For the first time, researchers have modified HIV virus particles so that they can simultaneously, as it were, ‘cut and paste’ in our genome via biological processes.
Developed by biologists from the Aarhus University, the technology makes it possible to repair genomes in a new way. It also offers new perspectives for treating several viral infections:
“Now we can simultaneously cut out the part of the genome that is broken in sick cells, and patch the gap that arises in the genetic information which we have removed from the genome. The new aspect here is that we can bring the scissors and the patch together in the HIV particles in a fashion that no one else has done before,” says associate professor in genetics Jacob Giehm Mikkelsen from Aarhus University.
HIV has been known for being able to alter the human genome – as a matter of fact, this is the mechanism for every retrovirus out there – that’s just how they work. This mechanism is extremely interesting, and at a very basic level, it works like this: when a retrovirus enters a cell, its genetic information is in the form of RNA, which is different to DNA. The retrovirus uses a special enzyme to make a DNA copy of the RNA genome of the virus; this DNA copy travels to the nucleus of the cell, where it is spliced into the host’s genome, thus ordering it to create new virus particles.
What this research team has done is develop a technique that increases the safety of the cutting process, the so-called “gene editing”:
“In the past, the gene for the scissors has been transferred to the cells, which is dangerous because the cell keeps on producing scissors which can start cutting uncontrollably. But because we make the scissors in the form of a protein, they only cut for a few hours, after which they are broken down. And we ensure that the virus particle also brings along a small piece of genetic material to patch the hole,” says Jacob Giehm Mikkelsen.
According to them, there is no risk of further infection, and it has no negative effects:
“We call this a ‘hit-and-run’ technique because the process is fast and leaves no traces”.
This kind of treatment is called gene therapy – it has been proposed for quite a while, but so far, it has only been trialled with limited success – working around a person’s DNA is extremely dangerous, and cancer is always a potential result. However, if their results are as good as they claim, this might finally overcome that hurdle.
HIV infection is one of the areas where the researchers want to make use of the technique, and here the goal is to stop a specific gene from functioning – something that the protein scissors used here can do.
“By altering relevant cells in the immune system (T cells) we can make them resistant to HIV infection and perhaps even at the same time also equip them with genes that help fight HIV.
“So in this way HIV can in time become a tool in the fight against HIV,” says postdoc and PhD Yujia Cai of the research team.
Scientific Reference: Targeted genome editing by lentiviral protein transduction of zinc-finger and TAL-effector nucleases
