Immune response in progressor and regressor strains of chickens at specific intervals after a primary challenge with Rous sarcoma virus.

A progressor line and a regressor line of chickens were compared for development of immune response, after an initial inoculation of Rous sarcoma virus in the wing-web. Quantitative measures of immunity were determined for the two contrasting lines of chickens at specific intervals after the initial challenge. It was found that subsequent challenges, with either Rous sarcoma virus or tumor homogenate, in the opposite wing-web were met by an early immune response from the regressor line. This early response was absent in the progressor line. However, both lines showed a similar immune response after a time interval of 15 days from the initial challenge. The genes for regression exert this early immune response which is the key to spontaneous regression of Rous sarcomas.