Yan Dongrei, Li Xiaolei, Zhang Yong, Yang Jianfang, Zhu Shuangli, Wang Dongyan, Zhang Chuangye, Zhu Hui, Xu Wenbo
Bing Du Xue Bao. 2015 Mar;31(2):157-63.
The World Health Organization redefined the type 2 vaccine-derived poliovirus (VDPV) in 2010. To study the genetic characteristics and evolution of type 2 VDPV under this new definition, we conducted genome sequencing and analyses of type 2 VDPVs isolated from one patient with acute flaccid paralysis in Shanxi province (China) in 2014. Nucleotide sequencing revealed that the full-length of type 2 VDPV is 7439 bases encoding 2207 amino acids with no insertion or deletion of nucleotides compared with Sabin2. One nucleotide substitution identified as a key determinant of the attenuated phenotype of the Sabin 2 strain (A-G reversion at nucleotide nt 481 in the 5-end of the untranslated region) had reverted in the Shanxi type 2 VDPV. The other known key determinant of the attenuated phenotype of the Sabin 2 strain (U-->C reversion at nt2909 in the VP1 coding region that caused a Ile143Thr substitution in VP1) had not reverted in the Shanxi VDPV. The Shanxi type 2 VDPV was S2/S1 recombinant, the crossover site of which mapped to the 3-end of the 3D region (between nt 6247 and nt 6281). A phylogentic tree based on the VP1 coding region showed that evolution of the Shanxi type 2 VDPV was independent of other type 2 VDPVs detected worldwide. We estimated that the strain circulated for approximately = 11 months in the population according to the known evolution rate. The present study confirmed that the Chinese Polio Laboratory Network could discover the VDPV promptly and that it played an important part in maintenance of a polio-free China.
2010年,世界卫生组织对2型疫苗衍生脊髓灰质炎病毒(VDPV)进行了重新定义。为研究在这一新定义下2型VDPV的基因特征及进化情况,我们对2014年从中国山西省一名急性弛缓性麻痹患者体内分离出的2型VDPV进行了基因组测序及分析。核苷酸测序显示,2型VDPV全长7439个碱基,编码2207个氨基酸,与Sabin2相比,核苷酸无插入或缺失。一个被确定为Sabin 2株减毒表型关键决定因素的核苷酸替换(5′非翻译区5′端第481位核苷酸A→G回复突变)在山西2型VDPV中发生了回复突变。Sabin 2株减毒表型的另一个已知关键决定因素(VP1编码区第2909位核苷酸U→C回复突变,导致VP1中第143位异亮氨酸替换为苏氨酸)在山西VDPV中未发生回复突变。山西2型VDPV为S2/S1重组型,重组交叉位点定位于3D区3′端(第6247位核苷酸与第6281位核苷酸之间)。基于VP1编码区构建的系统发育树显示,山西2型VDPV的进化独立于全球检测到的其他2型VDPV。根据已知的进化速率,我们估计该毒株在人群中传播了约11个月。本研究证实,中国脊髓灰质炎实验室网络能够及时发现VDPV,并且在维持中国无脊髓灰质炎状态方面发挥了重要作用。