Detection of viral antigen in placenta and fetus of cattle acutely infected with bovine viral diarrhea virus

The reproductive organs and fetuses of seven Norwegian Red heifers were inv estigated for the presence of bovine viral diarrhea virus (BVDV) antigen du ring the time of initial transplacental transmission of the virus. The heif ers were inoculated with a noncytopathogenic BVDV at day 85/86 of gestation and were slaughtered at day 7, 10, 14, 18, or 22 postinoculation (pi). Cry ostat sections of uterus, ovaries, placentomes, intercotyledonary fetal mem branes, and fetal organs were examined using immunohistochemical techniques . A double immunofluorescence technique was used to identify cells that sho wed staining with antibodies against the leukocyte common antigen CD45 or t he intermediate filament vimentin and BVDV antigens. The earliest stage of infection at which BVDV antigen could be detected in the fetuses was 14 day s pi. At this stage, BVDV antigen was detected in cells of mesenchymal orig in in the lungs and in large cells that morphologically resembled immature megakaryocytes in the liver. In the intercotyledonary fetal membranes and i n the placentomes, BVDV antigen was not detected until 18 and 22 days pi, r espectively. BVDV antigen was not detected in maternal tissue from any of t he heifers. The present results indicate that fetal infection with BVDV can rake place without preceding or simultaneous high concentrations of BVDV i n uterus or placenta of acutely infected heifers.