深圳市乙肝疫苗免疫失败者S基因分析

Analysis of hepatitis B virus S gene of hepatitis B vaccine failures from Shenzhen city

目的了解乙肝疫苗免疫失败者的HBV S基因的变异情况。方法采用流行病学、ELISA与分子生物学方法,筛选乙肝疫苗免疫失败者。采用聚合酶链反应(PCR)、基因克隆和测序的方法,对乙肝疫苗免疫失败者的HBVS基因进行分析,并与HBV参考序列S基因进行比较,分析其变异情况。结果从2 564份受检者中,筛选出2例(0.78‰)HBsAg(-)/HBeAg(+)/HBcAb(+)乙肝疫苗免疫失败者(HBs1、HBs2),经HBV DNA荧光定量PCR检测和HBV S基因PCR扩增,结果均为阳性,为B基因型。其S基因序列与参考序列(JX429908.1)相比,同源性为98.57%,且乙肝疫苗免疫失败者S基因在第363位和第467位分别由野生型的C变为A、G变为A,HBsAg 121位和156位氨基酸C和W缺失。结论乙肝疫苗免疫失败者HBV S基因上第363位和第467位碱基存在错义突变(C→A和G→A),改变了HBsAg的结构和抗原性。

Objective To evaluate the correlation between hepatitis B vaccine failure and S gene mutation. Methods Field epidemiological investigation, ELISA and Molecular biological methods were used to evaluate the hepatitis B vaccine efficacy. Polymerase chain reaction （PCR）, gene cloning and nucleotide sequencing were done to analyze the hepatitis B virus S gene. Results Two cases with an infrequent pattern of HBV serological markers [HBsAg（-）/HBeAg （＋）/HBcAb（＋） ] （0.78%o） were found in 2 564 research subjects. HBV S gene of the hepatitis B vaccine failures were positively identified by PCR,which shared 98.57% sequence homology with HBV S gene from wild type HBV （JX429908.1）. A substitution mutation at the HBV S gene nt363C→A and nt467G→A were found in the hepatitis B vaccine failure, and amino acid C and W at aa121 and aa156 were deletion in HBsAg of hepatitis B vaccine failure. Conclusions HBV S mutants（nt363C--＋A and nt467G→A）were found in two hepatitis B vaccine failures. The mutation may result in a conformational change of the HBsAg and hence affecting its antigenicity.