摘要目的 探讨乙肝疫苗母-婴阻断失败者中乙肝病毒(HBV)全基因变异状况.方法 用PCR方法对启东地区11对乙肝疫苗免疫失败儿童-母亲配对血清及6例疫苗接种成功儿童的"大三阳"母亲血清扩增HBV全长基因,克隆测序后以Clustal X软件进行序列比对.病毒载量采用实时荧光定量PCR方法测定.结果 疫苗阻断失败和成功儿童的母亲HBV平均滴度分别为(1.2×107±3.1×1010)copies/ml和(1.6×107±8.8×1010)copies/ml,两组之间差异无统计学意义(P>0.05).在11例HBV DNA阳性的儿童中,4例(36.4%)有HBsAg"a"决定簇的氨基酸改变,表现为T125A、I126T、Q129H、M133V、D144V和G145A等6种不同突变形式,但母亲中HBsAg"a"决定簇均为野生型.疫苗接种失败的儿童中HBV preS1、preS2、S、X、preC/C和P基因的平均突变率分别为0.38%、0.22%、0.27%、0.17%、0.11%和0.11%.preS1区nt2999-3157、S区nt529-677、C区nt1955-2016和P区nt923-1001、nt2489-2602为病毒基因组中最易发生突变的区域.结论 经主动和被动免疫后,儿童体内HBV突变可发生于所有开放阅读框架内.除s基因外,preS和P基因的突变可能也与免疫逃逸有关.

abstractsObjective To determine the factors responsible for failed postnatal immunoprophylaxis for hepatitis B virus(HBV) in Qidong, China. Methods Eleven children who developed into chronic HBV infection after receiving HBIG and HBV recombinant vaccines were recruited into the study. Eleven paired mothers with chronic hepatitis and other 6 mothers whose children successfully generated anti-HBs after im-munoprophylaxis were included as the control in the study. Full-length HBV DNA was amplified through ser-um sample by PCR method and underwent cloning and sequencing. HBV DNA level was quantified by real-time PCR. Results The mean levels of HBV DNA in mothers who had HBV DNA positive children and healthy children were ( 1.2 ×107± 3.1 × 106 ) copies/ml and ( 1.6× 107±8.8×106 ) copies/ml, respec-tively. There was no significant difference between the groups (P >0.05). Meanwhile, viral load in chil-dren was unrelated to that in their mothers (r2 =0.2429). In 11 HBV DNA positive children, 4(36.4% ) demonstrated amino acid substitutions in HBsAg "a" determinant region with 6 different types, I.e. T125A, I126T, Q129H, M133V, D144V and G145A. All of the mothers showed the wild-type sequence in "a" epitope, indicating surface escape mutants were not acquired from the initial infection, but developed under the immune pressure. The mutation rates after immunoprophylaxis for preS1, preS2, S, X, preC/C and P genes were 0.38%, 0. 22%, 0.27%, 0.17%, 0.11%, and 0.11%, respectively, nt2999-3157 in preS1, nt529-677 in S, nt1955-2016 in C, nt923-1001 and nt2489-2602 in P genes were among the hottest muta-tional spots throughout the HBV genome. Conclusion HBV mutation may occur in all the open readingframes after passive and active immunoprophylaxis. In addition to S gene, HBV preS and P genes could alsoassociate with the escape mutants.