Marek's disease virus latency.

MDV latency is defined as the persistence of the viral genome in the absence of production of infectious virus except during reactivation. A number of systems for studying MDV latency exist, and most involve the use of lymphoblastoid cells or tumors. It has been difficult to divorce latency and transformation.

Marek's disease virus latency-associated transcripts belong to a family of spliced RNAs that are antisense to the ICP4 homolog gene.

Marek's disease virus (MDV) latency-associated transcripts include at least two MDV small RNAs (MSRs) and a 10-kb RNA which map antisense to the ICP4 homolog gene and are relatively abundant in MDV-transformed lymphoblastoid cells. This report further describes the biological and structural properties of these RNAs. First, these RNAs were detected in primary lymphomas isolated from chickens infected with several oncogenic MDV strains.

Identification of latency-associated transcripts that map antisense to the ICP4 homolog gene of Marek's disease virus.

Two small RNAs (0.9 and 0.75 kb), named Marek's disease virus (MDV) small RNAs (MSRs) and a 10-kb RNA, all of which map antisense to the MDV ICP4 homolog gene, have been readily detected in MDCC-MSB1 MDV-transformed T-lymphoblastoid cells.

Enhanced expression of the Marek's disease virus-specific phosphoproteins after stable transfection of MSB-1 cells with the Marek's disease virus homologue of ICP4.

Phosphoprotein pp38, coded for by the BamHI-H fragment of the Marek's disease herpesvirus (MDV) genome is expressed in tumor cells and tumor cell lines. pp38 is associated with two other phosphoproteins, pp41 and pp24, and can be detected in a small percentage of tumor cells by indirect immunofluorescence assays (IIFA). The importance of MDV ICP4 for the regulation of pp38 expression was examined in the following MSB-1-derived cell lines stably transfected with the selection plasmid pNL1 [MDCC-CU221 (CU221)], pNL1 and the BamHI-A fragment of MDV DNA containing ICP4 (CU224), MDV ICP4 inserted in antisense direction in the eukaryotic expression vector pXT1 (CU222), or ICP4 in sense direction in pXT1 (CU223) or cotransfected with pNL1 and EcoRI-linearized BamHI-A MDV DNA (CU225, -237, -243, -244).