HealthDay News — A novel human coronavirus (hCoV-EMC) identified earlier this year in the Middle East does not use the same receptor as the deadly 2003 SARS virus, researchers found.

The new virus appears to be able to infect a wide range of mammalian cells, including humans, bats and pigs, Christian Drosten, MD, of the University of Bonn Medical Center in Bonn, Germany, and colleagues reported in mBio.

Because of the similar genetic properties and the ability of both viruses to cause respiratory illness with renal failure, the researchers set out to determine whether hCoV-EMC uses the SARS coronavirus receptor angiotensin-converting enzyme 2 (ACE2). 

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Because the ACE2 receptor is found deep in the human respiratory tract, large doses of SARS were necessary to cause disease — leading to more aggressive disease, quicker hospital admissions and isolation — factors which health officials believe helped limit the spread of SARS.

Results from experiments comparing hCoV-EMC and SARS-CoV, revealed that ACE2 is neither necessary nor sufficient for replication of hCoV-EMC. In addition, hCoV-EMC, but not SARS-CoV, could replicate in cells from Rousettus, Rhinolophus, Pipistrellus, Myotis and Carollia bats.

Researchers called this finding “remarkable,” because coronaviruses typically cannot be transmitted back to their original reservoir after adapting to spread in humans.

“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,” the researchers concluded.

As of Nov. 30, the World Health Organization has confirmed nine cases of hCoV-EMC — two in people from Qatar, five in residents of Saudi Arabia and two in Jordan. Five of the cases have resulted in deaths.

There is some evidence of human-to-human transmission, as three cases occurred in Saudi family members who lived together, according to WHO.

Drosten and colleagues were unable to determine which receptor hCoV-EMC uses, but they noted that it must be present in all three types of mammals.

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