Molecular evolutionary characteristics of H3N2 subtype influenza virus in Nantong City from 2022 to 2023
Objective To investigate the molecular evolutionary characteristics of H3N2 subtype influenza virus during influenza outbreaks in Nantong City in recent years.Methods Nasopharyngeal swab specimens were collected from influenza patients in Nantong City during influenza outbreaks from 2022 to 2023,and quantitative real-timePCR(qPCR)assay was performed test influenza virus nuclear acid.Viruses were isolated from specimens with Ct values of＜30,and the H3N2 virus isolates were subjected to high-throughput sequencing.Nucleotide and amino acid sequence alignments of HA and NA genes were performed,and phylogenetic trees were created.Results A total of 23 influenza outbreaks were reported,and all were caused by influenza A virus,including 12 out-breaks caused by H3N2 virus(52.17％)and 11 outbreaks caused by H1N1 virus(47.83％).Sequencing of 10 H3N2 virus isolates showed that the nucleotide sequence homology of HA and NA genes was 96.59％to 100.00％and 98.58％to 100.00％and the amino acid sequence homology was 96.13％to 100.00％and 96.40％to 100.00％,respectively.The nucleotide sequence homology of HA and NA genes was 96.62％to 97.38％and 96.87％to 97.36％and the amino acid sequence homology was 96.86％to 97.21％and 94.58％to 96.67％as compared to the influenza vaccine candidate A/Darwin/9/2021 recommended for use in the northern hemi-sphere by WHO.The major amino acid mutations in the HA gene included I156K,K187N,I208Fand G241D,with no mutations seen in RBS sites,and the major amino acid mutations in the NA gene included S331G and S150R/H,with conserved sites of action of neura-minidase inhibitors.Phylogenetic analysis revealed that 10 H3N2 virus isolates were clustered into 2a.3 and 3C.2alb.2b clades,which matched highly to the vaccine isolate.Conclusions H3N2 virus continues to evolve.Intensified surveillance is required to understand the evolutionary characteristics of influenza virus genes,so as to provide insights into precision containment of influenza.
Influenza AH3N2Homology analysisAmino acid mutation siteEvolutionary tree
NETL
NSTL
万方数据
