Nonetheless, the use of the MAV_2928 mutant established the possibility that

one protein may have key function in modulating the formation of the phagosome, perhaps by altering initial events. Alternatively, the PPE-PE operon may be part of a complex system influencing or impacting the expression of other bacterial genes or involved in the transport of bacterial proteins. Change in single element concentrations in the bacterial environment can have significant effect on gene regulation [45]. Future studies will address some of the differences found and will possibly provide insights into the Panobinostat mouse mechanisms of pathogenesis and survival of mycobacteria inside the host. Conclusion 1. Inactivation of MAV_2928 alters early stages of macrophage transcription in response to MAC infection. 2. Absence of MAV_2928 affects the concentration of materials inside the MAC vacuole, indicating changes in the transport mechanisms. 3. Investigation of the phagosome membrane components revealed unexpected results for the action of only

one protein, suggesting that MAV_2928 may be involved in the transport of other proteins into the host cell. 4. Future studies will attempt to identify proteins that are secreted by the PPE MAV_2928-dependent mechanism. Methods Bacterial strains and growth conditions Mycobacterium ICG-001 avium strain 109 (MAC 109), a virulent strain in mice initially isolated from blood of a patient with AIDS, was cultured

from 20% glycerol stock onto Middlebrook 7H11 agar supplemented with oleic acid, albumin, dextrose and catalase (OADC; Hardy Diagnostics, Santa Maria, CA) at 37°C for 21 days. For the assays, bacteria were suspended in Hank’s buffered salt solution (HBSS) and passed through a 26-gauge needle 10 times to disperse clumps. check details The suspension was then allowed to rest for 5 min and the upper half was used for the assays. The bacterial concentration was adjusted to 1 × 108 bacteria ml-1 using a McFarland standard. Microscopic observations of the suspensions were carried out to verify dispersion of bacteria. Only well dispersed inocula were used in the described experiments. The 2D6 mutant was cultured from 20% glycerol stock on Middlebrook 7H11 agar containing 400 μg/ml kanamycin. The 2D6 mutant suspension was made as described above. The complemented 2D6 strain [11] was also cultured from 20% glycerol stock and grown on Middlebrook 7H11 agar plates containing 200 μg/ml apramycin [11]. Cells and culture conditions Human monocytic cell line U937 (ATCC CRL-1593.2) was cultured in RPMI-1640 (Gibco Laboratories) supplemented with 10% heat-inactivated fetal bovine serum (FBS; Sigma Chemical), 2 mM L-glutamine. The U937 cells were used between passages 15 to 20 and concentrations of 7 × 106 were seeded in 75 cm2 flasks. The cell line was chosen because of convenience, since the strains grow similarly in U937, THP-1 and monocyte-derived macrophages.