Newly Discovered Virus Similar to COVID Could Infect Humans and Resist Vaccines
By WASHINGTON STATE UNIVERSITY
A
team led by researchers at Washington State University’s Paul G. Allen
School for Global Health discovered spike proteins from the bat virus, known as
Khosta-2, that can infect human cells and are resistant to both monoclonal
antibodies and serum from SARS-CoV-2 vaccine recipients. Khosta-2 and
SARS-CoV-2 are both coronaviruses that belong to the same subclass 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,” said Michael Letko, WSU virologist and corresponding author of the study published in the journal PLOS Pathogens.
Letko
said that rather than just protecting against known versions of SARS-CoV-2, the
finding of Khosta-2 underscores the necessity to create universal vaccinations
to defend against sarbecoviruses in general.
“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. “Unfortunately, many of our current
vaccines are designed for 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’s
everchanging. We need to broaden the design of these vaccines to protect
against all sarbecoviruses.”
Despite
the fact that hundreds of sarbecoviruses have recently been identified, mostly
in Asian bats, the majority cannot infect human cells. In late 2020, the
Khosta-1 and Khosta-2 viruses were found in Russian bats, and at first, it
seemed they posed little danger to people.
“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. “But when we looked at them more, we were really surprised to find
they 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
teamed 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 Khosta-1 posed a low risk to humans, but
Khosta-2 demonstrated some troubling traits.
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 neutralized by current vaccines. They also tested serum from
people who were infected with the omicron variant, but the antibodies, too,
were ineffective.
Fortunately,
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.
Reference:
“An ACE2-dependent Sarbecovirus in Russian bats is resistant to SARS-CoV-2
vaccines” by Stephanie N. Seifert, Shuangyi Bai, Stephen Fawcett, Elizabeth B.
Norton, Kevin J. Zwezdaryk, James Robinson, Bronwyn Gunn and Michael Letko, 22
September 2022, PLOS Pathogens.
DOI: 10.1371/journal.ppat.1010828