Cloning and Expression of the Genes Encoding for the Adhesive Antigens K88 and K99
More than a decade ago, enterotoxigenic E. coli strains were found to be associated with acute diarrhoea in young animals and later such strains were also found to be involved in cases of human diarrhoea. Enterotoxigenic E. coli strains release a heat labile toxin and/or a heat stable toxin which effects the fluid and electrolyte secretion in the intestine by activation of the mucosal enzymes adenyl cyclase and guanyl cyclase, respectively1,2. A number of proteinaceous surface antigens of enterotoxigenic E. coli have been identified, that are involved in the colonization of the gut by facilitating the adherence of the microorganism to the intestinal mucosa. Enterotoxins and several of these colonization factors are encoded by plasmids. The significance of organisms that possess plasmid-mediated pathogenic characteristics is that they constitute a genetic pool from which new lines of pathogenic organisms may arise. To the research worker, they represent genetic material that can be added or removed from organisms, thus permitting the construction of new lines which differ only from the parent microorganism by the presence or the absence of one character. Smith and coworkers exploited this idea to elucidate the pathogenesis of E. coli diarrhoea in animals. They showed in an elegant series of experiments that the antigens K88 and K99 promote colonization of the intestine by implanting K88 and K99 plasmids into non-pathogenic strains of E. coli or alternatively by removal of these plasmids from pathogenic strains and subsequently feeding such modified strains to neonates3,4,5.
KeywordsBrush Border Cyanogen Bromide Colonization Factor Cyanogen Bromide Fragment Colonization Factor Antigen
Unable to display preview. Download preview PDF.
- 4.H.W. Smith and M.A. Linggood, Further observations on Escherichia coli enterotoxins with particular regard to those produced by atypical piglet strains and by calf and lamb strains. The transmissible nature of these enterotoxins and of a K antigen possessed by calf and lamb strains, J.Med.Microbiol. 5: 243 (1972).PubMedCrossRefGoogle Scholar
- 14.G.E. Jones, The attachment of bacteria to the surfaces of animal cells. In Microbial Interactions, Receptors and recognition, Series B, Vol. 3 (J.L. Riessig, Ed.). Chapman and Hall, London, pp. 139–176 (1977).Google Scholar
- 17.P.A.M. Guinée, J. Veldkamp and W.H. Jansen, Improved Minca medium for the detection of K99 antigen in calf enterotoxigenic strains of Escherichia coli, Infec.Immun. 15: 676 (1977).Google Scholar
- 26.R. Schmitt, R. Mattes, K. Schmid and J. Altenburger, Raf plasmids in strains of Escherichia coli and their possible role in entero-pathogenicity. In: Plasmids of Medical, environmental and commercial importance (K.N. Timmis and A. Punier, Eds.) Elsevier Amsterdam, pp. 199–210 (1979).Google Scholar