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Fine structure of Encephalitozoon cuniculi from rabbits, mice and hamsters
Abstract:
Fine structure and development of Encephalitozoon cuniculi from rabbits were studied in rabbit choroid plexus (CP) cell cultures and were compared to hamster and mouse microsporida. Sporoplasms had a single limiting membrane and contained a large nucleus. Proliferative forms (schizonts) had double outer membranes, the outermost being associated with the formation of the limiting membrane of vacuoles formed within the host cell cytoplasm. These organisms were often binucleate and divided to form sporonts. Sporonts divided once to form 2 sporoblasts which developed into electron-dense spores. Spores had a thick, 3-layered wall and contained a polar filament. The developmental cycle of E. cuniculi in rabbit CP cultures progressed rapidly. Sporoplasms were observed in host cells at 3 hr postinoculation (PI). By 24 hr PI proliferative forms were associated with host cell cytoplasmic vacuoles which contained developing organisms. Mature spores were present in vacuoles by 2 days PI, indicating that the life cycle in the CP system is approximately 48 hr. The fine structure and the sequential developmental cycle of the mouse and hamster isolates were observed to be identical to those of the rabbit isolate and different from those of the genus Nosema. It is proposed, therefore, that the 3 organisms represent the same species, Encephalitozoon cuniculi.
Insights
Encephalitozoon cuniculi, a microsporidian parasite, rapidly develops in rabbit choroid plexus cell cultures within 48 hours. Its fine structure and development are consistent across rabbit, mouse, and hamster isolates, suggesting they are the same species.
Area of Science:
- Parasitology
- Cell Biology
- Microbiology
Background:
- Microsporidia are obligate intracellular parasites with a complex life cycle.
- Encephalitozoon cuniculi is a significant pathogen in rabbits and can infect other mammals.
- Understanding the developmental cycle and fine structure is crucial for diagnosis and treatment.
Purpose of the Study:
- To investigate the fine structure and developmental cycle of Encephalitozoon cuniculi in rabbit choroid plexus (CP) cell cultures.
- To compare the development of rabbit Encephalitozoon cuniculi with microsporidia from hamsters and mice.
- To determine if different isolates represent the same species.
Main Methods:
- Cultivation of Encephalitozoon cuniculi in rabbit choroid plexus (CP) cell cultures.
- Electron microscopy to study the fine structure of developmental stages.
- Comparative analysis of developmental cycles across different host isolates.
Main Results:
- Sporoplasms, schizonts, sporonts, sporoblasts, and mature spores of Encephalitozoon cuniculi were characterized.
- The developmental cycle in rabbit CP cultures was rapid, with mature spores observed by 2 days postinoculation (PI).
- The fine structure and developmental cycle were identical in rabbit, mouse, and hamster isolates, differing from the genus Nosema.
Conclusions:
- The developmental cycle of Encephalitozoon cuniculi in rabbit CP cells is approximately 48 hours.
- The three studied isolates (rabbit, mouse, hamster) are proposed to be the same species, Encephalitozoon cuniculi.
- The findings differentiate Encephalitozoon cuniculi from the genus Nosema based on its developmental characteristics.