Interferon-gamma is associated with the surface of the human immunodeficiency virus and binds to the gag gene product p17.

Purified HIV-1 antigen preparations produced in cell culture were found to contain interferon-gamma (IFN-gamma). Electron microscopic examination of HIV-1 released by H9 cells, a cell line found to produce IFN-gamma, showed the presence of this molecule on the surface of the virus particle. The HIV-1 protein p17 was found to bind IFN-gamma by a solid-phase radioimmunoassay. The specificity of the reaction was confirmed by Western blot analysis. This finding opens new questions about the biologic role of IFN-gamma itself and of its interaction with HIV.