Genetic analysis of a divergent selection for resistance to Rous sarcomas in chickens†. This article is dedicated to the memory of Pierrick Thoraval (1960–2000).
ABSTRACT Selection for disease resistance related traits is a tool of choice for evidencing and exploring genetic variability and studying
underlying resistance mechanisms. In this framework, chickens originating from a base population, homozygote for the B
19 major histocompatibility complex (MHC) were divergently selected for either progression or regression of tumors induced at
4 weeks of age by a SR-D strain of Rous sarcoma virus (RSV). The first generation of selection was based on a progeny test
and subsequent selections were performed on full-sibs. Data of 18 generations including a total of 2010 birds measured were
analyzed for the tumor profile index (TPI), a synthetic criterion of resistance derived from recording the volume of the tumors
and mortality. Response to selection and heritability of TPI were estimated using a restricted maximum likelihood method with
an animal model. Significant progress was shown in both directions: the lines differing significantly for TPI and mortality
becoming null in the "regressor" line. Heritability of TPI was estimated as 0.49 ± 0.05 and 0.53 ± 0.06 within the progressor
and regressor lines respectively, and 0.46 ± 0.03 when estimated over lines. Preliminary results showed within the progressor
line a possible association between one Rfp-Y type and the growth of tumors.
Rfp - Y