** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THIS PROJECT AIMS TO DEVELOP A LIVE-ATTENUATED DIVALENT VACCINE TARGETING CAMPYLOBACTER JEJUNI AND CAMPYLOBACTER COLI, THE LEADING CAUSES OF FOODBORNE ILLNESSES IN THE U.S., PRIMARILY TRANSMITTED THROUGH CONTAMINATED POULTRY MEAT. GIVEN THE SIGNIFICANT ROLE OF POULTRY AS A RESERVOIR FOR CAMPYLOBACTER, EFFECTIVE PREHARVEST CONTROL IS CRUCIAL FOR REDUCING THE RISK OF HUMAN CAMPYLOBACTERIOSIS. DESPITE THE EFFICACY OF VACCINATION IN CONTROLLING FOODBORNE PATHOGENS IN LIVESTOCK, NO VACCINES ARE CURRENTLY AVAILABLE FOR CAMPYLOBACTER. BUILDING ON OUR PREVIOUS RESEARCH THAT SUCCESSFULLY REDUCED C. JEJUNI LEVELS IN CHICKEN INTESTINES, THIS PROJECT AIMS TO CONSTRUCT AN ORAL DIVALENT VACCINE FOR BROILERS TO DECREASE CAMPYLOBACTER CONTAMINATION ON CHICKEN MEAT. THE RESEARCH IS FOCUSED ON ACHIEVING THREE KEY GOALS. FIRSTLY, IT AIMS TO CONSTRUCT A DIVALENT VACCINE TARGETING BOTH C. JEJUNI AND C. COLI, LEVERAGING OUR PREVIOUSLY DEVELOPED EFFECTIVE LIVE-ATTENUATED C. JEJUNI VACCINE. SECONDLY, WE WILL ESTABLISH ORAL ADMINISTRATION OF THE VACCINE VIA DRINKING WATER, A COMMON METHOD FOR MASS VACCINATION IN POULTRY. FINALLY, WE WILL ASSESS THE VACCINATION EFFICACY IN REDUCING CAMPYLOBACTER CONTAMINATION OF CHICKEN CARCASSES. IMPORTANTLY, THE VACCINE STRAINS ARE DESIGNED TO ENSURE THAT THEY CANNOT SURVIVE ON CARCASSES AT PROCESSING. THE EXPECTED OUTCOME IS A DIVALENT VACCINE THAT SIGNIFICANTLY REDUCES CAMPYLOBACTER IN CHICKENS. THIS PROJECT ALIGNS WITH THE PRIORITY AREA OF FOOD SAFETY AND DEFENSE, ULTIMATELY AIMING TO IMPROVE FOOD SAFETY THROUGH EFFECTIVE CAMPYLOBACTER VACCINATION STRATEGIES.