Tumour Production in Immunosuppressed Rats with Cells Transformed in vitro by Adenovirus Type 2

Serotypes of human adenovirus have been classified by Huebner (1967) into three groups (A, B and C) based on their oncogenicity in hamsters. Rat cells transformed in vitro by viruses from both groups A and B have been reported to produce tumours in new-born rats (Freeman et al. 1967b, c). Some members of Huebner's non-oncogenic group C were subsequently shown to cause morphological transformation of primary rat embryo cells in vitro (Freeman et al. 1967a; McAllister et al. 1969). Clones derived from these epithelioid foci are similar in their in vitro characteristics to transformed clones induced by adenovirus in groups A and B. The cells grow to high density in medium with low serum, produce colonies in agar and possess adenovirus specific tumour antigen (T-antigen). No tumours were produced when cells transformed in vitro by the group C adenoviruses were inoculated into syngeneic neonate rats and it has been suggested that group C adenoviruses induce strong transplantation antigens in the cells they transform (McAllister et al. 1969).