Sars-like virus well adapted to infect humans, study finds

A new Sars-like virus that emerged in the Middle East last year and has killed six people is well adapted to infecting humans but could potentially be treated with drugs that boost the immune system, the first major study of the illness says.

The virus - novel coronavirus or NCoV - is from the same family as the common cold and severe acute respiratory syndrome. There have been 12 confirmed cases worldwide - including in Saudi Arabia, Jordan and Britain - and six patients have died, the latest yesterday in Britain.

In one of the first published studies about NCoV, which was unknown in humans until it was identified last September, researchers say it can penetrate the lining of passageways in the lungs and evade the immune system as easily as a cold virus. This shows it "grows very efficiently" in human cells and suggests it is well-equipped for infecting humans, said Volker Thiel of the Institute of Immunobiology at Kantonal Hospital in Switzerland, who led the study.

NCoV was identified when the World Health Organisation issued an international alert in September saying a completely new virus had infected a Qatari man in Britain who had recently been in Saudi Arabia.

Coronaviruses are a family of viruses that includes those that cause the common cold as well as the one that caused Sars - which emerged in China in 2002 and killed about 9.2 per cent of the 8,096 people it infected worldwide.

It infected 1,755 people in Hong Kong, killing 299.

Symptoms of both NCoV and Sars include severe respiratory illness, fever, coughing and breathing difficulties.

Scientists are not sure where the virus comes from, but say one possibility is it came from animals. Experts at Britain's Health Protection Agency say preliminary scientific analysis suggests its closest relatives are bat coronaviruses.

It is also unclear what the true prevalence of the virus is, since it is possible the 12 cases are just the most severe and more people may have contracted it with milder symptoms that have not been picked up.

Thiel says that although the virus may have jumped from animals to humans very recently, his research showed it is just as well adapted to infecting the human respiratory tract as other coronaviruses like Sars and the common cold viruses.

The study, published in mBio, an online journal of the American Society for Microbiology, also found that NCoV was susceptible to treatment with interferons, medicines that boost the immune system.

The medicines are also successfully used to treat other viral diseases like hepatitis C.

This opens up a possible mode of treatment in the event of a large-scale outbreak, the scientists say.

Thiel says that with the future of the virus uncertain, it is vital for laboratories and specialists around the world to co-operate swiftly to find out more about where it came from, how widespread it is and how infectious it might be.

"So far it looks like the virus is well contained, so in that sense I don't see any reason for increased fear," he says.

The World Health Organisation on Saturday urged countries to be vigilant over the spread of the new illness.

"Based on the current situation and available information, WHO encourages all member states to continue their surveillance for severe acute respiratory infections and to carefully review any unusual patterns," the United Nations health agency said.

Additional reporting by Agence France-Presse