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目的 对辽宁省2015年首次分离到的疫苗衍生脊髓灰质炎 (脊灰) 病毒 (VDPV) 进行病原学分析.方法 采集所涉1例急性弛缓性麻痹 (AFP) 患者血清标本进行脊灰中和抗体检测;采集患者粪便标本, 用L20B和RD细胞进行脊灰病毒分离;对脊灰病毒阳性分离物进行型内鉴定;对病毒VP1区进行基因测序和进化树分析.结果 该例AFP患者血清脊灰Ⅰ、Ⅱ、Ⅲ型中和抗体滴度分别为1:4、1:4、1:8;患者的9份粪便标本中, 2份标本的脊灰病毒分离阳性;阳性分离物的型内鉴定为PVⅡ-SL-Discordant;与Ⅱ型脊灰疫苗株 (Sabin株) 相比, 两毒株VP1区序列核酸变异数分别为21个 (2.3％) 和22个 (2.4％), 鉴定为Ⅱ型VDPV.结论 该AFP病例未持续排毒, 其Ⅱ型VDPV分离株未引起循环.灭活脊灰病毒疫苗纳入免疫规划后, 需加强脊灰病原学监测.“,”Objective To determine the etiology of the f irst vaccine-derived poliovirus (VDPV) strain in Liaoning province in 2015. Methods We collected serum samples f rom an acute f laccid paralysis (AFP) case to test f or neutralizing antibodies against poliovirus, and stool specimens to isolate poliovirus by L20 B and RD cell cultures;we conducted intratypic dif f erentiation (ITD) of poliovirus isolates and sequence analysis of the VP1 coding regions. Results Neutralizing antibody titers of the AFP case for poliovirus type Ⅰ, Ⅱ, and Ⅲ were 1:4, 1:4, and 1:8, respectively. Polioviruses were isolated f rom two of nine stool specimens f rom the case and were identified as PV Ⅱ-SL-Discordant by ITD. Compared with the Sabin Ⅱ strain, 21 (2.3％) and 22 (2.4％) nucleotides were different in the VP1 regions of the two isolates, which were identified as type Ⅱ VDPVs. Conclusions The AFP case did not excreted poliovirus continuously, and the individual's type II VDPV did not circulate. We should strengthen polio etiological monitoring af ter introducing inactivated poliovirus vaccine into the National Immunization Program.