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Phagocytosis and proteinase activity are not related to pathogenicity of Entamoeba histolytica
I Montfort1, A Olivos, R Pérez Tamayo
1Departamento de Medicina Experimental, Facultad de Medicina, UNAM, México.
Abstract:
To examine the relationship between phagocytosis, proteinase activity and pathogenicity of axenically grown trophozoites of E. histolytica of strain HM-1:IMSS four different cultures were used: 1) a culture preserved in our laboratory for over 4 years, that lost its pathogenicity 3 years ago; 2) a culture passaged several times through hamster liver, that lost its pathogenicity recently; 3) a highly virulent culture supplied by another laboratory; and 4) amebas recovered from hamster liver abscesses caused by the latter culture. 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 increased progressively in all cultures through a 2-month observation period. No correlation was found between the level of proteinase activity and pathogenicity. It is concluded that neither phagocytosis nor proteinase activity are adequate markers of amebic pathogenicity.
Insights
Phagocytic activity in E. histolytica trophozoites showed a negative correlation with pathogenicity, with non-pathogenic strains exhibiting higher phagocytosis. Proteinase activity did not correlate with pathogenicity, indicating neither is a reliable marker for virulence.
Area of Science:
- Medical Parasitology
- Microbiology
- Infectious Diseases
Background:
- Entamoeba histolytica (E. histolytica) is an enteric protozoan parasite.
- Virulence factors of E. histolytica are not fully understood.
- Pathogenicity is linked to the parasite's ability to invade host tissues.
Purpose of the Study:
- To investigate the relationship between phagocytic activity, proteinase activity, and pathogenicity in E. histolytica.
- To determine if phagocytosis or proteinase activity can serve as markers for E. histolytica virulence.
Main Methods:
- Four E. histolytica cultures with varying pathogenicity were used: long-term preserved, recently attenuated, highly virulent, and recovered from abscesses.
- Phagocytosis was quantified via erythrophagocytosis.
- Proteinase activity was measured using azocasein.
- Pathogenicity was assessed by the ability to induce liver abscesses in hamsters.
Main Results:
- A negative correlation was observed between phagocytic activity and pathogenicity.
- Non-pathogenic amebas demonstrated the highest phagocytic activity, while those from abscesses showed the lowest.
- Phagocytic ameba percentage increased over a 2-month period in all cultures.
- No correlation was found between proteinase activity and pathogenicity.
Conclusions:
- Phagocytosis is inversely related to E. histolytica pathogenicity.
- Proteinase activity does not correlate with the virulence of E. histolytica.
- Neither phagocytosis nor proteinase activity are reliable indicators of E. histolytica pathogenicity.