Transplacental Japanese encephalitis virus (JEV) infection in mice during consecutive pregnancies

Transplacental transmission of Japanese encephalitis virus (JEV) has been demonstrated in consecutive pregnancies of mice. Pregnant mice inoculated intraperitoneally with JEV transmit the virus to the foetus. When such female mice were mated again after 6 months, the virus could be isolated from the foetuses of the ensuing pregnancy. The incidence of abortion was increased significantly though the neonatal deaths were considerably less than during the first pregnancy. Intra-uterine infection occurred in spite of the presence of HAI antibodies against JEV in the preconceptional sera of the mice. The findings of the present study indicate the value of such a system for further investigations of the pathogenesis of JEV infection during pregnancy in humans.