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Leishmania enriettii amastigotes: demonstration of fibrillar surface
Abstract:
An extensive fibrillar surface was identified in situ by transmission electron microscopy on the amastigote stage of the macrophage intracellular parasite, Leishmania enriettii. Attachment to the amastigote surface of 20-160-nm fibrils was clearly evident on organisms that had been isolated from guinea pigs. Surface fibrils were not detected after in vitro transformation of the amastigote to the promastigote. Incubation of amastigotes in heat-inactivated guinea pig serum containing a high titer of antibodies to L. enriettii followed by exposure to ferritin-conjugated antibody to guinea pig IgG resulted in labeling of surface fibrils, a result indicating that these fibrils are of parasite origin. Shedding of labeled fibrils was also evident.
Insights
Researchers discovered extensive surface fibrils on Leishmania enriettii amastigotes. These parasite-derived fibrils were shed and not observed on promastigotes, offering new insights into parasite structure.
Area of Science:
- Parasitology
- Cell Biology
- Microscopy
Background:
- Leishmania enriettii is a macrophage intracellular parasite.
- The amastigote stage is the intracellular form of the parasite.
- Understanding parasite surface structures is crucial for host-pathogen interactions.
Purpose of the Study:
- To investigate the surface ultrastructure of the Leishmania enriettii amastigote stage.
- To determine the origin and presence of surface fibrils during different life cycle stages.
Main Methods:
- Transmission electron microscopy (TEM) was used to visualize parasite surface structures.
- Parasites were isolated from infected guinea pigs and cultured in vitro.
- Immunolabeling with specific antibodies and colloidal gold was employed to trace fibril origin.
Main Results:
- Extensive fibrillar structures (20-160 nm) were identified on the surface of amastigotes.
- These surface fibrils were observed on parasites isolated from guinea pigs but not after in vitro transformation to promastigotes.
- Immunolabeling confirmed that the surface fibrils are of parasite origin and are shed by the amastigotes.
Conclusions:
- Leishmania enriettii amastigotes possess a unique fibrillar surface structure.
- These parasite-derived fibrils are stage-specific, present on amastigotes but absent on promastigotes.
- The shedding of these fibrils may play a role in parasite-host interactions or immune evasion.