vaccine

Abstract

The present disclosure relates to methods of inducing a pan-salveolar coronavirus variant immune response for the treatment and prevention of coronavirus infection.

Description

[Technical Field]

[0001] The present disclosure relates to immunogenic compositions useful for generating a pan-sarbecoronavirus immune response as part of a prime-boost vaccination regimen. [Background technology]

[0002] Although numerous vaccines have been approved for the treatment of COVID-19, data suggest that vaccination efficacy may vary across variants. Since the first description of SARS-CoV-2, there has been the evolution of multiple variants of concern. Therefore, a vaccine targeting multiple strains of SARS-CoV-2 could be highly beneficial for immunization against COVID-19.

[0003] However, a phenomenon known as "antigenic sin" has been observed, where dominant epitopes from an initial prime vaccination are recalled in a boost vaccination, even when the boost vaccination is directed against a different variant. This poses a challenge in achieving a broad neutralizing response against multiple variants.

[0004] Antigen-presenting nanoparticles have been proposed as vaccines to elicit broadly neutralizing responses against highly mutable viruses such as salve coronaviruses or influenza.

[0005] The premise of this strategy is that virus-like particles (VLPs) can present multiple variants of antigens derived from viruses such as SARS-CoV-2. Presenting multiple antigens can generate an immune response against conserved epitopes, thereby limiting the possibility of immunological escape through mutation.

[0006] This approach has been successfully used in many in vivo preclinical vaccination studies. For example, Boyoglu-Barnum et al. (Nature, 592; 623-628 (2021)) show that tetravalent HA-VLPs induce broad protection against influenza. Cohen et al. (Science, 377, eabq0839 (2022)) show that nanoparticles displaying eight different salvecoronavirus spike receptor-binding domains protect against challenge with diverse salvecoronaviruses in animal models. Thus, this approach is promising.

[0007] However, these examples of broadly neutralizing responses are achieved using protein-based nanoparticle vaccines, which require expensive and complex manufacturing processes. This contrasts with mRNA vaccines, which are generally cheaper to produce, have a much more robust manufacturing process, and are highly advantageous when vaccine modifications are required in response to immunological escape. One drawback associated with mRNA is the general size limit of the vaccine that can be administered. For example, it can be difficult to develop an mRNA vaccine that encodes up to eight different antigen sequences, each of which is fused to a multimerization element that allows VLPs to form.

[0008] It is therefore desirable to develop a vaccine that combines the advantages of both mRNA technology and the broad neutralization achieved with multivalent antigen nanoparticles. Summary of the Invention

[0009] The present disclosure relates to immunogenic compositions useful for generating a pan-salvecoronavirus immune response as part of a prime-boost vaccination regimen, which comprise mRNA encoding a single spike protein from a salvecoronavirus variant along with coding sequences for multimerization units that form multimeric complexes upon assembly in vivo.

[0010] Specific examples of the present disclosure are summarized below: This list is illustrative only and is not intended to be an exhaustive list of all examples provided by the present disclosure.

[0011] 1. A method for inducing a pan-sarbecoronavirus variant immune response in an individual who has previously received one or more doses of a first SARS-CoV-2 vaccine against one or more first sarbecoronavirus variants (variant 1), the method comprising administering to the individual one or more doses of a second SARS-CoV-2 vaccine, the second SARS-CoV-2 vaccine comprising mRNA encoding a single spike (S) protein or an immunogenic fragment or immunogenic variant thereof from a sarbecoronavirus variant (variant 2) different from variant 1, wherein the S protein is encoded as an S protein-multimerization subunit fusion, and the method induces a pan-variant immune response against sarbecoronavirus variant 1 and variant 2 in the individual, and induces an immune response to one or more additional sarbecoronavirus variants different from variant 1 and variant 2. 2. The method of clause 1, wherein the S protein-multimerization subunit fusion is a protein-ferritin subunit fusion. 3. The method of clause 1 or clause 2, wherein the mRNA of the second SARS-CoV-2 vaccine is formulated in a lipid nanoparticle (LNP). 4. The method of any one of clauses 1 to 3, wherein variant 2 is SARS-CoV-2 omicron BA.4 / 5. 5. The method of clause 4, wherein the second SARS-CoV-2 vaccine comprises the mRNA sequence of SEQ ID NO: 11. 6. The method of any one of clauses 1 to 3, wherein variant 2 is SARS-CoV-2 Omicron XBB.1.5. 7. The method of clause 6, wherein the second SARS-CoV-2 vaccine comprises the mRNA sequence of SEQ ID NO: 17. 8. The method of any one of clauses 1 to 7, wherein the first SARS-CoV-2 vaccine does not comprise a nucleic acid encoding a salvecoronavirus S protein in the form of a fusion protein in vivo capable of assembling to form nanoparticles. 9. The method of any one of clauses 1 to 8, wherein the method induces an immune response against one or more additional salvecoronavirus variants that are mutationally distinct from variant 1 and / or variant 2. 10. The method of any one of clauses 1 to 9, wherein the second SARS-CoV-2 vaccine is a monovalent vaccine. 11. The method of any one of clauses 1 to 9, wherein the second SARS-CoV-2 vaccine is a bivalent vaccine comprising an additional mRNA encoding a single spike (S) protein or an immunogenic fragment or immunogenic variant thereof, wherein the S protein is encoded as an S protein-multimerized subunit fusion and is distinct from variant 2 and is derived from the same or a different salve coronavirus variant as variant 1. 12. The method of any one of clauses 1-11, wherein the first dose of the second SARS-CoV-2 vaccine is administered to the individual at least 4 months after administration of the final dose of the first SARS-CoV-2 vaccine. 13. The method of clause 12, wherein the first dose of the second SARS-CoV-2 vaccine is administered to the individual at least 6 months after administration of the final dose of the first SARS-CoV-2 vaccine. 14. An immunogenic composition comprising mRNA encoding a single spike (S) protein, or an immunogenic fragment or immunogenic variant thereof, from a first salvecoronavirus variant for use in inducing a pan-salvecoronavirus variant immune response in an individual who has previously received one or more doses of a first SARS-CoV-2 vaccine comprising or encoding an immunogen from a second salvecoronavirus variant, the S protein is encoded as an S protein-multimerization subunit fusion; An immunogenic composition for use, wherein the immunogenic composition is used to induce an immune response against a first salvecoronavirus variant and a second salvecoronavirus variant, and against at least a third salvecoronavirus variant. 15. The immunogenic composition for use according to clause 14, wherein the S protein-multimerization subunit fusion is a protein-ferritin subunit fusion. 16. The immunogenic composition for use according to clause 14 or 15, wherein the mRNA is formulated in a lipid nanoparticle (LNP). 17. The immunogenic composition for use according to any one of clauses 14 to 16, wherein the first salve coronavirus variant is SARS-CoV-2 Omicron BA.4 / 5. 18. The immunogenic composition for use according to clause 17, wherein the mRNA comprises or consists of the mRNA sequence of SEQ ID NO: 11. 19. The immunogenic composition for use according to any one of clauses 14 to 16, wherein the first salve coronavirus variant is SARS-CoV-2 Omicron XBB.1.5. 20. The immunogenic composition for use according to clause 19, wherein the mRNA comprises or consists of the mRNA sequence of SEQ ID NO: 17. 21. The immunogenic composition for use according to any one of clauses 14 to 20, wherein the first SARS-CoV-2 vaccine does not comprise a nucleic acid encoding a salvecoronavirus S protein in the form of a fusion protein capable of assembling in vivo to form nanoparticles. 22. The immunogenic composition for use according to any one of clauses 14 to 21, wherein the third salvecoronavirus variant is mutationally distinct from the first salvecoronavirus variant and / or the second salvecoronavirus variant. 23. An immunogenic composition for use according to any one of clauses 14 to 22, wherein the immunogenic composition is a monovalent composition. 24. The immunogenic composition for use according to any one of clauses 14 to 22, wherein the immunogenic composition is a bivalent composition further comprising mRNA encoding a single spike (S) protein, or an immunogenic fragment or immunogenic variant thereof, wherein the S protein is encoded as an S protein-multimerized subunit fusion and is derived from a sarcocoronavirus variant that is different from said first sarcocoronavirus variant and that is the same as or different from said second sarcocoronavirus variant. [Brief explanation of the drawings]

[0012] Those skilled in the art will understand that the drawings, described below, are for illustrative purposes only and are not intended to limit the scope of the present teachings in any way. [Figure 1] Figure 1 shows improved pan-mutant immunogenicity in mice vaccinated with mRNA molecules according to the present disclosure encoding either the Wuhan D614G antigen fused to ferritin via a linker (Group 2), the BA.4 / 5 antigen fused to ferritin via a linker (Group 3), or a combination of the two (Wuhan D614G and BA.4 / 5 antigens fused to ferritin via a linker; Group 4) compared to two native spike antigens (Wuhan D614G and BA.4 / 5; Group 1). Figure 1a shows neutralizing antibody titers against the BA.4 / 5 pseudovirus on day 180. Figure 1b shows neutralizing antibody titers 14 days after the third vaccination (administered on day 231 as shown in Figure 2). The numbers below each data bar indicate the geometric mean titer. Figure 1c shows neutralizing antibody titers measured among vaccine-experienced mice (similar study design to that shown in Figure 2) 14 days after the third vaccination with either native XBB.1.5 spike protein as a VLP antigen or mRNA molecules encoding the XBB.1.5 spike protein. Numbers within each data bar indicate geometric mean titers. [Figure 2] FIG. 1 shows a schematic diagram of the boost vaccination mouse study design. [Figure 3]FIG. 1 shows neutralizing antibody titers against a panel of mutant pseudoviruses elicited by mRNA-native delta or mRNA-VLP delta vaccines in non-human primates 14 days after the second mRNA immunization. [Figure 4] 1 shows the persistence of neutralizing antibody titers against Delta mutant pseudoviruses elicited by mRNA-native Delta or mRNA-VLP Delta vaccines in non-human primates up to 196 days after initial mRNA immunization. [Figure 5] FIG. 1 shows the frequency of spike-specific memory B cells generated by mRNA-native delta or mRNA-VLP delta vaccines in non-human primates immediately before and 28 days after the second immunization. [Figure 6] 1 shows the enumeration of long-lived antibody-secreting cells in the bone marrow of non-human primates 196 days after the first immunization with mRNA-native delta or mRNA-VLP delta vaccines. [Figure 7] FIG. 1 shows the frequency of spike-specific memory CD4+ T cells generated by mRNA-native delta or mRNA-VLP delta vaccines in non-human primates 28 days after the second immunization. [Figure 8] FIG. 1 shows a schematic diagram of the boost vaccination non-human primate study design. [Figure 9] Neutralizing antibody titers against the ancestral Wuhan_D614G mutant pseudovirus elicited by mRNA-native XBB.1.5 or mRNA-VLP XBB.1.5 vaccines in vaccinated non-human primates measured immediately before (day 246) and 14 days after (day 260) the third immunization. [Figure 10] Neutralizing antibody titers against Omicron BA.4 / 5 mutant pseudovirus elicited by mRNA-native XBB.1.5 or mRNA-VLP XBB.1.5 vaccines in vaccinated non-human primates measured immediately before (day 246) and 14 days after (day 260) the third immunization. [Figure 11]Neutralizing antibody titers against Omicron XBB.1.5 mutant pseudovirus elicited by mRNA-native XBB.1.5 or mRNA-VLP XBB.1.5 vaccines in vaccinated non-human primates measured immediately before (day 246) and 14 days after (day 260) the third immunization. [Figure 12] Figure 1 shows the fold increase in neutralizing antibody (nAb) titers 14 days after the third immunization against different mutant pseudoviruses tested among vaccinated non-human primates given either the mRNA-native XBB.1.5 or mRNA-VLP XBB.1.5 vaccine. DETAILED DESCRIPTION OF THE INVENTION

[0013] All references cited are incorporated herein by reference in their entirety.

[0014] Many modifications and other examples of the disclosures set forth herein will come to mind to one skilled in the art to which these disclosures pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. It is to be understood, therefore, that the disclosure is not to be limited to the particular examples disclosed, and that modifications and other examples are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

[0015] Units, prefixes, and symbols may be shown in their SI accepted form. Unless otherwise indicated, nucleic acids are written left to right in 5' to 3' orientation. Amino acid sequences are written left to right in amino to carboxy orientation. Numeric ranges are inclusive of the numbers defining the range. Amino acids may be referred to herein by either their commonly known three letter symbols or the one-letter symbols recommended by the IUPAC-IUB Biochemical Nomenclature Commission. Nucleotides may likewise be referred to by their commonly accepted one-letter codes. The terms defined below are more fully defined by reference to the specification in its entirety.

[0016] definition The term "nucleic acid sequence" is intended to encompass polymers of DNA or RNA, i.e., polynucleotides, which may be single- or double-stranded and may contain non-natural or altered nucleotides, such as modified uridines. As used herein, the terms "nucleic acid" and "polynucleotide" refer to polymeric forms of nucleotides of any length, either ribonucleotides (RNA) or deoxyribonucleotides (DNA). These terms refer to the primary structure of the molecule and thus include double- and single-stranded DNA, as well as double- and single-stranded RNA. The terms include, as equivalents, analogs of either RNA or DNA made from nucleotide analogs, and modified polynucleotides, including, but not limited to, methylated and / or capped polynucleotides. Nucleic acids are typically linked via phosphate linkages to form nucleic acid sequences or polynucleotides, although many other linkages are known in the art (e.g., phosphorothioates, boranophosphates, etc.).

[0017] The terms "polypeptide," "peptide," and "protein" are used interchangeably herein to refer to polymers of amino acids of any length. A polymer may be linear or branched, may comprise modified amino acids, and may be interrupted by non-amino acids. These terms encompass amino acid polymers that are naturally occurring or modified by any other manipulation or modification, such as, for example, disulfide bond formation, glycosylation, lipidation, acetylation, phosphorylation, or conjugation with a labeling component. Also included within the definition are polypeptides containing one or more analogs of an amino acid (including, for example, unnatural amino acids), as well as other modifications known in the art. Because the polypeptides of the present disclosure are based on antibodies, it is understood that in some aspects the polypeptides can occur as single chains or associated chains.

[0018] "5'-untranslated region (5'-UTR)" has the usual meaning recognized by those skilled in the art. It is a region of a nucleic acid molecule located 5' of a coding sequence that is not translated into protein. The 5'-UTR usually begins at the transcription start site and ends before the start codon of the coding sequence.

[0019] "3'-untranslated region (3'-UTR)" has the usual meaning recognized by those skilled in the art. It is a region of a nucleic acid molecule located 3' of a coding sequence and not translated into protein. The 3'-UTR is usually 3' of the coding sequence. If the molecule contains a polyadenylation signal, the 3'-UTR is usually between the coding sequence and the polyadenylation signal.

[0020] A "coding sequence" is a contiguous stretch of DNA or RNA beginning with a start codon (e.g., methionine (ATG or AUG)) and ending with a stop codon (e.g., TAA, TAG, or TGA, or UAA, UAG, or UGA). A coding sequence typically encodes a polypeptide. The coding sequences disclosed herein are operably linked to 5' and 3' UTRs as described herein.

[0021] "Messenger RNA (mRNA)" is any RNA that encodes (at least one) protein (a polymer of naturally occurring, non-naturally occurring, or modified amino acids) and can be translated to produce the encoded protein in vitro, in vivo, in situ, or even ex vivo. Those of skill in the art will understand that, unless otherwise specified, the nucleic acid sequences described in this application may recite a "T" in a representative DNA sequence, but when the sequence represents RNA (e.g., mRNA), the "T" is replaced with a "U." Thus, any DNA disclosed herein and identified by a specific sequence identification number also discloses the corresponding RNA (e.g., mRNA) sequence complementary to that DNA, in which each "T" in the DNA sequence is replaced with a "U."

[0022] "Nucleoside" refers to a compound containing a sugar molecule (e.g., pentose or ribose) or its derivative in combination with an organic base (e.g., a purine or pyrimidine) or its derivative (also referred to herein as a "nucleobase"). Nucleic acids can contain one or more regions of linked nucleosides. Such regions can have variable backbone linkages. The linkages can be standard phosphodiester linkages, in which case the nucleic acid comprises a region of nucleotides ("nucleotide" refers to a nucleoside containing a phosphate group).

[0023] "Expression" of a nucleic acid sequence refers to one or more of the following events: (1) production of an RNA template from a DNA sequence (e.g., by transcription); (2) processing of the RNA transcript (e.g., by splicing, editing, 5' capping, and / or 3' end processing), and (3) translation of the RNA into a polypeptide or protein.

[0024] The term "pharmaceutical composition" refers to a preparation that is in a form that allows the biological activity of the active ingredient to be effective and that does not contain additional ingredients that are unacceptably toxic to the subject to which the composition is administered. The composition may be sterile.

[0025] As used herein, the terms "subject," "individual," and "patient" are used interchangeably. A subject can be an animal. In some embodiments, a subject is a mammal, such as a non-human animal (e.g., a cow, pig, horse, cat, dog, rat, mouse, monkey, or other primate, etc.). In some embodiments, a subject is a human.

[0026] As used in this disclosure and claims, the singular forms "a," "an," and "the" include the plural forms unless the context clearly dictates otherwise.

[0027] Whenever an embodiment is described herein with the word "comprising," it is understood that other similar embodiments described with the words "consisting of" and / or "consisting essentially of" are also provided. In this disclosure, "comprises," "comprising," "containing," and "having," etc., may mean "includes," "including," etc. "Consisting essentially of" or "consists essentially of" is open-ended and allows for the presence of more than what is recited, but excludes prior art embodiments, so long as the presence of more than what is recited does not alter basic or novel characteristics of what is recited.

[0028] Unless specifically stated or clear from the context, as used herein, the term "or" is understood to be inclusive. When used herein in a phrase such as "A and / or B," it is intended to include "A and B," "A or B," "A," and "B." Similarly, when used in a phrase such as "A, B, and / or C," it is intended to encompass each of the following aspects: A, B, and C; A, B, or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone).

[0029] coronavirus vaccine The recent Covid-19 pandemic has created an urgent need for improved vaccines targeting coronaviruses of concern. To date, several variants of SARS-CoV-2 have been identified, with some of the most infectious being the delta and omicron variants. All currently approved vaccines for the treatment of SARS-CoV-2 involve stimulating immunity to the SARS-CoV-2 spike protein. However, several mutations in the receptor-binding domain of the spike protein have been identified in new variants of SARS-CoV-2, which are thought to have led to increased vaccine resistance in these newly emerged variants (Zhao, J. et al., Environmental research, (2022), 206 (112240)). Studies estimate that current vaccines are approximately 3-5 times less effective against the delta variant of SARS-CoV-2 than the alpha variant (Planas, D. et al., Nature, (2021), 596, 276-280).

[0030] Thus, there is a continuing need for improved vaccines in general, including those useful for the prevention and treatment of coronaviruses.

[0031] Coronavirus virions contain multiple glycosylated spike (S) proteins that protrude from the surface of the virion. These S proteins form trimeric structures and mediate viral entry into host cells, making them prime targets for vaccine design.

[0032] The coronavirus spike protein is 1,273 amino acids long and contains a signal peptide and two subunits, S1 and S2. The S1 subunit contains a receptor-binding domain (RBD) that recognizes and binds to a specific host cell receptor, angiotensin-converting enzyme 2 (ACE2). The S2 subunit mediates virus-cell membrane fusion.

[0033] Thus, in one example, the nucleic acid molecule comprises a sequence encoding the S protein or an antigenic fragment thereof. Upon delivery to a host cell, the S protein is translated and processed in the host cell, resulting in the display of trimerized S protein on the host cell surface.

[0034] In some examples, the nucleic acid molecule comprises sequences encoding a CoV S protein and a ferritin protein, wherein the CoV S protein and ferritin assemble to form the nanoantigen particle.

[0035] The S protein may be in a prefusion conformation. Additionally, the S protein may contain K986P and / or V987P mutations, which stabilize the S protein in the prefusion conformation (Wrapp D et al. Science (2020), 367:1260-1263).

[0036] In one example, a nucleic acid molecule of the present disclosure encodes an antigenic fragment thereof that is a receptor binding domain (RBD).

[0037] The vaccines of the present disclosure include a nucleic acid molecule encoding a salvecoronavirus (SARS-CoV). The antigen may be an antigen described anywhere herein. In one example, the salvecoronavirus antigen may be selected from any SARS-CoV-2 antibody or immunogenic fragment thereof. In one example, the nucleic acid molecule is an mRNA sequence encoding a SARS-CoV-2 antigen selected from one or more of the following variants: Wuhan, alpha, beta, delta, and omicron, and optionally selected from subvariants BA.1, BA.2, BA.2.86, BA.3, BA.4 / 5, BQ.1, BQ.1.1, JN.1, XBB.1, and XBB.1.5. In one example, the nucleic acid molecule is an mRNA sequence encoding a SARS-CoV-2 spike (S) protein or an immunogenic fragment thereof selected from one or more of the following variants: Wuhan, alpha, beta, delta, and omicron, and optionally selected from subvariants BA.1, BA.2, BA.2.86, BA.3, BA.4 / 5, BQ.1, BQ.1.1, JN.1, XBB.1, and XBB.1.5.

[0038] The vaccine further comprises a nucleic acid sequence encoding a multimerization unit. In one example, the multimerization unit is a ferritin protein. The multimerization unit can be a scaffold for an antigen particle. In some examples, the ferritin is Helicobacter pylori ferritin. In some examples, the nucleic acid sequence encoding the ferritin can be modified to remove native glycosylation sites. In some examples, the nucleic acid molecule comprises sequences encoding an antigen protein and a ferritin protein, and the antigen protein and ferritin assemble to form a nanoantigen particle.

[0039] Vaccines according to the present disclosure further comprise a sequence encoding a linker, which may be encoded between the antigen and the multimerization unit, optionally the ferritin protein, such that the antigen is fused to the multimerization unit in the encoded molecule.

[0040] In one example, the vaccine comprises RNA 5'- and 3'-UTR sequences and an mRNA coding sequence.

[0041] Polymerization Unit The vaccines described herein include nucleic acid molecules encoding fusion proteins comprising a vaccine antigen linked to a multimerization unit. In some examples, such multimerization units confer desired properties to the antigen encoded by the nucleic acid molecule. For example, the Examples show that multimerization units improve the immunogenicity of an antigen (e.g., COVID spike protein) compared to the immunogenicity of the same antigen expressed without the multimerization unit. Furthermore, the multimerization units provided herein improve pan-variant responses to the antigen. For example, nucleic acid molecules provided herein comprising a coding sequence encoding a COVID spike protein-multimerization unit fusion protein elicit a broader immune response to SARs-CoV-2 variants when administered as a booster vaccine compared to the spike protein alone.

[0042] In some examples, the multimerization unit is a protein that can self-assemble into highly symmetric, stable, and structurally organized protein nanoparticles with diameters of 10 to 150 nm, a size range well suited for optimal interaction with various cells of the immune system. In some examples, viral proteins or virus-like particles (VLPs) can be used to form stable nanoparticle structures. Examples of such viral proteins are known in the art. For example, in some examples, the multimerization unit is hepatitis B surface antigen (HBsAg). HBsAg forms spherical particles with an average diameter of approximately 22 nm, lacks nucleic acid, and is therefore non-infectious (Lopez-Sagaseta, J. et al. Computational and Structural Biotechnology Journal 14 (2016) 58-68). In some examples, the multimerization unit is hepatitis B core antigen (HBcAg), which self-assembles into particles with diameters of 24 to 31 nm, similar to viral cores obtained from HEY-infected human livers. The produced HBcAg self-assembles into two classes of nanoparticles of different sizes, with diameters of 300 A and 360 A, corresponding to 180 or 240 protomers. In some instances, an antigen is fused to HBsAG or HBcAG to promote self-assembly of antigen-presenting nanoparticles.

[0043] In some examples, the multimerization unit is selected from the following self-assembling proteins: ferritin, lumazine synthase, and encapsulin.

[0044] Ferritin is a protein whose primary function is intracellular iron storage. It consists of 24 subunits, each consisting of four alpha-helical bundles that self-assemble into a quaternary structure with octahedral symmetry (Cho KJ et al. J Mol Biol. 2009;390:83-98). Several high-resolution structures of ferritin have been determined. Helicobacter pylori ferritin is composed of 24 identical protomers, while animal ferritin light and heavy chains exist that can assemble independently or bind to particles of 24 subunits in different ratios (Granier T. et al. J Biol Inorg Chem. 2003;8:105-111; Lawson DM et al. Nature. 1991;349:541-544). Ferritin self-assembles into nanoparticles with robust thermal and chemical stability. Therefore, ferritin nanoparticles are well suited to carrying and exposing antigens.

[0045] Lumazine synthase (LS) is also highly suitable as a nanoparticle platform for antigen presentation. LS, responsible for the penultimate catalytic step in riboflavin biosynthesis, is an enzyme present in a wide variety of organisms, including archaea, bacteria, fungi, plants, and eubacteria (Weber, S.E.Flavins and Flavoproteins. Methods and Protocols, Series: Methods in Molecular Biology. 2014). LS monomers are 150 amino acids long and consist of a beta sheet flanked by tandem alpha helices. Numerous different quaternary structures have been reported for LS, showing morphological diversity ranging from a homopentamer to a symmetric assembly of 12 pentamers forming a capsid with a diameter of 150 Å. LS cages of over 100 subunits have even been described (Zhang, X. et al., J. Mol. Biol. 2006;362:753-770).

[0046] Encapsulin, a novel protein cage nanoparticle isolated from the thermophilic bacterium Thermotoga maritima, can also be used as a platform for presenting antigens on the surface of self-assembling nanoparticles. Encapsulin is assembled from 60 copies of identical 31 kDa monomers with a thin, icosahedral, T=1 symmetric cage structure, with inner and outer diameters of 20 nm and 24 nm, respectively (Sutter M. et al. Nat Struct Mol Biol. 2008, 15:939-947). The exact function of encapsulin in T. maritima is not yet clearly understood, but its crystal structure was recently elucidated and its function was hypothesized as a cellular compartment that encapsulates proteins such as DyP (dye decolorizing peroxidase) and Flp (ferritin-like protein) involved in the oxidative stress response (Rahmanpour R. et al. FEES J. 2013, 280:2097-2104).

[0047] Linker The vaccines disclosed herein may include a nucleic acid encoding a fusion protein. In such cases, each domain of the fusion protein (e.g., an antigen and a multimerization unit) may be separated by a coding sequence encoding a linker sequence. In some examples, the linker may be a glycine-serine linker.

[0048] In some examples, the glycine-serine linker has the following amino acid sequence: GSGGSG (SEQ ID NO: 4): In some examples, the glycine-serine linker is encoded by SEQ ID NO: 5.

[0049] Those of skill in the art will understand that other art-recognized linkers may be suitable for use in the constructs of the present disclosure (e.g., encoded by the nucleic acid molecules provided herein). Those of skill in the art will similarly understand that other polycistronic constructs (nucleic acid molecules encoding two or more antigens / polypeptides separately within the same molecule) may be suitable for use as provided herein.

[0050] In various examples, a vaccine according to the present disclosure includes, in the 5' to 3' direction of transcription, a promoter, 5'-UTR and 3'-UTR flanking the antigen coding sequence, and a polyadenylation signal.

[0051] In one example, the vaccines described herein further comprise a 5'-cap structure, optionally a cap1 structure. Further suitable cap structures and approaches for generating suitable cap structures are described in WO 2017 / 053297 and Tusup et al., "Design of in vitro Transcribed mRNA Vectors for Research and Therapy," Chim Int J Chem. 2019;73(5):391-394, both of which are incorporated herein by reference. 5'-capping of polynucleotides is completed simultaneously during the in vitro transcription reaction using the following chemical RNA cap analog to create a 5'-guanosine cap structure: 3'-O-Me-m7G(5')ppp(5')G [ARCA cap] according to the manufacturer's protocol. G(5')ppp(5')A; G(5')ppp(5')G; m7G(5')ppp(5')A; m7G(5')ppp(5')G (New England BioLabs, Ipswich, MA). 5'-capping of the modified RNA may be completed post-transcriptionally using vaccinia virus capping enzyme to generate the "Cap 0" structure: m7G(5')ppp(5')G (New England BioLabs, Ipswich, MA). Cap 1 structure may be generated using both vaccinia virus capping enzyme and 2'-O-methyltransferase to generate m7G(5')ppp(5')G-2'-O-methyl. Cap 2 structure may be generated from the Cap 1 structure, followed by 2'-O-methylation of the third nucleotide from the 5' end using 2'-O-methyltransferase. The Cap 3 structure may be generated from the Cap 2 structure, followed by 2'-O-methylation of the fourth nucleotide from the 5' end using a 2'-O-methyl-transferase. The enzyme may be derived from a recombinant source. Further suitable means for generating suitable cap structures are disclosed in WO 2016 / 193226, which is incorporated herein by reference.

[0052] In one example, a vaccine of the present disclosure includes a promoter that is any promoter for a DNA-dependent RNA polymerase, such as T7 (optionally comprising or consisting of the sequence TAATACGACTCACTATAAGG (SEQ ID NO: 15)), T3, SP6, or Syn5 RNA polymerase.

[0053] In some examples, the vaccines disclosed herein contain a polyadenylation signal (polyA tail). The polyA tail is a long sequence of adenine residues at the 3' end of the molecule. The polyA tail serves two purposes: it is essential for translation, and poly(A)-binding protein (PABP) recruits translation factors to enhance the level of translation. Furthermore, the polyA tail improves the stability of the nucleic acid molecule by binding poly(A) in the mRNA, protecting it from exonuclease digestion. In mRNA, the polyA tail is also known to play an important role in transporting mRNA from the nucleus to the ribosome (Shlake, T. et al., RNA Biol., (2012), 9(11), 1319-1330). In one example, a nucleic acid molecule of the present disclosure contains a polyA tail of about 50 to about 500 adenosine nucleotides. For example, the poly-A tail can contain 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300 adenosines. In some examples, the poly-A tail contains 50-250 adenosines. In some examples, the poly-A tail contains 60-100 adenosines. In some examples, the poly-A tail contains 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, or 80 adenosines. In some examples, the poly-A tail contains 77 adenosines. In some instances, the polyA tail contains 74 adenosines.

[0054] In one example of the present disclosure, the vaccine comprises a split poly(A) tail, which may include at least two adenosine-containing elements, optionally containing 30-60 adenosines each, optionally separated by a spacer of 1-25 nucleotides.

[0055] Leader sequence In some instances, the antigen-encoding sequences disclosed herein include a leader sequence. The leader sequence may encode a signal peptide. In some instances, the signal peptide is fused to the expressed therapeutic protein. In such instances, the leader sequence and the gene of interest are within the same open reading frame (ORF).

[0056] Signal peptides comprise the N-terminal 15–60 amino acids of a protein and are typically required for translocation across membranes along the secretory pathway, controlling the entry of most proteins into the secretory pathway. In eukaryotes, the signal peptide of a nascent precursor protein (preprotein) directs ribosomes to the rough endoplasmic reticulum (ER) and initiates transport of the growing peptide chain across it for processing. ER processing produces the mature protein, and the signal peptide, at least for secreted proteins, is typically cleaved by a resident signal peptidase.

[0057] The signal peptide may have a length of 15 to 60 amino acids. For example, the signal peptide may have a length of 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, or 60 amino acids. In some examples, the signal peptide may have a length of 20 to 60, 25 to 60, 30 to 60, 35 to 60, 40 to 60, 4 ... 60, 40-60, 45-60, 50-60, 55-60, 15-55, 20-55, 25-55, 30-55, 35-55, 40-55, 45-55, 50-55, 15-50, 20-50, 25-50, 30-50, 35-50, 40-50, 45-50, 15-45, 20-45 , 25-45, 30-45, 35-45, 40-45, 15-40, 20-40, 25-40, 30-40, 35-40, 15-35, 20-35, 25-35, 30-35, 15-30, 20-30, 25-30, 15-25, 20-25, or 15-20 amino acids in length. In some examples, the signal peptide has the following sequence: MPLLLLLPLLWAGALA (SEQ ID NO: 8).

[0058] Nucleosides and nucleotides In some examples, the vaccines provided herein comprise chemically unmodified nucleic acids (preferably mRNA) that contain the standard RNA nucleotides adenine (A), uracil (U), guanine (G), or cytosine (C).

[0059] In some examples, the vaccine comprises a nucleic acid comprising a modified nucleotide. Many modified nucleotides are known in the art, as disclosed in International Publication No. WO 2007 / 024708, which is incorporated herein by reference. The modifications can include either naturally occurring or non-naturally occurring modifications. The modifications can include those in the sugar, backbone, or nucleobase protein of the nucleotide and / or nucleoside, as is well known in the art.

[0060] In some examples, the nucleic acid molecules herein can include natural (i.e., standard) nucleotides or nucleosides, non-natural or naturally occurring modified nucleotides or nucleosides, or any combination thereof.

[0061] In one example, the RNA can include standard A, G, and C nucleotides as well as modified U nucleotides.

[0062] In some instances, nucleic acid molecules comprising modified nucleosides or nucleotides (e.g., "modified RNA nucleic acid molecules") exhibit reduced immunogenicity in a cell or organism compared to an unmodified RNA nucleic acid molecule comprising the same sequence.

[0063] In some examples, modified nucleosides provided herein (e.g., RNA nucleic acid molecules such as mRNA) include N1-methyl-pseudouridine (m1Ψ), 1-ethyl-pseudouridine (e1Ψ), 5-methoxy-uridine (mo5U), 5-methyl-cytidine (m5C), and / or pseudouridine (Ψ). In some examples, modified nucleotides in a nucleic acid molecule (e.g., RNA nucleic acid molecule such as mRNA) include 5-methoxymethyluridine, 5-methylthiouridine, 1-methoxymethylpseudouridine, 5-methylcytidine, and / or 5-methoxycytidine. In some examples, an RNA nucleic acid molecule includes a combination of at least two (e.g., two, three, four, or more) of any of the foregoing modified nucleobases.

[0064] In some examples, the nucleic acid molecules provided herein contain N1-methyl-pseudouridine (m1Ψ) at one or more or all uridine positions of the nucleic acid molecule.

[0065] In some examples, the nucleic acid molecule comprises 5-methoxy-uridine (mo5U) at one or more or all uridine positions of the nucleic acid molecule.

[0066] In some examples, a nucleic acid molecule contains from about 1% to about 100% modified nucleotides (either with respect to overall nucleotide content or with respect to one or more types of nucleotides (i.e., any one or more of A, G, U, T, or C)). In some examples, a nucleic acid molecule contains any intervening percentage of modified nucleotide content, e.g., 1% to 20%, 1% to 25%, 1% to 50%, 1% to 60%, 1% to 70%, 1% to 80%, 1% to 90%, 1% to 95%, 10% to 20%, 10% to 25%, 10% to 50%, 10% to 60%, 10% to 70%, 10% to 80%, 10% to 90%, 10% to 95%, 10% to 100%, 20% to 25%, 20% to 50%, 20% to 60%, 20% to 70%, 20% ~80%, 20%-90%, 20%-95%, 20%-100%, 50%-60%, 50%-70%, 50%-80%, 50%-90%, 50%-95%, 50%-100%, 70%-80%, 70%-90%, 70%-95%, 70%-100%, 80%-90%, 80%-95%, 80%-100%, 90%-95%, 90%-100%, and 95%-100%. The remaining percentages are made up of unmodified A, G, U, T, or C.

[0067] A nucleic acid molecule can contain as little as 1% and as much as 100% modified nucleotides, or any intervening percentage, e.g., 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, a nucleic acid can contain modified pyrimidines such as modified uracil or cytosine. In some examples, at least 5%, at least 10%, at least 25%, at least 50%, at least 80%, at least 90%, or 100% of the uracils in a nucleic acid are substituted with modified uracils (e.g., 5-substituted uracils). The modified uracils can be substituted with a compound having a single unique structure, or with multiple compounds having different structures (e.g., two, three, four, or more unique structures). In some examples, at least 5%, at least 10%, at least 25%, at least 50%, at least 80%, at least 90%, or 100% of the cytosines in the nucleic acid are substituted with modified cytosines (e.g., 5-substituted cytosines). The modified cytosines can be substituted with a compound having a single unique structure or with multiple compounds having different structures (e.g., two, three, four, or more unique structures).

[0068] In some examples, the nucleic acid molecule is an mRNA in which uridines are replaced by compounds having a single unique structure. In some examples, the single unique structure is N1-methyl-pseudouridine. In some examples, the nucleic acid molecule contains at least 5%, at least 10%, at least 25%, at least 50%, at least 80%, at least 90%, or 100% N1-methyl-pseudouridine.

[0069] In one example, the mRNA comprises modified nucleobases. In some examples, the modified nucleobases are modified adenine (A), cytosine (C), uracil (U), and guanine (G).

[0070] In one example, the modified nucleobase is a modified U. In some examples, the modified U is 1-methylpseudouridine (m1Ψ) and pseudouridine (Ψ), as disclosed in WO 2007 / 024708, which is incorporated herein by reference.

[0071] In one example, a nucleic acid molecule of the present disclosure comprises a UTR sequence that includes 5-methoxy-uridine (mo5U) at one or more or all uridine positions of the nucleic acid molecule. The molecule can include a ratio of at least 25% modified to unmodified uridines, including 25%-50%, or at least 50%.

[0072] The examples show that modification of uridines in the 5'-UTR sequence derived from the human CHIT1 5'-UTR and the 3'-UTR sequence derived from the human citrate synthase (CS) 3'-UTR results in a particularly substantial increase in translation.

[0073] In one example, a nucleic acid molecule of the present disclosure comprises a sequence that includes N1-methyl-pseudouridine (m1Ψ) at one or more or all uridine positions of the nucleic acid molecule. The molecule can contain at least a 75% ratio of modified uridines to unmodified uridines, including 100%.

[0074] manufacturing The vaccines of the present disclosure can be produced by in vitro transcription. In vitro transcription of RNA is known in the art and is described in International Publication No. 2014 / 152027, the entire contents of which are incorporated herein by reference. In some examples, the RNA of the present disclosure is prepared according to any one or more of the methods described in International Publication Nos. 2018 / 053209 and 2019 / 036682, each of which is incorporated herein by reference. In summary, a DNA template is typically generated as a linearized plasmid, and then in vitro transcription to synthesize RNA is performed in parallel with or after capping.

[0075] The 5' cap can be added by a multi-step enzymatic reaction or via co-transcription. In co-transcriptional capping, a cap analog such as CleanCap® AG is added directly to the in vitro transcription mixture. Alternatively, enzymatic capping using vaccinia virus capping enzyme is performed separately from in vitro transcription.

[0076] After purification, the mRNA product can be encapsulated in lipid nanoparticles (LNPs).

[0077] composition The present disclosure also provides a pharmaceutical composition comprising a nucleic acid molecule or LNP as defined anywhere herein and a pharmaceutical carrier.

[0078] The present disclosure further provides a composition comprising a first nucleic acid molecule according to the present disclosure, wherein the disease-associated antigen is a delta variant S protein. In one example, the disease-associated antigen of the first nucleic acid molecule is a Wuhan variant S protein.

[0079] In one example, a composition according to the present disclosure may further comprise a second nucleic acid molecule encoding an Omicron strain S protein, optionally mutant BA.1, BA.2, BA.2.86, BA.3, BA.4 / 5, BQ.1, BQ.1.1, JN.1, XBB.1, or XBB.1.5.

[0080] In one example, the second nucleic acid molecule encodes the omicron mutant S protein BA.4 / 5.

[0081] In one example, the second nucleic acid molecule encodes the omicron mutant S protein XBB.1.5.

[0082] In all examples of this disclosure, the antigen-encoding sequence can be further optimized via mutation to improve protein stability (such as the structure of the CoV spike protein or RBD), maximize protein translation, and reduce unwanted side effects.

[0083] In some examples of the present disclosure, the antigen-encoding sequence may be optimized via mutation to increase the stability of the trimerized S protein and / or to remove the furin cleavage site.

[0084] In some examples of the present disclosure, the disease-associated antigen is an antigenic fragment of the CoV S protein consisting of amino acid residues 1 to 1162 of the CoV S protein.

[0085] The composition can include an effective amount of a nucleic acid molecule as defined herein. The effective amount of a nucleic acid molecule used therapeutically will depend, for example, on the therapeutic objectives, the route of administration, and the condition of the patient. In one example, an effective amount of a nucleic acid molecule as defined anywhere herein in a pharmaceutical composition is effective to treat or prevent a disease associated with a coronavirus infection.

[0086] The composition is a pharmaceutically acceptable (e.g., physiologically acceptable) composition and includes a carrier, preferably a pharmaceutically acceptable (e.g., physiologically acceptable) carrier. A pharmaceutically acceptable carrier may include one or more excipients. Pharmaceutically acceptable excipients are known and include carriers, excipients, or stabilizers that are non-toxic to cells or mammals exposed thereto at the dosages and concentrations used. Any suitable carrier can be used within the context of the present disclosure, and such carriers are well known in the art. The choice of carrier will be determined, in part, by the particular site to which the composition may be administered and the particular method used to administer the composition. The physiologically acceptable excipient may be a pH-buffered aqueous solution. Examples of physiologically acceptable excipients include buffers, such as phosphate, citrate, and other organic acids; antioxidants, including ascorbic acid; low molecular weight (less than about 10 residues) polypeptides; proteins, such as serum albumin, gelatin, immunoglobulins; hydrophilic polymers, such as polyvinylpyrrolidone; amino acids, such as glycine, glutamine, asparagine, arginine, or lysine; monosaccharides, disaccharides, and other carbohydrates, including glucose, mannose, or dextrins; chelating agents, such as ethylenediaminetetraacetic acid (EDTA); sugar alcohols, such as mannitol and sorbitol; salt-forming counterions, such as sodium; and / or non-ionic surfactants, such as TWEEN™, polyethylene glycol (PEG), and PLURONICS™.

[0087] The composition can be optionally sterilized. The composition can be frozen or lyophilized for storage and reconstituted in a suitable sterile carrier before use. The composition can be produced according to conventional techniques, for example, as described in Remington: The Science and Practice of Pharmacy, 21st Edition, Lippincott Williams & Wilkins, Philadelphia, PA (2001).

[0088] The compositions may be administered intravenously. The compositions may also be administered parenterally or subcutaneously.

[0089] Methods of administering the pharmaceutical compositions defined herein include, but are not limited to, parenteral administration (e.g., intradermal, intramuscular, intraperitoneal, intravenous, and subcutaneous), epidural, and mucosal (e.g., intranasal and oral routes). In particular examples, the pharmaceutical compositions are administered intranasally, intramuscularly, intravenously, or subcutaneously. The compositions may be administered by any convenient route, for example, by infusion or bolus injection, by absorption through epithelial or mucocutaneous linings (e.g., oral mucosa, intranasal mucosa, rectal and intestinal mucosa, etc.), and may be administered together with other biologically active agents. Administration may be systemic or local. Each dose may or may not be administered by the same route of administration.

[0090] Delivery System Various delivery systems are known and can be used to administer prophylactic or therapeutic agents (e.g., nucleic acid molecules disclosed herein), including, but not limited to, encapsulation in liposomes, microparticles, microcapsules, construction of nucleic acids as part of retroviruses or other vectors, etc. In addition, pulmonary administration can also be used, e.g., by use of an inhaler or nebulizer and formulation with an aerosolizing agent.

[0091] The present disclosure relates to nucleic acid molecules that may be suitable for use as vaccine vectors.

[0092] Lipid nanoparticles (LNPs) may be used as a platform for vaccine vector delivery. LNPs may contain ionizable cationic lipids, cholesterol, phospholipids (such as distearoylphosphatidylcholine), and polyethylene glycol (PEG)-lipids. The ionizable cationic lipids are involved in nanoparticle packaging by interacting with negatively charged RNA molecules. Upon administration, LNPs are rapidly cleared from injected tissues and are therefore unlikely to induce inflammation and tissue damage.

[0093] Therefore, in one example of the present disclosure, the nucleic acid molecule described anywhere herein is packaged in a delivery system. In one example, the delivery system is an LNP. Thus, the present disclosure also relates to an LNP comprising the nucleic acid molecule described anywhere herein.

[0094] In one example, the LNP comprises a nucleic acid molecule described anywhere herein, where the nucleic acid molecule encodes an antigenic protein. In one example, the LNP comprises one or more nucleic acid molecules described anywhere herein, where the molecule encodes a CoV S protein.

[0095] Uses of vaccine compositions After administration to a patient, the coding sequence is transcribed and translated, if it is a DNA sequence, or translated, if it is an RNA sequence, into the antigenic protein or fragment of the antigenic protein it encodes. The production of these antigenic proteins or fragments of antigenic proteins stimulates an immune response, resulting in the production of neutralizing antibodies. Upon infection with the corresponding infectious agent, the presence of neutralizing antibodies and memory B cells increases the rate of the immune response and minimizes the severity and duration of the onset of symptoms.

[0096] The vaccine vectors of the present disclosure may be used as prophylactic treatments against disease-causing target antigens. In one example of the present disclosure, the vaccine vectors may be used to prevent CoV, particularly SARS-CoV-2.

[0097] The vaccine vectors of the present disclosure may also be used as treatments against target antigens that have infected a subject. In one example of the present disclosure, the vaccine vectors may be used to treat CoV, particularly SARS-CoV-2.

[0098] Methods for inducing immune responses to pan-salveolar coronavirus mutants According to a first aspect, the present disclosure provides a method for inducing a pan-salvecoronavirus variant immune response in an individual who has previously received one or more doses of a first SARS-CoV-2 vaccine against one or more first salvecoronavirus variants (variant 1), the method comprising administering to the individual one or more doses of a second SARS-CoV-2 vaccine, wherein the second SARS-CoV-2 vaccine comprises mRNA encoding a single spike (S) protein or an immunogenic fragment or immunogenic variant thereof from a salvecoronavirus variant (variant 2) different from variant 1, wherein the S protein is encoded as an S protein-multimerization subunit fusion, and the method induces a pan-variant immune response against salvecoronavirus variant 1 and variant 2 in the individual, and induces an immune response against one or more additional salvecoronavirus variants different from variant 1 and variant 2.

[0099] The phrase "pan-salvecoronavirus immune response" refers to an immune response generated in response to challenge with multiple salvecoronavirus variants. In a preferred example, the salvecoronavirus variants are SARS-Cov-2 variants, including but not limited to Wuhan D614G, alpha, beta, delta, and omicron, and optionally subvariants BA.1, BA.2, BA.2.86, BA.3, BA.4 / 5, BQ.1, BQ.1.1, JN.1, XBB.1, and XBB.1.5.

[0100] In one example, variant 2 is SARS-CoV-2 Omicron BA.4 / 5. In one example, variant 2 is SARS-CoV-2 Omicron XBB.1.5. In one example, variant 1 is SARS-CoV-2 Wuhan D614G. In one example, variant 1 is SARS-CoV-2 Delta.

[0101] In one example, the method induces an immune response against one or more additional salvecoronavirus variants that are mutationally distinct from variant 1 and / or variant 2. As used herein, the term "mutationally distinct" refers to SARS-CoV-2 variants that have distinct and distinct mutation lineages. For example, mutationally distinct SARS-CoV-2 variants may be named according to the Pango phylogenetic nomenclature. Pango lineages are designated to aid in fine-scale tracking of SARS-CoV-2. They represent clades within a phylogenetic tree defined by both at least one evolutionary event (nonsynonymous mutation, insertion / deletion, or recombination event) and an epidemiologically significant event.

[0102] In one example, the immune response is a neutralization response determined by the presence of neutralizing antibodies (Nab). Methods for detecting the presence of Nab in a sample obtained from an individual (e.g., microneutralization assays, enzyme-linked immunosorbent assays (ELISAs), and rapid lateral flow assays) are apparent to those skilled in the art, and any suitable method can be used. Kuan-Ting Lui et al. (Viruses (2022) 14 (7) 1560) provides an overview of international standards for detecting SARS-CoV-2 neutralizing antibodies, the contents of which are incorporated herein in their entirety.

[0103] The immune response is preferably a protective immune response, meaning that the immune response provides the individual with protection against infection or disease caused by the SARS-CoV-2 variant. Protection can mean that the individual does not suffer from any symptoms of infection, or that any symptoms of infection experienced after vaccination are less severe or shorter lasting than those experienced without vaccination.

[0104] Preferably, the individual is a human, and may be an infant, child, adolescent, or adult.

[0105] The multimerization unit may be selected from the following self-assembling proteins: ferritin, lumazine synthase, and encapsulin. In a preferred example, the protein multimerization subunit fusion is an S protein-ferritin subunit fusion.

[0106] In one example, the second SARS-CoV-2 vaccine comprises an additional monovalent immunogenic composition comprising mRNA encoding a single spike (S) protein or an immunogenic fragment or immunogenic variant thereof, wherein the S protein is encoded as an S protein-multimerized subunit fusion and is different from variant 2 and is derived from the same or a different salve coronavirus variant as variant 1.

[0107] In one example, the second SARS-CoV-2 vaccine comprises mRNA formulated in lipid nanoparticles (LNPs).

[0108] In one example, the second SARS-CoV-2 vaccine comprises the mRNA sequence of SEQ ID NO: 11.

[0109] In one example, the second SARS-CoV-2 vaccine comprises the mRNA sequence of SEQ ID NO: 17.

[0110] In one example, the first SARS-CoV-2 vaccine includes a protein antigen that is not provided in the form of a virus-like particle (VLP). In this example, the first SARS-CoV-2 vaccine does not include a nucleic acid encoding a salve coronavirus S protein in the form of a fusion protein that can assemble in vivo to form nanoparticles. As used herein, "first" generally refers to a previous SARS-CoV-2 vaccine that is compositionally distinct from the compositions disclosed herein. In other words, the present invention describes a previous vaccine that encodes or delivers an S protein antigen or an immunogenic fragment or variant thereof. Depending on the vaccination status of the subject, this can refer to a prime vaccine or a subsequent boost vaccine administered prior to the "second" vaccine disclosed herein.

[0111] In one example, the second SARS-CoV-2 vaccine is a monovalent vaccine, meaning that the vaccine composition administered to the vaccinated individual comprises mRNA encoding a single spike (S) protein antigen, or an immunogenic fragment or immunogenic variant thereof.

[0112] In an alternative example, the second SARS-CoV-2 vaccine is a bivalent vaccine comprising an additional mRNA encoding a single spike (S) protein or immunogenic fragment or immunogenic variant thereof, wherein the S protein is encoded as an S protein-multimerized subunit fusion and is distinct from variant 2 and is derived from the same or a different salvecoronavirus variant as variant 1. In some examples, the additional mRNA of the second SARS-CoV2 vaccine comprises the mRNA sequence of SEQ ID NO: 9 or SEQ ID NO: 10.

[0113] One or more doses of each of the first and second SARS-CoV-2 vaccines may be administered to an individual as needed as part of an approved prime-boost vaccination regimen. In one example, the first dose of the second SARS-CoV-2 vaccine is administered to an individual at least four months after the administration of the final dose of the first SARS-CoV-2 vaccine. In a further example, the first dose of the second SARS-CoV-2 vaccine is administered to an individual at least six months after the administration of the final dose of the first SARS-CoV-2 vaccine.

[0114] A second aspect of the present disclosure provides an immunogenic composition comprising mRNA encoding a single spike (S) protein or an immunogenic fragment or immunogenic variant thereof from a first salvecoronavirus variant for use in inducing a pan-salvecoronavirus variant immune response in an individual who has previously received one or more doses of a first SARS-CoV-2 vaccine comprising or encoding an immunogen from a second salvecoronavirus variant, wherein the S protein is encoded as an S protein-multimerization subunit fusion, and the immunogenic composition is used to induce an immune response against the first and second salvecoronavirus variants and against at least a third salvecoronavirus variant.

[0115] The phrase "pan-salvecoronavirus immune response" refers to an immune response generated in response to challenge with multiple salvecoronavirus variants. In one example, the salvecoronavirus variants are SARS-Cov-2 variants, including but not limited to Wuhan D614G, alpha, beta, delta, and omicron, optionally BA.1, BA.2, BA.2.86, BA.3, BA.4 / 5, BQ.1, BQ.1.1, JN.1, XBB.1, and XBB.1.5.

[0116] In one example, the first salvecoronavirus variant is SARS-CoV-2 Omicron BA.4 / 5. In one example, the first salvecoronavirus variant is SARS-CoV-2 Omicron XBB.1.5. In one example, the second variant is SARS-CoV-2 Wuhan D614G. In one example, variant 1 is SARS-CoV-2 Delta.

[0117] Preferably, the third salvecoronavirus variant is mutationally distinct from the first salvecoronavirus variant and / or the second salvecoronavirus variant. As used herein, the term "mutationally distinct" refers to SARS-CoV-2 variants that have distinct and distinct mutational lineages. For example, mutationally distinct SARS-CoV-2 variants may be named according to the Pango phylogenetic nomenclature. Pango lineages are designated to aid in fine-scale tracking of SARS-CoV-2. They represent clades within a phylogenetic tree defined by both at least one evolutionary event (nonsynonymous mutation, insertion / deletion, or recombination event) and an epidemiologically significant event.

[0118] In one example, the immune response is a neutralization response determined by the presence of neutralizing antibodies (Nab). Methods for detecting the presence of Nab in a sample obtained from an individual (e.g., microneutralization assays, enzyme-linked immunosorbent assays (ELISAs), and rapid lateral flow assays) are apparent to those skilled in the art, and any suitable method can be used. Kuan-Ting Lui et al. (Viruses (2022) 14 (7) 1560) provides an overview of international standards for detecting SARS-CoV-2 neutralizing antibodies, the contents of which are incorporated herein in their entirety.

[0119] The immune response is preferably a protective immune response, meaning that the immune response provides the individual with protection against infection or disease caused by the SARS-CoV-2 variant. Protection can mean that the individual does not suffer from any symptoms of infection, or that any symptoms of infection experienced after vaccination are less severe or shorter lasting than those experienced without vaccination.

[0120] Preferably, the individual is a human, and may be an infant, child, adolescent, or adult.

[0121] In one example, the S protein-multimerization subunit fusion is a protein-ferritin subunit fusion.

[0122] In one example, the mRNA is formulated in lipid nanoparticles (LNPs).

[0123] In another example, the mRNA comprises or consists of the mRNA sequence of SEQ ID NO:11.

[0124] In another example, the mRNA comprises or consists of the mRNA sequence of SEQ ID NO:17.

[0125] In another example, the first SARS-CoV-2 vaccine includes a protein antigen that is not provided in the form of a virus-like particle (VLP). In this example, the first SARS-CoV-2 vaccine does not include a nucleic acid encoding a salvecoronavirus S protein in the form of a fusion protein that can assemble in vivo to form a nanoparticle.

[0126] In one example, the immunogenic composition is a monovalent composition, meaning that it comprises mRNA encoding a single spike (S) protein antigen, or an immunogenic fragment or immunogenic variant thereof.

[0127] In an alternative example, the immunogenic composition is a bivalent composition comprising an additional mRNA encoding a single spike (S) protein or immunogenic fragment or variant thereof, wherein the S protein is encoded as an S protein-multimerization subunit fusion and is different from the first salvecoronavirus variant and is derived from a salvecoronavirus variant that is the same as or different from the second salvecoronavirus variant. In some examples, the additional mRNA of the bivalent composition comprises the mRNA sequence of SEQ ID NO:9 or SEQ ID NO:10. [Example]

[0128] The following examples further illustrate the present disclosure, but should not be construed as in any way limiting its scope.

[0129] Example 1 - Efficacy of mRNA vaccine vectors containing antigen-linker-ferritin sequences The overall objective of this study was to determine the immunogenicity in mice of a candidate SARS-CoV-2 mRNA vaccine that encoded a stabilized spike (S) protein-ferritin subunit fusion protein that, upon expression, assembled into nanoparticles for high-density antigen presentation.

[0130] method Mouse study 1 Groups of naive BALB / c mice (n=6 per group) were administered two 50μl injections of the LNP-formulated mRNA vaccine encoding the Wuhan D614G spike protein intramuscularly in the thigh muscle, 28 days apart. Approximately 150 days later, serum was collected and assessed for neutralizing antibody levels against the BA.4 / 5 variant using a SARS-CoV-2 pseudovirus-based neutralization assay (Figure 1a).

[0131] Approximately 200 days later, mice received a third immunization with an LNP-formulated mRNA vaccine encoding the nanoparticles disclosed herein. 14 days later, serum was collected and assessed for neutralizing antibody levels against a panel of SARS-CoV-2 mutants using a SARS-CoV-2 pseudovirus-based neutralization assay (Figure 1b).

[0132] At day 200, mice were divided into four groups and administered one or two mRNAs encoding antigens as specified in Table 1 below. Groups 1 and 4 received a bivalent vaccine encoding both the Wuhan ancestral and BA.4 / 5 spike (S) proteins. Group 4's vaccine encoded the antigen as a ferritin-linker fusion protein (virus-like particle, or nanoparticle, or "VLP"). Alternatively, groups 2 and 3 received vaccines encoding monovalent antigens, both as VLPs (group 2—Wuhan S protein; group 3—BA.4 / 5 S protein).

[0133] [Table 1]

[0134] Mouse study 2 Groups of naive BALB / c mice (n=6 per group) were administered the LNP-formulated mRNA vaccine encoding the Wuhan D614G spike protein intramuscularly in the thigh muscle as two 50 μl injections, 28 days apart.

[0135] Approximately 300 days later, the mice were divided into three groups: Group 1 received PBS, Group 2 received a monovalent vaccine encoding the Omicron XBB.1.5 spike protein, and Group 3 received a monovalent vaccine encoding the Omicron XBB.1.5 spike protein formatted as a VLP.

[0136] After 14 days, serum was collected and assessed for neutralizing antibody levels against a panel of SARS-CoV-2 mutants using a SARS-CoV-2 pseudovirus-based neutralization assay (Fig. 1c).

[0137] result Mouse studies modeling boost vaccination campaigns1 showed that VLP-based vaccines from groups 3 and 4 were more able to overcome the antigenic challenge experienced by mice administered the group 1 vaccine, with neutralizing antibody responses dominated by the ancestral variant (e.g., Wuhan "D614G") used as the inoculum in the original "prime" vaccination campaign. This is likely due to the fact that mice were originally challenged with the Wuhan D614G S protein in the initial vaccination campaign, and therefore recall of the antibody pool neutralizing this S protein dominates the group 1 vaccine response.

[0138] Mice in groups 1 (and 2) exhibit minimal neutralizing responses to BA.4 / 5 (Figure 1b), despite the fact that animals in group 1 were challenged with mRNA encoding the BA.4 / 5S protein. In contrast, vaccinated mice in groups 3 and 4 exhibit a 14-fold and 23-fold increase in mean neutralizing responses to BA4 / 5 compared to mice in group 1. Furthermore, mice in groups 3 and 4 also exhibit low-level neutralizing responses to the emerging variant of concern, BQ.1.1, whereas no responses to this variant are detected in mice in groups 1 or 2.

[0139] Similar results were obtained in mouse study 2, with mice in group 3 showing a 5.2-fold increase in mean neutralizing response to BA.4 / 5, a 2.7-fold increase in mean neutralizing response to XBB.1.5, and a 2.9-fold increase in mean neutralizing response to XBB.1.16 compared to mice in group 2.

[0140] Thus, overall, the data suggest that when mRNA is used to deliver VLP antigens, a broad neutralizing response can be obtained from a single vaccine construct, which may result in better efficacy against multiple existing and likely future variants of concern, without the need to independently generate boosters each time a new dominant variant emerges.

[0141] Example 2 - Immunogenicity of mRNA vaccine vectors containing antigen-linker-ferritin sequences in non-human primates The overall objective of this study was to determine the immunogenicity of candidate SARS-CoV-2 mRNA vaccines in non-human primates (NHPs).

[0142] method SARS-CoV-2 seronegative NHPs were immunized with two 10 μg doses (4 weeks apart) of either the mRNA-native delta vaccine or the mRNA-VLP delta vaccine. Neutralizing antibody titers were measured 2 weeks (day 42) after the second immunization against a panel of SARS-CoV-2 reporter viruses (ancestral D614G, delta, BA.1, BA.2, or BA.4 / 5) and approximately 6.5 months after the first immunization against the delta reporter virus. The frequency of long-lived antibody-secreting cells in bone marrow biopsies of vaccinated NHPs was measured using a B-cell ELISpot assay with recombinant delta antigen.

[0143] result Two weeks after the second immunization, the mRNA-VLP delta vaccine elicited neutralizing antibodies against the D614G, delta, BA.1, BA.2, or BA.4 / 5 reporter viruses with geometric mean titers (GMTs) that were 15-fold, 9-fold, 29-fold, 18-fold, and 7-fold higher, respectively, than those elicited by the mRNA-native delta vaccine (all p≦0.002; Figure 3). Furthermore, 196 days after the first dose, neutralizing antibody titers were 3.5-fold higher with the mRNA-VLP delta vaccine compared with the mRNA-native delta vaccine (GMTs of 236 and 68, respectively; Figure 4). The mRNA-VLP delta vaccine also induced a statistically significant 2-fold increase in long-lived antibody-secreting cells compared with the mRNA-native delta vaccine (10 6 16.9 vs. 8.8 per bone marrow cell, Figure 5).

[0144] Overall, the data confirm that broad neutralizing responses can be obtained from a single vaccine construct when mRNA is used to deliver VLP antigens, as observed in Example 1. The data also demonstrate that the mRNA-VLP delta vaccine elicits stronger and broader neutralizing antibody responses in NHPs compared to the mRNA-native delta vaccine. Additionally, the mRNA-VLP delta vaccine maintained higher neutralizing antibody titers over 6 months and generated more long-lived antibody-secreting cells compared to the mRNA-native delta vaccine.

[0145] Example 3 - Boosting Potential of mRNA Vaccine Vectors Containing Antigen-Linker-Ferritin Sequences in Vaccinated Non-Human Primates The overall objective of this study was to determine the boosting potential of a candidate SARS-CoV-2 mRNA vaccine in vaccine-experienced non-human primates (NHPs).

[0146] method NHPs were initially immunized with two doses (3 weeks apart) of the mRNA native ancestral Wuhan_D614G vaccine to establish baseline anti-spike immunity. Animals were then rested for approximately 7.5 months, at which point they received a third booster vaccination with either mRNA-native XBB.1.5 or mRNA-VLP XBB.1.5 (Figure 8). Neutralizing antibody titers were measured immediately before (day 246) and 14 days after (day 260) the third booster immunization against a panel of SARS-CoV-2 reporter viruses (ancestral Wuhan_D614G, Omicron BA.4 / 5, and Omicron XBB.1.5).

[0147] result Two weeks after the third immunization, a 30 μg dose of the mRNA-VLP XBB.1.5 vaccine elicited neutralizing antibodies against the D614G, BA.4 / 5, and XBB.1.5 reporter viruses with geometric mean titers (GMTs) comparable to those induced by a 30 μg dose of the mRNA-native XBB.1.5 vaccine (Figures 9-12). Furthermore, animals immunized with either 10 or 5 μg of the mRNA-VLP XBB.1.5 vaccine elicited neutralizing antibody titers comparable to those induced by a 30 μg dose of the mRNA-native XBB.1.5 or mRNA-VLP XBB.1.5 vaccine (Figures 9-12).

[0148] Overall, the data confirm that when mRNA is used to deliver VLP antigens, a broadly neutralizing response can be achieved with a single, low booster dose of an mRNA-VLP vaccine.

[0149] array SARS-CoV-2 Wuhan D614G spike protein-linker-ferritin RNA sequence (SEQ ID NO: 1)

[0150] SARS-CoV-2 delta-linker-ferritin RNA sequence (SEQ ID NO: 2)

[0151] SARS-CoV-2 Omicron BA.4 / 5-Linker-Ferritin RNA Sequence (SEQ ID NO: 3)

[0152] Linker amino acid sequence: GSGGSG (SEQ ID NO: 4).

[0153] Linker RNA sequence: GGUUCAGGUGGAUCAGGU (SEQ ID NO: 5)

[0154] Ferritin subunit, RNA sequence (SEQ ID NO: 6): GAUAUAGAAAAACUCCUCAAUGAACAAGUAAAUAAGGAGAUGCAAAGUUCUAACCUGUACAUGAGCAUGUCUUCUUGGUGUUACACCCAUAGCCUCGAUGGAGCGGGAUUGUUCCUUUUUGA CCACGCUGCGGAGGAGUAUGAGCAUGCUAAAAAGCUGAUAAUUUUCUCAACGAGAAUAAUGUUCCAGUGCAAUUGACAAGUAUAUCCGCCCCUGAGCAUAAGUUUGAAGGGCUCACACAAA UUUUCCAAAAGGCAUACGAACACGAACAGCACAUUAGCGAGUCUAUUAACAACAUUGUUGAUCAUGCAAUCAAGUCCAAAGAUCACGCCACGUUUAAUUUCCUCCAGUGGUAUGUAGCUGAG CAACAUGAGGAAGAAGUGUGUUUAAGGAUAUUCUUGAUAAAAUUGAACUUAUUGGAAAUGAGAACCAUGGCCUCUAUCUUGCGGACCAAUACGUCAAGGGAAUUGCCAAGUCCCGCAAGAGU

[0155] Ferritin subunit, protein sequence (SEQ ID NO: 7) DIEKLLNEQVNKEMQSSNLYMSMSSWCYTHSLDGAGLFLFDHAAEEYEHAKKLIIFLNENNVPVQLTSISAPEHKFEGLTQIFQKAYEHEQHISESINNIVDHAIKSKDHATFNFLQWYVAEQHEEEVLFKDILDKIELIGNENHGLYLADQYVKGIAKSRKS

[0156] Leader sequence: MPLLLLLPLLWAGALA (SEQ ID NO: 8).

[0157] mRNA construct sequence encoding SARS-CoV-2 Wuhan D614G spike-ferritin fusion protein (SEQ ID NO: 9)

[0158] mRNA construct sequence encoding SARS-CoV-2 deltaspike-ferritin fusion protein (SEQ ID NO: 10)

[0159] mRNA construct sequence encoding SARS-CoV-2 omicron BA.4 / 5 spike-ferritin fusion protein (SEQ ID NO: 11)

[0160] SARS-CoV2 Wuhan D614G spike-ferritin fusion protein polypeptide sequence (SEQ ID NO: 12)

[0161] [Table 2]

[0162] SARS-CoV-2 deltaspike-ferritin fusion protein polypeptide sequence (SEQ ID NO: 13)

[0163] [Table 3]

[0164] SARS-CoV-2 Omicron BA.4 / 5 spike-ferritin fusion protein polypeptide sequence (SEQ ID NO: 14) (leader sequence underlined)

[0165] [Table 4]

[0166] T7 promoter (SEQ ID NO: 15) TAATACGACTCACTATAAGG

[0167] SARS-CoV-2 XBB.1.5 spike protein-linker-ferritin RNA sequence (SEQ ID NO: 16)

[0168] mRNA construct sequence encoding SARS-CoV-2 XBB.1.5 spike-ferritin fusion protein (SEQ ID NO: 17)

[0169] SARS-CoV2 Omicron XBB.1.5 Spike-Ferritin Fusion Protein Polypeptide Sequence (Leader Sequence Underlined) (SEQ ID NO: 18)

[0170] [Table 5]

Claims

1. 1. A method of inducing a pan-salvecoronavirus variant immune response in an individual who has previously received one or more doses of a first SARS-CoV-2 vaccine against one or more first salvecoronavirus variants (Variant 1), the method comprising administering to the individual one or more doses of a second SARS-CoV-2 vaccine; the second SARS-CoV-2 vaccine comprises an mRNA encoding a single spike (S) protein or an immunogenic fragment or immunogenic variant thereof from a salve coronavirus variant (variant 2) different from variant 1; the S protein is encoded as an S protein-multimerization subunit fusion; The method induces a pan-variant immune response in the individual against the sarcocoronavirus variant 1 and the sarcocoronavirus variant 2, and induces an immune response against one or more additional sarcocoronavirus variants that are different from the variants 1 and 2.

2. 2. The method of claim 1, wherein the S protein-multimerization subunit fusion is a protein-ferritin subunit fusion.

3. 3. The method of claim 1 or 2, wherein the mRNA of the second SARS-CoV-2 vaccine is formulated in a lipid nanoparticle (LNP).

4. The method of any one of claims 1 to 3, wherein said Mutant 2 is SARS-CoV-2 Omicron.

5. 5. The method of claim 4, wherein the variant 2 is selected from subvariants BA.1, BA.2, BA.2.86, BA.3, BA.4 / 5, BQ.1, BQ.1.1, JN.1, XBB.1, or XBB.1.

5.

6. 6. The method of claim 5, wherein the submutant is BA.4 / 5.

7. 6. The method of claim 5, wherein the subvariant is XBB.1.

5.

8. The method of any one of claims 1 to 7, wherein the S protein or immunogenic fragment or immunogenic variant thereof comprises a K986P and / or a V987P mutation.

9. 7. The method of claim 6, wherein the second SARS-CoV-2 vaccine comprises the mRNA sequence of SEQ ID NO:

11.

10. 8. The method of claim 7, wherein the second SARS-CoV-2 vaccine comprises the mRNA sequence of SEQ ID NO:

17.

11. 11. The method of any one of claims 1 to 10, wherein the first SARS-CoV-2 vaccine does not comprise a nucleic acid encoding a salvecoronavirus S protein in the form of a fusion protein capable of assembling in vivo to form nanoparticles.

12. 12. The method of any one of claims 1 to 11, wherein the method induces an immune response against one or more additional salvecoronavirus variants that are mutationally distinct from said variant 1 and / or said variant 2.

13. 13. The method of any one of claims 1 to 12, wherein the second SARS-CoV-2 vaccine is a monovalent vaccine.

14. 13. The method of any one of claims 1 to 12, wherein the second SARS-CoV-2 vaccine is a bivalent vaccine comprising an additional mRNA encoding a single spike (S) protein or an immunogenic fragment or immunogenic variant thereof, wherein the S protein is encoded as an S protein-multimerization subunit fusion and is distinct from variant 2 and is derived from the same or a different salvecoronavirus variant as variant 1.

15. 15. The method of claim 14, wherein the S protein encoded by the additional mRNA is selected from Wuhan D614G, alpha, beta, or delta mutant S protein.

16. 16. The method of claim 15, wherein the additional mRNA of the second SARS-CoV-2 vaccine comprises the mRNA sequence of SEQ ID NO:9 or SEQ ID NO:

10.

17. 17. The method of any one of claims 1-16, wherein the first dose of the second SARS-CoV-2 vaccine is administered to the individual at least 4 months after administration of the final dose of the first SARS-CoV-2 vaccine.

18. 18. The method of claim 17, wherein the first dose of the second SARS-CoV-2 vaccine is administered to the individual at least 6 months after administration of the final dose of the first SARS-CoV-2 vaccine.

19. 1. An immunogenic composition comprising mRNA encoding a single spike (S) protein, or an immunogenic fragment or immunogenic variant thereof, from a first salvecoronavirus variant for use in inducing a pan-salvecoronavirus variant immune response in an individual who has previously received one or more doses of a first SARS-CoV-2 vaccine comprising or encoding an immunogen from a second salvecoronavirus variant, the S protein is encoded as an S protein-multimerization subunit fusion; An immunogenic composition for use, wherein the immunogenic composition is used to induce an immune response against the first salvecoronavirus variant and the second salvecoronavirus variant, and against at least a third salvecoronavirus variant.

20. 20. The immunogenic composition for use according to claim 19, wherein the S protein-multimerization subunit fusion is a protein-ferritin subunit fusion.

21. 21. The immunogenic composition for use according to claim 19 or 20, wherein the mRNA is formulated in a lipid nanoparticle (LNP).

22. The immunogenic composition for use according to any one of claims 19 to 21, wherein said first salvecoronavirus variant is SARS-CoV-2 Omicron.

23. 23. The immunogenic composition for use of claim 22, wherein the SARS-CoV-2 Omicron mutant is selected from subvariants BA.1, BA.2, BA.2.86, BA.3, BA.4 / 5, BQ.1, BQ.1.1, JN.1, XBB.1, or XBB.1.

5.

24. 24. The immunogenic composition for use according to claim 23, wherein the subvariant is BA.4 / 5.

25. 24. The immunogenic composition for use according to claim 23, wherein the subvariant is XBB.1.

5.

26. The immunogenic composition for use according to any one of claims 19 to 25, wherein the S protein or immunogenic fragment or immunogenic variant thereof comprises the K986P and / or V987P mutation.

27. 25. The immunogenic composition for use according to claim 24, wherein the mRNA comprises or consists of the mRNA sequence of SEQ ID NO:

11.

28. 26. The immunogenic composition for use according to claim 25, wherein the mRNA comprises or consists of the mRNA sequence of SEQ ID NO:

17.

29. 29. The immunogenic composition for use according to any one of claims 19 to 28, wherein the first SARS-CoV-2 vaccine does not comprise a nucleic acid encoding a salvecoronavirus S protein in the form of a fusion protein capable of assembling in vivo to form nanoparticles.

30. 30. The immunogenic composition for use of any one of claims 19 to 29, wherein the third salvecoronavirus variant is mutationally distinct from the first salvecoronavirus variant and / or the second salvecoronavirus variant.

31. The immunogenic composition for use according to any one of claims 19 to 30, wherein said immunogenic composition is a monovalent composition.

32. 31. The immunogenic composition for use of any one of claims 19 to 30, wherein the immunogenic composition is a bivalent composition further comprising a second mRNA encoding a single spike (S) protein or an immunogenic fragment or immunogenic variant thereof, wherein the S protein is encoded as an S protein-multimerization subunit fusion and is derived from a sarcocoronavirus variant that is different from the first sarcocoronavirus variant and that is the same as or different from the second sarcocoronavirus variant.

33. 33. The immunogenic composition for use according to claim 32, wherein the S protein or immunogenic fragment or immunogenic variant thereof encoded by the second mRNA is derived from a variant selected from Wuhan D614G, alpha, beta, or delta SARS-CoV2.

34. 34. The immunogenic composition for use according to claim 33, wherein the second mRNA comprises the mRNA sequence of SEQ ID NO: 9 or SEQ ID NO: 10.

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