FIG. 4.

Ultrastructural characterization of SmOp- and SmTr-induced phagosomes. To label lysosomes, J774 cells were incubated with 15-nm BSA-gold for 3 h and then washed and infected with SmOp or SmTr variants of M. fortuitum. At 24 h postinfection, cells were fixed and processed for EM as indicated in Material and Methods. (A and B) J774 cells infected with SmOp in phagosomes that fuse with BSA-gold labeled lysosomes. (C and D) J774 cells infected with SmTr inside phagosomes that restrict fusion with lysosomes. Arrows (panels A and B), BSA-gold inside phagolysosomes; arrowheads (panels A and D), BSA-gold inside lysosomes; P, phagosomes; P-L, phagolysosomes; L, lysosomes.