Challenge infection with virulent L. donovani parasites showed a significant reduction of splenic and hepatic parasite burden in IRF7–/– mice than wild type mice following immunization with LmCen–/–, suggesting that ablation of type I IFN response is a pre-requisite for the induction of LmCen–/– mediated Th1 immunity against L. donovani infection. This evidence concerns the gene IRF7 and infection.