SARS Virus Search Was Scientific Sprint

On the heels of a presidential call to spend billions to fight the long-standing AIDS epidemic, scientists say there may be some lessons in the lightning speed at which researchers identified and mapped the SARS virus.

"Time is not on our side, so I ask Congress to move forward with the speed this crisis requires," President Bush said of HIV/AIDS Tuesday, calling for Congress to spend $15 billion to fund AIDS education programs and buy drugs to treat its victims.

Scientists have not found vaccines for either HIV/AIDS or SARS, but the pace of research on the virus behind severe acute respiratory syndrome was unprecedented.

Within just eight days, researchers identified the virus behind SARS, and in seven weeks they had zeroed in on its genetic structure. By contrast, it took scientists three years to identify the human immunodeficiency virus, the pathogen behind AIDS, and nearly two more years to map its genome.

How did they do it? Scientists say it was a combination of advanced technology, vital collaboration and a little luck.

"It was really quite a lucky break," said Michael Lai, a professor at the University of Southern California in Los Angeles, who specializes in coronaviruses — the class of viruses that includes the SARS pathogen, as well as about 200 of the known pathogens behind the common cold.

Easy Testing

SARS cases now appear to be declining, although the disease still poses a formidable threat. To date, more than 5,300 people have been infected with the virus in more than 20 countries and at least 355 have died from it.

Gaze at a coronavirus under a microscope and its name starts to make sense. The virus appears as an irregular sphere, topped by a "crown" — or in Latin, corona — of spikes, which are actually proteins.

Lai points out all other known viruses belonging to the coronavirus family have not grown in cell cultures. Instead, they require organ cultures to develop. Organ cultures must mimic the internal environment of an organ and are complicated to set up.

Getting a pathogen to grow in a cell culture is much easier and a much more common technique used by researchers in laboratories around the world — including those at the Centers for Disease Control in Atlanta and at Canada's National Microbiology Laboratory in Winnipeg, Manitoba, where researchers first managed to grow the SARS coronavirus from tissue samples taken from patients.

Four days after that breakthrough, Dutch scientists were able to conclusively show monkeys infected with the virus developed the disease. This was also unusual, Lai says, since coronaviruses don't normally develop in monkey cells.

"It was serendipity that the virus grew very well in these laboratory settings," said Sam Katz, a professor of infectious diseases at Duke University School of Medicine in Durham, N.C.

Katz points out HIV was notoriously difficult to grow in culture.

Good fortune aside, scientists say it's unlikely anyone would have been able to identify the SARS virus so quickly, if not for a deft collaboration effort led by the World Health Organization.

Working Together

U.S. health officials had begun to watch the SARS outbreak in China by February, noting the fast rate at which the disease appeared to infect health workers. And while the SARS death rate of 4.9 percent may seem low compared with other diseases, including influenza, it is still higher than previous killer diseases, including a 1918 flu epidemic that killed 25 million to 40 million people worldwide.

These factors, plus the indication that SARS was beginning to jump continents by sickening air travelers, prompted WHO on March 15 to issue a travel alert and declare SARS to be a "worldwide health threat."

Two days later, top epidemiologists from 11 laboratories in nine countries agreed to put aside rivalries and share data on the disease.

"Collaboration was critical," said Katz.

He points out that scientific work in understanding the AIDS virus was often more competitive than collaborative, which may have stalled results in understanding that disease.

"The race to find HIV was more like who would win the race to identify the virus that is causing this horrendous disease," he said.

Speedy Sequencing

By April 12 — less than a month after WHO issued its alert — Canadian scientists at the Michael Smith Genome Sciences Center in Vancouver, British Columbia, used a high-tech sequencing machine to map the virus's complete genome. These sequencing machines have been refined in recent years mostly to support the effort to map the human genome.

"The genetic mapping is very significant," Michael Ryan, a contagious disease specialist at WHO, told ABCNEWS' Nightline. "It allows us to understand the virus better."

The fact that SARS symptoms appear fairly quickly — much more quickly than, for example, symptoms appear in those infected with HIV — also helped researchers zero in on the disease.

And Donald Burke, an infectious disease expert at Johns Hopkins Bloomberg School of Public Health, told World News Tonight the upcoming summer months may help temper the spread of the virus as people spend less time in cramped, indoor quarters. This could allow more time for researchers to eradicate it, he said.

But before scientists can hope to find effective treatments for the disease and eliminate it, major questions need to be resolved. Centers for Disease Control Director Julie Gerberding says it will be weeks before reliable diagnostic SARS tests will be available and a vaccine, she says, is at least a year away.

Hurdles Ahead

Testing for the SARS virus — an important step in treating those with the disease — remains inconsistent. In preliminary tests, Canada's main virology laboratory has found only 40 percent of suspected SARS patients whose samples were examined there tested positive for the disease.

"Even though a number of groups are working very hard and quickly to get test kits that can be reliably used, I think we're still on the learning curve in perfecting these tests," said Brenda Hogue, a microbiologist and specialist in coronaviruses at Arizona State University in Tempe.

There is an added risk that, like the HIV retrovirus, the SARS virus may mutate over time and become more difficult to detect and attack. The disease could also be more complicated than researchers realize. Frank Plummer, scientific director of Canada's main virology laboratory, has expressed concern that more than one virus may be at play in causing SARS' symptoms.

One way to better understand the disease is to understand its origins. The SARS coronavirus, which is composed of a single strand of genetic units called RNA. The SARS strain has an unusually long genetic strand of RNA, which some believe makes it more vulnerable to mutation.

Since the virus had never been identified before, some have suggested the virus is a mutated version of a pathogen that lived in another animal. Early research suggests an avian version of the virus and a cow version may have combined and then infected a person. But researchers have yet to find that link.

By analyzing the SARS virus' genetic code and comparing it with similar viruses found in birds, pigs, cattle and other animals, researchers could learn which kinds of vaccines already used to treat animals might work in people against SARS.

This kind of genetic sleuthing could even lead to a medical bonus.

About 30 percent of cases of the common cold are caused by an agent similar to the SARS virus. By analyzing SARS' infection process and looking for ways to stop it, there is a chance — albeit slight — that researchers could stumble across a new antiviral agent that could stop the sniffles linked to the common cold.

Hogue said such a find is possible, but added, "It may be overly optimistic."