Skip to main content
Figure 4 | BMC Infectious Diseases

Figure 4

From: Contribution of different pneumococcal virulence factors to experimental meningitis in mice

Figure 4

Phagocytosis and intracellular survival of S. pneumoniae strains in microglial cells. A. BV2 cells were infected for 3 h with bacteria (moi = 10). A minimum of 200 BV2 cells were examined, and any cell containing one or more bacteria was considered as phagocytic. B. Quantification of acidic phagosomes in microglial cells infected with S. pneumoniae. Hoechst-labelled bacteria were exposed to BV2 cells (moi = 10) for 3 h, and the acidotropic dye LysoTracker Red DND-99 was added. Accumulation of the dye in phagosomes containing Hoechst-labelled bacteria was observed by epifluorescence microscopy. At least 200 BV2 cells were counted, and the number of cells with bacteria-containing acidic phagosomes was scored. The percentage of colocalisation was determined as the number of BV2 cells with pneumococci-containing phagolysosomes over the total number of phagocytes. C. Intracellular survival of pneumococcal strains within microglial cells. BV2 cells were infected for 3 h with S. pneumoniae strains (moi =10), washed to eliminate extracellular bacteria, and treated with antibiotics (time 0). After 4 h, BV2 were lysed, and viable counts were performed. The SI was calculated as the number of cfu detected at time 4 h divided by the cfu number at time 0 h post-phagocytosis. For all above assays, data from 4–5 independent experiments are shown as mean ± SD. Asterisks indicate statistical significance (*, p < 0.05; Bootstrap method).

Back to article page