脊髓灰质炎病毒VP1区的基因变化及疫苗衍生脊髓灰质炎病毒的流行情况

摘要

脊髓灰质炎(脊灰)病毒有3个血清型.VP1是脊灰病毒衣壳蛋白之一,它有4个抗原决定簇,可以诱导中和抗体,具有血清型特异性.脊灰病毒由于其RNA依赖性RNA聚合酶缺乏严密的自我校正功能,在自身复制过程中精确性下降,因此,会产生很多点突变,出现一些VP1区核苷酸突变热点.口服脊灰减毒活疫苗(OPV)的应用,有效地控制了脊灰,但因OPV病毒在人体肠道内复制过程中发生碱基突变,导致其神经毒力回升,引起疫苗相关麻痹型脊灰和出现疫苗衍生脊灰病毒(VDPV),使全球多次发生循环VDPV事件,对消灭脊灰带来新的挑战.为此,有关学者建议停止使用OPV,改用脊灰灭活疫苗或两种疫苗相结合的序贯免疫程序.%Polioviruses are classified into three serotypes.VP1 is one of the capsid proteins and has four epitopes which can stimulate neutralizing antibody to polioviruses.This capsid protein also determines the specificity of serotypes.Because the viral RNA polymerases generally lack self-proofreading mechanisms,polioviruses become one of the most rapidly evolving viruses and have several rapid variation sites in VP1 gene.With the routine immunization with oral poliovirus vaccine(OPV), the incidence of poliomyelitis has decreased dramatically.However, genetic variation may occur when the OPV viruses replicate in host's intestinal mucosa,resulting in reversion to neurovirulence of the polioviruses and leading to vaccine-associated paralytic poliomyelitis and vaccine-derived poliovirus (VDPV).There have been several events of the circulating VDPV worldwide, which makes new challenge to polio eradication.Therefore, experts suggest an immunization programme of inactivated poliovirus vaccine (IPV) in stead of OPV, or adoption of sequential immunization with IPV and OPV.