Through this mechanism, parasites causing malaria become “invisible”

It is estimated that from 300 to 500 million people are infected annually, and almost 600,000 die of this disease. Causing her a sickle godded (Plasmodium Falciparum) goes to the body by a bite of the Widliszka mosquito (Anopheles). According to research published in the magazine “Nature Medicine”, this parasite can in an unusual way can hide from the body's immune system – sometimes for years.

After getting into the human organism, the rabid gets into the red blood cells for replication – but must avoid alerting the immune system or the removal by the spleen, which filtering defective blood cells. His way to avoid threats is based on a set of about 60 genes called VAR. When the parasite turns on one of them, it begins to produce a special protein – thanks to it, the infected red blood cell “sticks” into the wall of the blood vessel, which makes it not reaching the spleen.

The human body is not completely defenseless. Within a week, the immune system can produce antibodies that recognize protein. Then the parasite turns off one gene and triggers another, thus avoiding detection and thus extends the infection.

Scientists were interested in what happens after the malaria spoder “passes” through the whole set. Re -activation of one of the previously used genes should end in an elimination, and yet parasites can remain in the body for years – chronic malaria infection can persist for a decade or longer.

To solve the puzzle, researchers used the technologies of sequencing individual cells to assess how individual parasites manage gene expression. They discovered that while many of them activate only one VAR gene at once, some had two or three enabled, while others did not activate any.

Researchers explained that the germs expressing several genes were probably caught on switching between one and the other. It was surprising, however, to find completely invisible parasites.

– This shows a completely new aspect of how malaria sneaks out the diagnosis by our immune system – said Francesca Florini from Weill Cornell Medicine, co -author of the study.

Without expression of the VAR gene, infected blood cells lose their ability to attach to the walls of blood vessels, so how do they manage to avoid transport to the spleen? Researchers suspect that they are hiding in the bone marrow.

The results indicate that in regions where malaria is endemic, adults can be asymptomatic carriers of parasites. If the widliszek mosquito bite them, he can transfer the germs to the next person they bite.

– Actions aimed at controlling malaria focus on the treatment of people, usually children who show symptoms – said Kirk Deitsch from Weill Cornell Medicine, co -author of the article. – These discoveries suggest that we must take into account asymptomatic adults who can transfer potentially infectious parasites. This means that the elimination of malaria from any geographical region will be more complicated than expected – he added.

The research team plans to conduct field research in West Africa to locate these hidden cases. Finding them and finding out how malaria parasites use this discovered mechanism to protect, can help in the fight against chronic cases of malaria.