[Influenza virus genome structure and encoded proteins].

Influenza A and B viruses each contain eight segments of ssRNA, and influenza C virus contains seven segments of ssRNA, with negative polarity. Each RNA segment encodes 1 or 2 proteins. The gene assignment for influenza A virus is as follows: RNA segment 1 codes for PB2, 2 for PB1, 3 for PA, 4 for HA, 5 for NP, 6 for NA, 7 for M1 and M2, and 8 for NS1 and NS2. M and NS genes of influenza A virus, NA, M, and NS genes of influenza B virus, and M and NS genes of influenza C virus encode two proteins. The terminal nucleotide sequences of individual RNA segments are the same within each type and also similar among different types, suggesting that A, B, and C viruses were derived from the same origin. Receptor recognition and receptor destroying proteins of A and B viruses, hemagglutinin(HA) and neuraminidase(NA), are similar in structure and character, but that of C virus, hemagglutinin-esterase(HE), is different.