The expression of CCL4 appeared to be significantly higher in cells infected with the Mtb:Δ-sigH mutant relative to either Mtb or the complement, at the 0 hr post-infection time-point, while the expression of CCL2, CCL5 and CCL7 appeared to be significantly higher in cells infected with the mutant relative to Mtb or the complemented strain, at 4 hrs post-infection. This evidence concerns the gene CCL2 and infection.