A Novel Group of Moraxella catarrhalis UspA Proteins Mediates Cellular Adhesion via CEACAMs and Vitronectin
Figure 8
Adherence of the Mx strains expressing CEACAM-binding variant UspA2 proteins to CEACAM1 expressed on A549 human lung epithelial cells.
A549 cells were pretreated with IFN-γ for 24 h prior to infection previously shown to upregulate CEACAM1 expression [34]. Cells were infected with 035E Hag-, Hag- derivative of 035E D2 and clinical isolates MX1, S36:1 and S43:4 at an MOI of 100 for 1 hr at RT in medium 199 without serum. Infections were performed without (column 1), or with A0115 (anti-CEACAM binding polyclonal antibody; column 2). Following infection, monolayers were fixed, blocked, and incubated with antisera as described in experimental procedures and rhodamine conjugated secondary antibodies. As can be seen in the right columns, a dramatic reduction in Mx binding in the presence of A0115 occurred in all cases except the Hag- mutant of the 035E parental strain which lacks CEACAM-binding properties. Antibodies not directed against the N-domain of CEACAMs fail to inhibit the interaction of Mx with A549 cells (not shown here; [12]). Data are representative of duplicate infections performed on at least two separate occasions. Scale bar is 20 µm.