Slipping through the door: HIV entry into the nucleus.

HIV infection of non-dividing cellular targets like macrophages requires successful passage of the viral preintegration complex (PIC) across an intact nuclear envelope. Unique but redundant nuclear import signals reside within the HIV integrase, matrix, and Vpr proteins as well as the 'DNA flap'; these signals appear to facilitate PIC transport through the limiting nuclear pores. We discuss recent studies that have advanced our understanding of this key step in the HIV life cycle.