Unfortunately, mutations allow HIV to evade CRISPR gene-editing treatment

hiv vaccine therapy daily drugs color

Earlier this month, researchers published encouraging results that showed how gene editing could be used to target HIV and prevent it from attacking the body’s T cells. A second study examining the utilization of the CRISPR-Cas9 gene editing system, however, suggests this early optimism may be a bit premature. In this latter study, researchers found that some HIV particles were able to evade the gene editing of the CRISPR system, eventually infecting T cells.

The CRISPR-Cas9 system is a popular gene-editing tool that is being used by multiple research groups in the fight against HIV. In one strategy, the CRISPR-Cas9 system was able to recognize the HIV in infected T cells and was further able to splice it out of the infected cell. According to a study published last week in the journal Cell Reports, this method appears to be effective at first, but select HIV survived the treatment and begin to infect T cells two weeks later. In these survival cases, DNA sequencing shows that the virus developed mutations near the section of DNA that was targeted by the CRISPR/Cas 9 system.

Researchers posit that these changes are not the result of random mutations, but instead are a byproduct of the Cas9 treatment itself. According to this theory, the mutations are introduced when the gene editing system cuts the DNA, and the cell tries to self-repair the excision, creating areas of DNA called indels. Some of these indels leave the HIV intact, allowing it to infect other T cells. This form of evasion is not surprising given how HIV works, but the speed at which it occurred was shocking to researchers.

Researchers believe these results are a manageable setback for the CRISPR/Cas9 method and intend to continue refining the treatment. Some researchers want to expand the gene editing technique to target multiple critical HIV genes while others propose a dual method of treatment that combined CRISPR gene editing with traditional antiretroviral HIV drugs to provide a double punch that’ll knock out the virus. Other proposed techniques to prevent HIV infection target the human heart’s T cells, seeking to make them resistant to infection. A clinical trial is currently underway to test this latter human-focused strategy using an alternative gene editing tool known as zinc-finger nucleases.