Isolation and characterization of Marek's disease virus (MDV) cDNAs from a MDV-transformed lymphoblastoid cell line: Identification of an open reading frame antisense to the MDV Eco-Q protein (Meq)

Abstract

Two Marek's disease virus (MDV) cDNAs of 852 and 1168 bp, which map to the right end of the BamHH2 fragment of the MDV genome, were isolated from a cDNA library derived from the MDV transformed lymphoblastoid cell line MKT- 1. These cDNAs hybridized to relatively abundant leftward mRNA transcripts in MKT-1 cells and cells lyrically infected with MDV. The transcriptional initiation site for these transcripts was located in the adjacent BamHI-Q2 fragment, as determined by RNase protection and primer extension assays A computer search for the presence of leftward open reading frames (ORFs) revealed two ORFs encoding 135- and 195-amino-acid polypeptides. A polyclonal antibody raised against a protein sequence in the N-terminus of the latter ORF detected a 23-kDa protein in the nuclear fraction of MDV-transformed lymphoblastoid cells. Furthermore, this ORF was antisense to part of the MDV Eco-Q protein (Meq) sequence.