Single endemic genotype of measles virus continuously circulating in China for at least 16 years.

Yan Zhang,Shunde Zhou,Shuang Wang,Yan Wang,Liwei Sun,Daxing Feng,Yan Liu,Paul A Rota,David Featherstone,Huiling Wang,Xiaodong Sun,Hui Gao,Yan Feng,Songtao Xu,William J Bellini,Zhen Zhu,Huanying Zheng,Xiaojie Zhang,Fangcai Li,Hong Tian,Leng Liu,Wenbo Xu,Shujie Zhou,Xueqiang Fang,Jiangtao Ma,Youngmee Jee,Yixin Ji,Wei Tang,Ying Hu,Zhenying Zhang,Suyi Gu,Jianfeng Liu,Changyin Wang,Chunyu Liu,Peishan Lu,Fang Bo,Shengwei Wu,Jian Zhou ,Shu Yuan ,Zhuang Ding ,Zhicong Yang ,Yu Ma

doi:10.1371/journal.pone.0034401

Abstract

The incidence of measles in China from 1991 to 2008 was reviewed, and the nucleotide sequences from 1507 measles viruses (MeV) isolated during 1993 to 2008 were phylogenetically analyzed. The results showed that measles epidemics peaked approximately every 3 to 5 years with the range of measles cases detected between 56,850 and 140,048 per year. The Chinese MeV strains represented three genotypes; 1501 H1, 1 H2 and 5 A. Genotype H1 was the predominant genotype throughout China continuously circulating for at least 16 years. Genotype H1 sequences could be divided into two distinct clusters, H1a and H1b. A 4.2% average nucleotide divergence was found between the H1a and H1b clusters, and the nucleotide sequence and predicted amino acid homologies of H1a viruses were 92.3%–100% and 84.7%–100%, H1b were 97.1%–100% and 95.3%–100%, respectively. Viruses from both clusters were distributed throughout China with no apparent geographic restriction and multiple co-circulating lineages were present in many provinces. Cluster H1a and H1b viruses were co-circulating during 1993 to 2005, while no H1b viruses were detected after 2005 and the transmission of that cluster has presumably been interrupted. Analysis of the nucleotide and predicted amino acid changes in the N proteins of H1a and H1b viruses showed no evidence of selective pressure. This study investigated the genotype and cluster distribution of MeV in China over a 16-year period to establish a genetic baseline before MeV elimination in Western Pacific Region (WPR). Continuous and extensive MeV surveillance and the ability to quickly identify imported cases of measles will become more critical as measles elimination goals are achieved in China in the near future. This is the first report that a single endemic genotype of measles virus has been found to be continuously circulating in one country for at least 16 years.

Highlights

Measles continues to be a leading cause of childhood morbidity and mortality in developing countries and an outbreak threat in the majority of countries, despite the availability of an effective vaccine for over 40 years [1]
The 3– 5 years measles epidemic cycles were possibly associated with the fluctuation of immunity coming from the combination of natural infection and vaccine-induced immunity
It is critical to determine the genetic baseline of Measles virus (MeV) in China before MeV elimination

Summary

Introduction

Measles continues to be a leading cause of childhood morbidity and mortality in developing countries and an outbreak threat in the majority of countries, despite the availability of an effective vaccine for over 40 years [1]. Molecular surveillance is most beneficial when there is continuous high quality surveillance and it is possible to observe the change in viral genotypes over time in a particular geographical region. Since this information can help to document the interruption of transmission of MeV, molecular surveillance can provide an important method to assess the effectiveness of vaccination programmes

Methods

Results

Conclusion