Fig. 3.

IFN-γ ELISpot assay following isoniazid treatment during the acute phase of infection. Female Wistar rats were infected with 10³ CFU of M. tuberculosis strain H37Rv. At day 7, rats were orally treated with isoniazid for 4 weeks. Lungs were harvested at days 1, 7, 21, and 35 for CFU counts. (A) Bacterial burden was enumerated for each time point, and mean numbers of CFU and SDs are shown. (B and C) The ELISpot assay was performed at day 21 (B) and at day 35 (C), and PBMCs were stimulated in vitro in duplicate. ESAT-6, CFP-10, and PPD were used at 10 μg/ml. Four animals were used at each time point, and the mean numbers of SFCs/10⁶ PBMCs ± SDs are shown. *, P < 0.05 (Student's t test), comparison between treated and untreated groups. The experiment was repeated independently twice. CT, control (unstimulated) group.