Infection Control Today (02/20/12)
Using a mathematical formula that carefully measures the degree to which HIV infection of immune system cells is stalled by antiretroviral therapy, AIDS experts at Johns Hopkins have calculated precisely how well dozens of such anti-HIV drugs work, alone or in any of 857 likely combinations, in suppressing the virus. “Our study results should help researchers and clinicians develop simpler treatments, using either existing or new drugs, for people who are just starting therapy or people who have already tried and developed resistance to another combination,” says senior study investigator and infectious disease specialist Robert Siliciano. Siliciano, a professor at the Johns Hopkins University School of Medicine and a Howard Hughes Medical Institute investigator, and colleagues constructed the measurement tool, called the instantaneous inhibitory potential, or IIP, in the laboratory several years ago by analyzing the shape of drug dose-response curves in human immune system cells infected with HIV. They found that the curves’ steepness reflects the extent to which small increases in the amount of drugs can further suppress attempts by the virus to bounce back, reproduce and spread. Researchers say their latest study findings, published in the journal Nature Medicine online Feb. 19, along with other recent studies, provide valuable information to physicians about the potential strength of different combination drug therapies, and can help in streamlining and tailoring so-called highly active antiretroviral therapy, or HAART, to as few possible drugs as needed.

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