Efficacy of a recombinant Intimin,EspB and Shiga toxin 2B vaccine in calves experimentally challenged with Escherichia coli O157:H7 |
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| Affiliation: | 1. Instituto de Patobiología, Centro de Investigación en Ciencias Veterinarias y Agronómicas, Instituto Nacional de Tecnología Agropecuaria (INTA), Hurlingham, Argentina;2. Laboratorio de Fisiopatogenia, Departamento de Fisiología, Instituto de Fisiología y Biofísica Bernardo Houssay (IFIBIO Houssay-CONICET), Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina;3. Laboratorio de Patogénesis e Inmunología de Procesos Infecciosos, Instituto de Medicina Experimental, (IMEX), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Academia Nacional de Medicina, Buenos Aires, Argentina;4. Friedrich-Loeffler-Institut/Federal Research Institute for Animal Health, Institute of Molecular Pathogenesis, Jena, Germany;5. Instituto de Biotecnología, Centro de Investigación en Ciencias Veterinarias y Agronómicas, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina;1. Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, United States;2. Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, United States;3. Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL 32611, United States;4. North Florida Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Marianna, FL 32446, United States;5. Food Science and Human Nutrition Department, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, United States;1. Laboratory of Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium;2. Department of Animal Production, Faculty of Bioscience Engineering, Ghent University, Coupure Links 654, 9000 Gent, Belgium;3. Friedrich-Loeffler-Institut, Institute of Molecular Pathogenesis, Naumburger Str. 96a, 07743 Jena, Germany;1. Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran;2. Department of Pathobiology, Faculty of Veterinary Medicine, Garmsar Branch, Islamic Azad University, Garmsar, Iran;1. Imam Hossein University, Faculty of Science, Department of Biology, Tehran, Iran;2. Baqiyatallah University of Medical Sciences, Molecular Biology Research Center, Tehran, Iran;1. Department of Plant Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, Iran;2. Applied Microbiology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran;3. Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran |
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| Abstract: | Escherichia coli O157:H7 is a zoonotic pathogen of global importance and the serotype of Shiga toxin-producing E. coli (STEC) most frequently associated with Hemolytic Uremic Syndrome (HUS) in humans. The main STEC reservoir is cattle. Vaccination of calves with the carboxy-terminal fraction of Intimin γ (IntC280) and EspB can reduce E. coli O157:H7 fecal shedding after experimental challenge. Shiga toxin (Stx) exerts local immunosuppressive effects in the bovine intestine and Stx2B fused to Brucella lumazine synthase (BLS-Stx2B) induces Stx2-neutralizing antibodies. To determine if an immune response against Stx could improve a vaccine’s effect on fecal shedding, groups of calves were immunized with EspB + IntC280, with EspB + IntC280 + BLS-Stx2B, or kept as controls. At 24 days post vaccination calves were challenged with E. coli O157:H7. Shedding of E. coli O157:H7 was assessed in recto-anal mucosal swabs by direct plating and enrichment followed by immunomagnetic separation and multiplex PCR. Calves were euthanized 15 days after the challenge and intestinal segments were obtained to assess mucosal antibodies. Vaccination induced a significant increase of IntC280 and EspB specific antibodies in serum and intestinal mucosa in both vaccinated groups. Antibodies against Stx2B were detected in serum and intestinal mucosa of animals vaccinated with 3 antigens. Sera and intestinal homogenates were able to neutralize Stx2 verocytotoxicity compared to the control and the 2-antigens vaccinated group. Both vaccines reduced E. coli O157:H7 shedding compared to the control group. The addition of Stx2B to the vaccine formulation did not result in a superior level of protection compared to the one conferred by IntC280 and EspB alone. It remains to be determined if the inclusion of Stx2B in the vaccine alters E. coli O157:H7 shedding patterns in the long term and after recurrent low dose exposure as occurring in cattle herds. |
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| Keywords: | STEC EHEC O157:H7 Vaccine Antigens Protection |
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