23 February 2018

Can gene therapy be used to cure Aids?

Scientists are introducing altered DNA into patients to fight HIV, the virus that causes Aids.

HIV/Aids has been plaguing us for a long time and researchers are on a mission to find a cure.

A definite, traditional cure has not yet been established, but the latest developments in gene therapy to fight HIV may offer some hope.

Natural immunity

YourGenome defines gene therapy as "when DNA is introduced into a patient to treat a genetic disease. The new DNA usually contains a functioning gene to correct the effects of a disease-causing mutation."

These efforts are inspired by a man who was cured of HIV infection a decade ago by a cell transplant from a donor with natural immunity to the virus. He is the only person known to have been cured of HIV infection.

In all other cases, HIV cannot be eradicated and needs to be controlled by antiretroviral drugs. However, sometimes HIV infection cannot not be fully controlled by even the strongest drugs.

One step further

According to a New York Times article, gene therapy involves finding a way to create immunity by altering patients' own cells, thereby removing the need for antiretrovirals. To achieve this, they tried cutting the patient's DNA to disable the HIV entryway gene.

The initial gene editing experiments were disappointing because the altered T cells were outnumbered by T cells that were not altered. A good sign was however that patients in those studies had a big drop in the number of cells where HIV lurked in a dormant state (reservoir of silent disease).

Researchers are now hoping that keeping patients on strong antiviral medicines for at least a year will reduce this reservoir to a point where the body can control any residual disease by itself. 

University of Pennsylvania scientists are going a step further by adding a gene to help T cells recognise and kill HIV. This second part is called CAR-T therapy.

Great strides

The process of gene editing is showing great promise, as in the case of American Matt Chappell where it was a resounding success.(His HIV could not be fully controlled by the strongest Aids drugs.)

Scientists removed some of Chappell's blood cells, disabled a gene to help them resist HIV, and reintroduced these "edited" cells in 2014. Now his body controls HIV by itself – and researchers are trying to perfect the process that made this possible.

So far, it has given the San Francisco man the next best thing to a cure.

Image credit: iStock