INHIBITION OF ENTEROPATHOGENIC ESCHERICHIA-COLI ADHERENCE TO HELA-CELLS BY IMMUNE RABBIT SERA

We have studied the effect of immune rabbit sera on the localized (LA) and diffuse (DA) adherence to HeLa cells of 10 enteropathogenic Escherichia coli (EPEC) strains belonging to serogroups 055, 086, O111, 0 1 19, and 0142. Anti-La 1 serum, obtained by rabbit immunization with an E. coli strain harboring a cloned DNA fragment from an EPEC LA plasmid, strongly inhibited the adherence of all serogroups but one (O142). Similar results were obtained with anti-LA2 serum, which is anti-O111 serum absorbed with a non-adherent 0111:H- EPEC strain. In contrast, non-absorbed anti-055 and anti-O111 sera showed an inhibitory effect mainly on the adherence of homologous strains. Except for one experiment diffuse adherence was not inhibited by any antiserum used. The inhibitory effect of immune sera on localized adherence does not seem to be correlated with plasmid curing since adherence plasmid pMS49 proved to be stable after treatment with anti-055 and anti-O111 sera. The cross-inhibition of adherence by anti-LA sera suggests that localized adherence-related adhesins of the 055, 086, 0111, and 0119 strains share similar antigens.