Protective efficacy of a novel multivalent vaccine in the prevention of diarrhea induced by enterotoxigenic Escherichia coli in a murine model

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.

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Protective immunity of a Multivalent Vaccine Candidate against piglet diarrhea caused by enterotoxigenic Escherichia coli (ETEC) in a pig model

Vaccine ◽

10.1016/j.vaccine.2017.12.026 ◽

2018 ◽

Vol 36 (5) ◽

pp. 723-728 ◽

Cited By ~ 17

Author(s):

Henghui Zhang ◽

Yongping Xu ◽

Zhijun Zhang ◽

Jiansong You ◽

Yanyong Yang ◽

...

Keyword(s):

Escherichia Coli ◽

Protective Immunity ◽

Vaccine Candidate ◽

Pig Model ◽

Enterotoxigenic Escherichia Coli ◽

Multivalent Vaccine

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

Clinical and Vaccine Immunology ◽

10.1128/cvi.00248-16 ◽

2016 ◽

Vol 23 (7) ◽

pp. 628-637 ◽

Cited By ~ 16

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.

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Experimental Infection of Human Volunteers with the Heat-Stable Enterotoxin-Producing Enterotoxigenic Escherichia coli Strain TW11681

Pathogens ◽

10.3390/pathogens8020084 ◽

2019 ◽

Vol 8 (2) ◽

pp. 84 ◽

Cited By ~ 2

Author(s):

Sunniva Todnem Sakkestad ◽

Hans Steinsland ◽

Steinar Skrede ◽

Elisabeth Kleppa ◽

Kristine Lillebø ◽

...

Keyword(s):

Escherichia Coli ◽

T Cell ◽

Protective Efficacy ◽

T Cell Responses ◽

Enterotoxigenic Escherichia Coli ◽

Cd4 T Cell ◽

Infection Model ◽

Serological Response ◽

Cell Responses ◽

Heat Stable

Infection with enterotoxigenic Escherichia coli (ETEC) producing the heat-stable enterotoxin (ST) is one of the most important causes of childhood diarrhoea in low- and middle-income countries. Here, we undertook a controlled human infection model (CHIM) study to investigate whether ST-producing ETEC strain TW11681 would be suitable for testing the protective efficacy of new ST-based vaccine candidates in vaccine challenge models. In groups of three, nine volunteers ingested 1 × 106, 1 × 107, or 1 × 108 colony-forming units (CFU) of TW11681. Flow cytometry-based assays were used to measure CD4+ T cell responses and antibody levels targeting virulence factors expressed by the strain. We found that infection with TW11681 elicited few and mild symptoms, including mild diarrhoea in two volunteers, both of whom ingested 1 × 106 CFU. Averaged across all volunteers, the CD4+ T cell responses specific for E. coli YghJ mucinase peaked 10 days after infection (3.2-fold (p = 0.016)), while the CD4+ T cell responses specific for Colonization Factor Antigen I (CFA/I) major fimbrial subunit (CfaB) peaked after 28 days (3.6-fold (p = 0.063)). The serum CfaB-specific anti-IgA and anti-IgG/IgM levels were significantly increased and peaked 3 months after infection. Both remained elevated for the duration of the 12-month follow-up. The corresponding anti-YghJ serological response was strongest after 10 days, although a significant increase was seen only for IgA levels (3.2-fold (p = 0.008)). In conclusion, due to its low diarrhoea attack risk, TW11681 is probably not suitable for testing the efficacy of new vaccines in human challenge studies at doses 1 × 106 to 1 × 108. However, the strain may still be useful in CHIMs for studying ETEC host-pathogen interactions.

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

Infection and Immunity ◽

10.1128/iai.01304-07 ◽

2008 ◽

Vol 76 (5) ◽

pp. 2106-2112 ◽

Cited By ~ 50

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.

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Immunogenicity and protective efficacy of a recombinant adenoviral based vaccine expressing heat-stable enterotoxin (STa) and K99 adhesion antigen of enterotoxigenic Escherichia coli in mice

Molecular Immunology ◽

10.1016/j.molimm.2015.10.016 ◽

2015 ◽

Vol 68 (2) ◽

pp. 684-691 ◽

Cited By ~ 5

Author(s):

Guangcun Deng ◽

Wu Li ◽

Xiaoling Wu ◽

Shaowen Bao ◽

Jin Zeng ◽

...

Keyword(s):

Escherichia Coli ◽

Protective Efficacy ◽

Enterotoxigenic Escherichia Coli ◽

Heat Stable

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Oral administration of an anti-CfaE secretory IgA antibody protects against Enterotoxigenic Escherichia coli diarrheal disease in a non-human primate model

10.1101/748442 ◽

2019 ◽

Author(s):

Matteo Stoppato ◽

Carlos Gaspar ◽

James Regeimbal ◽

Gladys Nunez ◽

Serena Giuntini ◽

...

Keyword(s):

Escherichia Coli ◽

Oral Administration ◽

Attack Rate ◽

Protective Efficacy ◽

Enterotoxigenic Escherichia Coli ◽

Secretory Iga ◽

Primate Model ◽

Group 3 ◽

Group 2 ◽

Human Primate

ABSTACTEnterotoxigenic Escherichia coli (ETEC) is a leading cause of diarrhea-associated illness in developing countries. There is currently no vaccine licensed to prevent ETEC and the development of an efficacious prophylaxis would provide an intervention with significant impact. Recent studies suggested that effective protection could be achieved by inducing immunity to block colonization of ETEC. Here, we evaluated the efficacy of secretory (s) IgA2 and dimeric (d) IgA2 of an anti-colonization factor antigen antibody, 68-61, in the Aotus nancymaae non-human primate (NHP) ETEC challenge model via oral and parental delivery. Thirty-nine animals were distributed across 3 groups of 13, and challenged with 5.0×1011 cfu of H10407 on Day 0. Group 1 received a dIgA2 68-61 subcutaneously on day 0. Group 2 received a SIgA2 68-61 orally on days −1, 0, and +1, and Group 3 received an irrelevant SIgA2 antibody orally on days −1, 0, and +1. All animals were observed for symptoms of diarrhea, and stools were collected for ETEC colony counts. SIgA2 treatment significantly lowered the attack rate, resulting in a protective efficacy of 71.4% (p=0.025) in Group 2 as compared to Group 3. Anti-CfaE dIgA2 treatment group reduced the diarrheal attack rate, although the reduction did not reach significance (57.1%; P=0.072) as compared to the irrelevant SIgA2 Group 3. Our results demonstrated the feasibility of oral administration of SIgA as a potential immunoprophylaxis against enteric infections. To our knowledge, this is the first study to demonstrate the efficacy of administrated SIgA in a non-human primate model.

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Evaluation of the Immunogenicity and Protective Efficacy of an Enterotoxigenic Escherichia coli CFA/I Adhesin–Heat-Labile Toxin Chimera

Infection and Immunity ◽

10.1128/iai.00252-20 ◽

2020 ◽

Vol 88 (11) ◽

Author(s):

Aisling O'Dowd ◽

Milton Maciel ◽

Steven T. Poole ◽

Michael G. Jobling ◽

Julianne E. Rollenhagen ◽

...

Keyword(s):

Escherichia Coli ◽

Protective Efficacy ◽

Antibody Responses ◽

Enterotoxigenic Escherichia Coli ◽

Content Type ◽

B Subunit ◽

Colonization Factor ◽

Heat Labile ◽

Intestinal Adhesion ◽

Colonization Factors

ABSTRACT Recent efforts to develop an enterotoxigenic Escherichia coli (ETEC) vaccine have focused on the antigenically conserved tip adhesins of colonization factors. We showed previously that intranasal immunization with dsc19CfaE, a soluble variant of the in cis donor strand-complemented tip adhesin of a colonization factor of the class 5 family (CFA/I) fimbria, is highly immunogenic and protects against oral challenge with CFA/I-positive (CFA/I+) ETEC strain H10407 in the Aotus nancymaae nonhuman primate. We also reported a cholera toxin (CT)-like chimera (called dsc19CfaE-CTA2/CTB) in which the CTA1 domain of CT was replaced by dsc19CfaE that was strongly immunogenic when administered intranasally or orogastrically in mice. Here, we evaluate the immunogenicity and protective efficacy (PE) of a refined and more stable chimera comprised of a pentameric B subunit of ETEC heat-labile toxin (LTB) in lieu of the CTB pentamer and a donor strand truncation (dsc14) of CfaE. The refined chimera, dsc14CfaE-sCTA2/LTB, was highly immunogenic in mice when administered intranasally or intradermally, eliciting serum and fecal antibody responses against CfaE and LTB, as well as strong hemagglutination inhibition titers, a surrogate for neutralization of intestinal adhesion mediated by CfaE. Moreover, the chimera was safe and highly immunogenic when administered intradermally to guinea pigs. In A. nancymaae, intradermal (i.d.) immunization with chimera plus single-mutant heat-labile toxin [LT(R192G)] elicited strong serum anti-CfaE and anti-LTB antibody responses and conferred significant reduction of diarrhea compared to phosphate-buffered saline (PBS) controls (PE = 84.1%; P < 0.02). These data support the further evaluation of dsc14CfaE-sCTA2/LTB as an ETEC vaccine in humans.

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Outer Membrane Vesicles Induce Immune Responses to Virulence Proteins and Protect against Colonization by Enterotoxigenic Escherichia coli

Clinical and Vaccine Immunology ◽

10.1128/cvi.05217-11 ◽

2011 ◽

Vol 18 (11) ◽

pp. 1803-1808 ◽

Cited By ~ 46

Author(s):

Koushik Roy ◽

David J. Hamilton ◽

George P. Munson ◽

James M. Fleckenstein

Keyword(s):

Escherichia Coli ◽

Outer Membrane ◽

Protective Efficacy ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Enterotoxigenic Escherichia Coli ◽

Content Type ◽

Virulence Proteins ◽

Protective Antigens ◽

Heat Labile

ABSTRACTEnterotoxigenicEscherichia coli(ETEC) strains are a heterogeneous group of pathogens that produce heat-labile (LT) and/or heat-stable (ST) enterotoxins. Collectively, these pathogens are responsible for hundreds of thousands of deaths annually in developing countries, particularly in children under the age of 5 years. The heterogeneity of previously investigated molecular targets and the lack of complete sustained protection afforded by antitoxin immunity have impeded progress to date toward a broadly protective vaccine. Many pathogens, including ETEC, have the capacity to form outer membrane vesicles (OMV), which often contain one or more virulence proteins. Prompted by recent studies that identified several immunogenic virulence proteins in outer membrane vesicles of ETEC, we sought to examine the immunogenicity and protective efficacy of these structures in a murine model of infection. Here we demonstrate that immunization with OMV impairs ETEC colonization of the small intestine and stimulates antibodies that recognize the heat-labile toxin and two additional putative virulence proteins, the EtpA adhesin and CexE. Similar to earlier studies with EtpA, vaccination with LT alone also inhibited intestinal colonization. Together, these findings suggest that OMV could be exploited to deliver protective antigens relevant to development of ETEC vaccines.

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