Importantly, we further observed that the increased susceptibility of IL-17A−/− mice after infection with an elevated dose of Mtb was abolished by an additional deficiency of IL-17F, as the wildtype and IL-17A/F−/− mice displayed similar survival times, whereas IL-17A−/− mice had to be euthanized significantly earlier (Figure 7D). The gene discussed is IL17F; the disease is infection.