PULLMAN, Wash. — A team lead by Washington State University's (WSU) Paul G. Allen School for Global Health found that spike proteins from the bat virus (Khosta-2,) can infect human cells and resist SARS- CoV-2 (COVID-19) vaccines.
Both Khosta-2 and COVID-19 belong to the same sub-category of coronaviruses known as sarbecoviruses.
"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,” WSU Virologist Michael Letko said in a statement.
Letko said the discovery of Khosta-2 highlights the need to develop universal vaccines to protect against sarbecoviruses in general, rather than just against known variants of SARS-CoV-2.
“Right now, there are groups trying to come up with a vaccine that doesn't just protect against the next variant of SARS-2 but actually protects us against the sarbecoviruses in general,” Letko said.
Sarbecoviruses have been discovered in recent years, predominantly in bats in Asia. The Khosta-1 and Khosta-2 viruses were discovered in Russian bats in late 2020, and it initially appeared they were not a threat to humans.
“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 said.
Letko said when researchers looked more into these viruses, they found these viruses could infect human cells.
"That changes a little bit of our understanding of these viruses, where they come from and what regions are concerning," Letko said.
Letko teamed with a pair of WSU faculty members to study the two newly discovered viruses. They determined Khosta-1 posed low risk to humans, but Khosta-2 demonstrated some troubling traits.
According to the study, the team found that 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 throughout human cells.
Next, they set out to determine if current vaccines protect against the new virus by using serum derived from human populations vaccinated for COVID-19.
The team saw that Khosta-2 was not neutralized by current vaccines. They also tested serum from people who were infected with the omicron variant, but the antibodies, too, were ineffective.
Letko said the new virus is lacking some of the genes believed to be involved in pathogenesis in humans. There is a risk, however, of Khosta-2 recombining with a second virus like SARS-CoV-2.
“When you see SARS-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.
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