12 April 2016
The notoriously adaptive virus is able to survive even when attacked by gene-editing techniques
A team from the University of McGill, Montreal led by virologist, Chen Liang, have shown that not only is the virus able to defeat attempts to modify it through use of CRISPR gene-editing, the modification attempt may even contribute to its survival.
CRISPR makes use of the enzyme Cas9, a nuclease that specialises in ‘cutting’ DNA chains, effectively activating or deactivating specific genes. For their research, the team infected the T-cells that HIV targets with the enzyme, and using an RNA guide, targeted a specific site on the viruses DNA to prevent reproduction. Initial results were promising, with reproduction inhibited significantly. Prolonged analysis however, showed that the virus had only been delayed, and continued reproduction.
Although not a surprise - HIV has already proven itself capable of resisting many of the drugs used to treat it – Liang’s team attempted to identify the mutations that allowed the virus to escape destruction. They noticed that the mutations were found adjacent to the Cas9 target site, which suggests that the mutations which allowed the virus to survive were themselves the result of the attempted modification.
The paper, available here, suggests that their findings could have implications for use of the technique in fighting other viruses such as Herpes or Human Papillomavirus, which may also be able to develop mutations which are resistant to gene-editing.
Liang argues that whilst the result is worrying, it doesn’t mean an end to attempts to edit the HIV virus, but that a new methodology may be required.