In vitro curing of persistent infection of HVJ (sendai virus) carrier tumor cells by spleen cells.

The viral antigens of hamster tumor cells persistently infected with HVJ (Sendai virus) disappeared upon transplantation, showing that HVJ persistent infection can be cured in vivo. In order to analyze these phenomena, an attempt to achieve a similar cure in vitro was made. When HVJ carrier tumor cells (GM2-HVJpi) were cultured in the presence of sera from GM2-HVJpi- tumor-bearing hamsters or rabbit antiserum against glycoproteins (GP) of HVJ, the cells showed only weak stainability with fluorescent antibody (FA). Lymphokines produced by spleen cells from GM2-HVJpi-tumor bearers could not cause GM2-HVJpi cells to lose their viral antigens. However, the viral antigens of GM2-HVJpi cells became undetectable upon cocultivation with spleen cells from either normal of GM2-HVJpi tumor-bearing hamsters. These cells from which HVJ antigens had been lost were reconfirmed to be cured in vitro through single colony isolation and subsequent establishment of a new HVJ infection after superinfection of the isolated cells with HVJ. The above results indicate that the curing of virus persistent infections in HVJ carrier tumor cells by transplantation was due to the in vivo action of spleen cells against transplanted HVJ carrier tumor cells.