However, in murine models of pulmonary Streptococcus pneumoniae infection or systemic (i.p.)Listeria monocytogenes infection in the treatment of wild-type mice with AhR ligands, enhanced protective immunity was found against these bacterial pathogens, thereby causing higher survival rates, which could not be observed in Ahr−/− mice [17,19]. Here, AHR is linked to pneumococcal infection.