Intracellular growth of CDC1551 and HN878 and global transcriptome of BMM during infection. (A) Growth of CDC1551 and HN878 in macrophages up to 48 hpi. The cells were infected with a multiplicity of infection (MOI) of 5 (bacteria per phagocyte) for 3 hours. Equal numbers of BMM were seeded at the start of infection with CDC1551 and HN878. At 3 (T = 0), 24 and 48 hpi, cells were lysed and serial dilutions of the homogenates were plated to determine the CFU. The viability of the infected cells, measured by trypan blue exclusion, did not change significantly till the end of the experiment (48 hours). (B) Venn diagram of microarray data showing macrophage genes significantly differentially expressed (at least 2 fold change in expression and P ≤ 0.05) by CDC1551 and HN878 at 6 and 24 hpi. (C and D) Transcriptional profile of individual host genes differentially expressed by CDC1551 (C) and HN878 (D) infection at 6 hpi. (E and F) Total number of differentially expressed macrophage genes by CDC1551 (E) and HN878 (F) infection at 24 hpi. The data presented in (C-F) is derived from microarray analysis of differentially expressed macrophage genes during infection by Mtb . Each spot represents a gene and all genes are ranked based on their relative expression ratio (Mtb-infected vs. uninfected cells). The microarray results were obtained from three independent RNA samples per experimental group (infected or uninfected).