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Brachyspira (B.) hyodysenteriae the causative agent of swine dysentery (SD) has been divided into 9 serotypes on basis of its lipooligosaccharide (LOS). Knowledge on circulating serotypes in Europe, however, is rare. Regarding that immunity to SD is serotype specific an update of B. hyodysenteriae serotyping was undertaken. A LOS band of 10 to 25kDa was identified being appropriate for this purpose. Isolates from Germany, Spain, Denmark, USA and Japan were characterized in the immunoblot by sera raised to serotypes 1 through 7, serogroups H and I (reference strains) and to eight German strains. In total, 57 (51%) isolates responded to at least one of the antisera. Regarding German isolates (n=75) only 35 (46.7%) were identified but mainly by antisera to German strains. Positive Spanish isolates (12 of 17) yielded similar results. In contrast, positively reacting Danish isolates (9 of 12) were mainly identified by antisera to the reference strains as it was the case for recent U.S. (1 of 8) and Japanese isolates (3 of 5). Results indicate that B. hyodysenteriae has a high degree of serological heterogeneity that has probably differently developed in diverse geographical areas over time. This situation represents a challenge for vaccine development., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Shiga toxin (Stx)-producing Escherichia coli (STEC) infections in cattle are asymptomatic; however, Stx impairs the initiation of an adaptive immune response by targeting bovine peripheral and intraepithelial lymphocytes. As presumptive bovine mucosal macrophages (Mø) are also sensitive to Stx, STEC may even exert immune modulatory effects by acting on steps preceding lymphocyte activation at the Mø level. We therefore studied the expression of the Stx receptor (CD77), cellular phenotype and functions after incubation of primary bovine monocyte-derived Mø with purified Stx1. A significant portion of bovine Mø expressed CD77 on their surface, with the recombinant B-subunit of Stx1 binding to >50% of the cells. Stx1 down-regulated significantly surface expression of CD14, CD172a and co-stimulatory molecules CD80 and CD86 within 4 h of incubation, while MHC-II expression remained unaffected. Furthermore, incubation of Mø with Stx1 increased significantly numbers of transcripts for IL-4, IL-6, IL-10, IFN-γ, TNF-α, IL-8 and GRO-α but not for IL-12, TGF-β, MCP-1 and RANTES. In the course of bovine STEC infections, Stx1 appears to induce in Mø a mixed response pattern reminiscent of regulatory Mø, which may amplify the direct suppressive effect of the toxin on lymphocytes., (© The Author(s) 2015.)

Cattle are the most important reservoir for enterohemorrhagic Escherichia coli (EHEC), a subset of shigatoxigenic E. coli (STEC) capable of causing life-threatening infectious diseases in humans. In cattle, Shiga toxins (Stx) suppress the immune system thereby promoting long-term STEC shedding. First infections of animals at calves' age coincide with the lack of Stx-specific antibodies. We hypothesize that vaccination of calves against Shiga toxins prior to STEC infection may help to prevent the establishment of a persistent type of infection. The objectives of this study were to generate recombinant Shiga toxoids (rStx1mut & rStx2mut) by site-directed mutagenesis and to assess their immunomodulatory, antigenic, and immunogenic properties. Cultures of bovine primary immune cells were used as test systems. In ileal intraepithelial lymphocytes both, recombinant wild type Stx1 (rStx1WT) and rStx2WT significantly induced transcription of IL-4 mRNA. rStx1WT and rStx2WT reduced the expression of Stx-receptor CD77 (syn. Globotriaosylceramide, Gb3) on B and T cells from peripheral blood and of CD14 on monocyte-derived macrophages. At the same concentrations, rStx1mut and rStx2mut exhibited neither of these effects. Antibodies in sera of cattle naturally infected with STEC recognized the rStxmut toxoids equally well as the recombinant wild type toxins. Immunization of calves with rStx1mut plus rStx2mut led to induction of antibodies neutralizing Stx1 and Stx2. While keeping their antigenicity and immunogenicity recombinant Shiga toxoids are devoid of the immunosuppressive properties of the corresponding wild type toxins in cattle and candidate vaccines to mitigate long-term STEC shedding by the reservoir host.