Trypanosoma lewisi, T. acomys and T. cruzi: a method for their cultivation with mammalian tissue

In vitro cultivation of Trypanosoma acomys: production of insect stages and bloodstream forms

When Trypanosoma acomys bloodstream forms were cultivated at 37 degrees C in Schneider's Drosophila medium supplemented with 20% (v/v) heat-inactivated foetal calf serum (FCS), with Microtus agrestis embryonic fibroblasts in RPMI 1640 medium supplemented with 20% FCS or in Baltz's medium supplemented with 10% FCS, the parasites transformed and largely remained as epimastigotes. Epimastigotes were also usually the commonest stage observed when the parasites were co-cultivated with a mosquito cell line at 27 degrees C. However, if these cultures were initiated with the supernatant suspensions from fibroblast cultures that had been cryopreserved, trypomastigotes, including bloodstream-like forms, were the predominant stage for the first 4 days of culture. It is suggested that the glycerol supplement or the temperature changes stimulated this unusual morphogenesis. At 27 degrees C, T. acomys was incapable of multiplying and died when cultured in fresh Schneider's Drosophila medium supplemented with 20% FCS, but co-cultivation with the mosquito cell lines or cultivation in cell-free supernatants from 1-week-old mosquito cell cultures was successful at this temperature; most of the parasites multiplied as epimastigotes.

Trypanosoma acomys (Wenyon, 1909): continuous culturing with a mouse fibroblast cell-line (A9)

The continuous culturing of Trypanosoma acomys in the presence of a murine areolar-adipose cell line (A9) was possible for the 1st time. The trypanosomes were cultured at 37 degrees C with A9 in DMEM supplemented with 20% heat inactivated fetal bovine serum, using an initial inoculum from primary cultures of lung or blood clots from infected spiny mice. The cultures were maintained for 115 days and underwent 15 passages before termination and cryopreservation. Using this culture system T. acomys subcultures were initiated from 3 different initial inocula (3 x 10(4), 1.5 x 10(5) and 7.4 x 10(5) parasites/ml) and growth curves revealed that the lowest inoculum gave the best growth pattern. This inoculum yielded a population doubling time of less than 12 h for 4 days, a high peak density of 7 x 10(6) parasites/ml and the most gradual decline compared to the other 2 inocula. Rosetting epimastigotes and nests of amastigotes were observed in close association with the feeder layer cells. Epimastigotes were the most predominant form in culture supernatants but other morphological forms observed included trypomastigotes and sphaeromastigotes.

Trypanosoma acomys (Wenyon, 1909): reproductive forms and course of parasitemia in the natural host Acomys cahirinus (Desmarest, 1819)

Trypanosoma acomys (Stercoraria, Trypanosomatidae) was studied in the laboratory-bred spiny mouse Acomys cahirinus. Only trypomastigotes were found in peripheral blood, whereas the thymus of experimentally infected A. cahirinus showed amastigote syncytial reproductive forms whose nuclei of nuclei ranged from 2 to 128. These reproductive forms were detected 9-10 days after the i.p. injection of spiny mice with trypanosomes obtained from primary lung cultures. Transitional trypomastigote-like forms were observed in the thymus; no reproductive or diving forms were encountered in any other tissue, including blood. The course of the parasitemia in spiny mice inoculated i.p. with 1.2 x 10(6) parasites from 26- to 32-day-old cultures initiated from infected lungs was studied. A similar, characteristic pattern was observed in both male and female hosts. Four phases were recognized: latent, logarithmic, stationary, and decline. These phases ended on days 2, 14, 98, and 154 postinoculation, respectively. The decline phase was gradual and the parasites could not be detected by day 154 postinoculation. In contrast, inoculation from older cultures (35-50 days old) showed longer latent and logarithmic phases, a shorter stationary phase, and a sharp drop in parasite density during the decline phase; the parasites were not detected in the peripheral blood by 120 days postinoculation.