IFNG and infection: In control macrophages, mycobacteria were internalized and proliferated at first 24 h post-infection but were then eliminated by macrophages at later time points, while IFNγ expression reduced mycobacterial burden at 24 h post-infection but markedly increased mycobacterial growth at later time points compared with control cells (Fig. 3B), suggesting that IFNγ can induce the growth of intracellular mycobacteria similar to cultured mycobacteria (Fig. 2D).