Figure 4. Contribution of Fischer 344 rat BMDM nitric oxide production on intracellular replication of Francisella strains.
(A) Supernatants from intracellular replication assays (3, 24, 48 and 72 h) were analyzed for the presence of nitric oxide. Concentrations of nitric oxide following infection of BMDM with (i) subsp. novicida, (ii) LVS, (iii) subsp. holarctica, and (iv) subsp. tularensis. Results are representative of three separate experiments. (B) Fischer 344 BMDM were seeded in 96 well plates (2×105 cells/well) and allowed to adhere. Cells were infected with 10 MOI of (i) subsp. novicida or (ii) subsp. tularensis for 2 hr, with or without N-methyl-L-arginine acetate salt as a nitric oxide inhibitor, treated for 1 hr with gentamicin, and incubated at 37°C for 72 hr. At the indicated time points (3, 24, 48 and 72 h) after challenge, cells were lysed and serial dilutions were plated to quantify intracellular bacteria. Results are representative of two separate experiments. * P<0.001, ** P<0.05.