Characterization of Sarcoma-Positive,Leukemia-Negative (S - L - ) Human CeIIs Induced by the Feline Leukemia Virus Pseudotype of Moloney Sarcoma Virus

Abstract

Human osteosarcoma clonal cells (TE-85 clone F-5) can be readily transformed by the feline leukemia virus pseudotype of Moloney sarcoma virus [Mo-MSV (FeLV)]. Among a number of foci isolated at limiting Mo-MSV (FeLV) dilution four clones of sarcoma-positive, leukemia-negative (S⁺L^-) cells were selected and characterized. These clones were negative for infectious virus and type C virus particles; however, they contained a rescuable MSV genome and murine leukemia virus (MuLV)-specific antigen, such as the gag gene products, p15, p 12, and p30, but lacked the env gene protein (gp 70). S⁺L^- clones were all tumorigenic in nude mice. The Mo-MSV rescued by baboon type C virus (M-7), Mo-MSV(M-7), produced foci readily in human, NRK, and NIH 3T3 mouse embryo cells. Human cells transformed by Mo-MSV(M-7) were found to be virus producers; whereas Mo-MSV (M-7)-transformed NRK and NIH 3T3 mouse embryo cells were found to be S⁺L cells. These rat- and mouse-transformed cells were negative for infectious virus but they contained a rescuable MSV genome and MuLV antigen.