|Johnson, Nathan - VIRGINIA POLYTECH INST. &|
Submitted to: World Aquaculture Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: October 1, 2006
Publication Date: February 26, 2007
Citation: Palti, Y., Johnson, N., Rexroad III, C.E., Welch, T.J., Wiens, G.D., Silverstein, J., Vallejo, R.L. 2006. Associations of Markers Linked to Major Histocompatibility (MH) Regions and to Other Immune Response Genes with Disease Resistance in Rainbow Trout. World Aquaculture Society Meeting. Technical Abstract: Two disease trials with two gram negative bacterial pathogens were conducted. The 2004 NCCCWA brood year (98 full-sib families) were challenged with Yersinia ruckeri, the causative agent of enteric red mouth disease, and the 2005 brood year (75 full-sib families) were challenged with Flavobacterium psychrophilum, the causative agent of bacterial coldwater disease and rainbow trout fry syndrome. Overall mortality rates were greater than 70% in the F. psychrophilum challenge and greater than 20% in the Y. ruckeri challenge with large variation among families. Resistance to each disease was assessed by monitoring post challenge days to death. Phenotypic variation and additive genetic variation were estimated using mixed models of survival analysis. Microsatellite markers were previously isolated from BAC clones that harbor genes of interest and mapped on to the rainbow trout genetic linkage map. The parents of the 2004 and 2005 brood year families were genotyped with markers linked to the four major histocompatibility (MH) genomic regions, to toll-like receptor (TLR) genes and to the two copies of tumor necrosis factor - super family 13b (TNF-SF13b) to assess linkage disequilibrium between those genomic regions and resistance to the two bacterial diseases. The impact of MH sequence variation on selective breeding for disease resistance in aquaculture is discussed.