title: Immune Response in Calves Vaccinated with Type Three Secretion System Antigens and Shiga Toxin 2B Subunit of Escherichia coli O157:H7.
abstract: Ruminants are the primary reservoir of Shiga-toxin producing Escherichia coli (STEC) O157:H7 and the main source of infection for humans. The aim of this study was to assess the immunogenic properties of a candidate vaccine consisting on the recombinant proteins of E. coli O157:H7 IntiminC280, the carboxy-terminal fraction of Intimin γ, EspB and the fusion protein between the B subunit of Stx2 and Brucella Lumazine Synthase (BLS)(BLS-Stx2B), in Holstein Fresian calves.To accomplish this goal we vaccinated calves with two doses of different vaccine formulations: 2 antigens (IntiminC280, EspB), 3 antigens (IntiminC280, EspB, BLS-Stx2B), BLS-Stx2B alone and a control non-vaccinated group. All antigens were expressed as recombinant proteins in E. coli. Specific IgG titres increased in vaccinated calves and the inclusion of BLS-Stx2B in the formulation seems to have a stimulatory effect on the humoral response to IntiminC280 and EspB after the booster. The neutralizing activity of antibodies against these two antigens was assessed in Red Blood Cell lysis assays and adherence to Hep-2 cells as a correlate of T3SS activity. Both sera from animals vaccinated with 2 or 3 antigens inhibited both virulence properties. Serological response to Stx2 was observed in animals vaccinated only with BLS-Stx2B and with 3 antigens and neutralization of Stx2 cytotoxicity was also observed in both groups. In conclusion, immunization of calves with BLS-Stx2B, IntiminC280 and EspB elicited a potent humoral response able to neutralize Shiga toxin 2 cytotoxity and the T3SS virulence properties in vitro. These results suggest that this formulation is a good candidate vaccine to reduce STEC shedding in cattle and needs to be further assessed in vivo.
authors.affiliation: Instituto de Patobiología, Centro de Investigación en Ciencias Veterinarias y Agronómicas, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina.
authors.forename: Luisina
authors.initials: L
authors.lastname: Martorelli
authors.affiliation: Instituto de Patobiología, Centro de Investigación en Ciencias Veterinarias y Agronómicas, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina.
authors.forename: Sergio
authors.initials: S
authors.lastname: Garbaccio
authors.affiliation: Instituto de Patobiología, Centro de Investigación en Ciencias Veterinarias y Agronómicas, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Vilte
authors.affiliation: Laboratorio de Fisiopatogenia, Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Adriana A
authors.initials: AA
authors.lastname: Albanese
authors.affiliation: 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.
authors.forename: María P
authors.initials: MP
authors.lastname: Mejías
authors.affiliation: 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.
authors.forename: Marina S
authors.initials: MS
authors.lastname: Palermo
authors.affiliation: Instituto de Patobiología, Centro de Investigación en Ciencias Veterinarias y Agronómicas, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina.
authors.forename: Elsa C
authors.initials: EC
authors.lastname: Mercado
authors.affiliation: Laboratorio de Fisiopatogenia, Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Cristina E
authors.initials: CE
authors.lastname: Ibarra
authors.affiliation: Instituto de Biotecnología, Centro de Investigación en Ciencias Veterinarias y Agronómicas, Instituto Nacional de Tecnología Agropecuaria, Hurlingham, Argentina.
authors.forename: Angel A
authors.initials: AA
authors.lastname: Cataldi
mesh_terms: D018829:Adhesins, Bacterial / Q000378:metabolism; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D057138:Bacterial Shedding; D002417:Cattle / Q000276:immunology*; D002418:Cattle Diseases / Q000276:immunology* / Q000382:microbiology; D002448:Cell Adhesion; D002522:Chlorocebus aethiops; D004912:Erythrocytes / Q000382:microbiology; D004927:Escherichia coli Infections / Q000276:immunology / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000378:metabolism; D022361:Escherichia coli Vaccines / Q000276:immunology*; D056724:Immunity, Humoral; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D011994:Recombinant Proteins / Q000276:immunology; D022641:Shiga Toxin 2 / Q000276:immunology*; D000069296:Type III Secretion Systems; D014709:Vero Cells; D014774:Virulence
chemical_list: D018829:Adhesins, Bacterial; D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; C087863:EaeB protein, E coli; D029968:Escherichia coli Proteins; D022361:Escherichia coli Vaccines; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D022641:Shiga Toxin 2; D000069296:Type III Secretion Systems; C073819:eaeA protein, E coli