儿童乙型肝炎患者病毒S基因变异及病毒学特征

Virological characterizatics and variations of hepatitis B virus surface antigen gene in child patients

目的探讨湖州地区儿童HBV感染者的病毒学特征和病毒S基因变异情况。方法应用PCR方法对湖州市中心医院住院或门诊收集的38例15岁以下、HBVDNA〉500IU／mL、HBsAg阳性患儿的HBV进行S基因扩增，测序分析扩增产物，同时检测患儿血清HBV标志物、病毒载量和肝功能水平。结果38例患儿中，36例曾接种过乙型肝炎疫苗，占94．74％，抗-HBs阳性仅5例（13．16％），HBeAg阳性31例（81．58％）。测序成功的36例样本中B基因型32例，其中adw血清型29例，ayw型3例；C基因型4例，均为adr血清型。36例测序成功的样本中，14例HBV存在S基因变异（变异组），22例不存在变异（无变异组）。14例样本S基因区共19个位点发生了变异，16处变异发生在B细胞表位，且其中10处发生在aal24～147（a抗原决定簇）内；其余1处发生在T细胞表位内，2处发生在B/T细胞表位以外区域。14例变异者中，抗-HBs阳性者2例（14．29％），AIJT异常者占4例（28．57％），AST异常者2例（14．29％），与无变异组相比，差异无统计学意义（确切概率法，19〉0．05）。变异组HBVDNA载量为（6．92±1．73）IU／mL，低于无变异组的（7．76±1．26）IU／mL，差异无统计学意义（t=1．685，P〉0．05）。结论湖州儿童HBV感染以B型为主，部分感染可能与病毒变异导致的免疫失败有关，病毒S基因变异主要位于B细胞和T细胞表位，特别是a决定簇内。病毒变异与否对患儿血清病毒学及肝功能的影响无明显差异。

Objective To analyze the virological characteristics and variations of surface gene （S gene） in hepatitis B virus （HBV） genome in HBV-infected children in Huzhou. Methods Thirty-eight patients under the age of 15 years with serum HBV DNA〉500 IU/mL and positive HBsAg in Huzhou Central Hospital were enrolled in the study. HBV DNA S gene samples from them were amplified and sequenced by PCR and their serum HBV markers, HBV DNA loads and liver function were also examined. Their serum HBV markers, HBV DNA loads and liver functions were also examined. Results Thirty-six out of 38 patients had HBV vaccinated （94.74%）; 5 chil- dren were anti-HBs positive （13.16%）; 31 cases were HBeAg positive （81.58%）. Out of 36 patients successfully sequenced, 32 were B genotypes （29 with adw, 3 with ayw） and 4 were C genotypes （all were with adr）. There were 19 amino acids variants in 14 positions within S gene, which existed in 14 patients （S gene variation group）. Sixteen amino acids mutations were in B-cell epitope, among which 10 amino acids mutations were in aa124-147 （＂a＂ determinant）; other 1 amino acids mutations were in T-cell epitope, 2 were outside B/T-cell epitope. The rest 22 patients had no HBV DNA variation （non-variation group）. Rate of anti-HBs positive （14.29%, 2/14） and abnormal rate of liver function enzyme levels （ALT： 28.57%, 4/14 and AST： 14.29%, 2/14） were insignificant between S gene variation and non-variation groups（P〉0. 05）. Serum HBV DNA load was（6.92±1.73） IU/mL in S gene variation group and（7.76±1.26） IU/mL in non-variation group, without a significant difference between them （t=1.685,P〉0.05）. Conclusions The B genotype is the major genotype in children with HBV infection in Huzhou. HBV infection may be associated with failure of vaccination caused by HBV escape mutants. S gene variants exist in B-cell and T-cell epitopes, especially in ＂a＂ determinant of S gene region. Viral mutations or not had on different significant between virological characteristics and liver function in children infected with HBV.