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Zymodeme alteration of Entamoeba histolytica isolates under varying conditions
R M Mukherjee1, K C Bhol, S Mehra
1Kothari Centre of Gastroenterology, Kothari Medical Centre, Calcutta, India.
Abstract:
Cysts of Entamoeba histolytica obtained from 2 asymptomatic subjects were cloned in vitro and the isoenzyme patterns and virulence of the cultures derived from them were determined. Incubation in Diamond's TYI-S-33 medium with Crithidia sp. for 80 d resulted in a change from zymodeme III to zymodeme II, with consistent virulence. Axenization by replacing Crithidia sp. with crithidial lysate had no further effect on the zymodeme but the virulence of the amoebae was attenuated. A reversal to zymodeme III, together with augmentation of virulence, was observed on the 20th day after transfer of axenic amoebae to Diamond's TYSGM-9 medium containing the original bacterial flora. The possibility that the isoenzyme pattern determining the zymodeme and the virulence behave as 2 independent variables in E. histolytica is discussed.
Insights
Entamoeba histolytica isoenzyme patterns and virulence can change in vitro. Culture conditions, including bacterial presence, influence these characteristics, suggesting independent variability.
Area of Science:
- Medical Parasitology
- Molecular Biology
- Microbiology
Background:
- Entamoeba histolytica is an intestinal parasite causing amoebiasis.
- Understanding factors influencing E. histolytica virulence and genetic markers is crucial for disease control.
Purpose of the Study:
- To investigate the in vitro changes in isoenzyme patterns (zymodemes) and virulence of Entamoeba histolytica cultures.
- To determine the impact of culture conditions, including axenization and bacterial presence, on E. histolytica characteristics.
Main Methods:
- Cloning of Entamoeba histolytica cysts from asymptomatic subjects.
- In vitro cultivation in different media (TYI-S-33, TYSGM-9) with and without Crithidia sp. or lysate.
- Isoenzyme pattern analysis (zymodeme determination) and virulence assessment.
Main Results:
- Cultivation in TYI-S-33 medium with Crithidia sp. shifted zymodeme from III to II, maintaining virulence.
- Axenization (removing Crithidia sp.) did not alter zymodeme but attenuated virulence.
- Reintroduction of original bacterial flora reversed zymodeme to III and increased virulence.
Conclusions:
- Entamoeba histolytica zymodeme and virulence are potentially independent variables.
- Culture environment significantly influences E. histolytica isoenzyme profiles and pathogenicity.
- These findings have implications for studying parasite evolution and virulence factors.