title: Experimental enterotoxin-induced Escherichia coli diarrhea and protection induced by previous infection with bacteria of the same adhesin or enterotoxin type.
abstract: The diarrheal response to an initial and a second infection with Escherichia coli expressing various enterotoxins (the heat-stable toxin [ST] alone or in combination with the heat-labile toxin [LT]) and colonization factor antigens (CFA/I, CFA/II, or E8775-type) was studied in the reversible tie adult rabbit diarrhea model. An initial infection with high doses (1 X 10(10) to 5 X 10(11) bacteria) of the various strains regularly induced diarrhea which was usually self-limiting (only 7 of 85 animals died). The diarrheal response to equally effective doses of different strains producing both ST and LT (ST/LT) did not differ significantly with serotype or colonization factor antigen. ST/LT-producing strains appeared to induce severe disease more regularly than ST-producing strains carrying the same adhesin. Previous infection with CFA/I-carrying, ST/LT-producing E. coli protected all animals reinfected with an otherwise highly diarrheogenic dose of the same strain as well as against challenge with a CFA/I-carrying, ST/LT-producing strain with different O-, K-, and H-antigens. Fecal excretion of bacteria was also significantly reduced in the protected animals, although not completely eliminated. When only one of the two antigens, CFA/I and LT, was shared by the immunizing and rechallenge strains, partial protection was evident consistent with independent antibacterial (anti-CFA) and antitoxic (anti-LT) immune mechanisms. Oral immunization with purified CFA/I significantly reduced fluid secretion in intestinal loops infected with CFA/I-carrying enterotoxigenic bacteria.
authors.forename: C M
authors.initials: CM
authors.lastname: Ahrén
authors.forename: A M
authors.initials: AM
authors.lastname: Svennerholm
mesh_terms: D018830:Adhesins, Escherichia coli; D000268:Adhesiveness; D000818:Animals; D000942:Antigens, Bacterial / Q000276:immunology; D001426:Bacterial Proteins / Q000276:immunology; D003967:Diarrhea / Q000139:chemically induced* / Q000276:immunology / Q000382:microbiology; D004195:Disease Models, Animal; D004731:Endotoxins / Q000633:toxicity*; D004926:Escherichia coli / Q000276:immunology / Q000472:pathogenicity*; D005243:Feces / Q000382:microbiology; D005260:Female; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000276:immunology; D007114:Immunization; D008297:Male; D011817:Rabbits
chemical_list: D018830:Adhesins, Escherichia coli; D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D004731:Endotoxins; C022924:colonization factor antigens; D036781:Fimbriae Proteins