Protection of Chick Against Rous Sarcoma Virus by Serum from Adult Chickens. ∗

Abstract

Discussion and Summary

Whatever vascular cells are affected, the induction of hemorrhagic lesions by the Rous virus indicates extreme susceptibility such as that usually found in the chick. 3 The present results show that adequate treatment of such hosts by serum from adult chickens—presumably through the antibody-like factor there present—causes either a shifting from hemorrhagic into neo-plastic lesions or suppression of all lesions. In other words the treated chicks react to the virus much as adult chickens do. This goes to show that in fowls the age differences in the response to the Rous virus are dependent upon factors in the blood, and confirms the supposition that the relative ineffectiveness of the virus upon the vascular system of the adult is due to the selective protection by the blood of the susceptible cells of the vascular wall whereas the susceptible extra-vascular cells are less protected. Presumably these cells in the chick are still less protected since after an injection of virus, large tumors always arise from them. 2 The present results show that treatment with adult's serum is also effective in protecting these extravascular cells as long as the virus has been injected in the tissues in very small amounts, as presumably happens in the procedure of the intravenous injection. or when the chicks have been prepared for several days before larger amounts of virus were injected intradermally.