Fig 1.

(A) Expression of TLR2 and TLR1 was determined by reverse transcription-PCR (RT-PCR) on RNA extracted from HeLa cells transfected with an empty vector or a TLR2 or TLR1 expression vector as well as from T84 cells. (B) Invasion of polarized T-84 epithelial cells by wild-type S. Typhimurium and its isogenic csgBA mutant. Bacteria were grown under conditions optimal for expression of curli fibrils (bars A) or optimal for expression of the T3SS-1 (bars B) prior to inoculation of cells. The number of bacteria recovered from the gentamicin protection assay is expressed as the percentage of the number present in the inoculum. Data are shown as geometric means from three independent experiments ± standard deviation. (C) IL-8 secretion in the supernatants of polarized T-84 cells infected with wild-type S. Typhimurium and its isogenic csgBA mutant was determined after 24 h by ELISA. Significant statistical differences are indicated above the bars (P < 0.05). n.s., not significant.