Clinical and laboratorial findings in pregnant ewes and their progeny infected with Border disease virus (BDV-4 genotype)

To evaluate the pathogenicity of local isolates of ovine pestiviruses (BDV-4 genotype), 13 virus- and antibody-negative, artificially inseminated pregnant ewes were challenged on days 108 (5 ewes), 76 (5 ewes) and 55 of pregnancy (3 ewes) with 2 ml of ovine pestivirus containing 10⁶ TCID₅₀. Viraemia was detected by RT-PCR from 2 to 15 days pi in most ewes. No abortion due to the infection was observed but the number of stillbirths was high (32%), and bodyweight at lambing was significantly reduced compared to the experimental flock of origin used as control. Clinical symptoms in live lambs consisted on tremors, gait anomalies and inability to stand unaided. Skeletal abnormalities (brachygnathia, prognathia, arthrogryposis) were present in 44% of the lambs. Only 20% of the lambs were clinically normal. RT-PCR was a very sensitive technique compared to antigen ELISA in detecting viral presence in experimentally infected ewes and their progeny.