title: Assessing the expression of enterotoxigenic Escherichia coli-specific surface antigens in recombinant strains by transmission electron microscopy and immunolabeling.
abstract: Infections with enterotoxigenic Escherichia coli (ETEC) are a major cause of travelers' diarrhea worldwide. Colonization of the small intestine mucosa is dependent on specific colonization factor antigens (CFA) and coli surface (CS) antigens. CFA/1, CS3, and CS6 are the most prevalent fimbrial antigens found in clinical isolates. The goal of our study was to visualize the morphology of CS3 and CS6 fimbriae in wild-type and recombinant E. coli strains by means of transmission electron microscopy in conjunction with negative staining and immunolabeling. Corresponding ETEC genes were cloned into E. coli K12 strain DH10B. Expression of fimbriae was dependent on culture conditions and sample handling. Specific immunolabeling of fimbriae unequivocally demonstrated the presence of all types of surface antigens investigated. Negative staining was effective in revealing CS3 but not CS6. In addition, this technique clearly demonstrated differences in the morphology of genetically and immunologically identical CS3 surface antigens in wild-type and recombinant strains. This paper provides a basis for the assessment of recombinant vaccines.
authors.affiliation: Division of Veterinary Anatomy, University of Berne Veterinary School, CH-3001 Bern, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Lüdi
authors.forename: Joachim
authors.initials: J
authors.lastname: Frey
authors.forename: Didier
authors.initials: D
authors.lastname: Favre
authors.forename: Michael H
authors.initials: MH
authors.lastname: Stoffel
mesh_terms: D000942:Antigens, Bacterial / Q000096:biosynthesis*; D004768:Enterotoxins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000378:metabolism*; D048168:Escherichia coli K12 / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000096:biosynthesis*; D036781:Fimbriae Proteins / Q000096:biosynthesis*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D007150:Immunohistochemistry; D046529:Microscopy, Electron, Transmission; D011995:Recombination, Genetic
chemical_list: D000942:Antigens, Bacterial; C098406:CS6 antigen, E coli; D004768:Enterotoxins; D029968:Escherichia coli Proteins; C081391:nfaE protein, E coli; D036781:Fimbriae Proteins