Gene arrangement and RNA transcription of the BamHI fragments K and M2 within the non-oncogenic Marek's disease virus serotype 2 unique long genome region.

摘要

We determined the nucleotide sequence of a 6593 bp fragment of the Marek's disease virus serotype 2 (MDV2) unique long region located in the right part of genomic BamHI-M2 and the adjacent part of BamHI-K fragments. Within this region five complete open reading frames (ORFs) were identified whose deduced amino acid sequences exhibited homology to the UL53 (glycoprotein K), UL54 (immediate early regulatory protein ICP27), and UL55 gene products of herpes simplex virus type 1 (HSV-1). Homologue to the HSV-1 UL56 was not detected. However, we identified a gene between the MDV2 UL54 and UL55 genes with homology to the first ORF (ORF-1) of equine herpesvirus type 1 and corresponding gene identified in pseudorabies virus. Two adjacent ORFs contained in the BamHI-K fragment, ORF 873s and ORF 873, were found by computer analysis to have the properties of an intron encoding a glycoprotein: ORF 873s encodes a 84 amino acid polypeptide with a stretch of a hydrophobic signal sequence in the C-terminus, and ORF 873 encodes a 873 amino acid polypeptide with a transmembrane domain and putative three N-linked glycosylation sites. All the identified genes were confirmed to be transcribed with 3'-coterminal transcripts and/or a unique transcript in the virus-infected cells. Especially, 3.5 kb mRNA of ORF 873s and ORF 873 are transcribed from a potential promoter region of ORF 873s, and splice donor and acceptor sites are used to splice the mRNA after cleavage of a 113 bp-nucleotide sequence.