Immunocytochemical localization of gp70 over virus-related submembranous densities in ts mutant Rauscher murine leukemia virus-infected cells at the nonpermissive temperature.

An indirect immunocytochemical labeling technique employing antibody bound to colloidal gold particles as a marker was used to study the distribution of the major viral glycoprotein gp70 on surfaces of cells and virus in cultures infected with wild-type and mutant ts29 Rauscher murine leukemia virus. The temperature-sensitive mutant-infected cells grown at the nonpermissive temperature acquire submembranous densities which are believed to contain the gag gene-coded uncleaved polypeptide precursor. The cell membranes associated with these densities are heavily labeled with the gold-colloid marker and possess much larger quantities of gp70 than the rest of the cell surface. The budding and extracellular virions produced by these cells after shiftdown to the permissive temperature are also heavily labeled. These findings are consistent with the view that structural protein-membrane-glycoprotein interactions are important in type C virus assembly.