There is still no cure for HIV. No matter how hard doctors and researchers try, getting every last bit of viral DNA out of a person's system seems impossible. Small fragments of HIV's genetic code can tuck away in the cells of our immune system, waiting for the chance to start replicating again.
But if we were able to find these fragments, perhaps we could destroy them. Researchers in Australia may have developed a tool that will help scientists and doctors do just that.
"HIV is really very clever. Essentially, it is hiding in the exact same cells within the immune system that are meant to attack it," stated Sarah Palmer, a virologist at the University of Sydney in a press release. Palmer and her colleagues published their technique to detect even the sneakiest HIV DNA, in Cell Reports on Tuesday.
The technique, which is called full-length individual proviral sequencing, or FLIPS, builds on other methods to detect HIV DNA. Other tools must start at multiple places within the HIV DNA to sequence it and carry a risk of under- or over-estimating the virus's ability to replicate.
Because so-called "latent reservoirs" of HIV exist, it's been impossible to completely eradicate the disease from a person's body. Some people have gotten pretty close with a bone marrow transplant: Timothy Ray Brown, known as the Berlin patient, is often called the first person ever to be cured of HIV. He received a bone marrow transplant from a donor with a specific mutation that made his cells impenetrable to HIV.
But when talking about HIV, "cure" can mean two different things: completely eliminating all of the viral genetic information from a person's body, or just having absolutely no detectable traces of it. Brown is cured in the second sense, which is also known as a "functional" cure. He no longer takes daily medications.
Current antiretroviral medications to treat HIV only work by preventing the virus from producing new copies of itself. In the eyes of the Centers for Disease Control, that means the virus is no longer transmissible. But if the HIV virus isn't replicating, it can fly under the radar.
In order to attack the latent reservoirs, you'd have to be able to find them. Ideally, you'd just find the copies of the viral DNA that are actually dangerous—the ones that are capable of reproducing. That's only about 5 percent of the DNA found in these reservoirs, Palmer and her colleagues noted in their paper. Using their FLIPS technique, the researchers found that the majority of that 5 percent can be found in one particular kind of immune system cell, known as an effector memory T-cell. These cells have slightly different functions and slightly different patterns of proteins on their surface and move beyond our body's lymph nodes.
Figuring out how to use this new genetic tool to develop new treatments—or even a cure—would be the next step for scientists.
"Now that we've identified where the replication-competent virus is hiding, we can start work toward targeting these cells with new therapies aimed at fully eliminating HIV from the body," Palmer stated.
Uncommon Knowledge
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Kate Sheridan is a science writer. She's previously written for STAT, Hakai Magazine, the Montreal Gazette, and other digital and ... Read more
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