February 19, 2013
New Coronavirus Strain Adapted To Humans, Replicates Faster Than SARS
Lawrence LeBlond for redOrbit.com - Your Universe Online
A new strain of coronavirus, which has already infected 12 people and killed six in the past several months, has been found to breed in the human body much faster than SARS and can evade the immune system just as easily as a common cold. While health experts feel they may be able to develop immunotherapy to prevent the spread of the disease, they do not yet know how readily it does spread.
Publishing their findings in the February 19 issue of the online open-access journal mBio, researchers from the St. Gallan Cantonal Hospital in Switzerland, said the new strain (HCoV-EMC) is related to the pathogen that killed more than 750 people ten years earlier (2002/03), and has been found to penetrate cells that line the entry to the lungs and reach its peak ability to replicate in under 48 hours, compared to SARS, which takes up to four days.
The findings also show the virus is susceptible to treatment with interferons that have successfully treated other viral diseases, giving hope they can fight back against a large-scale outbreak.
So far, twelve cases have been confirmed this year, with eight from the Middle East and four in the UK, where three members of the same family were diagnosed last week. Because of this, researchers believe the disease is transmissible between humans.
However, the researchers, led by Volker Thiel, said just because the virus can get into respiratory cells so easily doesn´t mean it can easily get out again and spread to others.
“We don´t know whether the cases we observe are the tip of the iceberg, or whether many more people are infected without showing severe symptoms,” Thiel said in a statement.
One of the patients diagnosed in the UK last week died Sunday (Feb 17), said health officials at the Queen Elizabeth Hospital in Birmingham, where the patient was being treated. The officials, without revealing age or gender, said the patient was receiving treatment for another long-term health condition and had a compromised immune system.
Thiel and colleagues do not see the virus as being particularly contagious, given the limited number of cases seen since the virus was discovered in June of last year. However, it is still unsettling to know that the pathogen can adapt to the human body so easily and replicate much faster than SARS, they noted.
Coronaviruses typically cause upper respiratory diseases and the new strain has been shown to also cause severe kidney problems, breathing difficulties and fever.
Thiel said the new data indicate that HCoV-EMC made a recent jump from animals to humans--the human strain has been found very similar to one found in bats.
HCoV-EMC was first discovered last June when it was isolated from a man in Saudi Arabia who died from a severe respiratory infection and kidney failure. Since then, 11 more cases have been confirmed and a total of six deaths have occurred due to complications associated with the virus.
To get a clearer picture of the new coronavirus strain, Thiel and his team tested how well it could infect and multiply in the entryways to the human lung using cultured bronchial cells manipulated to mimic the airway lining. The lung´s lining (epithelium) is an important barrier against respiratory infections, but the team found it doesn´t do well in blocking HCoV-EMC, which easily and quickly replicates once it gains a foothold.
Thiel said his team also discovered that like SARS and the common cold, HCoV-EMC doesn´t provoke immune response. This is an indication the new strain is already well-adapted to the human host and that it uses the same strategy as other coronaviruses for evading non-specific immune mechanisms.
However, the team was able to boost immune response with lambda-type interferons, proteins that are released by host cells in response to infection and enable communication between cells to mount an immune response. Pre-treatment with interferons significantly reduced the number of infected cells. This finding is very encouraging, note the authors, since interferons have shown a good deal of promise in treating patients with SARS and Hepatitis C.
Thiel noted the work would not have been possible without efforts from several different sources from Switzerland, Germany, Denmark, and The Netherlands. He added further collaboration is crucial to continue the research in a positive direction. Future research into HCoV-EMC and other emerging diseases will require extensive cooperation among scientists and health agencies.
The future of this virus remains uncertain, but Thiel noted access to samples from a wider range of patients could help answer some fundamental questions, such as where the virus came from and what the true prevalence of the virus is.
Thiel´s research was funded by the Swiss National Science Foundation, the 3R Research Foundation Switzerland, the German Ministry of Education and Research, the German Research Foundation, the Danish Cancer Society and the Danish Council for Independent Research.