A group of scientists fear they may have discovered another coronavirus capable of infecting humans. The virus has been spotted in patients suffering from pneumonia in Malaysia and likely originated from dogs. At this point, though, it’s not certain whether the virus is truly causing illness or if it could spread between people.
Even before the covid-19 pandemic began sometime in late 2019, infectious disease scientists were worried about coronaviruses. These spiky-balled pathogens infect a wide range of animals, and the experiences of SARS in 2003 and MERS in 2012 had already shown that novel coronaviruses could regularly jump from animals to people. As covid-19 has since demonstrated, the right mix of genetic changes could then allow these viruses to become a widely spread human germ.
Early on in the pandemic, researchers at Duke University and elsewhere began developing tests meant to detect all sorts of coronaviruses in our blood — both those known to infect humans and other animals already, as well as yet-unknown viruses that could pose a current or future danger to us. Now, they seem to have identified one such possible threat.
Using their new highly sensitive test, the team analysed stored nasal swab samples collected from 301 patients in Sarawak, Malaysia who were hospitalized with pneumonia between 2017 and 2018. In eight of these patients (2.7%), they found RNA traces of a canine coronavirus, though the implications of their discovery weren’t entirely clear then.
In their latest work, published Thursday in Clinical Infectious Disease, they were able to use more conventional tests to detect the virus in two of the patients. They also managed to isolate and grow the virus in the lab, allowing them to sequence its genome. Once they did, they determined that the virus was a recombined mix of a canine and feline coronavirus, which both belong to the same genus called alphacoronavirus — and that it had never been documented before.
“This is the first report of a novel canine-feline recombinant alphacoronavirus isolated from a human pneumonia patient,” the study authors wrote.
The find is nothing short of worrying, since it seems to be the first known instance of a canine coronavirus jumping the species barrier over to humans. It also seems to carry a mutation unique among canine coronaviruses but not other human coronaviruses: a deletion of genetic material in its N protein that could be allowing it to better infect us.
“Apparently the deletion is somehow associated with [the virus’s] adaptation during this jump from animal to human,” study author Anastasia Vlasova, an animal virologist at Ohio State University, told NPR.
The authors are quick to caution that they haven’t fulfilled something called Koch’s postulates, the set of criteria scientists use to confirm that a suspected infectious agent is causing illness in people. Moreover, while the people in this study were sick with pneumonia and had this virus in their bloodstream, that doesn’t necessarily mean their illness was caused by the virus. So at this point, we don’t know whether their novel virus truly is a human germ. Even if that does turn out to be the case, it wouldn’t necessarily be cause for immediate alarm. New epidemics and pandemics do spring up often from zoonotic (animal-to-human) transmission, but not all zoonotic transmissions become a major threat to our health. Right now, we don’t even know if this virus is capable of spreading between people — the leading characteristic that allowed covid-19 to become our latest pandemic.
That’s not to say this research isn’t important. If the team’s work is validated, their find would become the eighth known coronavirus pathogen in humans, as well as the fourth discovered in less than 20 years. The risk of the virus further adapting to people in a more destructive way is also absolutely worth keeping a close eye on. To that end, the researchers say that more work has to be done to find out how commonly this (and other canine coronaviruses) can be found in people, how it’s spreading, and its disease-causing potential.
“Our findings underscore the public health threat of animal CoVs and a need to conduct better surveillance for them,” they wrote.