After Covid-19 should we be worried about the Khosta-2 virus? What you need to know

Researchers from the United States have reported a bat virus, called Khosta-2, which can use the human ACE-2 receptors to enter cells just like Sars-CoV-2 that led to the Covid-19 pandemic. While these findings are from laboratory-based studies, what has the scients worried is that in case of a spillover event – a virus jumping from one species to another – it might be able to effectively infect humans.
What is the Khosta-2 virus?
The Khosta-2 virus belongs to the Sarbecovirus family, just like Sars-CoV-1 that led to the 2003 SARS outbreak and Sars-CoV-2 that led to the current pandemic. It was identified in horse-shoe bat samples from Sochi National Park. A phylogenetic analysis – a study of the virus’ family tree – showed that it is closely linked to another Sarbecovirus found in Bulgaria in 2008.
Although at first look, the receptor binding domain — the part of the virus that attaches to a human or animal receptor like a key in a lock to enter a cell – looks different from Sars-CoV-1 and 2, the researchers through various experiments established:
1. The receptor binding domain (RBD) of Khosta-2 can facilitate entry into human cells
2. The RBD uses the ACE-2 receptors just like the Covid-19 virus to enter human cells

Should we be worried about a new Coronavirus?
Finding a new Coronavirus, however, is not unusual or alarming. (Remember NeoCoV that was discovered in January this year? While it alarmed people, the researchers had demonstrated that it could not effectively use the human receptors to cause infection.)
Why the scients are concerned about this particular virus is that across several laboratory studies, the virus demonstrated that it is capable of using the Angiotensin-Converting Enzyme 2 (ACE-2) receptors found across the human body – predominantly in the respiratory and the gastrointestinal tract — to enter cells just like the Covid-19 virus.
Can it cause infection in humans?
That is the worry. Although initially thought to be not much of a threat to human beings, with the researchers from Washington State University demonstrating that the virus is capable of infecting human cells, contact between man and the animal may result in a spillover event.
“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,” the findings 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,” Michael Letko, the corresponding author and a virolog at Washington State University, said in a release.
He said, with Sars-CoV-2 having the ability to spill back from humans to wildlife and viruses like Khosta-2 waiting in those animals, “it sets up this scenario where you keep rolling the dice until they combine to make a potentially riskier virus.”
Dr Raman Gangakhedkar, former head of epidemiology and communicable diseases at Indian Council of Medical Research, in the Indian Express’ ‘Doctor, I have a question’ column, had raised similar issues of Sars-CoV-2 jumping back and forth across species till it is no longer Sars-CoV-2.

He said, “For Sars-CoV-2 there is sufficient evidence to show reverse zoonosis (spreading back to animals from humans). The virus continues to have reservoirs in animals – even household rodents – so the possibility of transmission back to humans can never be ruled out. That will, however, lead to different mutations that could be beyond Sars-CoV-2.”
Can the available vaccines protect us in case there is a spillover event?
It is unlikely. Once the researchers discovered that the virus had the capability to infect human cells, they looked at whether the currently available vaccines and monoclonal antibodies could be effective against the virus and found that there was “little cross reactivity” between Sars-CoV-2 and Khosta-2 RBD.
An experiment with the Sars-CoV-2 specific monoclonal antibody Bamlanivimab effectively neutralised virus particles with the COVID-19 spikes but not those with Khosta spikes (the RBD resides in the dinct crown-like spikes of coronaviruses).
When the researchers used the serum of people, who had received two doses of either the Pfizer or Moderna vaccine, they found that the wild type original Sars-CoV-2 was easily inhibited but not the Khosta-2. (To be sure, the current Omicron variants have drifted far away from the original Wuhan variant and the original vaccines aren’t that effective in preventing an infection.)
“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 Letko in a release.
He said, “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 Sarbecoviruses in general. 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 l that is ever-changing. We need to broaden the design of these vaccines to protect against all Sarbecoviruses.”