Analysis of the prevalence characteristics and hemagglutinin gene variations of influenza type B virus in Putian City from 2018 to 2023
Objective To analyze the epidemiological characteristics and hemagglutinin(HA)gene variations of influenza B virus in Putian City from 2018 to 2023,provide a basis for optimizing local in-fluenza control strategies.Methods A total of 20,487 samples of influenza-like illness were collected from sentinel hospitals in Putian from January 2018 to December 2023.Influenza virus nucleic acids were detected using fluorescent PCR.Positive samples were identified and differentiated into Victoria and Yamagata sub-types.Full-length HA genes from 108 specimens were sequenced,and phylogenetic trees were constructed to analyze genetic variations.Results A total of 1470 cases of influenza B were detected,with a positive rate of 7.18%(1470/20 487).The Victoria subtype accounted for 86.39%(1270/1470),and the Yamagata subtype accounted for 13.61%.There is a statistically significant difference in the positive rate of COVID-19 among dif-ferent years(P<0.05).Influenza B is mainly prevalent in winter,spring,and summer,and the difference in positive rates among different seasons is statistically significant(P<0.05).The difference in positive rates among different age groups is statistically significant(P<0.05),with the highest positive rate in the population aged 5-14(13.09%).Evolutionary tree analysis revealed that the Victoria strain mainly belongs to the V1A.3 branch(46.43%,39/84),while the Yamagata strain belongs to the Y3 branch.Multiple amino acid mutations in the HA protein are concentrated in key antigenic epitope regions(120 loop,150 loop,160 loop,and 190 he-lix).Conclusions Influenza B in Putian exhibits a bimodal seasonal pattern,peaking in winter-spring and summer,with adolescents being the key target group for control.The V1A.3 branch of the Victoria subtype is predominant,and continuous HA gene variations may affect current vaccine efficacy,necessitating dynamic monitoring and timely updates of vaccine components.This study elucidates the epidemiological patterns and vi-ral evolution of influenza B in Putian,providing critical insights for influenza control and vaccine development.
Influenza B virusHAMolecular evolutionEpidemiology
NETL
NSTL
万方数据
