Immunopathogenicity and oncogenicity of murine leukemia virus. III. Quantitation of spontaneous virus expression.

Electron microscopic determination of C-type virions in gut-associated and genital tract epithelia was made in various murine strains. The number of morphologically identifiable C-type virus particles varied more than 100-fold among strains, being high in all strains exhibiting immunologic disease, as well as several immunologically normal strains, and low in other immunologically normal strains. No relationship was seen between the number of virions found in epithelial and lymphoid tissues. There was, however, a direct correlation between numbers of virions in epithelial tissues and levels of serum gp70.