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SummaryEvidence of infection with noncytopathogenic BVD virus was detected in 5 of 147 live apparently healthy bovine fetuses collected from slaughter cows. Infection was determined by virus isolation from tissues of 3 fetuses and by the presence of neutralizing antibody in the serum of 2 others. One of the 3 fetuses with virus present had antibody also. Noncytopathogenic BVD virus was isolated from placentomes associated with 2 of 3 fetuses from which virus was isolated. Neutralizing antibody was not detected in the serum of a cow carrying an infected fetus. Antibodies to BVD virus were detected in sera from 86.9% of the dams. Although antibodies to IBR virus were detected in 67.0~o and to PI-3 virus in 100.0% of sera tested from dams, no evidence of fetal infection with these viruses was found.Factors affecting the frequency and outcome of infection of the bovine fetus were discussed in relation to 14 recognized viral entities.

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