Evaluation of the lytic origins of replication of Kaposi's sarcoma-associated virus/human herpesvirus 8 in the context of the viral genome.

The lytic origins of DNA replication for human herpesvirus 8 (HHV8), oriLyt-L and oriLyt-R, are located between open reading frames K4.2 and K5 and ORF69 and vFLIP, respectively. These lytic origins were elucidated using a transient replication assay. Although this assay is a powerful tool for identifying many herpesvirus lytic origins, it is limited in its ability to evaluate the activity of replication origins in the context of the viral genome. To this end, we investigated the ability of a recombinant HHV8 bacterial artificial chromosome (BAC) to replicate in the absence of oriLyt-R, oriLyt-L, or both oriLyt regions. We generated the HHV8 BAC recombinants (BAC36-DeltaOri-R, BAC36-DeltaOri-L, and BAC36-DeltaOri-RL), which removed one or all of the identified lytic origins. An evaluation of these recombinant BACs revealed that oriLyt-L was sufficient to propagate the viral genome, whereas oriLyt-R alone failed to direct the amplification of viral DNA.