The war against AIDS is one of attrition. Antiretroviral drugs can slow the proliferation of the human immunodeficiency virus, delaying the day when the patient experiences full-blown AIDS. But they do not eliminate the virus, which can revive lethally after lying dormant for decades. Now an experimental gene therapy has emerged that may come a little closer toward actually curing AIDS. It works by turning HIV's own virulence against itself. The new therapy, produced by the small biotech firm Virxsys of Gaithersburg, Md., embeds a genetically engineered weapon called a lentiviral vector in the body's own disease-fighting T cells. (A vector is something that transfers genetic material into a cell; in this case it is a defanged version of HIV itself.) …
