This presence of IFN-γ producers was necessary to resolve intra-testicular bacterial infection, as all Ifnγ−/− animals died within 3 days in response to a low (2 × 103 CFUs) dose of L. monocytogenes, whereas 60% of Il17−/−, 80% of Tcrδ−/− and 100% of WT mice were still alive at 8 days after infection (Fig. 5f). Here, IL17A is linked to bacterial infectious disease.