Molecular characteristics and drug resistance analysis of H3N2 influenza virus in Jiangsu Province from 2022 to 2023
On the basis of the laboratory detection results of influenza viruses in Jiangsu Province from 2022 to 2023,this study was aimed at conducting a analysis of the genetic characteristics and resistance of the H3N2 influenza virus,and evalua-ting the effectiveness of vaccines and drugs.The full genome of 29 H3N2 isolates submitted by provincewide influenza surveil-lance network laboratories was amplified and sequenced.Phylogenetic trees of the HA and NA genes were constructed.The mutation characteristics of antigenic sites,glycosylation sites,and resistance sites were analyzed,and the influenza virus neura-minidase was detected with a fluorescence luminescence method.The homology of the 29 H3N2 isolates in Jiangsu Province was relatively high.The isolates belonged to the same evolutionary branch as domestic reference strains and the 2021-2022 vaccine strains,but were in different evolutionary branches from foreign reference strains and the 2022-2023 vaccine strains.Compared with the 2021-2022 vaccine strain A/Cambodia/e0826360/2020,the H3N2 influenza viruses isolated in Jiangsu Province during 2022-2023 had four amino acid substitutions in the HA protein and two amino acid substitutions in the NA protein.No changes in glycosylation sites,receptor-binding sites,and conserved amino acid residue regions were observed.IC50 analysis indicated that the 29 H3N2 isolates were not resistant to the antiviral drugs oseltamivir and zanamivir.The pre-dominant influenza viruses detected in Jiangsu Province during 2022-2023 were type A H3N2 influenza viruses.Monitoring of variations in HA and NA gene sites and influenza virus resistance aids in rapid understanding gene mutations,and can inform the selection of effective vaccine strains,and contribute to the prevention and control of influenza virus outbreaks.