CTSD and infection: However, maturation of mycobacterial phagosomes stops between the early and late endosome stage, as the late endosomal marker, Rab7, is not detected upon infection of macrophages with virulent M. tb. [36, 37] These observations are in good agreement with the levels of expression of the lysosomal aspartic hydrolase, cathepsin D, which is targeted to phagolysosomes, upon infection (Fig 6).