Look into defense genes
Why some do not get sick despite a Sars-CoV-2 infection
07/20/2023, 4:21 p.m
Even when the corona pandemic is over, the virus will remain active as a pathogen in the years to come. A research team wants to solve the mystery of infections without symptoms and finds a specific gene variant.
Researchers have found a genetic basis that helps render coronavirus harmless before symptoms appear. The remarkable thing about it: The identified mutation means that the immune system in the human body can successfully fight the corona virus even before symptoms develop, although it has never come into contact with it before. The researchers assume that the mutation primarily means a gain in time for the immune system: “If you have an army that is able to recognize the enemy at an early stage, that’s a great advantage,” says the epidemiologist Jill Hollenbach, who led the study. in a message from the University of California San Francisco (UCSF).
The gene variant is a mutation that is linked to the so-called human leukocyte antigens, or HLA for short. The mutation, which is referred to as HLA-B*15:01, allows messenger substances to be produced after Sars-CoV-2 has penetrated, which in turn enable the T cells to quickly eliminate the pathogen, although the body has never been confronted with it before.
Thanks to cross immunity
the researchers, their results in the specialist magazine “Nature” were published, in cooperation with the La Trobe University in Australia, could also identify an explanation for this: Accordingly, the T cells that carried HLA-B*15:01 were particularly looked at. The mutation apparently causes the T cells to respond to a specific protein (NQK-Q8) from Sars-CoV-2. This is possible through so-called cross-immunity, because the peptide of the coronavirus is very similar to that of seasonal cold coronaviruses (NQK-A8). “It’s like having soldiers who are prepared for battle and already know what to look for and know those are the bad guys,” Hollenbach continued. The gene variant mentioned cannot prevent the infection of the cell, but rather trigger its rapid and effective combat by the immune system.
For the study, the research team used the data of almost 30,000 people who were already at the beginning of the corona pandemic “Covid-19 Citizen Science Study” participated via app and were also registered with the National Bone Marrow Register and also had to undergo regular Covid-19 tests. They identified a total of 1,428 unvaccinated people who tested positive for Sars-CoV-2 at least once between February 2020 and the end of April 2021. During this time you had to wait a few more days for test results. Covid-19 vaccines did not exist yet.
Greatest protection with gene copy
From all the data, a total of 136 people could be identified who did not feel any signs of illness for at least two weeks either before or after a positive Sars-CoV-2 test. 20 percent of these people carried the gene variant described, compared to only nine percent of those suffering from Covid 19. The protective effect was even clearer in people who carried this gene variant on both alleles: “People who have two copies of HLA-B*15:01 remained asymptomatic eight times more often than people with other gene variants,” wrote the research team.
Risk factors for a severe course of Covid-19 such as age, obesity or diabetes do not seem to play a role in who remained symptom-free. Whether the mutation can even compensate for such risk factors would have to be clarified in other studies. The research team is certain that the current findings of the study could help to break new ground in the future development of drugs and vaccines against Sars-CoV-2.