Correlation of bovine viral diarrhoea virus induced cytopathic effects with expression of a biotype-specific marker

The purpose of this study was the identification antigenic differences between cytopathic (cp) and noncytopathic (ncp) bovine viral diarrhoea viruses (BVDV). Cells infected with 19 strains of each viral biotype were analyzed for reactivity with the monoclonal antibody (mab) BVD/C38. Reactivity was examined using an enzyme immunoassay on fixed infected monolayers of fetal calf kidney cells. In the majority of cases, the mab discriminated between cells infected with each of the two viral biotypes. Three reactivity patterns could be distinguished. Most cpBVDV strains yielded monolayers where 80-100% of infected cells reacted with the mab. Most of the ncpBVDV infected cells showed either no reaction, or only single cells of foci were stained. However, about one third of either cp- or ncpBVDV strains tested yielded infected monolayers where 30-50% of the cells reacted with the antibody. Cell damage other than the typical cytopathic effect might be responsible for the BVD/C38 reactivity of cells infected with BVDV. In addition, it was analyzed whether the antigenic marker associated with cpBVDV was expressed in cells infected with viral isolates from 21 animals with clinical mucosal disease. In 14 cases cpBVDV was isolated and the antigenic marker was found throughout. In seven cases ncpBVDV was cultivated and the antigenic marker was detected in four isolates.