In addition, it has been shown that the Bp VS-4718 cost alternative sigma factor RpoS, which is involved in genome-wide regulation of bacterial adaptation to environmental stress (i.e. nutrient limitation), plays a role in Bp induced MNGC formation Autophagy inhibitor [59].

Recently, the molecular mechanism of Bp MNGC formation was revealed by Toesca et al.[60]. The T6SS-1 valine-glycine repeat tail spike protein (VgrG1) possesses a novel fusogenic domain at its C-terminus that mediates cell fusion and allows Bp cell to cell spread. Automated high content imaging (HCI) microscopy is a powerful technique to quantitatively characterize cellular phenotypes at the single cell level in response to bacterial and viral infection, exposure to drug agonists and antagonists and for drug mechanism of action determination [61–69]. This work describes the development of a cell-based HCI immunofluorescence assay

to quantitatively characterize selleck inhibitor the MNGC phenotype induced in murine macrophages upon infection with Bp K96243. As a proof of principle for its applicability in a relevant biological setting, this assay was validated using mutants of Bp that were previously described to be defective for MNGC formation in mouse macrophages [58, 70]. Furthermore, we used the MNGC HCI assay to screen a focused small molecule library to identify compounds that interfere with MNGC formation induced by Bp. Together, the results of these experiments indicated that the HCI MNGC assay can be used in a medium-throughput format to identify and characterize Bp mutants that are defective in their ability to induce MNGCs and to identify small molecules that inhibit this phenotype. Results & discussion Optimization of the MNGC assay To develop an automated high-throughput method for quantitating

MNGCs, RAW264.7 macrophages were either not infected (Figure  1A, Top panel-mock) or infected at an MOI Oxymatrine of 30 with wild-type Bp K96243 (Figure  1A, bottom panel-wild-type Bp). After 2 h excess extracellular bacteria were then eliminated by sequential washes in PBS and cells were further incubated in medium containing kanamycin. At 10 h post-infection macrophages were first fixed, and then immunofluorescence (IF) staining was performed to detect bacteria and cellular structures. Finally, samples were imaged by high-throughput confocal fluorescence microscopy. Cell nuclei were stained with the DNA dye Hoechst 33342 and the cell body with the CellMask DeepRed dye. Bacteria associated with or internalized by macrophages were detected by staining cells with an anti-Burkholderia pseudomallei monoclonal antibody. Figure 1 Quantitative analysis of B. pseudomallei K96243 induced murine macrophage MNGC formation. (A) Representative 20X magnification confocal images of RAW264.7 macrophages that were not infected (mock) or infected with wild-type B. pseudomallei K96243 at a MOI of 30 at 10 h post-infection.