NOS2 and infection: In order to evaluate how the inter-strain diversity observed so far impacts on the course of in vivo infection, we infected C57BL/6 wild-type mice as well as mice deficient in the antimicrobial enzymes phagocyte NADPH oxidase (p47phox−/−) and nitric oxide synthase 2 (Nos2−/−) with each of the described L. infantum strains and the number of parasites in their livers and spleens were quantified after 15 and 60 days of infection.