Variation in the intracellular polypeptide profiles from different isolates of bovine virus diarrhoea virus

Variation of the intracellular polypeptides induced in calf testis cells by 5 cloned isolates of bovine virus diarrhoea virus (BVDV) was examined. Three of the isolates were cytopathic (NADL, C 2415 and Pe 515 c) and two were non-cytopathic (C 1226 and Pe 515 nc) in these cells. The isolates Pe 515 c and Pe 515 nc were both isolated from an animal with clinical signs of mucosal disease. In cells infected with NADL, 8 virus specific proteins (vp 1 to vp 8) with molecular weights ranging from 120,000 (vp 1) to 23,000 (vp 8) were detected. Isolates C 2415 and Pe 515 c gave a similar array of polypeptides to NADL, but the 3 cytopathic isolates could be distinguished by the variation in the molecular weights of some of the proteins. The non-cytopathic isolates could also be distinguished from each other by this type of molecular variation; however, one feature that characterised these strains, when compared to the cytopathic isolates, was the absence of vp 2. Comparison of the polypeptides induced by Pe 515 c and Pe 515 nc showed that apart from the lack of vp 2 in the Pe 515 nc virus profile, the molecular weights of the other viral proteins were similar. This supports serological evidence that for mucosal disease to occur the pair of cytopathic and non-cytopathic viruses must be closely related. Four of the polypeptides induced by Pe 515 c were shown to be glycoproteins.