Relationship between HBV genotype,PreS/S gene mutation and immunoprophylaxis failure to prevent HBV mother-to-child transmission

AIM：To investigate the relationship between hepatitis B virus (HBV) genotype, PreS/S gene mutation and immunoprophylaxis failure to prevent HBV mother-to-child transmission.
METHODS：Pregnant women with positive HBV surface antigen (HBsAg) and HBV DNA≥1×1010 IU/L were divided into case group (15 cases) and control group (45 cases) according to their neonates with immunoprophylaxis failure or not. The genotypes of HBV and the mutation rate and mutational hot spots in PreS/S gene were detected by PCR amplification technique in the two groups.
RESULTS：(1) Genotypes B and C of HBV were detected in both case and control groups, and the majority of HBV genotype was B in the two groups. Genotype distribution difference between case and control groups was not statistically significant (P>0.05). (2) There was no significant difference in the mutation rate of PreS/S gene between case and control groups (P>0.05). The mutation rates of PreS/S gene between genotypes B and C were significantly different (P<0.05), but when the HBV genotype was the same, the mutation rate of PreS/S gene had no significant difference between case and control groups. Homology tree model based on PreS2/S gene formed genotype B and genotype C clusters, and in each cluster, the sequences of case and control groups did not formed smaller different clusters further. (3) 529G-A, 530A-G, 826A-G1 and 166het-dupC were hot spots of mutation in PreS2/S gene and were found in 4 cases in case group, respectively. A530T (1 case), A530G (2 cases), T531C (3 cases) were found in control group.
CONCLUSION：(1) The mutation rates of PreS/S gene are different in various genotypes. (2) The mutation in PreS/S gene of HBV is prevalent, but not all of the mutations are related to immunoprophylaxis failure to prevent HBV mother-to-child transmission. To find mutational hot spots which are related to immunoprophylaxis failure is more important.