The eerie video you’re about to watch captures the moment when a malaria parasite invades a human red blood cell – this is the first time that such an event has been caught in moving pictures.
The Plasmodium parasite responsible for malaria is transmitted by the bite of infected mosquitoes, and is thought to kill almost 1 million people worldwide each year.
Jake Baum at the Walter and Eliza Hall Institute of Medical Research in Melbourne, Australia, and colleagues used transmission electron microscopy and 3D immuno-fluorescence microscopy to record a series of still images during the 30-second-long invasion and combined them into a movie.
To boost their chances of catching a Plasmodium parasite in the act of attacking a red blood cell the team controlled the process using two drugs. The first – heparin – prevents parasites entering a new red blood cell, while the second – E64 – prevents their exit. Carefully timing the treatments meant “we knew we were going to get huge number of invasion events,” says Baum.
The parasites produce a protein called the tight junction marker and use it to attach to and drill into red blood cells, says Baum. “At the beginning of invasion it’s a dot, as the parasite enters the cell it becomes a beautiful circle, and then the marker is behind the parasite.”
The movie shows that invasion is not a well-ordered process, as we had thought, says Baum. “Initial attachment using the tight junction marker is the main switch, and then the parasite does everything at once.” Simultaneously, it releases a vacuole to live in and switches on a motor complex allowing it to move within the cell.
Kiaran Kirk at the Australian National University in Canberra says the “clever cell preparation and stunning microscopy” is a “tour de force”.
The movie could have implications for the treatment of malaria too. Leann Tilley of La Trobe University in Melbourne, Australia, says the results confirm that interfering with the master switch would stop the parasites from entering red blood cells and “thereby stop disease”.
Journal reference: Cell Host & Microbe, DOI: 10.1016/j.chom.2010.12.003
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