HIV-1 genomes were eliminated from human T-lymphoid cells by CRISPR/Cas9 gene editing technique by scientists demonstrating how they can edit HIV out of human immune cell DNA, and in doing so also prevent the reinfection of unedited cells.
Get ready to hear a whole lot more about CRISPR/Cas9 gene-editing technique in 2016 because it’s set to revolutionize how we investigate and treat the causes of disease. It allows scientists to narrow in on a specific gene, and cut-and-paste parts of the DNA to change its function.
In the UK researchers have recently gotten approval to use CRISPR/Cas9 on human embryos so they can figure out how to improve IVF success rates and reduce miscarriages, and Chinese scientists were caught using it in 2015 to tweak human embryos on the down-low. Earlier this year, scientists started using CRISPR/Cas9 to successfully treat a genetic disease – Duchenne muscular dystrophy – in living mammals for the first time, and now it’s showing real potential as a possible treatment for HIV.
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 DNA-editing enzyme called Cas9. So basically, if you want to edit the DNA of a virus within a human cell, you need a ‘guide RNA’ that is complementary to the virus DNA and CRISPR complex to go in the target cell. This ‘guide RNA’ will then latch onto the Cas9 enzyme, and together they’ll search for the matching virus DNA. Once they locate it, the Cas9 starts cutting and destroying it.
Using this technique, researchers from Temple University eliminated 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.
“The findings are important on multiple levels,” says lead researcher Dr. Kamel 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,” he adds, “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 trialled before when it comes to HIV, this is the first time that scientists have figured 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. Once you stop taking these drugs, the HIV starts overloading the T-cells again.
“Antiretroviral drugs are very good at controlling HIV infection,” says Khalili. “But patients on antiretroviral 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 the HIV removal from human immune cells using a new gene-editing technique ready to use on us, as humans are more advanced than our cells in a petri dish – particularly when it comes to perfect accuracy for the ‘cutting’ process – but it’s an exciting step forward.