Cross-reactivity and avidity of antibody responses induced in humans by the oral inactivated multivalent enterotoxigenic Escherichia coli (ETEC) vaccine ETVAX

ABSTRACT The complete coding cDNA of HSP60 from Paracoccidioides brasiliensis was overexpressed in an Escherichia coli host to produce high levels of recombinant protein. The protein was purified by affinity chromatography. A total of 169 human serum samples were tested for reactivity by Western blot analysis with the purified HSP60 recombinant protein. Immunoblots indicated that the recombinant P. brasiliensis HSP60 was recognized by antibodies in 72 of 75 sera from paracoccidioidomycosis patients. No cross-reactivity was detected with individual sera from patients with aspergillosis, sporotrichosis, cryptococcosis, and tuberculosis. Reactivity to HSP60 was observed in sera from 9.52% of control healthy individuals and 11.5% of patients with histoplasmosis. The high sensitivity and specificity (97.3 and 92.5%, respectively) for HSP60 suggested that the recombinant protein can be used singly or in association with other recombinant antigens to detect antibody responses in P. brasiliensis-infected patients.

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Heat-Stable Enterotoxin of Enterotoxigenic Escherichia coli as a Vaccine Target

Infection and Immunity ◽

10.1128/iai.01397-09 ◽

2010 ◽

Vol 78 (5) ◽

pp. 1824-1831 ◽

Cited By ~ 60

Author(s):

Arne Taxt ◽

Rein Aasland ◽

Halvor Sommerfelt ◽

James Nataro ◽

Pål Puntervoll

Keyword(s):

Escherichia Coli ◽

Vaccine Development ◽

Severe Disease ◽

Epidemiological Data ◽

Structural Similarity ◽

Biological Properties ◽

Cross Reactivity ◽

Enterotoxigenic Escherichia Coli ◽

Natural Form ◽

Heat Stable

ABSTRACT Enterotoxigenic Escherichia coli (ETEC) is responsible for 280 million to 400 million episodes of diarrhea and about 380,000 deaths annually. Epidemiological data suggest that ETEC strains which secrete heat-stable toxin (ST), alone or in combination with heat-labile toxin (LT), induce the most severe disease among children in developing countries. This makes ST an attractive target for inclusion in an ETEC vaccine. ST is released upon colonization of the small intestine and activates the guanylate cyclase C receptor, causing profuse diarrhea. To generate a successful toxoid, ST must be made immunogenic and nontoxic. Due to its small size, ST is nonimmunogenic in its natural form but becomes immunogenic when coupled to an appropriate large-molecular-weight carrier. This has been successfully achieved with several carriers, using either chemical conjugation or recombinant fusion techniques. Coupling of ST to a carrier may reduce toxicity, but further reduction by mutagenesis is desired to obtain a safe vaccine. More than 30 ST mutants with effects on toxicity have been reported. Some of these mutants, however, have lost the ability to elicit neutralizing immune responses to the native toxin. Due to the small size of ST, separating toxicity from antigenicity is a particular challenge that must be met. Another obstacle to vaccine development is possible cross-reactivity between anti-ST antibodies and the endogenous ligands guanylin and uroguanylin, caused by structural similarity to ST. Here we review the molecular and biological properties of ST and discuss strategies for developing an ETEC vaccine that incorporates immunogenic and nontoxic derivatives of the ST toxin.

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Antibody Responses in Humans against Coli Surface Antigen 6 of Enterotoxigenic Escherichia coli

Infection and Immunity ◽

10.1128/iai.66.9.4507-4510.1998 ◽

1998 ◽

Vol 66 (9) ◽

pp. 4507-4510 ◽

Cited By ~ 10

Author(s):

Anna Helander ◽

Christine Wennerås ◽

Firdausi Qadri ◽

Ann-Mari Svennerholm

Keyword(s):

Escherichia Coli ◽

Surface Antigen ◽

Immunoglobulin A ◽

Antibody Responses ◽

Enterotoxigenic Escherichia Coli ◽

Specific Immunoglobulin

ABSTRACT Enterotoxigenic Escherichia coli (ETEC) strains expressing only coli surface antigen 6 (CS6) have previously been isolated from patients with diarrhea, but the immunogenicity of CS6 has not been established in humans. We have detected CS6-specific immunoglobulin A responses in the feces and blood of patients convalescing from natural ETEC disease and of volunteers given an oral ETEC vaccine.

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

Infection and Immunity ◽

10.1128/iai.00099-19 ◽

2019 ◽

Vol 87 (7) ◽

Cited By ~ 5

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.

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Characterization of Immunological Cross-Reactivity between Enterotoxigenic Escherichia coli Heat-Stable Toxin and Human Guanylin and Uroguanylin

Infection and Immunity ◽

10.1128/iai.01749-14 ◽

2014 ◽

Vol 82 (7) ◽

pp. 2913-2922 ◽

Cited By ~ 14

Author(s):

Arne M. Taxt ◽

Yuleima Diaz ◽

Amélie Bacle ◽

Cédric Grauffel ◽

Nathalie Reuter ◽

...

Keyword(s):

Escherichia Coli ◽

Diarrheal Disease ◽

Cross Reactivity ◽

Enterotoxigenic Escherichia Coli ◽

Middle Income ◽

Content Type ◽

Cross Reactions ◽

Endogenous Peptides ◽

Heat Stable ◽

Wide Range

ABSTRACTEnterotoxigenicEscherichia coli(ETEC) expressing the heat-stable toxin (ST) (human-type [STh] and porcine-type [STp] variants) is among the five most important enteric pathogens in young children living in low- and middle-income countries. ST mediates diarrheal disease through activation of the guanylate cyclase C (GC-C) receptor and is an attractive vaccine target with the potential to confer protection against a wide range of ETEC strains. However, immunological cross-reactivity to the endogenous GC-C ligands guanylin and uroguanylin is a major concern because of the similarities to ST in amino acid sequence, structure, and function. We have investigated the presence of similar epitopes on STh, STp, guanylin, and uroguanylin by analyzing these peptides in eight distinct competitive enzyme-linked immunosorbent assays (ELISAs). A fraction (27%) of a polyclonal anti-STh antibody and an anti-STh monoclonal antibody (MAb) cross-reacted with uroguanylin, the latter with a 73-fold-lower affinity. In contrast, none of the antibodies raised against STp, one polyclonal antibody and three MAbs, cross-reacted with the endogenous peptides. Antibodies raised against guanylin and uroguanylin showed partial cross-reactivity with the ST peptides. Our results demonstrate, for the first time, that immunological cross-reactions between ST and the endogenous peptides can occur. However, the partial nature and low affinity of the observed cross-reactions suggest that the risk of adverse effects from a future ST vaccine may be low. Furthermore, our results suggest that this risk may be reduced or eliminated by basing an ST immunogen on STp or a selectively mutated variant of STh.

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Infection with colonization factor antigen I-expressing enterotoxigenic Escherichia coli boosts antibody responses against heterologous colonization factors in primed subjects

Epidemiology and Infection ◽

10.1017/s0950268897008200 ◽

1997 ◽

Vol 119 (3) ◽

pp. 391-393 ◽

Cited By ~ 11

Author(s):

A. RUDIN ◽

G. WIKLUND ◽

C. WENNERÅS ◽

F. QADRI

Keyword(s):

Escherichia Coli ◽

Antibody Responses ◽

Enterotoxigenic Escherichia Coli ◽

Enzyme Linked Immunosorbent Assay ◽

Symptomatic Infection ◽

Colonization Factor ◽

Serum Iga ◽

Iga Antibody ◽

Colonization Factors ◽

Colonization Factor Antigen I

Enterotoxigenic Escherichia coli (ETEC) adhere to the intestinal mucosa by a number of fimbrial colonization factors (CFs) that have been claimed to induce only type-specific immunity. However, adult Bangladeshi patients infected with CFA/I-expressing bacteria, developed significant plasma IgA antibody responses, as determined by enzyme-linked immunosorbent assay, not only against the homologous fimbriae but also against several heterologous CFs, i.e. CS1, CS2, CS4 and PCFO166 fimbriae. In contrast, North American volunteers, who had probably not been infected by ETEC previously, responded with serum IgA against CFA/I fimbriae but not against any other CFs after symptomatic infection with CFA/I-expressing ETEC. Thus, infection with CFA/I-expressing bacteria may boost immune responses against CFs with a related amino acid sequence in previously primed subjects.

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