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Courtesy of NAA:

Catfish are an economically important agricultural commodity for several southern U.S. states, with total sales of $360 million in 2018. However, the emerging pathogen, E. piscicida bacterium, is causing infections in catfish and other farm-raised fish. The increase in E. piscicida infections is leading to increases in antibiotic use and severe economic losses in aquaculture.

The Foundation for Food & Agriculture Research (FFAR) is awarding a $645,390 Seeding Solutions grant to Mississippi State University (MSU) to develop effective vaccines against E. piscicida with the University of California, Davis (UC Davis). The researchers are focusing on vaccines for two economically important cultured fish: hybrid catfish and rainbow trout. MSU and UC Davis provided matching funds for a total $1,305,838 investment.

Several antimicrobials are effective in treating E. piscicida infections. However, international, federal and state regulations limit antibiotic use in aquaculture. Additionally, the cost of medicated feed is high and public preference is for antibiotic-free animal products, making the use of antimicrobials a difficult choice for producers. There are no commercial vaccines available to prevent E. piscicida. This research aims to develop a vaccine to mitigate E. piscicida in farmed-fish, thereby reducing the number of infected fish and the need for antibiotics.

“With no viable alternatives for safeguarding their fish from E. piscicida, aquaculturists have seen major losses due to this pathogen in recent years,” said Dr. Saharah Moon Chapotin, FFAR executive director. “FFAR is proud to support this research that is developing effective vaccines to protect fish and enhance farmer profitability.”

Dr. Matt Griffin, research professor at MSU’s Thad Cochran National Warmwater Aquaculture Center, is partnering with Dr. Esteban Soto at UC Davis to investigate three different approaches to vaccine development: live-attenuated vaccines, whole killed vaccines and recombinant protein vaccines. The research team is also evaluating multiple routes of administration: injection, immersion and oral. MSU is conducting research on catfish, while UC Davis is evaluating these strategies in rainbow trout, affording researchers the opportunity to assess multiple approaches simultaneously.

“The vaccine strategies we’re exploring have been successfully applied against multiple fish pathogens in various fish species, including the closely related Edwardsiella ictaluri in channel and hybrid catfish,” Griffin said. “This project is ambitious but working collaboratively with Dr. Soto’s lab allows us to investigate multiple approaches concurrently. We believe this multi-faceted approach has a high probability of success and should expedite identification of a viable vaccine candidate as well as method of delivery.”

Griffin and Soto have previously made significant advancements in the understanding of E. piscicida in the context of fish health, including being part of the team that first identified E. piscicida bacteria in the southeastern U.S. as an emergent pathogen in catfish aquaculture. This research builds upon these findings.