** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** CLOSTRIDIUM PERFRINGENS-INDUCED AND COCCIDIOSIS-PREDISPOSED NECROTIC ENTERITIS (NE) HAS REEMERGED AS A PREVALENT POULTRY DISEASE WORLDWIDE BECAUSE OF RESTRICTING PROPHYLACTIC ANTIMICROBIAL PRACTICE. IT IS ESTIMATED THAT NE COSTS $6 BILLION PER YEAR WORLDWIDE. FEW AFFORDABLE ANTIMICROBIAL ALTERNATIVES ARE AVAILABLE TO PREVENT NE. OUR LONG-TERM GOAL IS TO CONTRIBUTE TOWARD THE DEVELOPMENT OF MECHANISM-BASED INTERVENTIONS TO MITIGATING NE IN CHICKENS. THE OVERALL OBJECTIVE IS TO DEVELOP ANTI-C. PERFRINGENS VACCINES AND BILE ACID REGIMENTS TO PREVENT NE. OUR CENTRAL HYPOTHESIS IS THAT NE WILL BE ATTENUATED THROUGH INHIBITING C. PERFRINGENS VIRULENCE BY HOST IMMUNE RESPONSE TO VACCINES OR BY SPECIFIC MICROBE-METABOLIZED BILE ACIDS. WE FORMULATE THIS HYPOTHESIS BASED ON OUR FINDINGS AND CURRENT STATE OF KNOWLEDGE THAT C. PERFRINGENS SPORULATION VACCINE OR DIETARY DEOXYCHOLIC ACID (DCA) EFFECTIVELY REDUCED CHICKEN NE. PROTEOMICS, IMMUNOINFORMATICS, AND ELISA ASSAYS IDENTIFIED LEAD PEPTIDES FOR DEVELOPMENT OF MULTIEPITOPE FUSION ANTIGEN (MEFA) VACCINES AGAINST C. PERFRINGENS VIRULENCE. DCA, ISOALLOLITHOCHOLIC ACID OR MICROBE-METABOLIZED CHENODEOXYCHOLIC ACID REDUCED C. PERFRINGENS GROWTH AND VIRULENCE. BASED ON THESE FINDINGS, WE PLAN TO ATTAIN THE OVERALL OBJECTIVE BY COMPLETING THE FOLLOWING SPECIFIC OBJECTIVES: OBJECTIVE 1: DEVELOP MULTIEPITOPE FUSION ANTIGENS VACCINES OF C. PERFRINGENS POLYVALENT FACTORS TO REDUCE CHICKEN NE. OBJECTIVE 2: DEVELOP MICROBE-METABOLIZED BILE ACID REGIMENTS TO REDUCE C. PERFRINGENS VIRULENCE AND CHICKEN NE. AT THE COMPLETION OF THE PROPOSED RESEARCH, WE WILL HAVE DEVELOPED MEFA VACCINES AND MICROBE-METABOLIZED BILE ACID REGIMENTS TO EFFECTIVELY REDUCE NE. ULTIMATELY, THE RESULTS OF THIS CONTINUUM OF RESEARCH WILL HAVE AN IMPORTANT POSITIVE IMPACT BY CONTRIBUTING MEANINGFULLY TOWARD THE DEVELOPMENT OF MECHANISM-BASED STRATEGIES TO PREVENT