FDA HAS BANNED MEDICALLY IMPORTANT ANTIBIOTICS FOR USE IN U.S. LIVESTOCK PRODUCTION SINCE 2017. FEW EFFECTIVE ANTIBIOTIC ALTERNATIVES EXIST, ACCENTUATING THE NEED FOR NOVEL STRATEGIES. MODULATION OF ENDOGENOUS HOST DEFENSE PEPTIDES (HDP), AN EARLY-ACTING COMPONENT OF THE IMMUNE SYSTEM, HAS EMERGED AS A PROMISING ANTIBIOTIC-ALTERNATIVE APPROACH. WE HAVE FOUND TWO DIFFERENT CLASSES OF EPIGENETIC MODIFIERS, NAMELY HISTONE DEACETYLASE INHIBITORS (HDACI) AND HISTONE METHYLTRANSFERASE INHIBITORS (HMTI), THAT SYNERGIZE DRAMATICALLY IN AUGMENTING CHICKEN HDP GENE EXPRESSION. THE OVERALL GOAL OF THIS PROJECT IS TO INVESTIGATE THE SYNERGISTIC MECHANISM BETWEEN EPIGENETIC MODIFIERS IN HDP INDUCTION. OUR HYPOTHESIS IS THAT HMTI AND HDACI ENHANCE HDP GENE TRANSCRIPTION BY WORKING COOPERATIVELY TO INCREASE THE ACCESSIBILITY OF HDP GENE PROMOTERS TO TRANSCRIPTIONAL MACHINERY. TWO SPECIFIC OBJECTIVES ARE PROPOSED TO 1) CONFIRM THE SYNERGY IN HDP INDUCTION BETWEEN HDACI AND HMTI IN DIFFERENT CHICKEN CELL TYPES, AND 2) EVALUATE THE COOPERATIVE ACCESSIBILITY OF THE HDP GENE PROMOTERS IN RESPONSE TO HDACI AND HMTI THROUGH EPIGENETIC TECHNIQUES INCLUDING CHROMATIN IMMUNOPRECIPITATION (CHIP) AND RNA INTERFERENCE. WE EXPECT TO IDENTIFY SEVERAL COMBINATIONS OF EPIGENETIC COMPOUNDS SHOWING A STRONG SYNERGY IN HDP INDUCTION, WITH NO NEGATIVE IMPACT ON INTESTINAL BARRIER FUNCTION OR INFLAMMATION. THESE COMPOUNDS ARE EXPECTED TO WORK BY ENHANCING THE ACCESSIBILITY OF THE HDP GENE PROMOTERS BY INCREASING HISTONE ACETYLATION WHILE SUPPRESSING HISTONE METHYLATION. THE OUTCOMES OF THE RESEARCH WILL FACILITATE THE DEVELOPMENT OF EPIGENETIC MODIFIERS AS THE FIRST-OF-ITS-KIND CLASS OF ALTERNATIVES TO ANTIBIOTICS FOR DISEASE CONTROL AND PREVENTION IN LIVESTOCK. IMPORTANTLY, THE PROJECT WILL SUPPORT AN UP-AND-COMING SCIENTIST AS SHE PURSUES AN ACADEMIC CAREER IN ANIMAL IMMUNOLOGY.