FIG. 5.

Representative immunofluorescence microscopic images of C. jejuni- and S. typhi-infected INT407 cells to examine bacterial association with polymerized actin. Infected host cells were prepared and immunolabeled as described in Materials and Methods, using differential fluorescence labels. In these photomicrographs, all pixels of light derived from the blue photodetector channel (actin; A and C) and green channel (bacteria; B and D) are shown in white. (A) Polymerized actin observed at 30 min postinfection in host cells infected with C. jejuni. (B) Corresponding microscopic field showing immunolabeled C. jejuni. The positions of bacteria in panel B are indicated in panel A by arrows and are not associated with areas of actin condensation. (C) Polymerized actin observed at 30 min postinfection in host cells infected with S. typhi. (D) Corresponding microscopic field showing immunolabeled S. typhi. The positions of several bacteria in panel D are indicated in panel C by arrows and are clearly associated with actin condensation. Bar markers represent 2 μm.