Mutation and sequence analysis of influenza B virus hemagglutinin gene in Ningxia Hui Autonomous Region from 2017 to 2023
Objective To understand the etiological examination results and hemagglutinin(HA)gene mutations of influenza B virus in Ningxia Region.Methods Forty-four influenza B virus isolates were sampled using the spatiotemporal sampling method from Ningxia Hui Autonomous Region from 2017 to 2023.RNA was extracted from virus isolates,and HA gene fragment was amplified using real-time reverse-transcription PCR(RT-PCR)assay,followed by sequencing of the amplified products.In addition,the sequencing re-sults were subjected to bioinformatics analysis.Results Whole-genome sequencing of 44 influenza B virus isolates was performed.Mu-tations in antigenic sites were seen in 7 out of the 17BY lineage isolates relative to the B/California/12/2015 vaccine candidate,and there were R136G and L137H mutations in 120 antigenic epitopes,which all involved changes in receptor-binding sites.There were mu-tations in antigenic sites in 26 out of the 29 BV lineage isolates relative to theB/Colorado/06/2017vaccine candidate,which involved 11 receptor-binding sites in 4 antigenic epitopes.Mutations occurred in 3 receptor-binding sites,and no mutations were detected in potential glycosylation sites.All BY lineage virus isolates were clustered into the Clade 3,and all BV lineage virus isolates were clustered into the Clade 1A.Conclusions Influenza B continued to be prevalent in Ningxia Hui Autonomous Region from 2017 to 2023,and mutations occurred in antigenic sites.Intensified surveillance of influenza B is required.
Influenza B virusHemagglutininGene mutationAntigenic siteSequence analysis