Isolation of blood and intracellular forms ofTrypanosoma cruzifrom rats and other rodents and preliminary studies of their metabolism

Abstract

SummaryIsolation of blood and intracellular forms of Trypanosoma cruzi was made mainly from rats (90–110 g) which had received 580 rad of whole-body γ-irradiation not more than 24 h before subcutaneous inoculation with 107 trypomastigotes of the Sonya strain of T. cruzi. Unirradiated chinchillas (250–350 g) were, however, used for some experiments. Blood forms were isolated using a technique involving differential centrifugation to remove most of the erythrocytes and DEAE–cellulose chromatography to remove the remaining blood cells. Overall recoveries were usually in the range 30–70%. Parasites were mainly (approximately 98%) broad forms and were motile, metabolically active (as judged by respiratory and radio-tracer incorporation studies) and had lost none of their infectivity for mice. Intracellular forms were isolated from hind-limb muscle tissue. This was disrupted in an MSE tissue homogenizer and the homogenate incubated with DNase, collagenase and trypsin. Parasites, contaminated only by a few blood cells, were then obtained by differential centrifugation. For purer preparations, a terminal sucrose gradient step was used. Recoveries ranged between 40 and 70%. About 1–3% of the parasites isolated were epimastigotes and trypomastigotes; the remainder are probably best collectively termed ‘amastigotes’, though they were pointed and most had a short, free flagellum. They were undamaged as judged by light and electron microscopy and metabolically active as judged by respiratory and radio-tracer incorporation studies. However, the infectivity for mice of both these purified preparations and the initial cell homogenates could be accounted for by the epimastigotes and trypomastigotes present in them. Preliminary biochemical studies with isolated parasites have shown that blood, intracellular and culture forms of T. cruzi have a respiratory system which is in part sensitive to CN- and that all forms synthesize nucleic acids and proteins when incubated in vitro. There appears, however, to be a lack of DNA synthesis in blood stages, and thus it is not surprising that these forms do not divide.

Infectivity of amastigotes of Trypanosoma cruzi

“…Using amastigote-like forms from different sources, contradictory results have been reported (ABRAHAMSON et al- 1 ; ARAtfJO et al 3 ; CARVALHO et al 6 ; GUTTERIDGE et el. 10 ; HUDSON et alU; LANAR13; MAcCABE et al«; PANRIBEIRO et al"; SEGURA et al 25 ;…”

Major surface proteins and antigens on the different in vivo and in vitro forms of Trypanosoma cruzi

“…Mice, C57BL/6, were inoculated with 104 bloodstream trypomastigotes and bled about 12 days later by heart puncture using trisodium citrate saline as an anticoagulant [11]. The bloodstream trypomastigotes were separated from red blood cells by a Percoll step gradient [12], rinsed twice in trisodium citrate saline and separated from host cells and platelets by passage over a 5 ml DEAE-ceilulose column equilibrated with PSG (I = 0.206.…”

Effect of allopurinol on Trypanosoma cruzi: metabolism and biological activity in intracellular and bloodstream forms

“…HPP metabolism by bloodstream forms. Bloodstream trypanosomes (Peru strain) were grown in and isolated from chinchillas by the procedures described by Gutteridge et al (6). The trypanosomes, contaminated with approximately 1O0o erythrocytes, were suspended in a purine-free medium (4) containing 32 FM (4.3 p,g/ml) [14C]HPP (specific activity, 52.4 ,uCi/,umol) and incubated for 6 hours at 31°C (Table 1).…”