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Invasion and early development of Sarcocystis muris (Apicomplexa, Sarcocystidae) in tissue cultures
Abstract:
Ultrastructural observations on the invasion and early development of merozoites (bradyzoites) of Sarcocystis muris in Madin-Darby canine kidney (MDCK) cells are presented. Invading merozoites cause the host cell plasmalemma to invaginate; they form a membrane junction (moving junction) and move into the host cell where they are enclosed in a primary parasitophorous vacuole (PV). Within 30-45 min after becoming intracellular, merozoites begin to vacate the newly established primary PV and move, forming a new membrane junction, into a secondary PV. Simultaneously with the movement of the parasite, the contents of dense granules in the apical part of the merozoites are shed by exocytosis into the lumen of the developing secondary PV. A lamella of the endoplasmic reticulum of the host cell becomes attached to the PV membrane, forming a PV limited by three host cell membranes.
Insights
This study details how Sarcocystis muris merozoites invade Madin-Darby canine kidney cells, forming a unique three-membrane parasitophorous vacuole. These parasites undergo significant intracellular development and migration within host cells.
Area of Science:
- Parasitology
- Cell Biology
- Microbiology
Background:
- Sarcocystis muris is an intracellular parasite with complex life cycle stages.
- Understanding parasite invasion mechanisms is crucial for developing targeted interventions.
- Madin-Darby canine kidney (MDCK) cells provide a model system for studying host-pathogen interactions.
Purpose of the Study:
- To investigate the ultrastructural details of Sarcocystis muris merozoite invasion and early development in MDCK cells.
- To elucidate the formation of the parasitophorous vacuole (PV) and host-parasite membrane interactions.
Main Methods:
- Ultrastructural observation using electron microscopy.
- In vitro culture of Sarcocystis muris in MDCK cells.
- Detailed morphological analysis of parasite-host cell interactions.
Main Results:
- Merozoites induce host cell plasmalemma invagination and form a moving junction during invasion.
- Parasites are initially enclosed in a primary PV, then migrate to a secondary PV within 30-45 minutes.
- Dense granule contents are released into the PV, and the PV becomes enclosed by three host cell membranes, including endoplasmic reticulum.
Conclusions:
- Sarcocystis muris exhibits a dynamic invasion process involving membrane remodeling and parasite migration.
- The formation of a triple-membrane-bound PV is a key feature of early Sarcocystis development in MDCK cells.
- These findings contribute to understanding the cellular strategies employed by Sarcocystis parasites during host cell entry.