Immunoprotection against enterotoxigenic diarrhea in rabbits by peroral administration of purified colonization factor antigen I (CFA/I)

Immunoprotective oral whole cell vaccine for enterotoxigenic Escherichia coli diarrhea prepared by in situ destruction of chromosomal and plasmid DNA with colicin E2

“…Our previous experiments, in which purified CFA/I fimbriae were administered orally to adult rabbits [16,17] or to human volunteers ]12], supported the hypothesis that protection against challenge with virulent ETEC could be achieved by stimulating a good CFA-specific intestinal secretory IgA response. This idea has gained further support from the results of experiments in which a non-toxigenic CFA/II-positive candidate vaccine strain (serotype 06 : H16, possessing antigens CS1 and CS3) afforded significant protection against challenge with an enterotoxigenic strain possessing the same CFA/II fimbrial antigens, but a different serotype [18].…”

“…Various strategies have been employed in attempts to develop vaccines against bacterial enteropathogens such as Shigella, Salmonella, V. cholerae and ETEC, and various degrees of success have been achieved. The approaches differ primarily in the form of antigen chosen for oral administration; i.e., living attenuated strains [5,[9][10][11], whole bacteria killed by either heat and/or chemicals [28,29], purified toxoids to provoke anti-toxin immunity [7,13,14] and purified fimbrial CFAs to provoke immunity against intestinal colonization [12,[16][17]. Candidate vaccines have been designed for each pathogen mainly on the basis of recognized mechanisms of pathogenesis, antigenicity of killed cell preparations or purified virulence factors, and in consideration of the risk of minor but undesirable responses to living attenuated strains.…”

Non-replicating oral whole cell vaccine protective against enterotoxigenic Escherichia coli (ETEC) diarrhea: Stimulation of anti-CFA (CFA/I) and anti-enterotoxin (anti-LT) intestinal IgA and protection against challenge with ETEC belonging to heterologous serotypes

“…There is good evidence that natural immunity against these pathogens involves intestinal secretory IgA antibody stimulated by exposure of the gut to a multiplicity of bacterial antigens, examples of which include (a) surface-associated antigens such as heat-stable somatic antigens, outer membrane proteins and fimbriae such as the colonization factor antigens (CFAs) of the ETEC [1,2,[6][7][8] and (b) secreted virulence factors such as cholera enterotoxin and the heat-labile enterotoxin (LT) of the ETEC [9][10][11]15]. Promising results have been obtained with experimental oral vaccine preparations consisting of living attenuated strains of bacteria ]6,7,12], killed cell preparations [1,5] and cell-free virulence factors such as the cholera toxin B subunit [5], ETEC heat-stable enterotoxin rendered antigenic [13], and CFA/I [4,14,15].…”

Coli surface antigens 1 and 3 of colonization factor antigen II-positive enterotoxigenic Escherichia coli: morphology, purification, and immune responses in humans

“…Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea in infants in less-developed countries (2), in travelers (43), and in infant herd animals (59). The recognition that special classes of protein fimbriae (also called pili) mediate the attachment of ETEC to receptors on the intestinal mucosa has provided one feasible approach to immunization (1,10,12,26,27,32,33,35,44,47,53; M. M. Levine, R. E. Black, M. L. Clements, C. R. Young, E. Boedeker, C. Cheney, P. Schadl, and H. Collins in E. C. Boedeker, ed., Attachment of Micro Organisms to the Gut Mucosa, in press). Such vaccines stimulate antibodies against the fimbrial antigens, thereby preventing the ETEC strains from attaching to and colonizing the mucosa of the small intestine.…”