Jan Holmgren

Enterotoxin-Specific Immunoglobulin E Responses in Humans after Infection or Vaccination with Diarrhea-Causing Enteropathogens

ABSTRACT Cholera toxin (CT)-specific antibody responses of the immunoglobulin E (IgE) isotype in the sera of adult patients suffering from infection with either Vibrio cholerae O1, V. cholerae O139, or enterotoxigenic Escherichia coli(ETEC) were analyzed and compared with those in the sera of volunteers immunized with a bivalent B subunit O1/O139 whole-cell cholera vaccine. A significant IgE response to CT was observed in 90% of the patients with V. cholerae O1 infection (18 of 20; P = <0.001) and 95% of the patients with V. cholerae O139 infection (19 of 20; P = <0.001). Similarly, the majority of the patients with ETEC diarrhea (83%; 13 of 15) showed a positive IgE response to CT. Eight of 10 North American volunteers (80%) orally challenged with V. cholerae O1 showed CT-specific IgE responses (P = 0.004). In contrast, Swedish volunteers immunized with the oral cholera vaccine showed no IgE responses to CT (P value not significant). During the study period, total IgE levels in the sera of the diarrheal patients, the North American volunteers, and the Swedish cholera vaccinees alike remained unchanged. However, the total IgE levels in the sera of patients and healthy Bangladeshi controls were on average 89-fold higher than those in the sera of the healthy Swedish volunteers and 34-fold higher than those in the sera of the North American volunteers.

Monoclonal Antibodies and Immunodetection Methods for Vibrio cholerae and Escherichia coli Enterotoxins

Publisher Summary This chapter discusses the preparation of the monoclonal antibodies (MAbs) against cholera toxin (CT), and E. coli heat-labile enterotoxin (LT) of human (LTh) and porcine (LTp). Most of the MAbs produced has been directed against the B-subunit portion of the toxin molecules and were of the IgG or IgG 2 isotypes. Both MAbs against the B-subunit portion of the CT and LT had toxin-neutralizing capacity, whereas none of nine MAbs against the cholera A subunit had any detectable neutralizing ability. Of 70 anti-CT MAbs, no less than 44 reacted specifically with CT, the remaining ones showing full or partial cross-reactivity with LTs. Seven of the 25 MAbs against LTh reacted only with LTh, and five of 20 MAbs against LTp were LTp-specific. One MAb, which showed full cross-reactivity between CT, LT, and LTp, and one MAb that is specific for each of these toxins, are exploited for development of diagnostic LT detection methods based on the GM1-ELISA principle. These methods fulfilled the criteria of excellent sensitivity and specificity for the detection of any heat-labile toxin using the cross-reactive MAb, or for the detection of species-specific toxin using the unique epitope MAbs. By these methods, heat-labile enterotoxins are demonstrated in overnight cultures of fecal isolates; the sensitivity of the methods is further increased by inoculation of bacterial isolates or stools directly in GM1-coated microtiter plates.

The Binding of Bacteria Carrying CFAs and Putative CFAs to Rabbit Intestinal Brush Border Membranes

Enterotoxigenic Escherichia coli, ETEC, colonize the human intestine by means of fimbrial structures called colonization factor antigens, CFAs. On human ETEC strains three different types of CFAs have been described, i.e. the colonization factor antigens I, (CFA/I), CFA/II and CFA/IV. In addition a number of “new” putative colonization factor antigens have been identified, e.g. PCF0166, CS7, CS17 and CFA/III [M.M McConnell, this volume] although their prevalence and role in colonization have not been fully assessed.

Mucosal Immunity in the Gastrointestinal Tract in Relation to ETEC Vaccine Development

Enteric infection with enterotoxinogenic Escherichia coli (ETEC) is one of the most important causes of diarrhea in developing countries and is also the most frequent cause of diarrhea among travelers. Illness resulting from ETEC infection is characterized by watery diarrhea, often accompanied by low grade fever, abdominal cramps, malaise, and vomiting. In its most severe form ETEC infection may result in cholera-like disease leading to severe dehydration and sometimes death.

CHAPTER 61 – Engineered bacterial toxin vaccines and adjuvants

There has been remarkable progress in the understanding of the structure-function relationship of several bacterial toxins with an advanced understanding of toxin genes and the regulation of their expression. This has resulted in completely new possibilities to prepare detoxified yet immunologically active toxin derivates. Recently, engineered detoxified toxins or non-toxic subunits have also attracted much interest as vaccine carrier proteins, adjuvants, and/or inmiunomodulators, in some cases for parenteral use but especially for mucosal administration. This chapter describes the properties and clinical potential of various types of genetically engineered bacterial toxins and subunits in these different areas of vaccination, adjuvanting, and immunomodulation. Much less well appreciated than vaccination against infections, mucosal immunization may also be used to induce peripheral tolerance to prevent or suppress the development of harmful immune responses to foreign proteins derived from ingested food or from commensal microorganisms, in case these antigens would reach the body interior in an undegraded, immunogenic form. For both types of applications, it has been found that bacterial toxin derivatives can substantially influence the outcome in ways that give hope for further development toward practical medical use. Likewise, engineered bacterial toxin proteins have found a useful place as carrier proteins for various capsular polysaccharides in the development of conjugate vaccines against important infections with encapsulated bacteria.

Immune Response to Vibrio cholerae Infection in Rabbits with Special Reference to Antibodies Against in vivo Specific Antigens

In Vibrio cholerae 01 bacteria, the causative agent of cholera, changes in the in vitro environment have been found to have marked influences both on the production of cholera toxin and of cell-surface associated structures, e.g. haemagglutinins, outer membrane proteins and a toxin-coregulated pilus (TCP)1,2. We have previously shown that the intestinal milieu provide an environment in which V. cholerae 01 of both El Tor and classical biotype expresses new surface antigens, that are not found after in vitro-growth3. We have also recently shown, by studying in vivo-grown bacteria, that both TCP and a putative adhesin on El Tor vibrios, i.e. the mannose-sensitive haemagglutinin (MSHA), are expressed by V. cholerae during infection4.

Oral B Subunit-Whole Cell Vaccine Against Cholera: From Basic Research to Successful Field Trial

Cholera is an important cause of morbidity and mortality in many devel-oping countries. Cholera is also the prototype for a large group of diarrheal diseases—the “enterotoxic enteropathies”—which may be responsible for roughly half of all diarrheal disease episodes in the world. These dis¬eases are caused by various bacteria that produce one or more toxins, which by upsetting normal fluid transport processes in the gut give rise to watery diarrhea.