作者用聚合酶链反应 ( PCR)法检测乙型肝炎病毒 ( HBV) DNA,评价了高危婴儿在HBV免疫接种后的长期保护效果 ,还对接种后 HBV- DNA持续阳性儿童检测了 S基因的 DNA序列。　　作者对 1981年至 1993年之间出生的母亲为 HBs Ag和 HBe Ag阳性的 2 5 1名高危婴儿进行了随访观察。这些 The authors used polymerase chain reaction (PCR) to detect Hepatitis B virus (HBV) DNA to evaluate the long-term protection of high-risk infants after HBV immunization. S-DNA was also detected in children with persistent HBV-DNA after vaccination sequence. The authors followed up a total of 251 high-risk infants who were born between 1981 and 1993 and whose mothers were HBs Ag and HBeAg-positive. These ones