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丙型肝炎病毒(HCV)包膜E2蛋白氨基端的高变区1(HVR1)由27个氨基酸组成,是HCV蛋白中变异频率最高的肽段。HVR1含中和抗体表位,同时对HCV细胞侵入起重要作用,其结构与功能的关系目前尚不清楚。本研究对H77株包膜蛋白基因中的HVR1进行了一系列缺失突变,然后将突变体表达质粒与假病毒包装质粒共转染人胚肾(HEK)293T细胞,用蛋白免疫印迹法检测细胞中HCV包膜E2蛋白的表达,用荧光定量聚合酶链反应检测培养上清液中的HCV假病毒(HCVpp)含量,以人肝癌细胞Huh7.5为靶细胞检测HCVpp的感染力。结果显示,缺失整个HVR1或HVR1中部分氨基酸残基对HCV包膜蛋白表达及HCVpp产量均无明显影响,但对HCVpp感染力产生不同影响。缺失第16～24位氨基酸残基导致HCVpp感染力增强,缺失第1～8位或1～12位氨基酸残基仅部分降低HCVpp感染力,缺失第13～15位和25～27位中的任意一个氨基酸残基均导致HCVpp感染力低于原型的5%。结果提示,HVR1中第13～15位和25～27位的6个氨基酸是介导HCV感染的关键氨基酸残基。
The amino-terminal hypervariable region 1 (HVR1) of the Hepatitis C virus (HCV) envelope E2 protein consists of 27 amino acids and is the most frequently mutated peptide in HCV proteins. HVR1 contains neutralizing antibody epitopes and plays an important role in the invasion of HCV cells. The relationship between its structure and function is not yet clear. In this study, a series of deletion mutations of HVR1 in the envelope protein of H77 strain were carried out. The mutant plasmids were co-transfected with 293T cells of human embryonic kidney (HEK) 293T cells with pseudovirion packaging plasmids and detected by Western blotting The expression of HCV envelope E2 protein was detected by fluorescence quantitative polymerase chain reaction (HCVpp) in the culture supernatant, and the infectivity of HCVpp was detected by human hepatocellular carcinoma Huh7.5 cells. The results showed that deletion of some amino acid residues in HVR1 or HVR1 had no significant effect on HCV envelope protein expression and HCVpp production, but had different effects on HCVpp infectivity. The deletion of amino acid residues 16-24 resulted in an enhanced HCVpp infectivity, the deletion of amino acid residues 1 to 8 or 1 to 12 only partially reduced HCVpp infectivity, and lacked any of positions 13-15 and 25-27 One amino acid residue each resulted in a HCVpp infectivity of less than 5% of the prototype. The results suggest that HVR1 amino acids 13 to 15 and 25 to 27 are the key amino acid residues that mediate HCV infection.