Blips have caused considerable concern among clinicians and patients, who thought that they could signal either the development of drug resistance by the virus or reduced drug efficacy. Such concerns have led to patient anxiety, costly repeat testing, or unnecessary alterations in therapy, said the researchers.

A research team led by Robert F. Siliciano, a Howard Hughes Medical Institute investigator at Johns Hopkins, published its findings in the February 16, 2005, issue of the Journal of the American Medical Association. Siliciano and his colleagues at Hopkins collaborated on the studies with researchers from the Bloomberg School of Public Health at Johns Hopkins, and the National Institute of Allergy and Infectious Diseases.

Highly active antiretroviral therapy (HAART) has been successful at suppressing HIV, enormously reducing viremia, which is a measure of the concentration of viral particles in the bloodstream, said Siliciano. "The goal of treatment now is to suppress viremia below fifty copies per milliliter, which is the limit of detection of the best available assays," he said. "It's pretty clear that if viremia is consistently above that level, drug resistance -- the overwhelming problem in HIV infection -- will develop. It's also pretty clear that if a patient is below fifty copies and doing well, that drug resistance doesn't develop."

Resistance arises because the proliferating virus evolves molecular changes that evade the suppressive effects of the drugs. "So, when a clinician suddenly sees a measurement of one hundred and twenty (copies), the clinician and the p
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Contact: Jim Keeley
keeleyj@hhmi.org
301-215-8858
Howard Hughes Medical Institute
15-Feb-2005