Editing DNA: A New Way to Cure HIV?

It’s easy to confuse CRISPR with the latest hook-up app, but the only intimacy this DNA app is negotiating is between genes. Clustered regularly interspaced short palindromic repeat (aka CRISPR) is a bacteria’s immune system, which researchers have shown can be used like scissors to edit DNA in a living animal. Its possibilities may well be a boon in the efforts to find a cure for HIV.

A recent study, published last month in the journal Gene Therapy, reported using CRISPR for the first time to remove HIV DNA from live animals.

That sounds great, but what does it really mean? A quick interview with Dr. Chris Blazier, a researcher at Texas A&M University helped me understand.  According to Blazier, “The system was discovered by two French scientists, Jennifer Doudna and Emmanuelle Charpentier in 2012.”

[Editor’s note: It should be noted that creation and ownership of the CRISPR technology is currently under dispute (with Feng Zhang also claiming to have invented it).] 

“CRISPR,” Blazier says, “is part of the bacterial immune system that allows bacteria to remember viruses that have previously attacked them. It is interesting that a component of the bacterial immune system is being used against a human retrovirus.”

Kamel Khalili, director of the Comprehensive NeuroAIDS Center at Temple University,  led the team that successfully removed HIV DNA from live animals.

The scientists used CRISPR to target and remove the viral genes, sort of cut-and-pasting their way to healthy DNA. As Time magazine explains, “CRISPR’s power lies in the fact that it’s precise enough to find and cut out just the viral genes, leaving the animals’ own DNA intact.”

So far, removing HIV has only been done with transgenic animals, which are lab animals whose DNA has been modified by scientists.  (In this case, the lab rats had to be modified to get HIV, which they aren’t naturally susceptible to.) Human trials could still be far off, but as Dr. Keith R. Jerome, head of Vaccine and Infectious Diseases at the University of Washington noted in a press release, “This is an important study that marks the next step toward using HIV DNA excision from the host genome as part of a curative strategy.”

Blazier adds, “CRISPR has been used to genetically modify fungi, plants, and animals. We were able to modify the genomes of fungi, plants, and animals before CRISPR but not nearly as well. CRISPR is more precise and efficient than previous methods.”

Jerome acknowledged, “While this is an important and elegant advance, it’s important to remember that these were transgenic animals in which the HIV sequence was artificially introduced into every cell in the body. The next step may be more difficult — showing that this approach can work against an actual infection with HIV. It will be difficult because we know HIV is expert at finding hiding places within the body.”

Still, the potential of CRISPR to one-day edit HIV’s genetic material out of our own is remarkable.