IFNG and infection: We next examined the contribution of Pat1 to virulence in vivo using mice lacking the receptors for both IFN-I (Ifnar1) or IFN-γ (Ifngr1) (Ifnar1−/−;Ifngr1−/− double knock out mice), which succumb to infection with WT R. parkeri and can be used to investigate the importance of bacterial genes to virulence8,61.