Live attenuated H1N1 influenza vaccine based on mutated M gene

Influenza vaccines currently approved for clinical use mainly include inactivated influenza virus vaccines and live attenuated influenza vaccines (LAIV). LAIV has multiple advantages such as ease of use, strong immunogenicity, and can provide cross-protection. In this study, the M gene of PR8 virus was mutated as follows (G11T, C79G, G82C, C85G, and C1016A), and live attenuated influenza virus containing the mutated M gene was rescued and obtained by reverse genetic technology as vaccine candidates. The replication ability of the rescued virus was significantly weakened in both MDCK cells and mice with attenuated virulence. Studies on immunogenicity found that 1,000TCID50 of mutated PR8(mPR8) can prime strong humoral and cellular immune responses. Single-dose immunization of 1,000TCID50 mPR8 was not only able to counter the challenge of homologous PR8 virus, but also provided cross-protection against heterologous H9N2 virus.