** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE CONTINUING CIRCULATION OF MULTIPLE SALMONELLA SEROVARS IN POULTRY FLOCKS, ALONG WITH INCREASING REPORTS OF HUMAN SALMONELLOSIS, WARRANTS THE NECESSITY OF COMPLEMENTARY STRATEGIES AGAINST A BROAD RANGE OF SEROVARS. THE GOAL OF THIS APPLICATION IS TO EVALUATE THE SAFETY AND EFFICACY OF A LIVE PROBIOTIC BACILLUS SUBTILIS STRAIN IN REDUCING THE SALMONELLA LOAD IN BROILER BIRDS. THE PI HAS ENGINEERED B. SUBTILIS-FLIC TO SECRETE MONOVALENT AND BIVALENT NEUTRALIZING NANOBODIES (NBS) AGAINST A KEY VIRULENT FACTOR, FLAGELLIN C IN SALMONELLA. NBS FROM CAMELIDAE FEATURE SMALL SIZE, HIGH SOLUBILITY, PROTEASE RESISTANCE, AND HIGH THERMAL STABILITY COMPARED TO CONVENTIONAL ANTIBODIES. WHILE NATURAL B. SUBTILIS PROBIOTICS HAVE BEEN IDENTIFIED TO PROMOTE GUT HEALTH IN POULTRY, A MAJOR DISTINCTION OF THIS PROPOSAL IS TO RATIONALLY DESIGN B. SUBTILIS WITH TRAITS AGAINST VIRULENT FACTORS TO DIRECTLY INHIBIT SALMONELLA COLONIZATION AND LOADS IN BROILERS. THE PLATFORM TECHNOLOGY FROM THIS PROPOSAL WILL ULTIMATELY OPEN OPPORTUNITIES FOR TARGETING OTHER ENTERIC PATHOGENS IN POULTRY AND LIVESTOCK, THEREBY PROMOTING THE WELL-BEING OF AGRICULTURAL ANIMALS, AND ENSURING A SAFE AND ABUNDANT FOOD SUPPLY.