Submitted to: Proceedings of the European Breeders Roundtable
Publication Type: Proceedings
Publication Acceptance Date: September 1, 1997
Publication Date: N/A
Technical Abstract: Marek's disease (MD) is the primary persistent disease problem in poultry. Chickens infected with the Marek's disease virus (MDV) commonly exhibit paralysis, blindness, and visible lymphoid tumors that result in reduced productivity or condemnation. Although vaccines can control MD, the emergence of highly virulent strains that evade current vaccines point to the need for alternative strategies such as genetic resistance as part of long-term solution. Using the chicken genetic map, the chicken genome was scanned for non-MHC quantitative trait loci (QTL) conferring resistance to MD. First, a resource population consisting 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 one 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 .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 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 to high 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.