Structural analysis and transcriptional mapping of the Marek's disease virus gene encoding pp38, an antigen associated with transformed cells

Abstract

The gene encoding a Marek's disease virus (MDV) pp38 phosphoprotein has been identified, sequenced, and localized to the BamHI H fragment to the left of the putative MDV origin of replication. The open reading frame was defined by sequencing of a lacZ-pp38 fusion protein gene from a Agt 1 expression library. The entire open reading frame is 290 amino acids long and codes for a protein with a calculated molecular weight of 31,169, compared with the size of 38 kDa of the phosphorylated form estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Si nuclease protection analysis showed that the pp38 gene is transcribed leftward as an unspliced mRNA. On the basis of transcriptional mapping studies, the pp38 transcript is predicted to be about 1.8 kb in length without a poly(A) sequence. Its promoter-enhancer region overlaps that of the major rightward BamHI H 1.8-kb transcript implicated in tumor induction. This region

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

“…4B). In contrast, the 1.8-kb MDV pp38 transcript (13,16) was found in the cytoplasmic RNA fraction, as expected (Fig. 4C).…”

Expression of the Marek's disease virus (MDV) homolog of glycoprotein B of herpes simplex virus by a recombinant baculovirus and its identification as the B antigen (gp100, gp60, gp49) of MDV

“…After determining the nucleotide sequence of the left half of the BamHI H fragment, where the B antigen gene was reported to be localized, we could not find a single open reading frame which is long enough to encode the 44-kDa peptide reported by Sithole et al (57) as a precursor (data not shown). Very recently, Cui et al (15) identified the gene encoding pp38 of MDV on the BamnHI H fragment, where the B antigen gene was reported to be localized (57). These findings strongly support our identification of the gB homolog as the B antigen.…”

Status of Marek's disease virus in established lymphoma cell lines: herpesvirus integration is common

“…Length polymorphism of restriction fragments between oncogenic and nononcogenic strains, as well as attenuated strains obtained by serial in vitro passage, has prompted efforts to identify genes that may be associated with tumorigenicity (6,7,18,19,61). In an alternative approach, viral gene products expressed in MDV-transformed cells were identified by characterizing mRNAs or by cDNA cloning techniques (6,13,40,56,62) or by monoclonal antibodies (14,15,30,45). One property of MDVtransformed cells has made it extremely difficult to analyze potential tumor-associated transcripts unambiguously; a few cells in a tumor or in an established cell line in which the virus undergoes the lytic cycle will make the obtained data difficult to interpret.…”