FIG. 6.

O antigen-expressing Y. pestis loses the ability to invade DCs and HeLa-DC-SIGN cells. Y. pestis KIM (rough)/Y. pestis KIM-6/pAY100.1 (smooth) were tested for the ability to invade DCs (A) and HeLa-DC-SIGN cells (B). E. coli K-12 CS1861 (smooth)/CS180 (rough) were used as controls. The same methods described in the legends to Fig. 2 and 3 were applied in these experiments. *, P < 0.001 by Student's t test comparing the interaction of DCs (A) and HeLa-DC-SIGN cells (B) with Y. pestis KIM-6 (rough) to interaction with Y. pestis KIM-6/pAY100.1 (smooth). n was nine samples for each test. The error bars indicate standard errors.