THIS PROJECT WORKS ON AVIAN COLIBACILLOSIS, A MAJOR AND COSTLY INFECTIOUS DISEASE WITH MAJOR DETRIMENTAL IMPACT ON ALL FACETS OF THE POULTRY INDUSTRY WORLDWIDE. COLIBACILLOSIS IS CONSIDERED TO BE THE MOST IMPORTANT INFECTIOUS DISEASE OF POULTRY CAUSING SEVERE ECONOMIC LOSSES FROM MORTALITY, MORBIDITY, LOSS OF PRODUCTION AND CONDEMNATIONS AT PROCESSING THUS PUTTING AT RISK ONE OF THE WORLD'S CHEAPEST SOURCES OF HIGH QUALITY PROTEIN. AVIAN COLIBACILLOSIS IS CAUSED BY AVIAN PATHOGENIC ESCHERICHIA COLI (APEC). GIVEN THE WIDESPREAD INEFFECTIVENESS OF MANAGEMENT APPROACHES IN CONTROLLING APEC AS WELL AS APEC'S GROWING ANTIMICROBIAL RESISTANCE, VACCINE-BASED CONTROL APPROACHES HAVE BEEN EXTENSIVELY PURSUED IN RECENT YEARS. HOWEVER, DUE TO THE SIGNIFICANT STRAIN VARIATIONS IN APEC, PREVIOUS VACCINE-BASED APPROACHES HAVE PROVIDED ONLY LIMITED BENEFIT AS VACCINES TEND TO BE EFFECTIVE ONLY AGAINST CERTAIN SPECIFIC APEC SEROTYPES. THUS, DEVELOPMENT OF VACCINES AGAINST A WIDE RANGE OF APECIS HIGHLY DESIRABLE. ONE SUCH VACCINE TARGET IS ENTEROBACTIN (ENT), A FUNCTIONALLY CONSERVED FERRIC IRON-BINDING MOLECULE (ALSO NAMED AS 'SIDEROPHORE') IN ALL APEC; THE ENT IS A COMMON AND SIGNIFICANT MEANS USED BY DIVERSE E. COLI FOR OBTAINING IRON, A NECESSARY NUTRIENT, DURING INFECTION. RECENT STUDIES HAVE SHOWN THAT ENT-BINDING PROTEINS (INCLUDING ANTIBODIES) CAN CONTROL INFECTION BY STARVING PATHOGENS OF IRON. RECENTLY, WE HAVE SUCCESSFULLY PRODUCED ENT CONJUGATE VACCINES THAT ELICIT ENT-SPECIFIC ANTIBODIES, LEADING US TO HYPOTHESIZE THAT THE ENT CONJUGATE VACCINE CAN PREVENT AVIAN COLIBACILLOSIS CAUSED BY VARIOUS APEC. HERE, WE WILL EVALUATE THE EFFICACY OF ENT CONJUGATE VACCINE TO PROVIDE CROSS PROTECTION TO HETEROLOGOUS APEC USING DISTINCT APPROACHES. COMPLETION OF THIS PROJECT WOULD PROVIDE CRITICAL INFORMATION FOR THE DEVELOPMENT OF NOVEL, BROAD-SPECTRUM, LOW-COST, PRACTICAL AND EFFICACIOUS VACCINES AGAINST AVIAN COLIBACILLOSIS.SPECIFICALLY, WE WILL PURSUE THE FOLLOWING THREE OBJECTIVES:EVALUATE THE IMMUNOGENICITY OF THE ENT CONJUGATE VACCINE AND ITS EFFICACY IN PROTECTING BROILERS FROM COLIBACILLOSIS.ASSESS THE ENT CONJUGATE VACCINE'S ABILITY TO PREVENT COLIBACILLOSIS IN LAYERS AND YOLK SAC INFECTIONS IN THEIR HATCHLINGS.DETERMINE THE EFFICACY OF PASSIVE IMMUNIZATION USING ENT-SPECIFIC EGG YOLK ANTIBODIES FOR PROTECTING CHICKENS FROM COLIBACILLOSIS.