scholarly journals Current Progress in Developing Subunit Vaccines against Enterotoxigenic Escherichia coli-Associated Diarrhea

2015 ◽  
Vol 22 (9) ◽  
pp. 983-991 ◽  
Author(s):  
Weiping Zhang ◽  
David A. Sack
Keyword(s):  
Escherichia Coli ◽  
Subunit Vaccine ◽  
Vaccine Development ◽  
Enterotoxigenic Escherichia Coli ◽  
Cell Vaccine ◽  
Virulence Determinants ◽  
Subunit Vaccines ◽  
Content Type ◽  
Vaccine Candidates ◽  
Colonization Factor

ABSTRACTDiarrhea continues to be a leading cause of death in children <5 years of age, and enterotoxigenicEscherichia coli(ETEC) is the most common bacterial cause of children's diarrhea. Currently, there are no available vaccines against ETEC-associated diarrhea. Whole-cell vaccine candidates have been under development but require further improvements because they provide inadequate protection and produce unwanted adverse effects. Meanwhile, a newer approach using polypeptide or subunit vaccine candidates focusing on ETEC colonization factor antigens (CFAs) and enterotoxins, the major virulence determinants of ETEC diarrhea, shows substantial promise. A conservative CFA/I adhesin tip antigen and a CFA MEFA (multiepitope fusion antigen) were shown to induce cross-reactive antiadhesin antibodies that protected against adherence by multiple important CFAs. Genetic fusion of toxoids derived from ETEC heat-labile toxin (LT) and heat-stable toxin (STa) induced antibodies neutralizing both enterotoxins. Moreover, CFA-toxoid MEFA polypeptides, generated by fusing CFA MEFA to an STa-LT toxoid fusion, induced antiadhesin antibodies that broadly inhibited adherence of the seven most important ETEC CFAs associated with about 80% of the diarrhea cases caused by ETEC strains with known CFAs. This same antigen preparation also induced antitoxin antibodies that neutralized both toxins that are associated with all cases of ETEC diarrhea. Results from these studies suggest that polypeptide or subunit vaccines have the potential to effectively protect against ETEC diarrhea. In addition, novel adhesins and mucin proteases have been investigated as potential alternatives or, more likely, additional antigens for ETEC subunit vaccine development.

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 TleA, a Tsh-Like Autotransporter Identified in a Human Enterotoxigenic Escherichia coli Strain

2015 ◽  
Vol 83 (5) ◽  
pp. 1893-1903 ◽  
Author(s):  
Daniela Gutiérrez ◽  
Mirka Pardo ◽  
David Montero ◽  
Angel Oñate ◽  
Mauricio J. Farfán ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Genomic Library ◽  
Coli Strain ◽  
Enterotoxigenic Escherichia Coli ◽  
Watery Diarrhea ◽  
Temperature Sensitive ◽  
Content Type ◽  
E Coli ◽  
Colonization Factor ◽  
Adhesion Level

EnterotoxigenicEscherichia coli(ETEC), a leading cause of acute diarrhea, colonizes the intestine by means of adhesins. However, 15 to 50% of clinical isolates are negative for known adhesins, making it difficult to identify antigens for broad-coverage vaccines. The ETEC strain 1766a, obtained from a child with watery diarrhea in Chile, harbors the colonization factor CS23 but is negative for other known adhesins. One clone, derived from an ETEC 1766a genomic library (clone G10), did not produce CS23 yet was capable of adhering to Caco-2 cells. The goal of this study was to identify the gene responsible for this capacity. Random transposon-based mutagenesis allowed the identification of a 4,110-bp gene that codes for a homologue of the temperature-sensitive hemagglutinin (Tsh) autotransporter described in avianE. colistrains (97% identity, 90% coverage) and that is called TleA (Tsh-like ETEC autotransporter) herein. An isogenic ETEC 1766a strain with atleAmutation showed an adhesion level similar to that of the wild-type strain, suggesting that the gene does not direct attachment to Caco-2 cells. However, expression oftleAconferred the capacity for adherence to nonadherentE. coliHB101. This effect coincided with the detection of TleA on the surface of nonpermeabilized bacteria, while, conversely, ETEC 1766a seems to secrete most of the produced autotransporter to the medium. On the other hand, TleA was capable of degrading bovine submaxillary mucin and leukocyte surface glycoproteins CD45 and P-selectin glycoprotein ligand 1 (PSGL-1). These results suggest that TleA promotes colonization of the intestinal epithelium and that it may modulate the host immune response.

scholarly journals Immunizations with Enterotoxigenic Escherichia coli Heat-Stable Toxin Conjugates Engender Toxin-Neutralizing Antibodies in Mice That Also Cross-React with Guanylin and Uroguanylin

2019 ◽  
Vol 87 (7) ◽  
Author(s):  
Yuleima Diaz ◽  
Morten L. Govasli ◽  
Ephrem Debebe Zegeye ◽  
Halvor Sommerfelt ◽  
Hans Steinsland ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Neutralizing Antibodies ◽  
Vaccine Development ◽  
Cross Reactivity ◽  
Enterotoxigenic Escherichia Coli ◽  
Middle Income ◽  
Content Type ◽  
Endogenous Peptides ◽  
Heat Stable ◽  
Important Challenge

ABSTRACT Infection with enterotoxigenic Escherichia coli (ETEC) is a common cause of childhood diarrhea in low- and middle-income countries, as well as of diarrhea among travelers to these countries. In children, ETEC strains secreting the heat-stable toxin (ST) are the most pathogenic, and there are ongoing efforts to develop vaccines that target ST. One important challenge for ST vaccine development is to construct immunogens that do not elicit antibodies that cross-react with guanylin and uroguanylin, which are endogenous peptides involved in regulating the activity of the guanylate cyclase-C (GC-C) receptor. We immunized mice with both human ST (STh) and porcine ST (STp) chemically coupled to bovine serum albumin, and the resulting sera neutralized the toxic activities of both STh and STp. This suggests that a vaccine based on either ST variant can confer cross-protection. However, several anti-STh and anti-STp sera cross-reacted with the endogenous peptides, suggesting that the ST sequence must be altered to reduce the risk of unwanted cross-reactivity. Epitope mapping of four monoclonal anti-STh and six anti-STp antibodies, all of which neutralized both STh and STp, revealed that most epitopes appear to have at least one amino acid residue shared with guanylin or uroguanylin. Despite this, only one monoclonal antibody displayed demonstrable cross-reactivity to the endogenous peptides, suggesting that targeted mutations of a limited number of ST residues may be sufficient to obtain a safe ST-based vaccine.

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 Importance of Heat-Labile Enterotoxin in Colonization of the Adult Mouse Small Intestine by Human Enterotoxigenic Escherichia coli Strains

2006 ◽  
Vol 74 (2) ◽  
pp. 869-875 ◽  
Author(s):  
Kenneth P. Allen ◽  
Mildred M. Randolph ◽  
James M. Fleckenstein
Keyword(s):  
Escherichia Coli ◽  
Small Intestine ◽  
Diarrheal Disease ◽  
Vaccine Development ◽  
Small Animal ◽  
Enterotoxigenic Escherichia Coli ◽  
Colonization Factor ◽  
Heat Stable ◽  
Heat Labile ◽  
Colonization Factor Antigen I

ABSTRACT Enterotoxigenic Escherichia coli (ETEC) infections are a significant cause of diarrheal disease and infant mortality in developing countries. Studies of ETEC pathogenesis relevant to vaccine development have been greatly hampered by the lack of a suitable small-animal model of infection with human ETEC strains. Here, we demonstrate that adult immunocompetent outbred mice can be effectively colonized with the prototypical human ETEC H10407 strain (colonization factor antigen I; heat-labile and heat-stable enterotoxin positive) and that production of heat-labile holotoxin provides a significant advantage in colonization of the small intestine in this model.

scholarly journals Characterization of Heat-Stable (STa) Toxoids of Enterotoxigenic Escherichia coli Fused to Double Mutant Heat-Labile Toxin Peptide in Inducing Neutralizing Anti-STa Antibodies

2014 ◽  
Vol 82 (5) ◽  
pp. 1823-1832 ◽  
Author(s):  
Xiaosai Ruan ◽  
Donald C. Robertson ◽  
James P. Nataro ◽  
John D. Clements ◽  
Weiping Zhang
Keyword(s):  
Escherichia Coli ◽  
Antibody Response ◽  
Neutralizing Antibodies ◽  
Double Mutant ◽  
Vaccine Development ◽  
Enterotoxigenic Escherichia Coli ◽  
Virulence Determinants ◽  
Heat Stable ◽  
Heat Labile ◽  
Fusion Antigen

ABSTRACTA long-standing challenge in developing vaccines against enterotoxigenicEscherichia coli(ETEC), the most common bacteria causing diarrhea in children of developing countries and travelers to these countries, is to protect against heat-stable toxin type Ib (STa or hSTa). STa and heat-labile toxin (LT) are virulence determinants in ETEC diarrhea. LT antigens are often used in vaccine development, but STa has not been included because of its poor immunogenicity and potent toxicity. Toxic STa is not safe for vaccines, but only STa possessing toxicity is believed to be able to induce neutralizing antibodies. However, recent studies demonstrated that nontoxic STa derivatives (toxoids), after being fused to an LT protein, induced neutralizing antibodies and suggested that different STa toxoids fused to an LT protein might exhibit different STa antigenic propensity. In this study, we selected 14 STa toxoids from a mini-STa toxoid library based on toxicity reduction and reactivity to anti-native STa antibodies, and genetically fused each toxoid to a monomeric double mutant LT (dmLT) peptide for 14 STa-toxoid-dmLT toxoid fusions. These toxoid fusions were used to immunize mice and were characterized for induction of anti-STa antibody response. The results showed that different STa toxoids (in fusions) varied greatly in anti-STa antigenicity. Among them, STaN12S, STaN12T, and STaA14Hwere the top toxoids in inducing anti-STa antibodies.In vitroneutralization assays indicated that antibodies induced by the 3×STaN12S-dmLT fusion antigen exhibited the greatest neutralizing activity against STa toxin. These results suggested 3×STaN12S-dmLT is a preferred fusion antigen to induce an anti-STa antibody response and provided long-awaited information for effective ETEC vaccine development.

scholarly journals Functional analysis of colonization factor antigen I positive enterotoxigenic Escherichia coli identifies genes implicated in survival in water and host colonization

2021 ◽  
Vol 7 (6) ◽  
Author(s):  
Moataz Abd El Ghany ◽  
Lars Barquist ◽  
Simon Clare ◽  
Cordelia Brandt ◽  
Matthew Mayho ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Enterotoxigenic Escherichia Coli ◽  
Mammalian Host ◽  
Content Type ◽  
Colonization Factor ◽  
Lipopolysaccharide Biosynthesis ◽  
Common Causes ◽  
Colonization Factor Antigen I ◽  
Factor Antigen

Enterotoxigenic Escherichia coli (ETEC) expressing the colonization pili CFA/I are common causes of diarrhoeal infections in humans. Here, we use a combination of transposon mutagenesis and transcriptomic analysis to identify genes and pathways that contribute to ETEC persistence in water environments and colonization of a mammalian host. ETEC persisting in water exhibit a distinct RNA expression profile from those growing in richer media. Multiple pathways were identified that contribute to water survival, including lipopolysaccharide biosynthesis and stress response regulons. The analysis also indicated that ETEC growing in vivo in mice encounter a bottleneck driving down the diversity of colonizing ETEC populations.

scholarly journals Cross-Reactivity, Epitope Mapping, and Potency of Monoclonal Antibodies to Class 5 Fimbrial Tip Adhesins of Enterotoxigenic Escherichia coli

2020 ◽  
Vol 88 (11) ◽  
Author(s):  
Yang Liu ◽  
Sakina Shahabudin ◽  
Sami Farid ◽  
Lanfong H. Lee ◽  
Annette L. McVeigh ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Monoclonal Antibodies ◽  
Sequence Similarity ◽  
Bacterial Pathogen ◽  
Cross Reactivity ◽  
Enterotoxigenic Escherichia Coli ◽  
Content Type ◽  
Functional Activities ◽  
Colonization Factor ◽  
Protective Antibodies

ABSTRACT Enterotoxigenic Escherichia coli (ETEC) is a leading diarrheagenic bacterial pathogen among travelers and children in resource-limited regions. Adherence to host intestinal cells mediated by ETEC fimbriae is believed to be a critical first step in ETEC pathogenesis. These fimbriae are categorized into related classes based on sequence similarity, with members of the class 5 fimbrial family being the best characterized. The eight related members of the ETEC class 5 fimbrial family are subdivided into three subclasses (5a, 5b, and 5c) that share similar structural arrangements, including a fimbrial tip adhesin. However, sequence variability among the class 5 adhesins may hinder the generation of cross-protective antibodies. To better understand functional epitopes of the class 5 adhesins and their ability to induce intraclass antibody responses, we produced 28 antiadhesin monoclonal antibodies (MAbs) to representative adhesins CfaE, CsbD, and CotD, respectively. We determined the MAb cross-reactivities, localized the epitopes, and measured functional activities as potency in inhibition of hemagglutination induced by class 5 fimbria-bearing ETEC. The MAbs’ reactivities to a panel of class 5 adhesins in enzyme-linked immunosorbent assays (ELISAs) revealed several reactivity patterns, including individual adhesin specificity, intrasubclass specificity, intersubclass specificity, and class-wide cross-reactivity, suggesting that some conserved epitopes, including two conserved arginines, are shared by the class 5 adhesins. However, the cross-reactive MAbs had functional activities limited to strains expressing colonization factor antigen I (CFA/I), coli surface antigen 17 (CS17), or CS1, suggesting that the breadth of functional activities of the MAbs was more restricted than the repertoire of cross-reactivities measured by ELISA. The results imply that multivalent adhesin-based ETEC vaccines or prophylactics need more than one active component to reach broad protection.

scholarly journals The Oral, Live Attenuated Enterotoxigenic Escherichia coli Vaccine ACE527 Reduces the Incidence and Severity of Diarrhea in a Human Challenge Model of Diarrheal Disease

2012 ◽  
Vol 19 (12) ◽  
pp. 1921-1931 ◽  
Author(s):  
Michael J. Darsley ◽  
Subhra Chakraborty ◽  
Barbara DeNearing ◽  
David A. Sack ◽  
Andrea Feller ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Ad Hoc ◽  
Diarrheal Disease ◽  
Enterotoxigenic Escherichia Coli ◽  
Content Type ◽  
Severe Diarrhea ◽  
Colonization Factor ◽  
Human Volunteers ◽  
Colonization Factors ◽  
Further Development

ABSTRACTAn oral, live attenuated, three-strain recombinant bacterial vaccine, ACE527, was demonstrated to generate strong immune responses to colonization factor and toxin antigens of enterotoxigenicEscherichia coli(ETEC) in human volunteers. The vaccine was safe and well tolerated at doses of up to 1011CFU, administered in each of two doses given 21 days apart. These observations have now been extended in a phase 2b study with a total of 70 subjects. Fifty-six of these subjects were challenged 28 days after the second dose of vaccine with the highly virulent ETEC strain H10407 to obtain preliminary indicators of efficacy against disease and to support further development of the vaccine for both travelers and infants in countries where ETEC is endemic. The vaccine had a significant impact on intestinal colonization by the challenge strain, as measured by quantitative fecal culture 2 days after challenge, demonstrating the induction of a functional immune response to the CFA/I antigen. The incidence and severity of diarrhea were also reduced in vaccinees as measured by a number of secondary andad hocendpoints, although the 27% reduction seen in the primary endpoint, moderate to severe diarrhea, was not statistically significant. Together, these observations support the hypothesis that the ACE527 vaccine has a dual mode of action, targeting both colonization factors and the heat-labile enterotoxin (LT), and suggest that it should be further developed for more advanced trials to evaluate its impact on the burden of ETEC disease in field settings.

Sign in / Sign up

Export Citation Format

Share Document