Effects on ovine fetuses of exposure to ovine progressive pneumonia virus.

Fetuses of 20 pregnant ewes at 4 gestational periods (45, 55, 85, and 100 days) were inoculated with ovine progressive pneumonia virus. Fourteen of 16 fetuses exposed to virus before gestational day 80 were either resorbed or expelled, whereas 10 of 15 fetuses exposed to virus after day 80 were normal at birth. Three of the 9 expelled fetuses and 1 of 2 newborn lambs had accumulations of lymphoid cells in the lungs. Virus was readily isolated from the tissues of expelled fetuses and newborn lambs. Lambs did not have precipitating antibody to the virus at birth, but 3 to 5 lambs had specific antiviral antibody at 18 months of age.