FIG. 1.

Adhesion and cytotoxicity of the KIM5 Δ5 mutant complemented with various Y. pestis adhesins. (A) Giemsa-stained infection assays at 2 h postinoculation. Cell rounding and bound bacteria are visible. Pictures are representative of overall effects. (B) Cell rounding/cytotoxicity assay of KIM5 derivatives, visualized by phase-contrast microscopy. HEp-2 cells were infected, and cell rounding was observed at hours 2, 4, and 8. (C) Quantification of cell rounding data from panel B at various time points (5 fields/strain; n, ∼500 cells). As a negative control, a KIM5 strain cured of the Yop-encoding virulence plasmid, pCD1, was included. *, P < 0.05; **, P < 0.000001. Error bars represent standard deviations.