Evolutionary aspects of oncogenic herpesviruses

Several of the gamma-herpesviruses are known to have cellular transforming and oncogenic properties. The genomes of eight distinct gamma-herpesviruses have been sequenced, and the resulting database of information has enabled the identification of genetic similarities and differences between evoluti onarily closely related and distant viruses of the subfamily and between th e gamma-herpesviruses and other members of the herpesvirus family. The reco gnition of coincident loci of genetic divergence between individual gamma-h erpesviruses and the identification of novel genes and cellular gene homolo gues in these genomic regions has delineated a subset of genes that are Lik ely to contribute to the unique biological proper ties of these viruses. Th ese genes, together with gamma-herpesvirus conserved genes not found in vir uses outside the family, might be responsible for virus specific pathogenic ity and pathogenic effects, such as viral associated neoplasia, characteris tic of the subfamily. The presence of the gamma-herpesvirus major divergent genomic loci and the apparent increased mutational frequencies of homologo us genes where they occur) within these regions, indicates that these loci possess particular features that drive genetic divergence. Whatever the mec hanisms underlying this phenomenon, it potentially provides the basis for t he relatively rapid adaptation and evolution of gamma-herpesviruses and the diversity of biological and pathogenic properties.