The last few years has seen a massive leap in terms of genome editing. With the development of the incredible CRISPR/Cas9 technique, never before have scientists been able to so easily and precisely identify, edit, or remove specific sections of DNA. This has allowed scientists to target particular mutations, giving hope that the cure for certain inherited diseases could be around the corner. Now, researchers have used it to target HIV, and have managed to remove the genome of the virus from infected cells.
When HIV infects someone, its RNA is transcribed into HIV-1 DNA, which is then integrated into a specific immune system cell known as CD4+ T-cells. This means that the infected cells then replicate the HIV genome, producing more of the virus, which can then go on to infect more CD4+ T-cells. This has the effect of weakening the immune system, and eventually gives rise to acquired immune deficiency syndrome, or AIDS, with sufferers then succumbing to other normally beatable illnesses such as pneumonia.
Current antiretroviral drugs aim to stop the virus from infecting the cells in the first place, but once the virus has placed its DNA within the T-cells, there is little that can be done, and the infected cells then act in effect as a reservoir for HIV. “Antiretroviral drugs are very good at controlling HIV infection,” explains Kamel Khalili, senior investigator of the study published in Scientific Reports. “But patients on antiretroviral therapy who stop taking the drugs suffer a rapid rebound in HIV replication.”
So, the team from Temple University Health System instead decided to see if they could use the impressive precision of CRISPR to locate and remove the sections of HIV-derived DNA from infected T-cells. They showed that they were indeed able to remove the entire HIV genome without any other side effects on the host cells, which continued to grow and divide normally. Not only that, but the now HIV-eradicated T-cells were then immune to new infection by the virus later on.
“The findings are important on multiple levels,” says Dr. Khalili. “They demonstrate the effectiveness of our gene editing system in eliminating HIV from the DNA of CD4 T-cells and, by introducing mutations into the viral genome, permanently inactivating its replication. Further, they show that the system can protect cells from reinfection and that the technology is safe for the cells, with no toxic effects.”
Significantly, the researchers conducted the experiments using CD4 T-cells taken from HIV-infected patients and then grown in the lab, giving hope that the technique could be improved upon to such a degree that doctors will no longer simply stop the infection of cells, but cure them.