Influenza virus reassortment

A non-naturally occurring reassortant influenza A virus comprising six backbone viral segments, a hemagglutinin (HA) segment and a neuraminidase (NA) segment, wherein the virus comprises backbone segments from two or more donor strains, each donor strain providing more than one backbone segment, further wherein at least one backbone viral segment comprises a nucleotide sequence (a) having at least 95% identity to a sequence selected from the group consisting of SEQ ID NOs:

• 9-14 or SEQ ID NOs:
• 17-22, or (b) that encodes a viral polypeptide having at least 99% sequence identity with an amino acid sequence of a polypeptide encoded by the groups consisting of SEQ ID NOs 9-14 or SEQ ID NOs:
• 17-22;
• wherein the reassortant influenza A virus comprises PB1 and PB2 viral segments from the same donor strain and (1) the PB1 viral segment comprises a nucleotide sequence that encodes a viral polypeptide comprising the amino acid sequence of a polypeptide encoded by SEQ ID NO:
• 18 and (2) the PB2 viral segment comprises a nucleotide sequence that encodes a viral polypeptide comprising the amino acid sequence of a polypeptide encoded by SEQ ID NO:
• 19.