Building on earlier research that removed HIV from cultured cells (see BioNews 764), the researchers successfully treated infected cells from AIDS patients, and they hope that the technique could be developed into a treatment for the disease.
The HIV retrovirus inserts itself permanently into the genome of infected cells and, while anti-retroviral therapy (ART) is able to control HIV infection, it can only lower the viral load, not eliminate it. Copies of HIV can persist in other tissues and, if ART is stopped, the infection can reassert itself.
'Therefore, most HIV-1-infected individuals, even those who respond very well to ART must maintain lifelong ART due to persistence of HIV-1-infected reservoir cells,' said Professor Kamel Khalili, director of the Center for Neurovirology at Temple University in Philadelphia and lead author of the study, which was published in Scientific Reports.
Professor Khalili's team had previously used the CRISPR/Cas9 genome-editing technique to 'cut out' HIV from various immune cells in culture. In this study they performed the same technique on infected CD4+ T cells taken from the blood HIV-positive patients.
They were able to not only eliminate the virus but also protect the cell from reinfection with HIV because the CRISPR machinery was left inside the cell. Importantly, the team did not detect any off-target effects, meaning that only the HIV was edited out and no other parts of the genome were inadvertently modified. The cleared cells appeared to grow and function normally.
'The findings are important on multiple levels,' said Professor 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 inactivate viral 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.'
Professor Khalili told Voice of America that human clinical trials could get underway in two to three years.