IL6 and infection: Consistent with the virulence phenotype, and in comparison to the other three strains, the ΔltgAltgAΔ30 strain in mice resulted in significantly decreased levels of IL-6 and KC, and decreased bacterial load in the blood at 6 hr post-infection (Figure 6a–b), indicating a loss of fitness of the helix-30 deleted mutant strain in the host.