丙型肝炎病毒非结构基因5b(NS5b)区一级结构的变异

Variation of primary structure in nonstructural region 5 b of hepatitis C virus

目的 分析中国丙型肝炎病毒非结构基因５ ｂ 区核苷酸序列变异。方法 以逆转录套式聚合酶链反应（ＲＴｎｅｓｔｅｄＰＣＲ） 从４９ 例中国病人的血清中获得互补的ＤＮＡ片段，产物克隆后测序。结果 ３３ 株系基因Ⅱ１ ｂ 型，１６ 株系Ⅲ２ ａ 型，中国ＨＣＶ株型与日本ＨＣＶ株型同属１ 个基因亚型，但在一些核苷酸保守位点上有一定的差异，对３３ 株Ⅱ１ ｂ 型和１６ 株Ⅲ２ ａ 型间的同源性进行比较，发现１６ 株Ⅲ２ ａ 型的同源性低于３３ 株Ⅱ１ ｂ 型的同源性。首次在ＨＣＶＮＳ５ ｂ 区发现１ 个新的３ 个核苷酸的缺失突变及１ 个移码突变。结论 同一基因亚型之内不同ＨＣＶ株的核苷酸序列可能具有一定的地理分布特征，每个地区有一定的流行株。

Objective To analyze the sequence variation in the nonstructural region 5 b(NS5 b) of hepatitis C virus (HCV) of China.Methods Complementary DNA fragments from sera of 49 Chinese patients were amplified by reverse transcription nested polymerase chain reaction (RT nested PCR) and the products were cloned and sequenced.Results 33 clones belonged to genotype 1 b and 16 clones were genotype 2 a. Several conserved nucleotide sites were found to be different from those of Japanese isolates though they belonged to an identical genotype. Comparison of average homology among the 33 clones of genotype 1 b and the 16 clones of genotype 2 a indicated that the average homology among genotype 2 a was lower than that among genotype 1 b. A deletion of three nucleotides and a frame shift, resulting from the introduction of an in frame stop codon, were firstly observed in the NS5 b region.Conclusion The nucleotide sequences of different HCV isolates of a same subtype may possibly possess the characteristics for different geographical distribution and so a definite epidemic HCV strain may emerge from a definite area.