SBIR-STTR Award

Gram-negative bacterium Francisella oriental is the etiologic agent of piscine francisellosis infects various freshwater and marine fish species worldwide. In the USA the disease causes high mortalities in tilapia and other warm-water fishes including ornamental cichlids largemouth bass hybrid striped bass French grunts and Caesar grunts. Lack of sensitive diagnostic tests approved treatments and vaccines in the U.S. aquaculture industry have resulted in over 90% mortalities in some cases. Economic losses from francisellosis result directly from fish mortalities and through delayed production and growth added labor costs and potential treatment expenditures over time. While antibiotics are still used to treat bacterial diseases treatments often fail for lack of ingestion by anorectic fish. On the other hand the release of antibiotics into natural habitats poses a potential environmental threat. Thus disease prevention through vaccination is preferred over antibiotics treatment. Costs and the efficacy of available vaccines against intracellular pathogens have been challenging for the aquaculture industry. With tools and techniques developed by PhycoVax and the expertise of a collaborating partner at the University of California Davis this project proposes investigating the potential use of algae- based subunit vaccines to protect Nile tilapia against piscine francisellosis. The efficacy of a feed-based vaccine will be investigated by feeding whole diatom cells expressing antigen- adjuvant fusion protein to na¯ve tilapia fingerlings. A successful development of algae-based oral aquaculture vaccines will open the door to rapid generation of novel cost-effective fish vaccines resulting in improved aquaculture health and productivity of the U.S. aquaculture industry.