HIV-2 gp39 is a viral envelope glycoprotein associated with the envelope protein complex of Human Immunodeficiency Virus Type 2 (HIV-2). As an envelope-associated antigen, gp39 contributes to the structure and function of the viral surface and is involved in interactions between the virus and host cells. Antibodies targeting HIV-2 gp39 can therefore serve as valuable tools for studying HIV-2 envelope proteins, viral structure, antigenicity, and host–virus interactions.

HIV-2 gp39 antibodies are used in research applications including the detection and characterization of HIV-2 envelope proteins, immunological studies, and the development and evaluation of diagnostic or analytical assays. Depending on the antibody's specificity and validated application, it may be suitable for techniques such as immunoblotting, ELISA, immunoprecipitation, or other immunoassay formats.

Because HIV-2 differs antigenically from HIV-1, antibodies specific to HIV-2 envelope proteins can be particularly useful for investigating HIV-2-specific antigenic properties and for distinguishing HIV-2-related viral components in research and assay development.