Comparison of the immunogenicity of hamster cells transformed by adenovirus and Herpes simplex virus.

Hamsters vaccinated with adenovirus-transformed cells, modified by acetoacetylation or concanavalin A treatment, or with small numbers of living cells were partly or completely protected against challenge with 3 times 10-6 living cells. Treatment of vaccine cells with iodoacetate, Mitomycin C, neuraminidase plus Mitomycin C did not produce efficient vaccines. Herpes simplex virus-transformed cells treated by any of these procedures did not prevent, and frequently even enhanced, the growth of the homologous living cells; enhancement was often greater in female than in male hamsters. Protective and enhancing vaccines did not induce a different level of cell-mediated immunity, as detected by lymphocytotoxicity tests, which were positive for both homologous transformed cells and nontransformed hamster cells. In contrast, specific complement-dependent cytotoxic antibodies active only on adenovirus-transformed cells were induced by the protective acetoacetylated vaccine prepared from adenovirus-transformed cells; these antibodies were not present after nonprotective vaccinations. The appearance of herpes simplex virus tumors was delayed by treatment with the immunostimulant, Levamisole, or by preimmunization with Newcastle disease virus grown in SV40-transformed cells, but not by Newcastle disease virus grown in herpes simplex virus-transformed cells. Thus, only nonspecific treatments were able to impede herpes simplex virus tumor growth, while protection against adenovirus tumor was accompanied by specific cytotoxic antibodies.