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.