The expression of nonagglutinating fimbriae and its role inProteus mirabilisadherence to epithelial cells

Abstract

Proteus mirabilis is a common causative agent of human urinary tract infections, especially in catheterized patients and in those patients with structural abnormalities of the urinary tract. In addition to the production of hemolysin and urease, fimbriae-mediated adherence to uroepithelial cells and kidney epithelium may be essential for virulence of P. mirabilis. A single P. mirabilis strain is capable of expressing several morphologically distinct fimbrial species, which can each be favoured by specific in vitro growth conditions. The fimbrial species reported to date include mannose-resistant/Proteus-like fimbriae, ambient temperature fimbriae, P. mirabilis fimbriae, and nonagglutinating fimbriae (NAF). Here, using intact bacteria or purified NAF as immunogens, we have generated the first reported NAF-specific monoclonal antibodies (mAbs). Bacteria expressing NAF as their only fimbrial species adhered strongly to a number of cell lines in vitro, including uroepithelial cell lines. Binding of P. mirabilis was markedly reduced following preincubation with NAF-specific mAbs and Fab fragments. The presence of NAF with highly conserved N-terminal sequences on all P. mirabilis strains so far examined, combined with the ability of both anti-NAF mAbs and purified NAF molecules to inhibit P. mirabilis adherence in vitro, suggests that NAF may contribute to the pathogenesis of P. mirabilis.

Proteus mirabilis fimbriae (PMF) are important for both bladder and kidney colonization in mice

“…no. 85061107) (Tolson et al, 1997). For the adherence assay, bacteria from an 18 h culture at 37 uC on LB agar were inoculated into 5 ml of LB broth and grown statically at 37 uC for 48 h. Then, bacteria were harvested and resuspended in McCoy's 5a supplemented with 2 mM glutamine and 10 % (v/v) fetal calf serum to 2610 8 c.f.u.…”

Complicated Catheter-Associated Urinary Tract Infections Due toEscherichia coliandProteus mirabilis

“…The N-terminal sequence of this fimbrial subunit was confirmed to be identical to the N-terminal sequence from P. mirabilis strain HU1069 of the study reported by Wray et al and not homologous to the N termini of MR/P, ATF, or PMF fimbrial subunits (406). Bacteria expressing NAF adhered strongly to a number of cell lines in vitro, including uroepithelial cells (407) and MDCK (Madin-Darby canine kidney) (5,216) and EJ/28 urinary tract tumor (214) cell lines. Purified NAF from P. mirabilis binds to a number of glycolipids such as asialo-GM1, asialo-GM2, and lactosyl ceramide, as demonstrated by thin-layer chromatography overlay assays and solidphase binding assays (216).…”

The binding ofProteus mirabilisnonagglutinating fimbriae to ganglio-series asialoglycolipids and lactosyl ceramide

“…We have previously demonstrated that an anti-NAF mAb, NAF.31, was capable of inhibiting P. mirabilis binding to a number of epithelial cell lines (Tolson et al 1997). It was of interest to see if this antibody is also effective in inhibiting NAF binding to the glycolipid receptors.…”

“…Microtiter wells were coated with LacCer, asialo-GM2, or asialo-GM1 (1 µg per well), and blocked as described above. Anti-P. mirabilis NAF monoclonal antibodies, NAF.31, generated in our laboratory (Tolson et al 1997), were employed in these assays. Purified NAF.31 mAb was premixed with Bt-NAF in PBS containing 1% BSA, and incubated for 30 min prior to addition to precoated wells.…”

“…We have been interested in understanding the adherence mechanism of P. mirabilis and have previously demonstrated the role of NAF in mediating P. mirabilis adherence to epithelial cells. Furthermore, we have shown that anti-NAF antibodies block bacterial adhesion in vitro (Tolson et al 1997;Latta et al 1998).…”