Effects of <i>espA</i> and <i>csgA</i> deletions on O157 adherence to HEp-2 cells and expression of EspA and CsgA.

<p><b>(A)</b> Micrographs showing adherent bacteria on HEp-2 cells (indicated by black arrows) of Parent (1), Δ<i>hha</i> (2), Δ<i>hha</i> Δ<i>csgA</i> (3), <i>csgA</i>⁺/Δ<i>hha</i> Δ<i>csgA</i> (4), Δ<i>hha</i> Δ<i>espA</i> (5), <i>espA</i>⁺/Δ<i>hha</i> Δ<i>espA</i> (6), Δ<i>hha</i> Δ<i>csgA</i> Δ<i>espA</i> (7), <i>espA</i>⁺/Δ<i>hha</i> Δ<i>csgA</i> Δ<i>espA</i> (8), <i>csgA</i>⁺/Δ<i>hha</i> Δ<i>csgA</i> Δ<i>espA</i> (9) mutant strains. <b>(B)</b> A bar graph showing the percent of adherent bacteria on HEp-2 cells computed by dividing the number of adherent bacterial cells by the sum of non-adherent and adherent bacteria. Bars indicate average of three independent assays and error bars represent standard deviation of 2. The * above the bars indicates <i>p</i> < 0.05 when Δ<i>hha</i> mutant was compared to the parent and the double and triple mutants were compared to the Δ<i>hha</i> mutant strains. <b>(C)</b> Western blot analysis of cell lysates (prepared by growing bacterial strains in DMEM at 37°C to an OD₆₀₀ of 0.8 to 1.0) using anti-DnaK (top blot), anti-EspA (middle blot), and anti-CsgA (bottom blot) antibodies. Molecular weights of protein standards (Lane M) are indicated in kD on right side of each blot. The locations of predicted or identified DnaK, EspA, and CsgA proteina are indicated on the left. Lanes numbered 1 through 9 contains cell lysates of strains listed in the same order as in Fig 2A.