SARS冠状病毒M基因变异规律分析
Analysis on M genes variation rules of SARS-CoV
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摘要:目的 测定SARS冠状病毒(SARS-CoV)GD322株M基因序列, 与其他SARS-CoV M基因进行比较分析, 初步了解SARS-CoV在流行过程中M基因的变异规律。方法 提取GD322株RNA, 经RT-PCR扩增M基因后克隆至T-载体, 转化DH5α, 并进行序列测定。以SARS冠状病毒多伦多株2(TOR2)M基因为基准, 利用Clustal X软件与其他SARS-CoV M基因进行比较, 了解变异情况, 采用Protean软件预测α螺旋和B细胞抗原表位。结果 完成GD322株基因测序(AY702026), 通过对已发表81株SARS-CoV M基因序列初步分析, 选定TOR2为基准株。发现36株M基因与TOR2株序列相同, 5株存在同义突变, 40株存在非同义突变。共有11个突变位点, 其中9个非同义突变位点, 2个同义突变位点。对非同义突变代表株Frankfurt1和TW5的M基因进行α螺旋和B细胞抗原表位预测, 结果和基准株序列比, 差异无统计学意义。结论 SARS-CoV M基因虽然有随流行时间推移突变逐渐增大的趋势, 但总突变率低, 基因序列较稳定, 且香港M旅馆相关毒株变异小于香港M旅馆无关毒株。变异对其抗原性无影响。Abstract:Objective To discover the variations rules of M genes through sequencing the M gene of SARS-CoV GD322 isolate and to compare it with those of published on GenBank.Methods RNA was extracted from SARS-CoV GD322 strain and used for RTPCR, then the PCR prducts were cloned into pGEMT vector and transformed DH5, with which was followed M gene sequencing.This M gene sequence and other 81 M genes published on GenBank were used to compare with the M gene of TOR2 with Clustal X, from which the variation rules of M genes were gotten.Then, predicted the turn and the possible Bcell epitopes with Protean program and analyzed the variations effect on them.Results After sequencing the gene of GD322 isolate(A Y702026)and analyzing those published 81 M genes, TOR2 was selected as the reference strain.Among the 82 M genes, 36 isolates M genes were same as that of TOR2, 5 isolates syno nymous mutation and 40 isolates nonsynony mous mutation.11 nucleotide mutation sites were discovered in the 82 M genes, 9 of which were nonsy nonymous mutation and 2 synonymous mutation.The results of predicting the turn and the B cell epitopes of M genes of Frankfurt 1 and TW5 showed no differences to those of TOR2.Conclusion Though the variations of SARS CoV M genes are of gradually in creasing trend during the course of epidemic spread, the total mutation rate is quite small and the M gene sequences are considerably stable, the isolates related to M hotel varied less than those with no relation to.The variations of M genes have hardly affected the antigenicity of M protein.
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