A new coronavirus has been discovered, and it may have jumped to humans from dogs.
In a new study, researchers detected a new canine coronavirus in a swab sample obtained from a Malaysian child diagnosed with pneumonia in 2018. If the virus is confirmed to cause disease in humans, it would be the eighth-known human coronavirus and the first to have originated in dogs, the researchers said.
However, the study, published Thursday (May 20) in the journal Clinical Infectious Diseases, can't prove whether the canine coronavirus caused the child's pneumonia or whether another microbe was the cause — the child was also found to be infected with rhinovirus, a virus that causes the common cold in people. And even if the canine virus did cause this patient's illness three years ago, it's unclear if this coronavirus, which is genetically similar to other dog coronaviruses, can spread between people.
"How common this [canine] virus is, and whether it can be transmitted efficiently from dogs to humans or between humans, nobody knows," Dr. Gregory Gray, a professor of medicine, global health and environmental health at Duke University, and senior author of the study, said in a statement.
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But the researchers say their findings underscore the threat of animal coronaviruses to people, a risk that has become all the more clear in light of the COVID-19 pandemic, caused by the coronavirus SARS-CoV-2. (The origins are SARS-CoV-2 are still unclear, but one leading theory is that it hopped from bats to an intermediate, yet-to-be-determined animal and then to people.)
"These coronaviruses are likely spilling over to humans from animals much more frequently than we know," Gray said. "We are missing them because most hospital diagnostic tests only pick up known human coronaviruses."
The researchers originally set out to develop a diagnostic test that could detect many different types of coronaviruses, not just SARS-CoV-2, NPR reported . To evaluate their test, they used it to analyze 301 samples collected in 2017 and 2018 from hospitalized patients with pneumonia in Sarawak, Malaysia.
They found that eight of the 301 samples tested positive for the new canine coronavirus. The findings were so surprising that the researchers initially thought they had made a mistake.
"I thought, 'There's something wrong.' … Canine coronaviruses were not thought to be transmitted to people. It's never been reported before," study co-author Dr. Anastasia Vlasova, a virologist and assistant professor at Ohio State University's College of Veterinary Medicine, told NPR.
So the researchers re-tested the eight samples using a different method — they attempted to grow the virus in canine cells using a method that works well for dog coronaviruses, NPR reported. One of the samples grew in the canine cells, and the researchers were able isolate the virus and sequence its genome.
They confirmed that the virus, which they dubbed CCoV-HuPn-2018, is a new canine coronavirus. The virus also contains segments of genetic material from cat and pig coronaviruses — a phenomenon known as recombination that is commonly seen in dog coronaviruses. The finding suggests this virus also infected cats and pigs in the past, The New York Times reported.
Interestingly, the new canine coronavirus also has a mutation that has not been seen in any dog coronaviruses before, but similar mutations have been seen in SARS-CoV-2 and SARS-CoV-1, the virus that causes severe acute respiratory syndrome or SARS. This mutation occurs in one of the virus's structural proteins known as the N protein.
The implications of this mutation are unclear, but it's possible it helps animal coronavirus adapt to infect people.
The researchers plan to conduct more studies to see how common canine coronavirus infections in humans are, and if these viruses can be found in healthy as well as sick people, the Times reported.
Originally published on Live Science.