Cover photograph (Copyright © 2006, American Society for Microbiology. All Rights Reserved.): 293T cells transduced with hCD8α and C-terminal hemagglutinin-tagged hCD8β were subsequently transfected with a construct expressing a PPAA mutant of the human immunodeficiency virus type 1 NefNA-7 protein fused to a green fluorescent reporter protein. NefPPAA.EGFP (green) and CD8β.HA (red) were detected by fluorescence; areas of colocalization are shown in yellow. Nuclei were visualized by DAPI staining (blue). Like wild-type Nef, Nef mutant PPAA is able to downregulate surface expression of the CD8αβ receptor. (See related article in September 2005: vol. 79, issue 17, p. 11422.)