Subunit vaccine for treatment or prevention of a respiratory tract infection
The present invention relates to modified hMPV F proteins stabilized in the pre-fusion conformation as vaccine candidates.
1. An immunogenic human metapneumovirus (hMPV) modified F protein, comprising a recombinant single-chain polypeptide lacking a fusion peptide (FP), wherein the recombinant single-chain polypeptide comprises or consists of the amino acid sequence as set forth in SEQ ID NO: 56 or a variant thereof having at least 99% sequence identity thereto, wherein the immunogenic hMPV modified F protein comprises:
a) an F2 domain;
b) an F1 domain; and
c) a linker, wherein the linker i) is positioned between the F2 and F1 domains, ii) is 1 to 10 amino acids in length, and iii) contains a cysteine residue which forms a disulfide A bond with a non-natural cysteine residue present in the F1 domain.
2. The immunogenic protein of claim 1 , wherein the recombinant single-chain polypeptide further comprises a histidine or streptavidin tag for purification.
3. The immunogenic protein of claim 1 , wherein the immunogenic protein is a recombinant protein in a soluble form.
4. The immunogenic protein of claim 1 , wherein the immunogenic protein can form a homo- or hetero-trimer.
5. The immunogenic protein of claim 1 , wherein the immunogenic protein binds more strongly to the specific anti-pre-fusion MPE8 antibody than to the specific anti-post-fusion MF1 antibody.
6. The immunogenic protein of claim 1 , wherein the immunogenic protein is capable of eliciting neutralizing antibodies recognizing a native hMPV F protein.
7. An immunogenic composition or vaccine comprising the immunogenic protein of claim 1 .
8. The immunogenic composition or vaccine of claim 7 , further comprising an adjuvant.
9. The immunogenic composition or vaccine of claim 7 , further comprising an adjuvant that induces a mixed Th1/Th2 immune response.
10. The immunogenic composition or vaccine of claim 7 , further comprising at least one additional antigen.
11. A method for generating an immune response to a respiratory tract infection in a human subject, comprising administering to the subject an effective amount of the immunogenic protein of claim 1 .
12. A method for treating or preventing a respiratory tract infection in a human subject, comprising administering to the subject an effective amount of the immunogenic protein of claim 1 .
13. The immunogenic composition or vaccine of claim 8 , wherein the composition or vaccine further comprises a pharmaceutically acceptable carrier and/or excipient.
14. The immunogenic composition or vaccine of claim 8 , wherein the adjuvant comprises alum.
15. The immunogenic composition or vaccine of claim 9 , wherein the adjuvant comprises i) a squalene-based oil-in-water emulsion, ii) a combination of monophosphoryl lipid A (MPL) and alum, or iii) a combination of KLKLLLLLKLK (SEQ ID NO: 62) and oligo-(dIdC) 13 (SEQ ID NO: 63).
16. The immunogenic composition or vaccine of claim 10 , wherein the at least one additional antigen is derived from a respiratory virus.
17. The immunogenic composition or vaccine of claim 16 , wherein the at least one additional antigen is derived from a hMPV, a respiratory syncytial virus (RSV), a parainfluenza virus type 3 (PIV3), an influenza virus and/or a coronavirus.
18. The method of claim 12 , wherein the subject is at risk for or has at least one respiratory tract infection.
19. The method of claim 18 , wherein the at least one respiratory tract infection is an hMPV, a respiratory syncytial virus (RSV), a parainfluenza virus type 3 (PIV3), an influenza virus and/or a coronavirus infection.