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THURSDAY, April 1 (HealthDayNews) -- Patients with a rare but deadly form of leukemia linked to viral infection may now have reason for hope. Researchers are hot on the trail of medications that could stop the virus, called HTLV-1, from spreading throughout the bloodstream, according to a new study.

"It's certainly a few years in the future, but I think the results that we are reporting here are the first big steps in that direction," said lead researcher Suzanne Shuker, a professor of biochemistry at the Georgia Institute of Technology, in Atlanta.

The findings were to be reported Thursday at the annual meeting of the American Chemical Society in Anaheim, Calif.

The vast majority of leukemias, which originate in bone marrow, are caused by random mutations in genes, triggered by unknown causes. However, about 40 years ago, scientists discovered that a subset of leukemias affecting the blood's immune T-cells was strongly linked to infection with a virus called HTLV-1. They labeled the illness adult T-cell leukemia.

Experts estimate that about 15 million to 20 million people worldwide carry the HTLV-1 virus, which belongs to the same retrovirus group of infectious agents that includes HIV. Like HIV, HTLV-1 can be spread by sexual contact, intravenous drug use, or contaminated blood transfusions.

"The virus is endemic in four areas of the world," explained Dr. Marshall Lichtman, executive vice president for research and medical programs at the Leukemia and Lymphoma Society. "One is the islands of southern Japan, there's a certain area in the Caribbean islands, in Africa, and the southeastern United States."

Only about 3 percent of HTLV-1 carriers will go on to develop adult T-cell leukemia, which has no effective treatment or cure. Although precise records are unavailable, Lichtman estimates that a few hundred Americans now suffer from the disease.

In their study, Shuker and her team took advantage of research into drugs called protease inhibitors, which since the mid-1990s have been crucial in extending the lives of people infected with the AIDS-causing HIV.

Protease inhibitors prevent HIV from replicating because they block the activity of an enzyme called protease. In HTLV-1, as in HIV, "the protease is necessary for the virus to make the protein that it needs to be infectious," Shuker explained.

As proteins emerge from the virus, they are cut into smaller segments by protease, which acts like "a pair of scissors," Shuker said.

"We're trying to find something that will block the scissors," she added.

She and her team may already be succeeding. "We're reporting at this meeting on some inhibitors that we just tested last week, and some of them look pretty good," she said.

However, roadblocks remain, and the ultimate goal --- a drug that slows or reverses adult T-cell leukemia -- is still years away. Even after suitable drug candidates are found, "there's the whole [FDA] approvals process," Shuker pointed out.

Lichtman agreed, describing the research as "in an extremely early stage."

Still, Shuker believes HTLV-1 is "a very important virus to learn about, since there are no treatments and since it can be spread in similar ways to HIV."

And there's a small chance the virus could someday become even more dangerous.

"If the virus were to mutate and become more virulent, it could be a real problem," Shuker said. "So it's certainly important at this stage to try and develop treatments, before there's a larger outbreak, as we've seen with HIV."

More information

To learn more about adult T-cell leukemia and other leukemias, visit the National Cancer Institute and the American Cancer Society.

(SOURCES: Suzanne Shuker, Ph.D, assistant professor, chemistry, Georgia Institute of Technology, Atlanta; Marshall Lichtman, M.D., professor, University of Rochester Medical Center, Rochester, N.Y., and executive vice president for research and medical programs, Leukemia and Lymphoma Society, White Plains, N.Y.; April 1, 2004, presentation, American Chemical Society annual meeting, Anaheim, Calif.)

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