Orbivirus infection of the bovine fetus.

Direct inoculation of 85-125 day bovine fetuses with 4 serotypes of bluetongue virus (BTV) or 1 serotype of epizootic hemorrhagic disease virus (EHDV) resulted in either fetal death or teratogenesis. Three serotypes of BTV, and 1 of EHDV caused a similar cavitating encephalopathy, the severity of which likely reflected gestational age of the fetus at infection. Virus-specific antibody was readily detected in precolostral serum samples from all inoculated fetuses that survived until term, whereas, virus was not recovered from any of these calves. Calves with severe Orbivirus induced cerebral malformations would have poor viability, and they could not be expected to have any significance as virus reservoirs.