Resistance of BHK21 Hamster Cells to SV40 Papovavirus

Abstract

THE transformation of hamster cells in vitro and in vivo can be readily induced by papovaviruses, polyoma and SV40. The transformed cells are generally characterized by their distinctive morphology, and by their ability to induce tumours when inoculated into normal weanling hamsters, but not when inoculated into hamsters previously injected with the homologous virus^1–7. Normal hamster cells do not produce tumours in hamsters, but Defendi et al.⁸ have reported that as few as 80 cells of a, clone derived from the BHK21 cell line⁹ would induce tumours in hamsters. These cells had not been exposed to either polyoma or SV40 virus. Other clones developed from the same cell line were less tumorigenic. Since these cells were ‘morphologically normal’ and had not been deliberately exposed to viruses, it was of interest to determine whether exposure to SV40 would alter their malignant properties, and whether animals inoculated with SV40 would resist challenge with the BHK21 cells that had been exposed to the virus.