EQUINE INFECTIOUS-ANEMIA VIRUS GAG POLYPROTEIN LATE DOMAIN SPECIFICALLY RECRUITS CELLULAR AP-2 ADAPTER PROTEIN COMPLEXES DURING VIRION ASSEMBLY

We have identified an interaction between the equine infectious anemia virus (EIAV) late assembly domain and the cellular AP-2 clathrin-asso ciated adapter protein complex. A YXXL motif within the EIAV Gag late assembly domain was previously characterized as a sequence critical fo r release of assembling virions. We now show that this YXXL sequence i nteracts in vitro with the AP-50 subunit of the AP-2 complex, while th e functionally interchangeable late assembly domains carried by the Ro us sarcoma virus p2b protein and human immunodeficiency virus type 1 p 6 protein, which utilize PPPY and PTAPP L domains, respectively, do no t bind AP-50 in vitro. In addition, EIAV late domain mutants containin g mutations that have previously been shown to abrogate budding also e xhibit marked decreases in AP-50 binding efficiencies. A role for AP-2 complex in viral assembly is supported by immunofluorescence analysis of EIAV-infected equine dermal cells demonstrating specific colocaliz ation of the alpha adaptin subunit of AP-2 with the EIAV p9 protein at sites of virus budding on the plasma membrane. These data provide str ong evidence that EIAV utilizes the cellular AP-2 complex to accomplis h virion assembly and release.