December 11, 2012
New Coronavirus Could Have Many Hosts
Lee Rannals for redOrbit.com — Your Universe Online
According to a new study published in the journal mBio, the new coronavirus has many potential hosts and could pass from animals to humans repeatedly.
The new virus, hCoV-EMC, is blamed for five deaths and several other cases of severe disease originating in countries in the Middle East.
The new study shows hCoV-EMC uses a different receptor in the human body than the SARS virus, which caused an epidemic in 2002 through 2003. HCoV-EMC can infect cells from a wide range of bat species and pigs, indicating there may be little to keep the virus from passing from animals to humans.
Nine laboratory-confirmed cases of hCoV-EMC infection have been identified now. Although the virus does not pass from person to person very readily, the case fatality rate and the fact the source of the virus has not been identified is concerning.
"This virus is closely related to the SARS virus, and looking at the clinical picture, it causes the same pattern of disease," Christian Drosten of the University of Bonn Medical Center in Germany, a lead author of the study, said in a statement.
The researchers wanted to determine whether hCoV-EMC and SARS might use the same receptor. The SARS receptor, known as ACE2, is found on pneumocytes deep within the human lung, so an individual must breathe in many SARS viruses for a sufficient number of them to reach this area and cause an infection.
Drosten says this fact helped ensure the SARS outbreak didn't spread like wildfire and was mostly limited to healthcare workers and residents of overcrowded housing in Hong Kong.
Also, when a person is infected with SARS, he or she felt sick almost immediately and was not active in the community and infecting others. With these things taken into consideration, the researchers determined that hCoV-EMC does not use ACE2.
This leaves the possibility hCoV-EMC could use a receptor in the human lung that is easier to access and could make the virus more infectious than SARS.
The second part of the study focused on the animal species the virus can infect. SARS is closely related to a virus from bats, but Drosten said the virus changed in the transition from bats to civet cats to humans and could no longer infect bats.
The study found that like SARS, hCoV-EMC is closely related to coronaviruses from bats. However, unlike SARS, the study found hCoV-EMC can still infect cells from many different species of bats.
"This was a big surprise," Drosten said in a statement. "It's completely unusual for any coronavirus to be able to do that — to go back to its original reservoir."
The virus is able to infect cells from pigs, which indicates it uses a receptor structure that these animals have in common. If that receptor is present in mucosal surfaces, it is possible the virus could pass from animals to humans and back again.
Drosten said the work will continue in many hospitals and laboratories, and that he is driven to find the animal source of the virus, which is a crucial piece of information in managing the potential outbreak.