So you haven't caught COVID yet. Does that mean you're a superdodger?
Do some people have built-in protection against a COVID infection? Laura Gao for NPR
... ...
Other scientists had identified groups of people who appeared to be completely resistant to HIV. "People who knew they had been exposed to HIV multiple times, mainly through unprotected sex, yet they clearly were not infected," "Are these people just lucky or did they really have a mutation in their genes that was protecting them from infection?'"
Now 25 years later, scientists all over the world are trying to answer the same question but about a different virus: SARS-CoV-2.
... ...
"We've heard countless anecdotes about nurses and health-care workers, being exposed without any protection and remaining negative over and over again," says pediatrician Jean-Laurent Casanova, who studies the genetics of viral resistance at Rockefeller University. "Or people share a household with someone who's been coughing for a couple of weeks, and one person stays negative."
So why haven't these people caught COVID? .
After two years of hunting, a team at the University of California, San Francisco has come pretty close to answering the question.
"These findings are like hot off the presses," says immunogeneticist Jill Hollenbach, who led this research. "We haven't published them yet. It's all stuff that's been happening this summer.
... ...
Are there really COVID superdodgers?
For COVID superdodgers, the situation appears to be more complex than for people resistant to HIV, Landau says, because the way SARS-CoV-2 infects cells is different from that of HIV.
Instead of using CCR5 to "open the cell's door," SARS-CoV-2 uses the ACE2 receptor. People can't live without ACE2. "The receptor regulates your blood pressure," Landau explains. So, unlike CCR5, you can't simply knock out the ACE2 receptor, he says. "You're not going to have many people walking around that don't have ACE2.
"Of course, there may be more subtle mutations in ACE2 which could play a role in resistance to SARS-CoV-2," he adds. "But there doesn't seem to be an obvious and dramatic mutation as is the case for HIV."
But perhaps what's more likely, he says, is that people have mutations in genes other than ACE2, and these mutations probably don't protect them from getting infected per se but do protect them from getting sick.
So having one of these mutations would make you a sort of COVID minidodger, if you will. There are other ways to resist an infection besides denying the virus entrance into the cell, Landau explains. And they likely involve your body's immune system.
That's exactly what the team at UCSF has found.
Since the pandemic began, Jill Hollenbach and her colleagues at UCSF have been studying people who test positive COVID but show no symptoms. "Not even a sniffle or a scratchy throat," she says. "So they are entirely asymptomatic."
After analyzing DNA from more than 1,400 people, they identified a mutation that helps a person clear out SARS-CoV-2 so fast that their body doesn't have a chance to develop symptoms.
The mutation occurs in a gene called HLA, which is critical during the earliest stages of infection... ...
For full document, click on this link
中文摘要在我的blog:
选择“Disable on www.wenxuecity.com”
选择“don't run on pages on this domain”
