New Coronavirus Discovered in China, What It Is and What We Risk

“Merbecoviruses from bats present a high risk of spreading to humans, both through direct transmission and through intermediate hosts”: this is the assumption behind the discovery made by virologist Shi Zhengli , known as 'batwoman' for her in-depth research on bat coronaviruses, at the Guangzhou laboratory, together with researchers from the Guangzhou Academy of Sciences, the University and the Institute of Virology of Wuhan. We are talking about a new bat coronavirus that can pass from animals to humans because it uses the same human receptor as the virus that causes Covid. It is called HKU5 and was first identified in a Japanese bat in Hong Kong: it comes from the merbecovirus subgenus, which also includes the Mers-CoV virus that causes Middle East Respiratory Syndrome (Mers). But what does this discovery reveal? And what should we expect?

How Covid Passed to Humans

While there is still no consensus on the origin of Covid, some studies have suggested an initial link in bats and that it passed to humans via an intermediate animal host. At the same time, Shi denied that the Wuhan institute could have been responsible for the pandemic.

This latest discovery brings to light a new lineage of the HKU5 coronavirus first identified in the Japanese bat in Hong Kong: it comes, in fact, from the subgenus of the merbecovirus. It is able to bind to the human angiotensin-converting enzyme, the same receptor used by the Sars-CoV-2 virus, which causes Covid, to infect cells.

“We report the discovery and isolation of a distinct lineage (lineage 2) of HKU5-CoV, which can utilize not only bat Ace2, but also human Ace2 and several mammalian Ace2 orthologues (genes found in different species with a common origin),” the researchers wrote in a paper published in the journal Cell .

Can infect human cells

All of this highlighted the fact that the virus, once isolated from bat samples, could infect human cells and artificially cultured cell masses or tissues that resembled miniaturized respiratory or intestinal organs.

In early February, Cell published a paper by a team from the University of Washington in Seattle and Wuhan University that concluded that while the HKU5 strain could bind to the ACE2 receptors of bats and other mammals, “efficient” human binding was not detected. But Shi’s team said that HKU5-CoV-2 was better adapted to human ACE2 than lineage 1 of the virus and “may have a broader host range and greater potential for cross-species infection.” The researchers said that more monitoring of the virus was needed, even though its efficiency was “significantly lower” than that of Covid, and the “risk of emergence of (HKU5-CoV-2) in human populations should not be exaggerated.”

Bats, ideal incubators of the virus

They are not the only ones to carry viruses to humans, but bats can certainly be among the ideal vectors. This was demonstrated, again in February 2022, by a discovery by the Pasteur Institute in Paris and Laos in Vientiane, published in Nature. In that case too, it emerged that the SARS-CoV-2 virus has three very close relatives: they live in bats that populate the caves of Laos and are potentially capable of infecting humans.

“Since its appearance, numerous animal species have been studied to identify possible animal reservoirs or intermediate hosts of the virus,” the researchers observed, who, following that objective, had identified in organic samples of bats captured in some limestone caves in Northern Laos three new coronaviruses, called BANAL-52, -103 and -236, very close to SarsCoV2. The similarity mainly concerned the Spike protein, especially that portion of the protein that binds to the ACE2 receptor, which is the main gateway that the virus uses to enter the cells of our body.

New coronaviruses in the British Isles

But also in June 2023, in this case in the British Isles, the discovery of new coronaviruses of the same group as Sars and one of Mers had emerged. One of the new coronaviruses isolated from the 48 stool samples examined during the work carried out by the UK researchers, a study published in Nature Communications , had on its spike a protein capable of making the leap between species, and therefore infecting humans.

In the laboratory, however, researchers had demonstrated that the affinity between this component of the new virus and the receptor present on human cells was much lower than that typical of SARS-CoV-2, so the discovered agent could only infect tissues that express ACE2 in abnormal quantities, which made it highly unlikely to infect humans.

A continuous evolution

However, the large number of viruses from the same family (sarbecoviruses) thought to be circulating in horseshoe bats (Rhinolophus hipposideros) in the UK, in addition to those already identified in the rest of Europe, suggests that the possibility of dangerous mutations exists.

By 2021, more than 4,000 coronavirus genetic sequences had been identified worldwide in 14 different bat families, but experts believe that the reservoir of infectious agents in these flying mammals with extraordinary immune systems is much larger than we can imagine today. Among these, no one can rule out that there are some capable of causing another pandemic if they come into contact with humans.

Pregliasco: “No danger, but let’s get to the bottom of it”

“Let's look at it positively, this discovery shows how important the ability to identify new variants is”. This is what virologist Fabrizio Pregliasco , medical director of the Galeazzi Sant'Ambrogio hospital in Milan, says. He continues: “The epidemiological importance of this virus is yet to be discovered, but the legacy of reporting and attention that Covid has left us is welcome. It is important for institutions and for research”.

“Zonosis, or animal diseases that can spread to humans, are the future. We see it with avian influenza that is transmitted to other species, it is the virus's option to expand its contagion range - Pregliasco recalls -. The important thing is to identify the characteristics of the pathogens, to want to look for new information. We must have a goal and this latest research, for example, allows us to identify it”.

As for bats, the virologist explains: “They are mammals that live in environmental contexts close to humans, and the virus is likely to come from Asian countries rather than Europe, because there are more specimens there and there is more proximity between humans and animals”. And he concludes: “Should we fear something? I would say no. It is not certain that this variant has the capacity to spread. The presence of a pathogen similar to the coronavirus represents a new signal, but from here to saying that it will become pandemic there is a big difference”.