Interferon helps infected monkeys breathe more easily.
23 February 2004

HELEN R. PILCHER

Interferon is already avaiable and safe to use on humans. © SPL

A drug used to treat hepatitis C may prove useful against severe acute respiratory syndrome (SARS). The drug, called interferon-alpha, eases symptoms in infected monkeys, and may make them less infectious too.

Interferon-alpha, an antiviral used to treat a broad spectrum of viruses, had previously shown promise against SARS in cell culture tests. Albert Osterhaus and his colleagues are the first to show that it also works in animals¹.

The drug is already commercially available and has no serious side effects. The next step is to test it against SARS if another outbreak occurs, says Osterhaus, who works at the Erasmus Medical Centre, Rotterdam, the Netherlands.

The team gave macaques three doses of interferon-alpha, and then infected them with SARS. Two days later, the monkeys' throats were almost free of viral particles, meaning they exhaled fewer infectious particles. "If the same thing is seen in human patients, maybe the virus will spread less," says Osterhaus. Untreated animals' throats teemed with virus.

Treated monkeys also had 10,000 times fewer infectious viral particles in their lungs than non-treated animals. This hints that the drug is slowing virus replication. And macaques on interferon had fewer fluid-filled cells in their lungs' lining, allowing them to breathe more easily.

When interferon-alpha was given after infection with the virus, the effects were similar but less pronounced.

High risk

There are currently no effective treatments or vaccines for SARS. Vaccines are in development, but they may be a long way off says virologist Stuart Siddell from Bristol University, UK. "Drugs like this could be the best way to deal with the problem," he says.

SARS has killed over 800 people and infected more than 8,000 since it emerged two years ago. By spring 2003, the World Health Organization had labelled the disease a worldwide threat. Careful quarantining brought the problem under control by the end of that summer. But earlier this year, a handful of new cases popped up in China.

At present the disease doesn't seem to be spreading, but some fear that it's only a matter of time before another epidemic strikes.

Interferon-alpha could be given as a prophylactic to healthcare workers and the friends and families of SARS patients, says virologist John Oxford from the London Queen Mary's School of Medicine. "The treatment could be used to protect those most at risk," he says. It may also prove useful as treatment for those with the disease.

1. Haagmans, B. L. et al. Pegylated interferon-a protects type 1 pneumocytes against SARS coronavirus infection in macaques. Nature Medicine, published online, doi:10.1038/nm1001 (2004).