This project uses MAPPIT (Mammalian Protein-Protein Interaction Trap)to study known interactions between HIV-1 and host proteins and identifies new interactions between the two. We use a MAPPIT-based mutagenesis approach and a newly developed MAPPIT-based screening strategy to map the interaction domain for a number of protein interactions including Apobec3G-Vif and Apobec3G-gag. Array MAPPIT allows us to screen for new protein interactions.