Herpes simplex virus gene products: the accessories reflect her lifestyle well

Herpes simplex virus (HSV) genomic DNA contains at least 74 distinct genes. A set of 40 genes, termed the 'core genes', is commonly found in all herpesviruses; their products include four capsid proteins, six DNA replication proteins, seven DNA packaging/cleavage proteins, four envelope glycoproteins, as well as several others. Although approximately half of the HSV genes are not essential for replication in cell cultures, all accessory gene products are predicted to play indispensable roles for viral replication and dissemination in vivo. Intensive studies have been undertaken to elucidate the functions and roles of HSV gene products, and we are now able to address, at least partially, the biological aspects of all HSV encoded proteins. This article is a brief summary of our present knowledge of the functions and roles of HSV gene products with special attention focused on UL14, UL34, UL51, UL56 and US3, all of which are thought to be involved in HSV egress. Furthermore, efforts are discussed to generate replication-competent HSV lacking a single or multiple accessory gene(s) for potential use in gene therapy or as anti-cancer therapeutics. Finally, specific HSV gene products are being explored as therapeutic agents.