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Phagocytosis and proteinase activity are not related to pathogenicity of E. histolytica
I Montfort1, A Olivos, R Pérez-Tamayo
1Department of Experimental Medicine, Facultad de Medicina, Universidad Nacional Autónoma de México, México City.
Abstract:
To examine the relationship between phagocytosis, proteinase activity and pathogenicity of axenically grown trophozoites of E. histolytica strain HM-1:IMSS four different cultures were used: (1) a culture preserved in our laboratory for over 4 years, which lost its pathogenicity 3 years ago; (2) a culture passaged several times through hamster liver, which lost its pathogenicity recently; (3) a highly virulent culture supplied by another laboratory; and (4) amebas recovered from hamster liver abscesses caused by culture 3. Phagocytosis was measured as erythrophagocytosis. Proteinase activity was determined on azocasein. Pathogenicity was defined as the capacity to cause liver abscesses in hamsters. A negative correlation was found between phagocytic activity and pathogenicity, since amebas unable to cause liver abscesses had the highest phagocytic activity, whereas those recovered from liver abscesses had the lowest phagocytic activity. The percent of phagocytic amebas showed wide variations through a 2-month observation period, with no change in amebic pathogenicity. No correlation was found between the level of proteinase activity and pathogenicity. It is concluded that neither phagocytosis nor proteinase activity is an adequate marker of amebic pathogenicity.
Insights
Phagocytosis and proteinase activity do not reliably predict the pathogenicity of Entamoeba histolytica (E. histolytica) infections. Studies show that less pathogenic amebas exhibit higher phagocytic activity, contrary to expectations.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Parasitology
Background:
- Entamoeba histolytica (E. histolytica) is a protozoan parasite responsible for amebiasis.
- Understanding the factors determining E. histolytica pathogenicity is crucial for disease management.
Purpose of the Study:
- To investigate the correlation between phagocytic activity, proteinase activity, and the pathogenicity of E. histolytica trophozoites.
- To determine if phagocytosis or proteinase activity can serve as reliable markers for E. histolytica virulence.
Main Methods:
- Utilized four distinct E. histolytica cultures with varying known pathogenicity levels.
- Measured phagocytosis via erythrophagocytosis and proteinase activity using azocasein.
- Assessed pathogenicity by the capacity to induce liver abscesses in hamsters.
Main Results:
- A negative correlation was observed between phagocytic activity and pathogenicity; non-pathogenic strains showed higher phagocytosis than virulent strains.
- Phagocytic activity varied significantly over time without altering pathogenicity.
- No correlation was found between proteinase activity levels and pathogenicity.
Conclusions:
- Neither phagocytosis nor proteinase activity are adequate indicators of E. histolytica pathogenicity.
- The relationship between E. histolytica virulence factors requires further investigation beyond phagocytosis and proteinase activity.