Collectively, these results FG-4592 revealed that the uptake of B. anthracis spores by mammalian cells is essentially the same within germinating and non-germinating in vitro environments. Figure 5 Uptake of B. anthracis spores into mammalian cells cultured

under germinating or non-germinating conditions. RAW264.7 cells (A, D), MH-S cells (B, E), or JAWSII cells (C, F) were incubated with B. anthracis spores (MOI 10) in DMEM, RPMI, or DMEM, respectively, in the presence (+, black bars) or absence (-, white bars) of FBS (10%), and then evaluated at 5 or 60 min by flow cytometry and in the presence of trypan blue (0.5%) for the percentage of cells with intracellular spores (A-C), and, for total cell associated spore fluorescence (D-F), as described under Materials and Methods. (A-C) The data are rendered as the percentage of infected cells with the entire population that has internalized spores. (D-F) The data are expressed as the change

in MFI, normalized to cells at 5 min post infection in FBS-free medium. To generate the bar graphs, data were combined from three independent experiments, each conducted in triplicate. Error bars indicate standard deviations. The P values were calculated to evaluate the statistical significance of the differences in percent infected cells (A) or total intracellular spores (B) between cells incubated in the absence or presence of FBS. Germination state of spores influences the number of viable, intracellular B. anthracis Although the uptake of B. anthracis spores Vorinostat into mammalian cells was independent of the presence or absence of FBS in the culture medium,

it was not clear whether the outcome of infection would also be similar under germinating and non-germinating conditions. To evaluate this issue, the recovery of viable, intracellular B. anthracis was compared subsequent to uptake by RAW264.7 cells in the absence or presence of FBS (10%), using the gentamicin protection assay PRKACG [11, 21, 46, 47]. These studies indicated that there were not significant differences in intracellular CFU after 5 min post-infection (Figure 6). However, after 60 or 240 min post infection, significantly greater CFU were recovered from cells in DMEM EVP4593 lacking FBS relative to cells incubated in the presence of FBS (Figure 6). To evaluate whether these differences might be attributed strictly to the presence or absence of FBS, similar studies were conducted in the absence of FBS, however this time using spores that had been pre-germinated for 30 min with DMEM supplemented with L-alanine/L-inosine (both at 10 mM). Similar to spore uptake in the presence of FBS, significantly fewer CFU were recovered from cells incubated with pre-germinated spores in the absence of FBS relative to cells incubated with dormant spores in DMEM lacking FBS (Figure 6).