CHANNEL CATFISH IS AN IMPORTANT AQUACULTURAL SPECIES ON A GLOBAL SCALE. HERE IN THE UNITED STATES, CATFISH FARMING IS A LARGE INDUSTRY THAT PRODUCED $371 MILLION IN SALES IN 2020 (USDA). EACH YEAR, FARMERS SUFFER SIGNIFICANT CROP LOSSES DUE TO INFECTIOUS DISEASES. MAJOR CATFISH PATHOGENS INCLUDE THE BACTERIAL PATHOGENS EDWARDSIELLA ICTALURI, AND FLAVOBACTERIUM COLUMNARE. IN ADDITION, CHANNEL CATFISH VIRUS (CCV) INFECTS YOUNG FISH, LESS THAN ONE YEAR-OLD. TARGETED IMMUNE THERAPY THROUGH VACCINES COULD PREVENT CROP LOSS BY BOOSTING THE IMMUNE RESPONSE TO VARIOUS PATHOGENS. SUCH TECHNIQUES HAVE BEEN USED IN MAMMALS AND TO A LESSER EXTENT IN FISH.TOLL-LIKE RECEPTORS (TLRS) ARE IMMUNE RECEPTORS EXPRESSED ON THE CELL SURFACE OR IN COMPARTMENTS WITHIN THE CELL. THESE RECEPTORS RECOGNIZE SPECIFIC STRUCTURES ON MICROBES. EACH DIFFERENT TLR TYPE RECOGNIZES A DIFFERENT MICROBIAL STRUCTURE AND THESE STRUCTURES ARE TERMED MICROBE-ASSOCIATED MOLECULAR PATTERNS (MAMPS). THE RECOGNITION TRIGGERS AN IMMUNE RESPONSE TO THE MICROBES THAT ARE EXPRESSING THAT MAMP. IN ADDITION, SOME MAMMALIAN TLR MEMBERS CAN FORM DIFFERENT COMBINATIONS AND RECOGNIZE OTHER MAMPS. IN CATFISH, 20 DIFFERENT TLR GENES HAVE BEEN IDENTIFIED, IN CONTRAST TO ONLY 10 IN HUMANS (QUINIOU ET. AL 2013). THIS LEAD TO THE HYPOTHESIS THAT CATFISH RECOGNIZE UNIQUE PATHOGENS THAT ARE FOUND IN THEIR AQUATIC ENVIRONMENT. THE GOAL OF THIS PROJECT IS TO STUDY CATFISH TLRS, AND DETERMINE THEIR RESPECTIVE LIGANDS OR MAMPS, AND ALSO INVESTIGATE IF DIFFERENT CATFISH TLRS COMBINE IN ORDER TO RECOGNIZE DIFFERENT LIGANDS. THE RESULTS OF THESE STUDIES COULD HELP IMPROVE VACCINES BY THE INCORPORATION OF DIFFERENT TLR LIGANDS AS IMMUNE ENHANCING AGENTS, WHICH IN TURN WILL HAVE A POSITIVE IMPACT ON THE AQUACULTURE INDUSTRY. IN ADDITION, THESE STUDIES WILL ENHANCE THE UNDERSTANDING OF FISH IMMUNE FUNCTIONS.