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Updated: Aug 14, 2026
Vaccinia Virus Infection & Temporal Analysis of Virus Gene Expression: Part 2
Published on: April 10, 2009
Structural analysis and transcriptional mapping of the Marek's disease virus gene encoding pp38, an antigen
1Avian Disease and Oncology Laboratory, USDA Agricultural Research Service, East Lansing, Michigan 48823.
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 lambda gt11 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. S1 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 contains Oct-1, Sp1, and CCAAT motifs as well as the putative origin of replication. The pp38 protein is the only presently known antigen that is consistently associated with the transformation state. It may play a significant role in MDV transformation.
Insights
Researchers identified the Marek's disease virus (MDV) pp38 phosphoprotein gene, crucial for viral transformation. This antigen is consistently linked to the transformation state, suggesting a significant role in MDV-induced tumors.
Area of Science:
- Virology
- Molecular Biology
- Oncology
Background:
- Marek's disease virus (MDV) is a significant oncogenic avian pathogen.
- Understanding viral oncogenes is critical for developing effective control strategies.
Purpose of the Study:
- To identify, sequence, and characterize the gene encoding the MDV pp38 phosphoprotein.
- To investigate the role of the pp38 protein in MDV-induced cell transformation.
Main Methods:
- Gene sequencing and characterization (open reading frame, molecular weight).
- Gene localization using restriction enzyme mapping (BamHI H fragment).
- Transcriptional analysis (S1 nuclease protection, Northern blotting).
Main Results:
- The pp38 gene was localized to the BamHI H fragment, near the origin of replication.
- The pp38 open reading frame is 290 amino acids, coding for a 31 kDa protein (phosphorylated form is 38 kDa).
- The pp38 gene is transcribed leftward as an unspliced 1.8 kb mRNA, with a promoter overlapping a tumor-associated transcript.
Conclusions:
- The pp38 protein is the sole known antigen consistently associated with the MDV transformation state.
- pp38 likely plays a significant role in Marek's disease virus-induced tumor formation.
