Characteristics of Gross virus-induced leukemia cell clones. II. Oncornavirus production

Oncornavirus production differed quantitatively among four Gross virus-induced murine leukemia clones. To determine the proportion of cells in each clone that were producing virus particles, the cells were stained by indirect immunofluorescence with antiserum to Gross antigen. All four clones had the same percentage of cells positive for the presence of Gross antigens irrespective of their ability to produce virus particles. A direct correlation was observed between the amount of RNA tumor virus attached to the plasma membrane and agglutination by concanavalin A. The leukemia strain that produced the most virus also had the greatest degree of agglutination. Oncornavirus production was indirectly related to oncogenicity of the cells in vivo: The clones that produced the most virus were the least malignant. The interaction of the host and virus-producing cells was monitored during animal passage, and virus production decreased during animal passage whereas transplantability increased.