About 15 years ago, pharmaceutical researchers discovered the first
anti-retroviral drugs - medicines that can successfully combat HIV, the
virus that causes AIDS. As time has gone on, these drugs have been
made more potent, and patients who take them live longer.
In
HIV treatment, one problem has persisted, says Jean Pierre Routy, an
HIV researcher at McGill University in Montreal. Scientists haven't
been able to actually eliminate the virus from the bodies of infected
patients. But Routy believes his research could show a way this might
be accomplished in the future.
Routy says anti-retrovirals do a
good job at killing viruses that are circulating freely in the
bloodstream. After taking them for a few months, HIV patients have
virus levels that are almost undetectable. But if a patient stops
taking the drugs, the virus rebounds. That's because even the most
potent HIV drug cannot kill all of the viruses in a patient's body.
And there's new thinking on why this is so. Routy suggests that the
viruses go dormant.
"If the virus persists, it's because it is
sleeping in immune cells, in special immune cells called memory, or
CD4, cells that keep the memory of the immune system," he says.
Using
a sophisticated blood filtering machine, Routy was able to show that
HIV was hiding in a very small number of CD4 cells in some patients who
were taking antiretroviral drugs.
"We took from a large
quantity of cells from each patient in a study and then we had enough
cells to select the cells, to do cell sorting, to study… in fact five
subgroups of CD4 cells," Routy says. "And we found where the virus
hides in each subset. That was never done before."
Routy
explains that once the HIV gets inside these immune system CD4 cells,
it's almost impossible for antiretroviral drugs to target the virus and
kill it. He says instead, doctors need to give patients drugs that can
target these cells. Such drugs exist. They're a new generation of
medicines being used to fight cancer, and they can attack so-called
sleeping immune cells that harbor the virus.
"So the idea is
to add on new therapy to wake [the CD4 cells] up," he says. "[They]
die, and [they] will be replaced, and then we can expect to decrease
the HIV reservoir, or one day, in one or two decades, to cure, to
eliminate all of the infected cells."
If these infected cells
can be killed, Routy believes HIV can then be eliminated from a
patient's body. He says he will continue to work on this line of
investigation.
Routy's research is published in the journal Nature Medicine.
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