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中国脊髓灰质炎（脊灰）病毒疫苗株普遍存在基因变异的现象，如重组、点突变等〔１〕。我们选出１０株有代表性的变异株，在具有人脊灰病毒受体基因的转基因小鼠ＰＶＲ－Ｔｇ２１〔２〕中做毒力分析，发现Ｓａｂｉｎ１基因型（ＶＰ１）与野毒基因型（３Ｄ）的重组株显示很强的神经毒力，其ＰＤ５０ｉｎＴＣＩＤ５０（简称ＰＤ５０）值为４．５，而Ｓａｂｉｎ１标准株的ＰＤ５０值大于８．０。另外两株Ⅰ型疫苗株只在关键性核苷酸位点发生突变，只在位点５２５－Ｕ发生突变的一株，其ＰＤ５０值为５．０，另一株在位点４８０－Ｇ及２７９５－Ａ突变，其ＰＤ５０值为５．８，均显示较强的神经毒力。一株Ｓａｂｉｎ２基因型（ＶＰ１）与Ｓａｂｉｎ３基因型（３Ｄ）的重组株，其神经毒力（ＰＤ５０≥５．９）亦明显高于Ｓａｂｉｎ２标准株（ＰＤ５０＞７．５）；而１株Ｓａｂｉｎ２基因型（ＶＰ１）与（Ｓａｂｉｎ１＋Ｓａｂｉｎ２）基因型（３Ｄ）重组株的神经毒力（ＰＤ５０＝７．５０）无明显提高。对Ⅲ型疫苗株的神经毒力分析发现，１株Ｓａｂｉｎ３基因型（ＶＰ１）与Ｎｏｎ－Ｓａｂｉｎ基因型（３Ｄ）重组株的神经毒力，高于仅在核苷酸位点４７２－Ｕ突变的一株疫苗株。值得提出的是，另一株Ⅲ型疫苗?
China polio (polio) virus vaccine strains widespread phenomenon of gene mutation, such as recombination, point mutations [1]. We selected 10 representative mutants and did virulence analysis in PVR-Tg21 (2) transgenic mice harboring human poliovirus receptor gene. It was found that Sabin1 genotype (VP1) and wild type genotype ) Showed highly potent neurotoxicity with a PD50inTCID50 (referred to as PD50) value of 4.5 and a Sabin1 standard strain with a PD50 value of greater than 8.0. In addition, the two strains of type I vaccine only mutated at the key nucleotide sites. Only one locus 525-U mutation had a PD50 value of 5.0 and the other was at site 480-G and 2795-A mutation, the PD50 value of 5.8, all showed strong neurotoxicity. A recombinant strain of Sabin2 genotype (VP1) and Sabin3 genotype (3D) also showed significantly higher neurotoxicity (PD50≥5.9) than Sabin2 standard (PD50> 7.5). One Sabin2 gene (VP1) and (Sabin1 + Sabin2) genotype (3D) recombinant strains of neurotoxicity (PD50 = 7.50) no significant increase. The neurovirulence analysis of the type III vaccine strain revealed that the virulence of one Sabin3 genotype (VP1) and the Non-Sabin genotype (3D) recombinant strain was higher than that of the 472-U mutant only at the nucleotide position A vaccine strain. It is worth mentioning that another type III vaccine?