Pickering J M, Thomas H C, Karayiannis P
Department of Medicine, Imperial College School of Medicine at St Mary's, London, UK.
J Gen Virol. 1997 Jan;78 ( Pt 1):53-60. doi: 10.1099/0022-1317-78-1-53.
Significant variation was found, between 46 isolates of hepatitis G virus (HGV), following direct sequencing of subgenomic PCR fragments from either or both the NS-3 and putative 'core' peptide. Nucleotide sequences of most HGV NS-3 fragments varied by 10-30% and of most putative 'core' peptide fragments by 2-20%. HGV was therefore shown to be much less variable than hepatitis C virus (HCV) and pairwise comparisons of HGV sequences demonstrated a single distinct distribution of evolutionary distances. Construction of phylogenetic trees, bootstrap analysis and calculation of mean distances between possible subtypes also indicated one level of variation between HGV NS-3 and putative 'core' peptide sequences, and the suggested degree of variation between isolates was similar to that between HCV subtypes. No evidence for clustering of sequences into multiple subtypes or genotypes was found. Although very small subgenomic fragments of HCV are indicative of the viral genotype it seems that the assignment of genetic groups is not possible for HGV using such small subgenomic fragments. The relatively limited genetic variation observed in HGV may reflect a relatively low level of host selection pressure stemming from the low level of host immunity stimulated by this virus.
对来自NS-3和假定“核心”肽段中一个或两个的亚基因组PCR片段进行直接测序后，发现46株庚型肝炎病毒（HGV）之间存在显著差异。大多数HGV NS-3片段的核苷酸序列差异为10%-30%，大多数假定“核心”肽段片段的差异为2%-20%。因此，研究表明HGV的变异性远低于丙型肝炎病毒（HCV），对HGV序列的成对比较显示出进化距离的单一独特分布。系统发育树的构建、自展分析以及可能亚型之间平均距离的计算也表明HGV NS-3和假定“核心”肽段序列之间存在一个变异水平，并且分离株之间的变异程度与HCV亚型之间的相似。未发现序列聚集成多个亚型或基因型的证据。尽管HCV的非常小的亚基因组片段可指示病毒基因型，但对于HGV而言，使用如此小的亚基因组片段似乎无法进行基因分组。在HGV中观察到的相对有限的遗传变异可能反映出由于该病毒刺激的宿主免疫水平较低而导致的相对较低水平的宿主选择压力。
