Marek's disease (MD) is a highly contagious and economically important disease in the poultry industry. It is caused by an oncogenic avian herpes virus. The ability of the virus to evolve into new strains is a continual threat. Vaccination, proper management and genetic resistance are required to completely eliminate the pathogen. The discovery of several markers associated with MD resistance shows that genetic selection for resistance is feasible. Our objective was to identify markers in QTL regions that are associated with MD viraemia. The markers analysed were in the ODC gene, the GH gene and two chemokine genes, all of which are candidate genes for immune responsiveness. A database in a commercial strain of White Leghorn chickens was created. Heterozygous males and homozygous females were identified. The offspring were challenged with MD virus and spleen and thymus samples were collected six days after infection. The viral titre was quantified using competitive PCR. The data was analysed using non-parametric statistics. We found that the paternal alleles of a Hindlll RFLP in the ODC gene were associated with differences in MD viraemia in one of the six sire families analysed. In addition, a Sacl RFLP located in the GH gene also segregated for alleles, which affected MD viraemia. The analysis of the ODC gene was extended to include a second RFLP at a Msp\ site. Together with the Hindlll RFLP it defines three different haplotypes. One genotypic class AB (Hindlll (+/-), Mspl (+/+)) was associated with low vireamia in the thymus and the genotype BB (Hindlll (-/-), Mspl (+/+)) with high viraemia in the spleen. The result suggests that genetic variations in the ODC and GH gene affect MD viraemia. However, we cannot exclude that the observed effects might be due to linkage disequilibrium with adjacent genes. In the latter case, chromosome 3 and chromosome 1, which harbour the ODC and GH gene respectively, must segregate for regions that affect viraemia. The markers identified in this analysis can be used in marker assisted selection.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.19691 |
| Date | January 2003 |
| Creators | Masilamani, Twinkle Jasmine |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Animal Science) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002022778, Theses scanned by McGill Library. |
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