Objective To analyze the genetic evolution characteristics and the anmino aicid sites variations of influenza A virus (H3N2) based on the neuraminidase genes in Hainan during 2019–2020.
Methods 16 strains of H3N2 virus isolated by Hainan Province Influenza Surveillance Network Laboratory were collected and the genomes were sequenced. The DNA Star 7.0.1 software were applied to analyze the neuraminidase gene similarities. The phylogenetic tree were constructed by MEGA 10.8.1 and sequence alignment were performed to analyze the drug resistant sites and antigenic determinants variants.
Results The NA gene similarity analysis and phylogenetic tree showed that all the analyzed H3N2 strains belonged to the 3c. 2a1 clade. The Nucleotide and amino acid similarities between the 16 strains of H3N2 viruses and vaccine strains A / Singapore/INFIMH-16-0019/2016 (2018-2019) were 98.5%-99.1%, 98.3%-98.7% respectively. Antigenic sites variations of NA occurred at N329S in 14 strains, and E344K in 11 strains. No amino acid substitutions on the drug resistance sites were detected.
Conclusion The H3N2 subtype virus prevailled in Hainan during 2019-2020 belonged to 3c. 2a1 clade. The genetic relationship was close to the 2018–2019 vaccine strains. The antigenic determinants in NA gene get changed but not obviously. The drug resistantance sites variation did not occur. We should further strengthen the surveillance analysis of influenza virus and pay more attention to the the drug resistance gene variationsto provide scientific evidence for the influenza viruse prevention and control.
摘要：目的分析海南省2019—2020年H3N2亚型流感病毒神经氨酸酶基因遗传进化特征与关键氨基酸位点变异 情况。 方法从海南省流感监测网络实验室分离的流感毒株中按照不同时间选取16株H3N2亚型分离株进行一代全 基因序列测定，应用DNA Star 7.0.1软件进行神经氨酸酶基因同源性分析，应用MEGA 10.8.1软件构建神经氨酸酶基因 系统进化树，并分析耐药性位点与抗原决定位点氨基酸替换情况。 结果神经氨酸酶基因同源性分析与系统进化分 析显示，16株分离株与疫苗株A/Singap。re/INFIMH-16-0019/2016(2018—2019)核苷酸与氨基酸相似性分别为98.5%~ 99.1%、98.3%~98.7%，进化上属于3c.2a1分支。14株分离株发生神经氨酸酶抗原性位点N329S变异，11株分离株发生 E344K变异，未发生耐药性位点氨基酸替换。 结论2019—2020年海南省流行的H3N2亚型流感病毒属于3c.2a1分 支，与2018—2019年疫苗株亲缘关系较近；大部分分离株在神经氨酸酶抗原决定位点发生了一定的改变，但变异程度 不大，未发生耐药位点变异。今后应持续加强流感病毒病原学监测，密切关注H3N2亚型流感病毒耐药性基因变异，及 时跟踪关键氨基酸位点替换情况，为科学防控提供理论依据。