A new coronavirus that's been blamed for five deaths can infect a range of animals, a finding scientists say could make it harder to eliminate compared with SARS.
The coronavirus emerged in the Middle East, where there's been nine infections, including the five fatal cases since June, according to the World Health Organization.
In Tuesday's issue of the journal mBio, published by the American Society for Microbiology, German researchers describe their studies comparing the new virus, called hCoV-EMC, with SARS or severe acute respiratory syndrome. About 8,500 people were affected by SARS in 2003 and about 700 died, including 44 in Toronto.
"The virus is capable of infecting human, pig and bat cells," Christian Drosten of the University of Bonn Medical Centre and co-authors concluded.
"Our results implicate that the new virus might use a receptor that is conserved between bats, pigs and humans suggesting a low barrier against cross-host transmission."
Scientists are watching for signs of "cross-host transmission" because if the virus is able to infect cells from a range of species then it might be able to pass easily between animals and humans repeatedly. That would make it harder to stamp out.
So far, the virus causes the same pattern of disease as SARS, Drosten said.
Researchers have found no evidence of human-to-human transmission of the new virus, which they are also watching for closely to check if it could spread like wildfire. The two fatal cases were part of a cluster linked to a hospital, according to the European Centre for Disease Prevention and Control said.
The limited information available about this outbreak does not allow for an assessment of whether human-to-human transmission has occurred or indeed whether the cases in this cluster had the same cause, the agency said in a release on Monday.
The SARS virus latched onto receptors deep in the human lung, which may explain why it led to severe illness but is also thought to have limited its spread between people, the German researchers said.
Drosten's team performed a series of experiments to see whether hCoV-EMC used the same receptor in the lungs of humans and bats, which acted as a reservoir for SARS.
They concluded that the new virus does not seem to rely on the same receptor as SARS.
It's possible that the new virus could use a receptor that is easier to access, which could make it more infectious. No one knows what receptor it does use.
Like SARS, the new virus is most closely related to coronaviruses from bats. But unlike SARS, the new virus can still infect cells from many species of bats.
"This was a big surprise," Drosten said in a release. "It's completely unusual for any coronavirus to be able to do that — to go back to its original reservoir."
The virus's ability to infect multiple species in the lab might suggest that the human cases were infected by animal sources rather than people, Drosten noted.
Scientists are also on the hunt for the animal source of the virus, which could give them clues to managing a potential outbreak.
The study was funded by the European Union, Antigone, the German Research Foundation and the German Ministry of Education and Research.