• E-mail
• Print
• Comment
• Font Size
• Digg
• del.icio.us
• Discuss article

Discovery By Scientists Could Aid SARS Treatment Study Explains Virus's Deadly Effect on Lungs

Posted on: Friday, 15 July 2005, 12:00 CDT

Scientists may have solved the chemical riddle of why the SARS virus causes such a deadly pneumonia, and they have developed a simple therapy that promises to decrease the extraordinarily high death rate, according to a report this week in the journal Nature Medicine.

SARS, or sudden acute respiratory syndrome, spawned an epidemic of illness and fear in 2003, killing nearly 800 people worldwide and shutting down stores, airports, schools, factories and hotels across Asia, the epicenter of the outbreak, for fear that the disease would spread in crowds.

Researchers working with mice have discovered that SARS, caused by a previously unknown member of the coronavirus family, interferes with a crucial enzyme pathway that regulates the balance of body fluids. By blocking that enzyme system in the lungs, the virus allows liquid to leak into the air sacs, making them boggy and inefficient.

"Now we can really understand why SARS was such a killer, compared to other viruses that are relatively harmless," said Josef Penninger, a professor at the Institute of Molecular Biotechnology of the Austrian Academy of Science, the lead author of the new paper.

The research team included scientists from Europe and Asia who were working with mice.

Humans and mice have the same enzyme system, the renin- angiotensin pathway, which is crucial in both species for blood pressure and fluid regulation. If the findings can be matched in humans, the research may well lead to a new treatment for SARS and for many other diseases that cause death by allowing fluid into the lungs.

Researchers found that they could protect their SARS-infected mice from lung failure and death by giving them large amounts of angiotensin converting enzyme-2, the molecule whose function was blocked by the virus. By flooding the system with intravenous infusions of the protein, they could overwhelm the blockade and its deadly effects.

Scientists already know how to produce a synthetic version, making the move from lab animals to human therapy relatively straightforward.

"We are pretty confident that this is relevant to humans, and a treatment could be available in another two to three years," Penninger said.

Their discovery could have broader implications, because the type of lung damage caused by SARS also is caused by other deadly diseases. SARS victims die because their lungs fill with fluid. The SARS virus is only one cause of this acute respiratory distress syndrome, now untreatable, which causes up to a million deaths worldwide each year. The syndrome can also result from cancers, burns and infections, including bird flu, which many epidemiologists believe will be the next big disease outbreak in Asia.

"SARS may have put us on the trail of a new therapy that could be used for many diseases," Penninger said.

Last year, doctors studying the SARS virus were at first confused to find that the virus bound to a receptor in the renin-angiotensin system, a pathway not previously associated with the lungs. Later research found that receptors for the system existed in the lungs and the intestines.

But some scientists cautioned that it remained to be determined whether the mouse model was relevant to humans.

"Infection in mice does not produce the typical picture seen in human disease," said John Nicholls, a researcher at the University of Hong Kong, in a commentary accompanying the report.

But he said the research might be "particularly relevant as we prepare to confront a potential avian flu epidemic, armed with only a limited number of therapeutic options."

Source: International Herald Tribune

More News in this Category