Figure 2.

Comparative lung pathology induced by infection with POA-resistant mutants versus wild-type M. tuberculosis H37Rv (ATCC 27294). (A, B) Hematoxylin and eosin (H&E) staining of one lung from groups of four mice infected with H37Rv wild-type, POA^R 1 [panD1], POA^R 7 [ppsC1], and POA^R 18 [clpC1-7] at 4 (A) and 6 (B) weeks postinfection. Blue scale bars for each group represent 5 mm. (C–J) High-power magnification images of representative individual granulomas in the corresponding infection groups at 6 weeks, stained by H&E (C–F) and Ziehl–Neelsen (G–J). (C–F) Typical granulomas contained lymphocyte aggregates with interspersed epithelioid histocytes and foamy macrophages on the outer rim of the granulomatous lesion. Black scale bars on top right for each group represent 100 μm. (G–J) Clusters of acid-fast bacilli were found mostly in areas rich in foamy macrophages (insets).