EXPERIMENTAL INDUCTION OF MUCOSAL DISEASE - CONSEQUENCES OF SUPERINFECTION OF PERSISTENTLY INFECTED CATTLE WITH DIFFERENT STRAINS OF CYTOPATHOGENIC BOVINE VIRAL DIARRHEA VIRUS

Mucosal disease (MD) can be induced in cattle persistently infected wi th noncytopathogenic bovine viral diarrhea virus (ncp BVD virus) by su perinfecting them with antigenically related cytopathogenic (cp) BVD v irus strains. While some of these animals succumb to early onset MD af ter 2 to 3 weeks post infectionem (p.i.), others only react by produci ng neutralizing antibodies against the cp BVD virus strain and may dev elop late onset MD after longer incubation periods. The aim of this st udy was to determine if an increasing degree of antigenic homology bet ween the ncp and the superinfecting cp BVD virus strains as determined by their comparative reactivity with E2 glycoprotein specific monoclo nal antibodies (mabs) increases the probability of inducing early or l ate onset MD, respectively. For this, each two of eight clinically hea lthy animals from the same herd and persistently infected with the sam e ncp BVD viruses were superinfected with four different cp BVD virus strains. As only two of these animals developed late onset MD, one ani mal from a different herd that developed early onset MD was included i n the study. Besides clinical observation and testing for antibody pro duction, virus isolation and characterization of the cp BVD virus isol ates were performed. The results indicate that antigenic similarity as determined by comparative mab analysis alone is not sufficient to all ow prediction of the outcome of the disease.