The site of cleavage in infected cells and polypeptides of representative paramyxoviruses grown in cultured cells of the chorioallantoic membrane.

Cultured cells of the chorioallantoic membrane (CAM) fulfilled the need of using the same cell system that was permissive for representative paramyxoviruses to carry out studies on the biosynthesis of their glycoproteins in infected cells. The polypeptides composition of the respective paramyxoviruses [Newcastle disease virus (NDV), paramyxovirus Yucaipa (PMY), and Sendai virus], grown in eggs and CAM-cells, was essentially identical. In egg-grown PMY a large glycoprotein (LGP) was present but only in some CAM-grown preparations of virus labeled with [3H]-glucosamine and rarely in [35S]-methionine or [3H]-amino acids (valine, leucine, and tyrosine) labeled viruses. The site of cleavage of precursor F0 to F1,2 was not the same. In contrast to the cleavage of Sendai virus glycoprotein, cleavage was intracellular in NDV and PMY infected cells. Homologous antisera against the glycoproteins failed to inhibit cleavage of HN0 or F0 in cells infected with the representative paramyxoviruses.