Gene therapy, an approach most commonly explored for curing chronic genetic diseases such as cystic fibrosis, may also prove practical for disease prevention. In research published today inNature1, scientists in California show that a single injection — which inserted the DNA for an HIV-neutralizing antibody into the muscle cells of live mice — completely protected the animals against HIV transmission.
The road to a vaccine against HIV has proved to be far longer than originally anticipated. More than 2 million adults are newly infected with HIV every year and, nearly three decades after the virus was first identified, researchers haven’t found a reliable way to prevent infection. The classic vaccine approach, which uses all or part of an inactivated virus to induce immunity, has yielded little success because HIV has managed to disguise most of the easily-recognised external structures that antibodies would target. Researchers have thus had a tough time finding a molecule that can induce even moderately broad responses against the virus in all its different mutations. So although it might sound extreme to use gene therapy as a preventative treatment for HIV/AIDS, the method could provide a much-needed alternative.
David Baltimore, a virologist and HIV researcher at the California Institute of Technology in Pasadena, and his colleagues used a genetically altered adenovirus to infect muscle cells and deliver DNA that codes for antibodies isolated from the blood of people infected with HIV. The DNA is incorporated into the muscle cells’ genome and programs the cells to manufacture the antibody, which is then secreted into the bloodstream. The tactic builds on earlier work by scientists at the Children’s Hospital of Philadelphia in Pennsylvania, who in 2009 first described the effectiveness of this technique in preventing transmission of simian immunodeficiency virus, which is similar to HIV but infects monkeys2.
As for the rationale for using gene therapy for HIV: “This is something way out of the ordinary, and it’s perfectly reasonable to say that there’s no reason to do it if there’s an alternative," says Baltimore. "But if there’s no alternative — and that’s where we’re at today — then we should be thinking of new ways to protect people.”
