How Malaria Parasites Hide from the Human Immune System
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How malaria parasites hide from the human immune system:
[...] Plasmodium falciparum, the parasite responsible for malaria, infects red blood cells as part of a complex life cycle. Once inside a cell, the parasite produces proteins that dock on the cell's exterior and make it stick to blood vessels so that it won't be carried to the spleen, where it would otherwise get removed from the body.
Typically, only the early life stages of the parasite circulate in the blood, while older parasites thrive inside red blood cells adhered to blood vessels, says Silvia Portugal, a biologist who led the work while at Heidelberg University Hospital in Germany.
[...] But when the researchers compared which genes were turned on or off in samples taken from asymptomatic people in the dry season and symptomatic people in the wet season, they saw that 1,607 genes had distinct seasonal patterns. In the dry season, 1,131 genes were turned on that were off in wet-season parasites. Another 476 were turned off in dry-season parasites, suggesting that when the wet season ends, P. falciparum may alter its genetics to make red blood cells less sticky. That allows the parasite to replicate and persist without setting off alarm bells that alert the immune system to fight the infection.
Blood cells infected with malaria use certain proteins to adhere to blood vessels almost like Velcro, Portugal says. The loss of stickiness could be because the parasite makes fewer of these proteins, or because the proteins are different in some way.
Journal Reference:
Carolina M. Andrade, Hannah Fleckenstein, Richard Thomson-Luque, et al. Increased circulation time of Plasmodium falciparum underlies persistent asymptomatic infection in the dry season, Nature Medicine (DOI: 10.1038/s41591-020-1084-0)
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