title: Components involved in virally mediated membrane fusion and permeability changes.
abstract: 1. Intact F glycoprotein is required to induce permeability changes in Lettrée cells or in erythrocytes. Some HN glycoproteins may also be required. Permeability changes thus offer a simple, accurate and rapid means of assaying the integrity of F glycoprotein in certain viral preparations. 2. The '1-day' virus (which contains intact F glycoprotein but which differs morphologically from '3 day' virus) does not cause permeability changes; it can be rendered active by various physical treatments. It is concluded that the environment in which F glycoprotein is embedded is a determining factor for permeability changes. 3. The entry of fluorescently labelled peptides into cells made permeable by virus has been measured. Peptides having a molecular weight in excess of 1000 enter poorly, suggesting a 'pore' size of approx. 1 nm in diameter. 4. Two novel assay methods concerned with virus--cell fusion are described. The first measures the fluorescence enhancement that occurs when anthroylstearate is transferred from anthroylstearate-labelled virus to cells. The second measures the giant-cell formation that occurs when partially fused erythrocytes are exposed to hypo-osmotic treatment. The '1-day' virus is active in these assays. In contrast with permeability changes, virus--cell fusion is insensitive to changes in external Ca2+-concentration. 5. The results are compatible with a model [Knutton & Pasternak (1979) Trends Biochem. Sci. 4, 220--223; Impraim, Foster, Micklem & Pasternak (1980) Biochem. J. 186, 847--860] in which virus--cell fusion is a prerequisite for permeability changes, and in which permeability changes are the cause of haemolysis and giant-cell (polykaryon) formation.
mesh_terms: D002118:Calcium / Q000494:pharmacology; D002459:Cell Fusion / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects*; D002463:Cell Membrane Permeability / Q000187:drug effects; D006023:Glycoproteins / Q000032:analysis / Q000494:pharmacology*; D066298:In Vitro Techniques; D008858:Microscopy, Phase-Contrast; D008954:Models, Biological; D010222:Parainfluenza Virus 1, Human / Q000032:analysis; D013050:Spectrometry, Fluorescence; D014764:Viral Proteins / Q000032:analysis / Q000494:pharmacology*
chemical_list: D006023:Glycoproteins; D014764:Viral Proteins; D002118:Calcium