Can an experimental drug
developed to treat epilepsy block the Aids virus? A preliminary lab study
suggests it's possible, and researchers are eager to try it in people.
with the drug after uncovering details of how they believe HIV cripples the
immune system to bring on Aids.
When tested in human
tissues in the laboratory, the drug "works beautifully" to prevent
HIV from destroying key cells of the immune system, said Dr Warner Greene of
the Gladstone Institutes in San Francisco. Those results appear in a paper by
Greene and others published online by the journal Nature.
In that work, and a
companion study published in Science, Greene and colleagues focus on how HIV
kills vital CD4 cells of the disease-fighting immune system.
CD4 cells infected
Researchers have long known
it infects some CD4 cells and turns them into virus-producing factories,
killing them in the process. But far more cells die without undergoing that
transformation. What is going on in these "bystander" CD4 cells?
The new work provides
evidence that HIV enters these cells but fails to produce a full-blown
infection, and in response the cells trigger a lethal attack on themselves by
the immune system.
It's "more of a
suicide than a murder," Greene said. "I believe this is the major
mechanism through which CD4 cells are depleted, which is the hallmark of Aids."
The epilepsy drug, which is
not on the market, blocks an enzyme that the research identified as playing a
key role in that immune system attack.
Prior studies of the drug
in people show it is safe, Greene said. So the researchers are talking to the drug
company about testing it in people infected with HIV. No timeline for such
studies has been set, he said.
Drug might be used on humans
Greene said if such studies
are successful, the drug might be used in people whose HIV resists standard
drugs. It might also be useful as a temporary treatment to keep HIV at bay for
people who can't immediately get standard drugs, he said. It's even possible,
he speculated, that the enzyme-blocking drug might help scientists eradicate
the virus from the body.
It's not clear yet whether
the enzyme-blocking approach will produce a practical therapy for HIV-infected
people, said Dr. Anthony Fauci, director of the National Institute of Allergy
and Infectious Diseases, who was not involved in the work.
But the new research behind
that strategy is "an important advance" toward understanding how HIV
kills immune system cells, he said.