Cover photograph (Copyright © 2008, American Society for Microbiology. All Rights Reserved.): Koi herpesvirus (KHV) is the causative agent of a lethal disease in koi and common carp. The study of KHV pathogenesis has been impeded by an inability to produce recombinant viruses, because KHV becomes attenuated during successive passages in culture. These difficulties were overcome by cloning the 295-kb KHV genome as an infectious bacterial artificial chromosome (BAC). The cover picture represents epifluorescent images of viral syncytia induced by the KHV FL BAC strain. The red signal represents detection of a KHV nuclear antigen, while the green signal represents virally encoded enhanced green fluorescent protein (EGFP). Colocalization of nuclear antigen and EGFP in syncytia is shown in yellow. The two circling koi symbolize the BAC. (See related article on p. 4955.)