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

Eight cows received an inactivated BVD vaccine once or twice, respectively. Four weeks later a commercial modified BVD live viral vaccine was administered. The pregnant cows 60-80 days after artificial insemination were challenged naso-orally with 10(4,0) CID50/animal of a non-cytopathogenic BVD virus field isolate (22146/Han81). The challenge apparently 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 eight clinically healthy new born calves. The results of this trial indicated that prior to breeding vaccination of cattle using inactivated BVD virus vaccine can (a) lower the risk of detrimental effects of modified live viral vaccine and (b) in combination with the latter can prevent bovine fetuses from transplacental BVD virus infection in the vulnerable stages of gestation.