FIG. 2.

Shapes of wt and pilT mutant microcolonies and morphologies of host cell microvilli. Shown are SEM images of A431 cells incubated for 3 h with medium (A), wt MS11 (B and C), or MS11pilT (D). Bacteria are color enhanced (blue) to provide added contrast with the epithelial cells (gray). (B and C) Domed and bilobed shapes of wt microcolonies. The arrowheads point to stretched and elongated microvilli beneath microcolonies. Other microvilli appear to wrap around individual diplococci at the peripheries of, or away from, microcolonies. (A) Morphology of the mock-infected cell surface. (D) Irregular shape of MS11pilT clusters and lack of microvillus remodeling. Scale bar, 10 μm.