Strain-specific degradation of a viral glycoprotein in Newcastle disease virus-infected cells.

In cells infected with mesogenic or lentogenic strain of Newcastle disease virus the level of neuraminidase and hemagglutinin activities sharply decreased after the addition of cycloheximide. With two velogenic strains such decreases did not occur. The infected cells were labelled with 14C-amino acids (leucine or valine) and further incubated with an excess of unlabelled precursor. Polyacrylamide gel analysis revealed a decrease of the peak correspondig to the "large" glycoprotein after the chase in cells infected with meso- or lentogenic strain (Beaudette, B1). In the cells infected with velogenic strains (Italia, Herts) no such decrease was observed. The degradation of the "large" glycoprotein as the cause of the decrease of hemagglutinin and neuraminidase activities in cycloheximide-treated cells and its possible relation to virulence is discussed.