FIG. 1.

Cytokine mRNA production of HeLa cells after Y. enterocolitica infection. (A) HeLa cells were infected with Y. enterocolitica (Y.e.) pYV⁻ or inv mutant strain, E. coli (E.c.), or E. coli(pInv1914) expressing Y. enterocolitica inv (MOI of ∼150 bacteria/cell). After 1 h, gentamicin (100 μg/ml) was added to kill extracellular bacteria. Uninfected cells as controls received the same treatment without bacterial infection. After an additional 2 h, total cellular RNA was extracted from cells. PCR products were fractionated on a 3% agarose gel stained with ethidium bromide. (B) Bacterial invasion was inhibited by treating HeLa cells with wortmannin (100 ng/ml) 20 min prior to infection. Data shown are from a representative experiment with duplicate samples. Comparable results were obtained in additional experiments.