[Study on the mechanism of intrauterine infection of hepatitis B virus].

OBJECTIVE

To study the possible mechanism of intrauterine infection of hepatitis B virus (HBV).

METHODS

HBV DNA was examined in amniotic fluid, and vaginal secretion of 59 HBsAg positive mothers and in cord blood of their neonates by PCR. Ten negative hepatitis B virus marker (HBVM) mothers and their neonates were served as control. HBsAg and HBcAg in placenta were examined by avidin biotin complex (ABC) method.

RESULTS

The detection rate of HBV DNA in amniotic fluid, vaginal secretion and neonatal cord blood of the study group were 47.5% (28/59), 52.5% (31/59) and 45.8% (27/59) respectively. HBsAg and HBcAg in placenta was distributed in the following descending order: maternal decidual cells, trophoblastic cells, villous mesenchymal cells and villous capillary endothelial cells. But the distribution was in reverse order in 4 placentas. HBsAg and HBcAg were detected in amniotic epithelial cells in 32 mothers.

CONCLUSION

The main route of HBV transmission from mother to fetus is transplacental, from maternal side of placenta to fetal side. However, HBV intrauterine infection may take place through other routes.