Scientists have found a way to use gene therapy to combat HIV infection.
Although drug therapy has revolutionised the treatment of HIV, it is not curative and inevitably patients still eventually succumb to drug-resistant forms of the virus, treatment-related side effects or cancers such as lymphomas, which occur much more commonly amongst HIV-infected individuals. Part of the reason why HIV is so hard to treat is that the virus lurks inside the human genome, inserting covert copies of its genetic material into the host DNA where it sits out of reach of the effects of drugs or the immune system.
Consequently, in recent years, scientists have been attempting to develop "genetic medicines" that can target this hidden form of the virus. Previous attempts to carry out "gene therapies" in humans, for a range of different diseases, have produced mixed results and are often hard to justify on ethical grounds.
But now a team based in California have provided encouraging evidence that such a strategy might work. Writing in the journal Science Translation Medicine, City of Hope scientist David DiGiusto and his colleagues explain how they have safely and stably genetically modified the immune cells of seven HIV patients to make them resistant to HIV.
The team first collected non-HIV infected blood stem cells from the patients, who were undergoing treatment for lymphoma, a blood cell cancer that occurs more than 100 times more commonly in patients with HIV. Working in the culture dish, the researchers then used a disabled virus to add to the cells several genes that interfere with the growth of HIV.
The cells were then maintained in culture for a further period of time to check that they were safe before they were reinfused back into the patients where they took up residence in the bone marrow and began to produce new blood cells.
Checks on the patients' blood confirmed the presence of cells carrying the anti-HIV genes two years later, when the study ended. This shows that techniques like this can be used safely to protect immune cells from HIV infection.
Next, a much larger study, in which higher counts of modified cells are administered, will be needed to determine whether this technique can aid the elimination of HIV from the body.