Live-Attenuated Vaccine Development and Immunopotentiation Strategies to Control Streptococcosis in U.S. Catfish Aquaculture

Streptococcosis caused by the emerging bacterial pathogen Streptococcus dysgalactiae presents a rapidly growing threat to the profitability and long-term viability of the U.S. catfish aquaculture industry. This bacterial disease primarily impacts channel catfish broodstock during spawning season, causing direct fish losses and poor hatch rates that drastically reduce economic returns and regional fingerling supply. Treatment options are limited, and application of antibiotics in broodstock is restricted by logistic and safety complications. This project will address these issues by delivering complementary tools for proactive disease prevention. Specifically, it will (1) develop live-attenuated S. dysgalactiae vaccine strains optimized for feed-based delivery and (2) evaluate immunostimulant feed additives for improved catfish health and resistance to S. dysgalactiae infection. These approaches were designed with industry input and can be readily integrated into existing catfish farming practices to provide both pathogen-specific protection and enhanced immune readiness. By delivering practical, producer-focused solutions for fish health management, this project will strengthen domestic aquaculture production, support rural economies, and contribute to a more resilient U. S. food system.