Abstract
Cells infected with two closely related isolates of bovine viral diarrhoea virus (BVDV), one cytopathic (CP) and one non-cytopathic (NCP), were examined for signs of apoptosis. The results from labelling DNA using terminal transferase and biotinylated dUTP and by observing oligonucleosomal-sized DNA fragmentation indicated that the CP strain of BVDV induced apoptosis in cell culture but the NCP strain did not. Induction of apoptosis correlated with infected cells undergoing apoptosis rather than interactions between infected and uninfected cells and the induction of apoptosis by CP BVDV was a dominant trait in cells co-infected with both types of virus.