The swift fight against SARS


Disease: A small outbreak in China has renewed concerns, but researchers have made fast progress in understanding the deadly virus.

May 12, 2004|By Erika Niedowski | Erika Niedowski,SUN STAFF

It's been 14 months since the World Health Organization issued its unusual global health alert about a strange new respiratory illness in Southeast Asia that was spreading fast.

With no more warning than that, public health authorities launched an all-out offensive against the disease dubbed SARS. Scientists identified the virus behind it and sequenced its genome. Hospitals from Singapore to Canada tightened infection control measures to prevent transmission. People exposed to the virus were placed under quarantine or in isolation.

Four months later, after a stunning show of global cooperation and scientific skill, the World Health Organization declared victory: The world was SARS-free.

Now, another small outbreak in China - even though it appears to have been contained - has renewed concerns that severe acute respiratory syndrome could again become a public health threat of far-reaching proportions.

But researchers have made substantial progress toward understanding everything from how the virus replicates to which drugs may prove the most effective treatments.

"It's rather amazing, little over a year from the first case report, that we have very reliable diagnostic tests, that we've identified the virus, that we have vaccine prototypes and we have a handful of anti-viral drugs that are available for testing," says Dr. Gary J. Nabel, director of the National Institute of Allergy and Infectious Diseases' Vaccine Research Center in Bethesda.

2 promising vaccines

Last month, researchers at the institute announced the development of two promising vaccine candidates.

Based on distinctly different technologies, the two experimental vaccines use genetic material from the SARS virus to stimulate a protective immune response.

The first directs the body's cells to make proteins that mimic those on the surface of the virus. The second uses a separate virus - initially developed as a vaccine against smallpox - to shuttle DNA from the SARS virus into the body.

"We've learned how the virus is able to get into cells, and we've learned how to prevent it from getting into cells," says Dr. Bernard Moss, chief of the institute's Laboratory of Viral Diseases and senior author of a paper on the second vaccine published last month in the online Proceedings of the National Academy of Sciences. "So we have an outline for how to make a vaccine, and we can proceed along lines that are well-established for other vaccines."

The work, by all accounts, is preliminary; the virus with which researchers infected the mice didn't make them ill.

"It's encouraging," says Moss, "but more work has to be done to know whether it would be able to protect against SARS disease."

The pace of progress has been swift indeed. Whereas it took years for public health officials to identify the virus that causes AIDS, researchers in China are set to begin the first phase of a clinical trial on a SARS vaccine of their own.

Efforts to find drug treatments are also under way. Last spring, researchers with the U.S. Army Medical Research Institute of Infectious Diseases at Fort Detrick randomly screened about 200,000 compounds - including licensed drugs as well as those under development by pharmaceutical companies. About 50 compounds were found to inhibit the virus in tissue culture, says Jason Paragas, a microbiologist with the institute's virology division.

Of those, interferon alfacon-1, which is approved by the Food and Drug Administration as a hepatitis C treatment, has emerged as one of the more promising therapeutic candidates.

Researchers in Toronto - an epicenter of the SARS outbreak - described in The Journal of the American Medical Association in December the success of that drug in combination with steroids in treating a small number of SARS cases at North York General Hospital in Toronto.

In comparison with patients treated with steroids alone, those in the treatment group had normal chest X-rays sooner and needed supplemental oxygen for a shorter period of time.

"The speed and the quality of research that's come out is really stellar," Paragas says. "There have been so many major successes in under a year, it's really remarkable."

Some of the weapons being used to fight SARS, of course, have nothing to do with high-tech science: Iso- lating patients who have been exposed to the virus is a critical part of stopping its spread.

Hundreds of people were quarantined in Beijing and Anhui province last month after Chinese health officials reported a handful of suspected or confirmed SARS cases, all of which have been tied to people who worked in a national research lab. One of the patients died.

Two other cases of lab-acquired SARS - one in Singapore and the other in Taiwan - have also been reported since July, when the World Health Organization declared the world free of the disease. Those patients recovered, and neither was the source of a public outbreak. But the message, it seems, is clear.

`Clearly a warning sign'

"What that's saying to you is: This isn't something that can be taken casually," Nabel says. "Even relatively specialized personnel are becoming susceptible and getting infected. I think that's clearly a warning sign."

Dr. John G. Bartlett, chief of infectious diseases at the Johns Hopkins School of Medicine, credits the World Health Organization for its remarkably swift and coordinated response to last year's outbreak - which he says has left the world better prepared to deal with the next one, should it come.

"I think SARS was associated with this enormous number of stories that dealt with international collaboration, effective communication and heroism that are kind of unparalleled in modern medicine," he says. "I think you do learn a lot about how to deal with infectious diseases in a `mass-casualty' scenario."

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