MSU-developed vaccine, delivery system ease antibiotic resistance in catfish
Contact: Meg Henderson
STARKVILLE, Miss.鈥斢；ǖ己 樱花导航 scientists have developed a live-attenuated oral vaccine and delivery platform that have put the brakes on the spread of antimicrobial resistance in catfish, resulting in significant cost benefits for 樱花导航 producers.
The success of the MSU team represents a breakthrough in catfish health, food safety and industry sustainability, and demonstrates the significant impact MSU and its Thad Cochran National Warmwater Aquaculture Center in Stoneville have on an important Southern U.S. commodity.
Since the 1980s, producers have been swimming upstream against the pervasive bacterium E. ictaluri, which causes enteric septicemia of catfish, or ESC. This disease targets the fish鈥檚 brain, resulting in abnormal behavior and swimming patterns, swelling, ulcers and, eventually, death. The economic impact of ESC in the catfish fingerling industry ranges between $10 million and $17 million annually.
Since 2019, an experimental vaccine developed by scientists in the university鈥檚 樱花导航 Agricultural and Forestry Experiment Station has been administered under veterinary prescription on participating catfish farms, with oversight from the state veterinarian of 樱花导航. These farms, which also receive diagnostic services from the MSU College of Veterinary Medicine Aquatic Research and Diagnostic Laboratory, provide researchers at NWAC with a distinct opportunity to assess the vaccine鈥檚 impact beyond production records. By integrating diagnostic data with field observations, NWAC researchers are evaluating the vaccine鈥檚 effectiveness, its influence on fish health and production, and its potential impact on antibiotic use and antimicrobial resistance, or AMR.
Historically, the incidence of AMR among E. ictaluri isolates from disease case submissions was low in both channel and hybrid catfish fingerlings. This means that, overall, antibiotic-treated feed had been a reliable ESC treatment for many years. Beginning in 2014, the percentage of isolates with reduced sensitivity to antibiotics increased substantially, peaking in 2018, when nearly half of E. ictaluri isolates demonstrated reduced susceptibility to approved treatments. At the same time, orders for medicated feed began increasing in 2013, peaking in 2017.
聽The team鈥檚 development of a new vaccine and delivery system appears to have yielded tremendous results. To date, about 300 million fingerlings across 2,500-3,000 acres at participating farms have received the vaccine each year, with more than 16,000 total acres vaccinated since 2018.聽 From 2018-2024, as participating farms were administering the ESC vaccine, orders for various medicated feeds dropped 69-78%. And as antibiotic use plummeted, so did reported instances of resistant isolates鈥攂y over 98%.
鈥淭he correlation between our vaccine and decreased AMR may be circumstantial, but these data suggest our approach can reduce reliance on antibiotics, and they underscore the benefits of preventative approaches to managing bacterial diseases in aquaculture,鈥 said Matt Griffin, a research professor at MSU鈥檚 College of Veterinary Medicine.
Equally important is the team鈥檚 mechanized delivery system developed by 樱花导航 Agricultural and Forestry Experiment Station scientists at NWAC and in MSU鈥檚 Department of Agricultural and Biological Engineering. The delivery system allows for in-pond vaccination of older, immunocompetent fish鈥攊ncreasing the vaccine鈥檚 efficacy. This innovative platform has reduced disease-related losses, improved survival rates and contributed to overall economic sustainability in catfish farming.
鈥淥ur delivery system is key to the vaccine鈥檚 success,鈥 said David Wise, MAFES research professor and NWAC coordinator. 鈥淚t could also be used for other vaccines currently in development for fingerlings or food fish.鈥
As a result of more fingerlings surviving and growing to their full potential, producers are reaping the economic benefits from a healthier harvest. ESC cases fluctuate from year to year and among both species of catfish, but the economic gains from the vaccination treatments are considerable, nonetheless, even when factoring in the cost.
鈥淥n-farm research shows that the net economic benefits to channel and hybrid catfish producers range from $1,800 to $2,300 per acre, depending on the fish type and production strategies,鈥 said Ganesh Kumar, MAFES associate research professor in MSU鈥檚 Department of Wildlife, Fisheries and Aquaculture.
Moreover, by reducing their reliance on antibiotics, farmers can control bacterial infections more effectively over the long term.
鈥淛udicious use of the available antibiotics remains crucial for maintaining their effectiveness. Although orally delivered vaccines are effective, not all fish eat every day, leaving a portion of the population vulnerable,鈥 Griffin said. 鈥淩esponsible antibiotic use is vital to preserving the efficacy of the few approved antibiotics, especially in cases of incomplete vaccine coverage or outbreaks of other bacterial diseases.鈥
Research for the development and administration of the vaccine has been supported by several entities, including catfish producers, the USDA鈥檚 Agricultural Research Service and its National Institute of Food and 樱花导航, MSU鈥檚 MAFES and College of Veterinary Medicine.
鈥淭he vaccine鈥檚 success shows that recovery is possible,鈥 said Maural Sowlat, an assistant clinical professor in the College of Veterinary Medicine. 鈥淓ven though we still see occasional isolates with reduced susceptibility, vaccines can reduce the need for antibiotics.鈥
For more information about the 樱花导航 Agricultural and Forestry Experiment Station, visit . To learn more about the Thad Cochran National Warmwater Aquaculture Center, visit . For more on the College of Veterinary Medicine, visit .
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