Genetic variations and epidemiological characteristics of influenza B virus in Xinxiang from 2012 to 2019 / 中华疾病控制杂志

ABSTRACT

Objective To investigate the genetic variation and epidemiological characteristics of influenza B virus in Xinxiang to provide policy basis for local influenza vaccination. Methods The influenza surveillance data in Xinxiang from January 2012 to February 2019 was analyzed. 23 isolated influenza B virus were randomly selected for hemagglutinin (HA) and neuraminidase (NA) gene sequencing. Sequence alignment was conducted by using DNAman software and phylogenetic tree analysis was conducted using Neighbor-Joining method. Results Yamagata (BY) and Victoria (BV) strains of influenza B virus circulated alternately every other year in Xinxiang, mainly among people aged 0-15 years (91.4%). The dominant influenza B lineages from 2015 to 2016 and from 2017 to 2018 did not match the corresponding trivalent vaccine strain of the year. The HA phylogenetic tree revealed that 87.5% (7/8) of BV strains coexisted with the vaccine strain in one branch, while 88.98% (8/9) of BY strains from 2013 to 2015 were not in the same branch as the corresponding vaccine strain, with 5 epitope site mutions N116K, S150L, N165Y, D196N and N202S. No drug-resistant site mutation was identified in the NA gene. A total of 6 intra-lineage reassortants were identified. Conclusions The influenza B lineage in the trivalent vaccine recommended by WHO did not match the dominant circulating B lineage of Xinxiang in some epidemic year. Therefore, quadrivalent vaccines are recommended to use in susceptible population, especially under the age of 15. In addition, there are large variations in HA gene of the epidemic BY strain compared with the corresponding vaccine. Then, a vaccine more sutable for the epidemic strains in China is expected to be developed.