August 29, 1997

On the cusp of a cure

Dr. David Ho

He's not ready to flash the "V" for victory yet but Dr. David Ho says it's an exciting time in the battle against AIDS.

The medical scientist and director of the Aaron Diamond AIDS Research Centre in New York City is familiar to most North Americans as TIME's 1996 "Man of the Year."

That recognition launched the soft-spoken researcher into an international group of statesmen, politicians and other high-profile people who have made a mark in the world.

And because of his work in AIDS research, Ho was the 21st annual W.C. Mackenzie Lecturer this summer.

On a hot July 24, University of Alberta students, faculty and staff crowded Bernard Snell Hall. Latecomers spilled over into the lobby looking for seats. They came to hear how Ho makes 99.99 per cent of the AIDS virus disappear in his clinical trial patients.

Ho was one of a small group of researchers who recognized from the beginning that AIDS was an infectious disease. Therefore, as with other infections, he reasoned, treatment should begin immediately.

"It's an active virus that churns away at enormous levels, levels that were previously under appreciated," says Ho. "Now, if you look at this situation from a new perspective, that HIV comes in and cranks away and eats up the critical immune cells on a daily basis, it now makes no sense to watch that process go on, as if you picked up cancer and decided not to treat it until a later stage."

Ten years ago, with only the drug AZT to work with, Ho says it made little difference whether doctors began treating AIDS patients early or late. He believes people undergoing a mono-therapy are basically doomed.

But now, with a combination of several powerful drugs, treatment starts as soon as the diagnosis is made, says Ho.

These therapeutic "cocktails" combine protease inhibitors with other anti-viral drugs. Given to AIDS patients in the early stages of the disease, these drug combinations immediately start attacking the human immuno-deficiency virus, preventing it from replicating to infect healthy cells.

The results are astonishing.

After five months, the viral load in his clinical patients was undetectable.

It's now been two years since the 20 AIDS patients began the aggressive, combination therapy and all are virtually virus free.

Free except for that unknown .01 per cent. While the virus is not detected in blood samples, researchers are checking spinal and seminal fluids, lymph nodes and tonsils.

Perhaps we'll never be able to eliminate the virus, says Ho. It may need to be treated as a lifelong condition, like diabetes.

The only way to test if patients are virus-free is to stop treatment. While no one has volunteered to be the first, Ho is designing the ethical model for the next stage of research, the evaluation.

Meanwhile, Dr. Lung-Ji Chang, a researcher in the U of A's department of medical microbiology and immunology, is collaborating with Ho on other AIDS projects.

Chang is testing a vaccine against AIDS. The vaccine will be evaluated in mice specially bred with the human immune system. Chang says he'll know within a year if the mice have protective immunity against AIDS.

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