Intracellular survival of mutants compared to WT in human monocytes. Human blood monocytes (1.0x106) from healthy volunteers were infected (MOI 10) with mutants and WT. Intracellular bacteria were quantified after 4 hour of infection, and after 1, 2, & 4 days. The monocytes were lysed in 1 ml of sterile water and 100 μl of 1:500 dilution in sterile water of sample were plated on Middlebrook agar plates supplemented with ADC for CFU counting. A: WT and mutant MAV_4334; B: WT and mutant MAV_5106; C: WT and mutant MAV_1778; D: WT and mutant MAV_3128. Statistical analysis was done using a two tailed, paired Student’s t test. When compared to wild-type a P < 0.05 was considered significant (*) and a P < 0.01 very significant (**).