FIG 2.

(A) Analysis of the Caco-2 transcriptional response to infection by S. Dublin flagellated or aflagellate isolates. Caco-2 cells were infected with isolate SDu2, SDu3, SDu5, or SDu7, and at 3 h p.i., the levels of mRNA transcripts for CCL20 and IL-8 were measured by qRT-PCR. SGal is a strain of the aflagellate serovar S. Gallinarum. n/i, noninfected cells. *, statistical difference relative to noninfected cells (P < 0.05). Means and SE for two independent experiments are shown. (B) Analysis of Caco-2 transcriptional response (CCL20 expression) to infection by all S. Dublin clinical isolates. Purified S. Typhimurium flagellin (FliC) and an SDu5 derivative fliC knockout mutant (fliC::kan) were used as positive and negative controls, respectively; induction was performed for 6 h. Luciferase activity was determined and normalized to the activity obtained for the nonstimulated control (n/s), with this value considered to be 1. Means and SE for one representative experiment performed in quadruplicate are shown. Asterisks indicate significant differences relative to the nonstimulated control. *, P < 0.05; **, P < 0.01; ***, P < 0.001.