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目的研究西藏自治区1999~2002年≤5岁儿童埃柯病毒7型(ECHO7)VP1区编码基因特征及其分子流行病学特点。方法选取1999~2002年从西藏自治区<15岁急性弛缓性麻庳(AFP)病例和≤5岁到儿童医院就诊儿童及部分健康儿童的659份粪便标本中分离的16株ECHO7病毒,进行核糖核酸(RNA)提取,VP1编码区逆转录-聚合酶链反应(RT-PCR),PCR产物的核苷酸序列测定和分析。结果1999年的标本分离到9株,2000年分离到7株,VP1区核苷酸序列测定结果证实,此16株经血清中和试验定型的病毒全部为ECHO7病毒。其它年份未分离到ECHO7病毒。16株ECHO7病毒VP1区基因全长都是876bp,翻译的氨基酸全长292aa。所测16株ECHO7病毒序列之间同源性为86.73~100.00%。所测序列和ECHO7原型株——Wallace株相比,同源性为77.85%~78.99%;和引起致死性脑脊髓炎的ECHO7变异株——UMMC株相比,同源性为81.67%~83.79%。所构建的ECHO7病毒遗传进化树将已知的ECHO7病毒划分为4个基因型,西藏自治区分离的ECHO7病毒独自形成1个基因型(D基因型)。结论首次报告的西藏自治区1999、2000年儿童中流行的ECHO7病毒为一个新的基因型(D基因型)。16株D基因型病毒划分为2个基因亚型D1、D2。1999年流行的为D1;2000年流行的为D2。西藏自治区1999、2000年ECHO7流行为不同的病毒亚型引起。2001~2002年未发现ECHO7的持续流行。
Objective To study the molecular characteristics and molecular epidemiology of VP1 gene of ECHO7 in children aged ≤ 5 years in Tibet Autonomous Region from 1999 to 2002. Methods Sixteen ECHO7 viruses isolated from 659 stool specimens of children with acute flaccid Atrachis (AFP) <15 years old and children <5 years old to children’s hospital in Tibet Autonomous Region from 1999 to 2002 and selected from some healthy children were selected for RNA analysis (RNA) extraction, VP1 coding region reverse transcription-polymerase chain reaction (RT-PCR), PCR products of nucleotide sequence determination and analysis. Results Nine isolates were isolated in 1999 and seven isolates were isolated in 2000. The results of nucleotide sequence analysis of VP1 showed that the 16 strains were all ECHO7 by the serum neutralization test. Other years did not isolate the ECHO7 virus. The total length of VP1 gene of 16 ECHO7 viruses was 876bp, and the translated amino acid was 292aa in length. The homology between 16 strains of ECHO7 was 86.73 ~ 100.00%. Compared with the ECHO7 prototype strain - Wallace strain, the homology was 77.85% -78.99%, and the homology was 81.67% -83.79 with the ECHO7 mutant strain -UMMC strain causing lethal encephalomyelitis %. The constructed ECHO7 virus phylogenetic tree divides the known ECHO7 viruses into four genotypes, and the ECHO7 virus isolated in the Tibet Autonomous Region alone forms one genotype (D genotype). Conclusion The first report of the ECHO7 virus among children in 1999 and 2000 in the Tibet Autonomous Region was a new genotype (D genotype). Sixteen D genotypes were divided into two subtypes D 1, D 1 and D 1 in 1999, and D 1 in 2000; Tibet Autonomous Region 1999, 2000 ECHO7 epidemic caused by different virus subtypes. 2001-2002 did not find the continued popularity of ECHO7.