Cell biology of retroviral RNA packaging.

Generation of infectious retroviral particles rely on the targeting of all structural components to the correct cellular sites at the correct time. Gag, the main structural protein, orchestrates the assembly process and the mechanisms that trigger its targeting to assembly sites are well described. Gag is also responsible for the packaging of the viral genome and the molecular details of the Gag/RNA interaction are well characterized. Until recently, much less was understood about the cell biology of retrovirus RNA packaging. However, novel biochemical and live-cell microscopic approaches have identified where in the cell the initial events of genome recognition by Gag occur. These recent developments have shed light on the role played by the viral genome during virion assembly. Other central issues of the cell biology of RNA packaging, such as how the Gag-RNA complex traffics through the cytoplasm towards assembly sites, await characterization.