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.

Haemoflagellates: commercially available liquid media for rapid cultivation

The successful cultivation of a variety of haemoflagellates in three different liquid media is reported. These media include medium 199, Grace's insect tissue-culture medium and Schneider's drosophila medium, each in combination with 30% (v/v) foetal calf serum. These media were used to cultivate Old and New World species of visceral and cutaneous human Leishmania, as well as Leishmania species isolated from sandflies, rodents, and reptiles. Four strains of Trypanosoma cruzi, an isolate of T. R-angeli and and an isolate of T. lewisi have also been cultivated in these media. One or more of these media have been used to cultivate 121 strains of haemoflagellates, including at least 14 different species (11 Leishmania and 3 Trypanosoma) and many geographic isolates or strains. The Leishmania include L. braziliensis, L. peruviana, L. mexicana, L. tropica, L. donovani, L. chagasi, L. enriettii, L. hertigi, L. hoogstraali, L. adleri, and L. agamae. Using the Schneider's based medium, we have obtained primary isolates of both cutaneous and visceral Leishmania of man and of experimentally infected laboratory rodents and canines. Freeze-dried preparations of the Schneider's based medium that were reconsituted with distilled water after 24 months of storage at ambient temperature have proven to be suitable cultivation media. This feature makes the media valuable field tools. The various species of human Leishmania cultivated in these media have in our experience demonstrated no differences in growth rate, viability after liquid nitrogen preservation, or infectivity for laboratory animals and tissue-culture cells compared with promastigotes derived from blood-agar cultivation.

Axenic cultivation of Phytomonas davidi Lafont (Trypanosomatidae), a symbiote of laticiferous plants (Euphorbiaceae)

Phytomonas davidi (Trypanosomatidae) originally discovered by Lafont in 1909 on the island of Mauritius was rediscovered in Euphorbia cyathophora in Florida. Successful cultures were established in diphasic medium consisting of duck blood agar and modified Phillips' medium as overlay. Optimal growth was obtained when Mansour's medium was used as overlay and poorest growth when Cowperthwaite's medium buffered at pH 5.0 was utilized for this purpose. Marked changes tending toward choanomastigotes rather than the elongate twisted promastigotes were observed in cultures.