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目的通过对隐匿性乙肝感染者S区基因变异位点的分析及相关蛋白空间结构的预测,探讨无偿献血者隐匿性乙肝感染的分子生物学机制。方法对80例HBs Ag-/HBV DNA+无偿献血者进行血清学补充试验,并对追踪确认的隐匿性乙肝感染者,应用巢氏PCR技术对S区基因进行扩增和序列测定,并将测得基因片段与NCBI Gen Bank数据库做序列比对分析,明确突变位点,同时进行蛋白模型构建,进行空间结构的分析。结果 HBs Ag-/HBV DNA+无偿献血者血清学检测模式多样,以抗-HBc阳性为主,追踪试验确认4例隐匿性乙肝感染者,有3例巢氏PCR扩增出S区基因序列,2例发生突变,蛋白预测提示氨基酸改变可能影响抗原决定簇空间构象,造成抗体结合位点改变或识别能力减弱。结论隐匿性乙肝感染者S区容易发生变异,尤其是a抗原决定簇氨基酸的改变导致蛋白质空间构象的变化,可能是造成隐匿性乙肝发生的原因之一。
Objective To investigate the molecular biological mechanism of occult hepatitis B infection in unpaid blood donors by analyzing the S gene mutation sites in the occult hepatitis B virus and predicting the spatial structure of related proteins. Methods 80 cases of HBs Ag- / HBV DNA + blood donors were serologically supplemented, and follow-up confirmation of occult hepatitis B infection, the use of nested PCR amplification of S gene and sequencing, and measured Gene fragments and NCBI Gen Bank database for sequence alignment analysis, a clear mutation sites, at the same time, protein model construction, spatial structure analysis. Results Serological detection patterns of HBs Ag- / HBV DNA + non-reimbursed blood donors varied with anti-HBc positive and follow-up test confirmed 4 cases of occult hepatitis B virus infection. There were 3 cases of S district gene sequence amplified by nest PCR and 2 Cases of mutations, protein prediction tips amino acid changes may affect the spatial conformation of antigenic determinants, resulting in changes in antibody binding sites or decreased recognition ability. Conclusions Mutation in S region of occult hepatitis B is prone to occur. In particular, the alteration of the amino acid of a epitope leads to the change of spatial conformation of protein, which may be one of the causes of occult hepatitis B.