 than 3,000 people, two genetic variations decreased the expression of a gene called OAS1, which is part of the innate immune response to viral infections. This was associated with an increased risk of hospitalization for Covid-19.
Increasing gene expression should therefore have the opposite effect – reducing the risk of severe disease – although it would not necessarily prevent infection.
“It’s very natural to get infected once you’re exposed. There’s no magic formula for that. But after you get infected, how you’re going to react to that infection is what’s going to be affected. by your genetic variants,” said Ludmila Prokunina-Olsson, principal investigator of the study and head of the Translational Genomics Laboratory at the National Cancer Institute.
Still, Benjamin tenOever, a microbiology professor at NYU Grossman School of Medicine who helped lead the 2020 research, said it would be difficult for scientists to pinpoint a particular gene responsible for preventing an infection. Covid.
“While there may still be genes that make people completely resistant, they will be incredibly hard to find,” tenOever said. “People have already searched intensely for two years without any real results.”
T cells could remember past encounters with the coronavirus
Besides this new coronavirus, SARS-CoV-2, four other coronaviruses commonly infect people, usually causing mild to moderate upper respiratory illnesses like the common cold.
A recent study suggested that repeated exposure or occasional infections with these cold coronaviruses may confer some protection against SARS-CoV-2.
Researchers have found that T cells, a type of white blood cell that recognizes and fights invaders, appear to recognize SARS-CoV-2 based on past exposure to other coronaviruses. So when someone who has been infected with a cold coronavirus is then exposed to SARS-CoV-2, they may not get as sick.
But that T-cell memory probably can’t completely prevent Covid.
“While neutralizing antibodies are key to preventing an infection, T cells are key to ending an infection and modulating the severity of the infection,” said Alessandro Sette, study author and professor at the Institute. La Jolla of Immunology.
Sette said it’s possible that some people’s T cells clear the virus so quickly that the person never tests positive for Covid. But researchers don’t yet know if that’s what’s happening.
“It’s possible that despite the negative test result, it was a very abortive transient infection that went undetected,” Sette said.
At the very least, he said, T cells from previous Covid infections or vaccines should continue to offer some protection against coronavirus variants, including BA.5.
Allergies can lead to a little extra protection
Although asthma was considered a potential risk factor for severe Covid at the start of the pandemic, more recent research suggests that low-grade inflammation due to conditions such as allergies or asthma may have a protective effect.
“You will hear these stories of people getting sick and showing full symptoms of Covid, and having slept next to their partner for an entire week during this time without giving it to them. People think they must have some genetic resistance to it, [but] a lot of that could be if the partner next to them somehow has a higher than normal inflammatory response in their lungs,” tenOever said.
A can study found that having a food allergy halved the risk of coronavirus infection in nearly 1,400 US households. Asthma did not reduce people’s risk of infection in the study, but it did not increase it either.
One theory, according to the researchers, is that people with food allergies express fewer ACE2 receptors on the surface of their airway cells, making it harder for the virus to enter.
“Because there are fewer receptors, you’ll either have a much lower grade infection or just be less likely to get infected,” said Tina Hartert, a professor of medicine and pediatrics at Vanderbilt University School of Medicine who co-directed this research. .
The study ran from May 2020 to February 2021, before the omicron varia