In vitro light and electron microscope studies on different virulent promastigotes ofLeishmania donovani in hamster peritoneal macrophages

Ebert, Frank; Buse, Eberhard; Mühlpfordt, H

doi:10.1007/bf00927844

Cited by 14 publications

(7 citation statements)

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“…4). Morphologically, the parasites remained as amastigotes for the first 16 hr; after this there was a sharp increase in promastigote population for [16][17][18][19][20][21][22][23][24] 16 hr at 27TC (Fig. 4), their protein labeling pattern was found to change almost immediately (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Tubulin biosynthesis in the developmental cycle of a parasitic protozoan, Leishmania mexicana: changes during differentiation of motile and nonmotile stages.

Fong¹,

Chang²

1981

Proc. Natl. Acad. Sci. U.S.A.

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Cytodifferentiation in the transmission cycle of the parasitic protozoan Leishmania mexicana amazonensiw was studied in vitro The flagellated motile promastigotes transform into the nonmotile amastigotes in 7 days at 35°C intracellularly in the murine macrophage line J774G8. In medium 199 plus fetal bovine serum, the reverse transformation occurs extracellularly at 2aC in 2 days. Slab gel electrophoresis of leishmanias labeled with [35S]methionine during transformation revealed changes in protein banding patterns. The intensity oftwo protein species with apparent molecular weights of =55,000 increased in the amastigote-to-promastigote differentiation and decreased during the reverse transformation. These two protein species comigrated approximately with a-and f-tubulin of Chlamydomonas flagella in two-dimensional gel electrophoresis. The lower band was further identified as 1-tubulin by immunoprecipitation using rabbit antiserum specific to the /-tubulin ofChlamydomonas axonemes. The biosynthetic change of tubulin was found to correlate with the morphological change of microtubules in leishmanial flagella and cytoskeleton during transformation.Some species of digenetic trypanosomatid protozoa are vectorborn agents pathogenic to man or domestic animals. The cyclic transmission of these agents from one host to another is accompanied by cell differentiation, presumably necessary for their adaptation to a new habitat. The life cycle ofleishmanias consists oftwo developmental stages: an extracellular promastigote form in the alimentary canal of the phlebotomine sandfly and an intracellular amastigote form in the reticuloendothelial system of the mammalian hosts (1, 2). Whereas promastigotes are flagellated and thus actively motile, the amastigotes are sessile and confined to the lysosomal compartment ofmacrophages (3). The ability of leishmanias to undergo cytodifferentiation or transformation is crucial for their parasitic life and hence their pathogenicity in leishmaniases.Previous work on leishmanial differentiation has largely been limited to the transformation from amastigotes to promastigotes (because ofthe ease ofexperimental manipulations in vitro) and to comparison between the two developmental stages. It has been shown that promastigotes and amastigotes differ in their surface coat (4), in antigenic properties (5), in AMP-catabolizing enzymes (6), and possibly in heme content (7). Amastigote-topromastigote transformation has been found to require amino acids and glucose (8). It is accompanied by an increase in polyamine levels (9), in mitochondrial volume (10, 11), and in respiratory rate (12). Cyclic AMP (13), ionophores (14), actinomycin D, puromycin (8), cycloheximide, antileishmanial drugs (15), and lymphocyte factors (16, 17) have been reported to inhibit or to perturb this transformation. These findings indicate the necessity of metabolic adaptation by leishmanias in their transition from mammalian to insect hosts.Of particular relevance to human leishmaniases, however, is the transformation ...

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Section: Resultsmentioning

confidence: 99%

“…This transformation has not been studied except for morphological and ultrastructural observations (18)(19)(20)(21). Technical difficulties concerning culture systems for such investigations have been reviewed (22,23).…”

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confidence: 99%

Tubulin biosynthesis in the developmental cycle of a parasitic protozoan, Leishmania mexicana: changes during differentiation of motile and nonmotile stages.

Fong¹,

Chang²

1981

Proc. Natl. Acad. Sci. U.S.A.

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“…Long-term promastigotes are also longer in size than short-term promastigotes although both contain the same amount of protein. Other investigators have found that the morphology of long-term promastigotes is less variable than that of the shortterm (7). In studies of clones of Trypanosoma cruzi (9) and L. tropica (1 3), the original populations were heterogeneous in nature, and in the case of T. cruzi, clones varied in their growth rates.…”

Section: Discussionmentioning

confidence: 99%

“…Several vaccine strains of L. tropica have been shown to lose their infectivity for man after 1-5 years in culture ( I 2, 16) while other strains have maintained their infectivity for man but show a decreased virulence (2). Similarly, strains of L. donovani have lost their infectivity for hamsters after prolonged cultivation (7,11) while others have retained infectivity but show decreased virulence (1, 17). Ebert et al (7) examined the fate of these long-term cultured promastigotes within hamster macrophages in vitro and found that the promastigotes transformed to amastigotes but failed to replicate; however, the fate of these promastigotes in the mammalian host has not yet been investigated.…”

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confidence: 99%

Effects of Long‐Term in Vitro Cultivation on Leishmania donovani Promastigotes

Nolan

Herman

1985

The Journal of Protozoology

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Promastigotes of Leishmania donovani that had been subcultured in modified Tobie's medium for 2 to 3 years showed decreased infectivity and lack of virulence for hamsters and mice compared to newly transformed promastigotes. Amastigotes derived from these long-term promastigote cultures decreased in number rapidly in hamsters, but only slightly in mice, over a 48-day period. In cultured mouse and hamster macrophages infected in vitro, amastigotes derived from long-term cultures rapidly decreased to low numbers, which persisted. The same pattern was seen in macrophages treated with catalase, an inhibitor of the oxygen-dependent killing mechanism of the macrophage. Promastigotes from long-term cultures also differed from virulent first-passage promastigotes in size, growth patterns in Tobie's medium, and in the quantities of some of their antigens.

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“…Previous studies with L. tropica and L. donovani showed that prolonged in vitro cultivation of promastigotes reduced the infectivity and the virulence of these parasites (11,12). The efficacy of such promastigotes (attenuated by prolonged in vitro cultivation) to induce protective immunity in the host against the Leishmania infections has not been examined.…”

Section: Introductionmentioning

confidence: 99%

Vaccinations with live-attenuated <i>Leishmania major</i> promastigotes and challenge infection with <i>L. major</i> in balb/c mice

et al. 2005

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In vitro light and electron microscope studies on different virulent promastigotes ofLeishmania donovani in hamster peritoneal macrophages

Cited by 14 publications

References 11 publications

Tubulin biosynthesis in the developmental cycle of a parasitic protozoan, Leishmania mexicana: changes during differentiation of motile and nonmotile stages.

Tubulin biosynthesis in the developmental cycle of a parasitic protozoan, Leishmania mexicana: changes during differentiation of motile and nonmotile stages.

Effects of Long‐Term in Vitro Cultivation on Leishmania donovani Promastigotes

Vaccinations with live-attenuated <i>Leishmania major</i> promastigotes and challenge infection with <i>L. major</i> in balb/c mice

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