[The mechanisms of human cytomegalovirus DNA replication]

Human cytomegalovirus (HCMV) is a human herpesvirus with a linear double stranded DNA which have the largest genomes, about 230 kbp in length, of any of the herpesviruses. The replication of HCMV DNA initiated from HCMV DNA replication origin (oriLyt) and formed concatemers by rolling circule-type replication. The genome inversions of the L and S components occur within concatemeric DNA and formed four isomeres. Then, the concatemeric DNA is cleaved to a unit length at the termini with the "a" sequence as a cis-acting signal and packaged into preformed capsids in the nucleus. Six HCMV genes common to herpesvirus group encode essential proteins that constitute the replication fork complex. In addition, five viral genes are required for efficient DNA replication as trans-acting factors. Several HCMV genes are HSV homologs involved in nucleotide metabolism and DNA repair.