Hyaluronic-Acid Mediated Adhesion of Pasteurella multocida to HeLa Cells

Adhesion of bacteria to host cells is a crucial step in colonisation and disease pathogenesis. In this connection, further studies were conducted to analyse the attachment mechanisms of Pasteurella multocida to HeLa cells. Of 10 strains of P. multocida, belonging to serotypes A, B, D and E, all six of serotype A strains adhered strongly to HeLa cells. Exposure of the six strains to several physical, chemical and enzymatic protein-denaturating treatments did not affect adhesion. However, treatment of the bacteria with hyaluronidase clearly reduced their adhesive capacities. Pre-treatment of the He La cells with hyaluronic acid, or with extracts of the adherent pasteurellae containing hyaluronic acid, also reduced adhesion. Thus, it could be suggested that adhesion of the six P. multocida A strains was mediated by capsular hyaluronic acid. IN the process of infection, bacterial adhesion to host cells is significant in the pathogenesis of disease. This research, on the adhesive capacity of Pasteurella multocida, was stimulated by a report of Glorioso et al. (1982) on adhesion of P. multocida serotype A (Carter) to HeLa cells. Materials and Methods Pasteurella multocida strains The 10 strains of P. multocida used in this study (Table 1) were cultured overnight at 37°C in brainheart infusion (BHI) (Gibco, Eggenstein, FRG). Then the bacteria were centrifuged at 11 000 x g and the pellets were re-suspended in HANKS balanced salt solution (HBSS) (Sigma, Deisenhofen, FRG) and adjusted to an optical density of 1.0 at 620 nm. The suspensions were stained with fluoresceine isothiocyanate at pH 7.4 (Valentin-W eigand et al. 1987).