Purified by immunoaffinity chromatography to ≥ 95% purity as determined by SDS-PAGE, reduced. rgp120 HIV-1 MN conjugated to Colloidal Gold (25nm mean particle size). Coupling Ratio: OD520nm = 10; protein content approximately 25ug. Specificity: Gold conjugated rgp120 binds to murine monoclonal antibodies of defined epitope specificity and human polyclonal antibodies as determined by dot blot assays. Applications: A dose dependent response assay should be performed to determine the optimal concentration for use in specific applications. 1. Dot blot assays may be performed in 1:100 dilution range depending on the concentration of solid phase CD4/Anti-gp120 in the test system. 2. Immunohistochemical studies may be performed in 1:50 dilution range.