title: Identification of an intercistronic internal ribosome entry site in a Marek's disease virus immediate-early gene.
abstract: In this study, we have identified an internal ribosome entry site (IRES) from the highly infectious herpesvirus Marek's disease virus (MDV). The IRES was mapped to the intercistronic region (ICR) of a bicistronic mRNA that we cloned from the MDV-transformed CD4(+) T-cell line MSB-1. The transcript is a member of a family of mRNAs expressed as immediate-early genes with two open reading frames (ORF). The first ORF encodes a 14-kDa polypeptide with two N-terminal splice variants, whereas the second ORF is contained entirely within a single exon and encodes a 12-kDa protein also known as RLORF9. We have shown that the ICR that separates the two ORFs functions as an IRES that controls the translation of RLORF9 when cap-dependent translation is inhibited. Deletion analysis revealed that there are two potential IRES elements within the ICR. Reverse genetic experiments with the oncogenic strain of MDV type 1 indicated that deletion of IRES-controlled RLORF9 does not significantly affect viral replication or MDV-induced mortality.
authors.affiliation: Division of Microbiology, Institute for Animal Health, Compton, Berkshire, United Kingdom. abdou.tahiri-alaoui@bbsrc.ac.uk
authors.forename: Abdessamad
authors.initials: A
authors.lastname: Tahiri-Alaoui
authors.forename: Lorraine P
authors.initials: LP
authors.lastname: Smith
authors.forename: Suzan
authors.initials: S
authors.lastname: Baigent
authors.forename: Lydia
authors.initials: L
authors.lastname: Kgosana
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Petherbridge
authors.forename: Luke S
authors.initials: LS
authors.lastname: Lambeth
authors.forename: William
authors.initials: W
authors.lastname: James
authors.forename: Venugopal
authors.initials: V
authors.lastname: Nair
mesh_terms: D000818:Animals; D002460:Cell Line; D002645:Chickens; D021901:DNA, Intergenic / Q000235:genetics*; D017353:Gene Deletion; D015967:Gene Expression Regulation, Viral; D016679:Genome, Viral / Q000235:genetics; D017874:Immediate-Early Proteins / Q000235:genetics* / Q000378:metabolism*; D025922:Mardivirus / Q000235:genetics* / Q000378:metabolism*; D008380:Marek Disease; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D021901:DNA, Intergenic; D017874:Immediate-Early Proteins