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研究Ⅱ型脊髓灰质炎(脊灰)疫苗变异株的基因特征,为我国使用口服脊灰减毒活疫苗/脊灰灭活疫苗使用策略,维持无脊灰状态和全球最终消灭脊灰提供科学依据。根据型内鉴定的检测结果,从2000~2001年AFP病例分离到的Ⅱ型脊灰疫苗变异株中选取有聚集性的5株病毒进行全基因组序列测定(贵州省3株、山东省2株),并进行核苷酸、氨基酸同源性分析。贵州省3株病毒全基因组序列完全一致,但与SabinⅢ型病毒发生重组,重组区域在3A区(nt5343~5353);与疫苗株相比,Ⅱ型区域变异10个碱基,其中VP1区变异4个,与SabinⅡ型株核苷酸同源性为99·56%,氨基酸同源性99·34%;Ⅲ型区域变异9个碱基。山东省2株病毒全基因序列共享16个突变位点,没有发生重组,与SabinⅡ型株相比,VP1区分别变异7个和4个碱基,核苷酸同源性分别为99·22%和99·56%,氨基酸同源性分别为99·0%和99·67%。上述5株病毒在重要的减毒位点nt481、nt2909均发生突变。此研究中5株病毒分属于两个不同的传播链,但是共享nt481、nt2909、nt2992三个突变位点,这3个突变位点不在重组区域内,他们的共同作用可能是影响病毒传播力的重要因素,但目前尚无证据证明脊灰疫苗病毒型间重组会增加病毒的毒力及传播力。
To study the genetic characteristics of type Ⅱ poliomyelitis (polio) vaccine strains and provide a scientific basis for using the poliovirus / poliovirus inactivated polio vaccine in our country, maintaining poliomyelitis-free status and finally eradicating polio in the world . According to the results of intraspecific identification, five strains of poliovirus type Ⅱ poliovirus isolated from AFP cases from 2000 to 2001 were selected for genome-wide sequence analysis (3 in Guizhou Province and 2 in Shandong Province) , And nucleotide, amino acid homology analysis. The complete genome sequences of the three viruses in Guizhou province were identical, but they were recombined with the Sabin type III virus. The recombination region was in 3A region (nt5343 ~ 5353). Compared with the vaccine strain, the type Ⅱ region was 10 bp, of which VP1 region was 4 A, with Sabin Ⅱ nucleotide homology of 99.56%, amino acid homology of 99.34%; Ⅲ type region variation of 9 bases. There were 16 mutation sites shared by the two strains of viruses in Shandong province without recombination. Compared with the Sabin Ⅱ strain, the VP1 region was 7 and 4 bases in length, respectively. The nucleotide homology was 99.22% And 99.56% respectively. The amino acid homologies were 99.0% and 99.67% respectively. The above 5 viruses are mutated in important attenuating sites nt481 and nt2909. In this study, five viruses belonged to two different transmission chains, but shared three nt481, nt2909 and nt2992 mutation sites, which were not located in the recombination region. Their combined effect may affect the virus transmission Important factors, but there is no evidence that poliovirus type recombination will increase the virulence and transmission of the virus.