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Decreased STEC shedding by cattle following passive and active vaccination based on recombinant Escherichia coli Shiga toxoids

Schmidt, Nadine, Barth, Stefanie A., Frahm, Jana, Meyer, Ulrich, Dänicke, Sven, Geue, Lutz, Menge, Christian
Veterinary research 2018 v.49 no.1 pp. 28
Shiga toxin, Shiga toxin-producing Escherichia coli, antibodies, blood serum, calves, cell-mediated immunity, colostrum, cows, farms, feces, flow cytometry, milk replacer, placebos, toxoids, vaccination, veterinary medicine, virulence, vitamin E
The principal virulence factor of Shiga toxin (Stx)-producing Escherichia coli (STEC), the eponymous Stx, modulates cellular immune responses in cattle, the primary STEC reservoir. We examined whether immunization with genetically inactivated recombinant Shiga toxoids (rStx1MUT/rStx2MUT) influences STEC shedding in a calf cohort. A group of 24 calves was passively (colostrum from immunized cows) and actively (intra-muscularly at 5ᵗʰ and 8ᵗʰ week) vaccinated. Twenty-four calves served as unvaccinated controls (fed with low anti-Stx colostrum, placebo injected). Each group was divided according to the vitamin E concentration they received by milk replacer (moderate and high supplemented). The effective transfer of Stx-neutralizing antibodies from dams to calves via colostrum was confirmed by Vero cell assay. Serum antibody titers in calves differed significantly between the vaccinated and the control group until the 16ᵗʰ week of life. Using the expression of activation marker CD25 on CD4⁺CD45RO⁺ cells and CD8αʰⁱCD45RO⁺ cells as flow cytometry based read-out, cells from vaccinated animals responded more pronounced than those of control calves to lysates of STEC and E. coli strains isolated from the farm as well as to rStx2MUT in the 16ᵗʰ week. Summarized for the entire observation period, less fecal samples from vaccinated calves were stx₁ and/or stx₂ positive than samples from control animals when calves were fed a moderate amount of vitamin E. This study provides first evidence, that transfer to and induction in young calves of Stx-neutralizing antibodies by Shiga toxoid vaccination offers the opportunity to reduce the incidence of stx-positive fecal samples in a calf cohort.