The redundant role of SipA and SopE₂ for enterocyte invasion.

<p><b>(A-C)</b> 1-day-old C57BL/6 mice were orally infected with 100 CFU wild type (WT) (filled circles) or isogenic <i>sopE</i>_<i>2</i><i>sipA</i> mutant <i>S</i>. Typhimurium (filled triangles). Viable counts in <b>(A)</b> isolated gentamicin-treated enterocytes and <b>(B)</b> total liver tissue homogenate at 4 days p.i.. <b>(C)</b> Quantitative RT-PCR for <i>Cxcl2</i> mRNA in total RNA prepared from enterocytes isolated at 4 days p.i.. Values were normalized to uninfected age-matched control animals (crosses). Individual values and the mean from at least two independent experiments are shown (n = 4–6 animals per group). The data for uninfected control animals and WT <i>Salmonella</i> infected mice are identical to <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1006925#ppat.1006925.g001" target="_blank">Fig 1A–1C</a>. <b>(D-F)</b> 1-day-old C57BL/6 mice were orally infected with 100 CFU WT (filled circles), isogenic <i>sipA</i> mutant (open squares), complemented Δ<i>sipA</i> p<i>sipA</i> (filled squares), isogenic <i>sopE</i>_<i>2</i> mutant (open diamonds), or complemented Δ<i>sopE</i>_<i>2</i> p<i>sopE</i>_<i>2</i> (filled diamonds) <i>Salmonella</i>. Viable counts in <b>(D)</b> isolated gentamicin-treated enterocytes and <b>(E)</b> total liver tissue homogenate at 4 days p.i.. <b>(F)</b> Quantitative RT-PCR for <i>Cxcl2</i> mRNA in total RNA prepared from enterocytes isolated at 4 days p.i.. Values were normalized to uninfected age-matched control animals (crosses). Individual values and the mean from at least two independent experiments are shown (n = 3–5 animals per group). The data for uninfected control animals and <i>Salmonella</i> WT infected mice are identical to <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1006925#ppat.1006925.g001" target="_blank">Fig 1A–1C</a>. <b>(G)</b> Immunostaining for <i>S</i>. Typhimurium (red) in small intestinal tissue sections at 4 days p.i. with 100 CFU Δ<i>sopE</i>_<i>2</i><i>sipA</i>, Δ<i>sipA</i>, or Δs<i>opE</i>_<i>2</i> <i>S</i>. Typhimurium <i>Salmonella</i>. Counterstaining with E-cadherin (green), WGA (white) and DAPI (blue). Bar, 5 μm. <b>(H)</b> Co-immunostaining for <i>Salmonella</i> Δ<i>sipA</i>, Δ<i>sopE</i>_<i>2</i> (green) and LAMP1 (red) in small intestinal tissue sections at day 4 p.i.. Counterstaining with E-cadherin (white) and DAPI (blue). Bar, 5 μm. <b>(I)</b> Quantitative evaluation of the percentage of intraepithelial <i>S</i>. Typhimurium associated with LAMP1 staining. All microcolonies from three tissue sections per infected neonate were analyzed (n = 5) at day 4 p.i.. Results represent the mean ± SD. <b>(J)</b> Co-immunostaining for <i>Salmonella</i> Δ<i>sipA</i> or Δ<i>sopE</i>_<i>2</i> (red) and the GFP-expressing SPI2 reporter (pM973; green) in small intestinal tissue sections at day 4 p.i.. Counterstaining with E-cadherin (white) and DAPI (blue). Bar, 5μm. <b>(K)</b> Quantitative analysis of the percentage of intraepithelial <i>S</i>. Typhimurium expressing the SPI2 reporter. All microcolonies from three tissue sections per infected neonate were analyzed (n = 3) at day 4 p.i.. Results represent the mean ± SD.