Contribution of BspA, BspB and BspF to inhibition of host cell secretion during infection.

<p>(A) SEAP secretion in HeLa cells infected with either wild type or <i>bsp</i> in-frame deletion mutants. Brefeldin A (BFA) treatment (5 µg/ml) was used as a control for secretion inhibition. (B) SEAP secretion in HeLa cells infected with either <i>B. abortus</i> 2308, Δ<i>bspB</i> and Δ<i>bspF</i> or the chromosomally-complemented strains Δ<i>bspB</i>::<i>mTn7-bspB</i> or Δ<i>bspF</i>::<i>mTn7-bspF</i>. (C) SEAP secretion in HeLa cells infected with either <i>B. abortus</i> 2308, Δ<i>virB9</i>, Δ<i>bspA</i>, Δ<i>bspB</i>, Δ<i>bspF</i>, the chromosomally-complemented strains Δ<i>bspB</i>::<i>mTn7-bspB</i> or Δ<i>bspF</i>::<i>mTn7-bspF</i> or the Δ<i>bspABF</i> mutant. (D) SEAP secretion in HeLa cells infected with either <i>B. abortus</i> 2308, its isogenic Δ<i>bspA</i>, Δ<i>bspB</i>, Δ<i>bspF</i>, Δ<i>bspD</i>, Δ<i>bspE</i> mutants, or 2308 carrying pJC123, pJC124 or derivatives expressing FLAG-tagged BspA, BspB, BspF, BspD or BspE. Infection assays were carried out as described in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1003556#s4" target="_blank">Materials and Methods</a> section and SEAP secretion was measured at 6 h post-synchronization, corresponding to 30 h pi (A, B and D) or 8 h pi (C). Data points represent the means ± SD from three independent experiments performed in quadruplicates. Statistically significant differences (P<0.05) are indicated by asterisks, as compared to control (C) or 2308 (D) samples.