乙型肝炎病毒前C区基因变异的研究

作者应用聚合酶链反应（ＰＣＲ）检测ｅ系统阳性的慢件乙型肝炎（乙肝）患者血清乙肝病毒（ＨＢＶ）ＤＮＡ，筛选出乙肝ｅ抗原（ＨＢｅＡｇ）阳性／乙肝ｅ抗体（抗—ＨＢｅ）阴性和ＨＢｅＡｇ阴性／抗—ＨＢｅ阳性各２０份ＰＣＲ阳性血清，分别用人工合成的ＨＢＶ前Ｃ区基因寡核苷酸探针Ｍ０（无突变），Ｍ１（１点突变），Ｍ２（２点突变）进行斑点杂交，结果发现ＨＢｅＡｇ阴性／抗—ＨＢｅ附性慢性乙肝患含有１７例（占８５％）在１８９６位核苷酸发生点突变，形成终止密码，其中１０例（占５０％）发生２点突变。选突变ＰＣＲ产物直接测序，同样证实点突变的存在。提示乙肝患含ＨＢｅＡｇ阳性自然转换为抗—ＨＢｅ阳性、并不一定是病毒复制减弱，而可能足ＨＢＶＤＮＡ前Ｃ区发生了基因变异。

Gene variation in the pre-C region of hepatitis B virus

e examined the serum HBV DNA of the chron-ic hepatitis B patiens with positive c-system by usingpolymerase chain reaction (PCR). Twenty samples ofHBeAg( ) / anti-HBe(-) postitive PCR products and20 samples of HBeAg(-) / anti-HBe( ) positive PCRproducts were selected. These produets weredot-hybridized by synthetic HBV pre-C region gencoligonucleotide probes MO (non mutated), M1 (one)point-mutated), M2 (two point-mutatied). The re-sults thus obtained showed that for 85% (17 / 20) ofthe chronic hepatitis patients with HBeAg(-)/ anti-HBe( ), point mutation occurred at the 1 896thnucleolide, resulting in the stop codon, and half( 10 / 20) of the patients suffered two points mutation.The direct determination of the sequence of some mu-tation PCR products selected proved the existence ofpoint mutation. The result indicated that the naturalconversion of hepatitis patients' HBeAg( ) toanti-HBe( ) may have resulted from thegenovariation in the pre-c region of HBVDNA ratherthan from the decreased of virus replication.