Researchers have, for the first time, successfully excised a segment of HIV-1 DNA from the genomes of living animals and published their findings in the journal Gene Therapy.
“In a proof-of-concept study, we show that our gene editing technology can be effectively delivered to many organs of two small animal models and excise large fragments of viral DNA from the host cell genome,” lead investigator on the study, Kamel Khalili, PhD, Laura H. Carnell Professor and Chair of the Department of Neuroscience, Director of the Center for Neurovirology, and Director of the Comprehensive NeuroAIDS Center at the Lewis Katz School of Medicine at Temple University (LKSOM) said in a prepared statement about the study.
In earlier research, Dr. Khalili and colleagues were able to show that their novel gene editing system, which is based on CRISPR/Cas9 technology, has the ability to eliminate HIV-1 from infected cells in vitro with no adverse effect on the host cells. In ex vivo experiments using clinical specimens, including T-cells from patients infected with HIV that were expanded in culture, they showed that viral replication was significantly reduced following treatment with the gene editing system.
The latest study was designed specifically to test whether the gene editing technology could also eliminate HIV-1 in transgenic rats and mice, in which HIV DNA is incorporated into the genome of every cell and organ of the experimental animals. In order to deliver the technology to cells in living animals, Dr. Khalili and colleagues employed a recombinant adeno-associated viral (rAAV) vector delivery system. They also engineered the gene editing apparatus to cleave the integrated HIV-1 DNA in the host cell genome, leading to excision of the viral DNA fragment from the host genome.
Two weeks after delivery of the rAAV CRISPR/Cas-9 molecules into the bloodstream, the researchers analyzed the DNA of tissues collected from the animals. The results showed that the targeted segment of HIV-1 DNA had been excised from the viral genome in every tissue, including the brain, heart, kidney, liver, lungs, spleen, and blood cells. Analyses of viral RNA in the rat model showed that the strategy significantly reduced levels of HIV-1 RNA in circulating lymphocytes, as well as in lymph nodes, indicating that viral genome excision had significantly impacted HIV-1 gene expression in cells carrying integrated viral DNA.
The research was supported in part by grants provided by the National Institutes of Health (P30MH092177 and R01NS087971).