Newly discovered SARS-CoV-2-like virus could infect humans and resist vaccines

A team led by researchers at Washington State University’s Paul G. Allen School for Global Health, US, have found that spike proteins from the bat virus, named Khosta-2, could infect human cells. The scientists found that the virus is likely to be resistant to both the monoclonal antibodies and serum from individuals vaccinated for SARS-CoV-2. Both Khosta-2 and SARS- CoV-2 belong to the same sub-category of coronaviruses known as sarbecoviruses. The study was recently published in PLoS Pathogens.

“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,” said Michael Letko, a corresponding author of the study.

The researchers argue 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 does not just protect against the next variant of SARS-2 but actually protects us against the sarbecoviruses in general,” Letko said. “Unfortunately, many of our current vaccines are designed to specific viruses we know infect human cells or those that seem to pose the biggest risk to infect us. But that is a list that is everchanging. We need to broaden the design of these vaccines to protect against all sarbecoviruses.”

While hundreds of sarbecoviruses have been discovered in recent years, predominantly in bats in Asia, the majority are not capable of infecting human cells. 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.

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), found throughout human cells. They next set out to determine if current vaccines protect against the new virus.

Using serum derived from human populations vaccinated for COVID-19, the team saw that Khosta-2 was not neutralised by current vaccines. They also tested serum from people who were infected with the Omicron variant, but the antibodies, too, were ineffective.

Fortunately, the scientists 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 do not 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 concluded.