Study Of The Mechanism Of Intrauterine Transmission Of Hepatitis B Virus

Objective To study the possible mechanism of intrauterine infection of hepatitis B virus.Methods 88 cases of Hepatitis B virus surface Antigen (HBsAg) positive mothers were served as HBV group. 25 negative hepatitis B virus marker (HBV-M) mothers were served as control group .HBV-DNA was examined in serum of 88 HBsAg positive mothers and in cord blood of their neonates by PCR. Bcl-2, Bax and HBcAg expression in placenta were detected by immunohistochemistry method .Results The detection rates of HBV DNA in serum and neonatal cord blood of the study group were 35.23% and 21.59%, respectively,The HBV-DNA detection rate of neonatal cord blood in mothers' serum HBV-DNA positive group was 61.29%.it was 0% in control group. There was significant difference between two groups (p<0.05) .HBcAg was mainly located in the cytoplasm of infected placenta cells. HBcAg in placenta was distributed in the following descending order: HBV infection rates in trophoblastic cells(TC),villous mesenchymal cells (VMC) and villous capillary endothelial cells (VCEC) were 48.86%, 20.45% and 9.09%.Significant difference of Bax expression was found in study positive group and control group (p=0.005＜0.05),but no differences in bcl-2 expression (p=0.721＞0.05).Conclusions (1) The main route of HBV transmission from mother to fetus is transplacental. There is a closed relationship between intrauterine infection rate and HBV-DNA concentration. (2) HBcAg was found in different placentas cells of HBsAg positive pregnant women from maternal side of placenta to fetal side. (3) The high expression of Bax in HBV infectious placental cells suggests that HBV infection might relate with cell apoptosis.