Researchers at the National Institute of Allergy and Infectious Diseases (NIAID) have helped answer an important question in the treatment of HIV-infected individuals: why, in patients receiving aggressive antiretroviral therapy who have no easily detectable HIV in their blood, does the virus rapidly rebound to high levels if the drugs are discontinued?

"Our new data suggest that the virus comes roaring back because of the normal stimulatory factors present in the environment of a patient's lymph nodes, notably signalling molecules called cytokines," says Anthony S. Fauci, NIAID Director and Chief of the NIAID Laboratory of Immunoregulation (LIR). "In the absence of antiretroviral therapy, these factors activate HIV that is hiding in a latent form in immune system cells."

In a series of in vitro experiments, the NIAID researchers found that inductive factors can activate reservoirs of latent HIV in resting CD4+ T cells, if potent combinations of antiretroviral drugs are not present. Such drug combinations, which generally include a protease inhibitor and two or three other drugs, are commonly referred to as "highly active antiretroviral therapy" or HAART.

Dr. Fauci's team and two other groups recently demonstrated that reservoirs of latent HIV can be found in resting CD4+ T cells of patients who have taken HAART for many months (see, for i.e., Chun et al., PNAS, Nov. 25 1997). Among Dr. Fauci's new findings are data that suggest that it may prove possible to purge these reservoirs of latent HIV by activating resting, latently infected CD4+ T cells with cytokines, resulting in the death of these cells, while preventing further viral spread with HAART.

Dr. Fauci will pr
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Contact: Greg Folkers
gfolkers@nih.gov
301-496-2263
NIH/National Institute of Allergy and Infectious Diseases
2-Feb-1998