Harrison

Identification of Columnaris Disease Vaccine Candidates for Catfish and Other Aquaculture Fish Species in the Southern Region

1Courtney E. Harrison, 2Benjamin R. LaFrentz, 3Matt J. Griffin, 4Thomas P. Loch, 5Esteban Soto, and 1Timothy J. Bruce

1School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, Auburn, AL; 2USDA-ARS Aquatic Animal Health Research Unit, Auburn, AL; 3Thad Cochran National Warmwater Aquaculture Center, Mississippi State University, Stoneville, MS; 4Aquatic Animal Health Laboratory, Michigan State University, East Lansing, MI; 5Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA

ABSTRACT

Columnaris disease, caused by the Gram-negative and yellow-pigmented bacterium Flavobacterium columnare, is a leading pathogen in global aquaculture. In the southeastern United States, columnaris disease is responsible for significant losses in the catfish industry. The development of an efficacious vaccine for the prevention and control of columnaris disease has been restricted partially due to a lack of understanding of the broad genetic diversity of F. columnare. Because of phylogenetic and biochemical similarities, yet distinct genetic differences, strains of columnaris-causing bacteria (CCB) were categorized into genomovars. Next, established genetic groups (GG) of CCB revealed biological associations between GGs and host species. As of 2022, CCB now represents four distinct species: F. columnare, F. covae, F. davisii, and F. oreochromis. There is currently a licensed, attenuated vaccine for columnaris disease in channel catfish and largemouth bass; however, inconsistent vaccine efficacy has been reported under production settings. One possible reason for the lack of efficacy is the sub-optimal host-pathogen dynamics. With the newfound knowledge of CCB-causing species diversity and affinity for different host fish species, vaccine development has been re-initiated. This new project aims to identify and develop CCB strains associated with channel catfish and other aquaculture fish species to create a live-attenuated vaccine for columnaris disease. To achieve viable vaccine candidates, this project aims to confirm and characterize strain attenuation. Safety testing and delivery optimization (immersion or oral administration routes) will be performed on the most promising candidates. Finally, the attenuated vaccine will be tested in channel catfish fingerlings under experimental pond conditions in Mississippi. This project aims to produce a viable vaccine candidate for the protection of catfish and other important aquaculture fish species in the Southern region against columnaris disease.

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