Patent Application
20240358812
The present invention relates to a vaccine composition for preventing and/or treating a respiratory system infection such as a human metapneumovirus infection of the respiratory system. This vaccine composition comprises two or more modified human metapneumovirus (hMPV) F proteins or variants thereof provided in a pre-fusion and/or post-fusion conformation form.
Currently no vaccine or specific antiviral drug is available to prevent or treat hMPV infections in subjects such as humans or animals. Infants, some categories of young children below 5 years, elderly above 65 years and immunocompromised patients are particularly at risk to develop severe bronchiolitis or pneumonia due to a hMPV infection. However, vaccine development is challenging because for example the neutralizing antibody response induced by a natural hMPV infection is unfortunately not long lasting, declines over time and wherein the specific memory B cell response is weak (Falsey, A. R.; Hennessey, P. A.; Formica, M. A.; Criddle, M. M.; Biear, J. M.; Walsh, E. E. Humoral immunity to human metapneumovirus infection in adults. Vaccine 2009, 28, 1477-1480).
Phylogenic analysis of genomic sequences from various hMPV strains and clinical isolates revealed two main genotypes (lineages), namely A and B, each divided into subgroups (five sub-lineages), A1, A2a/A2b, B1 and B2 (van den Hoogen B G, Herfst S, Sprong L, Cane P A, Forleo-Neto E, Swart R L de, Osterhaus A D M E, Fouchier R A M (2004) Antigenic and genetic variability of human metapneumoviruses. Emerging infectious diseases 10(4):658-66).
Protection against hMPV is mainly afforded by neutralizing antibodies directed against the fusion (F) glycoprotein (Williams et al. (2007) A Recombinant Human Monoclonal Antibody to Human Metapneumovirus Fusion Protein That Neutralizes Virus In Vitro and Is Effective Therapeutically In Vivo. J Virol 81(15): 8315-8324; Battles et al. (2017) Nat Commun. 16; 8(1): 1528). The F protein is immunodominant and quite conserved between hMPV strains. Rare mutations in the F protein do not result in precarious loss of neutralizing epitopes, so that hMPV subgroups and genotypes are quite stable genetically over time (Yang C F, Wang C K, Tollefson S J, Piyaratna R, Lintao L D, Chu M, Liem A, Mark M, Spaete R R, Crowe J E, Jr, Williams J V (2009) Genetic diversity and evolution of human metapneumovirus fusion protein over twenty years. Virol J 6:138). Cross-protection between genotypes (A and B) and subgroups (A1, A2a, A2b, B1 and B2) was obtained in some animal models, but data are controversial. For instance, induction of cross-protective immunity upon immunization with the soluble F protein isolated from A or B genotype was demonstrated in hamsters (Nerfst et al. 2007. Journal of General Virology (2007), 88, 2702-2709). Conversely, the in vitro study performed with sera from ferrets infected with one genotype did not neutralize the virus of another genotype (Kahn J. S. (2006) Epidemiology of human metapneumovirus. Clin Microbiol 19(3):546-557). The immunogenic response to different hMPV genotypes in humans is not yet well-understood (Rahman et al. (2018) Epidemiological studies in Bangladesh. J Med Virology 2018:1-6). Therefore, circulation of numerous hMPV variants may create complications for developing a vaccine with a broad coverage.
The hMPV F protein mediates fusion of the viral membrane with the cellular membrane to allow viral ribonucleoprotein entry into the cell cytoplasm and initiation of virus replication (Cox R G, Livesay S B, Johnson M, Ohi M D, Williams J V (2012) The human metapneumovirus fusion protein mediates entry via an interaction with RGD-binding integrins. J Virol 86: 12148-12160). The F protein is a type I integral membrane protein that comprises at its C-terminus a hydrophobic transmembrane (TM) domain anchoring the protein in the viral membrane and a short cytoplasmic tail. The native F protein is synthesized as an inactive single-chain precursor F0, which is activated after cleavage by a cell protease generating two polypeptide chains, F1 and F2 (see
Several studies showed that both pre-fusion and post-fusion F protein forms possess antigenic epitopes and are able to elicit neutralizing antibodies (Wen et al. (2012) Structure of the Human Metapneumovirus Fusion Protein with Neutralizing Antibody Identifies a Pneumovirus Antigenic Site. Nat Struct Mol Biol. 19(4): 461-463; Battles et al. (2017) Nat Commun. 16, 8(1):1528; Huang et al. (2019) Antibody Epitopes of Pneumovirus Fusion Proteins. Front Immunol. 10, 2778, review). For instance, Melero's group demonstrated that the recombinant pre-fusion F protein is immunogenic and elicits a good neutralizing antibody response (Melero J A & Más V. (2015) The Pneumovirinae fusion (F) protein: A common target for vaccines and antivirals. Virus Research 209:128-135; Michael B Battles, Vicente Más, Eduardo Olmedillas, Olga Cano, Mónica Vázquez, Laura Rodriguez, José A Melero, Jason S McLellan. Nat Commun. 2017 Nov. 16; 8(1):1528. doi: 10.1038/s41467-017-01708-9). In another study, it was shown that the recombinant post-fusion F protein was able to deplete hMPV-neutralizing antibodies from seropositive human sera (Más V, Rodriguez L, Olmedillas E, Cano O, Palomo C, Terrón MC, Luque D, Melero J A, McLellan J S. (2016) Engineering, Structure and Immunogenicity of the Human Metapneumovirus F Protein in the Postfusion Conformation. PLoS pathogens. 12(9)). One more group has disclosed modifications in the F protein leading to stabilization of the pre-fusion conformation and their applicability for vaccine development (see U.S. Pat. No. 10,420,834 patent).
Previously, we have demonstrated induction of high titer neutralizing antibodies and protection of mice upon immunization with the stabilized pre-fusion form of the hMPV F protein (see WO2020234300 A1). In this study, five F protein candidates formulated as single immunogens have shown promising protective efficacy in the lung infection model. However, creating an improved vaccine that is more effective against multiple hMPV strains and clinical isolates is important. To date, no attempts to combine the pre- and post-fusion conformations of the F protein in a vaccine formulation have been described.
The present invention provides compositions comprising the combination of two or more modified recombinant hMPV F proteins or variants thereof provided in the pre-fusion and/or post-fusion conformations. These modified recombinant proteins are derived from the different hMPV genotypes, A and B, or from the same genotype, but different subgroups, or both. The present invention further provides protein constructs and expression vectors for producing said modified recombinant proteins. The present invention also provides immunogenic compositions (such as vaccines) able to induce specific immune responses and/or enable protection against a hMPV infection. Use of specific combinations of two or more F proteins allows achieving protection against homologous and heterologous hMPV strains. The present invention also relates to methods of producing disclosed recombinant proteins and immunogenic compositions, as well as methods of using them for treating and/or preventing human or animal subjects with mild, moderate or severe hMPV infections.
The problem underlying the present invention is to develop an immunogenic composition (vaccine) that would potentiate strong and long-lasting immune responses and provide better protection against various hMPV strains and clinical isolates than known immunogenic compositions containing, e.g. a single hMPV F protein existing either in the pre-fusion or post-fusion conformation.
The problem underlying this invention is solved by providing compositions comprising two or more different F proteins or variants thereof provided in different conformation forms, i.e. the pre- or post-fusion conformations. Moreover, such a solution also includes two or more F proteins formulated in one composition derived from different hMPV strains that belong to the same or distinct genotypes.
In order to solve the problem, a couple of F protein candidates from different hMPV genetic groups and subgroups thereof were produced as modified (i.e. stabilized in the post- or pre-fusion conformation) recombinant proteins and studied in several combinations with each other for immunogenicity and protective efficacy in a mouse challenge model or other functional model. In particular, mice immunized with the combination of pre-/post-fusion F proteins from subgroup A1 and B1 were challenged with the virus of subgroup B1 and induction of neutralizing antibodies and viral load were tested. Alternatively, mice immunized with the combination of pre-/post-fusion F proteins from subgroup A1 and/or B1 can be challenged with the virus of subgroup A1. Otherwise, protection of mice immunized with the combination of pre-/post-fusion F proteins from subgroup A1 and/or B1 can be evaluated after challenge with the hMPV subgroup A2a, A2b or B2. As the result, cross-protection between two genotypes A and B and different subgroups is observed.
According to one embodiment, the first modified (stabilized) F protein of the composition is present in the pre-fusion conformation. Said pre-fusion F protein consists of a single-chain polypeptide similar to the F ectodomain but lacking the protease cleavage site and the fusion peptide (FP) between F1 and F2 domains. Instead, the single-chain F protein comprises a heterologous peptide linker between F1 and F2 domains, which contains at least one cysteine residue forming a non-natural disulfide (S—S) bond with another cysteine residue in the F1 domain and thus stabilizing the pre-fusion conformation. Alternatively, the pre-fusion hMPV F protein may comprise two polypeptide chains, i.e. F1 and F2 domains covalently linked by two or more S—S bonds. Such protein may contain mutation(s) stabilizing the pre-fusion conformation.
According to yet another embodiment, the second F protein of the composition is a modified (stabilized) F protein present in the post-fusion conformation. This protein consists of two polypeptide chains and contains one or more mutation(s) stabilizing the post-fusion conformation.
According to another embodiment of the invention, the pre- and/or post-fusion F protein may comprise an amino acid sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity to the amino acid sequence of the parental F protein. A modified F protein having a high sequence identity with a reference parental F protein is also referred to herein as a variant. Generally, homologs or variants of a protein possess a relatively high degree of sequence identity when aligned using standard methods well known in the art. Importantly, a homologous F protein or variant is similarly immunogenic and protective as the parental F protein.
Additionally, the pre- and post-fusion F proteins of the present invention are recombinant proteins without transmembrane domain (referred herein also as “TM”) and/or cytoplasmic tails produced in heterologous host cells as homo- or preferably as hetero- or homo-trimers. To facilitate the trimerization process, one or more specific modification(s) or trimerization helper domain(s) may be introduced into the C-terminal part of the F protein.
According to yet another embodiment, one pre- and one post-fusion F protein are formulated in a single composition further comprising a pharmaceutically exactable carrier and/or excipient. Beside the F proteins, such composition may comprise one or more additional antigen, for instance, another hMPV protein or another antigen directed to another pathogen causing infection of the respiratory system.
Typically, the composition of the present invention is an immunogenic composition (a vaccine) able to elicit hMPV neutralizing antibodies and a specific T-cell response directed against hMPV. Optionally, the immunogenic composition may further comprise an adjuvant for enhancing such immune response and/or shifting the immune response to a desirable Th1-type direction. Generally, an immune response (neutralizing antibody titer) induced by the immunogenic composition of the present invention is sufficient to protect against an hMPV infection. Additionally, the immunogenic composition comprising the F protein or variants thereof in both conformation forms elicits an immune response (neutralizing antibody titer) superior to immune response (neutralizing antibody titers) elicited by an equal amount of the single F protein present either in the pre- or post-fusion conformation.
The immunogenic compositions of the present invention are able to provide protection against any hMPV strain NL/1/00, NL/17/00, TN/94-49, NCL174, CAN97-83, NL/1/9, NDL00-1, C1-334, CAN97-82 and TN/89-515.
Furthermore, the immunogenic compositions of the present invention are able to provide protection against more than one hMPV strain, particularly against strains that belong to different genotypes or different subgroups of one genotype. For instance, the immunogenic composition can provide protection against A1, A2a and/or A2b subgroup(s), alternatively, against B1 and/or B2 subgroup(s), or against both A and B genotypes. Especially, cross-protection between A and B genotypes is desirable. The preferred immunogenic compositions of the present invention comprise the pre-fusion F protein of A1 subgroup which can provide protection against both A and B genotypes.
According to the present invention, the immunogenic compositions (vaccines) of the present invention are useful for the treatment and/or prevention of human and/or animal subjects against an hMPV infection.
In a further embodiment, the present invention provides a method for generating an immune response with a modified F protein or a variant thereof available in the pre- or post-fusion conformation. Such method comprises administering to the subject a therapeutically effective amount of an immunogenic composition containing both conformation forms of the F protein.
In yet one embodiment, the present invention provides a method for treating and/or preventing subjects against hMPV infection or associated disease. Accordingly, the immunogenic composition (vaccine) is administered to a subject via a parenteral route (e.g. intramuscular, intradermal, or subcutaneous) or a mucosal route (e.g. intranasal, oral). As the result, high titers of anti-F protein neutralizing antibodies are generated that assure protection of the immunized subject against hMPV. In a preferred embodiment, the present vaccine induces protective immune responses against more than one hMPV strain, more preferably, against hMPV strains of the same genotype, most preferably, against both genotypes, A and B. In yet one embodiment, the dosage of the vaccine is sufficient to provide a robust anti-hMPV protection against a hMPV infection. Additionally, the method may comprise a prime-boost immunization with the same or different immunogenic compositions comprising modified F proteins or variants thereof derived from the different hMPV subgroups and/or genotypes. For instance, the prime immunization may be done with the vaccine comprising F proteins of genotype A, while the boost immunization may be done with the vaccine comprising F proteins of genotype B. In such a way, cross-protection between genotypes A and B can be achieved.
Furthermore, the method may comprise only a boost immunization with the immunogenic compositions comprising modified F proteins or variants thereof derived from the same or different hMPV genotypes (A and/or B) or subgroups (A1, A2a, A2b, B1 and/or B2) in particularly for elderly or adults (e.g. adults at risks) since most of these populations have already been exposed.
Finally, the present invention provides a method for producing the recombinant modified F proteins existing in the stabilized pre-fusion or post-fusion conformations and immunogenic compositions comprising these proteins. The aforementioned method includes the following steps: i) expressing the recombinant modified F proteins from the corresponding nucleic acid molecules inserted in expression vectors in host cells, ii) purifying said recombinant F proteins; and iii) combining said purified recombinant proteins with the pharmaceutically acceptable carrier and/or excipient, and optionally with an adjuvant in a pharmaceutical composition or vaccine.
More in particular the following embodiments are provided:
1. An immunogenic composition comprising a combination of a stabilized pre-fusion and post-fusion conformation forms of the human metapneumovirus (hMPV) F protein or fragments thereof, wherein said pre- and post-fusion F proteins or fragments thereof are derived from the same or different genotypes A and B.
2. The immunogenic composition of embodiment 1, wherein the pre- and post-fusion F proteins are derived from the subgroups A 1 and/or A2a and/or A2b.
3. The immunogenic composition of embodiment 1, wherein the pre- and post-fusion F proteins are derived from the subgroups B1 and/or B2.
4. The immunogenic composition of embodiment 1, wherein the pre-fusion F protein is derived from the genotype A, subgroup A1 or A2a or A2b, and the post-fusion F protein is derived from the genotype B, subgroup B1 or B2.
5. The immunogenic composition of embodiment 1, wherein the pre-fusion F protein is derived from the genotype B, subgroup B1 or B2, and the post-fusion F protein is derived from the genotype A, subgroup A1 or A2a or A2b.
6. The immunogenic composition of embodiment 1, comprising i) the pre-fusion F protein of the subgroup A1 and the post-fusion F protein of the subgroup B1; or ii) the pre-fusion F protein of the subgroup A1 and the post-fusion F protein of the subgroup B2; or iii) the pre-fusion F protein of the subgroup A2a or A2b and the post-fusion F protein of the subgroup B1; or iv) the pre-fusion F protein of the subgroup A2a or A2b and the post-fusion F protein of the subgroup B2; or v) the pre-fusion F protein of the subgroup B1 and the post-fusion F protein of the subgroup A1; or vi) the pre-fusion F protein of the subgroup B1 and the post-fusion F protein of the subgroup A2a or A2b; or vii) the pre-fusion F protein of the subgroup B2 and the post-fusion F protein of the subgroup A1; or viii) the pre-fusion F protein of the subgroup B2 and the post-fusion F protein of the subgroup A2a or A2b.
7. The immunogenic composition of any of preceding embodiment, wherein the pre-fusion and post-fusion F proteins are recombinant proteins.
8. The immunogenic composition of any preceding embodiment, wherein the F protein lacks the cytoplasmic tail and/or transmembrane domain.
9. The immunogenic composition of any preceding embodiment, wherein the pre- and/or post-fusion F protein has an amino acid sequence, which is a modified amino acid sequence of the native F protein derived from any hMPV strain or clinical isolate.
10. The immunogenic composition of embodiment 9, wherein the native F protein sequence is selected from the group consisting of the amino acid sequences of SEQ ID NO: 1 to 10 that are derived from the hMPV strains NL/1/00, NL/17/00, TN/94-49, NCL174, CAN97-82, CAN97-83, NL/1/9, NDL00-1, C1-334 and TN/89-515.
11. The immunogenic composition of any preceding embodiment, wherein the pre- and/or post-fusion F protein comprises at least one mutation (substitution or deletion), preferably up to 10 mutations, relative to the native F protein sequence of SEQ ID NO: 1 to 10 and 49.
12. The immunogenic composition of any preceding embodiment, wherein the pre-fusion F protein comprises one or more amino acid substitution(s) to cysteine, which introduce one or more non-native disulfide bond(s) that stabilize the pre-fusion conformation.
13. The immunogenic composition of embodiment 12, wherein the cysteine substitution is introduced at any one of positions 103-120 and any one of positions 335-345; any one of positions 107-118 and any one of positions 335-342;
14. The immunogenic composition of any preceding embodiment, wherein the pre-fusion F protein consists of a single polypeptide chain stabilized by at least one non-natural disulfide bond.
15. The immunogenic composition of embodiment 14, wherein the single-chain pre-fusion F protein lacks a protease cleavage site between F1 and F2 domains relative to the native F protein.
16. The immunogenic composition of embodiment 14 and 15, wherein the single-chain pre-fusion F protein comprises a substitution of arginine at position 102 relative to the amino acid positions of the native F protein for another amino acid, preferably glycine.
17. The immunogenic composition of embodiments 14 to 16, wherein the amino acid residues at positions 103-118 of the native F protein are replaced with a heterologous linker consisting of 1 to 5 amino acid residues including cysteine residue, wherein said cysteine residue forms a disulfide bond with a cysteine residue in the F1 domain.
18. The immunogenic composition of embodiment 17, wherein the heterologous linker comprises at least one alanine, glycine or valine residue, preferably the linker has the sequence CGAGA or CGAGV.
19. The immunogenic composition of embodiments 14 to 18, wherein the pre-fusion F protein comprises one or more substitution(s) at positions corresponding to positions 49, 51, 67, 80, 137, 147, 159, 160, 161, 166, 177, 258, 266, 480 and/or 481 of the native hMPV F protein.
20. The immunogenic composition of embodiment 19, wherein the substitution is selected from the group consisting of T49M, E80N, I137W, A147V, A159V, T160F, A161M, I67L, I177L, F258I, S266D, 1480C and/or L481C.
21. The immunogenic composition of embodiments 14 to 20, wherein the single-chain pre-fusion F protein comprises one of the following substitution combinations:
22. The immunogenic composition of any embodiments 14 to 21, wherein the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 11 (L7F_A1_23)
23. The immunogenic composition of any embodiments 14 to 21, wherein the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 12 (L7F_B1_23).
24. The immunogenic composition of any embodiments 14 to 21, wherein the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 13 (L7F_A1_23.2).
25. The immunogenic composition of any embodiments 14 to 21, wherein the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 14 (L7F_B1_23.2).
26. The immunogenic composition of any embodiments 14 to 21, wherein the pre-fusion F protein comprises or consist of the amino acid sequence of SEQ ID NO: 15 (sF_A1_K_L7)
27. The immunogenic composition of any embodiments 14 to 21, wherein the pre-fusion F protein comprises or consist of the amino acid sequence of SEQ ID NO: 50 (sF_B1_K_L7).
28. The immunogenic composition of any embodiments 14 to 21, wherein the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 16 (L7F_A1_31)
29. The immunogenic composition of any embodiments 14 to 21, wherein the pre-fusion F protein comprises or consist of the amino acid sequence of SEQ ID NO: 51 (L7F_B1_31).
30. The immunogenic composition of any embodiments 14 to 21, wherein the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 17 (L7F_A1_33)
31. The immunogenic composition of any embodiments 14 to 21, wherein the pre-fusion F protein comprises or consist of the amino acid sequence of SEQ ID NO: 52 (L7F_B1_33).
32. The immunogenic composition of any embodiments 14 to 21, wherein the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 18 (construct L7F_A1_4.2)
33. The immunogenic composition of any embodiments 14 to 21, wherein the pre-fusion F protein comprises or consist of the amino acid sequence of SEQ ID NO: 53 (construct L7F_B1_4.2).
34. The immunogenic composition of any embodiments 1 to 13, wherein the pre-fusion F protein is a two-polypeptide-chain protein and comprises or consists of the amino acid sequence of SEQ ID NO: 19.
35. The immunogenic composition of any embodiments 1 to 13, wherein the pre-fusion F protein is a two-polypeptide-chain protein and comprises or consists of the amino acid sequence of SEQ ID NO: 20.
36. The immunogenic composition of any embodiments 1 to 13, wherein the stabilized post-fusion F protein comprises the deletion of the amino acid residues at positions 103 to 111, replacement of R102 by a linker KKRKRR and the substitution G294E relative to the amino acid positions of the native F protein.
37. The immunogenic composition of embodiment 32, wherein the post-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 21 (sF_A1_MFur).
38. The immunogenic composition of embodiment 32, wherein the post-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 22 (sF_B1_MFur).
39. The immunogenic composition of any embodiments 1 to 38, wherein the pre- and/or post-fusion F protein: i) comprises the amino acid sequence having at least 80% sequence identity to the amino acid sequence selected from the group consisting of SEQ ID NO: 1 to 22 and 49 to 53, and ii) its immunogenicity is similar to immunogenicity of the parental F protein of SEQ ID NO: 1 to 22 and 49 to 53.
40. The immunogenic composition of any embodiments 1 to 38, wherein the pre- or post-fusion F protein i) comprises the amino acid sequence having at least 90% sequence identity to the amino acid sequence selected from the group consisting of SEQ ID NO: 1 to 22 and 49 to 53, and ii) its immunogenicity is equal or similar to immunogenicity of the parental F protein of SEQ ID NO: 1 to 22 and 49 to 53.
41. The immunogenic composition of any embodiments 1 to 38, wherein the pre- or post-fusion F protein i) comprises the amino acid sequence having at least 95% sequence identity to the amino acid sequence selected from the group consisting of SEQ ID NO: 1 to 22 and 49 to 53, and ii) its immunogenicity is equal or similar to immunogenicity of the parental F protein of SEQ ID NO: 1 to 22 and 49 to 53.
42. The immunogenic composition of any preceding embodiment, wherein the pre- and post-fusion hMPV F protein comprises a trimerization helper domain (foldon) having the sequence of SEQ ID NO: 23 to 28 or a variant thereof.
43. The immunogenic composition of any preceding embodiment, wherein the F protein is produced as a homo- or hetero-trimer.
44. The immunogenic composition of any preceding embodiment, wherein the composition comprises a further hMPV antigen.
45. The immunogenic composition of embodiment 44, wherein the further hMPV antigen is the M protein comprising or consisting of the amino acid sequence of SEQ ID NO: 41 or a fragment thereof, or a variant thereof having at least 80% sequence identity thereto.
46. The immunogenic composition of any preceding embodiment, wherein the composition further comprises at least one pharmaceutically acceptable carrier and/or excipient.
47. The immunogenic composition of any preceding embodiment, wherein the composition further comprises an adjuvant.
48. The immunogenic composition of embodiment 47, wherein the adjuvant is selected from the group consisting of alum, CpG ODN, I-ODN, IC31®, MF59®, MPL, GLA-SE, GLA-3M-052-LS, 3M-052-alum, AddaVax™, AS03, AS01, QS21, or a combination thereof.
49. The immunogenic composition of embodiment 47, wherein the adjuvant is alum.
50. The immunogenic composition of embodiment 47, wherein the adjuvant is IC31®.
51. The immunogenic composition of embodiment 47, wherein the adjuvant is GLA-SE.
52. The immunogenic composition of embodiment 43, wherein the adjuvant is 3M-052-alum.
53. The immunogenic composition of embodiment 47, wherein the adjuvant is GLA-3M-052-LS.
54. The immunogenic composition of embodiment 47, wherein the adjuvant is AddaVax™.
55. The immunogenic composition of embodiment 47, wherein the adjuvant consists of alum and CpG1018.
56. The immunogenic composition of embodiment 47, wherein the adjuvant consists of alum and IC31®.
57. The immunogenic composition of embodiment 47, wherein the adjuvant consists of alum and MPL.
58. The immunogenic composition of any preceding embodiment, wherein the composition is capable to elicit neutralizing antibodies against the pre-fusion and/or post-fusion F protein(s).
59. The immunogenic composition of any preceding embodiment, wherein the composition provides a superior immune response (neutralizing antibody titers) as compared to immune response (neutralizing antibody titers) elicited by a composition comprising either the pre- or post-fusion F protein used at the same total protein amount.
60. The immunogenic composition of any preceding embodiment, wherein the composition provides protection against infection with at least one, preferably more than one homologous or heterologous hMPV strain.
61. The immunogenic composition of embodiment 60, wherein the homologous hMPV strain is of the same genotype A or B as the F proteins of the immunogenic composition.
62. The immunogenic composition of embodiment 60, wherein the heterologous hMPV strain is of the different genotype A or B as the F proteins of the immunogenic composition.
63. The immunogenic composition of embodiment 60, wherein the composition comprising the pre- and post-fusion F proteins of either genotype A (subgroup A1 or A2a or A2b) or genotype B (subgroup B1 or B2) provides protection against hMPV of a different genotype.
64. The immunogenic composition of embodiment 60 and 61, wherein the composition comprising the pre- and post-fusion F proteins of subgroup A1 and/or A2a and/or A2b provides protection against hMPV of subgroup A 1 and/or A2a and/or A2b.
65. The immunogenic composition of embodiment 60 and 61, wherein the composition comprising the pre- and post-fusion F proteins of genotype B1 and/or B2 provides protection against hMPV of subgroup B1 and/or B2.
66. The immunogenic composition of embodiment 60 and 62, wherein the composition comprising the pre- and post-fusion F proteins of genotype A1 and/or A2a and/or A2b provides protection against hMPV of subgroup B1 and/or B2.
67. The immunogenic composition of embodiment 60 and 62, wherein the composition comprising the pre- and post-fusion F proteins of subgroup B1 and/or B2 provides protection against hMPV of subgroup A 1 and/or A2a and/or A2b.
68. The immunogenic composition of any preceding embodiment, wherein the composition is a vaccine.
69. The immunogenic composition according to any preceding embodiment for use as a medicament.
70. The immunogenic composition according to any preceding embodiment for treating and/or preventing hMPV infection and associated disease in a subject.
71. A method for generating an immune response to the hMPV F protein in a subject, wherein the method comprises administering to the subject an effective amount of the immunogenic composition according to any previous embodiments 1 to 70.
72. The method of embodiment 71, wherein the immunogenic composition is administered intramuscularly, intradermally, subcutaneously, mucosally, intrarectally, or orally.
73. The method of embodiment 71 and 72, wherein the method comprises a prime-boost administration of the immunogenic composition according to any embodiment 1 to 70, wherein the prime-boost is done with the same immunogenic composition, and wherein the composition comprises the F proteins of both A and B genotypes.
74. The method of embodiment 71 and 72, wherein the method comprises a prime-boost administration of the immunogenic composition according to any embodiments 1 to 70, wherein the prime administration is done with the composition comprising the F proteins of the genotype A and the boost administration is done with the composition comprising the F proteins of the genotype B, or vise versa.
75. The method of embodiment 71 and 72, wherein the method comprise only a boost immunization of the elderly or adult subject with the immunogenic composition according to any embodiment 1 to 70, wherein the composition comprises the F proteins derived from either one or both A and B genotypes.
76. A method for treating and/or preventing hMPV infection in a subject, wherein the method comprises administering to the subject a therapeutically effective amount of the immunogenic composition according to any of embodiments 1 to 70 in order to generate neutralizing antibodies against the pre- and post-fusion hMPV F proteins and provide protection against the hMPV strains of at least one genotype A or B.
77. A method for producing the immunogenic composition according to embodiments 1 to 70, wherein the method comprises i) expression of the recombinant pre- and post-fusion F protein from the corresponding nucleic acid molecule inserted in an expression vector in a host cell, ii) purifying the expressed recombinant F protein; and iii) combining the purified recombinant protein with a pharmaceutically acceptable carrier and/or excipient, optionally with an adjuvant.
An object of the present invention is to provide an hMPV subunit vaccine for treating and/or preventing subjects against numerous hMPV strains. The subunit vaccine is based on a modified hMPV F protein stabilized in one of the following conformations: pre-fusion and post-fusion (see
hMPV strains are classified into two genotypes: A and B, each divided into two subgroups A1, A2a, A2b, B1 and B2. The disclosed herein modified F proteins or fragments thereof can be derived from any hMPV strain or clinical isolate. Preferably, two F proteins in one composition (or vaccine) belong to different genetic subgroups of the same genotype, even more preferably, to different genotypes. Examples of native F protein sequences derived from different strains are shown in Table 1.
In one aspect, the present invention relates to a soluble F protein, which mediates fusion of the virus and cell membrane during the infection process. The F protein is an integral membrane protein that spans the viral membrane once and contains at the N-terminus a cleavable signal sequence and at the C-terminus a hydrophobic TM domain anchoring the protein in the membrane and a short cytoplasmic tail (see
For producing F proteins in the stabilized pre-fusion and post-fusion conformations, native F proteins were modified by recombinant technology (gene engineering); and DNA constructs were expressed in recombinant hosts.
According to one embodiment, the recombinant pre-fusion F protein was produced as a single-chain polypeptide. The single-chain F polypeptide has amino acid sequence similar to the sequence of F ectodomain, but lacking the fusion peptide (FP), which spans the amino acid residues at positions 103-118 of the native F protein, in particular, the native F protein sequence of SEQ ID NO: 1 to 10 and 49. Additionally, the single-chain F polypeptide lacks a protease cleavage site between the F1 and F2 domains, which is eliminated by introducing a mutation, preferably, at position 102 relative to the amino acid sequence of the native F protein. More preferably, this mutation is a substitution of the arginine residue to glycine (R102G). Furthermore, the pre-fusion F protein comprises at least one additional amino acid modification (such as substitution, deletion or insertion), especially at least one substitution to cysteine. This additional cysteine residue could form a non-natural disulfide (S—S) bond with another cysteine residue that further stabilizes the pre-fusion conformation.
According to yet another embodiment, in the single-chain F protein the F1 and F2 domains are connected by a heterologous peptide linker, which replaces amino acids 103 to 118 of the native F protein. The linker comprises up to five amino acids including alanine, glycine and/or valine, and at least one cysteine. Preferably, the cysteine residue is at position that corresponds to position 103 of the native F protein. Most preferably, the linker has the sequence CGAGA or CGAGV, in which C is at position 103. This cysteine could form a disulfide bond with a cysteine residue of the F1 domain.
According to yet one embodiment, the cysteine residue could be introduced at
According to yet one embodiment, the pre-fusion F protein comprises one or more substitution(s) at positions corresponding to positions 49, 51, 67, 80, 137, 147, 159, 160, 161, 166, 177, 258, 266, 480 and/or 481 relative to the amino acid positions of the native F protein sequence, in particular, the native F protein sequence of SEQ ID NO: 1 to 10. The preferred substitution is selected from the group consisting of T49M, E80N, I137W, A147V, A159V, T160F, A161M, I67L, I177L, F258I, S266D, 1480C and/or L481C.
More preferably, the single-chain pre-fusion F protein comprises one of the following combinations:
In some embodiments, the pre-fusion single-chain F protein may be selected from the group consisting of, but not limited to, the following protein constructs: L7F_A1_23 (SEQ ID NO: 11), L7F_B1_23 (SEQ ID NO: 12), L7F_A1_23.2 (SEQ ID NO: 13), L7F_B1_23.2 (SEQ ID NO: 14), sF_A1_K_L7 (SEQ ID NO: 15), sF_B1_K_L7 (SEQ ID NO: 50), L7F_A1_31 (SEQ ID NO: 16), L7F_B1_31 (SEQ ID NO: 51), L7F_A1_33 (SEQ ID NO: 17), L7F_B1_33 (SEQ ID NO: 52), L7F_A1_4.2 (SEQ ID NO: 18); and/or L7F_B1_4.2 (SEQ ID NO: 53).
In particular, the pre-fusion F protein may comprise or consists of the amino acid sequence of SEQ ID NO: 11 (L7F_A1_23 construct). In particular, the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 13 (L7F_A1_23.2 construct). In particular, the pre-fusion F protein comprises or consist of the amino acid sequence of SEQ ID NO: 15 (sF_A1_K_L7 construct). In particular, the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 16 (L7F_A1_31 construct). In particular, the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 17 (L7F_A1_33 construct). In particular, the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 18 (construct L7F_A1_4.2 construct). In particular, the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 12 (L7_B123 construct). In particular, the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 14 (L7_B1_23.2 construct). In particular, the pre-fusion F protein comprises or consist of the amino acid sequence of SEQ ID NO: 50 (sF_B1_K_L7 construct). In particular, the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 51 (L7F_B1_31 construct). In particular, the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 52 (L7F_B1_33 construct). In particular, the pre-fusion F protein comprises or consists of the amino acid sequence of SEQ ID NO: 53 (construct L7F_B1_4.2 construct).
According to another embodiment, the pre-fusion F protein consists of two polypeptide chains, i.e. distinct F1 and F2 domains connected by two or more S—S bonds, further containing at least one stabilizing mutation, preferably in the F1 domain. Exemplary two-chain pre-fusion F protein is sF_A1_K-E294 construct (SEQ ID NO: 19) and sF_B1_K-E294 construct (SEQ ID NO: 20).
According to yet another embodiment, the second protein of the composition disclosed herein is a modified F protein stabilized in the post-fusion conformation. The post-fusion F protein contains one or more stabilizing mutation(s). Particularly, the stabilized post-fusion F protein comprises the deletion of the amino acid residues at positions 103 to 111, replacement of R102 by a linker KKRKRR and the substitution G294E relative to the amino acid positions of the native F protein of SEQ ID NO: 1 to 9. Examples of the post-fusion F protein constructs are sF_A1_Mfur (SEQ ID NO: 21) and sF_B1_Mfur (SEQ ID NO: 22). Alternatively, the post-fusion construct are sF_A2_Mfur and sF_B2_Mfur.
According to yet another embodiment, the pre- or post-fusion F protein may comprise or consist of the amino acid sequence having at least 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity to the amino acid sequence selected from the group consisting of the sequences of SEQ ID NO: 11 to 22, wherein the percentage sequence identity is determined over the full length of the parental sequence by using the Needleman-Wunsch algorithm (Needleman & Wunsch. (1970) A general method applicable to the search for similarities in the amino acid sequence of two proteins. J Mol. Biol. 48:443-453). Otherwise, the percent sequence identity is determined by dividing the number of matches by the length of the sequence set forth in the identified sequence, or by an articulated length (such as 100 consecutive nucleotides or amino acid residues from a sequence set forth in an identified sequence), followed by multiplying the resulting value by 100. Preferably, the percentage sequence identity is determined over the full length of the sequence. For example, a peptide sequence that has 1166 matches when aligned with a test sequence having 1554 amino acids is 75.0 percent identical to the test sequence (1166÷1554*100=75.0). The percentage of sequence identity value is rounded to the nearest tenth. For example, 75.11, 75.12, 75.13, and 75.14 are rounded down to 75.1, while 75.15, 75.16, 75.17, 75.18, and 75.19 are rounded up to 75.2. Homologs and variants of a protein are typically characterized by possession of at least about 75%, counted over at least 50,100,150, 250, 500 amino acid residues of the reference sequence, over the full length of the reference sequence or over the full length alignment with the reference amino acid sequence. Importantly, such homologous protein or protein variant possesses an immunogenicity and protective efficacy comparable to the immunogenicity and protective efficacy of the parental F protein having a sequence of any SEQ ID NO: 11 to 22, wherein comparable immunogenicity can be measured in ELISA (IC50 value) and/or neutralization assay (PRNT50 value) and the read out is within a +/−50% margin, preferably +/−40%, more preferably +/−30%, 20% or 10% margin.
In an additional embodiment, the pre- and post-fusion F protein of the present invention does not possess a transmembrane domain and a cytoplasmic tail. Nevertheless, it can be produced as a homo- or hetero-trimer. Trimerization can occur due to the sequence spanning the residues 480-495 of the native F protomer, however, trimerization can be facilitated by introducing modification(s) in this region. One modification includes substitution of the vicinal residues I480 and L481 for cysteine that allows introduction of three disulfide bonds across the three protomers in the form of a covalent ring. Another modification is insertion of a trimerization helper, so called foldon domain. Addition of the trimerization helper supports formation of a stable and soluble protein trimer. Availability of cysteine rings in the foldon domain allows forming the disulfide bonds making covalent connection between three protomers. In one embodiment, the foldon domain has the sequence of SEQ ID NO: 23 derived from fibritin of T4 bacteriophage or a modified sequence that contains one or more N-glycosylation site(s) (motif NxT/S, wherein “x” any amino acid residue except proline) helping to hide hMPV non-specific epitope(s). Examples of such modified foldon sequences are of SEQ ID NO: 24 to 28. Alternatively, a variant of the foldon domain may contain structural elements from the GCN4 leucine zipper (Harbury et al. 1993. Science 262:1401) or monomers of self-assembling nanoparticles, e.g., ferritin or lumacine synthase. Additionally, a linker may be used in the combination with a cleavage site, introduced by e.g. replacement of A496 residue. Non-limiting examples of short linkers are: GG, SG, GS, GGG, GGA, GGS, SGG, SSG, SGS, SGA, GGA, SSA and SGGS.
In yet another embodiment, the foldon domain is attached to the C-terminus of the F protein replacing its transmembrane and cytosolic domains. In this case, the glycine residue at the N-terminus of the foldon domain is attached to the C-terminus of the F1 domain directly or via a peptide linker, which may include at least one protease site. For instance, the foldon domain can be attached via the “VSL” (SEQ ID NO: 29) or “VSA” (SEQ ID NO: 30) linker. Such linkers may be used in combinations with a protease cleavage site such as the thrombin cleavage site, TEV (Tobacco etch virus protease) or Factor Xa cleavage site. Such foldon may have the sequence of SEQ ID NO: 42 to 47.
In some embodiments, for easier purification of the recombinant protein the single-chain polypeptide may comprise any purification tag sequences known in the prior art. Examples of polypeptides that aid purification include, but are not limited to, a His-tag, a myc-tag, an S-peptide tag, a MBP tag, a GST tag, a FLAG tag, a thioredoxin tag, a GFP tag, a BCCP, a calmodulin tag, a streptavidin tag, an HSV-epitope tag, a V5-epitope tag and a CBP tag. Preferably, the F proteins of the present invention comprise the His and/or streptavidin tags.
In yet another embodiment, the present invention provides isolated nucleic acid molecules encoding the recombinant hMPV F proteins of SEQ ID NO: 11 to 22 disclosed herein. In one certain embodiment, the nucleic acids encoding the proteins of the present invention comprise or consist of the sequences of SEQ ID NO: 31 to 40. In another embodiment, the nucleic acid encoding the hMPV F proteins may include one or more modification(s), such as substitutions, deletions or insertions. In some embodiments, the present application also encompasses nucleic acid molecules encoding proteins having at least 85%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity to the amino acid sequence of SEQ ID NO: 11 to 22. Preferably, the nucleic acid sequences exhibit between about 80 and 100% (or any value there between) sequence identity to polynucleotide sequences of SEQ ID NO: 31 to 40. Sequence identity can be determined by sequence alignment programs and parameters well known to those skilled in the art. Such tools include the BLAST suite for a local alignment (Altschul S. F., et al. 1997. “Gapped BLAST and PSI-BLAST: a new generation of protein database search programs”, Nucleic Acids Res. 25:3389-3402). A general global alignment can be performed by using the Needleman-Wunsch algorithm (Needleman & Wunsch. 1970. A general method applicable to the search for similarities in the amino acid sequence of two protein. J Mol. Biol. 48:443-453).
In a further embodiment, the nucleic acids described herein may include additional nucleotide sequences encoding segments that can be used to enhance the formation of protein trimers (so called foldon domains) or purification of expressed proteins (purification tags). In some embodiments, the nucleic acids disclosed herein may have codon-optimized sequences. The procedure, known as “codon optimization” is described e.g. in the U.S. Pat. No. 5,547,871. The degeneracy of the genetic code permits variations of the nucleotide sequences of the F proteins, while still producing a polypeptide having the identical amino acid sequence as the polypeptide encoded by the native polynucleotide sequence.
According to yet one embodiment, the pre- and post-fusion F proteins disclosed herein are recombinant proteins produced in a heterologous host cell. The production of the recombinant proteins may be achieved by any suitable methods, including but not limited to transient and/or stable expression of the protein-encoding sequences in a culture of the prokaryotic or eukaryotic cells. The protein-encoding (polynucleotide) constructs are conveniently prepared using standard recombinant techniques (see e.g. Sambrook et al., supra). Polynucleotide sequences encoding the proteins disclosed herein may be included in one or more vectors, which are introduced into a host cell where the recombinant proteins are expressed. Non-limiting examples of vectors that can be used to express sequences encoding the proteins of the present invention include viral-based vectors (e.g., retrovirus, adenovirus, alphavirus, baculovirus or vaccinia virus), plasmid vectors, yeast vectors, insect vectors, mammalian vectors or artificial vectors. Many suitable expression systems are commercially available. The expression vector typically contains coding sequence and expression control elements which allow expression of the coding sequence in a suitable host cell. The present invention provides expression systems designed to assist in expressing and providing the isolated polypeptides. The present application also provides host cells for expression of the recombinant hMPV proteins. In one embodiment, the host cell may be a prokaryote, e.g. E. coli. In another embodiment, the host cell may be an eukaryotic cell, e.g. selected from the group consisting of, but no limited to, EB66® (Valneva SE), Vero, MDCK, BHK-21, MRC-5, WI-38, HT1080, CHO, COS-7, HEK293, Jurkat, CEM, CEMX174, and myeloma cells (e.g., SB20 cells) (many these cell lines are available from the ATCC). Cell lines expressing one or more above described protein(s) can readily be generated by stably integrating one or more expression vector(s) encoding the protein(s) under constitutive or inducible promoter. The selection of the appropriate growth conditions and medium is within the skill of the art.
Methods for producing the recombinant proteins disclosed herein or isolated nucleic acid (DNA or RNA) molecules encoding those proteins are incorporated into the present disclosure. In particular, methods for purifying the recombinant proteins are included. Non-limiting examples of suitable purification from the cell culture medium procedures include centrifugation and/or density gradient centrifugation (e.g. sucrose gradient), filtration, pelleting, and/or column or batch chromatography including ion-exchange, affinity, size exclusion and/or hydrophobic interaction chemistries, tangential filtration, etc. Such methods are known to those of skill in the art and are described in, e.g., Protein Purification Applications: A Practical Approach (E. L. V. Harris and S. Angal., Eds., 1990).
In a further embodiment, the F protein of the present invention may derive from any of the hMPV strain or clinical isolate belonging to either one of two genotype A and B, or subgroup A1, A2a, A2b, B1 or B2.
In a further embodiment, the present invention provides the compositions comprising combinations of at least two F proteins, especially the compositions comprising F proteins existing in the pre- and post-fusion conformations. In general, F proteins may be derived from any of the hMPV strain or clinical isolate. In one embodiment, the composition of the present invention comprises the F proteins derived from the same genotype, A or B, different subgroups, particularly subgroups A1 and A2a and A2b (alternatively, B1 and B2). In another embodiment, the composition of the present invention comprises the F proteins derived from the different genotypes A and B, for instance, subgroups A1 (or A2a and A2b) and B1 (or B2).
In one particular embodiment, the combination comprises the pre- and post-fusion F proteins derived from the genotype A, particularly from the subgroup A1 or subgroup A2a or A2b, alternatively from both subgroups A1 and A2a or A2b. In another embodiment, the combination comprises the pre- and post-fusion F proteins derive from the genotype B, particularly from the subgroup B1 or subgroup B2, alternatively from both subgroups B1 and B2. In yet another embodiment, the combination comprises the pre- and post-fusion F proteins from the different genotypes A and B. In particular, the pre-fusion F protein derives from the subgroup A1 (or A2a or A2b) and the post-fusion F protein derives from the subgroup B1 (or B2). Alternatively, the pre-fusion F protein derives from the subgroup B1 (or B2) and the post-fusion F protein derives from the subgroup A1 (or A2a or A2b). More specifically, the compositions that are parts of the present invention, which comprise the combination of the pre-fusion and post-fusion F proteins are cited in Table 2.
In a further embodiment, the immunogenic composition of the present invention is able to provide protection against at least one, preferably against more than one hMPV strain selected from the group comprising NL/1/00, NL/17/00, TN/94-49, NCL174, CAN97-83, NL/1/9, NDL00-1, C1-334, CAN97-82 and TN/89-515. Particularly, the immunogenic composition of the present invention can provide protection against two or more strains that belong to different genotypes or different subgroups of one genotype. For instance, the immunogenic composition can provide protection against A1 and/or A2a and/or A2b subgroup(s), alternatively, against B1 and/or B2 subgroup(s), or against both A and B genotypes. Especially, cross-protection between A and B genotypes is desirable.
In a further embodiment, the present invention provides the pharmaceutical compositions comprising the combination of two recombinant F proteins available in the pre- and post-fusion conformation forms. Typically, the pharmaceutical composition further comprises at least one pharmaceutically acceptable carrier or excipient. Pharmaceutically acceptable carrier is used to formulate the hMPV F protein for clinical administration. Remington's Pharmaceutical Sciences, by E. W. Martin, Mack Publishing Co., Easton, PA, 19th Edition, 1995, describes compositions and formulations suitable for pharmaceutical delivery of the immunogen. In general, the nature of the carrier depends on the particular mode of administration being employed. For instance, parenteral formulations usually comprise injectable and physiologically acceptable fluids such as water, physiological saline, balanced salt solutions, aqueous dextrose, glycerol or the like as a vehicle. For solid compositions (e.g., powder, pill, tablet, or capsule forms), conventional non-toxic solid carriers can include, for example, pharmaceutical grades of mannitol, lactose, starch, or magnesium stearate. In addition to biologically neutral carriers, pharmaceutical compositions can contain minor amounts of non-toxic auxiliary substances, such as wetting or emulsifying agents, preservatives, and pH buffering agents and the like, for example sodium acetate or sorbitan monolaurate. In certain embodiments, the carrier suitable for administration to a subject is sterile, and/or suspended or otherwise contained in a unit dosage form containing one or more measured doses of the composition suitable to induce the desired anti-hMPV immune response. The unit dosage form may be, for example, in a sealed vial or a syringe for injection, or lyophilized for subsequent solubilization and administration or in a solid or controlled release dosage.
In some embodiments, the immunogenic composition (or vaccine) may further include an adjuvant. By adjuvant is meant any substance that is used to specifically or non-specifically potentiate an antigen-specific immune response, perhaps through activation of antigen presenting cells. Non-limiting examples of adjuvants include an aluminum salt (often referred to as “alum”) such as aluminium hydroxide or aluminium phosphate (as described in WO 2013/083726), an oil emulsion (such as complete or incomplete Freund's adjuvant), montanide Incomplete Seppic Adjuvant such as ISA51, a squalene-based oil-in-water emulsion adjuvants such as MF59® (Seqirus) (Ott G. et al. 1995. Pharm Biotechnol 6: 277-96), AddaVax™ (InvivoGen), monophosphoryl lipid A (MPL) (Cluff C W. 2010. Adv Exp Med Biol 667:111-23), Glucopyranosyl Lipid Adjuvant (GLA) (Coler RN et al. Development and characterization of synthetic glucopyranosyl lipid adjuvant system as a vaccine adjuvant. PLoS One. 2011, 6(1): e16333), polycationic peptide such as polyarginine (polyR) or a peptide containing at least two LysLeuLys motifs, especially KLKLLLLLKLK (described in WO 02/32451), immunostimulatory oligodeoxynucleotide containing non-methylated cytosine-guanine dinucleotides (CpG ODN), e.g., CpG1018 (Dynavax) (e.g., as described in WO 96/02555) or ODNs based on inosine and cytidine (I-ODN) such as polyIC (e.g., as described in WO 01/93903), or deoxynucleic acid containing deoxy-inosine and/or deoxyuridine residues (as described in WO 02/95027), especially oligo(dIdC)13 based adjuvant IC31® (Valneva SE) (as described in WO 2004/084938 and Olafsdottir et al. 2009. Scand J Immunol. 69(3): 194-202), neuroactive compound, especially human growth hormone (as described in WO 01/24822), a chemokine (e.g., defensins 1 or 2, RANTES, MIP1-α, MIP-2, interleukin-8, or a cytokine (e.g., interleukin-1β, -2, -6, -10 or -12; interferon-γ; tumor necrosis factor-α; or granulocyte-monocyte-colony stimulating factor), muramyl dipeptide (MDP) variants, non-toxic variants of bacterial toxins, QS-21 (Antigenics Inc.), Quill A, MTP-PE and others as described in Sarkar et al. (2019), as well as adjuvant systems such as AF03, AS01, AS03 and ASO4 (Giudice et al. 2018. Seminars in Immunology 39: 14-21). Usually, selection of a proper adjuvant depends on a type of B- or T-cell immune response desirable for a certain vaccine (Sarkar et al. (2019) Selection of adjuvants for vaccines targeting specific pathogens. Expert Rev Vaccines 18(5): 505-521). Generally, adjuvants that transduce immunological signals via TLR3, TLR4, TLR7, TLR8, and TLR9 receptors promotes Th1-biased immunity, while signaling via TLR2/TLR1, TLR2/TLR6 and TLR5 promotes Th2-biased immunity. For instance, such adjuvants as CpG ODN, polyIC and MPL predominantly induce Th1 responses, alum is a strong inducer of a Th2 response, while MF59®, AddaVax™, and IC31® induce mixed Th1 and Th2 responses. A preferred adjuvant useful in the vaccine of the present invention may be selected from, but not limited to, alum, CpG ODN such as CpG1018 (Dynavax), polyIC, IC31® (Valneva), MF59® (Seqirus), AddaVax™, AS03 (GSK), AS01 (GSK), QS21 (Pfizer), or combination(s) thereof, in particular, alum and CpG1018, alum and MPL, alum and IC31®, GLA-SE, 3M-052-alum, GLA-3M-052-alum. The aluminium adjuvant particularly useful in the current invention is an aluminium salt providing an aqueous immunogenic composition with less than 350 ppb heavy metal (such as Cu, Ni, W, Co, Os, Ru, Cd, Ag, Fe, V, Cr, Pb, Rb and Mo), especially less than 1.25 ppb copper (particularly, Cu+ or Cu2+), based on the weight of the aqueous immunogenic composition. In some embodiments, the aluminum adjuvant, especially the aluminium adjuvant comprising more than 1.25 ppb cooper or more than 350 ppb heavy metal, may be used in the combination with a radical quenching compound, such as L-methionine, present in a sufficient amount, particularly, in a concentration of at least 10 mmol/1 in the immunogenic composition. In some embodiments, the immunogenic composition comprising the aluminum adjuvant may further comprise a reactive compound selected from the group consisting of a redox active compound, a radical building compound, a stabilizing compound and a combination of any thereof, especially wherein the reactive compound is selected from the group consisting of formaldehyde, ethanol, chloroform, trichloroethylene, acetone, triton-X-100, triton-X-114, deoxycholate, diethylpyrocarbonate, sulfite, Na2S2O5, beta-propiolactone, polysorbate such as Tween 20®, Tween 80®, O2, phenol, pluronic type copolymers, and a combination of any thereof. An adjuvant may be formulated together with an antigen in one immunogenic composition or may be administered separately either by the same route as that of the antigen or by a different route.
In some embodiments, the immunogenic composition (or vaccine) disclosed herein may include one or more additional antigen(s), preferably a viral protein derived from hMPV, such as another F protein or a different hMPV protein. Presumably, inclusion of an additional hMPV protein into the F protein-based vaccine can provide an improved (more balanced and robust) immune response. Among different hMPV proteins, the M protein has been described as such that is able to modulate humoral and cellular immune responses (especially Th1/Th2 balance), thereby providing an adjuvant effect in mice when the M protein is combined with the F protein (Aerts et al. 2015. Adjuvant effect of the human metapneumovirus (HMPV) matrix protein in HMPV subunit vaccines. J Gen Virol. 96 (Pt 4): 767-774). Therefore, in one embodiment, the immunogenic composition described herein includes the recombinant hMPV M protein for increasing protection conferred by the vaccine. The recombinant M protein may comprise the amino acid sequence of SEQ ID NO: 41 or a fragment thereof, or a variant thereof having at least 80% sequence identity to the parent M protein. Preferably, the recombinant M protein of the present invention consists of the amino acid sequence of SEQ ID NO: 41.
The additional hMPV protein may be the surface glycoprotein G or the small hydrophobic protein SH. Despite the fact that antibodies induced against the G and SH proteins do not protect against hMPV infection in animal models (Skidopoulus et al. (2006) Individual contributions of the human metapneumovirus F, G, and SH surface glycoproteins to the induction of neutralizing antibodies and protective immunity. Virology 345:492-501; Ryder et al., (2010) Soluble recombinant human metapneumovirus G protein is immunogenic but not protective. Vaccine 28(25): 4145-4152), one can suggest that these antigens could contribute to the protection in humans. Furthermore, high degree of genetic diversity between the A and B genotypes for these proteins could become important for immunoprophylaxis, such that both genotypes would need to be represented in a vaccine.
In some embodiments, the additional antigen may be derived from another virus causing a respiratory tract infection, such as RSV (Respiratory Syncytial Virus), PIV3 (ParaInfluenza Virus type 3), influenza virus or a coronavirus (such as SARS-CoV, SARS-CoV-2, MERS or alike). For instance, the additional antigen may be the RSV F protein, PIV3 F protein, influenza hemagglutinin or coronavirus S-protein. Such immunogenic compositions (vaccines) would be protective against more than one virus, representing combinatorial vaccines against respiratory tract infections.
In a further embodiment, the composition of the present invention is an immunogenic composition or vaccine comprising at least two immunogenic hMPV F proteins, especially the combination of two F proteins available in the pre-fusion and post-fusion conformations. Typically, the immunogenic composition or vaccine is capable of eliciting an antigen-specific immune response to an immunogenic protein(s). The immune response may be humoral, cellular, or both. A humoral response results in production of F protein-specific antibodies by the mammalian host upon exposure to the immunogenic composition. F protein-specific antibodies are produced by activated B cells. Production of neutralizing antibodies depends on activation of specific CD4+ T cells. In addition, there is evidence that protection against hMPV infection may employ CD8+ T cells (CTL response) that cooperate synergistically with CD4+ T cells (Kolli et al. (2008) T Lymphocytes Contribute to Antiviral Immunity and Pathogenesis in Experimental Human Metapneumovirus Infection. JOURNAL OF VIROLOGY, September 2008, p. 8560-8569). Therefore, the immunogenic composition or vaccine of the present invention induces a measurable B cell response (such as production of antibodies) against the hMPV F protein and/or a measurable CTL response against the hMPV virus when administered to a subject.
According to the present invention, the immunogenic composition is able to elicit antibodies directed against both conformations of the F protein: the pre-fusion and post-fusion. Preferably, the anti-F protein antibodies are neutralizing antibodies able to interfere with the native F antigen existing in any (or both) conformation(s) and deactivate the virus. Most preferably, a neutralizing antibody response induced in the immunized subject is sufficient to combat an hMPV infection. A neutralizing antibody response may be measured in sera by ELISA and/or PRNT method or any other method known in the art.
Additionally, the immune response (e.g., neutralizing antibody titers) raised against the composition comprising two F proteins in the pre- and post-fusion conformations is superior to immune response (neutralizing antibody titers) elicited by the composition comprising a single (pre- or post-) F protein used at the same amount as in the composition comprising the combination disclosed herein. Moreover, a synergistic effect from combining two immunogenic F proteins in one composition make the immunogenic composition (or vaccine) more potent than a single-F protein composition (or vaccine) that may allow reducing a therapeutic or prophylactic dosage.
In one embodiment, the immunogenic composition or vaccine can reduce the severity of the symptoms associated with hMPV infection and/or decreases the viral load compared to a control in the subject upon administration. In another embodiment, the immunogenic composition or vaccine can reduce or prevent hMPV infection. In a preferred embodiment, the immunogenic composition or vaccine of the present invention can protect the immunized mammalian subject against hMPV infection.
Additionally, the immunogenic composition of the present invention is capable of providing protection against more than one hMPV strain, especially against different hMPV subgroups or genotypes. In one embodiment, the immunogenic composition can provide protection against viruses of the genotype A. In yet one embodiment, the immunogenic composition can provide protection against viruses of the genotype B. In a preferred embodiment, the immunogenic composition described herein is protective against both A and B genotypes. In particular embodiments, the immunogenic composition can provide protection against A1 and/or A2a and/or A2b subgroup(s), alternatively, against B1 and/or B2 subgroup(s), or against both A and B genotypes. In a preferred embodiment, cross-protection between the A and B genotypes is feasible.
In a further embodiment, the present invention includes combinations of the immunogenic composition or vaccine disclosed herein and a different hMPV vaccine or another respiratory vaccine, such as an anti-RSV, PIV3, influenza or coronavirus (such as SARS-CoV, SARS-CoV-2, MERS or alike) vaccine. Particularly, the combination may comprise the hMPV vaccine comprising the recombinant hMPV pre-/post-fusion F proteins and another subunit hMPV vaccine or an hMPV vaccine based on the whole virus or VLP particles. Additionally, the combination may comprise the recombinant hMPV F protein vaccine disclosed herein and an RSV vaccine, or the recombinant hMPV F protein vaccine and a PIV3 vaccine, or the recombinant hMPV F protein vaccine and an influenza vaccine, or the recombinant hMPV F protein vaccine and a coronavirus (especially, anti-SARS-CoV-2) vaccine. Preferably, the combination comprises the recombinant hMPV F protein vaccine disclosed herein and a recombinant RSV F protein vaccine. In one embodiment, the combination is understood as a combination of separate vaccine formulations administered simultaneously or subsequently by the same or different route. In another embodiment, two vaccines are combined in a single formulation.
In another embodiment, the immunogenic composition disclosed herein may be used as a medicament or vaccine, particularly in connection with a disease linked to or associated with hMPV infection, particularly for treating and/or preventing in a mammalian subject. Accordingly, the immunogenic composition (or vaccine) described herein is administered to a subject in a therapeutically effective amount. A therapeutically effective amount is the amount of a disclosed immunogen or immunogenic composition, that is sufficient to prevent, treat (including prophylaxis), reduce and/or ameliorate symptoms and/or underlying causes of a disorder or disease, for example to prevent, inhibit and/or treat hMPV infection. In some embodiments, a therapeutically effective amount is sufficient to reduce or eliminate a symptom of a disease, such as hMPV infection. For instance, this can be the amount necessary to inhibit or prevent viral replication or to measurably alter outward symptoms of the viral infection. In general, this amount will be sufficient to measurably inhibit virus replication or infectivity. Typically, a desired immune response inhibits, reduces or prevents hMPV infection. In one embodiment, the infection does not need to be completely eliminated, reduced or prevented for the method to be effective. For example, administration of a therapeutically effective amount of the agent can decrease the infection (as measured by infection of cells, or by number or percentage of infected subjects), for example by at least 10%, at least 20%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 98%, or even 100% as compared to a suitable control. In another embodiment, complete elimination or prevention of detectable hMPV infection is desirable.
The pharmaceutical composition (or vaccine) disclosed herein may be administered by any means and route known to the skilled artisan. In some embodiments, the compositions (vaccines) may be formulated for parenteral administration by injection. As used herein, “parenteral” administration includes, without limitation, subcutaneous, intracutaneous, intravenous, intratumoral, intramuscular, intraarticular, intrathecal, or by infusion. In some embodiments, the compositions may be formulated for mucosal (intranasal or oral) administration. Formulations for injection may be presented in unit dosage form, e.g., in ampoules or in multi dose containers, with an added preservative.
It is understood, that to obtain a protective immune response against hMPV can require multiple administrations of the immunogenic composition. Thus, a therapeutically effective amount encompasses a fractional dose that contributes in combination with previous or subsequent administrations to attaining a protective immune response. For example, a therapeutically effective amount of an agent can be administered in a single dose, or in several doses, for example daily, during a course of treatment (such as a prime-boost vaccination regimen). However, the therapeutically effective amount can depend on the subject being treated, the severity and type of the condition being treated, and the manner of administration. A unit dosage form of the agent can be packaged in a therapeutic amount, or in multiples of the therapeutic amount, for example, in a vial (e.g., with a pierceable lid) or syringe having sterile components.
According to the present invention, dosage regimens have to be adjusted in order to provide the optimal desired response. In general, effective doses of the compositions disclosed herein for the prophylactic and/or therapeutic treatment may vary depending upon many different factors, including means of administration, target site, physiological state of the patient, age, whether the patient is human or non-human, other medications administered, whether treatment is prophylactic or therapeutic, etc. According to the present invention, the amount of the F protein in the unit dose may be anywhere in a broad range from about 0.01 μg to about 100 mg. Particularly, the composition of the invention may be administered in the amount ranging between about 1 μg and about 10 mg, especially between about 10 μg to about 1 mg. Preferably, the antigen formulation dosages need to be titrated to optimize safety and efficacy.
In a further embodiment, the present invention provides methods for generating anti-hMPV immune response in a subject that comprises administering a therapeutically effective amount of the immunogenic composition to the subject of need. The method includes stimulating B cells for producing F protein-specific antibodies and cytokine-producing T helper cells in order to protect said subject from hMPV infection or associated disease. In some cases, such method may comprise a prime-boost administration of the immunogenic composition. A booster effect refers to an increased immune response to the immunogenic composition upon subsequent exposure of the mammalian host to the same or alike immunogenic composition. For instance, the priming comprises administration of the composition with the F proteins of the genotype A, while the boosting comprises administration of the composition with the F proteins from the genotype B, and vice versa. Alternatively, the prime-boost immunization employs the same composition (homologous boosting), especially the mixed composition comprising the F proteins of both genotypes A and B.
Furthermore, the method may comprise only a boost immunization with the immunogenic compositions comprising modified F proteins or variants thereof derived from the same or different hMPV genotypes (A and/or B) or subgroups (A1, A2a, A2b, B1 and/or B2) in particularly for elderly or adults (e.g. adults at risks) since most of these populations have already been exposed.
In yet further embodiment, the present disclosure provides methods for treating and/or preventing an hMPV infection in the subjects, which comprise administering to the subjects a therapeutically effective amount of the immunogenic composition to generate neutralizing antibodies and provide protection against hMPV of one genotype, A or B, preferably against hMPV of both genotypes, A and B.
In yet further embodiment, the present disclosure provides methods for producing the pharmaceutical (immunogenic) compositions, including vaccines, employed in the invention. The method comprises i) expressing the recombinant pre- or post-fusion F protein from the corresponding nucleic acid molecule inserted in an expression vector in a host cell, ii) purifying the recombinant F protein; and iii) combining the purified recombinant protein with a pharmaceutically acceptable carrier and/or excipient, optionally with an adjuvant.
The pharmaceutical (immunogenic) compositions of the invention, including vaccines, can be produced in accordance with methods well known and routinely practiced in the art (see e.g., Remington: The Science and Practice of Pharmacy, Mack Publishing Co. 20th ed. 2000; and Ingredients of Vaccines—Fact Sheet from the Centers for Disease Control and Prevention, e.g., adjuvants, enhancers, preservatives, and stabilizers). The compositions disclosed herein are preferably manufactured under GMP conditions. The compositions of the invention, including vaccines, are formulated into pharmaceutically acceptable dosage forms by conventional methods known to those of skill in the art.
The invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
The methods and techniques of the present disclosure are generally performed according to conventional methods well known in the art and as described in various general and more specific references that are cited and discussed throughout the present specification unless otherwise indicated. Although any methods and materials similar or equivalent to those described herein can be used in the practice of the present invention, the preferred methods, and materials are described herein.
The present invention is further illustrated by the following Examples, Figures, Tables and the Sequence listing, from which further features, embodiments and advantages may be taken, but which in no way should be construed as further limiting.
The native hMPV F protein can be selected from any hMPV strain and any genotype represented by the sequences of SEQ ID NOs 1 to 10, or fragments, or variants thereof. In certain embodiments, the hMPV F protein derives from the strain NL/1/00, genotype A, subgroup A1, represented by SEQ ID NO: 1, the strain TN/94-49, genotype A, subgroup A2a, represented by SEQ ID NO: 4, the strain NCL174, genotype A, subgroup A2b, represented by SEQ ID NO: 2, the strain C1-334, genotype B, subgroup B1, represented by SEQ ID NO: 9, and the strain TN/98-515, genotype B, subgroup B2, represented by SEQ ID NO: 10.
The plasmid pVVS1371 used for cloning contains:
The coding sequence of the wild type F protein was isolated from the hMPV strain NL/1/00, subgroup A1 and was codon-optimized for expression in CHO cells. The coding sequences of the wild type and modified F proteins were cloned into pVVS1371 plasmid for transient or stable protein expression in CHO cells.
Briefly, the coding sequences were cloned between the chimeric intron and the bGH a polyadenylation site of the pVVS1371 vector using the restriction sites SalI and PacI. The vector and the synthetized coding sequence (synthesis was done by GeneArt) were digested with SalI and PacI before purification on an agarose gel. The fragments were ligated with T4 DNA ligase and the ligation product was used to transform Max efficiency DH5α competent cells. Selected clones were tested for designed mutations by sequence analysis.
The protein expression is based on transient transfection of CHO cells using a MaxCyte® STX Scalable Transfection System device and following experimental recommendations of the supplier. Briefly, prior to electroporation, CHO cells are pelleted, suspended in MaxCyte® electroporation buffer and mixed with corresponding expression plasmid DNA. The cell-DNA mixture is transferred to a cassette processing assembly and loaded onto the MaxCyte® STX Scalable Transfection System. Cells are electroporated using the “CHO” protocol preloaded in the device and immediately transferred to culture flasks and incubated for 30 to 40 minutes at 37° C. with 8% CO2. Following the recovery period, cells are resuspended at high density in EX-CELL ACF CHO medium (Sigma-Aldrich). Post-electroporation cell culture is carried out at 37° C., with 8% CO2 and orbital shaking.
The production kinetics consist of decreasing the culture temperature to 32° C. and feeding the transfected cells daily with a fed-batch medium developed for transient protein expression in CHO cells (CHO CD EfficientFeed™ A (ThermoFischer Scientific), supplemented with yeastolate, glucose and glutaMax). After about 7 to 14 days of culture, cell viability is checked and conditioned medium is harvested after cell clarification corresponding to two runs of centrifugation at maximum speed for 10 minutes. Clarified product is filtered through a 0.22 m sterile membrane and stored at −80° C. before protein purification.
At day 7 post transfection, cells are washed once in PBS and fixed for 10 minutes in 4% paraformaldehyde at room temperature. Fixed cells are permeabilized in BD Perm wash for 15 minutes at room temperature and incubated with the primary antibody diluted in BD Perm wash for 1 hour at 4° C. Finally, a secondary antibody coupled to a fluorescent marker is added for 1 hour at 4° C. and stored in PBS at 4° C. until analysis by flow cytometry (MacsQuant Analyzer, Miltenyi Biotec). As the primary antibody the MPE8 N113S antibody (PRO-2015-026-01) specifically recognizing the pre-fusion conformation of the hMPV F protein, or the DS7 IgG1 antibody (PRO-2016-003) recognizing both pre- and post-fusion hMPV F protein have been used. The fluorescent FITC-conjugated secondary antibody was goat anti-mouse IgG+IgM (IR 115-096-068).
Frozen supernatant is brought to a room temperature and dialyzed with a standard grade regenerated cellulose dialysis membrane Spectra/Por® 1-7 CR (MWCO: 3.5 kDa) (Spectrum) against PBS. Subsequently, it is equilibrated with 50 mM Na2HPO4 buffer at pH 8.0, 300 mM NaCl and purification of the protein is performed using Immobilized Metal ion Affinity Chromatography (IMAC) followed by gel filtration chromatography.
For IMAC, agarose resin containing Ni2+ (His GraviTrap) is packed into chromatography columns by the manufacturer (GE Healthcare). The resin is washed with two volumes of deionized water and equilibrated with three volumes of equilibration and wash buffer (20 mM sodium phosphate, pH 7.4, with 0.5 M sodium chloride and 20 mM imidazole) as indicated by the manufacturer. After sample loading the column is washed with 10 mL of wash buffer. The His-tagged protein is eluted from the column using 3-10 column volumes of elution buffer as indicated by the manufacturer (50 mM sodium phosphate, pH 8.0, with 0.5 M sodium chloride and 500 mM imidazole). Eluate is then filtered on a 0.22 μm filter and dialyzed twice in Slide-A-lyzer™ Dialysis cassettes against a storage buffer (50 mM Na2HPO4, 300 mM NaCl, 5 mM EDTA, pH 8.0) before being aliquoted and stored at −20° C. Analysis of the purity, size and aggregation of the recombinant proteins is performed by size exclusion chromatography (SE-HPLC) and SDS-PAGE SE-HPLC (Shimadzu) is run on the column SUPERDEX200 (GE Healthcare).
Medium binging plates (Greiner) are coated with the human IgG1 DS7 capture antibody (Williams et al., 2007) at 200 ng/well and incubated overnight at 4° C. After 3×washing with water, the plates are saturated for 2 hours at 37° C. with PBS 0.05% Tween 20 and 5% dried-skimmed milk under agitation (saturation buffer). The liquid is removed from the wells and after 3×washing with water plates are incubated for 1 hour at 37° C. with 2.5 ng/well of the purified proteins of interest diluted in the saturation buffer. After washing, 5-fold serial dilution in saturation buffer of mouse antibody MPE8 N113S (Corti et al., 2013) directed against pre-fusion hMPV F protein or mouse antibody MF1 (Melero, personal communications) directed against post-fusion hMPV F protein are incubated for 1 hour at 37° C. Then the immune complexes are detected by incubation for one hour at 37° C. with secondary α-Ig species-specific antibody conjugated with peroxidase HRP Goat Anti-Mouse IgG (Covalab #lab0252) followed by 50 μL of peroxidase substrate (TMB, Sigma). The colorimetric reaction is stopped by adding 3 N H2SO4 and the absorbance of each well is measured at 450 nm with a spectrophotometer (MultiSkan).
Groups of five to ten BALB/c mice are immunized three times with two or three weeks interval (e.g. days 0, 14 or 21 and 28 or 42) subcutaneously with the recombinant pre- and post-fusion F proteins used alone or in different combinations in amounts from 0.02 to 6.0 μg per mouse with or without adjuvants. One to four weeks after the last immunization, blood is drawn by retro-orbital bleeding and sera are prepared. Evaluation of the immune response is performed by indirect ELISA as described below.
The recombinant F protein is diluted in carbonate/bicarbonate buffer at pH 9.6, and 50 ng of the protein per well is added to 96-well high binding plate (50 μL/well, Greiner). The plates are incubated overnight at 4° C. The wells are saturated for 30 minutes at room temperature with 150 μL of PBS 0.05% Tween 20 and 5% dried skimmed milk (saturation buffer). The liquid is removed from the wells and plates are incubated for 1 hour at room temperature with 50 μL/well of the sera of immunized mice at different dilutions (5-fold serial dilution) in saturation buffer. After washing 3 times with PBS 0.05% Tween 20, the immune complexes are detected by incubation for one hour at room temperature with 50 μl of secondary anti-IgG1 or IgG2a mouse-specific antibody conjugated with peroxidase followed by 50 μL of peroxidase substrate (TMB, Sigma). The colorimetric reaction is stopped by adding orthophosphoric acid and the absorbance of each well is measured at 450 nm with a spectrophotometer (MultiSkan). As a read out, IC50 values are calculated for evaluating specific antibody titers.
It was demonstrated that upon mice immunization with the pre- and post-fusion F protein vaccine, both pre-fusion and post-fusion F protein specific antibodies were generated.
Neutralizing antibody provides the best evidence that protective immunity has been established, and the biological assay of neutralization shows correlation with protection (Hombach et al., 2005).
It was assumed that by combining in the composition two F proteins (e.g., in the pre- and post-fusion conformations) of different genotypes A and B, cross-protection against a heterologous hMPV strain could be achieved. This hypothesis was tested as described below.
The hMPV virus of A1 (strain NL/1/00), A2a (strain TN/94-49), B1 (strain C1-334 or CAN97-82) or B2 (strain TN/89-515) subgroup, was propagated in LLC-MK2 cells (ATCC CCL-7) as described previously (Williams et al. 2005. The cotton rat (Sigmodon hispidus) is a permissive small animal model of human metapneumovirus infection, pathogenesis, and protective immunity. Journal of virology 79:10944-10951), and it was used in animal challenge experiments.
BALB/c mice are immunized three times with two weeks interval with adjuvanted recombinant F protein, as described previously, two weeks post-immunization they are challenged intranasally with around 1×106 pfu of the hMPV. Four to five days later, the animals are sacrificed and individual serum samples are taken and frozen.
On day −1, LLC MK2 cells, which were grown in OptiMEM containing 2% fetal bovine serum (FBS) and 1% antibiotic-antimycotic (Anti-Anti), are seeded into flat-bottom 96-well plates with a density of 2×105 cells/mL (100 μL/well) and incubated at 37° C./5% CO2 overnight.
On day 0, the serum samples are diluted in OptiMEM containing 100 μM CaCl2 and 1% Anti-Anti in U-bottom 96-well plates. As the sample dilutions are 1:1 mixed with the virus afterwards, 2× concentrated dilutions should be prepared. In control wells, without virus, medium is added instead of 2× concentrated virus dilution.
The dilutions of the hMPV A1 virus are prepared in OptiMEM medium containing 100 μM CaCl2 and 1% Anti-Anti in U-bottom 96-well plates. As the virus dilutions are 1:1 mixed with the diluted serum samples afterwards, the virus samples are prepared 2× concentrated (i.e. 120 pfu/60 μL). Blank wells are filled with the medium. The hMPV A1 virus is a trypsin-independent strain. For the hMPV B1 virus and all other trypsin-dependent hMPV strains, tryspin (i.e. TrypLE) is added to the medium to help the infection, ranging from 8 to 50 mrPu/mL according to serum concentration.
For the neutralization, an equal volume (60 μL) of the serum dilution and virus dilution is mixed (final concentration of the virus is 120 pfu/120 μL) and samples are incubated at room temperature for one hour. The flat-bottom 96-well plates containing the LLC MK2 cells are washed once with 150 μL/well PBS. Then 100 μL of the pre-incubated serum:virus mixtures are transferred to the 96-well plates covered with LLC MK2 cells and incubated at 37° C./5% CO2 for five days.
On day 5, 150 μL/well neutral-buffered formalin solution is added and the plates are incubated at room temperature for 1 hour. Then the plates are washed twice with 300 μL/well PBS and aspirated. 100 μL/well permeabilization buffer (PBS containing 0.5% Tween® 20) are added and the plates are incubated at 4° C. for 30 minutes. After aspiration of the permeabilization buffer, 100 μL/well blocking buffer (PBS containing 0.5% Tween® 20 and 10% skim milk) are added and the plates are incubated at 4° C. for 1 hour. The HRP-conjugated antibody (DS7 mIgG2a) is diluted in the blocking buffer (see above) to a concentration of 0.5 μg/mL and after aspiration of the blocking buffer 50 μL/well of the antibody solution is added. The plates are incubated at 37° C./5% CO2 for one hour followed by washing six times with 200 μL/well PBS using an ELISA washer. Then 100 μL/well TMB substrate is added and the plates are incubated at the room temperature for approximately 10 minutes. The reaction is stopped with 50 μL/well 1 M sulfuric acid and the absorbance is measured at 450 nm.
For studying the pre-/post-fusion F protein combinations, the pre-fusion L7F_A1_23 or L7F_B1_23 candidate and the post-fusion sF_A1_Mfur or sF_B1_Mfur candidate were selected. The recombinant proteins were produced from hMPV strains of different subgroups and genotypes. The following compositions (combinations) of the pre- and post-fusion F proteins were tested for induction of hMPV neutralizing antibodies (see, Table 3):
In six experiments performed in mice (see Table 4), each mouse was immunized either with the single F protein or with the combination vaccine. Mouse sera were used for testing neutralizing antibody titers performed by micro-neutralization assay (MNA) as described above. The results of these experiments are demonstrated in
The data shown in
The results shown in
Protection of mice upon immunization with the different pre-/post-fusion F protein compositions was evaluated in a mouse lung infection model.
BALB/c mice are immunized three times with two weeks interval with adjuvanted recombinant F protein, as described previously, two weeks post-immunization they are challenged intranasally with around 1×106 pfu of the hMPV. Four to five days later, the animals are sacrificed and lungs are taken and frozen. Lung tissue samples are harvested, weighed and homogenized in 1 mL medium for determination of viral load. Viral load in lung tissues is determined by virus foci immunostaining, as described below. Additionally, RT-qPCR is used to determine a viral load in the lungs.
The assay for hMPV foci quantification was developed based on the methods published in Williams et al., 2005. J Virology 79(17):10944-51; Williams et al., 2007. J Virology 81(15):8315-24; and Cox et al., 2012. J. Virology 86(22):12148-60. Briefly, confluent cultures of Vero cells or LLC-MK2 cells in 24-well plates are infected with 125 μL/well of lung homogenate diluted in medium. After 1 hour incubation at 37° C./5% CO2, overlay containing 1.5% methylcellulose in medium is added. At day 6 post-infection, the supernatant is removed and the cells are washed twice with PBS. Cell monolayers are fixed and stained with the DS7 antibody (mouse IgG2a). Foci are counted and cell images are captured with a Zeiss microscope using a 2.5× or 10× objective or using a BioReader 6000. Results of the immunostaining are expressed as focus forming units per milliliter, or FFU/mL.
RNA is extracted from 140 μL lungs homogenates using the QIAamp Viral RNA Mini Kit following the manufacturer's instruction and the RNA is eluted in 60 μL. RT-qPCR is performed using the iTaq™ Universal Probes One-Step Kit (Bio-Rad). For amplification of the N gene the following primers (e.g. forward 5′-CATATAAGCATGCTATATTAAAAGAGTCTC-3′ and reverse 5′-CCTATTTCTGCAGCATATTTGTAATCAG-3′) and probe (e.g. FAM-TGYAATGATGAGGGTGTCACTGCGGTTG-BHQ1) are used. The reaction volume for RT-qPCR is 20 μL using 400 nM of each primer, 200 nM probe and 4 μL RNA. Revers transcription and amplification is performed using the CFX96 Touch Deep Well Real-Time PCR System (Bio-Rad) with the conditions listed in Table 5.
The amount of hMPV RNA is calculated to a known full-length hMPV RNA standard with known concentration included in each run using the program Bio-Rad CFX maestro.
As used herein, clearance or reduction of hMPV infection may be determined by any method known in the art. In some embodiments, a level of hMPV infection in the subject is determined, for example, by detecting the presence of the virus by real time reverse transcription quantitative polymerase chain reaction (RT-qPCR).
The first question addressed in this study is to compare protection efficacy after vaccination with the composition comprising the recombinant single F protein used either in the pre-fusion or post-fusion forms vs. a composition comprising the combination of pre- and post-fusion F proteins. The second addressed question is to evaluate the optimal antigen dose of the composition containing the combination of the pre-/post-fusion F proteins. The third question to be addressed herein is establishing a cross-protection between different hMPV genotypes and/or subgroups.
To assess protection efficacy, mice immunized with any composition shown in Table 4 were challenged with the strain TN/94-49 (A2a subgroup) or C1-334 (B1 subgroup).
To evaluate a level of protection, the lung infection was assessed by FFA and RT-qPCR methods. The results are shown in
The different combinations shown in Table 4 at doses of 40 ng, 120 ng and 400 ng were tested in challenge experiments with either A2a strain or B1 strain, and the results are demonstrated in
BALB/c mice were immunized three times with two weeks interval with adjuvanted recombinant F protein vaccine, as described previously. Two weeks after the last immunization, blood was drawn by retro-orbital bleeding and sera were prepared. Evaluation of the immune response was performed by micro-neutralization assay (MNA) as described above.
For studying an adjuvanticity effect on the efficacy of the hMPV vaccine, one exemplary combination of the pre-/post-fusion F proteins L7F_A1_23 and sF_A1_Mfur was tested.
Mice were immunized with three doses of the compositions as shown I Table 6. Afterword, mice were challenged with hMPV strain, genotype subgroup A1. Sera were taken and used in the MNA assay for assessment of neutralizing antibody titers.
As the result, all tested adjuvants demonstrated enhancement of production of neutralizing antibodies against the homologous hMPV in mice. At the same time, no neutralizing antibodies could be detected in the absence of adjuvants. The combination of pre- and post-fusion F proteins formulated with the adjuvants alum+MPL and IC31high+alum generated the highest amount of neutralizing antibodies. A bit weaker effect was observed for the compositions with 3M-052-Alum and Addavax™. The results are shown in
From these experiments none of the tested adjuvant can be excluded from further testing in other animal species and humans.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21167609 | Apr 2021 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/059502 | 4/8/2022 | WO |
