Gene Editing Could Make Anyone Immune to AIDS
By Aaron Rowe
Some people have a mutation that makes them amazingly resistant to HIV — and now, scientists may have found a way to give that immunity to anyone.
Here’s a hint: “amazingly resistant” does not equal “immune”.
Viruses enter cells and take them over, but to get inside, they need a handhold. HIV pulls itself in by grabbing onto a protein called CCR5, which decorates the surface of T-cells, which are one of the two major types of white blood cells and play an important role in helping the body fight infections. Back in the 1990’s, researchers took interest in a handful of promiscuous gay men who were able to engage in sexual relations with their HIV-positive partners with impunity. Most of them had a mutation that kept their cells from producing normal CCR5 protein.
Armed with that knowledge, scientists have developed several tactics to block the production of CCR5 or perturb its shape so that the HIV virus can’t grab onto it during the first step of its hijacking attempt. The strategy is much akin to cutting your hair before a wrestling match: It gives your opponent one less thing to grab onto.
Actually, it’s more akin to “bricking up all the doors and windows in your house to keep out burglars.” Which is to say that while it may work, it may also have interesting / unplanned / unwanted side effects. Because CCR5 is there for some purpose, and the odds are high that the mutation (negatively) affects that purpose, too.
In the latest version of this defense, Carl June and his colleagues at the University of Pennsylvania used a highly engineered protein, called a zinc finger nuclease, to clip the CCR5 gene out of some T-cells. Left without the recipe for that protein, the cells are nearly impenetrable. His report appeared on the Nature Biotechnology website yesterday.
June tested the procedure on cultured T-cells and mice — not humans — so it should be a source of guarded optimism, because it’s not certain the technique would work in humans. In theory, AIDS doctors could take some T-cells out of an infected person, edit their genomes, and stick them back into their patient. Once they have returned to the body, each resistant cell will thrive and multiply in spite of the disease. This trick would not eliminate the virus, but it might be able to permanently raise the T-cell counts of AIDS patients, increasing their ability to resist secondary infections and remain healthy.
You body makes billions of T-cells a week. So unless you’re doing this to patients on a regular basis, or you gene engineer their hematopoietic stem cells so that all new T-cells come out so modified, this isn’t going to do much good.
I’s going to be interesting to see how long it takes before we’ll get some researchers with the balls to do it the right way (gene engineering HSCs), and even more interesting to see how the anti-biotech nuts will react to the proposed studies.