Scientists
have removed HIV from human immune cells using a new gene-editing technique
They've
managed to shut down HIV replication permanently.
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.
If
you haven’t heard of the CRISPR/Cas9 gene-editing technique before,
get ready to hear a whole lot more about it in 2016, because 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.
CRISPR/Cas9
is what researchers in the UK have recently gotten approval to use
on human embryos so they can figure out how to improve IVF success rates and
reduce miscarriages, and it’s what Chinese scientists were caught using in 2015to 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 in the future.
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.
"The
findings are important on multiple levels," says lead researcher 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 figure out how to
prevent further infections, which is crucial to the success of a treatment that
offers better protection than our current antiretroviral 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 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.