Submitted to: Workshop on Molecular Pathogenesis of Marek's Disease and Avian Immunology
Publication Type: Abstract Only
Publication Acceptance Date: August 5, 2006
Publication Date: August 5, 2006
Citation: Zhang, H.M., Dunn, J.R., Heidari, M., Witter, R.L., Kulkarni, G., Bacon, L.D. 2006. The threshold of genetic susceptibility to Marek's disease [abstract]. 4th International Workshop on Molecular Pathogenesis of Marek's Disease Virus. p. 33. Technical Abstract: The threshold of genetic susceptibility to Marek’s disease (MD) varies between lines of chickens due to genomic differences between the lines. For instance, one inbred line, 63, has a high threshold of susceptibility to MD, whereas another inbred line, 72, has a low threshold; both of the lines were selected and are maintained at the Avian Disease and Oncology Laboratory. Recent genome-wide SNP-typing data show that 19% of a SNP panel differs between lines 63 and 72. Genes representing or residing near 19% of the SNPs are likely to be responsible for the thresholds of susceptibility to MD in the two lines. In two consecutive trials, none of line 63 and 100% of line 72 chickens developed MD tumors following inoculation with a partially attenuated vv+ MDV strain (648A, passage 40), confirming the difference in thresholds of genetic susceptibility to MD in the two lines. However, a lower passage of 648A (passage 30)induced tumors in 50% of line 63 chickens affirming that the threshold of genetic susceptibility to MD is determined not only by the genome of the chicken line, but also by the pathogenicity of the challenging virus. More interestingly, data from two separate trials using MDV 648A passage 40 and 584A passage 20, another partially attenuated vv+ MDV, showed different ranks of MD incidences among a series of 19 recombinant congenic strains (RCS) of the two inbred lines (on average, each of the 19 RCS is 87.5% and 12.5% identical to the line 63 and 72 genome, respectively). For instance, one of the RCS was ranked among the lowest tumor incidence (0%) when infected by 648A passage 40 but the highest (100%) when infected by 584A passage 20. The inconsistency between the ranking of the series of recombinant congenic strains based on MD incidences induced by MDV 648A passage 40 and the ranking by MDV 584A passage 20 provides preliminary evidence of host and pathogen genome-specific interactions that may further alter the threshold of genetic susceptibility to MD in chickens.