Isolation and Characterization of a Type 2 Vaccine-Derived Poliovirus from Environmental Surveillance in China, 2012

Zexin Tao,Dongmei Yan,Yao Liu,Yong Zhang,Suting Wang,Shuangli Zhu,Hiromu Yoshida,Wenbo Xu,Ning Cui,Xiaojuan Lin,Ping Xiong,Lizhi Song,Aiqiang Xu,Haiyan Wang,Juan C De La Torre

doi:10.1371/journal.pone.0083975

Abstract

Environmental surveillance of poliovirus on sewage has been conducted in Shandong Province, China since 2008. A type 2 vaccine-derived poliovirus (VDPV) with 7 mutations in VP1 coding region was isolated from the sewage collected in the city of Jinan in December 2012. The complete genome sequencing analysis of this isolate revealed 25 nucleotide substitutions, 7 of which resulted in amino acid alteration. No evidence of recombination with other poliovirus serotypes was observed. The virus did not lose temperature sensitive phenotype at 40°C. An estimation based on the evolution rate of the P1 coding region suggested that evolution time of this strain might be 160–176 days. VP1 sequence analysis revealed that this VDPV strain is of no close relationship with other local type 2 polioviruses (n = 66) from sewage collected between May 2012 and June 2013, suggesting the lack of its circulation in the local population. The person who excreted the virus was not known and no closely related virus was isolated in local population via acute flaccid paralysis surveillance. By far this is the first report of VDPV isolated from sewage in China, and these results underscore the value of environmental surveillance in the polio surveillance system even in countries with high rates of OPV coverage.

Highlights

Polioviruses (PVs) have three serotypes and belong to the Enterovirus genus, Picornaviridae family
Since the live, attenuated oral poliovirus vaccine (OPV) is a main tool used in polio eradication efforts, rare paralytic poliomyelitis cases caused by VDPVs can occur when neurovirulence reverses as the result of mutations
VDPVs have the potential for sustained circulation in areas with low OPV coverage and many outbreaks of circulating VDPVs were reported worldwide in recent years [4,5]

Summary

Introduction

Polioviruses (PVs) have three serotypes and belong to the Enterovirus genus, Picornaviridae family Their infection is known to be associated with acute paralytic poliomyelitis. One is the re-emergence of WPV in previously polio-free countries, such as the WPV1 importation to mainland China in 2011 Another is the emergence of vaccine-derived polioviruses (VDPVs) (.1% divergent [PV1 and PV3] or .0.6% divergent [PV2]). Since the live, attenuated oral poliovirus vaccine (OPV) is a main tool used in polio eradication efforts, rare paralytic poliomyelitis cases caused by VDPVs can occur when neurovirulence reverses as the result of mutations. Most of the type VDPVs isolated from the field contain the G481A and U2909C mutation encoding a Ile to Thr substitution in VP1 These two mutations appear to be responsible for the neurovirulence reversion of the Sabin VDPVs [7]

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Conclusion