A new coronavirus found in Russian bats has scientists calling for an urgent effort at widespread vaccine development. Otherwise, they warn, another pandemic could be triggered by a deadly animal virus spreading to humans.
Like SARS-CoV-2, the new respiratory virus discovered among bats, known as Khosta-2, is covered in spike proteins that can infect human cells using the same entry pathways.
Even more problematic is its apparent resistance to monoclonal antibodies and serum induced in COVID-19 vaccine recipients.
In other words, this new respiratory virus cannot be neutralized by our current medications.
Not even antibodies developed from the omicron variant were effective against the bat virus, despite the fact that both pathogens belong to the same group of acute respiratory coronaviruses, known as sarbecoviruses.
“Our findings critically highlight the urgent need to continue the development of new and more broadly protective sarbecovirus vaccines,” the authors write.
When researchers in Russia first stumbled upon Khosta-2 along with another bat virus, Khosta-1, in 2020, neither pathogen seemed particularly dangerous.
None were closely related to SARS-CoV-2. In fact, they came from a different lineage that lacked some of the genes that the researchers thought were necessary to antagonize the human immune system.
However, upon closer examination, experts have identified some worrying features in Khosta-2.
In the lab, this bat pathogen was able to use angiotensin-converting enzyme 2 (ACE2) receptors on human liver cells to infect tissue in the same way as SARS-CoV-2. The receptor-binding domains in their spike proteins also showed complete resistance to monoclonal antibodies triggered by the COVID-19 vaccine.
“Genetically, these strange Russian viruses resembled some of the others that had been discovered in other parts of the world, but because they didn’t resemble SARS-CoV-2, no one really thought they were anything to get too excited about.” , Explain. virologist Michael Letko of Washington State University.
“But when we looked at them more, we were very surprised to find that they could infect human cells. That changes our understanding of these viruses a bit, where they come from and which regions are of concern.”
Khosta-2 was found in Russia’s Sochi National Park among lesser horseshoe bats (Rhinolophus hipposideros), which is a species also found in Europe and North Africa.
It’s not yet clear whether the virus infecting these bats can spread to humans in the real world, but initial findings in the lab suggest it certainly is.
If the Khosta-2 virus co-infects a host with another coronavirus, there is even a chance that the two viruses will recombine into an entirely new variant.
While Khosta-1 was unable to infect human cells on its own in the lab, when a protein-eating enzyme was artificially added to the scene, the virus was able to suddenly enter human cells using a different gate.
“[T]These findings collectively suggest that some coronaviruses can infect human cells through a currently unknown receptor,” the authors write.
“Sarbecoviruses have been shown to co-circulate in bats, so this variation in receptor usage between closely related viruses may even represent an evolutionary strategy for viral persistence within the reservoir host population.”
Obviously, that’s not a good thing. If this viral reservoir spreads to humans, our current coronavirus vaccines that primarily target the ACE2 receptor may no longer prevent infection.
In the laboratory, when receptor-binding domains in a SARS-CoV-2 virus were replaced with Khosta-2-binding domains, serum from vaccinated people was less effective at neutralizing the pseudovirus.
“Right now, there are groups trying to find a vaccine that not only protects against the next variant of SARS-2, but actually protects us against sarbecoviruses in general,” says Letko.
“Unfortunately, many of our current vaccines are designed for specific viruses that we know infect human cells or those that seem to pose the greatest risk of infecting us. But that’s a constantly changing list. We need to broaden the design of these vaccines to protect against all of them.” the sarbecoviruses.
The faster we do it, the better chance we have of stopping another deadly coronavirus outbreak.
The study was published in PLoS Pathogens.
Source: www.sciencealert.com