IThis is the news that public health experts have been expecting but dreading: Virus hunter researchers have discovered a new bat coronavirus that could spell trouble for the human population. The virus can infect human cells and is already able to bypass immune protection from vaccines against COVID-19.
Reporting in diary PLoS Pathogensscientists led by Michael Letko, an assistant professor at Washington State University’s Paul Allen School of Public Health, discovered a group of coronaviruses similar to SARS-CoV-2 that were originally discovered living in bats in Russia in 2020. At the time , scientists do not think the virus, called Khosta-2, poses a threat to humans.
But when Letko’s team did a closer analysis, they found that the virus could infect human cells in the lab, the first warning sign that it could become a possible threat to public health. A related virus also found in Russian bats, Khosta-1, cannot easily enter human cells, but Khosta-2 can. Khosta-2 binds to the same protein, ACE2, that SARS-CoV-2 uses to enter human cells. “Receptors on human cells are how viruses enter cells,” says Letko. “If the virus can’t get through the door, then it can’t get into the cell, and it’s hard to detect any kind of infection.”
Khosta-2 does not appear to have this problem as it appears to easily infect human cells. Even more alarming, when Letko combined serum from people vaccinated against COVID-19 with Khosta-2, the antibodies in the serum did not neutralize the virus. The same thing happened when they combined the Khosta-2 virus with serum from people who had recovered from Omicron infections.
“We don’t want to scare anyone and say this is a completely vaccine-resistant virus,” Letko says. “But it is worrying that there are viruses circulating in nature that have these properties – they can bind to human receptors and are not as neutralized by current vaccine responses.”
The good news is that Letko’s studies show that, like the Omicron variant of SARS-CoV-2, Khosta-2 does not appear to have the genes to suggest that it can cause serious disease in humans. But that could change if Khosta-2 begins to circulate more widely and mixes with genes from SARS-CoV-2. “One of the things we worry about is that when related coronaviruses get into the same animal and into the same cells, they can recombine and a new virus comes out,” Letko says. “The concern is that SARS-CoV-2 could spread back to animals infected with something like Khosta-2, recombine and then infect human cells. They can be resistant to vaccine immunity and also have some more virulent factors. What are the odds of that, who knows. But in theory it could happen during a recombination event.
It’s a sobering reminder that pathogens are ready and waiting to jump from any number of animal species into humans. And in many cases, as with SARS-CoV-2, these microbes will be new to humans and therefore encounter little resistance in the form of immunity against them. “These viruses are really widespread everywhere and will continue to be a problem for people in general,” Letko says.
The findings come from the ACT Working Group of the World Health Organization (WHO) Accelerator Council to Track and Accelerate Progress. report that the ongoing response to the COVID-19 pandemic, in the form of testing, vaccinations and treatments, is halting. With lower global immunity to the current SARS-CoV-2 virus, the fight against any new pathogens, including new coronaviruses such as Khosta-2, will become more difficult. According to the latest data collected by the WHO, a quarter of the world’s people have not yet received the primary series of vaccinations against COVID-19.
Ultimately, having a deeper record of the microbial world, especially information about how well certain viruses can infect human cells, for example, will be important to making the response to public health threats more efficient and powerful . Letko is working on building a database that includes information about which human receptors viruses use to infect cells, and whether or not these viruses can evade existing vaccines. That way, he says, when new microbes are discovered that are similar to those in the database, researchers could have a head start on understanding how to control them. “At some point in the future, as long as these outbreaks continue, we won’t have to fight every time a new virus spreads in humans,” he says. “We could plug the virus into the database and find out that it probably uses these receptors to get into human cells, and it might be resistant to these kinds of vaccines or treatments.” This is a 10 to 20 year goal, but it is possible. This is not just a pipe dream.”
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