When doctors started treating patients with HIV with a combination of antiretroviral drugs in the late 1990s, it quickly saved lives. But while the drugs can fend off AIDS and death, they aren't a cure for the infection; if someone stops taking the medicine, the virus springs back to life. And the drugs cause problems of their own, if they are available at all.
Researchers are working on an alternative: using a gene-editing technology to snip the HIV genome out of infected cells, getting rid of the virus.
"Antiretrovirals are not a cure," says Kamel Khalili, a researcher from Temple University and one of the authors of a study on the new approach. "The cure is that you completely eliminate the virus from the human body. There are only two ways to do that. Either identify the infected cells and kill the infected cells—or eliminate the virus from the infected cells, and save the cells. Save the cells, kill the virus. The approach we're using is the latter."
The researchers used CRISPR—a tool that can recognize a specific segment of DNA and then snip it out, like genetic scissors—on human cells taken from HIV-infected patients, and found that the method could fully eliminate the virus. The cell then stitches the loose ends of the genome back together using a natural repair mechanism.
In the study, they analyzed the entire genomes of the cells that they worked on to make sure there weren't any unintended effects. Everything worked normally. And not only did gene editing remove the infection, it also protected the cell from getting infected again.
"Once you excise the virus from the infected cell, as long as the gene-editing compound remains in the cell, that cell is protected against reinfection," says Khalili.
If the method makes it through the battery of studies needed to develop a drug, it might eventually be used to cure patients with HIV. The researchers are currently exploring various gene therapy strategies, like using nanoparticles or safe viruses to carry the CRISPR-Cas9 tool into cells.
Gene editing would have multiple advantages over antiretroviral treatment. The antiretroviral drugs are linked to multiple other problems, from heart disease to early Alzheimer's. "They age faster," says Khalili. "And the quality of life is very poor. On top of that, economically, it's very expensive. Then the person must continuously worry about whether or not the drug is working all the time, whether or not the virus is going to be reactivated, and so on."
Now that the researchers have shown that the method works in cell cultures, they're moving forward with animal studies. If those are successful, clinical trials will follow.
If it makes it through every step of the drug development process, it could be a cure for the 35 million people who are infected with HIV now. Two million more people get infected each year. This, however, is quite a long way off, and there are many hurdles to climb before then.