unreceptive welcome. CripplingCCR5 receivers can block cell doors to HIV.
Illustration by Katharine Sutliff / Science
Last year, a man from Berlin, Timothy Brown, became world famous as the first and so far only person to have been apparently cured of his HIV infection. Brown HIV disappeared after developing leukemia and doctors gave him repeated blood transfusions from a donor who harbored a mutated version of a receiver virus uses to enter cells. Now, researchers are reporting promising results from two smaller gene therapy studies that mimic this strategy, hinting that the field can move closer to a cure that works for the masses.
At the Interscience Conference on Antimicrobial Agents and Chemotherapy in Chicago, Illinois, this weekend, researchers reported preliminary results of the tests of a new treatment in 15 people infected with HIV developed to free them from the need to take antiretroviral drugs. The studies, conducted separately on the East and West coasts of the United States, trying to make the immune system resistant to HIV by paralyzing a receptor called CCR5 on T cells that the virus uses during the infection process. The man who donated blood for transfusions Timothy Brown had naturally defective CCR5 receptor.
The trial participants had T cells taken from their blood and then modified in the laboratory with a design by Sangamo BioSciences enzyme designed in Richmond, California. The enzyme known as a zinc finger nuclease, the clips of the gene encoding the CCR5 receptor and off. Ten billion modified cells were then injected back into the body of the participants, and the new data show that about 25% of cells had the mutant CCR5s. Studies have shown that modified T cells persisted for more than 6 months in several patients.
In a provocative case reported in Chicago yesterday, a patient who received gene therapy, then stopped taking antiretroviral drugs had back HIV in a month, as usually happens when people stop treatment . But a few weeks later, the virus began to decline, and it fell to undetectable levels together with proof that gene therapy has changed its T cell "These kinetics are very different from what I saw in the treatment interruption studies, and we did a lot, "said Pablo Tebas, a clinical infectious diseases at the University of Pennsylvania, who is leading the study of the East coast of six participants." the patient goes to down, down. "
Tebas acknowledges that his study is uncontrolled and they saw the response in one patient. in addition, the patient already had a natural advantage because it has a gene paralyzed CCR5 in one of the two copies he inherited. Tebas suspect gene therapy associated with its natural CCR5 mutation combined to lead to spectacular results. "This is a very small experience, and I do not think it's a cure by any means, but the Berlin patient is a single patient, and changed research priorities, "said Tebas. "This shows that there is a correlation between the antiviral activity and the proportion of modified cells. It shows the way forward."
Although researchers do not provide gene therapy to completely clear HIV from the body, they hope to create a "functional cure", that contain the virus to such a powerful extent that people no longer need antiretrovirals.
virologist David Margolis, which conducts its own HIV cure studies at the University of North Carolina, Chapel Hill, said many questions remain about the impact of this gene therapy, however. "These data are interesting and encouraging, but still incomplete," he said. Still, Margolis is "impressed" by the percentage of cells that were artificially modified CCR5 gene.
Even if this gene therapy is revealed, the challenge of cost and technical intervention means that it will probably unlikely to be used outdoors in rich countries. But Tebas noted that the cost of antiretrovirals is also high and that any calculation would balance against each other.
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