CCL2 and infection: Similarly, the expression of CCL2, CCL5 and CCL7 was induced to higher levels in cells infected with the Mtb:Δ-sigH mutant (13.17, 2.2 and 9.2-fold respectively), relative to cells infected with Mtb (4.1, 0.68 and 3.8-fold respectively) or Mtb:Δ-sigH:CO (1.9, 1.8 and 3.8 respectively), at the 4 hr post-infection time-point (Figure 2B).