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ARS Home » Northeast Area » Leetown, West Virginia » Cool and Cold Water Aquaculture Research » Research » Research Project #428108

Research Project: Integrated Research to Improve On-Farm Animal Health in Salmonid Aquaculture

Location: Cool and Cold Water Aquaculture Research

Project Number: 8082-32000-006-00-D
Project Type: In-House Appropriated

Start Date: Dec 9, 2014
End Date: Dec 8, 2019

Objective:
Objective 1: Define phenotypes and identify genetic markers to enhance selective breeding for disease resistance. Sub-objective 1.a. Selective breeding for improved CD resistance using the ARS-Fp-R line. Sub-objective 1.b. Evaluate approaches to exploit intra-family genetic variation for disease resistance to BCWD. Sub-objective 1.c. Fine-map the Omy19 BCWD QTL and determine mechanism of increased survival. Sub-objective 1.d. Evaluate survival, performance, environmental effects, and IHNV vaccination of ARS-Fp-R line in a 2015 large-scale field trial. Sub-objective 1.e. Evaluate ARS-Fp/Fc-R line in field trials. Sub-objective 1.f. Develop Fp and Fc isolate databases and elucidate genomic and virulence variation. Objective 2: Improve vaccine development through pathogen characterization. Sub-objective 2.a. Characterize expression of the Yr flagellar secretion phenotype during the infection process and characterize the role of flhDC in flagellar secretion regulation. Sub-objective 2.b. Identify flagellar regulatory elements and identify the flagellar secretion component(s) which antagonize virulence in Yr. Sub-objective 2.c. Evaluate strain TW32 as a live attenuated vaccine strain and as a novel carrier vaccine for en masse delivery of protein antigens to fish. Sub-objective 2.d. Delineate the molecular, structural and antigenic repertoire of the O-polysaccharides(O-PS) present in Fp and develop typing reagents. Objective 3: Genomic characterization of bacterial-host-environmental interactions leading to the disease state. Sub-objective 3.a. Metagenomic analysis of the aquaculture environment. Sub-objective 3.b. Determine the importance of Type III Secretion systems in mesophilic Aeromonads causing disease in rainbow trout.

Approach:
Rainbow trout are a valuable finfish farmed in the U.S. and worldwide. Loss of trout from infectious disease is an important factor limiting production efficiency. Three prevalent bacterial diseases of rainbow trout are bacterial cold water disease (BCWD), enteric redmouth disease (ERM), and recently emerging, columnaris disease (CD). The goals of this project are to 1) develop well-characterized germplasm that exhibits dual on-farm resistance to both BCWD and CD, 2) utilize pathogen genomics to aid vaccine development and selective breeding, and 3)characterize both the host and aquaculture microbiome(s) associated with pathogen outbreaks. Our approach incorporates a comprehensive and multidisciplinary strategy that combines selective breeding, quantitative genetics, immunophenotyping, and functional genomics of pathogenic bacteria. This research builds on our previous studies in which we developed and released to industry, a BCWD resistant line (ARS-Fp-R) that has been extensively immunophenotyped, and have made progress in uncovering the genetic basis of disease resistance. In the first objective, we initiate selective breeding to improve CD survival, evaluate on-farm performance of single and double pathogen resistant lines and identify strategies for improving selective breeding for disease resistance. In the second objective, we characterize virulence factor regulation, develop serotyping tools, and evaluate new vaccine strategies to prevent disease. In the third objective, we utilize metagenomics and functional-genetic analyses to define the microbiome, identify virulence factors, and elucidate the contribution of these factors to disease outbreaks. The overall impact of this research is improved animal well-being, reduced antibiotic use and increased production efficiency.