New SARS-related virus an effective infector, study shows
A new coronavirus found in 12 patients worldwide can infect people's respiratory tracts as easily as SARS or the common cold, a new study shows.
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A new coronavirus found in 12 patients worldwide can infect people’s respiratory tracts as easily as SARS or even the common cold, according to a study published Tuesday.
But at the same time, the virus — which still cannot spread easily from person to person — is susceptible to immunotherapy, “providing a possible avenue for treatment,” the study’s authors say.
“These are things that needed to be demonstrated,” said microbiologist Dr. Malik Peiris with the University of Hong Kong, a leading SARS and coronavirus expert who was not involved with the study. “It can have important implications.”
Little is known about the novel coronavirus, which first emerged in the Middle East and belongs to the same viral family as SARS. The virus has infected a dozen people since April 2012 — five of them fatally — and can cause severe pneumonia and kidney failure.
The virus likely comes from bats but no one knows how — or when — it crossed into humans. In a paper published in the scientific journal mBio, researchers used cell cultures to test how easily the virus penetrates the lining of the entryways into the lung — “an important first barrier” against viral invaders.
“Is it just a wimpy virus on those cells? Or is it just as good as viruses known to replicate very well?” asked Dr. Volker Thiel, one of the paper’s two lead authors, who works at the Kantonal Hospital’s Institute of Immunology in Switzerland. “We found that it’s very similar to SARS coronavirus and also to a very common cold virus. So that tells us that the virus can easily replicate in these cells.”
The coronavirus is still not adept at spreading from person to person. But Thiel said his study suggests it is already well adapted to humans, despite having only recently jumped over from another species.
And once the virus takes hold inside the airways, it multiplies even faster than SARS, his study found.
Just like SARS and other coronaviruses, the virus knows how to sneak past the immune system, the study showed. It does this by suppressing interferons, which are proteins sent out by infected cells to signal danger and trigger an antiviral attack.
For coronaviruses, this is their “stealth mechanism” — it allows them to infect while staying under the radar, according to Peiris. “This provides one explanation why these coronaviruses are successful at infecting humans,” he said.
But the researchers also found another similarity to SARS that exposes a possible weakness in the virus: although it initially blocks interferons, it can also be weakened by them.
“The good news is this virus is not different to other coronaviruses in terms of its vulnerability to interferons,” Thiel said. “Interferon treatment should work — to some extent, at least,” Thiel said.
Thiel said interferon treatment has shown potential for SARS, although drug development stopped once the outbreak ended. He estimated it would take at least a decade to develop drugs for this new coronavirus.
Dr. Matthew Frieman, a microbiologist with the University of Maryland who was not involved with the study, said he was unsurprised by the paper’s findings.
Coronaviruses have several proteins that block the immune system’s ability to detect them, he said. The flu — a less complex virus — only has one of these proteins; SARS has at least six, said Frieman, who is also now studying the new coronavirus.
“It looks like it doesn’t matter if (the coronavirus) is in bats or civet cats or humans — these proteins work the same,” he said. “So they’ve probably evolved to be very general in their abilities.”
Thiel said basic information is still needed on the novel coronavirus; scientists don’t know how people are getting infected, for example. Malik said researchers should also now determine whether the virus can infect the nose and throat — as the common cold virus does — or deep inside the lungs, which would explain why it causes such severe pneumonia.
There is still no need to panic over the novel coronavirus, he said. Compared to the seasonal flu or other viruses, its impact thus far has been small.
“It’s just 12 cases,” he said. “I think here we have to stay rational . . . It’s certainly not frightening at the moment.”
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