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Fine structure of a new human microsporidian, Encephalitozoon hellem, in culture
P J Didier1, E S Didier, J M Orenstein
1Department of Pathology, Tulane Regional Primate Research Center, Tulane University, Covington, Louisiana 70433.
Abstract:
Encephalitozoon hellem is a new human microsporidian isolated from corneal biopsies and conjunctival scrapings of three AIDS patients and cultured in Madin Darby canine kidney (MDCK) cells. Encephalitozoon hellem and Encephalitozoon cuniculi display different protein profiles with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and unique antibody binding patterns with murine antisera against Western blots of each organism. Developmental stages of E. hellem in culture are similar to E. cuniculi. Meronts are 1.3-2.7 microns in diameter, develop within a parasitophorous vacuole adjacent to the vacuolar membrane, divide by binary fission, and contain one or two discrete nuclei. Sporonts measure 2 x 3 microns, separate from the vacuolar membrane, and have a thickened outer membrane. Sporoblasts display a tri-layered wall and possess the earliest recognized polar filaments. Mature spores measure 1 x 1.5 microns and are more electron-dense than other stages. Each spore contains a single nucleus, a polar tubule with four to nine coils, thin electron-dense exospore and thick, electron-lucent endospore. Although E. hellem and E. cuniculi differ biochemically and immunologically, their fine structure and development are indistinguishable.
Insights
Encephalitozoon hellem, a new microsporidian from AIDS patients, differs from Encephalitozoon cuniculi biochemically and immunologically. However, their developmental stages and fine structures are indistinguishable in culture.
Area of Science:
- Microbiology
- Parasitology
- Cell Biology
Background:
- Encephalitozoon hellem is a newly identified microsporidian parasite.
- This organism has been isolated from AIDS patients with ocular infections.
Purpose of the Study:
- To characterize the novel microsporidian Encephalitozoon hellem.
- To compare E. hellem with Encephalitozoon cuniculi.
Main Methods:
- Isolation and culture of E. hellem in Madin Darby canine kidney (MDCK) cells.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for protein profiling.
- Western blot analysis using murine antisera.
- Electron microscopy for ultrastructural analysis.
Main Results:
- E. hellem exhibited distinct protein profiles and antibody binding patterns compared to E. cuniculi.
- Developmental stages of E. hellem in culture, including meronts, sporonts, sporoblasts, and mature spores, were described.
- Ultrastructural analysis revealed indistinguishable fine structures and developmental processes between E. hellem and E. cuniculi.
Conclusions:
- Despite biochemical and immunological differences, E. hellem shares indistinguishable fine structure and developmental stages with E. cuniculi.
- This study provides a detailed characterization of E. hellem, aiding in its identification and understanding of microsporidian infections.
