A recently discovered virus in a Russian bat that resembles SARS-CoV-2, the virus behind COVID-19, is likely to be capable of infecting humans and, if it skips, is resistant to current vaccines.
A team led by researchers from Washington State University’s Paul G. Allen School for Global Health found that bat virus spike proteins, called Khosta-2, can infect human cells and are resistant to both the monoclonal antibodies and the serum. from individuals vaccinated for SARS-CoV-2. Both Khosta-2 and SARS-CoV-2 belong to the same subcategory of coronaviruses known as sarbecoviruses.
“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,” says Michael. Letko, WSU virologist and corresponding author of the study published in the journal PLoS pathogens.
Letko said the Khosta-2 discovery highlights the need to develop universal vaccines to protect against sarbecoviruses in general, rather than just known variants of SARS-CoV-2.
Right now there are groups trying to come up with a vaccine that not only protects against the next variant of SARS-2, but actually protects us against the sarbecoviruses in general. Unfortunately, many of our current vaccines are designed for specific viruses that we know infect human cells or appear to pose the greatest risk of infecting us. But that’s a list that keeps changing. We need to broaden the design of these vaccines to protect against all sarbecoviruses.”
Michael Letko, WSU virologist
Although hundreds of sarbecoviruses have been discovered in recent years, mainly in bats in Asia, the majority are unable to infect human cells. The Khosta-1 and Khosta-2 viruses were discovered in Russian bats in late 2020 and initially appeared to pose no threat to humans.
“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 teamed up with a pair of WSU faculty members, first author viral ecologist Stephanie Seifert and viral immunologist Bonnie Gunn, to study the two newly discovered viruses. They determined that Khosta-1 posed a low risk to humans, but Khosta-2 showed some troubling properties.
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 in human cells. . Next, they wanted to determine whether current vaccines protect against the new virus.
Using serum from human populations vaccinated against COVID-19, the team saw that Khosta-2 was not neutralized by current vaccines. They also tested serum from people infected with the omicron variant, but the antibodies also did not work.
Fortunately, Letko said the new virus is missing some of the genes believed to be involved in pathogenesis in humans. However, there is a risk of Khosta-2 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.
In addition to Letko, Seifert and Gunn, Shuangyi Bai and Stephen Fawcett of WSU, as well as Elizabeth Norton, Kevin Zwezdaryk and James Robinson of Tulane University, are co-authors of this study.
Washington State University
Seifert, S.N., et al. (2022) An ACE2-dependent Sarbecovirus in Russian bats is resistant to SARS-CoV-2 vaccines. PLOS pathogens. doi.org/10.1371/journal.ppat.1010828.