Pathogenesis of mucosal disease and molecular aspects of bovine virus diarrhoea virus.

Studies carried out over three decades, on the pathogenesis and epidemiology of bovine virus diarrhoea virus (BVDV), have provided the basis for our understanding of the aetiology of mucosal disease. Experimental reproduction of the disease has demonstrated the mechanism of sequential infection and the role of the two virus biotypes. The need for "homogeneity" between the biotypes, causing mucosal disease, has demonstrated the precision of immunotolerance. The origin of the cytopathogenic biotype remains unclear but molecular studies may provide the solution. Recent findings have revealed the absence of an 80 kDa polypeptide in the non-cytopathogenic isolates. This protein is related to the 120 kDa polypeptide that is present in both biotypes. Genomic sequences for two isolates have been reported. An extensive homology to the protein ubiquitin has been identified only within the Osloss sequence in the region flanking coding sequences for the 80 kDa and 120 kDa proteins. Advances in the development of molecular gene probes and monoclonal antibodies will provide new tools for furthering our understanding of the pathogenesis, epidemiology and interrelationships of pestiviruses that infect pigs, cattle and sheep.