Scientists develop new ‘weapon’ in HIV fight

New treatment opens path to possible cure

By Amy Minsky, Canwest News ServiceJune 22, 2009

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Scientists have found a new way to fight — and possibly eradicate — HIV, according to a study released Sunday by a team of Canadian and American researchers.

“For 15 years we haven’t had a clue,” said Dr. Rafick-Pierre Sekaly. “But now, we do. Now there’s a whole new perspective of how to get rid of HIV,” said the Universite de Montreal professor and director of the Vaccine and Gene Therapy Institute of Florida.

The new “weapon” will combine antiretroviral therapy, the current treatment for HIV/AIDS, with a new one the researchers are calling an intelligent targeted chemotherapy.

When doctors started using antiretrovirals to block the virus in the mid-’90s, they were able to transform a patient with HIV from someone who was going to die within the next five years to someone who could live up to and more than 20 years with the infection, said Sekaly.

But the virus was only diminished, never eliminated; patients were condemned to take medication for the rest of their lives.

“The minute the patient stops taking the therapy the virus is reborn,” said Dr. Jean-Pierre Routy, associate professor of hematology at McGill University in Montreal.

“Then, the immune system is destroyed and the patient becomes sick again.”

Patients become reinfected because the HIV in their system feeds from a reservoir contained within a cell. The reservoir, Sekaly said, acts as a sanctuary for the virus.

For reasons unknown until now, these sanctuaries were unaffected by antiretroviral therapy.

The researchers discovered the virus inside the reservoir is unlike the typical HIV virus. Whereas viruses successfully controlled with antiretroviral therapy divide, the virus contained inside the reservoir is dormant. This renders it impermeable to therapies.

“So, if the cell lives, the virus lives,” said Sekaly. “But if you zap the reservoir with a chemo, there is no more virus to allow it to come back.”

Routy said a separate study — conducted in the United States and released in late May — confirmed that increasing the dose and potency of antiretroviral drugs doesn’t affect the level of virus hiding inside the reservoir.

Though there are limits to the success of antiretroviral therapy, Routy and Sekaly say the new treatment’s success will be contingent on a patient’s positive response to antiretroviral therapy.

If a patient shows success with current treatments, then the new treatment can target the cells, killing the remaining ones, and “the patient will remain virus-free for a long time or forever,” said Routy.

Some HIV-positive patients do not respond to antiretroviral therapy. For those patients, zapping the cell will not likely yield significant results.

However, Routy said antiretroviral therapy has successfully blocked the virus in 85 per cent of people in hospitals and large clinics in Canada, indicating they would be good candidates for the new treatment to eradicate HIV.

Article here.

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