前C区A83点突变在乙型肝炎病毒感染中的分布

乙型肝炎病毒（ＨＢＶ）前Ｃ区Ａ８３点突变相当常见。我们设计一种错配引物，通过聚合酶链反应（ＰＣＲ）在含Ａ８３的序列中引进Ｂｓｕ３６１限制酶位点，经酶切即可检出Ａ８３。用以分析急慢性ＨＢＶ感染７７例：在乙型肝炎ｅ抗体（抗－ＨＢｅ）（＋）４８例中检出Ａ８３优势感染６５％；乙型肝炎ｅ抗原（ＨＢｅＡｇ）（＋）２９例中检出Ａ８３非优势混合感染３８％。急性乙肝和慢性无症状ＨＢＶ携带者中均未见Ａ８３。提示变异须

Distribution of pre-core A83 point mutation inhepatitis B virus infections

e designed a mispairing primer, which could in-troduce a Bsu36I restriction site into the amplifiedfragment of A83 mutant. Following PCR, the 102bpwas diagnosed by the restriction endonuclease, andthe variation was detected by demonstration of 82bpand 20bp bands on gel electrophoresis (RFLP). Withthe method, 77 cases of acute and chronic HBV infec-tions were analysed. Among those, 31 (65%) mutantswere detected in 48 anti-HBe-positive cases. and in29 HBeAg-positive cases, 11 (38%) were co-infectedwith mutated and wild isolates. No pre C defect wasfound in acute hepatitis B and chronic asymptomaticcarriers, suggesting that mutation occurs only afterimmune selection. The HBeAg defective variant appears to be involved in the loss of virus tolerance,and therefore in the pathogenesis of acuteexacerbation of chronic carriage as demonstrated inthis study. The various chronic liver diseases had anapproximate mutation frequency, and it seems thatA83 mutation nearly makes HBV infection persist.