Major scientific break through on HIV reveals how scientist have manage to shut down HIV replication permanently by edited HIV-1 DNA out of the genome of human immune cells, preventing virus replication and reinfection of the cleared cells.
Using the much-touted CRISPR/Cas9 gene editing method, scientists have demonstrated how they can edit HIV out of human immune cell DNA, and in doing so, can prevent the reinfection of unedited cells too.
The CRISPR/Cas9 gene-editing technique it’s set to revolutionise how we investigate and treat the root causes of genetic disease. It allows scientists to narrow in on a specific gene, and cut-and-paste parts of the DNA to change its function.
According Science Alert, the technique works by guiding ‘scissor-like’ proteins to targeted sections of DNA within a cell, and then prompting them to alter or ‘edit’ them in some way. CRISPR refers to a specific repeating sequence of DNA extracted from a prokaryote – a single-celled organism such as bacteria – which pairs up with an RNA-guided enzyme called Cas9.
So basically, if you want to edit the DNA of a virus within a human cell, you need a bacterium to go in, encounter the virus, and produce a strand of RNA that’s identical to the sequence of the virtual DNA.
This ‘guide RNA’ will then latch onto the Cas9 enzyme, and together they’ll search for the matching virus. Once they locate it, the Cas9 gets to cutting and destroying it.
Using this technique, researchers from Temple University managed to eliminate HIV-1 DNA from T cell genomes in human lab cultures, and when these cells were later exposed to the virus, they were protected from reinfection.
Lead researcher, Dr. Kamel Khalili, director of the Comprehensive NeuroAIDS Center at Temple University said while anti-retroviral drugs can help control HIV infection, once patients stop taking them, the virus starts replicating again from copies of its DNA in other cells.
“The findings are important on multiple level. 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.”
While gene-editing techniques have been tried before when it comes to HIV, this is the first time that scientists have figure out how to prevent further infections, which is crucial to the success of a treatment that offers better protection than our current anti-retroviral drugs. Not downplaying the benefits of the anti-retroviral drugs, once you stop taking them, the HIV starts overloading the T-cells again.
“Antiretroviral drugs are very good at controlling HIV infection. But patients on anti-retroviral therapy who stop taking the drugs suffer a rapid rebound in HIV replication.”
There’s still a lot more work to be done in getting this technique ready for something more advanced than human cells in a petri dish – particularly when it comes to perfect accuracy for the ‘cutting’ process – but it’s an exciting first step.