Identification of the Key Amino Acid Mutations in the PB2 and PA Proteins of Classical Swine H1N1 Influenza A Virus in Mammalian Adaptation
The classical swine (CS) H1N1 influenza virus firstly isolated in 1930 is highly homologous to the 1918 Spanish influenza virus. CS H1N1 virus crossed the interspecies barrier t...