CAMPYLOBACTER JEJUNI INFECTIONS IN HUMANS CONTINUE TO BE A MAJOR CAUSE OF BACTERIAL GASTROENTERITIS IN THE U.S. MOST CASES HAVE BEEN ASSOCIATED WITH POULTRY HANDLING, POULTRY PRODUCT CONSUMPTION OR CROSS-CONTAMINATION. WHEN C. JEJUNI COLONIZES THE CHICKEN GUT, THE CHICKENS SEEM TO BE UNABLE TO CLEAR THE INFECTION DURING THEIR PRODUCTION LIFESPAN. THIS PROPOSAL WILL INVESTIGATE THE COMPLEX MICROBIAL INTERACTIONS THAT OCCUR IN THE CHICKENWITH THE GOAL OF DESIGNING TARGETED INTERVENTIONS THAT MAKE THE CHICKEN AN UNFAVORABLE ENVIRONMENT FOR C. JEJUNI COLONIZATION. THE SPECIFIC OBJECTIVES ARE:1.- DETERMINE THE EFFECTS OF INTERVENTIONS TARGETING THE GUT MICROBIOME ON THE COLONIZATION DYNAMICS OF C. JEJUNI IN BROILER CHICKENS.2.- ESTIMATE THE IMPACT OF INTERVENTIONS TARGETING THE GUT MICROBIOME IN REDUCING THE LOAD OF C. JEJUNI ON BROILER CARCASSES USING A USER-FRIENDLY MATHEMATICAL MODELING APPROACH.FINDINGS FROM THIS PROJECT WILL SIGNIFICANTLY IMPROVE OUR UNDERSTANDING OFOF CAMPYLOBACTER IN THE CHICKEN ENVIRONMENT; THIS KNOWLEDGE WILL HELP IN THE DEVELOPMENT OF STRATEGIES THAT SHIFT THE BALANCE FROM A FAVORABLE TO A HOSTILE MICROENVIRONMENT FOR C. JEJUNI. THIS WILL RESULT IN THE IMPROVEMENT OF THE SAFETY OF CHICKEN MEAT.