江西地区儿童感染的乙型肝炎病毒“a”抗原变异分析

The analysis of "a" determinant mutations of Hepatitis B virus infecting children in Jiangxi province

目的:初步分析江西省乙型肝炎疫苗免疫儿童感染的乙型肝炎病毒(Hepatitis B Virus,HBV)"a"抗原决定簇的变异。方法:收集在江西省儿童医院就医的13 117名乙肝疫苗免疫儿童(7.39±3.66岁)血清标本,酶联免疫吸附方法检测HBV-M,抽提HBV表面抗原(HBsAg)阳性血清标本中的HBV DNA,扩增HBV S基因,PCR产物测序并与标准序列对比,分析"a"抗原决定簇的变异与血清型;利用在线Genotyping软件对儿童感染的HBV进行分型。同时用荧光定量PCR检测血清HBV DNA含量。结果:从13 117份血清样品中,检测出HBsAg阳性标本230份(1.75%),扩增HBV S基因并成功测序118份。检测出24份标本有"a"抗原决定簇变异(变异率20.34%),"a"抗原决定簇两茎环间的变异率和男女儿童感染的HBV"a"抗原决定簇的变异率无显著性差异。Q129H、G145A突变后,血清HBV DNA水平较未变异株降低(P<0.05)其他各组则无显著变化。118份测序标本利用Genotyping比对后,112份属于B型,其中adw血清型105份,ayw血清型7份;6份属于C型,均为adr血清型。结论:在江西省乙肝疫苗免疫儿童人群检测出"a"抗原决定簇变异的HBV感染,未发现有明显优势的变异株类型。HBV"a"抗原决定簇区突变对血清HBV DNA含量有一定的影响。

Objective：To analyze the mutation of ＂a＂ dominant in HBV in the vaccinated children in Jiangxi province.Methods：13 117 blood sample from children vaccinated with hepatitis B vaccine were collected in Jiangxi children hospital.HBV-M was tested using ELISA.HBV DNA was extracted from blood sample with positive HBsAg for S gene amplification by PCR.The PCR products were sequenced and compared with standard sequence.Genotype was analyzed using on-line Genotyping.Serum HBV DNA level was measured using Fluorescence quantitative PCR（FQ-PCR）.Results：230 samples with positive HBsAg were detected from 13 117 blood samples（positive rate 1.75%）.S gene was amplified and sequenced in 118 samples among which 24 samples with mutation in ＂a＂ dominant were found（mutation rate 20.34%）.No significant difference in mutations between two loops in ＂a＂ dominant was found.Compared with no mutation group,the serum HBV DNA quantity was lower in Q129H and G145A mutation group,and no significant changes was found in other groups.After sequence alignment with Genotyping,112 sequenced cases were detected to be Genotype B,among which 105 cases of subtype adw and 7 of subtype ayw were found.6 cases of sequence belonged to Genotype C type and were subtype adr.Conclusion：The HBV strains with mutations in ＂a＂ dominant were detected in the infected children with immunization of hepatitis B virus vaccine in Jiangxi province.The mutation sites were scattered and the infection with a dominant mutation type of HBV strain was not found.HBV ＂a＂ mutations have effect on the serum HBV DNA level in chronic hepatitis B patients to a certain extent.