Family of Escherichia coli Dr adhesins: decay-accelerating factor receptor recognition and invasiveness.

In 1984, Väisänen-Rhen [1] and Labigne-Roussel et al. [2] described a novel Escherichia coli adhesin of unknown receptor specificity. Due to its association with uropathogenic strains of serotype O75 and because of the unknown receptor, the adhesin was named O75X [1]. Between 1984 and 1989, 3 groups independently cloned novel adhesins that were later found to have very similar genetic organization: The clones were Dr (cloned by Nowicki et al. [3]), afimbrial adhesins (Afa)-I and Afa-III (cloned by Labigne-Roussel and colleagues [2, 4]), and F1845 (cloned by Bilge et al. [5]). In 1990, Nowicki et al. [6] provided evidence that the novel adhesins, including O75X, recognize a common receptor, Dr (a) blood group antigen. Dr (a) blood antigen was later localized to the key complement regulatory molecule, decay-accelerating factor ([DAF]; CD55), which protects tissues from damage by autologous complement attack. Most uropathogenic adhesins traditionally were named after the receptor they recognized; hence, we proposed to rename O75X the “Dr adhesin,” with the remaining adhesins to be included in the Dr family of E. coli adhesins. In the 1990s, various investigators described several adhesins that were cloned from E. coli of human and animal origin and that display similar genetic organization and/or DAF receptor recognition. Of interest, most of the tested adhesins appeared to have invasive capacity, with probably at least two genes contributing to the internalization process [7, 8]. We therefore propose that the prototypes and the new related adhesins constitute members of the Dr family of adhesins (table 1).