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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    • "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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    • "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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