Figure 8.

The lack and truncation of PE_PGRS33 is responsible for an increased virulence phenotype of Mtb in lung tissue during the chronic/persistent Mtb infection in mice. Quantitative and qualitative histopathological analysis were performed on lung sections of mice infected with Mtb H37Rv, the MtbΔ33 mutant and complemented strains (MtbΔ33::33^all11, MtbΔ33::33^all3, and MtbΔ33::33^all6). At least six lung sections per mouse for all 5 groups were analyzed in different points. Extent of tissue damage was assessed as: (A) number of granulomas; (B) average surface of granulomas; and (C) percentage of tissue surface area with lesions with respect to total lung area. (D) Granuloma extension and distribution in lung tissue were evaluated after performing histopathological analysis of lung sections stained with H&E at days 49 post-infection (200x magnification). Representative slides are shown. ^*p < 0.05 and ^**p < 0.01 (Student's t-test).