FIG. 3.

Growth of wt and norB (A), narG (B), and nnrA (C) mutants of B. melitensis in J774A.1 macrophages with or without IFN-γ stimulation. Cells treated or not treated with IFN-γ (10 U/ml) were infected under the conditions indicated in Materials and Methods. At the indicated time p.i., the number of intracellular bacteria was measured and expressed in CFU/well. Measurements performed (six replicates) ± standard deviations are presented. At 48 h p.i., the difference between activated and inactivated samples is statistically significant (P < 0.001 in a standard t test) for the norB and nnrA mutants (panels A and C).