ABSTRACT
HIV-1 RNA genomes interact with diverse RNA binding proteins in the cytoplasm including antiviral factor APOBEC3G (A3G) that, in the absence of viral Vif proteins, is packaged into virions. When and where genome-A3G interactions are initiated in the host cell is unknown. Here we use quantitative long-term (>24 h) live cell fluorescence video microscopy and a new in-cell RNA-protein interaction assay (the “IC-IP”) to describe subcellular viral and A3G trafficking behaviors over the entire HIV-1 productive phase. Among other findings, we demonstrate that genome-A3G interactions are initiated in the cytosol soon if not immediately after genome nuclear export; that A3G-genome interactions are sufficiently strong so that tethering either factor to membranes inhibits trafficking of the reciprocal binding partner; and that selective recognition of genomes promotes consistent delivery of A3G to sites of virion assembly. Further elucidation of RNA signature(s) detected by A3G may inform development of RNA-targeted antivirals.