A new coronavirus discovered in Russian bats has prompted scientists to call for urgent efforts to make a vaccine available. Otherwise, it warns that another pandemic could be triggered by a deadly animal virus infecting humans.
Similar to SARS-CoV‑2, a new respiratory virus found among bats called Khosta‑2 is coated with a spike protein and can use the same entry route to infect human cells. increase.
Even more problematic is the apparent resistance to monoclonal antibodies and sera induced in COVID-19 vaccinees.
This means that this new respiratory virus cannot be neutralized by existing drugs.
Even antibodies developed from omicron mutants were ineffective against bat viruses, even though they are in the same group of acute respiratory coronaviruses (sarbecoviruses).
“These results highlight the urgent need to develop new sarbecovirus vaccines with broader protection,” the authors wrote.
When Russian researchers first encountered Khosta‑2 and another bat virus, Khosta‑1, in 2020, neither pathogen seemed particularly dangerous.
Neither were closely related to SARS-CoV‑2. The gene actually came from a different lineage that lacked some of the genes researchers thought were necessary to antagonize the human immune system.
But upon closer inspection, experts have confirmed that Khosta‑2 has some worrisome features.
In the lab, the bat pathogen was found to infect tissues in much the same way as SARS-CoV‑2, utilizing the angiotensin-converting enzyme 2 (ACE2) receptor on human liver cells. Also, the receptor-binding domain of its spike protein exhibited complete resistance to monoclonal antibodies induced by the COVID-19 vaccine.
Virologist Michael Letko of Washington State University said, “Genetically, this strange Russian virus was similar to other viruses found in other parts of the world. But SARS-CoV‑2 has It didn’t look like it, so no one thought this virus was really exciting.”
“However, upon further study, we were very surprised to find that they infect human cells. It’s going to change a little bit.”
Khosta‑2 was discovered in the Sochi National Park, Russia, among the small bat (Rhinolophus hipposideros), which is also found in Europe and North Africa.
It is not yet clear whether these bat-infecting viruses will infect humans in the real world, but early results in the lab suggest it is certainly possible.
If the Khosta‑2 virus infects other coronaviruses, it is even possible that the two viruses combine to form an entirely new virus.
In the lab, Khosta‑1 could not infect human cells on its own, but when the protein-eating enzyme was artificially added, the virus was suddenly able to enter human cells through another gateway.
“These findings suggest that some coronaviruses infect human cells through a currently unknown receptor,” the authors write.
“Since Salvedoviruses have been shown to co-circulate in bats, differences in how these receptors are used among closely related viruses may contribute to their persistence in reservoir host populations. It could even be an evolutionary strategy.”
obviously bad. Current coronavirus vaccines, which primarily target the ACE2 receptor, may not be able to prevent infection if this viral reservoir spreads to humans.
The lab found that replacing the receptor-binding domain of the SARS-CoV‑2 virus with a Khosta-2-binding domain made the sera of vaccinees less effective at neutralizing the pseudovirus.
“There are groups now trying to create a vaccine that not only protects against the next SARS‑2 variant, but against Salvec virus in general,” says Letko.