Introduction

Taxonomy aims to structure relationships among diverse organisms in order to provide a broader understanding of Nature than is afforded by consideration of organisms in isolation. Since biological systems are shaped by evolution, which is not influenced by the human desire to impose order, any taxonomical scheme is bound to be incomplete and to some extent arbitrary. The criteria applied are necessarily confined to what is technically possible, and thus taxonomy has an important historical component. In addition, taxonomy develops conservatively, since striving for the ideal must be tempered by the need to maintain utility. It is also an unfortunate fact that taxonomy provides fertile soil for debate among a few but is of little interest to most. However, it is beyond dispute that the setting of herpesviruses in a taxonomical framework is vital for understanding the origins and behavior of this fascinating family of organisms.

Historically, herpesvirus taxonomy has been addressed since 1971 by the International Committee on Taxonomy of Viruses (ICTV) (Wildy, 1971). A provisional approach to endowing herpesviruses with formal names (Roizman et al., 1973) was followed by grouping into subfamilies largely on the basis of biological criteria (Roizman et al., 1981). This effort was rather successful, but not free from what turned out in hindsight to be a few misclassifications (Roizman et al., 1992). Further division of the subfamilies into genera utilized molecular data to a greater extent than before, primarily in relation to genome characteristics such as size and structure (Roizman et al., 1992).