Two groups of 10 pregnant cows were inoculated with bluetongue virus type 11 at either 40 or 60 days of gestation. All the cows became infected as judged by the detection of viraemia and seroconversion but they showed no clinical signs. Seventeen of the cows produced live calves none of which showed any evidence of prenatal infection. After challenge with the same virus all the calves became viraemic and seroconverted. The response to challenge of the two groups did not differ from that of a control group challenged at the same time. It was concluded that the infection of pregnant cows in early gestation with this virus did not result in the transplacental infection of the fetuses and did not produce immunotolerant, latently infected calves.

Non-cytopathogenic pestivirus obtained from lambs with border disease, with or without nervous signs, was inoculated into pregnant ewes at 57 to 65 days of gestation. Live lambs born to inoculated ewes were clinically identical to the lambs from which virus was obtained, ie, either a hairy birth coat with central nervous system disturbance or a hairy birth coat without central nervous system disturbance.