4例乙肝表面抗原阴性乙肝病毒DNA阳性标本结果分析

目的 探讨4例乙肝病毒HBV-DNA阳性标本乙肝表面抗原(HbsAg)阴性的原因.方法 4例HbsAg阴性HBV-DNA阳性标本和1例HbsAg阳性HBV-DNA阳性标本,碱裂解法提取乙肝病毒基因组,采用巢式PCR扩增s基因全长片段,T-A克隆后测序,根据s基因序列推导氨基酸序列,分析乙肝表面抗原α决定簇区域的氨基酸变异情况.结果 与参考株比较,5例血清中HBV-DNAs基因均出现不同位点碱基突变,导致乙肝表面抗原α决定簇区域的氨基酸突变主要为:1号标本R122K、I126A、S143T;2号标本R122K、I126N、Q129N;3号标本R122K、I126S、T131N、M133T;4号标本R122K、I126S、T131N、M133T及5号标本的R122K.结论 乙肝表面抗原α决定簇区域126位氨基酸突变可能会影响HbsAg的检测结果.

Analysis of the result of 4 samples with HbsAg negative and HBV-DNA positive

Objective To investigate the reason of 4 samples with positive HBV-DNA but negative HbsAg. Method Hepatitis B virus genome was extraeted by alkaline lysis method from 4 eases with 1 case as the control, the HbsAg and HBV-DNA of which were both positive. The segment of entire ＂s＂ gene was amplified by nested PCR, and then the segment was sequeneed after T-A cloning. The amino acids sequence were deduced via the ＂s＂ gene and the mutations of ＂ α＂ decision was analysed. Result Compared with the reference strain, there were different sites of ＂s＂ gene mutation in 5 samples. The amino acid mutations sites of ＂α＂ determine in hepatitis B surface antigen were： No. 1 R122K, I126A, S143T; No. 2 R122K, I126N, Q129N; No. 3 R122K, I126S, T131N, M133T; No. 4 R122K, I126S, T131N, M133T and No. 5 of R122K. Conclusion The 126 point amino acid mutation of Hepatitis B surface antigen may affect the HhsAg test results.