|Wiens, Gregory - Greg|
|Leeds, Timothy - Tim|
|Welch, Timothy - Tim|
Submitted to: Flavobacterium Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 6/19/2009
Publication Date: 9/23/2009
Citation: Wiens, G.D., Leeds, T.D., Vallejo, R.L., Palti, Y., Welch, T.J., Rexroad Iii, C.E. 2009. Resistance of rainbow trout to Flavobacterium psychrophilum infection: integrating selective breeding and microbial genomics. Flavobacterium 2009 Meeting. Paper No. 100.
Technical Abstract: Bacterial cold water disease (BCWD) is a frequent cause of elevated loss in juvenile salmonid fish and development of effective control strategies is a priority. At the National Center for Cool and Cold Water Aquaculture (NCCCWA), we initiated a multidisciplinary program designed to better understand and control BCWD through integrated research on host-pathogen and environmental interactions. Since 2005, rainbow trout have been bred for increased BCWD resistance using a laboratory challenge model with a genome-sequenced strain of Flavobacterium psychrophilum, CSF259-93. We demonstrate that post-challenge survival, an indicator of resistance, is a moderately heritable trait and we also observe improvement in survival following one generation of selective breeding. Pedigreed resistant, control and susceptible fish lines have been designed for mechanistic study and field performance evaluation. In these trout lines, we identified a positive phenotypic and genetic correlation between pre-challenge spleen size and post-challenge survival. Knowledge gaps exist regarding the molecular diversity of F. psychrophilum farm-isolates and the impact of this diversity on BCWD resistance. Utilizing comparative genomics, we identified loci with variability between F. psychrophilum strains and developed PCR assays for strain typing. Challenge experiments were performed to examine whether these bacterial strain differences affect disease resistance. Our results suggest that resistance is broad-based but that there is some interaction between host and pathogen genotype. On-farm trials are planned to evaluate progress in our genetic improvement program.