Influenza hemagglutinin and neuraminidase variants

1. A 6:2 reassortant influenza virus, wherein said virus comprises 6 internal genome segments from A/Ann Arbor/6/60 and 2 surface antigen genome segments, wherein the surface antigen genome segments encode an HA and a NA polypeptide, wherein the surface antigen genome segment that encodes the HA polypeptide produces a polypeptide comprising the amino acid sequence of SEQ ID NO:29.

2. An immunogenic vaccine composition comprising an immunologically effective amount of the reassortant influenza virus of claim 1 .

3. A method for stimulating the immune system of an individual to produce a protective immune response against influenza virus, the method comprising administering to the individual an immunologically effective amount of the reassortant influenza virus of claim 1 in a physiologically effective carrier.

4. A method of prophylactic or therapeutic treatment of a viral infection in a subject, the method comprising: administering to the subject, the virus of claim 1 in an amount effective to produce an immunogenic response against the viral infection.

5. The method of claim 3 , wherein the individual is a human.

6. The method of claim 4 , wherein the subject is a human.

7. A live attenuated influenza vaccine comprising the composition of claim 2 .

8. A split virus or killed virus vaccine comprising the composition of claim 2 .

9. The method of claim 3 , wherein the virus is killed or inactivated.

10. The method of claim 4 , wherein the virus is killed or inactivated.

11. A method for producing an influenza virus in cell culture comprising:

i) introducing into a population of host cells, which population of host cells is capable of supporting replication of influenza virus, a plurality of vectors comprising nucleotide sequences corresponding to at least 6 internal genome segments of the influenza strain A/Ann Arbor/6/60; and, at least one genome segment encoding an HA surface antigen polypeptide wherein the surface antigen polypeptide comprises the amino acid sequence of SEQ ID NO:29;

ii) culturing the population of host cells at a temperature less than or equal to 35° C.; and

iii) recovering influenza virus.

12. An immunogenic composition comprising an immunologically effective amount of the influenza virus produced by the method of claim 11 .

13. A method for stimulating the immune system of an individual to produce a protective immune response against influenza virus, the method comprising administering to the individual an immunologically effective amount of the influenza virus produced by the method of claim 11 in a physiologically effective carrier.

14. A method for stimulating the immune system of an individual to produce a protective immune response against influenza virus, the method comprising administering to the individual the immunogenic composition of claim 12 .

15. A live attenuated influenza vaccine comprising the immunogenic composition of claim 12 .

16. A split virus or killed virus vaccine comprising the immunogenic composition of claim 12 .

17. The reassortant influenza virus of claim 1 , wherein the surface antigen genome segment that encodes the NA polypeptide produces a polypeptide comprising the amino acid sequence of SEQ ID NO:30.

18. The method of claim 11 , wherein the plurality of vectors further comprise a genome segment encoding an NA surface antigen polypeptide wherein the surface antigen polypeptide comprises the amino acid sequence of SEQ ID NO:30.