Influenza virus reassortment

A chimeric influenza hemagglutinin polynucleotide segment comprising an ectodomain, a 5′-non-coding region (5′-NCR), a 3′-non-coding region (3′-NCR), a signal peptide domain (SP), a transmembrane domain (TM), and a cytoplasmic domain (CT),

• wherein the ectodomain is from a first influenza strain which is an influenza A strain, and one or more of the 5′-NCR, 3′-NCR, SP, TM, and CT are from a second influenza strain selected from the group consisting of 105p30 and PR8-X, and
• wherein the 5′-NCR comprises SEQ ID NO:105 or SEQ ID NO:114, the 3′-NCR comprises SEQ ID NO:109 or SEQ ID NO:118, the SP comprises SEQ ID NO:106 or SEQ ID NO:115, the TM comprises SEQ ID NO:107 or SEQ ID NO:116, and the CT comprises SEQ ID NO:108 or SEQ ID NO:117.