Has an integral role during the infection of macrophages in the mammalian host. Preference for hydrophobic residues at P1 and P1' and basic residues at P2' and P3'. A model nonapeptide is cleaved at -Ala-Tyr-|-Leu-Lys-Lys-. Binds 1 zinc ion per subunit. Belongs to the peptidase M8 family.