The recognition that some individuals are resistant to HIV by virtue of having a mutation in the chemokine receptor, CCR5, has proven the role of this receptor in the HIV infection. The goal of this research is to develop a peptide antagonist for HIV entry using the highly degenerate oriented peptide labrary method. CCR5 will be expressed and purified. Highly diverse peptide libraries will be synthesized and allowed to interact with CCR5. From the sub-population of peptides binding to CCR5, the properties of the active site will be deduced. Finally peptides will be synthesized and their affinity for CCR5 determined. PROPOSED COMMERCIAL APPLICATIONS: Our goal is an injectable pharmaceutical consisting of a peptide that will bind to the chemokine receptor CCR5 and block the ability of HIV to enter T lymphocytes. The peptide will be offered as a controlled release formulation permitting infrequent injection.