FIG. 3.
Time course of cytokine mRNA expression in HeLa cells after Y. enterocolitica infection. HeLa cells were infected for 1 h with Y. enterocolitica pYV− at an MOI of ∼150 bacteria/cell. After 1 h of infection, bacteria were removed from the cultures by washing with PBS and further incubated in the presence of gentamicin for 5 h. Uninfected cells as controls received the same treatment without bacterial infection. Data shown are from a representative experiment with triplicate samples. Comparable results were obtained in additional experiments. (A) Qualitative RT-PCR analysis. (B) Semiquantitative mRNA levels determined by digitally scanning the bands and calculating intensity of each cytokine band by a fluoroimager. Values are expressed in arbitrary units as ratio of the cytokine mRNA level to the corresponding β-actin mRNA level (means of triplicate samples ± standard deviation, interpolated curves). The points of time of half-maximum cytokine expression (tmax/2) are indicated.