Cover photograph (Copyright © 2003, American Society for Microbiology. All Rights Reserved.): Expression of herpes simplex virus type 1 (HSV-1) glycoprotein K (gK) on cell surfaces and in Golgi bodies of infected African green monkey kidney (Vero) cells. Most single-amino-acid changes that result in extensive HSV-1-induced cell fusion (syn mutations) occur in gK. Golgi bodies and cell surfaces were stained with wheat germ agglutinin (red), and nuclei were stained with TO-PRO3 (blue). Epitope-tagged gK (green) was detected within Golgi bodies and on juxtaposed cellular surfaces (yellow). This experiment demonstrates that gK is transported via Golgi apparatus-dependent pathways to cell surfaces, where it functions in virus-induced cell fusion. (See related article on page 499.)