New Delhi: Scientists have discovered a new virus similar to SARS-CoV-2 in a Russian bat that can infect humans and is resistant to currently available vaccines.
In a research paper published Thursday in the journal PLOS Pathogens, researchers from Washington State University said the virus, known as ‘Khosta-2’, comes under a sub-category of coronaviruses called sarbecovirus — the same category to which SARS-CoV-2 belongs.
The discovery highlights the need to develop universal vaccines against sarbecoviruses to protect the human population against future Covid-like pandemics, the researchers point out.
Sarbecoviruses are respiratory viruses that frequently undergo recombination — a process of viral strains mixing to make a new strain.
Researchers from the Washington State University in the US first discovered the virus in Russian bats in late 2020.
The team had identified two new viruses and named them Khosta-1 and Khosta-2. They determined that while Khosta-1 didn’t pose much threat to humans, Khosta-2 demonstrated some troubling traits.
Although the virus initially appeared to pose no threat to humans, when they looked more closely, they were “really surprised to find they could infect human cells”, Michael Letko, WSU virologist and one of the authors of the study, said in a press statement.
The team also found that Khosta-2 was resistant to both the monoclonal antibodies and serum from individuals vaccinated against SARS-CoV-2.
“Genetically, these weird Russian viruses looked like some of the others that had been discovered elsewhere around the world, but because they did not look like SARS-CoV-2, no one thought they were really anything to get too excited about,” Letko, a virologist at WSU, said in the statement.
Although hundreds of sarbecoviruses have been discovered in recent years — predominantly in bats in Asia — the majority are incapable of infecting human cells, the team said.
“That changes a little bit of our understanding of these viruses, where they come from, and what regions are concerning,” Letko said.
“Our research further demonstrates that sarbecoviruses circulating in wildlife outside of Asia — even in places like western Russia where the Khosta-2 virus was found — also pose a threat to global health and ongoing vaccine campaigns against SARS-CoV-2,” Letko said.
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Virus evades vaccines and antibodies
The research team found that like SARS-CoV-2, Khosta-2 can use its spike protein to infect cells by attaching itself to a receptor protein called ‘angiotensin converting enzyme 2’ (ACE2), found throughout human cells.
They next set out to determine if the current vaccines protect against the new virus.
Researchers used serum derived from human populations vaccinated for Covid-19 for the study and discovered that existing vaccines didn’t neutralise Khosta-2.
They also tested the serum from people who had been infected with the Omicron variant but found those antibodies, too, were ineffective.
“Right now, there are groups trying to come up with a vaccine that doesn’t just protect against the next variant of SARS-2 (SARS-CoV-2) but actually protects us against the sarbecoviruses in general,” Letko said.
“Unfortunately, many of our current vaccines are designed [for] specific viruses we know infect human cells or those that seem to pose the biggest risk to infect us. But that’s a list that’s ever-changing. We need to broaden the design of these vaccines to protect against all sarbecoviruses,” added Letko.
Even as the team highlighted the need to develop universal vaccines to protect against sarbecoviruses in general, it added that there’s no need to panic just yet.
It said that currently, the virus lacks some of the genes believed to be involved in pathogenesis — that is, developing into a disease — in humans.
That, however, doesn’t preclude the risk of the virus recombining with a second virus, like SARS-CoV-2 to evolve into a potentially deadly strain, the researchers said.
“When you see SARS-2 (SARS-CoV-2) has this ability to spill back from humans and into wildlife, and then there are other viruses like Khosta-2 waiting in those animals with these properties we really don’t want them to have, it sets up this scenario where you keep rolling the dice until they combine to make a potentially riskier virus,” Letko said.
(Edited by Uttara Ramaswamy)
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