中国急性弛缓性麻痹(AFP)病例中脊髓灰质炎病毒疫苗株VP1区基因变异的研究

Genomic Analysis of VP1 Region of Vaccine-associated Polioviruses from AFP Cases in China

为研究中国急性弛缓性麻痹 (AFP)病例中脊髓灰质炎 (简称脊灰 )病毒分离株的分子特征 ,为中国继续维持“无脊灰野毒状态”提供理论依据 ,对 2 0 0 2年所有省级疾病预防控制中心送检的脊灰分离株 ,用PCR RFLP法及ELISA法进行型内鉴定。用PCR RFLP法筛查出与疫苗株相比有异常酶切图谱的毒株共 2 4株 ,其中Ⅰ型毒株 1株 ,Ⅱ型毒株 2 1株 ,Ⅲ型毒株 2株 ;用ELISA法筛查出与疫苗株相比有不同的抗原抗体反应的毒株共 2 2株 ,其中Ⅰ型毒株 7株 ,Ⅱ型毒株 4株 ,Ⅲ型毒株 1 1株 ,在 7株Ⅰ型毒株中有 3株为非疫苗类似株 (NSL) ,其余为双反应毒株 (DRV)。随后对这 4 6株毒株进行了全VP1区的基因序列分析。结果表明 :2 0 0 2年脊灰分离株都是疫苗株或疫苗衍生株 ,没有发现野毒株 ,中国继续保持着“无脊灰野毒状态” ;口服减毒活疫苗 (OPV)株与其它野毒株在稳定性性质方面是类似的 ,即通常是不稳定的 ,在人体肠道内有很强的选择性 ;在人体肠道内 ,病毒复制产生的基因变异导致毒力升高 ,是引起疫苗相关麻痹病例 (VAPP)的重要原因 ,但宿主本身的因素也有很大的作用 ;在局部地区有疫苗株的循环或脊灰疫苗衍生株 (VDPV)的存在 ;最终消除疫苗株引起的AFP病例可能还需要脊灰灭活疫苗(IPV)的介入。

In order to study the molecular character of the polioviruses isolated from AFP cases in China,and provide a theoretic basis for maintaining a nopolio wild type virus status,we carried out intratypic differentiation(ITD)test to all the AFP isolates isolated by the provincial polio lab staff using PCR RFLP and ELISA methods.We found that comparing with Sabin vaccine,there were 24 isolates that had different enzyme cut maps by PCR RFLP method,1 of type Ⅰ,21 of type Ⅱ,and 2 of type Ⅲ;and there were another 22 isolates that had different antigen antibody reactions by ELISA method,7 of type Ⅰ,4 of type Ⅱ,and 11 of type Ⅲ,among these 22 isolates,3 were non Sabin like viruses(NSL),and the others were double reaction viruses(DRV).Further, we made genomic sequencing of VP1 region for all of 46 isolates.The results showed all the viruses isolated were OPV like polioviruses or vaccine derived polioviruses,no wild type poliovirus was found in 2002, China remains in a nopolio wild type virus status. Like wild type poliovirus,the oral polio vaccine virus is genetically unstable when replicating in the intestinal tract of human.The genomic variation of the polio vaccine virus results in virulence change and finally may lead to VAPP cases.In some local areas,circulation of polio vaccine viruses and existence of VDPVs were found.For the purpose of eliminating polio vaccine induced AFP cases,the intervention of inactivated polis vaccine(IPV) is needed.