Trichinella spiralis as a modulator of Shope fibroma virus.

After the works on the promoting effect of trichinellosis on some viral infections in rodents, many studies successively demonstrated that Trichinella spiralis confers resistance to many unrelated antigens including pathogens, such as Protozoa, Bacteria and tumour cells (B16 melanoma). Considering the above contradictory results, the present work was undertaken to study, in rabbits, T. spiralis as a modulator of Shope's fibroma virus, an oncogenic virus responsible for a benign neoplasia. Four groups of 6 rabbits each were used. The rabbits of group I, II and III were inoculated per os with 3000; 6000 and 12,000 T. spiralis larvae, respectively. The rabbits of group IV were used as controls. Thirty-five days after the inoculation, all the animals were injected at the fixed doses of 0.5 ml with dilutions (10(-1) to 10(-8] of Shope's fibroma virus given intradermally into 8 different points of the skin of each pretreated and untreated rabbits. After 9 days tumour lesions affecting the inoculating area were noticed and the DI 50/0.5 of Shope's fibroma virus was then determined for each of the 4 experimental groups. The rabbits pretreated with T. spiralis exhibited much lower virus titres than the controls, which was evidently related to a certain degree of aspecific immunity conferred by the parasite. The results indicated that T. spiralis produces, in rabbits, resistance to Shope's fibroma virus and its neoplastic effect.