scholarly journals The EtpA Exoprotein of Enterotoxigenic Escherichia coli Promotes Intestinal Colonization and Is a Protective Antigen in an Experimental Model of Murine Infection

2008 ◽  
Vol 76 (5) ◽  
pp. 2106-2112 ◽  
Author(s):  
Koushik Roy ◽  
David Hamilton ◽  
Kenneth P. Allen ◽  
Mildred P. Randolph ◽  
James M. Fleckenstein
Keyword(s):  
Escherichia Coli ◽  
Immune Responses ◽  
Vaccine Development ◽  
Protective Antigen ◽  
Protective Efficacy ◽  
Enterotoxigenic Escherichia Coli ◽  
Deletion Mutants ◽  
Diverse Group ◽  
Intestinal Colonization

ABSTRACT The enterotoxigenic Escherichia coli (ETEC) strains are major causes of morbidity and mortality due to diarrheal illness in developing countries. At present, there is no broadly protective vaccine for this diverse group of pathogens. The EtpA protein, identified in ETEC H10407 in a recent search for candidate immunogens, is a large glycosylated exoprotein secreted via two-partner secretion (TPS). Similar to structurally related molecules, EtpA functions in vitro as an adhesin. The studies reported here use a recently developed murine model of ETEC intestinal colonization to examine the immunogenicity and protective efficacy of EtpA. We report that mice repeatedly exposed to ETEC are protected from subsequent colonization and that they mount immune responses to both EtpA and its presumed two-partner secretion transporter (EtpB) during the course of experimental infection. Furthermore, isogenic etpA deletion mutants were impaired in the colonization of mice, and intranasal immunization of mice with recombinant EtpA conferred protection against ETEC H10407 in this model. Together, these data suggest that EtpA is required for optimal colonization of the intestine, findings paralleling those of previous in vitro studies demonstrating its role in adherence. EtpA and other TPS proteins may be viable targets for ETEC vaccine development.

scholarly journals Immunogenicity and Protective Efficacy against Enterotoxigenic Escherichia coli Colonization following Intradermal, Sublingual, or Oral Vaccination with EtpA Adhesin

2016 ◽  
Vol 23 (7) ◽  
pp. 628-637 ◽  
Author(s):  
Qingwei Luo ◽  
Tim J. Vickers ◽  
James M. Fleckenstein
Keyword(s):  
Escherichia Coli ◽  
Vaccine Development ◽  
Protective Antigen ◽  
Protective Efficacy ◽  
Enterotoxigenic Escherichia Coli ◽  
Oral Vaccination ◽  
Content Type ◽  
Degree Of Protection ◽  
Alternative Routes

EnterotoxigenicEscherichia coli(ETEC) strains are a common cause of diarrhea. Extraordinary antigenic diversity has prompted a search for conserved antigens to complement canonical approaches to ETEC vaccine development. EtpA, an immunogenic extracellular ETEC adhesin relatively conserved in the ETEC pathovar, has previously been shown to be a protective antigen following intranasal immunization. These studies were undertaken to explore alternative routes of EtpA vaccination that would permit use of a double mutant (R192G L211A) heat-labile toxin (dmLT) adjuvant. Here, oral vaccination with EtpA adjuvanted with dmLT afforded significant protection against small intestinal colonization, and the degree of protection correlated with fecal IgG, IgA, or total fecal antibody responses to EtpA. Sublingual vaccination yielded compartmentalized mucosal immune responses with significant increases in anti-EtpA fecal IgG and IgA, and mice vaccinated via this route were also protected against colonization. In contrast, while intradermal (i.d.) vaccination achieved high levels of both serum and fecal antibodies against both EtpA and dmLT, mice vaccinated via the i.d. route were not protected against subsequent colonization and the avidity of serum IgG and IgA EtpA-specific antibodies was significantly lower after i.d. immunization compared to other routes. Finally, we demonstrate that antiserum from vaccinated mice significantly impairs binding of LT to cognate GM1 receptors and shows near complete neutralization of toxin delivery by ETECin vitro. Collectively, these data provide further evidence that EtpA could complement future vaccine strategies but also suggest that additional effort will be required to optimize its use as a protective immunogen.

scholarly journals Cooperative Role of Antibodies against Heat-Labile Toxin and the EtpA Adhesin in Preventing Toxin Delivery and Intestinal Colonization by Enterotoxigenic Escherichia coli

2012 ◽  
Vol 19 (10) ◽  
pp. 1603-1608 ◽  
Author(s):  
Koushik Roy ◽  
David J. Hamilton ◽  
James M. Fleckenstein
Keyword(s):  
Escherichia Coli ◽  
Diarrheal Disease ◽  
Vaccine Development ◽  
Enterotoxigenic Escherichia Coli ◽  
Intestinal Colonization ◽  
Content Type ◽  
Heat Labile

ABSTRACTEnterotoxigenicEscherichia coli(ETEC) is an important cause of diarrheal disease in developing countries, where it is responsible for hundreds of thousands of deaths each year. Vaccine development for ETEC has been hindered by the heterogeneity of known molecular targets and the lack of broad-based sustained protection afforded by existing vaccine strategies. In an effort to explore the potential role of novel antigens in ETEC vaccines, we examined the ability of antibodies directed against the ETEC heat-labile toxin (LT) and the recently described EtpA adhesin to prevent intestinal colonizationin vivoand toxin delivery to epithelial cellsin vitro. We demonstrate that EtpA is required for the optimal delivery of LT and that antibodies against this adhesin play at least an additive role in preventing delivery of LT to target intestinal cells when combined with antibodies against either the A or B subunits of the toxin. Moreover, vaccination with a combination of LT and EtpA significantly impaired intestinal colonization. Together, these results suggest that the incorporation of recently identified molecules such as EtpA could be used to enhance current approaches to ETEC vaccine development.

scholarly journals Immunogenicity and protective efficacy of enterotoxigenic Escherichia coli (ETEC) total RNA against ETEC challenge in a mouse model

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mandi Liu ◽  
Yue Zhang ◽  
Di Zhang ◽  
Yun Bai ◽  
Guomei Liu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Mouse Model ◽  
Immune Responses ◽  
Protective Efficacy ◽  
Enterotoxigenic Escherichia Coli ◽  
Economic Losses ◽  
Th2 Response ◽  
Total Rna ◽  
Etec Infection

AbstractEnterotoxigenic Escherichia coli (ETEC), an essential cause of post-weaning diarrhea (PWD) in piglets, leads to significant economic losses to the pig industry. The present study aims to identify the role of ETEC total RNA in eliciting immune responses to protect animals against ETEC infection. The results showed that the total RNA isolated from pig-derived ETEC K88ac strain effectively stimulated the IL-1β secretion of porcine intestinal epithelial cells (IPEC-J2). The mouse model immunized with ETEC total RNA via intramuscular injection (IM) or oral route (OR) was used to evaluate the protective efficiency of the ETEC total RNA. The results suggested that 70 μg ETEC total RNA administered by either route significantly promoted the production of the serum IL-1β and K88ac specific immunoglobulins (IgG, IgM, and IgA). Besides, the ETEC RNA administration augmented strong mucosal immunity by elevating K88ac specific IgA level in the intestinal fluid. Intramuscularly administered RNA induced a Th1/Th2 shift toward a Th2 response, while the orally administered RNA did not. The ETEC total RNA efficiently protected the animals against the ETEC challenge either by itself or as an adjuvant. The histology characterization of the small intestines also suggested the ETEC RNA administration protected the small intestinal structure against the ETEC infection. Particularly of note was that the immunity level and protective efficacy caused by ETEC RNA were dose-dependent. These findings will help understand the role of bacterial RNA in eliciting immune responses, and benefit the development of RNA-based vaccines or adjuvants.

Ability ofEscherichia coliO157:H7 isolates to colonize the intestinal tract of conventional adult CD1 mice is transient

2001 ◽  
Vol 47 (1) ◽  
pp. 91-95 ◽  
Author(s):  
J Wayne Conlan ◽  
Sonia L Bardy ◽  
Rhonda KuoLee ◽  
Ann Webb ◽  
Malcolm B Perry
Keyword(s):  
Escherichia Coli ◽  
Mouse Model ◽  
Intestinal Tract ◽  
Vaccine Development ◽  
Escherichia Coli O157 ◽  
Intestinal Colonization ◽  
E Coli ◽  
Cd1 Mice ◽  
A Current

In an attempt to improve upon a current mouse model of intestinal colonization by Escherichia coli O157:H7 used in this laboratory for vaccine development, nine clinical isolates of the pathogen were screened for their ability to persist in the intestinal tract of conventional adult CD-1 mice. None of the test isolates of E. coli O157:H7 were capable of colonizing these mice for a period of more than two weeks. Most of the isolates appeared to be benign for the experimental host, but one isolate was lethal. This virulence correlated with the ability of the latter isolate to produce large quantities of Shiga-like toxin 2 in vitro.

scholarly journals Human Experimental Challenge With Enterotoxigenic Escherichia coli Elicits Immune Responses to Canonical and Novel Antigens Relevant to Vaccine Development

2018 ◽  
Vol 218 (9) ◽  
pp. 1436-1446 ◽  
Author(s):  
Subhra Chakraborty ◽  
Arlo Randall ◽  
Tim J Vickers ◽  
Doug Molina ◽  
Clayton D Harro ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Immune Responses ◽  
Vaccine Development ◽  
Enterotoxigenic Escherichia Coli ◽  
Experimental Challenge

scholarly journals Characterization of Two Non-Locus of Enterocyte Effacement-Encoded Type III-Translocated Effectors, NleC and NleD, in Attaching and Effacing Pathogens

2005 ◽  
Vol 73 (12) ◽  
pp. 8411-8417 ◽  
Author(s):  
Olivier Marchés ◽  
Siouxsie Wiles ◽  
Francis Dziva ◽  
Roberto M. La Ragione ◽  
Stephanie Schüller ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Secretion System ◽  
Host Cells ◽  
Deletion Mutants ◽  
Intestinal Colonization ◽  
Type Iii ◽  
Enterocyte Effacement

ABSTRACT Intestinal colonization by enteropathogenic and enterohemorrhagic Escherichia coli requires the locus of enterocyte effacement-encoded type III secretion system. We report that NleC and NleD are translocated into host cells via this system. Deletion mutants induced attaching and effacing lesions in vitro, while infection of calves or lambs showed that neither gene was required for colonization.

scholarly journals Neutralizing Anti-Heat-Stable Toxin (STa) Antibodies Derived from Enterotoxigenic Escherichia coli Toxoid Fusions with STa Proteins Containing N12S, L9A/N12S, or N12S/A14T Mutations Show Little Cross-Reactivity with Guanylin or Uroguanylin

2017 ◽  
Vol 84 (2) ◽  
Author(s):  
Qiangde Duan ◽  
Jiachen Huang ◽  
Nan Xiao ◽  
Hyesuk Seo ◽  
Weiping Zhang
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Vaccine Development ◽  
Cross Reactivity ◽  
Enterotoxigenic Escherichia Coli ◽  
Content Type ◽  
Renal Epithelial Cells ◽  
Severe Diarrhea ◽  
Heat Stable

ABSTRACT Heat-stable toxin (STa)-producing enterotoxigenic Escherichia coli (ETEC) strains are a top cause of moderate-to-severe diarrhea in children from developing countries and a common cause of travelers' diarrhea. Recent progress in using STa toxoids and toxoid fusions to induce neutralizing anti-STa antibodies has accelerated ETEC vaccine development. However, concern remains regarding whether the derived anti-STa antibodies cross-react with STa-like guanylin and uroguanylin, two guanylate cyclase C (GC-C) ligands regulating fluid and electrolyte transportation in human intestinal and renal epithelial cells. To further divert STa from guanylin and uroguanylin structurally and antigenically and to eliminate anti-STa antibody cross-reactivity with guanylin and uroguanylin, we mutated STa at the 9th (leucine), 12th (asparagine), and 14th (alanine) residues for the double and triple mutants STaL9A/N12S, STaL9A/A14H, STaN12S/A14T, and STaL9A/N12S/A14H. We then fused each STa mutant (three copies) to a monomeric heat-labile toxin (LT) mutant (mnLTR192G/L211A) for the toxoid fusions 3×STaL9A/N12S-mnLTR192G/L211A, 3×STaL9A/A14H-mnLTR192G/L211A, 3×STaN12S/A14T-mnLTR192G/L211A, and 3×STaL9A/N12S/A14H-mnLTR192G/L211A; examined each fusion for anti-STa immunogenicity; and assessed the derived antibodies for in vitro neutralization activity against STa toxicity and for cross-reactivity with guanylin and uroguanylin. Mice subcutaneously immunized with each fusion protein developed anti-STa antibodies, and the antibodies derived from 3×STaN12S-mnLTR192G/L211A, 3×STaL9A/N12S-mnLTR192G/L211A, or 3×STaN12S/A14T-mnLTR192G/L211A prevented STa from the stimulation of intracellular cGMP in T-84 cells. Competitive enzyme-linked immunosorbent assays (ELISAs) showed that guanylin and uroguanylin hardly blocked the binding of anti-STa antibodies to the coated STa-ovalbumin conjugate. These results indicated that antibodies derived from 3×STaN12S-mnLTR192G/L211A, 3×STaL9A/N12S-mnLTR192G/L211A, or 3×STaN12S/A14T-mnLTR192G/L211A neutralized STa and had little cross-reactivity with guanylin and uroguanylin, suggesting that these toxoid fusions are suitable antigens for ETEC vaccines. IMPORTANCE Enterotoxigenic Escherichia coli (ETEC) strains are a leading cause of children's diarrhea and travelers' diarrhea. Currently, there is no licensed vaccine against ETEC diarrhea. One key challenge is to identify safe antigens to induce antibodies neutralizing the key STa without cross-reacting with guanylin and uroguanylin, two important ligands controlling homeostasis in human intestinal and renal epithelial cells. In this study, we generated nontoxic fusion antigens that induced antibodies that neutralize STa enterotoxicity in vitro and do not cross-react with guanylin or uroguanylin. These fusions have become the preferred antigens for the development of ETEC vaccines to potentially prevent the deaths of hundreds of thousands of young children and hundreds of millions of diarrheal cases each year.

scholarly journals Characterization of Mucosal Immune Responses to Enterotoxigenic Escherichia coli Vaccine Antigens in a Human Challenge Model: Response Profiles after Primary Infection and Homologous Rechallenge with Strain H10407

2015 ◽  
Vol 23 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Subhra Chakraborty ◽  
Clayton Harro ◽  
Barbara DeNearing ◽  
Malathi Ram ◽  
Andrea Feller ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Immune Response ◽  
Immune Responses ◽  
Vaccine Development ◽  
Lavage Fluid ◽  
Antibody Responses ◽  
Enterotoxigenic Escherichia Coli ◽  
Effective Vaccine ◽  
Content Type ◽  
Mucosal Immune Responses

ABSTRACTEnterotoxigenicEscherichia coli(ETEC) bacteria are the most common bacterial cause of diarrhea in children in resource-poor settings as well as in travelers. Although there are several approaches to develop an effective vaccine for ETEC, no licensed vaccines are currently available. A significant challenge to successful vaccine development is our poor understanding of the immune responses that correlate best with protection against ETEC illness. In this study, ETEC-specific mucosal immune responses were characterized and compared in subjects challenged with ETEC strain H10407 and in subjects rechallenged with the homologous organism. IgA responses to lipopolysaccharide (LPS), heat-labile toxin B subunit (LTB), and colonization factor antigen I (CFA/I) in antibody in lymphocyte supernatant (ALS), feces, lavage fluid, and saliva samples were evaluated. In all assay comparisons, ALS was the most sensitive indicator of a local immune response, but serum IgA was also a useful indirect marker of immune response to oral antigens. Volunteers challenged and then rechallenged with strain H10407 were protected from illness following rechallenge. Comparing mucosal antibody responses after primary and homologous rechallenge, protection against disease was reflected in reduced antibody responses to key ETEC antigens and in reduced fecal shedding of the H10407 challenge strain. Subjects challenged with strain H10407 mounted stronger antibody responses to LPS and LTB than subjects in the rechallenge group, while responses to CFA/I in the rechallenge group were higher than in the challenge group. We anticipate that this study will help provide an immunological benchmark for the evaluation of ETEC vaccines and immunization regimens in the future.

scholarly journals EatA, an Immunogenic Protective Antigen of Enterotoxigenic Escherichia coli, Degrades Intestinal Mucin

2013 ◽  
Vol 82 (2) ◽  
pp. 500-508 ◽  
Author(s):  
Pardeep Kumar ◽  
Qingwei Luo ◽  
Tim J. Vickers ◽  
Alaullah Sheikh ◽  
Warren G. Lewis ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protective Antigen ◽  
Shigella Flexneri ◽  
Enterotoxigenic Escherichia Coli ◽  
Effective Vaccine ◽  
Major Protein ◽  
Passenger Domain ◽  
Content Type ◽  
Intestinal Mucin

ABSTRACTEnterotoxigenicEscherichia coli(ETEC) is a major cause of morbidity and mortality due to infectious diarrhea in developing countries for which there is presently no effective vaccine. A central challenge in ETEC vaccinology has been the identification of conserved surface antigens to formulate a broadly protective vaccine. Here, we demonstrate that EatA, an immunogenic secreted serine protease of ETEC, contributes to virulence by degrading MUC2, the major protein present in the small intestinal mucous layer, and that removal of this barrierin vitroaccelerates toxin access to the enterocyte surface. In addition, we demonstrate that vaccination with the recombinant secreted passenger domain of EatA (rEatAp) elicits high titers of antibody and is protective against intestinal infection with ETEC. These findings may have significant implications for development of both subunit and live-attenuated vaccines against ETEC and other enteric pathogens, includingShigella flexneri, that express similar proteins.

scholarly journals Impact of lower challenge doses of enterotoxigenic Escherichia coli on clinical outcome, intestinal colonization and immune responses in adult volunteers

2018 ◽  
Vol 12 (4) ◽  
pp. e0006442 ◽  
Author(s):  
Subhra Chakraborty ◽  
Clayton Harro ◽  
Barbara DeNearing ◽  
Jessica Brubaker ◽  
Sean Connor ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Clinical Outcome ◽  
Immune Responses ◽  
Enterotoxigenic Escherichia Coli ◽  
Intestinal Colonization ◽  
Adult Volunteers
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