摘要
为探讨乙型肝炎表面抗原（ＨＢｓＡｇ）阴性乙型肝炎病毒（ＨＢＶ）感染这一特殊临床现象的分子生物学基础，对２例血清ＨＢｓＡｇ（－）／ＨＢＶＤＮＡ（＋）慢性肝炎患者ＨＢＶ的Ｓ基因全序列进行了分析，并与同时获得的１５例ＨＢｓＡｇ阳性患者序列和已发表的序列进行比较。结果发现一种新的ＨＢＶ插入变异株：１例在Ｓ基因第５１８位核苷酸前插入了６个核苷酸，从而在ＨＢｓＡｇ密码子１２２和１２３间“ａ”决定族前多编码两个氨基酸；另１例于５１８位核苷酸后插入９个核苷酸，导致在密码子１２３和１２４间增加３个氨基酸。在核苷酸水平插入部位恰好位于“ａ”编码区前的４个连续Ａ（核苷酸５１６－５１９）。我们推测Ｓ基因插入变异可能是病毒的一种免疫逃避机制。
In order to determine the molecular basis for the hepatitis B virus (HBV)infection with undetectable HBsAg, entire surface gene of HBV encoding major protein was amplified and se-quenced from 2 cases of HBsAg negative but HBV DNA positive patients with chronic liver disease.The results were compared with sequences from 15 HBsAg positive suects and also from consensus sequences previously published.Anew variant was described:one isolate with six base pair inser-tion introduced two additional aminoacids between codons 122 to 123 immediately upstream of the‘a’determinant of HBsAg;another isolate with nine base pair insertion gave rise to three aminoacids be-tween codons 123 to 124 immediately upstream of the‘a’determinant.HBV mutations are more commonly found in areas of the sequence characterized by runs of bases.In the cases under study,the insertion is associated with a run of four adenines before“a”determinant sequence (nucleotide 516 ～ 519 ).Our data provides a potential molecular explanation for the presence of HBV DNA in some cases of HBsAg negative patients.Our findings suggest that insertion variation might be an immune escape mutant of HBV.
出处
《中华传染病杂志》
CAS
CSCD
北大核心
1996年第3期129-133,共5页
Chinese Journal of Infectious Diseases
基金
国家和广东省自然科学基金
