Entamoeba dispar: ultrastructure, surface properties and cytopathic effect

Area of Science:

• Microbiology
• Cell Biology
• Parasitology

Background:

• Entamoeba dispar is a distinct species from Entamoeba histolytica, differentiated by biochemical and molecular criteria.
• Understanding the cytological differences is crucial for accurate diagnosis and treatment.

Purpose of the Study:

• To compare the cytological features of Entamoeba dispar and Entamoeba histolytica.
• To elucidate the differences in their cytopathic effects on epithelial cells.

Main Methods:

• Axenic culture of E. dispar and E. histolytica trophozoites.
• Light and transmission electron microscopy for morphological analysis.
• Toluidine blue staining for glycogen deposits.
• Concanavalin A agglutination and cellular microelectrophoresis for surface properties.
• Ussing chamber experiments to assess cytopathic effect on MDCK cell monolayers.

Main Results:

• E. dispar trophozoites are more elongated with a single frontal pseudopodium and a noticeable uroid.
• E. dispar exhibits cytoplasmic metachromasia due to glycogen deposits, unlike E. histolytica.
• E. dispar has finer nuclear peripheral granules, a thinner surface coat, lower concanavalin A sensitivity, and higher negative surface charge.
• E. dispar demonstrates a slower cytopathic effect on epithelial cells, with minimal phagocytosis compared to E. histolytica.

Conclusions:

• Morphological and ultrastructural differences exist between E. dispar and E. histolytica.
• E. dispar possesses a moderate but slower and less intense in vitro lytic capacity on epithelial cells compared to E. histolytica.