Influenza virus vaccine and uses thereof

1. A polypeptide comprising:

a. an influenza hemagglutinin HA1 domain that comprises an HA1 N-terminal stem segment covalently linked to a linker of 1 to 50 heterologous residues that is in turn covalently linked to an HA1 C-terminal short stem segment; said HA1 domain in tertiary or quaternary association with

b. an influenza hemagglutinin HA2 domain;

wherein the HA1 N-terminal stem segment consists of amino acid residues corresponding approximately to amino acids HA1 N-term through A p of an HA1 domain and the HA1 C-terminal short stem segment consists of amino acid residues corresponding approximately to amino acids B q through HA1 C-term of an HA1 domain, wherein HA1 N-term is the N-terminal amino acid of the HA1 domain, wherein HA1 C-term is the C-terminal amino acid of the HA1 domain, wherein A p is Cys that corresponds to amino acid position 52 of an HA1 using H3 numbering, wherein B q is Cys that corresponds to amino acid position 305 of an HA1 using H3 numbering, and wherein the polypeptide lacks an influenza virus hemagglutinin globular head domain.

2. The polypeptide of claim 1 , wherein the HA1 domain contacts the HA2 domain.

3. The polypeptide of claim 1 , wherein the HA1 C-terminal short stem segment is covalently linked to the HA2 domain.

4. The polypeptide of claim 1 that has a tertiary structure having 0-5 Á RMS deviation from the tertiary structure of the corresponding polypeptide of 1RUZ.

5. The polypeptide of claim 1 that selectively binds neutralizing antiserum capable of binding an influenza hemagglutinin.

6. The polypeptide of claim 1 , wherein:

(a) the amino acid sequences of the HA1 domain is at least 70%, 75%, 80%, 85%, 90%, 95%, 96% or 98% identical to the amino acid sequences of the corresponding domains of an HA1 from an H1, H2, H3, H4, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15 or H16 influenza A, and/or

(b) the amino acid sequence of the HA2 domain is at least 70%, 75%, 80%, 85%, 90%, 95%, 96% or 98% identical to the amino acid sequence of an HA2 from an H1, H2, H3, H4, H5, H6, H7, H8, H9, H10, H11, H12, H13, H14, H15 or H16 influenza A.

7. The polypeptide of claim 1 , wherein:

(a) the amino acid sequence of the HA1 N-terminal stem segment consists of a sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96% or 98% identical to residues 1-52 of an HA1 from an H3 influenza A;

(b) the amino acid sequence of the HA1 N-terminal stem segment consists of a sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96% or 98% identical to residues 1-46 of an HA1 from an H1 influenza A; or

(c) the HA1 N-terminal stem segment comprises a cysteine residue covalently linked to a cysteine residue of the HA1 C-terminal short stem segment via a disulfide bridge.

8. The polypeptide of claim 1 , wherein the HA1 N-terminal stem segment comprises the amino acid sequence A 17 -A 18 -(Xaa) n -A 38 (SEQ ID NO:146), wherein

A 17 is Y or H;

A 18 is H, L, or Q;

(Xaa) n represents a sequence of 18-20 amino acid residues; and

A 38 is H, S, Q, T or N.

9. The polypeptide of claim 1 , wherein said linker is of 1 to 40, 1 to 30 residues, 1 to 20 residues, 1 to 10 residues, 1 to 5 residues, 1 to 4 residues, 1 to 3 residues, 1 to 2 residues or 1 residue.

10. A virus comprising the polypeptide of claim 1 .

11. A viral-like particle comprising the polypeptide of claim 1 .

12. An immunogenic composition comprising the polypeptide of claim 1 .

13. An immunogenic composition comprising the viral-like particle of claim 11 and a pharmaceutically acceptable carrier.

14. A method of immunizing a subject comprising administering to the subject an effective amount of the immunogenic composition of claim 12 .

15. A method of immunizing a subject comprising administering to the subject an effective amount of the immunogenic composition of claim 13 .

16. A method of treating an influenza virus infection or an influenza virus disease comprising administering to a subject an effective amount of the immunogenic composition of claim 12 .

17. The polypeptide of claim 1 , wherein:

(a) the amino acid sequence of the HA1 C-terminal short stem segment consists of a sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96% or 98% identical to residues 305-326 of an HA1 from an H3 influenza A; or

(b) the amino acid sequence of the HA1 C-terminal short stem segment consists of a sequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96% or 98% identical to residues 306-327 of an HA1 from an H1 influenza A.

18. The polypeptide of claim 1 , wherein:

(a) the HA2 domain comprises the amino acid sequence A 18 -A 19 -A 20 -A 21 , wherein

A 18 is V or I;

A 19 is D, N or A;

A 20 is G, and

A 21 is W; or

(b) the HA2 domain comprises the amino acid sequence A 38 -A 39 -A 40 -A 41 -A 42 -A 43 -A 44 -A 45 -A 46 -A 47 -A 48 -A 49 -A 50 -A 51 -A 52 -A 53 -A 54 -A 55 -A 56 (SEQ ID NO:149), wherein

A 38 is K, Q, R, L or Y;

A 39 is any amino acid residue;

A 40 is any amino acid residue;

A 41 is T;

A 42 is Q;

A 43 is any amino acid residue;

A 44 is A;

A 45 is I;

A 46 is D;

A 47 is any amino acid residue;

A 48 is I, V or M;

A 49 is T, Q or N;

A 50 is any amino acid residue;

A 51 is K;

A 52 is V or L;

A 53 is N;

A 54 is any amino acid residue;

A 55 is V, I or L; and

A 56 is V or I.

19. The polypeptide of claim 1 , wherein said linker is selected from the group consisting of G n=2-5 , PG, ITPNGSIPNDKPFQNVNKITYGA of SEQ ID NO: 165, NAS and a direct bond.