Electron microscope study of cultured cells of the chorioallantoic membrane infected with representative paramyxoviruses

Abstract

Chorioallantoic membrane (CAM) tissue cultures were found to be permissive for representative paramyxoviruses. The CAM cells can be used for plaque assay without the presence of trypsin. Ultrastructures of CAM cells infected with paramyxovirus Yucaipa (PMY), Sendai virus, and NDV were different. Nucleocapsids were readily seen in budding structures of cells infected with PMY, and in Sendai virus infected cells, large clusters of nucleocapsids were clearly evident in the cytoplasm. The site of glycoprotein cleavage does not have any effect on the nature of budding. It appears that a factor or factors in addition to the nature of the plasma membrane influences the morphology of cells infected with paramyxoviruses.

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

“…We have shown that cleavage of the glycoproteins occurred in CAM-cells infected with NDV, PMY, and Sendal virus, which is consistent with the plaque forming ability (infectivity) of these viruses in CAM-ceils (10,18). Cleavage was not complete for the glyeoproteins of all of the strains tested, owing to the presence of CEF cells in the cultured CAM-cells.…”

“…The use of CAM-cells, previously found to be permissive for representative paramyxoviruses (18), facilitated experimentation on the comparative biosynthesis of the viral glyeoproteins in infected cells. CAM-celts fulfilled the objective of using the same eel1 system for different paramyxoviruses.…”

“…We reported that CAM-cells are permissive (based on plaque forming ability) for Sendai virus and PMY (18). Avirulent NDV strains were found to form plaques in CAM-cells (10).…”

“…I n the present investigation we have used the CAM cultured cells (3), recently reported to be permissive for Sendai virus and PMY (18), to determine the site of cleavage of F0 and the biosynthesis of polypeptides of representative p a r a m y x oviruses in CAM cells. We were specifically interested in whether a " t h i r d " glyeoprotein, designated large glycoprotein (LGP) and present in egg-grown virus, is virus specific (4).…”

Changes in specific cleavability of the Sendai virus fusion protein: implications for pathogenicity in mice

“…Post-translational proteolytic cleavage of the envelope fusion (F) glycoprotein into subunits F~ and F2 is a prerequisite for the virus to express infectivity (Homma & Ohuchi, 1973;Scheid & Choppin, 1974). The cleavage site at amino acid position 116 is composed of a single arginine residue, which is not cleaved by cellular proteases of most cell types, but is cleaved by trypsin (EC 3.4.21.4), a trypsin-like endoprotease present in embryonated chicken eggs (Gotoh et al, 1990;Muramatsu & Homma, 1980;Suzuki et al, 1991) and by host proteases in primary cell cultures (Seto et al, 1980;Shibuta et al, 1971 ;Silver et al, 1978) and in the lungs of mice (Tashiro & Homma, 1983 a, b;Tashiro et al, 1990).…”