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Scientists Still Chipping Away at SARS
By Kate Dalke

SARS may not make newspaper headlines these days, but the disease still makes news in scientific journals.

This week, researchers have confirmed, once again, but with more conclusive evidence, that SARS is caused by a novel coronavirus. Coronavirus is a family of viruses named for the crown-like shape of their surface proteins. They cause mild to severe respiratory illness, such as the common cold.

SARS virus used to infect monkeys (left) and morphologically identical particles isolated from monkeys after infection (right).

In the new study, the scientists revealed that the SARS-associated coronavirus was the overwhelming cause of infection in over 400 SARS patients from six countries.

“It’s really the only [study] that attempts to put together cohorts of patients from different countries with experimental data,” says Maria Zambon of the Health Protection Agency in London, who was a member of the research team.

The study was led by Thijs Kuiken of the Erasmus Medical Center in Rotterdam, the Netherlands, and included researchers from the United Kingdom, Germany, and Hong Kong.

There are six criteria for viral diseases, called Koch’s postulates, that scientists must fulfill before an organism can be confirmed as the cause of disease. Previous studies fulfilled three of these criteria, and this study fulfills the remaining three.

To fulfill the criteria, the researchers infected macaque monkeys with the SARS virus and replicated a similar disease to that found in humans. They analyzed the monkey tissue and compared it with SARS-infected human tissue. They also reisolated the virus from the monkeys.

Part of the SARS puzzle is the role of a separate respiratory virus, called human metapneumovirus, in the progression of disease. The scientists found the metapneumovirus in 12 percent of patients also infected with the SARS virus.

So far, there is no effective treatment for SARS—although results from a separate group of researchers in Germany are promising. In The Lancet this week, these researchers report using certain human immune system proteins, called interferons, to treat SARS-infected cells. Our bodies naturally produce interferons, but they can also be artificially synthesized.

In the study, the scientists used commercially produced interferons to block the virus from reproducing inside cells infected with SARS in the laboratory.

A specific interferon, known as interferon beta, could become the “drug of choice, alone or in combination with other antiviral drugs, for the treatment of SARS,” they say.

—Related Articles—

SARS Research Report

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Kuiken, T., et al. Newly discovered coronavirus as the primary cause of severe acute respiratory syndrome. The Lancet. Published online July 22, 2003.
Cinatl, J., et al. Treatment of SARS with human interferons. The Lancet 362, 293-294 (July 25, 2003).

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