Scientists using CRISPR gene-editing technology have removed HIV DNA from three different animals, including a “humanised” variant of mice that had human immune cells transplanted into them and had been infected with the virus.
In the study, published today in the journal Molecular Therapy, the team genetically inactivated HIV-1 in humanised transgenic mice. Scientists were able to reduce the RNA expression of viral genes by roughly 60 to 95%.
The team, which was made up of scientists from the Lewis Katz School of Medicine at Temple University (LKSOM) and the University of Pittsburgh, used an animal model where latent HIV-1 infection was housed in humanised mice implanted with human immune cells, including T cells the HIV-1 virus.
“These animals carry latent HIV in the genomes of human T cells, where the virus can escape detection,” said Wenhui Hu, associate professor in the Center for Metabolic Disease Research and the Department of Pathology.
However, following a single treatment with CRISPR viral fragments were successfully removed from the infected human cells embedded in mouse tissues and organs.
Scientists tested their system in mice acutely infected with EcoHIV, the mouse equivalent of human HIV-1.
In 96% of mice infected with EcoHIV excision using the CRISPR technique worked effectively, providing the first evidence for HIV-1 eradication by prophylactic treatment with a CRISPR/Cas9 system.
“During acute infection, HIV actively replicates,” said Kamel Khalili, 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 LKSOMDr.
“With EcoHIV mice, we were able to investigate the ability of the CRISPR strategy to block viral replication and potentially prevent systemic infection.”
The scientists’ work builds on a previous proof-of-concept study that the team published in 2016, in which they used transgenic rat and mouse models with HIV-1 DNA incorporated into the genome of every tissue of the animals’ bodies.
In that study they demonstrated that their strategy could delete the targeted fragments of HIV-1 from the genome in most tissues in the experimental animals.
“Our new study is more comprehensive,” said Hu. “We confirmed the data from our previous work and have improved the efficiency of our gene editing strategy. We also show that the strategy is effective in two additional mouse models, one representing acute infection in mouse cells and the other representing chronic, or latent, infection in human cells.”
From here, the scientists want to repeat their study first in primates before, eventually, testing CRISPR’s ability to remove HIV-1 DNA in human clinical trials.
“The next stage would be to repeat the study in primates, a more suitable animal model where HIV infection induces disease, in order to further demonstrate elimination of HIV-1 DNA in latently infected T cells and other sanctuary sites for HIV-1, including brain cells,” said Khalili.
“Our eventual goal is a clinical trial in human patients.”