Molecular evolution of influenza B virus during 2011\u20132017 in Chaoyang, Beijing, suggesting the free influenza vaccine policy

Na Lei,Yu-Song Zhang,Yuan-Jie Wang,Qiang Sun,Shu-Ming Li,Hai-Bin Wang,Jian-Hong Zhao,Yue-Long Shu,Lei Yang,Li-Yong Huang,Jian-Xin Ma,Ling-Li Sun,Yi Zhong

doi:10.1038/s41598-018-38105-1

Abstract

Two influenza B virus lineages, B/Victoria and B/Yamagata, are co-circulating in human population. While the two lineages are serologically distinct and TIV only contain one lineage. It is important to investigate the epidemiological and evolutionary dynamics of two influenza B virus lineages in Beijing after the free influenza vaccine policy from 2007. Here, we collected the nasopharyngeal swabs of 12657 outpatients of influenza-like illness and subtyped by real-time RT-PCR during 2011–2017. The HA and NA genes of influenza B were fully sequenced. The prevalence is the highest in the 6–17 years old group among people infected with influenza B. Yamagata-lineage virus evolved to two inter-clade from 2011–2014 to 2014–2017. The amino acids substitutions of HA1 region were R279K in strains of 2011–2014 and L173Q, M252V in strains of 2014–2017. Substitutions L58P, I146V were observed in HA1 region of Victoria-lineage virus in 2011–2012 and I117V, N129D were showed in 2015–2017. Phylogenetic analysis of NA showed Yamagata-Victoria inter-lineage reassortant occurred in 2013–2014. Influenza B mainly infect the school-aged children in Beijing and the free influenza vaccine inoculation does not seem to block school-age children from infection with influenza B. The antigen characteristics of circulating influenza B were different to the recommended vaccine strains. We concluded that the Victoria-lineage vaccine strain should been changed and the free influenza vaccine should be revalued.

Highlights

Influenza B was first isolated in 1940, designated as influenza B/Lee/40 and was classified into two distinct lineages by the genetically relationship of the hemagglutination assay (HA) gene, represented by the prototype viruses B/Victoria/2/87 (Victoria-lineage) and B/Yamagata/16/88 (Yamagata-lineage) since 19839–11
In this study we described the epidemiology and phylodynamics of influenza B viruses during 2011–2017 surveillance seasons in Chaoyang District in Beijing
The finding is consistent to the surveillance data of influenza B virus during 2009–2014 seasons in Shanghai and results from several community-based cohort studies that found that children were more frequently infected with B viruses than adults[22]

Summary

Introduction

Influenza B was first isolated in 1940, designated as influenza B/Lee/40 and was classified into two distinct lineages by the genetically relationship of the HA gene, represented by the prototype viruses B/Victoria/2/87 (Victoria-lineage) and B/Yamagata/16/88 (Yamagata-lineage) since 19839–11. Some studies said low level of cross-protection provided by immunization with vaccine containing antigen from a single influenza B lineage[14,15]. The continuous surveillance for influenza B in Beijing reflected the relationship between influenza vaccination rate and immune protective effect which imperative and has economic significance. The aim of this retrospective surveillance during the 2011–2017 seasons in Beijing was to assess the epidemiological and phylogenetic characteristics of influenza B from outpatients with influenza-like illness (ILI), and analyze the mismatch ratio between the circulating and vaccine strains

Methods

Results

Conclusion