Localization of gp70 and p30 Murine Type C. Virus Antigens in Thin Section Electron Microscopy Using Novel Immunolatex Spheres and Comparison with Immunoferritin and Immunoperoxidase Methods

Mammalian type C RNA tumor viruses are composed of several structural proteins that can be identified by molecular weight and location on the virion (1). Rauscher leukemia virus (RLV), a murine type C virus, has a 70,000 dalton glycoprotein (gp70) in its envelope and a 30,000 dalton core protein (p30) as two of its major structural proteins (1,2). Synthetic latex microspheres have been shown to be useful surface markers for the scanning electron microscope (SEM) (3). Presented here is a thin section method utilizing novel latex spheres containing aromatic amines which, when coupled to antibodies by diazotization, act as electron-dense markers for indirect immunoelectron microscopic (IEM) detection of gp70 and p30 antigens of RLV. These results are compared with those obtained by immunoferritin and immunoperoxidase methods.RLV-infected murine JLSV-10 cells were used for all IEM. All reactions prior to fixation were carried out at 4°C. Pelleted cells were resuspended in primary serum, either goat anti-RLV p30, goat anti-RLV gp70, or normal goat, and allowed to react for 30 min. Cells were washed and sedimented 3X in buffer. Cell pellets for indirect immunolatex labeling were resuspended and gently agitated for 30 min in donkey anti-goat IgG coupled to latex spheres.