INVESTIGATIONS ON THE EFFICACY OF AN INAC TIVATED BVD VIRUS-VACCINE FOR IMPROVEMENT OF THE SAFETY OF AN ATTENUATED BVD VIRUS-VACCINE

Eight cows received an inactivated BVD vaccine once or twice, respecti vely. Four weeks later a commercial modified BVD live viral vaccine wa s administered. The pregnant cows 60-80 days after artificial insemina tion were challenged naso-orally with 10(4,0) CID50/animal of a non-cy topathogenic BVD virus field isolate (22146/Han81). The challenge appa rently did not lead to a transplacental transmission of BVD virus and infection of the fetuses. Neither BVD virus nor BVD virus neutralising antibodies could be detected in precolostral blood samples of the eig ht clinically healthy new born calves. The results of this trial indic ated that prior to breeding vaccination of cattle using inactivated BV D virus vaccine can (a) lower the risk of detrimental effects of modif ied live viral vaccine and (b) in combination with the latter can prev ent bovine fetuses from transplacental BVD virus infection in the vuln erable stages of gestation.