEQ ID NO:38) TIFF0007818504000020.tif4128GCN4 Coiled-Coiled Domain (Optional in Linker Region) (SEQ ID NO: 19) TIFF0007818504000021.tif3128

[0048] In other embodiments, the linker can comprise a Gly-Ser linker of any suitable length (i.e., a linker consisting of glycine and serine residues). In various embodiments, the Gly-Ser linker can be 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, or more amino acids in length. In various embodiments, the Gly-Ser linker It may comprise or consist of the amino acid sequence of TIFF0007818504000022.tif18143.

[0049] Thus, in various non-limiting embodiments in which the F protein is present as a fusion protein with a first polypeptide and a linker is used, the F protein-linker sequence can include the following (exemplified in these non-limiting embodiments by DS-Cav1 as the F protein): The residues in parentheses are optional. The protein can optionally contain the amino acid sequence DS-Cav1 as an N-terminal DS-Cav1 signal peptide (not shown), which is cleaved during processing. It can be expressed with TIFF0007818504000023.tif4128: TIFF0007818504000024.tif52145

[0050] In various further embodiments, the first polypeptide comprises or consists of a fusion polypeptide of the first polypeptide fused to an F protein, wherein the fusion protein comprises an amino acid sequence having at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% sequence identity to an amino acid sequence selected from the group consisting of SEQ ID NOs: 5-11 (any residues in parentheses). Italics: Ds-Cav1 Residues in brackets are optional Underlined: T4 fibritin foldon domain Bold font: I53_dn5B * TIFF0007818504000025.tif116146TIFF0007818504000026.tif225146TIFF0007818504000027.tif7146

[0051] Second Assembly The nanostructures of the present disclosure can include multiple copies of a trimer first assembly and multiple copies of a second assembly. The second assembly includes a protein-protein interface that induces multiple copies of the second polypeptide to self-assemble to form the second assembly. Multiple oligomeric states of the second assembly, including dimers (2 copies), trimers (3 copies), tetramers (4 copies), pentamers (5 copies), hexamers (6 copies), or more, can be compatible with nanostructure formation. Each copy of the second assembly further includes a surface-exposed interface that interacts with a complementary surface-exposed interface on the trimer assembly domain. The complementary interface between the trimer assembly domain and the second assembly domain drives the assembly of multiple copies of the trimer assembly domain and the second assembly domain into a target nanostructure.

[0052] Assembly of nanostructures with maximum valence by in vitro assembly of two components In some embodiments, each trimeric first assembly of nanostructures has the same F protein as a genetic fusion; these nanostructures display the F protein at full (100%) valency. Such nanostructures are generated from purified first and second polypeptides in a process referred to as in vitro assembly. The purified trimeric first polypeptide containing the F protein is mixed with an appropriate second polypeptide in an approximately 1:1 molar ratio under aqueous conditions. The second assembly interacts with the trimeric first assembly to drive the assembly of the target nanostructure. Successful assembly of the target nanostructure can be confirmed by analyzing the in vitro assembly reaction using common biological or biophysical methods used to evaluate the physical size of proteins or protein assemblies, including, but not limited to, size exclusion chromatography, native gel electrophoresis, dynamic light scattering, multi-angle light scattering, analytical ultracentrifugation, negative stain electron microscopy, cryo-electron microscopy, or X-ray crystallography. If necessary, the assembled nanostructures can be purified from other species or molecules present in the in vitro assembly reaction using preparative techniques commonly used to isolate proteins by their physical size, including, but not limited to, size-exclusion chromatography, preparative ultracentrifugation, tangential flow filtration, or preparative gel electrophoresis. The presence of F protein in the nanostructures can be assessed by techniques commonly used to determine the identity of protein molecules in aqueous solution, including, but not limited to, SDS-PAGE, mass spectrometry, protein sequencing, or amino acid analysis. The accessibility of F protein on the outer surface of the particle and its conformation or antigenicity can be assessed by techniques commonly used to detect the presence and conformation of antigens, including, but not limited to, binding with monoclonal antibodies, conformation-specific monoclonal antibodies, or antigen-specific antisera.

[0053] In vitro assembly of partially valent nanostructures In other embodiments, the nanostructures of the present disclosure comprise one or more copies of a trimeric first assembly having an F protein as a genetic fusion and one or more trimeric first assemblies not having an F protein as a genetic fusion; these nanostructures display F protein with partial valency. These partial valency nanostructures are generated by in vitro assembly using a mixture of first polypeptides in which the proportion of trimeric first assemblies having an F protein as a genetic fusion equals the desired valency of the antigen in the resulting nanostructure. The in vitro assembly reaction typically contains an approximately 1:1 molar ratio of the entire first polypeptide to the entire second polypeptide. As a non-limiting example, performing an in vitro assembly reaction using a mixture of trimeric assemblies in which half of the first polypeptides have an F protein as a genetic fusion results in an assembled nanostructure with 50% F protein valency. That is, 50% of the available sites for F protein display on the nanostructure will be occupied. As a non-limiting example, if a nanostructure is an assembly of 120 subunits with icosahedral symmetry, the nanostructure will contain a total of 20 trimer building blocks, and a nanostructure with 50% valency will display 10 of the 20 possible F protein trimers. In this way, the ratio of a first polypeptide with F protein to a first polypeptide lacking F protein in an in vitro assembly reaction can be used to precisely tailor the valency of the F protein in the resulting nanostructure. It will be understood by those skilled in the art that this method can be tailored to the average valency; the valency of individual nanostructures in the mixture will be centered around the average. The success of assembly of such partially valenced nanostructures can be assessed using the techniques described above for determining fully valenced nanostructures, and, if necessary, the partially valenced nanostructures can be purified using the methods described for purifying fully valenced nanostructures. The average valency of the first polypeptide with F protein in a given sample can be assessed by quantitative analysis using the techniques described above for determining the presence of F protein in fully valenced nanostructures.

[0054] In vitro assembly of nanostructures that simultaneously display multiple F proteins In other embodiments, the disclosed nanostructures comprise two or more distinct first polypeptides genetically fused to an F protein; these nanostructures simultaneously display multiple distinct F proteins on the same nanostructure. These multi-antigen nanostructures are generated by in vitro assembly using a mixture of first polypeptides, each of which genetically fused to one of two or more distinct F proteins. The ratio of each first polypeptide in the mixture determines the average valency of each F protein in the resulting nanostructure. In vitro assembly reactions typically contain approximately a 1:1 molar ratio of total trimeric first polypeptide to total second polypeptide. The presence and average valency of each first polypeptide bearing an F protein in a given sample can be assessed by quantitative analysis using the techniques described above to determine the presence of F protein in nanostructures with maximum valency.

[0055] In various embodiments, the nanostructures have diameters of about 20 nanometers (nm) to about 40 nm, interior lumens with lateral widths of about 15 nm to about 32 nm, and protein shell pores with diameters of about 1 nm to about 14 nm in their longest dimension.

[0056] In one embodiment, the nanostructure has icosahedral symmetry. In this embodiment, the nanostructure can include 60 copies of a first polypeptide and 60 copies of a second polypeptide. In one such embodiment, the number of identical first polypeptides in each first assembly is different from the number of identical second polypeptides in each second assembly. For example, in one embodiment, the nanostructure includes 12 first assemblies and 20 second assemblies; in this embodiment, each first assembly can include, for example, 5 copies of the same first polypeptide, and each second assembly can include, for example, 3 copies of the same second polypeptide. In another embodiment, the nanostructure includes 12 first assemblies and 30 second assemblies; in this embodiment, each first assembly can include, for example, 5 copies of the same first polypeptide, and each second assembly can include, for example, 2 copies of the same second polypeptide. In a further embodiment, the nanostructure comprises 20 first assemblies and 30 second assemblies; in this embodiment, each first assembly may comprise, for example, three copies of the same first polypeptide, and each second assembly may comprise, for example, two copies of the same second polypeptide. All of these embodiments are capable of forming a synthetic nanomaterial with regular icosahedral symmetry.

[0057] In another embodiment, the nanostructures of any embodiment or combination of embodiments of the present disclosure have one or more of the following characteristics, each of which is demonstrated in the examples below: (a) binds to a prefusion F-specific antibody, including but not limited to monoclonal antibody D25; (b) forming symmetrical structures, including but not limited to icosahedral structures; (c) stable at 50°C; and / or (d) Stable in 2.25 M guanidine hydrochloride.

[0058] In another aspect, the present disclosure provides a nucleic acid encoding the fusion protein of the present disclosure. The nucleic acid sequence may comprise RNA or DNA. Such nucleic acid sequences may comprise additional sequences useful for facilitating the expression and / or purification of the encoded protein, including, but not limited to, polyA sequences, modified Kozak sequences, and sequences encoding epitope tags, export signals, secretion signals, nuclear localization signals, and plasma membrane localization signals. Based on the teachings herein, it will be clear to those skilled in the art which nucleic acid sequences encode the proteins of the present disclosure.

[0059] In a further aspect, the present disclosure provides an expression vector comprising an isolated nucleic acid of any embodiment or combination of embodiments of the present disclosure operably linked to an appropriate regulatory sequence. Expression vectors include vectors in which a nucleic acid coding region or gene is operably linked to any regulatory sequence capable of conferring expression of the gene product. A "regulatory sequence" operably linked to a nucleic acid sequence of the present disclosure is a nucleic acid sequence capable of conferring expression of the nucleic acid molecule. Regulatory sequences need not be contiguous with the nucleic acid sequence, so long as they function to direct its expression. Thus, for example, a non-translated but transcribed intervening sequence can be present between the promoter sequence and the nucleic acid sequence, and the promoter sequence can still be considered "operably linked" to the coding sequence. Other such regulatory sequences include, but are not limited to, polyadenylation signals, termination signals, and ribosome binding sites. Such expression vectors can be of any type known in the art, including, but not limited to, plasmid and viral expression vectors. The regulatory sequences used to drive expression of the disclosed nucleic acid sequences in mammalian systems can be constitutive (driven by any of a variety of promoters, including but not limited to, CMV, SV40, RSV, actin, EF) or inducible (driven by any of several inducible promoters, including but not limited to, tetracycline-responsive, ecdysone-responsive, steroid-responsive). The construction of expression vectors for use in transfection of prokaryotic cells is also well known in the art and can thus be accomplished by standard techniques.(See, e.g., Sambrook, Fritsch, and Maniatis, in: Molecular Cloning, A Laboratory Manual, Cold Spring Harbor Laboratory Press, 1989; Gene Transfer and Expression Protocols, pp. 109-128, ed. E.J. Murray, The Humana Press Inc., Clifton, NJ), and the Ambion 1998 Catalog (Ambion, Austin, TX). Expression vectors must be replicable in the host organism either as episomes or by integration into the host chromosomal DNA. In preferred embodiments, expression vectors comprise plasmids. However, the present disclosure is intended to include other expression vectors that serve equivalent functions, such as viral vectors.

[0060] In another aspect, the present disclosure provides a host cell transfected with the nucleic acid or expression vector disclosed herein, wherein the host cell can be either a prokaryotic cell or a eukaryotic cell such as a mammalian cell.The cell can be transiently or stably transfected.Such transfection of the expression vector into prokaryotic and eukaryotic cells can be achieved by any technique known in the art, including but not limited to standard bacterial transformation, calcium phosphate co-precipitation, electroporation, or liposome-mediated, DEAE-dextran-mediated, polycation-mediated, or viral-mediated transfection. (See, e.g., Molecular Cloning: A Laboratory Manual (Sambrook, et al., 1989, Cold Spring Harbor Laboratory Press; Culture of Animal Cells: A Manual of Basic Technique, 2nd Ed. (R.I. Freshney, 1987. Liss, Inc. New York, NY)). A method of producing a polypeptide according to the present disclosure is a further part of the present invention. The method includes (a) culturing a host according to this aspect of the disclosure under conditions conducive to expression of the polypeptide, and (b) optionally recovering the expressed polypeptide.

[0061] In a further aspect, the present disclosure provides an immunogenic composition comprising an effective amount of the nanostructure of any embodiment or combination of embodiments of the present disclosure and a pharmaceutically acceptable carrier, which may include (a) a lyoprotectant; (b) a surfactant; (c) a bulking agent; (d) a tonicity adjusting agent; (e) a stabilizer; (f) a preservative, and / or (g) a buffer.

[0062] In some embodiments, the buffer in the pharmaceutical composition is Tris buffer, histidine buffer, phosphate buffer, citrate buffer, or acetate buffer.The composition can also contain a lyoprotectant, such as sucrose, sorbitol, or trehalose.In certain embodiments, the composition contains a preservative, such as benzalkonium chloride, benzethonium chloride, chlorhexidine, phenol, m-cresol, benzyl alcohol, methylparaben, propylparaben, chlorobutanol, o-cresol, p-cresol, chlorocresol, phenylmercuric nitrate, thimerosal, benzoic acid, and various mixtures thereof.In other embodiments, the composition contains a bulking agent, such as glycine. In yet other embodiments, the composition includes a surfactant, such as polysorbate-20, polysorbate-40, polysorbate-60, polysorbate-65, polysorbate-80, polysorbate-85, poloxamer-188, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan trilaurate, sorbitan tristearate, sorbitan trioleate, or a combination thereof. The composition may also include a tonicity adjuster, such as a compound that renders the formulation substantially isotonic or isosmotic with human blood. Exemplary tonicity adjusters include sucrose, sorbitol, glycine, methionine, mannitol, dextrose, inositol, sodium chloride, arginine, and arginine hydrochloride. In other embodiments, the composition further comprises a stabilizer, e.g., a molecule that substantially prevents or reduces chemical and / or physical instability of the nanostructures in lyophilized or liquid form. Exemplary stabilizers include sucrose, sorbitol, glycine, inositol, sodium chloride, methionine, arginine, and arginine hydrochloride.

[0063] The nanostructures may be the only active agent in the composition, or the composition may further include one or more other agents suitable for the intended use, including, but not limited to, adjuvants for generally stimulating the immune system and improving the immune response overall. Any suitable adjuvant can be used. The term "adjuvant" refers to a compound or mixture that enhances the immune response to an antigen. Exemplary adjuvants include Adju-Phos™, Adjumer™, albumin-heparin microparticles, algae glucan, algamulin, alum, antigen formulation, AS-2 adjuvant, autologous dendritic cells, autologous PBMCs, Avridine™, B7-2, BAK, BAY R1005, bupivacaine, bupivacaine-HCl, BWZL, calcitriol, calcium phosphate gel, CCR5 peptide, CFA, cholera holotoxin (CT) and cholera toxin B subunit (CTB), cholera toxin A1-subunit-protein A. D-fragment fusion protein, CpG, CRL1005, cytokine-containing liposomes, D-Murapalmitine, DDA, DHEA, diphtheria toxoid, DL-PGL, DMPC, DMPG, DOC / alum complex, fowlpox, Freund's complete adjuvant, gamma inulin, Gerbu adjuvant, GM-CSF, GMDP, hGM-CSF, hIL-12 (N222L), hTNF-α, IFA, IFN-γ-containing pcDNA3, IL-12 DNA, IL-12 plasmid, IL-12 / GM-CSF plasmid (Sykes), IL-2-containing pcDNA3, IL-2 / Ig plasmid, IL-2 / Ig protein, IL-4, IL-4-containing pcDNA3, Imiquimod™, ImmTher™, immunoliposomes containing antibodies against costimulatory molecules, interferon-γ, interleukin-1β, interleukin-12, interleukin-2, interleukin-7, ISCOM™, Iscoprep 7.0.3™, keyhole limpet hemocyanin, lipid-based adjuvant, liposomes, loxoribine, LT(R192G), LT-OA or LT Oral adjuvant, LT-R192G, LTK63, LTK72, MF59, MONTANIDE ISA 51, MONTANIDE ISA 720, MPL™, MPL-SE, MTP-PE, MTP-PE liposomes, murametide, murapalmitine, NAGO, nCT native cholera toxin, nonionic surfactant vesicles, mCT-E112K, a non-toxic mutant of cholera toxin, p-hydroxybenzoic acid methyl ester, pCIL-10, pCIL12, pCMVmCAT1, pCMVN, Peptomer-NP, Pleuran, PLG, PLGA, PGA, and PLA, Pluronic Adjuvants include, but are not limited to, L121, PMMA, PODDS™, polyrA:polyrU, polysorbate 80, protein cochleate, QS-21, Quadri A saponin, Quil-A, Rehydragel HPA, Rehydragel LV, RIBI, Ribi-like adjuvant systems (MPL, TMD, CWS), S-28463, SAF-1, Sclavo peptides, Sendai proteoliposomes, Sendai-containing lipid matrices, Span 85, Specol, squalane 1, squalene 2, stearyl tyrosine, tetanus toxoid (TT), Theramide™, threonylmuramyl dipeptide (TMDP), Ty particles, and Walter Reed liposomes. The choice of adjuvant depends on the subject being treated. Preferably, a pharmaceutically acceptable adjuvant is used.

[0064] In another aspect, the present disclosure provides a method for generating an immune response to a paramyxovirus and / or pneumovirus F protein in a subject, the method comprising administering to the subject an effective amount of an immunogenic composition of any embodiment or combination of embodiments of the present disclosure to generate an immune response. In a further aspect, the present disclosure provides a method for treating or preventing a paramyxovirus and / or pneumovirus infection in a subject, the method comprising administering to the subject an effective amount of an immunogenic composition of any embodiment or combination of embodiments of the present disclosure, thereby treating or preventing a paramyxovirus and / or pneumovirus infection in the subject.

[0065] In one embodiment, the paramyxovirus and / or pneumovirus comprises respiratory syncytial virus. "Respiratory syncytial virus" and "RSV" refer to negative-sense single-stranded RNA viruses that cause respiratory disease, especially in children. When the method includes treating RSV infection, the immunogenic composition is administered to a subject who is already infected with RSV and / or who is suffering from symptoms that indicate that the subject is likely to be infected with RSV (including but not limited to lower respiratory tract infection, upper respiratory tract infection, bronchiolitis, pneumonia, fever, fatigue, loss of appetite, recurrent wheezing, and asthma). As used herein, "treat" or "treating" includes, but is not limited to, achieving one or more of the following: (a) reducing paramyxovirus and / or pneumovirus titer in a subject; (b) limiting any increase in paramyxovirus and / or pneumovirus titer in a subject; (c) reducing the severity of paramyxovirus and / or pneumovirus symptoms; (d) limiting or preventing the onset of paramyxovirus and / or pneumovirus symptoms following infection; (e) inhibiting the worsening of paramyxovirus and / or pneumovirus symptoms; (f) limiting or preventing the recurrence of paramyxovirus and / or pneumovirus symptoms in a subject who previously exhibited symptoms of paramyxovirus and / or pneumovirus infection; and / or promoting maternal transmission of paramyxovirus and / or pneumovirus antibodies to the infant (following maternal immunization).

[0066] When the method includes the step of restricting paramyxovirus and / or pneumovirus infection, the immunogenic composition is administered prophylactically to a subject who is not known to be infected with paramyxovirus and / or pneumovirus but is considered to be at risk of exposure to them.As used herein, " restricting " means restricting RSV infection in a subject who is at risk of RSV infection.Particularly high-risk groups include children under 18 years old (especially infants under 3 years old), adults over 65 years old, and individuals suffering from any type of immunodeficiency.

[0067] As used herein, "effective amount" refers to an amount of an immunogenic composition effective in treating and / or limiting RSV infection. The immunogenic composition is typically formulated as a pharmaceutical composition, such as the pharmaceutical compositions disclosed above, and can be administered via any suitable route, including orally, parenterally, by inhalation spray, rectally, or topically, in a dosage unit formulation containing conventional pharmaceutically acceptable carriers, adjuvants, and vehicles. As used herein, the term parenteral includes subcutaneous, intravenous, intraarterial, intramuscular, intrasternal, intratendinous, intraspinal, intracranial, intrathoracic, infusion, or intraperitoneal. The polypeptide composition can also be administered via microspheres, liposomes, immune stimulating complexes (ISCOMs), or other microparticle delivery systems or sustained-release formulations introduced into appropriate tissues (such as blood). Dosage regimens can be adjusted to provide the optimal desired response (e.g., therapeutic or prophylactic). A suitable dosage range may be, for example, 0.1 ug / kg body weight to 100 mg / kg body weight of F protein or antigenic fragment thereof. The composition may be delivered in a single bolus, or may be administered two or more times (e.g., two, three, four, five, or more times) as determined by the attending physician.

[0068] In one embodiment, administration results in the production of paramyxovirus and / or pneumovirus neutralizing antibodies in the subject. In another embodiment, the neutralizing antibodies are expressed in the serum of the subject at a titer of at least 1,000 (1 / ID50 ) in other embodiments, neutralizing antibodies are present in the subject's serum at a titer of 2,000 or 5,000. [Example]

[0069] Expression and purification of DS-Cav1-I53_dn5B fusion protein Expression of each construct design shown in Figure 1, corresponding to SEQ ID NOs: 5-11, was tested. The constructs contained an N-terminal secretion signal (SEQ ID NO: 20) and C-terminal purification tags including a TEV cleavage site, a Myc tag, and a His tag. The complete construct containing these tags is as follows: TIFF0007818504000028.tif184146TIFF0007818504000029.tif222146TIFF0007818504000030.tif19146

[0070] On day 0, 1 mL of HEK293F cell culture was transiently transfected with 1 μg / mL plasmid DNA and incubated at 37°C, 8% CO2, and 70% humidity with shaking at 125 rpm. On day 5, cells were harvested by centrifugation at 4000 g for 5 minutes at room temperature. The supernatant was sterile filtered (0.45 μm), and the cells were discarded.

[0071] To screen for secretion of the DS-Cav1-I53_dn5B fusion protein, 50 μL of each cell supernatant was directly plated (undiluted) onto a MaxiSorp 96-well ELISA plate (Thermo Fisher) and incubated for 1 hour with shaking at room temperature. The plate was washed six times with Tris-buffered saline (TBS) containing 0.05% Tween 20 (wash buffer). The remaining unbound surfaces of the wells were blocked with 200 μL of wash buffer (blocking buffer) containing 4% nonfat milk (Bio-Rad, blotting-grade blocker) per well and incubated for 1 hour with shaking at room temperature. The plate was washed six times with wash buffer. D25 monoclonal antibody (mAb) was diluted to 0.2 μg / mL in block buffer, and 200 μL was plated into each sample well and incubated for 1 hour with shaking at room temperature. The plate was again washed six times with wash buffer. Horseradish peroxidase (HRP)-conjugated anti-human secondary antibody (Abcam) was diluted 1:20,000 in blocking buffer, and 200 μL was plated into each sample well. The plate was again incubated at room temperature with shaking for 1 hour. The plate was washed again as described above. ABTS HRP substrate (Fisher Scientific) was equilibrated to room temperature, and 150 μL was plated into each sample well and incubated at room temperature for approximately 15 minutes. The absorbance at 405 nm was immediately measured using a SpectraMax™ M3 plate reader. Figure 2 shows the average absorbance at 405 nm of biological triplicate measurements obtained from supernatants of cultures expressing RSV_F-dn5B_04, RSV_F-dn5B_05, RSV_F-dn5B_06, and RSV_F-dn5B_07. RSV_F-dn5B_07 yielded approximately three times more protein in the supernatant than the other constructs.

[0072] Expression of RSV_F-dn5B_07 for purification was performed similarly to the expression screening described above, except that 200 mL of culture medium was transfected instead of 1 mL for scale-up cultivation. To purify components using immobilized metal affinity chromatography (IMAC), 1 mL of Ni-Excel resin (GE Healthcare) was first equilibrated with 25 mM Tris pH 8.0, 250 mM NaCl, 5% glycerol, and 20 mM imidazole (wash buffer) and then resuspended in 1 mL of wash buffer to a total of 2 mL of resin slurry. The 2 mL of resin slurry was then added to the harvested cell supernatant obtained from expression and incubated at 4°C for 1 hour with gentle rocking. The cell supernatant-resin mixture was applied to an empty IMAC™ gravity column (BioRad catalog #7321010) to allow unbound host cell contaminants to pass through. Ten column volumes of wash buffer were added to the resin bed to remove remaining contaminants. Finally, the components were eluted with 5 column volumes of elution buffer (25 mM Tris pH 8.0, 250 mM NaCl, 5% glycerol, 500 mM imidazole).

[0073] The components were further purified using size-exclusion chromatography (SEC) as follows. First, a Superdex™ 200 Increase 10 / 300 GL SEC column (GE Healthcare) was equilibrated with 1.2 column volumes of elution buffer (25 mM Tris pH 8.0, 250 mM NaCl, 5% glycerol) on an AKTA Pure™ FPLC (GE Healthcare). The IMAC eluate was concentrated to 1 mL using a 10K MWCO concentrator (Amicon, Sartorius) and then sterilized using a 0.22 μm filter. The sample was applied to the SEC column, and the components were eluted by passing 1.2 column volumes of elution buffer through the column using the FPLC, maintaining a flow rate of 0.75 mL / min. The protein of interest eluted at approximately 15 mL.

[0074] Antigenicity of RSV_F-dn5B_07 (construct 387) Purified RSV_F-dn5B_07(387) was diluted to 200 nM in HPS-EP+ buffer (ForteBio) containing 0.5% nonfat milk (BioRad, blotting-grade blocker), and 200 μL was plated into three wells of a black 96-well plate (Grenier). Palivizumab (Pali), AM14, and 4D7 monoclonal antibodies (mAbs) were diluted to 10 μg / mL in HPS-EP+ buffer containing 0.5% milk, and 200 μL of each mAb was plated into a well of a black 96-well plate. Using a biolayer interference (BLI) device (Octet, Red 96), a Protein A biosensor (ForteBio) was immersed in the mAb well to immobilize the antibody. The biosensor was then immersed in a buffer solution (see dilution buffer) to obtain a baseline, and then immersed in the sample well to observe binding (association). Finally, the biosensor was again immersed in a buffer solution to observe any potential dissociation of the sample from the mAb. Figure 3A shows the binding and dissociation curves for the binding of palivizumab, AM14, and 4D7 to RSV_F-dn5B_07 (387). Both palivizumab and AM14 bind to RSV_F-dn5B_07 (387), while 4D7 cannot bind to the antigen. AM14 is a prefusion and trimer-specific mAb (Gilman et al., PLoS Pathog. 2015 Jul 10; 11(7):e1005035. doi: 10.1371 / joumal.ppat.1005035. eCollection 2015), whereas 4D7 is specific for a prefusion conformation and a mutually exclusive RSV F conformation (Flynn et al., 2016, PLoS One. 2016 Oct 20; 11(10):e0164789. doi: 10.1371 / joumal.pone.0164789. eCollection 2016). These data indicate that the RSV F portion of RSV_F-dn5B_07 (387) is exclusively in the prefusion conformation.

[0075] Retention of mAb binding after thermal stress The stability of RSV F prefusion conformations is often assayed by determining the percentage of prefusion-specific mAb binding that is retained after incubating the antigen at elevated temperatures for 1 hour (Joyce et al., Nat Struct Mol Biol. 2016 Sep;23(9):811-820. doi: 10.1038 / nsmb.3267. Epub 2016 Aug 1; Marcandalli et al., Cell. 2019 Mar 7;176(6):1420-1431.e17. doi: 10.1016 / j.cell.2019.01.046). The prefusion stability of RSV_F-dn5B_07 (387) was compared to that of our previously described DS-Cav1-I53-50A (309) protein. The concentrations of 309 and 387 were normalized to 0.16 mg / mL (2 μM) using dPBS containing 5% glycerol as the diluent. Samples were incubated in a thermal cycler at 20, 50, 70, or 80°C for 1 hour. After incubation, samples were diluted 10-fold to 200 nM with HPS-EP+ buffer (ForteBio) containing 0.5% nonfat milk (BioRad, blotting-grade blocker), and then 200 μL of each was plated into a black 96-well plate (Grenier). D25 monoclonal antibody (mAb) was diluted to 10 μg / mL with HPS-EP+ buffer containing 0.5% milk, and 200 μL of mAb was plated into eight wells of a black 96-well plate. Using a biolayer interferometry (BLI) instrument (Octet, Red 96), a Protein A biosensor (ForteBio) was immersed in the mAb well to immobilize the antibody on the biosensor. The biosensor was then immersed in a buffer solution (see dilution buffer) to obtain a baseline, and then immersed in the sample well to observe binding (association). Finally, the biosensor was again immersed in buffer to observe any potential dissociation of the sample from the mAb. Relative binding was calculated using the ratio of the binding at 1500 seconds after incubation at 50, 70, or 80°C to the binding at 1500 seconds after incubation at 20°C. Figure 4A shows the binding and dissociation curves for each sample.Figure 4B shows a bar graph depicting the partial reactivity at each elevated temperature. The data indicate that 387 retains higher D25 binding than 309 after 1 hour at 50 ° C. Both proteins lose most of their D25 binding at 70 or 80 ° C. The data indicate that the pre-fusion conformation of the RSV F antigen is more stable in 387 than in 309.

[0076] Expression and purification of I53_dn5A in a bacterial expression system To express the I53_dn5A component, a plasmid containing the following in 5' to 3' order was cloned into BL21 * The vector was transformed into (DE3) competent cells (New England Biolabs) containing the NdeI restriction enzyme site, ORF, XhoI restriction enzyme site, and 6xHis tag in the pET29b+ vector. A starter culture was prepared in Terrific Broth (TB) containing 50 μg / mL kanamycin by transferring a bacterial colony to the medium. The starter culture was incubated overnight (approximately 16 hours) at 37°C with shaking at 250 rpm. TB containing 50 μg / mL kanamycin was used for the expression culture. The expression culture was incubated at 37°C for approximately 2 hours with shaking at 250 rpm until the optical density (OD600) reached 0.6-0.8, at which point expression was induced by the addition of 1 mM IPTG. The culture was then incubated at 18°C ​​for an additional 18 hours. A 500 mL expression culture was generated in a 2 L baffled shake flask (yield: approximately 0.1 g / L). Cells were harvested by centrifugation at 4000 g for 15 minutes, the medium was decanted and the cell pellet was stored at -20°C until purification.

[0077] To purify components from host cell contaminants, the cell pellet was first resuspended in 20 mL of lysis buffer (25 mM Tris pH 8.0, 150 mM NaCl, 5% glycerol) and homogenized using a ThunderStick™ at 10,000 rpm for 30 seconds. Cells were lysed using a microfluidizer at 18,000 psi. The lysate was clarified by centrifugation at 24,000 g for 30 minutes at 4°C, and the supernatant was then sterile filtered at 0.22 μm, and the pellet was discarded. The filtrate was purified using immobilized metal affinity chromatography (IMAC) as follows: First, the clarified lysate was applied to a 2 mL Ni2+-NTA column bed volume after equilibrating the resin in 25 mM Tris pH 8.0, 150 mM NaCl, 30 mM imidazole, 5% glycerol (wash buffer). The column was then cleared of host cell proteins by applying 12 column volumes of wash buffer to the resin bed, and finally components were eluted from the resin with 7 column volumes of elution buffer (25 mM Tris pH 8.0, 150 mM NaCl, 500 mM imidazole, 5% glycerol).

[0078] To further purify the protein of interest, size exclusion chromatography (SEC) was performed as follows. First, a Superdex™ 200 Increase 26 / 600 GL SEC column (GE Healthcare) was equilibrated with 1.2 column volumes of elution buffer (25 mM Tris pH 8.0, 150 mM NaCl, 5% glycerol) on an AKTA Pure™ FPLC (GE Healthcare). The IMAC™ eluate was concentrated to 10 mL using a 10K MWCO concentrator (Amicon, Sartorius) and then sterilized using a 0.22 μm filter. Using the sample pump on the FPLC, the sample was applied to the SEC column at a flow rate of 3.2 mL / min. Finally, components were eluted by passing 1.2 column volumes of elution buffer through the column using the FPLC while maintaining a flow rate of 3.2 mL / min. The protein of interest eluted at approximately 210 mL.

[0079] In vitro assembly of DS-Cav1-I53_dn5 nanostructures Nanoparticles were assembled using purified RSV_F-dn5B_07 trimer and purified I53_dn5A pentamer components by mixing 50 μM of each component in a 1:1 molar ratio (calculated according to the subunit, not the oligomer) in a 1 mL reaction. The assembly reaction was set up as follows: First, the trimer component was added to a 1.5 mL microcentrifuge tube, followed by the addition of buffer (25 mM Tris pH 8, 250 mM NaCl, 5% glycerol) to the tube, followed by the pentamer component. The reaction was incubated at 4°C for approximately 1 hour, after which dynamic light scattering (DLS) readings were collected as follows: Particle size measurements were performed at 25°C using a DynaPro™ Nanostar (Wyatt Technology Corp.) equipped with a 1 μL quartz cuvette. Samples were measured in triplicate, with 10 acquisitions per measurement, and each acquisition taking 5 seconds, using automatic laser attenuation. Figure 5 shows that the crude in vitro assembly reaction contained a major product with the predicted radius (23 nm) and low polydispersity, indicating successful assembly into the targeted icosahedral nanostructures.

Claims

1. (a) a plurality of first assemblies, each first assembly comprising a plurality of identical first polypeptides, the first polypeptides having the sequence of SEQ ID NO:2, in which the parenthesized residues are optional: a plurality of first assemblies comprising the amino acid sequence of (b) a plurality of second assemblies, each second assembly comprising a plurality of identical second polypeptides, the second polypeptides having the sequence of SEQ ID NO:1, in which the parenthesized residues are optional: a plurality of second assemblies comprising the amino acid sequence of A nanostructure comprising: the plurality of first assemblies non-covalently interacting with the plurality of second assemblies to form a nanostructure; the nanostructure displays multiple copies of one or more paramyxovirus and / or pneumovirus F proteins or antigenic fragments thereof on the exterior surface of the nanostructure; and The nanostructure, wherein the F protein or antigenic fragment thereof of the one or more paramyxoviruses and / or pneumoviruses comprises the amino acid sequence of SEQ ID NO:

37.

2. The nanostructure of claim 1, wherein the F protein or antigenic fragment of one or more paramyxoviruses and / or pneumoviruses is expressed as a fusion protein with the first polypeptide and / or the second polypeptide.

3. 3. The nanostructure of claim 2, wherein the plurality of first assemblies each comprise the same fusion protein and / or the plurality of second assemblies each comprise the same fusion protein.

4. 2. The nanostructure of claim 1, wherein the F protein or antigenic fragment thereof of one or more paramyxoviruses and / or pneumoviruses is expressed as a fusion protein with the first polypeptide.

5. The nanostructure of claim 4, wherein each of the plurality of first assemblies comprises the same fusion protein.

6. The nanostructure of any one of claims 2 to 5, wherein the plurality of first and / or second assemblies comprises F proteins or antigenic fragments thereof of a total of two or more types of paramyxovirus and / or pneumovirus expressed as fusion proteins with the first polypeptide and / or the second polypeptide.

7. The nanostructure of any one of claims 2 to 6, wherein only a subset of the first and / or second polypeptides comprises a fusion protein with an F protein or an antigenic fragment thereof.

8. The nanostructure of any one of claims 1 to 7, wherein each first assembly comprises a homotrimer of the first polypeptide.

9. The nanostructure of any one of claims 1 to 8, wherein each second assembly comprises a homopentamer of the second polypeptide.

10. The nanostructure of any one of claims 2 to 9, wherein each fusion protein comprises an amino acid linker positioned between the first polypeptide and the F protein or antigenic fragment thereof of the one or more paramyxoviruses and / or pneumoviruses, and / or an amino acid linker positioned between the second polypeptide and the F protein or antigenic fragment thereof of the one or more paramyxoviruses and / or pneumoviruses.

11. The nanostructure of claim 10, wherein the amino acid linker sequence comprises one or more trimerization domains.

12. The sequence of the amino acid linker is the amino acid sequence 12. The nanostructure of claim 10 or 11, comprising:

13. The sequence of the amino acid linker is the amino acid sequence 12. The nanostructure of claim 10 or 11, comprising a GCN4 coiled-coil domain, including but not limited to:

14. the sequence of the amino acid linker is a Gly-Ser linker, or 11. The nanostructure of claim 10, comprising a linker selected from the group consisting of:

15. The nanostructure of any one of claims 2 to 14, wherein the fusion protein comprises an amino acid sequence having at least 90% sequence identity to an amino acid sequence selected from the group consisting of SEQ ID NOs: 5 to 11.

16. (a) binds to a prefusion F-specific antibody; (b) forming symmetrical structures, including but not limited to icosahedral structures; (c) is stable at 50°C; and / or (d) stable in 2.25 M guanidine hydrochloride; The nanostructure according to any one of claims 1 to 15.

17. A nucleic acid encoding a fusion protein as recited in any one of claims 2 to 14.

18. 18. The nucleic acid of claim 17, wherein the fusion protein comprises the amino acid sequence of SEQ ID NO:

11.

19. 19. An expression vector comprising the nucleic acid of claim 17 or 18 operably linked to a promoter.

20. A host cell comprising the nucleic acid or expression vector of any one of claims 17 to 19.

21. An immunogenic composition comprising the nanostructure of any one of claims 1 to 16 and a pharmaceutically acceptable carrier.

22. 22. The immunogenic composition of claim 21, further comprising an adjuvant.

23. A nanostructure described in any one of claims 1 to 16 or an immunogenic composition described in claim 21 or 22 for use in a method for generating an immune response to an F protein of a paramyxovirus and / or pneumovirus in a subject, or for use in a method for treating or limiting a paramyxovirus and / or pneumovirus infection in a subject, the method comprising administering an effective amount of the nanostructure or immunogenic composition to a subject in need thereof.

24. 24. The nanostructure or immunogenic composition of claim 23, wherein said administration results in the production of paramyxovirus and / or pneumovirus neutralizing antibodies in said subject.

25. The neutralizing antibody has a titer of at least 1,000 (1 / ID 50 25. The nanostructure or immunogenic composition of claim 24, wherein the nanostructure or immunogenic composition is present in the serum of the subject at a concentration of 0.1% or more.

26. 17. A method for assembling nanostructures in vitro according to any one of claims 1 to 16, comprising mixing the plurality of first assemblies with the plurality of second assemblies under aqueous conditions to drive spontaneous assembly of desired nanostructures.

27. 27. The method of claim 26, wherein the mixing step comprises mixing a first assembly comprising a first polypeptide, each comprising an F protein or an antigenic fragment thereof, with a suitable second assembly comprising a second polypeptide, in an approximately 1:1 molar ratio of first polypeptide to second polypeptide, under conditions and for a time suitable to allow the first assembly and the second assembly to interact to form the nanostructure.

28. 28. The method of claim 27, wherein the mixing step comprises mixing a first assembly comprising a first polypeptide, wherein fewer than all of the first polypeptides comprise an F protein, with a suitable second assembly comprising a second polypeptide, in an approximately 1:1 molar ratio of first polypeptide to second polypeptide, under conditions and for a time suitable to allow interaction of the first assembly and the second assembly to form the nanostructure.

29. 29. The method of claim 27 or 28, wherein the mixing step comprises mixing first assemblies comprising first polypeptides each comprising an F protein, wherein the first polypeptides collectively comprise a plurality of different F proteins, with an appropriate second assembly comprising second polypeptides, in a first polypeptide:second polypeptide molar ratio of approximately 1:1, under conditions and for a time suitable to allow the first and second assemblies to interact to form the nanostructure comprising a plurality of F proteins or antigenic fragments thereof.

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