Isolation and Characterization of Marek's Disease Virus (MDV) cDNAs Mapping to theBamHI-I2,BamHI-Q2, andBamHI-L Fragments of the MDV Genome from Lymphoblastoid Cells Transformed and Persistently Infected with MDV

Abstract

We have isolated and sequenced two cDNAs of sizes 2674 and 677 bp from a cDNA library derived from MKT-1, a lymphoblastoid cell line transformed and latently infected with Marek's disease virus (MDV) using probes corresponding to the right-hand end of theBamHI-I2fragment of the MDV genome. The larger cDNA clone represents an abundant transcript, which extends from the right-hand end ofBamHI-I2to the adjacentBamHI-Q2andBamHI-L fragments of the MDV genome and contains the Meq (MDVEco-Q) open reading frame. The smaller cDNA clone represents a spliced transcript containing the putative DNA binding domain of Meq as well as sequences in theBamHI-L region. We prepared a polyclonal antibody against part of the protein sequence of Meq and detected a 44-kDa protein in MKT-1 cells and in cells lytically infected with MDV. In addition, riboprobes corresponding to sequences specific to each cDNA as well as shared sequences between cDNAs detected a number of transcripts in cells either lytically or latently infected with MDV. Our results indicate that the Meq transcriptional unit extends to theBamHI-L fragment and that the transcripts mapping to the right-hand end of theBamHI-I2and adjacentBamHI-Q2andBamHI-L fragments are not preferentially expressed during latency. © 1995.