U.S. Experiment Uses AIDS to Fight AIDS

A phase I safety and feasibility study using five HIV-positive patients who were beginning to fail treatment found a promising patient-specific genetic approach to fighting the virus.

Dr. Carl June, lead author from the University of Pennsylvania School of Medicine, and colleagues first crippled HIV. "The virus is gutted so that it only has half the size of the original or pathogenic virus," he said. The envelope gene remaining is reversed to express an antisense gene, an anti-HIV envelope gene. June's team then removed samples of each patient's CD4 T-cells, which HIV targets, infused those cells with the genetically engineered antisense HIV, and infused the antisense HIV-infected CD4 T-cells back into the same patients.

The result was that newly infected immune cells began pumping out defective virus. "The particles that are released are, like, sterile. They are nonpathogenic," said June. And three years later, not only are none of the patients showing adverse effects, the immune systems of four patients actually improved. The virus remains partly suppressed.

"It seemed to have a vaccine-like effect in that the immune system was better in most of the patients than when they were enrolled," said June. "We are trying to study the mechanism." "We put back more [CD4 cells] than we took out. We don't know if that is why their immune system gets better, because there are more soldiers, or whether it got better because of better antiviral effects."

Phase II trials in HIV patients with well-controlled virus are now underway, said June. It is still not certain whether the approach could be useful only in infected patients, or someday prove to be prophylactic for HIV-negative individuals, said June.

The candidate therapy is being developed by Gaithersburg, Md.-based VIRxSYS Corp. The studies are partly funded by the National Institute of Allergy and Infectious Diseases.

The full open-access report, "Gene Transfer in Humans Using a Conditionally Replicating Lentiviral Vector," was published online in Proceedings of the National Academy of Sciences-USA (2006;doi:10.1073/pnas.0608138103).

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