CRISPR’s latest trick is cutting HIV out of human cells

23 Mar 2016

Using CRISPR, this decade’s golden bullet for ‘fixing’ problems in human genetics using a medical cut and paste shortcut, scientists in the US claim to have eliminated HIV from human DNA.

Everything we’ve heard about CRISPR-Cas9 has been remarkable and revolutionary, but honing in on HIV and finding a (relatively) quick fix sounds utterly remarkable.

For those unfamiliar, at their core CRISPRs (clustered regularly interspaced short palindromic repeats) are DNA segments that contain repetitive sequences.

CRISPR-Cas9 is a technique that allows geneticists to search for, find and then zoom in on specific DNA sequences, slice out genes and edit them, before returning them into their original sequence.

Cheap and cheerful

Last July, the CRISPR-Cas9 technique got far more affordable, while researchers also worked out how to edit human T-cells, which play a key role in diseases like diabetes and cancer.

It is through this prism that the team from Temple University Health System found a way to fight back against HIV, which, as the virus that leads to AIDS, has been the cause of death for 25m people worldwide in about 35 years.

The presence of numerous copies of HIV in the human genome weakens the immune system and eventually causes AIDS, so slicing into the T-cell (where HIV-1 sits) and removing the unwanted elements could prove an incredible solution.

Testing their process on infected cells, the team led by Kamel Khalili claim that removing the HIV-1 DNA sequences results in the complete genome repairing itself and reuniting completely, with no side effects.

This paper reports that repairing infected CD4 T-cells eliminates the virus and strengthens against reinfection. It also shows that, when working ex vivo, treatment with the gene editing system can suppress viral replication and dramatically reduce viral load in patient cells.

Very important

“The findings are important on multiple levels,” says Dr. 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, they show that the system can protect cells from reinfection and that the technology is safe for the cells, with no toxic effects.”

Only a few weeks ago, the UK regulator that decides on the ethical nature of scientific experiments with regard to fertilisation gave the go-ahead for a scientist to create genetically-modified human embryos using CRISPR.

This all sounds like the precursor to pretty much any biological disaster movie, however there are strong pressures to deal with these worries head on.

For example, last summer, amid horror stories of the catastrophic damage caused by GMOs accidentally entering an environment where they could cause havoc, a new ‘kill switch’ was developed using CRISPR to prevent that happening.

If you’re still confused, here’s the wonderful Radiolab to explain what CRISPR is all about:

The Cas9 technique may soon be cast aside, with scientists in MIT recently claiming to have discovered an even better way to use CRISPR to genetically modify human genes, with Cpf1 the new kid on the block.

The Cas9 method uses RNA proteins to alter targeted sections of DNA in a cell. Cpf1 needs just one RNA molecule, and it’s far smaller than its predecessor, meaning it can be delivered into cells and tissues far more easily.

Main image of a blood vial via Shutterstock

Gordon Hunt was a journalist with Silicon Republic