IFNG and infection: Mycobacteria isolated from control macrophages displayed a higher expression level of PpsB but not AmiD at 48 and 72 h post-infection compared with cultured bacteria, whereas mycobacteria isolated from IFNγ-expressing cells showed increased expressions of both proteins at all time points compared with cultured bacteria (Fig. 4B), suggesting intracellular IFNγ is capable of triggering PpsB and AmiD expression in M. tuberculosis within macrophages.