Lens epithelial derived growth factor (LEDGF/p75) is a host protein that binds to integrase and is crucial for viral replication. The mechanism of action is not precisely known but evidence suggest that LEDGF/p75 guides integrase to insert viral DNA into transcriptionally active sites of the host genome. Inhibitors of this protein are already being developed and patented. They are likely to be highly target specific and less prone to the development of resistance.