Herpes Treatments

Kaposi’s sarcoma-associated herpesvirus ori-Lyt-dependent DNA replication: cis-acting requirements for replication and ori-Lyt-associated RNA trans… – PubMed


The relationship between herpes simplex virus (HSV) DNA replication and establishment of latent infection was examined using an experimental model that makes use of the segmental sensory innervation of mouse flanks (T7 to T12). Here we assessed three parameters that may enhance the efficacy of a gD DNA vaccine in cattle. To map cis-acting elements within KSHV ori-Lyt that are required for DNA replication function and to define the nature of K8 bZip protein binding to the origin, we constructed consecutive internal deletion mutations across the core domain of a KSHV ori-Lyt and tested them for DNA replication function in a transient replication assay. In this report, we demonstrated that DNA sequences in two noncoding regions of the Kaposi’s sarcoma-associated herpesvirus (KSHV) genome, between open reading frames (ORFs) K4.2 and K5 and between K12 and ORF71, are able to serve as origins for lytic cycle-specific DNA replication. The first component contains eight CCAAT/enhancer binding protein (C/EBP) binding motifs that organize as four spaced C/EBP palindromes. A threshold of HSV DNA levels equal or higher than 5.0 log (n = 7) was associated with mortality within 28 days following hospital admission (odds ratio [OR], 6.8; 95% confidence interval [CI], 1.2-39.2). (iii) Electron microscopic studies indicated that the DNA extracted from cells replicating viral DNA and banding at the density of viral DNA contained: (a) linear, full-size molecules with internal gaps and single-stranded regions at termini; (b) molecules with lariats, consisting of a linear segment up to 2× the size of mature DNA and a ring ranging from 0.5 × 106 to 100 × 106 in molecular weight, showing continuous and discontinuous forks; (c) circular, double-stranded molecules, both full-size and multiples of 18 × 106 in molecular weight, but without forks or loops; (d) molecules showing “eye” and “D” loops at or near one end of the DNA; (e) large, tangled masses of DNA, similar to those observed for T4 and pseudorabies virus replicating DNAs, containing loops and continuous and discontinuous forks.

Our data do not support a causal role of either HHV-8 or a novel herpesviral variant related to HHV-8 in MM. The third component was determined to be a 32-bp previously unidentified sequence and is required for DNA replication. The last component consists of an open reading frame 50 (ORF50)/Rta responsive element (RRE) and a TATA box. We showed that the binding of an ORF50/Rta protein to the RRE was essential for ori-Lyt-dependent DNA replication. The presence of a functional RRE and a downstream TATA box suggested that this region serves as an ORF50/Rta-dependent promoter and a transcription event may be necessary for ori-Lyt-dependent DNA replication. Using a luciferase reporter system, we demonstrated that the region of the RRE and TATA box constitutes an ORF50/Rta-dependent promoter. Furthermore, a polyadenylated RNA of 1.4 kb was identified downstream of the promoter.