Immunoproteomic Analysis To Identify Shiga Toxin-Producing Escherichia coli Outer Membrane Proteins Expressed during Human Infection

Abstract

b Shiga-toxin producing Escherichia coli (STEC) is the etiologic agent of acute diarrhea, dysentery, and hemolytic-uremic syndrome (HUS). There is no approved vaccine for STEC infection in humans, and antibiotic use is contraindicated, as it promotes Shiga toxin production. In order to identify STEC-associated antigens and immunogenic proteins, outer membrane proteins (OMPs) were extracted from STEC O26:H11, O103, O113:H21, and O157:H7 strains, and commensal E. coli strain HS was used as a control. SDS-PAGE, two-dimensional-PAGE analysis, Western blot assays using sera from pediatric HUS patients and controls, and matrix-assisted laser desorption ionization-tandem time of flight analyses were used to identify 12 immunogenic OMPs, some of which were not reactive with control sera. Importantly, seven of these proteins have not been previously reported to be immunogenic in STEC strains. Among these seven proteins, OmpT and Cah displayed IgG and IgA reactivity with sera from HUS patients. Genes encoding these two proteins were present in a majority of STEC strains. Knowledge of the antigens produced during infection of the host and the immune response to those antigens will be important for future vaccine development.

Comparative Analysis of Immune Responses to Outer Membrane Antigens OMP10, OMP19, and OMP28 of <i>Brucella abortus</i>

“…Therefore, results of this study contribute to the understanding of the immunogenicity of rOMP10 and rOMP19. These OMPs have been generally studied to develop vaccines against diseases caused by various species, including Anaplasma marginale (29), S. enterica (30), Haemophilus parasuis (31), and E. coli (32). Pathogenic infections against host cells and the consequent cytokine production have been investigated thoroughly in the field of immunology and vaccine development (33)(34)(35)(36).…”

Proteome signatures—how are they obtained and what do they teach us?

“…Combining proteomics with the detection of antigens that show immunoreactivity allows for the identification of immunogenic proteins/ peptides expressed during infection (Dennehy and McClean 2012). Most studies have been focused on either cell surface or outer membrane proteins (Montero et al 2014;Newcombe et al 2014;Wu et al 2008b;Zhou et al 2009), as these are the de facto interface for host-pathogen interactions. Additionally, secreted proteins could also be of special interest (Barh et al 2013;Campbell et al 2015;Enany et al 2012;Wang et al 2014b;Wu et al 2008a), as these are also primary antigen targets of the host immune response and include many virulence factors (Dennehy and McClean 2012).…”

Immunization of mice with chimeric antigens displaying selected epitopes confers protection against intestinal colonization and renal damage caused by Shiga toxin-producingEscherichia coli

“…STEC proteins involved in attachment to host tissues are eligible targets for vaccine development, as they determine initial steps during infection; however, the selection of antigens that may provide a broadly and protective immune response among their diverse adhesion and colonization mechanisms is a pivotal point to consider. 11 An additional difficulty for the development of an effective STEC vaccine has been the lack of an animal model of infection that can reproduce the pathologies caused in humans. 12 Despite these limitations, several STEC vaccine candidates have been evaluated in laboratory animals (mice, rats and rabbits) and in cattle, with promising results.…”

“…24 While most of these vaccine candidates are based on LEE-encoded antigens and Stx subunits, there are several antigens encoded outside LEE that are expressed in vivo during human infection that could be suitable targets for vaccine development. 11, 25…”