Cover photograph (Copyright © 2003, American Society for Microbiology. All Rights Reserved.): Simian immunodeficiency virus (SIV)-infected cells in lymph nodes. Two weeks after infection of rhesus macaques with SIVmac239, most SIV-infected cells (green) were localized in the T-cell-rich paracortex of the lymph nodes and not in the B-cell-rich follicles (red). (See related article in April 2003: vol. 77, issue 7, p. 4169.)