2023-07-19 15:04:58
Researchers have discovered a gene that explains why some people don’t get sick when they breathe in the coronavirus. Your immune cells can fight the pathogen even if you’ve never seen it before.
The corona pandemic is officially over, but there are still some unsolved mysteries about the disease and pathogens. One of them concerns the great difference in the courses of infection. While some people become very seriously ill, others do not notice the pathogen. They don’t catch it even if they’re in close proximity to infected people at home or at work, and are therefore likely to inhale large amounts of the virus.
A team led by Jill Hollenbach from the University of California in San Francisco has now found an explanation: Anyone who is only infected with corona asymptomatically probably has a special variant of the genes that code for the so-called human leukocyte antigen (HLA).
T cells recognize Sars-CoV-2 thanks to cross-immunity to the common cold corona
People who carry the HLA-B15 mutation can produce messenger substances that help killer T cells to recognize Sars-CoV-2 even if the immune system has never been confronted with the virus before. The T cells are then able to recognize a peptide from the virus called NQK-Q8. This protein building block also occurs in a similar form as NQK-A8 in the common cold coronaviruses. HLA-B15 does indeed appear to mediate the cross-immunity suspected in some people at the beginning of the pandemic.
Illustration: With HLA-B15, people are well prepared for Sars-CoV-2. : Vanette Tran
In their study, Hollenbach and colleagues were able to access the data of around 30,000 bone marrow donors. At the beginning of the pandemic, these donors also installed the “Covid-19 Citizen Science Study” app developed by the University of San Francisco. Around 1,428 of these people had a positive test for a corona infection at least once between February 2020 and April 2021, i.e. before the introduction of the vaccination.
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Of these, 136 people remained symptom-free for at least two weeks despite a positive test. Around 20 percent of these people carried at least one gene variant that produced HLA-B15. Among those who got a symptomatic infection, only 9 percent carried the gene. Those who carried at least two gene variants for HLA-B15 had an overall eight-fold reduced risk of developing symptomatic disease.
At the same time, this mutation seems to balance out known risk factors such as obesity, previous illnesses or old age. “If you have an army that is able to identify the enemy early on, that’s a big advantage,” says Jill Hollenbach, explaining the observed effects. “It’s like having soldiers prepared for battle who already know who the bad guys are.”
Hollenbach et al.: A common allele of HLA is associated with asymptomatic SARS-CoV-2 infectionnature
This topic in the program:MDR TELEVISION | Sachsenspiegel | July 18, 0023 | 7:06 p.m
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