Resistance to Murine Tumors Conferred by Chronic Infection with Intracellular Protozoa, Toxoplasma gondii and Besnoitia jellisoni

Abstract

Toxoplasma gondii, a common latent intracellular parasite of man, has been shown to confer resistance against intracellular bacteria (e.g., Listeria) and virus (e.g., Mengo) in mice. Since this resistance is mediated by cells and persists for more than one year, it was pertinent to determine if Toxoplasma gondii and a related protozoan, Besnoitia jellisoni confer resistance against transplantable and autochthonus tumors. Significant resistance to development of mammary tumors was noted in C₃H/_He mice and to leukemia in AKR mice. Similar resistance was noted following challenge with Friend leukemia virus and sarcoma 180 in Swiss-Webster mice.