3.5.4.2	malfunction	deletion of the AAH locus in intact parasites establishes that AAH is not an essential gene and that -/-aah cells are capable of salvaging the same range of purine nucleobases and nucleosides as wild type Leishmania donovani. The aah null mutant is able to infect murine macrophages in vitro and in mice, although the parasite loads in both model systems are modestly reduced compared with wild type infections	720058