There are evidences that IL-17 plays a protective role against the primary infection of some intracellular bacteria, such as Francisella tularensis and Listeria monocytogenes[55]–[57], while it has been shown to have a limited role with other intracellular primary infections, such as tuberculosis [58] or a controversial role like in Salmonella enterica[59]–[61]. The gene discussed is IL17A; the disease is infection.