Some people may be better protected against Covid-19 because of their genes, a study suggests.
But new variants of the coronavirus could still learn to evade any protection offered by these genes, scientists have warned.
Research suggested antiviral responses are better in people who have a more protective “prenylated” version of the OAS1 gene, while others have a version which fails to detect the virus.
New variants that learn to evade that genetic protection could become “substantially more pathogenic and transmissible in unvaccinated populations”, experts said.
Prenylation, the attachment of a molecule of fat to a protein, allows prenylated OAS1 to “seek out” the invading virus and “sound the alarm”, say researchers.
Patients in hospital who had a prenylated version of the gene were generally better protected from severe Covid-19, the study found, suggesting it is a “major component of a protective antiviral response”.
Researchers also found that those with the “bad” form of OAS1 experienced significantly more frequent levels of severe disease, with intensive care admission or death around 1.6 times more likely in these patients.
The study, called A prenylated dsRNA sensor protects against severe Covid-19, is published in the journal Science and was led by the MRC-University of Glasgow Centre for Virus Research.
Horseshoe bats, which are thought to be the source of Covid-19, lost this protective gene 55 million years ago, scientists say, so the coronavirus did not have to adapt to evade the defence.
Professor Sam Wilson, of the University of Glasgow’s Centre for Virus Research, said: “We know viruses adapt, and even Sars-CoV-2 has likely adapted to replicate in the animal reservoir(s) in which it circulates.
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“Cross-species transmission to humans exposed the virus Sars-CoV-2 to a new repertoire of antiviral defences, some of which Sars-CoV-2 may not know how to evade," Prof Wilson said.
“What our study shows us is that the coronavirus that caused the Sars outbreak in 2003 learned to evade prenylated OAS1.
“If Sars-CoV-2 variants learn the same trick, they could be substantially more pathogenic and transmissible in unvaccinated populations.
“This reinforces the need to continually monitor the emergence of new Sars-CoV-2 variants.”
The study was predominantly funded by the Medical Research Council, Wellcome, and UK Research and Innovation.