AFRO-NETS> New Treatment May Flush Out Hidden AIDS Virus

["Dr. Leela McCullough" <leela@healthnet.org>]

New Treatment May Flush Out Hidden AIDS Virus
---------------------------------------------
Tuesday, September 16, 2003 02:34 PM ET
By Maggie Fox, Health and Science Correspondent
 
(Copied as fair use)
 
 
WASHINGTON (Reuters) - A two-step approach against AIDS involving 
first flushing the virus out of hiding then killing it with a 
toxic antibody may offer the first hope for controlling a life-
long AIDS infection, U.S. researchers reported on Tuesday.
 
The technique to locate and kill dormant HIV-infected immune sys-
tem cells works in mice and is ready to test in monkeys, the team 
at the University of California, Los Angeles, said.
 
It would not offer a cure, but might be a way to help people 
eventually stop taking the powerful drug cocktails that can keep 
the virus at bay, but which cause serious side-effects from diar-
rhea to heart disease.
 
"Our findings show potential for flushing HIV out of its hiding 
places in the body," Dr. Jerome Zack, an associate director of 
basic sciences for the UCLA AIDS Institute, said in a statement.
 
Highly active antiretroviral therapy, or HAART, can keep HIV pa-
tients healthy for decades, but they do not reach a latent virus 
-- which has been found to lurk inside immune system cells for 
decades and probably for a lifetime.
 
Writing in the September issue of the journal Immunity, Zack and 
colleagues said they had devised a two-step system for first par-
tially activating the cells the virus hides in, then killing the 
cells before the virus can escape.
 
The cells they targeted are called resting T-cells. T-cells are 
the immune system cells that HIV likes best to infect, and these 
cells can go dormant for long periods of time.
 
When they are dormant, HIV drugs cannot find them and work 
against the virus hiding inside.
 
"About one in a million T-cells holds latent HIV that the anti-
retroviral drugs can't touch," said Zack. "In order to make it 
visible, so you can attack it, you have to activate it," he added 
in a telephone interview.
 
Attempts to do so have failed in the past because activating all 
of a patient's T-cells can create potentially deadly illness.
 
TOXIN KILLS INFECTED CELLS
 
Zack's team used two compounds to only partially activate the T-
cells.
 
One, interleukin-7 or IL-7, is a naturally occurring compound. 
The other, called prostratin, comes from a tree native to the Pa-
cific island of Samoa.
 
"They hit a specific activation pathway but don't fully turn on 
cells," Zack said.
 
At that point they fire the "guided missile" -- an antibody, or 
targeting immune system compound, spliced to a piece of diphthe-
ria toxin.
 
"Because the antibody is linked to a toxin molecule, it pops into 
the cell," Zack said. "The toxin kills the cell before lots of 
viruses are made."
 
The approach worked in mice, clearing 70 percent to 80 percent of 
the reservoir of latent T-cells, Zack said. It did not mistakenly 
attack healthy cells -- an important finding.
 
But HIV is difficult to experiment with in animals because it is 
a virus that affects humans in a unique way. Zack said the next 
step is to try it in monkeys infected with an engineered human-
monkey virus called SHIV.
 
If tested in people, Zack envisions it would be used along with a 
HAART cocktail to keep HIV from spreading any further in the 
body.
 
Even then, he does not think it would offer a complete cure. HIV 
is believed to hide in other reservoirs, including certain brain 
cells. It can reactivate if HAART is stopped -- but patients may 
be able to safely stop HAART for years or even decades.
 
AIDS has killed 28 million people worldwide since the epidemic 
began in the 1980s, most of them in Africa, where drugs that can 
fight the disease are a rare luxury.
 
 
--
Dr. Leela McCullough
Director of Information Services
SATELLIFE
30 California Street, Watertown, MA 02472, USA
Tel: +1-617-926-9400
Fax: +1-617-926-1212
mailto:leela@usa.healthnet.org
http://www.healthnet.org

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