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K. Nagashima, S. Rosenfield, D. Thompson, P. Maddon, T. Dragic, and W. Olson*.
Progenics Pharmaceuticals, Inc., Tarrytown and Albert Einstein Coll. of Med., Bronx, NY.
Background:HIV-1 entry proceeds via a cascade of events that provide promising targets for a new generation of antiviral therapies, including the gp120-CD4 attachment inhibitor PRO 542, the gp120-coreceptor inhibitor PRO 140, and the gp41 fusion inhibitors T-20 and T-1249. The multi-step nature of HIV-1 entry leaves the virus highly susceptible to inhibition by combinations of drugs that act at distinct stages of this process. We have shown that double- and triple-drug cocktails of attachment, coreceptor, and fusion inhibitors potently and synergistically block HIV-1 entry over a wide range of experimental conditions in vitro . The present study was performed in order to identify the molecular basis of the observed synergistic interactions.
Methods:HIV-1 membrane fusion was monitored in real time using a semi-automated fluorometric assay, and the inhibitory activities of the individual drugs and drug cocktails were evaluated in time-of-addition, washout, and stepwise temperature-controlled studies.
Results:The data were consistent with a model wherein the drugs act cooperatively to delay the recruitment of a critical number of fusion-active HIV-1 envelope glycoproteins to the site of the fusion pore.
Conclusions:These findings have important implications for the combination use of HIV-1 entry inhibitors in vivo , which may emerge as an important new paradigm for antiviral therapy.
© 8th Conference on Retroviruses and Opportunistic Infections