Genetic characterization of hemagglutinin gene of influenza A (H3N2) virus in Jingmen, Hubei, 2016−2023

Objective To investigate the genetic characteristics of hemagglutinin (HA) and antigen drift of influenza A (H3N2) virus in Jingmen, Hubei Province.

Methods A total of 60 strains of influenza A (H3N2) virus isolated in Jingmen from 2016 to 2023 were sequenced for whole genome. The antigenic variation and three-dimensional modeling of HA gene sequences were analyzed by using software MEGA 11 and UCSF Chimera 1.18.

Results From 2016 to 2023, influenza A (H3N2) virus were detected in 5 years in surveillance, and a total of six evolutionary clusters, including 3C.2a1, 3C.2a2, 3C.2a3, 3C.2a1b.1b, 3C.2a1b.2a.1a, 3C.2a1b.2a.2a.3a.1 were detected. Among them, 3C.2a2, predominated in 2016, and 3C.2a1b.2a.2a.3a.1, predominated in 2023, had 21 amino acid mutation loci in HA protein epitope and 13 amino acid mutation loci, including I140K, showed significant differences in the surface pattern structure diagram.

Conclusion Evolution and antigenic drift of influenza A (H3N2) virus occurred in Jingmen from 2016 to 2023. It is necessary to further strengthen the surveillance for molecular variation of influenza A (H3N2) virus.