The Gene Fix That Could Cure HIV

Antiretroviral drugs make HIV manageable, but gene therapies could eliminate the virus altogether — provided the treatments can be made safe and economical

A human T-cell (blue) under attack by HIV virus particles (yellow). Credit: Seth Pincus, Elizabeth Fischer and Austin Athman, National Institute of Allergy and Infectious Diseases, National Institutes of Health

In the mid-1990s, scientists made a curious but remarkable discovery: A man named Stephen Crohn seemed virtually immune to HIV.

In the years before that discovery, Crohn’s boyfriend and many of his friends had died of AIDS. But despite being sexually active with men infected with HIV, Crohn himself never got sick. The reason, researchers found, was that Crohn had a mutation in a gene called CCR5, which effectively blocks HIV from entering immune cells.

In the decades since, that genetic mutation — known as delta 32 — has been of particular interest to researchers studying HIV. It’s also the same mutation that the Chinese scientist He Jiankui tried to replicate when he shocked the scientific community last year by using CRISPR to edit the genes of human embryos. The twin girls who were later born were the first children whose DNA had been purposefully edited.

Now, a handful of research teams are trying to recreate the rare protective mutation in HIV patients in hopes of curing the virus. One biotech company, Maryland-based American Gene Technologies, plans to begin a clinical trial by the end of the year. Some scientists believe treatments that use genetic material — DNA or RNA — are the best hope for a one-time, long-term cure for HIV, which has killed more than 32 million people around the world. But these so-called gene therapies are not without major challenges.

So far, only two people appear to have been cured of HIV: Timothy Ray Brown, known as “the Berlin patient,” and more recently, an anonymous London patient. Both received bone marrow transplants to treat blood cancers, and in both cases, the donors harbored CCR5 mutations. In a bone marrow transplant, the recipient’s unhealthy blood stem cells are replaced with a donor’s healthy ones, which go on to make a variety of immune cells. In essence, the transplants reset the two men’s immune systems and eliminated HIV from their systems.

But it’s not practical to give all HIV patients bone marrow transplants. For one, it’s rare enough…