Genomic organization and molecular characterization of porcine cytomegalovirus

A strain of the porcine cytomegalovirus (PCMV), which causes inclusion body rhinitis in newborn piglets, has been characterized with respect to its complete genome sequence. The virus genome is 128,367bp, containing 79 predicted open reading frames (ORFs). Of these ORFs, 69 have counterparts in human herpesvirus 6A (HHV-6A), 6B (HHV-6B) and 7 (HHV-7), and two ORFs are homologous to other members in the subfamily Betaherpesvirinae. Eight ORFs have no homologs in herpesvirus. Homologs had higher identity and possessed similar orientation and location as roseoloviruses. The PCMV genome is a DR-U-DR type, similar to HHV-6A, HHV-6B and HHV-7, but the PCMV DR is shorter and lacks predicted genes and telomere-like sequences. Phylogenetic analyses of several core genes indicate that PCMV could be clustered in a branch with roseoloviruses. We suggest that PCMV could be classified as a member of the genus Roseolovirus of the subfamily Betaherpesvirinae.