CRISPR, a breakthrough gene editing tool that is considered to be a promising method for removing HIV genome from infected cells, has proven to be a double-edged sword.

While the gene alteration allows the virus to be killed off in some cases, the resulting scar tissue can also cause the infection to become stronger.

For years, scientists have been trying to come up with ways to kill HIV. Several cures have been developed, such as the use of antiretroviral drugs, but the virus has evaded treatment by hiding its DNA in other parts of the patient's body and reemerging as soon as use of the medication is stopped.

To root out HIV infection, researchers turn to gene editing techniques, such as CRISPR, to cut out the genome of the virus and separate it from other cells. This is to allow the natural regenerative properties of the human body to patch up the broken genetic sequence and prevent the virus from establishing itself again.

However, in a study featured in the journal Cell Reports, scientists from the McGill University AIDS Center in Canada discovered drawbacks in using CRISPR to treat HIV. Instead of allowing the virus to be removed from affected cells, the process can also serve to strengthen the infection by causing it to replicate at a much faster rate.

The regenerated DNA also becomes different from what it was before, which prevents the cutting system from recognizing and attacking the viral infection once again. This allows HIV to become even more resistant to CRISPR.

"On the one hand, CRISPR inhibits HIV, but on the other, it helps the virus to escape and survive," lead investigator Chen Liang said.

"The surprise is that the resistance mutations are not the products of error-prone viral DNA copying, but rather are created by the cell's own repair machinery."

Despite this setback, Liang and colleagues believe — now that they have a better understanding of how HIV is able to elude antiretroviral drugs — they can focus their efforts in developing better ways to prevent it from happening during treatment.

The researchers are looking at using CRISPR to target HIV at different sites of its DNA to make it more difficult for the infection to develop resistance.

This "carpet-bombing" technique is supported by scientists at Temple University in Pennsylvania, who have conducted their own investigation on the efficacy of CRISPR in neutralizing the HIV infection in cells.

Kamel Khalili, lead author of the Temple University study, pointed out that the key to eliminating HIV could lie in attacking the virus at different sites using CRISPR, which could lessen the chance for the infection to escape initial treatment and become resistant later on.

Photo: Stew Dean | Flickr 

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