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目的研究中国丙型肝炎患者III/2a型丙型肝炎病毒(HCV)包膜蛋白E2/NS1高变区1(HVR1)序列变异的规律及意义。方法应用逆转录巢式PCR技术,从38例III/2a型HCV感染患者血清中 ,扩增HCV部分包膜区基因片断(nt1460～1582,HCV J6),纯化后直接采用双脱氧链末端终止法进行序列分析。结果本组III/2a型HCVHVR1位于氨基酸(aa)384～408位,与有关文献报道的结果(383～410或414位)略有差异。与HCV J ,河北株、HCV 1和HCV J6相应序列比较 ,核苷酸(nt)的同源性依次为 :32 %～56 %(平均45.4 %) ,41.7 %～60.0 %(50.7 %) ,41.3 %～62.7 %(53.3 %)和49.3 %～73.3 %(58.9 %) ;aa的同源性依次为 :16 %～48 %(33.5 %) ,28 %～60 %(42.5 %) ,24 %～64 %(45.3 %)和20 %～64 %(39.4 %)。我们在本组HVR1内发现 ,5个较保守的aa位点:385位为Thr,389 ,390和406位为Gly,403位为Phe,其中390位未见于其它报道。结论本组序列变异集中于aa384～408位 ,且以异义替换为主 ,构成了免疫逃逸的基础 ,但某些位点上序列相对保守,这些位点可能是HCV抗原表位的结构位点。对HVR1序列变异规律及其生物学意义的进一步研究 ,将有助于了解HCV的致病机制及疫苗的研制。
Objective To study the regularity and significance of the variation of the sequence of HVR1 in type III / 2a hepatitis C virus (HCV) envelope protein (HCV) in patients with hepatitis C in China. Methods Reverse transcriptase nested polymerase chain reaction (PCR) was used to amplify HCV partial envelope region (nt1460 ~ 1582, HCV J6) from the serum of 38 patients with type III / 2a HCV infection and purified directly by dideoxy chain termination Sequence analysis. Results HCVHVR1 of group III / 2a was located at amino acid (aa) 384 ~ 408, which was slightly different from the reported results (383-410 or 414). Nucleotide (nt) homology was 32% ~ 56% (average 45.4%), 41.7% ~ 60.0% (50.7%) compared with the corresponding sequences of HCV J, Hebei strain, HCV 1 and HCV J6, 41.3% -62.7% (53.3%) and 49.3% -73.3% (58.9%), respectively. The homology of aa was 16% -48% (33.5%), 28% -60% ~ 64% (45.3%) and 20% ~ 64% (39.4%). We found in this group of HVR1, five more conserved aa sites: 385 for the Thr, 389, 390 and 406 for the Gly, 403 for Phe, of which 390 were not found in other reports. Conclusion The sequence variations in this group are concentrated in aa384 ~ 408, and are mainly based on the substitution of the substitutions, which form the basis of immune escape. However, the sequences in these sites are relatively conservative. These sites may be the structural sites of HCV epitopes . The further study on the variation of HVR1 sequence and its biological significance will help to understand the pathogenesis of HCV and the development of vaccines.