CONICET | Buscador de Institutos y Recursos Humanos

IFIBIO HOUSSAY 25014

INSTITUTO DE FISIOLOGIA Y BIOFISICA BERNARDO HOUSSAY

Unidad Ejecutora - UE

información general

recursos humanos

líneas de investigación

servicios tecnológicos

artículos

libros

capítulos de libros

congresos y reuniones científicas

informe técnico

congresos y reuniones científicas

Título:

Efficacy of a recombinant Intimin, EspB and Shiga toxin 2B vaccine in calves challenged with Escherichia coli O157:H7.

Autor/es:

IBARRA CRISTINA; GARBACCIO SERGIO; GARIMANO NICOLÁS; PALERMO MARINA; BARTH F; FIORENTINO GABRIELA; CATALDI ANGEL; MENGE CRISTIAN; VILTE DANIEL A; MARTORELLI LUISINA

Lugar:

Florencia

Reunión:

Congreso; 10th International Symposium on Shiga Toxin (Verocytotoxin)-producing Escherichia coli infections.; 2018

Institución organizadora:

VTEC2018

Resumen:

Escherichia coli O157:H7 is a zoonoticpathogen of global importance and the serotype of Shiga toxin-producing E. coli (STEC) most frequentlyassociated with Hemolytic Uremic Syndrome in humans. The main STEC reservoir iscattle. Vaccination of calves with the carboxy-terminal portion of Intimin γ (IntC280) and EspB can reduce E. coliO157:H7 fecal shedding after experimental challenge. Shiga toxin (Stx) exertslocal immunosuppressive effects in the bovine intestine and Stx2B fused toBrucella Lumazine Synthase (BLS-Stx2B) induces Stx2-neutralizing antibodies. Todetermine if an immune response against Stx could improve a vaccine?s effect onfecal shedding, fifteen 4-month-old male Holstein Friesian calves wereimmunized with EspB + IntC280 (n = 5); EspB + IntC280 + BLS-Stx2B (n = 5) orkept as controls (n = 5). Blood samples were taken periodically to evaluatehumoral responses, Interferon gamma secretion in stimulated whole blood andcytokine transcription in stimulated peripheral blood mononuclear cells. At 24days post vaccination (dpv), calves were intragastrically challenged with 109CFU of E. coli O157:H7. Sheddingof E. coli O157:H7 was assessedin recto-anal mucosal swabs by direct plating and enrichment followed byimmunomagnetic separation and multiplex PCR. Calves were euthanized 15 daysafter the challenge and recto-anal junction (RAJ), ileum and cecum segmentswere obtained to assess mucosal antibodies. The presence of the bacteria wasevaluated in RAJ. Vaccination induced a significant increase of IntC280 andEspB specific antibodies in serum and intestinal mucosa in both vaccinatedgroups. Antibodies against Stx2B were detected in serum and intestinal mucosaof animals vaccinated with 3 antigens. Sera and intestinal homogenates fromileum, cecum and recto-anal junction were able to neutralize Stx2 verocytotoxicity,significantly different from the control group and from animals vaccinated with2 antigens. Application of both vaccines reduced E. coli O157:H7 shedding compared to the control group. Theaddition of Stx2B to the vaccine formulation did not result in a level of protectionsuperior to the one conferred by IntC280 and EspB alone in the first weeksafter experimental infection.In spite of the fact that no higher protectionwas observed when Stx2B was added to the vaccine formulation during fifteendays following experimental challenge, it remains to be determined if inclusionof Stx2B in the vaccine alters E. coli O157:H7 shedding patternin the long termand after recurrent low dose exposure as occuring in cattle herds. Based onthis evidence it is necessary to pursue the search for alternatives to improvethe elicitation of mucosal immune responses against Stx2, in order to reduce colonizationof the bovine gastrointestinal tract by these zoonotic bacteria.