FIG. 5.

IFN-β-neutralizing antibody attenuates the levels of iNOS and IRF-1 protein expression and of phosphorylated Y701-STAT-1 induced by the LPS mutant, resulting in enhancing intracellular survival in LPS mutant-infected macrophages. Mouse macrophages were infected with the LPS mutant B. pseudomallei at an MOI of 2:1 in the presence or absence of anti-IFN-β (10 μg/ml). After 1 h, the cells were washed with PBS before being cultured in medium containing 250 μg/ml of kanamycin. In this experiment, the antibody was kept in the culture medium throughout the entire period. At 8 h after infection, the levels of iNOS, IRF-1, and actin (A) and of phosphorylated Y701-STAT-1 and STAT-1 (B) from the infected cells were determined by immunoblotting. The number of intracellular bacteria was determined by standard antibiotic protection assay (C). Data represent the means and standard deviations from three separate experiments, each carried out in duplicate. *, P < 0.01 by Student's t test.