Adherence of Ureaplasma urealyticum to human epithelial cells

Adherence of Ureaplasma urealyticum cells to eukaryotic cell monolayers was quantified using the Bertholet assay to monitor ammonia produced from urea by ureaplasma urease. Adherence was abolished by pre-treatment of ureaplasmas with HeLa cell extracts and inhibited to varying degrees by pretreatment of the ureaplasmas with N-acetylneuraminic acid, specific antisera and monoclonal antibodies. The data suggest the presence of several ureaplasma adhesins, some of which are species- or serotype-specific and some of which are proteinaceous and antigenic. The serotype-8-specific 96 kDa surface-expressed antigen may be one adhesin. Pre-treatment of HeLa cell monolayers with neuraminidase significantly reduced ureaplasma adherence and, using a novel 'immunoblot adherence assay', ureaplasmas were shown to bind to a number of HeLa cell components, three of which appear to terminate in sialic acid.