高通量测序分析5例母婴传播中HBV准种变化趋势

Changing trend of HBV quasispecies in 5 cases of mother-infant transmission detected by high-throughput sequencing

目的：探讨5例乙肝疫苗接种失败儿童及其母亲在母婴传播过程中乙型肝炎病毒（hepatitis B virus,HBV）＂a＂决定簇准种变化趋势。方法：选择5例重庆地区乙肝疫苗接种失败的儿童及其母亲,应用PCR法扩增其HBV基因组全长,构建HBV全基因组测序文库后进行solexa高通量测序,并对测序数据进行生物信息学分析。结果：母子HBV序列同源性为99%～100%;5对母子HBV基因型均为B＋C混合型,其中4对优势基因型为B型,1对为C型,母子优势基因型相同;所有儿童均在＂a＂决定簇存在复杂度明显增高位点;5对母子＂a＂决定簇复杂度明显增高的氨基酸（Amino acid,aa）位点共有10个,仅存在于儿童的有2个,为aa126和aa143,儿童中有1例发生优势氨基酸突变,突变形式为G145R。结论：乙肝疫苗接种失败儿童在＂a＂决定簇存在准种现象,儿童体内的突变株可能来源于其母亲。

Objective：To investigate the changing trend of hepatitis B virus （HBV） ＂a＂ determinant quasispecies in 5 children who failed to responded to hepatitis B vaccine and their mothers. Methods：Five children who developed into chronic HBV infection after receiving hepatitis B vaccine and their respective mothers were enrolled into the research. The full HBV genome was amplified by polymerase chain reaction（PCR） and the sequences were determined by Solexa sequencing technology. Results：The sequence homology between paired mother and child was beyond 99%. The HBV genotype in 5 pairs of mother-child was mixture of B and C. Among them, 4 pairs had dominant B while the other 1 pair had dominant C. The dominant HBV genotype was identical between paired mothers and children. Significant complexity positions could be found in every immunized child. There were 10 significant complexity positions in ＂a＂ determinant region in 5 pairs of mother-child;aa126 and aa143 were observed only in one child. And one child had G145R mutant. Conclusion ： ＂a＂ determinant quasispecies can be found in children who failed to responded to hepatitis B vaccine. The mutant strain in child may be transferred from her mother.