Retroviruses like HIV-1 can integrate themselves into the host genome, taking up residence there, and can be reactivated to cause infection even after treatment. By cutting the virus out of the host genome, researchers from Temple University and elsewhere hope to find a way to prevent such reactivations.
As they report in the Proceedings of the National Academy of Sciences this week, researchers led by Temple's Kamel Khalili used genome editing to slice the HIV-1 virus out of cells with latent infections.
Using gRNA, Khalili and his team targeted the CRISPR/Cas-9 system to the LTR U3 region of HIV-1 to remove a 9,709-base pair fragment of integrated proviral DNA from myeloid cells. They further note that the presence of the gRNA in Cas-9-expressing cells seemed to prevent subsequent infections. This, they write, "suggests that Cas9/gRNA can be engineered to provide a specific, efficacious prophylactic and therapeutic approach against AIDS."
"We were extremely happy with the outcome," Khalili tells The Scientist. "It was a little bit … mind-boggling how this system really can identify a single copy of the virus in a chromosome, which is highly packed DNA, and exactly cleave that region."
The Scientist notes that delivery is still a challenge for CRISPR-based approaches, as are the possibility of off-target effects, though Khalili's group couldn't detect any.
It adds that Khalili plans to next test this approach in mice.