Objective:To analyze the genetic characteristics of hemagglutinin（HA）and neuraminidase（NA）of influenza A（H1N1）pdm09 viruses in Kunming during the 2022-2023 influenza season.Methods:A total of 15 strains of A（H1N1）pdm09 influenza virus isolated from sentinel hospital surveillance and from outbreaks from April 2022 to March 2023 in Kunming were chosen for sequencing. The genetic analysis，which included sequence alignment，homology analysis，construction of phylogenetic tree and amino-acid mutations analysis，was carried out using MAFFT version 7，MegAlign and MEGA 11.Results:Fourteen strains isolated during the 2022-2023 influenza season in Kunming belong to clade 6B.1A.5a.2a，and A/Kunming/284/2023 belonged to clade 6B.1A.5a.2a.1. They all diverged from the northern hemisphere vaccine strain A/Wisconsin/588/2019 in clade 6B.1A.5a.2 recommended by WHO during the 2022-2023 influenza season. Comparing with the HA of the vaccine strain：A186T and Q189E，which might cause the reduction of vaccine protection，were identified in Sb of 14 strains；P137S，K142R in Ca and A186T，Q189E in Sb were identified in A/Kunming/284/2023 and two strains isolated from Thailand. The four mutations at tow antigenic sites identified immune escape at the molecular level. Q189E in the 190-helix and E224A in the 220-loop，which might change the pathogenicity of A（H1N1）pdm09 viruses，were identified in 15 strains. Comparing with NA of the vaccine strain：S200N in 14 strains and S339L in 1 strain were identified in antigenic sites. The two mutations might reduce the protection of antibodies induced by NA.Conclusion:Strengthening influenza surveillance and timely detecting new variants in Kunming contributes to preventing the importation of foreign strains and issuing early warnings for influenza outbreaks.

Objective:To analyze the genetic characteristics of hemagglutinin（HA）and neuraminidase（NA）of influenza A（H1N1）pdm09 viruses in Kunming during the 2022-2023 influenza season.Methods:A total of 15 strains of A（H1N1）pdm09 influenza virus isolated from sentinel hospital surveillance and from outbreaks from April 2022 to March 2023 in Kunming were chosen for sequencing. The genetic analysis，which included sequence alignment，homology analysis，construction of phylogenetic tree and amino-acid mutations analysis，was carried out using MAFFT version 7，MegAlign and MEGA 11.Results:Fourteen strains isolated during the 2022-2023 influenza season in Kunming belong to clade 6B.1A.5a.2a，and A/Kunming/284/2023 belonged to clade 6B.1A.5a.2a.1. They all diverged from the northern hemisphere vaccine strain A/Wisconsin/588/2019 in clade 6B.1A.5a.2 recommended by WHO during the 2022-2023 influenza season. Comparing with the HA of the vaccine strain：A186T and Q189E，which might cause the reduction of vaccine protection，were identified in Sb of 14 strains；P137S，K142R in Ca and A186T，Q189E in Sb were identified in A/Kunming/284/2023 and two strains isolated from Thailand. The four mutations at tow antigenic sites identified immune escape at the molecular level. Q189E in the 190-helix and E224A in the 220-loop，which might change the pathogenicity of A（H1N1）pdm09 viruses，were identified in 15 strains. Comparing with NA of the vaccine strain：S200N in 14 strains and S339L in 1 strain were identified in antigenic sites. The two mutations might reduce the protection of antibodies induced by NA.Conclusion:Strengthening influenza surveillance and timely detecting new variants in Kunming contributes to preventing the importation of foreign strains and issuing early warnings for influenza outbreaks.