Recombinant Shiga Toxin B-Subunit-Keyhole Limpet Hemocyanin Conjugate Vaccine Protects Mice from Shigatoxemia

Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Canada.
Infection and Immunity (Impact Factor: 3.73). 10/2005; 73(10):6523-9. DOI: 10.1128/IAI.73.10.6523-6529.2005
Source: PubMed


Enterohemorrhagic Escherichia coli (EHEC) causes hemorrhagic colitis in humans and, in a subgroup of infected subjects, a more serious condition called hemolytic-uremic syndrome (HUS). These conditions arise because EHEC produces two antigenically distinct forms of Shiga toxin (Stx), called Stx1 and Stx2. Despite this, the production of Stx2 by virtually all EHEC serotypes and the documented role this toxin plays in HUS make it an attractive vaccine candidate. Previously, we assessed the potential of a purified recombinant Stx2 B-subunit preparation to prevent Shigatoxemia in rabbits. This study revealed that effective immunization could be achieved only if endotoxin was included with the vaccine antigen. Since the presence of endotoxin would be unacceptable in a human vaccine, the object of the studies described herein was to investigate ways to safely augment, in mice, the immunogenicity of the recombinant Stx2 B subunit containing <1 endotoxin unit per ml. The study revealed that sera from mice immunized with such a preparation, conjugated to keyhole limpet hemocyanin and administered with the Ribi adjuvant system, displayed the highest Shiga toxin 2 B-subunit-specific immunoglobulin G1 (IgG1) and IgG2a enzyme-linked immunosorbent assay titers and cytotoxicity-neutralizing activities in Ramos B cells. As well, 100% of the mice vaccinated with this preparation were subsequently protected from a lethal dose of Stx2 holotoxin. These results support further evaluation of a Stx2 B-subunit-based human EHEC vaccine.

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Available from: Glen D Armstrong, Aug 06, 2014
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    • "Moreover, substantial animal data indicate that vaccination with CTB or LTB subunits is safe and effective for the prevention of CT- or LT-associated diarrhea [7, 10]. The B subunits of Stx1 and Stx2 have also been reported to be immunogenic and proposed as candidate vaccine antigens [6, 14, 15]. In addition, the B subunit-encoding gene is much smaller than the holotoxin gene, which will be advantageous for producing of recombinant proteins by gene transduction into plant cells [16]. "
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    ABSTRACT: Porcine edema disease (ED) is a communicable disease of shoats caused by infection with Shiga toxin (Stx)-producing Escherichia coli. Stx2e is classified as a 1A5B-type toxin and is a decisive virulence determinant of ED. The single A subunit of Stx2e possesses enzymatic activity and is accompanied by a pentamer of B subunits, which binds to the host receptor and delivers the A subunit into the cell. In the present study, we used a mouse model to evaluate the immunogenicity of 3 ED vaccine candidates: a non-toxic mutant holotoxin mStx2e and 2 Stx2eB-based fusion proteins, Stx2eA2B-His and Stx2eB-His. Systemic inoculation of mice with mStx2e- and the Stx2eB-derived antigens induced anti-Stx2e IgG responses that were fully and partially capable of neutralizing Stx2e cellular cytotoxicity, respectively. Intranasal immunization with mStx2e protected the mice from subsequent intraperitoneal challenge with a lethal dose of Stx2e, whereas immunization with Stx2eA2B-His and Stx2eB-His afforded partial protection. Analysis of serum cytokines revealed that mStx2e, but not the Stx2eB-based antigens, was capable of inducing a Th2-type immune response. These results suggest that although the Stx2eB-based antigens elicited an immune response to Stx2e, they did so through a different mechanism to the Th2-type response induced by mStx2e.
    Journal of Veterinary Medical Science 06/2013; 75(10). DOI:10.1292/jvms.13-0118 · 0.78 Impact Factor
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    • "Recently Bretschneider et al. (2007) demonstrated that cattle respond serologically to intimin and EspB during the course of an experimental infection with E. coli O157:H7. Various vaccine formulations against E. coli O157:H7 infections have been assayed in cattle (Babiuk et al., 2008; Dziva et al., 2007; McNeilly et al., 2008, 2010; Potter et al., 2004; Smith et al., 2008; van Diemen et al., 2007; Vilte et al., 2011) and other animal models (Agin et al., 2005; Cataldi et al., 2008; Dean-Nystrom et al., 2002; Judge et al., 2004; Marcato et al., 2005; Wen et al., 2006) with variable results. Vaccination with bacterial colonization factors has been proposed as a strategy to prevent E. coli O157:H7 infection. "
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    ABSTRACT: Cattle are the main reservoir of enterohemorrhagic Escherichia coli O157:H7, a bacterium that, in humans, causes hemorrhagic colitis and hemolytic uremic syndrome (HUS), a life-threatening disease, especially in children and older people. Therefore, the development of vaccines preventing colonization of cattle by E. coli O157:H7 could be a main tool for an HUS control program. In the present study, we evaluated bacterial ghosts (BGs) of E. coli O157:H7 as an experimental vaccine against this pathogen. BGs are empty envelopes of Gram-negative bacteria, which retain the morphological surface make-up of their living counterparts and are produced by controlled expression of the cloned protein E, which causes loss of all the cytoplasm content. In this work, E. coli O157:H7 BGs were used for subcutaneous immunization of calves. The vaccinated animals elicited significant levels of BG-specific IgG but not IgA antibodies in serum. Low levels of IgA and IgG antibodies against BGs were detected in saliva from vaccinated animals. Following oral challenge with E. coli O157:H7, a significant reduction in both the duration and total bacterial shedding was observed in vaccinated calves compared to the nonimmunized group. We demonstrated that systemic vaccination with E. coli O157 BGs provides protection in a bovine experimental model. Further research is needed to reach a higher mucosal immune response leading to an optimal vaccine.
    Veterinary Immunology and Immunopathology 04/2012; 146(2):169-76. DOI:10.1016/j.vetimm.2012.03.002 · 1.54 Impact Factor
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    • "It has been proposed that an acellular vaccine consisting of a nontoxic Stx2B or of it with other proteins [17] might provide safe and effective protection against the most severe complications of EHEC infections [18]. However, as the antigenecity of Stx2B is very low, it has also been reported that the induction of an effective immune response to Stx2B is difficult to achieve [19] [20]. "
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    ABSTRACT: Escherichia coli O157:H7 produces Stx1 and Stx2 causing severe diseases. Their B subunits (StxBs) are useful for a vaccine but exhibit low immunogenicity, especially Stx2B. Nasal vaccination with StxBs plus cholera toxin induces only serum anti-Stx1B antibodies in mice. However, nasal administration of a mutant of E. coli enterotoxin and His-tagged Stx2B induced serum antibodies neutralizing Stx2 in vitro or in vivo and mucosal IgA antibodies in lungs. As His-tagged Stx2B showed five or three polymers in gel filtration chromatography, His-tagged Stx2B forms smaller tertiary structure than the native one and is effective for preventing Stx2 toxemia as a nasal vaccine.
    Vaccine 02/2008; 26(4):469-76. DOI:10.1016/j.vaccine.2007.11.038 · 3.62 Impact Factor
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