Studies on Murine Sarcoma Virus III. Synthesis of the Viral Antigens in Cells of Various Species

The synthesis of murine tumor virus group-specific (GS) and virus envelope (V) antigens following infection of mouse, rat, hamster, chicken, and human cells with mouse sarcoma virus, strain moloney (M-MSV), was studied by immunofluorescence (IF). The two antigens were detected in mouse embryo cells as early as 12–15 hr postinfection (pi), reaching maximal levels at 24–48 hr. An early cytopathic effect (CPE) involving the whole monolayer was constantly present at 24 hr although a fraction only of the cells were actively synthesizing viral antigens. Identical results, except that cellular alteration was absent, were obtained after infection of rat embryo cells; whereas chicken and hamster cells remained totally negative. Infection of human diploid cell lines resulted in the appearance of murine GS and V antigens and CPE 10 days pi. The proportion of antigen-containing cells was observed to decrease in consecutive subcultures.