Submitted to: Molecular Genetics & Breeding for Disease and Insect Resistance in Crops &
Publication Type: Proceedings
Publication Acceptance Date: November 14, 1997
Publication Date: N/A
Technical Abstract: Marek's disease (MD) is a major problem for the poultry industry. Chickens infected with the Marek's disease virus (MDV) exhibit paralysis, blindness, and lymphoid tumors that result in reduced productivity or condemnation. The increasing appearance of highly virulent strains that evade vaccines point to the need for strategies such as genetic resistance as part of the long-term solution. To identify non-MHC quantitative trait loci (QTL) conferring resistance to MD, the chicken genome was scanned using genetic markers from the chicken genetic map. First, a resource population of 300+ F2 chickens from the inbred lines 63 (MD resistant) and 72 (MD susceptible) was generated; all chicks were challenged with JM strain MDV at 1 week of age and monitored for symptoms of MD. Second, 65 DNA markers covering 1900+ cM of the chicken genome were genotyped on the 40 most susceptible and resistant chickens and 21 suggestive markers (P less than or equal to 0.20) were revealed. Next, the suggestive markers plus flanking markers were typed on 272 chickens and, using a suite of interval mapping programs, 8 genomic regions containing QTL affecting several components of MD susceptibility were identified. To eliminate ambiguities in the statistical data, additional markers were added which helped resolve the location of several QTL. To fine-map and characterize these QTL, recombinant congenic strains are under development using lines 63 and 72 as the recurrent parent and donor strains, respectively, and in our preliminary experiments, 3 of the 19 lines show moderate levels of MD incidence. These studies shed light on the multigenic basis of MD resistance and the possibility of using marker-assisted selection for improvement of genetic resistance in the chicken.