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目的研究中国(未包括香港、澳门特别行政区和台湾地区,下同)2009年从急性弛缓性麻痹(Acute FlaccidParalysis,AFP)病例监测系统中,分离到的Ⅰ型脊髓灰质炎(脊灰)病毒(Poliovirus,PV)分子生物学特征,为维持无脊灰状态提供依据。方法采用逆转录-聚合酶链反应(Reverse Transcription-Polymerase Chain Reaction,RT-PCR),对I型PV的VP1编码区进行扩增,并对PCR产物进行核苷酸序列测定和分析;对VP1编码区的核苷酸突变热点和神经毒力位点进行分析,并建立亲缘关系进化树分析毒株间的进化关系。结果中国2009年从AFP病例监测系统中共分离到57株I型PV。对这57株PV进行VP1编码区核苷酸序列测定和分析,未发现PV野毒株或疫苗衍生PV。但发现5株高变异株,其中分离于两例AFP病例的两株高变异株的核苷酸序列同源性100%。同时序列比对结果表明,在VP1编码区的两个核苷酸(nt2747和nt2749)是两个突变热点。结论根据江西省和湖北省两株高变异株的流行病学及实验室检测结果,不能排除它们之间发生了短时间的循环,有待于深入研究。同时,突变热点的存在提示毒株受到选择压力的影响,容易回复突变成野生型,从而带来一系列的神经毒力等表型方面的变化。
Objective To study the genetic polymorphisms of poliovirus type 1 (poliovirus) isolated from China (excluding Hong Kong, Macao Special Administrative Region and Taiwan region, the same below) from 2009 surveillance system of Acute Flaccidaralysis (AFP) Poliovirus, PV) molecular biology features, to provide a basis for maintaining poliovirus status. Methods VP1 coding region of type I PV was amplified by Reverse Transcription-Polymerase Chain Reaction (RT-PCR). The PCR products were sequenced and analyzed. Region nucleotide mutation hot spots and neurovirulence sites were analyzed and phylogenetic tree was established to analyze the evolutionary relationship between strains. Results In 2009, 57 type I PVs were isolated from the AFP case surveillance system in China. The 57 PVs were sequenced and analyzed for the nucleotide sequence of the VP1 coding region. No PV field virus or vaccine-derived PV was found. However, five highly mutated strains were found, of which two highly variant strains isolated in two AFP cases had a nucleotide sequence homology of 100%. At the same time, sequence alignment showed that two nucleotides (nt2747 and nt2749) in the VP1 coding region were two hot mutations. Conclusion According to the epidemiology and laboratory test results of two highly mutated strains in Jiangxi Province and Hubei Province, we can not rule out the short cycle between them. It remains to be further studied. At the same time, the existence of mutation hot spots suggests that the strain is susceptible to selection pressure and easily returns to wild type, resulting in a series of phenotypic changes such as neurovirulence.