Diffuse Adherence Of Enteropathogenic Escherichia coli Strains

Abstract

The adherence of enteropathogenic Escherichia coli (EPEC) to the small bowel mucosa is an important step in the pathogenesis of diarrhoeal diseases. Two distinct patterns of adherence have been reported for EPEC bacteria in tissue culture employing HeLa- or HEp-2-cells as model systems: localized (LA) and diffuse (DA) adherence. To study adhesins responsible for DA we used EPEC-strains isolated from cases of infantile diarrhoea in Germany and Brazil. In all EPEC strains investigated so far, the DA-factor has been found to be plasmid encoded. The adhesin gene of strain 2787 was cloned into pBR322. The gene is localized on a plasmid of about 100 kb. The recombinant plasmid pIB6 conferred the binding activity of the wild-type strain on E. coli K-12 strains. By deletion analysis a 6.0 kb fragment was shown to be sufficient for expression of the DA phenotype. The adhesin, designated AIDA-I, was purified by heat-shock extraction of the wildtype isolate as well as the recombinant strain. AIDA-I was shown to adhere specifically to HeLa-cells and adhesion of C600(pIB6) could be inhibited by antiserum.