Enhancement of avian sarcoma virus-induced tumor growth after pretreatment with BCG.

Pretreatment of chickens with BCG 1 week before inoculation with avian sarcoma virus had a stimulatory effect on virus-induced tumor growth in 15 of 17 cases tested. This outcome was dependent upon the injection of both BCG and the oncogenic agent into the same wing web. Injection of BCG into the wing web contralateral to that used for virus inoculation or injection of a subcellular fraction of BCG into the same wing web did not affect tumor development. Administration of BCG also gave rise to heightened levels of tumor-associated, cell-mediated immunity, both on the part of chickens which received a subsequent injection of oncogenic virus as well as normal, BCG-inoculated controls.