At the 24 hr post-infection time-point, the average expression of CCL2, CCL5, CCL13 and CCL19 was induced to higher levels in cells infected with the Mtb:Δ-sigH mutant (59.7, 37.7, 12.3 and 13.9-fold respectively), relative to cells infected with Mtb (39.8, 26.9, 1.5 and 2.76-fold respectively) or Mtb:Δ-sigH:CO (7.4, 2.2, 1.7 and 3.9-fold respectively) (Figure 2C). Here, CCL13 is linked to infection.