When SARS-CoV-2 – the virus behind COVID-19 – showed up in China and quickly brought the entire world to a standstill, then-President Donald Trump liked to call it “the Chinese virus”.
Fast forward two and a half years, and US scientists are warning that a newly discovered virus housed by Russian horseshoe bats may also infect humans and evade COVID-19 antibodies and vaccines.
The bat virus, called Khosta-2, is known as a sarbecovirus — the same subcategory of coronaviruses as SARS-CoV-2 — and exhibits “disturbing properties,” according to a new study published in the journal PLoS Pathogens.
A team led by researchers from the Paul G. Allen School for Global Health at Washington State University (WSU) found that Khosta-2 can use its spike proteins to infect human cells, much like SARS-CoV-2 does. .
“Our research further shows that sarbecoviruses circulating in wildlife outside 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,” Michael Letko, a virologist at WSU and corresponding author of the study, said in a statement.
He said this discovery highlights the need to develop new vaccines that not only target known variants of SARS-CoV-2, such as Omicron, but protect against all sarbecoviruses.
‘Strange Russian viruses’
Of the hundreds of sarbecoviruses discovered in recent years, most have been found in Asian bats and are unable to infect human cells.
The Khosta-1 and Khosta-2 viruses were discovered in bats near Russia’s Sochi National Park in 2020, and initially appeared not to pose a threat to humans, according to the study authors.
“Genetically, these strange Russian viruses resembled some of the others discovered elsewhere in the world, but because they didn’t resemble SARS-CoV-2, no one really thought they were anything to get too excited about,” Letko said. .
“But when we looked more closely at it, we were really surprised to find that they could infect human cells. That changes a little bit of our understanding of these viruses, where they come from and what regions they are in.”
Letko and his colleagues determined that Khosta-1 posed a low risk to humans, but Khosta-2 was more concerning.
In particular, like SARS-CoV-2, Khosta-2 can use its spike protein to infect cells by attaching to a receptor protein called angiotensin-converting enzyme 2 (ACE2), which is found in human cells. .
The scientists then wanted to know whether the virus could evade the immunity afforded by previous coronavirus infections or COVID-19 vaccines.
Using serum taken from people vaccinated against COVID-19, the team found that Khosta-2 was not neutralized by current vaccines.
They also tested serum from people infected with the Omicron variant, but the antibodies were also ineffective there.
Fortunately, the authors write that the new virus lacks some of the genetic features thought to “antagonize” the immune system and contribute to disease in humans — but there is a risk that Khosta-2 could cause harm by recombining with a second virus. such as SARS-CoV-2.
“If you see that SARS-2 has this ability to flow back from humans to wildlife, and then there are other viruses like Khosta-2 waiting in those animals with these traits that we really don’t want them to have, it puts this on a scenario where you keep rolling the dice until they combine to form a potentially riskier virus,” Letko said.