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目的 通过对乙型肝炎病毒 (HBV)前S2基因序列的研究 ,证实HBV在慢性感染者中以准种状态存在 ,并对前S2序列异质性进行初步的阐明。方法 以中国株HBV基因序列为依据 ,设计特异性PCR引物 ,自 5 1例慢性HBV感染患者血清中扩增HBV前S2基因序列 ,采用聚丙烯酰胺凝胶电泳技术展示缺失突变 ,随机选择克隆测序 ,确定病毒的变异程度。结果 聚丙烯酰胺凝胶电泳结果发现 ,5 2 9% (2 7/ 5 1)患者血清中可获得 2或 3条扩增条带 ;测序结果发现前S2基因序列存在缺失突变高发区 ,氨基酸序列分析示缺失突变主要位于前S2编码蛋白的氨基端。结论 HBV前S2序列内有一缺失高变区 ,并在患者体内表现为多种变异形式 ;氨基端附近的变异可能影响中和抗体的识别作用。结果提示HBV慢性携带者体内有HBV准种共存。
Objective To study the sequence of pre-S2 gene of hepatitis B virus (HBV), and to confirm the existence of HBV in quasi-species of chronically infected individuals and preliminary elucidate the heterogeneity of pre-S2 sequence. Methods Based on the Chinese strain HBV gene sequence, specific PCR primers were designed. The HBV preS2 gene sequence was amplified from sera of 51 patients with chronic HBV infection. Polyacrylamide gel electrophoresis (PAGE) was used to display the deletion mutation. Randomly selected cloned and sequenced , Determine the degree of variation of the virus. Results The results of polyacrylamide gel electrophoresis showed that 2 or 3 bands could be obtained in 529% (27/51) of the patients. Sequencing results showed that there was a high incidence of deletion mutation in the pre-S2 gene sequence. The amino acid sequence Analysis revealed that the deletion mutation was mainly located at the amino terminus of the preS2-encoded protein. Conclusion There is a deletion hypervariable region in the pre-HBV sequence of HBV, and it shows many variations in the patient’s body. The variation near the amino terminal may affect the recognition of neutralizing antibodies. The results suggest that HBV quasi-coexistence of HBV carriers in vivo.