An experimental challenge model of visceral leishmaniasis by Leishmania donovani promastigotes in mice.

Although visceral leishmaniasis is a fatal disease in humans and dogs, the use of mouse models is important for obtaining a better understanding of the pathogenesis, immunity, and host-parasite interactions of this disease. Such models are also useful for the evaluation of vaccines and chemotherapies for treatment of visceral leishmaniasis. Here, we present our method of experimental inoculation of mice with Leishmania donovani promastigotes. Nutrient-enriched undefined media may be beneficial for laboratory maintenance of promastigotes for maintaining their virulence or infectivity in mice. With this method, we could preserve the infectivity of promastigote lines recovered from inoculated animals and use these lines for further in vivo experiments. Furthermore, the use of cryopreserved stabilates is highly recommended for the reproducibility of experiments. To assess a newly developed method for determination of parasite burden in infected animal tissues, initial comparison of parasite burden in the liver obtained in the classic Leishman-Donovan units (LDU) with values obtained from the new method is recommended. As an example, the association between parasite burden determined by LDU and real-time PCR assay targeting the leishmanial gp63 gene in the liver of mice is presented.