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Hypnozoites of Plasmodium simiovale
F B Cogswell1, W E Collins, W A Krotoski
1Tulane Regional Primate Research Center, Covington, Louisiana.
The American Journal of Tropical Medicine and Hygiene
|August 11, 1991
Summary
Researchers detected latent Plasmodium simiovale hypnozoites in a rhesus monkey
Area of Science:
- Parasitology
- Primate Malaria
- Hepatology
Background:
- Ovale-type malaria, caused by Plasmodium ovale, is known for relapsing infections due to latent liver stages.
- The existence and detection of these latent stages in simian malaria models are crucial for understanding parasite biology.
Purpose of the Study:
- To report the first detection of latent, pre-erythrocytic hypnozoites of Plasmodium simiovale in a primate model.
- To characterize these tissue stages using advanced microscopy and immunofluorescence.
Main Methods:
- Liver biopsies were obtained from a rhesus monkey (Macaca mulatta) eight days post-inoculation with Plasmodium simiovale sporozoites.
- Immunofluorescence assays were used to detect hypnozoites within hepatic parenchymal cells.
- Tissue samples were subsequently restained with Giemsa for morphological examination.
Main Results:
- Hypnozoites of Plasmodium simiovale were successfully detected in the liver biopsies.
- These latent tissue forms measured approximately 6 micrometers in diameter.
- The hypnozoites were localized within the cytoplasm of hepatic parenchymal cells.
Conclusions:
- This study provides the first evidence of latent, pre-erythrocytic stages (hypnozoites) in ovale-type simian malaria.
- The findings confirm the presence of a dormant liver stage in Plasmodium simiovale, similar to Plasmodium ovale.
- This discovery advances our understanding of malaria parasite relapse mechanisms in non-human primates.