Molecular epidemiology demonstrates that imported and localstrains circulated during the 2014 dengue outbreak in Guangzhou, China

Geng Li,Xiujuan Kong,Zhongde Zhang,Wei Zhang,Qiuyan He,Jianguo Wu,Huiting Huang,De Wu,Pan Pan,Xiaohong Liu,Jianbo Liu,Kailang Wu,Xiaoping Lai,Yuntao Liu

doi:10.1007/s12250-016-3872-8

Abstract

The dengue virus (DENV) is a vital global public health issue. The 2014 dengueepidemic in Guangzhou, China, caused approximately 40,000 cases of infection andfive deaths. We carried out a comprehensive investigation aimed at identifying thetransmission sources in this dengue epidemic. To analyze the phylogenetics of the2014 dengue strains, the envelope (E) genesequences from 17 viral strains isolated from 168 dengue patient serum samples weresequenced and a phylogenetic tree was reconstructed. All 17 strains were serotype Istrains, including 8 genotype I and 9 genotype V strains. Additionally, 6 genotype Istrains that were probably introduced to China from Thailand before 2009 were widelytransmitted in the 2013 and 2014 epidemics, and they continued to circulate until2015, with one affinis strain being found in Singapore. The other 2 genotype Istrains were introduced from the Malaya Peninsula in 2014. The transmission sourceof the 9 genotype V strains was from Malaysia in 2014. DENVs of different serotypesand genotypes co-circulated in the 2014 dengue outbreak in Guangzhou. Moreover, notonly had DENV been imported to Guangzhou, but it had also been gradually exported,as the viruses exhibited an enzootic transmission cycle in Guangzhou.

Highlights

Dengue virus (DENV) is a major health challenge in tropical and subtropical countries (Zellweger et al, 2010), Local DENV-1 circulated in Guangzhou more than 50–100 million DENV infections occur in over 100 countries annually, putting almost 2.5 billion people at risk (Costa et al, 2012).DENV is a single-stranded, positive-sense RNA virus that belongs to the family Flaviviridae
We verified that all 17 virus strains were DENV-1
Sang and colleagues analyzed the dengue epidemics in Guangzhou over the past 40 years and believe that they were caused by imported cases (Sang et al, 2015a)

Summary

Introduction

DENV is a single-stranded, positive-sense RNA virus that belongs to the family Flaviviridae. Its genome is approximately 11, 000 nucleotides, and encodes three structural proteins, including the C (core), M (membrane) and E (envelope) proteins; seven nonstructural proteins, including NS1, NS2a, NS2b, NS3, NS4a, NS4b and NS5 (Drumond et al, 2012); and short non-coding regions at both the 5′- and 3′-ends (WHO, 2009; Rodenhuis-Zybert et al, 2010). DENV can be grouped into five antigenically distinct serotypes (DENV-1, -2, -3, -4 and -5) (Wang et al, 2015) and each of these serotypes can be sub-classified into several genotypes based on their E gene sequences. Various genotypes have been epidemic in different geographic regions (Holmes and Burch, 2000). DENV-1, -2, -3 and -4 have been found and been prevalent in China

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Conclusion