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Title: HIGHER RESOLUTION MAPPING AND IDENTIFICATION OF NEW QUANTITATIVE TRAIT LOCI(QTL) AFFECTING SUSCEPTIBILITY TO MAREK'S DISEASE

Author
item Yonash, Nissim
item Bacon, Larry
item Witter, Richard
item Cheng, Hans

Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Marek's disease (MD) is an economically important disease of chickens. Currently, vaccines have controlled the problem but new emerging strains of the disease-causing virus that vaccines cannot control are being encountered more frequently. To help combat MD, chickens are being selected for genetic resistance. Biotechnology may greatly enhance the rate of poultry breeding improvement by identifying the genes responsible for conferring resistance. Building on previous work, this study resolved further 4 regions in the chicken genome that contain MD-resistance genes. In addition, 3 new regions were identified. As a result, genetic markers can be used to generate more disease-resistant chickens. Ultimately, the consumer will benefit as losses due to disease are reduced.

Technical Abstract: Marek's disease (MD) is a lymphoproliferative disease of chickens that costs the poultry inducstry $1 billion annually. Genetic resistance is gaining increased attention to augment vaccinal control as disease outbreaks occur more frequently. Previously, using a 272 F2 white leghorn resource population measured for many MD traits and 78 microsatellite markers, two and four quantitative trait loci (QTL) with significant and suggestive association to one or more MD associated traits, respectively, were revealed. As the chicken genetic maps have improved since the initial study, additional genetic markers were scored on the MD resource population to increase QTL resolution and genome coverage. Saturation of four of the QTL regions with 17 markers revealed five new QTL while 32 markers extended the genome coverage by 400+ cM and uncovered three more QTL. QTL analysis by single-point and interval mapping algorithms agree well when marker saturation is -20cM or less. Currently 127 genetic markers cover -68% of the genome that contain 14 MD QTL associated to one or more MD traits; seven at the significant level and seven at the suggestive level. Individually each QTL accounts for 2 to 7% of the variation and, in general resistance is dominant through the resistant allele may come from either parental line.