Novel COVID-like virus in Russian bats shows resistance to vaccine antibodies: ScienceAlert

A novel coronavirus found in Russian bats is prompting scientists to call for an urgent effort in widespread vaccine development. Otherwise, they warn, another pandemic could be triggered by a deadly animal virus spreading to humans.

Similar to SARS-CoV-2, the new respiratory virus discovered in bats, known as Khosta-2, is covered in advanced proteins that can infect human cells using the same inputs.

Even more problematic is its apparent resistance to monoclonal antibodies and serum induced in recipients of the COVID-19 vaccine.

In other words, this new respiratory virus cannot be neutralized by our current drugs.

Even antibodies developed from the omicron variant were not effective against the bat virus, despite the fact that both pathogens belong to the same group of acute respiratory coronaviruses, called sarbecoviruses.

“Critically, our findings highlight the urgent need to pursue the development of novel sarbecovirus vaccines with broader protection,” the authors write.

When Russian researchers first came across Khosta-2 along with another bat virus, Khosta-1, in 2020, none of the pathogens seemed particularly dangerous.

Neither was closely linked to SARS-CoV-2. In fact, they came from a separate lineage that lacked some of the genes researchers thought were necessary to antagonize the human immune system.

Upon closer examination, however, experts have identified some disturbing traits in Khosta-2.

In the laboratory, this bat pathogen was able to use angiotensin-converting enzyme 2 (ACE2) receptors on human liver cells to infect tissue in much the same way as SARS-CoV -2. Receptor-binding domains on its spike proteins also showed complete resistance to monoclonal antibodies triggered by the COVID-19 vaccine.

“Genetically, these weird Russian viruses looked like some of the others that had been discovered elsewhere in the world, but because they didn’t look like SARS-CoV-2, no one thought they were really anything to get too excited about.” , says virologist Michael Letko of Washington State University.

“But when we looked at them further, we were really surprised to find that they could infect human cells. That changes our understanding of these viruses quite a bit, where they come from and which regions are of concern.”

Khosta-2 was found in Sochi National Park in Russia among lesser horseshoe bats (Rhinolophus hipposideros), which is a species also found in Europe and North Africa.

It’s not yet known whether the virus that infects these bats can spread to humans in the real world, but early findings in the lab suggest it certainly can.

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 suddenly able to enter human cells using a different door.

“[T]These findings collectively suggest that certain coronaviruses can infect human cells via a currently unknown receptor,” the authors write.

“Sarbecoviruses have been shown to co-circulate in bats, so this variation in receptor usage among 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 spills over into humans, our current coronavirus vaccines, which primarily focus on the ACE2 receptor, may no longer prevent infection.

In the laboratory, when the receptor binding domains of a SARS-CoV-2 virus were replaced with Khosta-2 binding domains, serum from vaccinated individuals 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,” Letko said.

“Unfortunately, many of our current vaccines are designed for specific viruses that we know infect human cells or those that appear to pose the greatest risk of infecting us. But this is an ever-changing list. We need to expand the design of these vaccines to protect against all sarbecoviruses.”

The sooner we do this, the more likely we are to fend off another deadly coronavirus outbreak.

The study was published in PLoS Pathogens.

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