CCL7 and infection: Our data indicates that the induction of β-chemokines is modulated by infection with Mtb. The increased expression of CCL2, CCL4, CCL5, CCL7, CCL13 and CCL19 in cells infected with the Δ-sigH mutant and the reversal of this phenomenon in a strain where the mutation was complemented, indicates that a SigH-dependent Mtb factor interacts with the host innate immune system to bring about this modulation.