Vertical transmission of mouse hepatitis virus infection in mice.

Transplacental infection with mouse hepatitis virus, JHM strain was studied by intravenous inoculation of pregnant dams. Inoculation on day 9 or 12 of gestation brought about the death of more than 50% of the fetuses at 4 days postinfection while inoculation on day 6 or 15 of gestation effected the death of 12% of fetuses or neonates. Inoculation of day 12 of gestation resulted in markedly higher virus titers. At 72 h postinfection in the placentas, fetal membranes and fetuses than in the maternal livers and blood. Virus-specific antigen and virus particles were noted in the placentas, visceral yolk sac and fetal livers by immunofluorescence and electron microscopy. Histopathology revealed degenerative and necrotic changes in these tissues and in the fetal bone marrow.