Experimental vaccine against E. coli O157:H7 for cattle composed by Intimin, EspB and Stx2B. 2017.

CATALDI A A.; ALBANESE A A, ; FIORENTINO G.A, ; PALERMO M S; VILTE D A, ; MARTORELLI L; IBARRA C, ; GARBACCIO S,

Foz de Iguazú, Brazil

Congreso; Congreso International Lacer-Latin American Coalition for Escherichia coli Research. Octubre 23-24. Foz de Iguazú, Brazil; 2017

Lacer-Latin American Coalition for Escherichia coli Research

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 assessthe immunogenic properties of a candidate vaccine consisting on the recombinant proteinsof E. coli O157:H7 IntiminC280, the carboxy-terminal fraction of Intimin γ, EspB and thefusion protein between the B subunit of Stx2 and Brucella Lumazine Synthase (BLS)(BLSStx2B),in Holstein Fresian calves.To accomplish this goal we vaccinated calves with twodoses of different vaccine formulations: 2 antigens (IntiminC280, EspB), 3 antigens (IntiminC280,EspB, BLS-Stx2B), BLS-Stx2B alone and a control non-vaccinated group. All antigenswere expressed as recombinant proteins in E. coli. Specific IgG titres increased invaccinated calves and the inclusion of BLS-Stx2B in the formulation seems to have a stimulatoryeffect on the humoral response to IntiminC280 and EspB after the booster. The neutralizingactivity of antibodies against these two antigens was assessed in Red Blood Celllysis assays and adherence to Hep-2 cells as a correlate of T3SS activity. Both sera fromanimals vaccinated with 2 or 3 antigens inhibited both virulence properties. Serologicalresponse to Stx2 was observed in animals vaccinated only with BLS-Stx2B and with 3 antigensand neutralization of Stx2 cytotoxicity was also observed in both groups. In conclusion,immunization of calves with BLS-Stx2B, IntiminC280 and EspB elicited a potent humoralresponse able to neutralize Shiga toxin 2 cytotoxity and the T3SS virulence properties invitro. These results suggest that this formulation is a good candidate vaccine to reduceSTEC shedding in cattle and needs to be further assessed in vivo.