We recently discovered that the natural compound sulforaphane (SFN), found abundantly in cruciferous vegetables, blocks HIV-1 and -2 infections of primary macrophages. It also blocks infection of macrophage- like cell lines. It does not however stop infection of primary T cells. The objective of this application is to determine how SFN hinders HIV so that we can learn how best to apply this or related compounds therapeutically, perhaps even expanding the antiviral action to additional cell types. The central hypothesis is that sulforaphane treatment triggers, through NRF2, expression of a cellular protein that blocks HIV infection in macrophages after viral entry but before viral gene expression. This hypothesis is based on our observation that SFN reduces expression of virus-encoded reporters after either HIV Env or VSV-G- mediated entry. The rationale for the proposed research is that once we understand what SFN treatment does to the virus and what SFN needs to function in a cell, we can begin to identify the specific mechanism through which it blocks infection and explore the use of SFN in therapeutic applications. Two specific aims will be used to test the central hypothesis: 1) To determine the physical impact of SFN treatment on HIV in macrophages; 2) To establish cellular requirements for SFN-mediated restriction to HIV infection. The proposed work is innovative because this is the first time that the natural compound SFN is being explored as an antiviral agent in macrophages. The research is significant because SFN is unlike other antiviral compounds currently in use and is therefore likely to shed light on new opportunities to interfere with infection.