丙型肝炎病毒6a型感染的状态与分析

目的:初步探讨丙型肝炎病毒6a型感染的状态.方法:对经HCV 5'非编码区(5'NCR)复合酶切分型结果为6a的3例样本(95,126,150)进行5'NCR和NS5B区的扩增、测序,然后将5'NCR和NS5B区序列与24个HCV全基因参考序列(均来自GenBank)比对并构建遗传进化树.结果:对3例分型结果为6a型的样品进行5'NCR序列分析发现,这3例样品都具有6a型特征性的第-145位的CA碱基插入,且与6a型参考序列Y12083的同源性最高,分别为0.993,0.987,0.993;进化树分析表明,3例样本都属于6a型.然而NS5B区的序列分析结果表明,95,126,150在NS5B区与1b型参考序列HC-J4的同源性最高,分别为0.934,0.930,0.926;进化树分析结果也显示它们都属于1b型,两个区的分型结果完全不同.为排除引物扩增效率的问题,使用6a型特异的引物对3例样品进行NS5B区扩增,3例样本扩增结果均为阴性.结论:我们发现的HCV 6a型的感染中,存在3例样品5'NCR和NS5B区的分型结果不一致,尚无直接证据证明其是否发生了基因重组.但是,我们的结果提示,在两个或两个以上区域进行HCV分型是非常重要的,且HCV基因型之间的重组必须纳入到HCV分型的考虑中来.

Analysis and state of HCV genotype 6a infection

OBJECTIVE: To investigate the infection state of hepatitis C virus genotype 6a in China. METHODS: Three (95, 126, 150)HCV genotype 6a serum samples were identified by digesting 5'NCR with compound enzyme method. Then, HCV 5'NCR and NS5B fragments were amplified from these samples by RT-PCR assay and sequenced. The phylogenetic trees of the samples were analyzed and compared with 24 HCV complete gene sequences from GenBank. RESULTS: The sequencing reports on 5'NCR showed "CA" bases in 3 serum samples (95,126,150) were inserted into -145 site, and the sequences of 3 serum samples had the highest homology with sequence Y12083( 0.934, 0.930, and 0.926, respectively). The results of the phylogenetic trees suggested these 3 serum samples belonged to HCV genotype 6a. The sequencing reports on NS5B showed the 3 serum samples also had the highest homology with HC-J4(0.934, 0.930, and 0.926, respectively), and the results of the phylogenetic trees suggested these 3 serum samples belonged to HCV genotype 1b. To exclude the influence of amplification efficiency of primers, NS5B fragments were amplified by HCV genotype 6a specific primers and no amplification products appeared. CONCLUSION: There are different results of HCV genotype by analyzing 5'NCR and NS5B in 3 samples infected with HCV genotype 6a. It may be related with gene recombination. It suggests HCV genotype should be analyzed on more than two regions.