title: Analysis of transcriptional activities of the Meq proteins present in highly virulent Marek's disease virus strains, RB1B and Md5.
abstract: Marek's disease virus (MDV) is an oncogenic herpesvirus that causes malignant lymphomas in chickens. Recent field isolates of MDV have tended to exhibit increasing virulence, and MDV strains are currently classified into four categories based on their relative virulence. Meq, a putative MDV oncoprotein, resembles the Jun/Fos family of basic leucine zipper (bZIP) transcription factors and can regulate the expression of viral and cellular genes as a homodimer or as a heterodimer with a variety of bZIP family proteins. MDV isolates display distinct diversity and point mutations in Meq, which may contribute to changes in the transcriptional activities of Meq and subsequently, to observed increases in MDV oncogenicity. In this study, we introduced mutations into the meq gene and used dual luciferase reporter assays to analyze the transcriptional activities of the resulting Meq proteins to determine whether distinct mutations in Meq could be responsible for differences in transcriptional activity among MDV strains. A proline-to-alanine substitution at position 217, the second position of one of the proline direct repeats in the transactivation domain, enhanced the transactivation activity of Meq. In addition, we found that two substitutions at positions 283 and 320 affected transactivation activity. These results suggest that the distinct diversity of and point mutations in the Meq proteins are responsible for differences in transactivation activity among MDV strains.
authors.affiliation: Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18, Nishi-9, Kita-ku, Sapporo, 060-0818, Japan. murata@vetmed.hokudai.ac.jp
authors.forename: Shiro
authors.initials: S
authors.lastname: Murata
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Okada
authors.forename: Rika
authors.initials: R
authors.lastname: Kano
authors.forename: Yuko
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Hashiguchi
authors.forename: Misao
authors.initials: M
authors.lastname: Onuma
authors.forename: Satoru
authors.initials: S
authors.lastname: Konnai
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ohashi
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D002645:Chickens; D015967:Gene Expression Regulation, Viral; D025922:Mardivirus / Q000235:genetics / Q000502:physiology*; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D009856:Oncogene Proteins, Viral / Q000235:genetics / Q000378:metabolism*; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: C100369:Eco-Q protein, Gallid herpesvirus 2; D050505:Mutant Proteins; D009856:Oncogene Proteins, Viral; D037521:Virulence Factors