Location: Cool and Cold Water Aquaculture Research
Project Number: 8082-10600-003-000-D
Project Type: In-House Appropriated
Start Date: Dec 9, 2024
End Date: Dec 8, 2029
Objective:
Objective 1: On-farm integration of genetic lines and biomarkers to develop strategies that reduce losses to disease. This objective has several related Subobjectives that utilize the defined disease-resistant and susceptible genetic lines developed over the last four consecutive project plans (20 years).
Sub-objective 1.A On-farm, production scale evaluation of YC2025 columnaris/BCWD double resistant line.
Sub-objective 1.B Discovery and laboratory validation of potential diagnostic biomarkers.
Sub-objective 1.C Development of biomarker reference intervals from juvenile through grow out.
Sub-objective 1.D Evaluate the effects of chronic high-temperature exposure on host disease resistance.
Objective 2: Identify host-pathogen interactions that can be exploited to improve fish health.
Sub-objective 2.A Identify pathogen genetic variation and impact on host resistance.
Sub-objective 2.B Evaluation of genetic resistance in the TLUM population against F. psychrophilum strain variants.
Objective 3: Develop vaccines and vaccination strategies that increase efficacy and duration of protection against disease.
Sub-objective 3.A Identify protective antigens in W. tructae and determine whether humoral immunity is involved in protection against this emerging pathogen.
Sub-objective 3.B Develop tools for the genetic manipulation of W. tructae.
Sub-objective 3.C Define antigenic variation in F. columnare for improved strain tracking and to inform vaccine development.
Objective 4: Identify and characterize microbiome membership and composition in production systems that can be modified to improve fish health.
Sub-objective 4.A Compare the influence of farm vs laboratory environment on gut bacterial microbiota during a field trial using defined genetic lines of rainbow trout.
Sub-objective 4.B Identify key Archaea and eukaryote microbiota members that are different in juvenile and adult resistant and susceptible trout.
Sub-objective 4.C Isolate commensal bacteria that are more abundant in resistant fish and characterize their interactions in vitro with defined pathogens to determine if this is a mechanism of resistance.
Approach:
Rainbow trout are a valuable finfish farmed in the U.S., with losses from infectious diseases being an important factor limiting production. The goals of this multidisciplinary project are to 1) evaluate selectively bred rainbow trout lines having multi-pathogen resistance under field conditions and determine immunological mechanisms of pathogen resistance, 2) develop biomarkers for measuring commercially relevant traits, 3) develop novel vaccines and application approaches that increase the duration of immunity, and 4) define and manipulate the microbiome of the rainbow trout thereby reducing pathogen susceptibility. Our approach incorporates a comprehensive strategy to solve fish health problems by combining selective breeding, quantitative genetics, immunology, and functional genomics of pathogenic bacteria. This research builds on our previous studies in which we developed and released to the industry a BCWD-resistant line (designated ARS-Fp-R) that has been extensively characterized and for which we have made progress in uncovering the mechanisms of disease resistance. In the first objective, we evaluate a BCWD/Columnaris double-resistant line in a field trial and directly evaluate the effect of chronic high-temperature exposure on host-pathogen resistance. We also develop biomarkers to aid the evaluation of fish health status. For the second objective, we characterize novel virulence factors and the potential for evasion of genetic resistance. For the third objective, we evaluate new vaccine candidates against Weissella tructae and Flavobacterium columnare and develop methods to extend vaccine protection. In the final objective, we utilize metagenomics to define the on-farm fish microbiome and its influence on the immune response. Results from this research will improve animal well-being, reduce antibiotic use, and increase trout farmer production efficiency and profitability.