IL6 and infection: Ft cultivated under conditions that preclude host-adaptation (e.g., growth in MHB or on MH-based agar medium) versus those that facilitate host-adaptation [e.g., growth in Brain Heart Infusion broth (BHIB) or replication within isolated MΦ or infected tissues] differs substantially; the former growth conditions impose upon the bacterium a pro-inflammatory phenotype (i.e., the ability to elicit TNF, IL-1β, IL-6, IL-12, and IFN-γ) that Ft fails to exhibit in vivo during natural infection [21].