The genetic marker responsible for severe covid protects against HIV

SARS-CoV-2 infection differs greatly between people, while some get seriously ill, others have only mild symptoms or are asymptomatic, it all depends on individual risk factors, such as older age, chronic conditions (such as diabetes) or genetic inheritance.

In autumn 2020, Hugo Zeberg, from the Karolinska Institute (Stockholm), and geneticist Svante Pääbo, from the Max Planck Institute (Germany), demonstrated that a genetic variant inherited from Neanderthals was the main genetic risk factor for covid-19. serious.

In an article published in the journal Nature, Zeberg and Pääbo determined that a group of genes on chromosome 3 was linked to being infected with the SARS-CoV-2 virus.

Months later, both researchers studied this variant in samples of ancient human DNA and observed that its frequency had increased significantly since the last ice age and that it is now “unexpectedly common”.

“This major genetic risk factor for COVID-19 is so common that I began to wonder if it might actually be good for something, like providing protection against another infectious disease.” explains Hugo Zeberg, sole author of the new study published in the journal PNAS.

The genetic risk factor is located in a region of chromosome 3 that consists of many genes, some of which code for receptors in the immune system.

One of these receptors, called CCR5, is used by the HIV virus to infect white blood cells, the study notes.

Zeberg found that people carrying the risk factor for COVID-19 had fewer CCR5 receptors, prompting him to test whether they also had a .

Analyzing patient data from three major biobanks (FinnGen, UK Biobank, and the Michigan Genomic Initiative), he found that carriers of the risk variant of COVID-19 were at risk.

“This shows how a genetic variant can be both good and bad news: bad news if a person contracts COVID-19, good news because it offers protection against HIV infection,” Zeberg reasons.

However, since HIV only emerged during the 20th century, protection against this infectious disease cannot explain why the genetic risk variant of COVID-19 became so common among humans 10,000 years ago.

“We now know that this risk variant for COVID-19 provides protection against HIV. But it was probably protection against another disease that increased their frequency after the last ice age.” Zeberg concludes.