以4名HBsAg、HBeAg 均阳性的女性携带者及其子宫内感染HBV 的4 例胎儿为对象,研究母儿间病毒的基因分型与S区变异株。以双脱氧链末端终止法检测母儿所携HBVS区451～660 位核苷酸序列。母儿间同源性98% ～100% ,检出530、546、581位点变异致使126 位、131 位、143 位氨基酸替代。根据当前的基因分型方法, 2对母儿均为B型, 2对母儿母亲为B型, 胎儿为A、B混合型。HBV 子宫内传播存在S基因变异株。母儿间基因型别基本一致 Four female fetuses with positive HBsAg and HBeAg and four fetuses infected with HBV in their uterus were studied for genotyping and S region mutants. The nucleotide sequence of 451 ~ 660 nucleotides in HBVS harboring maternal and females was detected by dideoxy chain termination method. The homology between maternal and child was 98% ~ 100%. A total of 530,546,581 loci were detected, which resulted in the substitution of 126th, 131th and 143th amino acids. According to the current genotyping method, 2 pairs of mother and child are type B, 2 pairs mother and mother is type B, fetal A, B mixed type. HBV intrauterine transmission of S gene variants exist. Mother and child genotypes are basically the same