DETERMINATION AND ANALYSIS OF THE COMPLETE NUCLEOTIDE-SEQUENCE OF HUMAN HERPESVIRUS-7

Human herpesvirus 7 (HHV-7) is a recently isolated betaherpesvirus tha t is prevalent in the human population, with primary infection usually occurring in early childhood. HHV-7 is related to human herpesvirus 6 (HHV-6) in terms of both biological and, from limited prior DNA seque nce analysis, genetic criteria. However, extensive analysis of the HHV -7 genome has not been reported, and the precise phylogenetic relation ship of HHV-7 to the other human betaherpesviruses HHV-6 and human cyt omegalovirus has not been determined. Here I report on the determinati on and analysis of the complete DNA sequence of HHV-7 strain JI. The d ata establish that the close biological relationship of HHV-6 and HHV- 7 is reflected at the genetic level, where there is a very high degree of conservation of genetic content and encoded amino acid sequences. The data also delineate loci of divergence between the HHV-6 and HHV-7 genomes, which occur at the genome termini in the region of the termi nal direct-repeat elements and within limited regions of the unique co mponent, Of potential significance with respect to biological and evol utionary divergence of HHV-6 and HHV-7 are notable structural differen ces in putative transcriptional regulatory genes specified by the dire ct-repeat and immediate-early region A loci of these viruses and the a bsence of an equivalent of the HHV-6 adeno-associated virus type 2 rep gene homolog in HHV-7.