Characterization of the regulatory functions of the equine herpesvirus 1 immediate-early gene product

• Published in: Journal of Virology 1992-02, Vol.66 (2), p.936-945
• Main Authors: Smith, R.H. (Louisiana State University Medical Center, Shreveport, LA), Caughman, G.B, O'Callaghan, D.J
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Chloramphenicol O-Acetyltransferase - genetics; Chloramphenicol O-Acetyltransferase - metabolism; Cloning, Molecular; EXPRESION GENICA; EXPRESSION DES GENES; Fundamental and applied biological sciences. Psychology; GENE; Gene Expression Regulation, Viral; GENES; Genes, Viral; Genetic Vectors; GENETICA; Genetics; GENETIQUE; Herpesvirus 1, Equid - genetics; HERPESVIRUS EQUIN; HERPESVIRUS EQUINO; L Cells (Cell Line); Mice; Microbiology; Plasmids; Promoter Regions, Genetic; PROTEINAS; PROTEINE; Restriction Mapping; Trans-Activators - genetics; Transfection; Viral Proteins - genetics; Virology
• ISSN: 0022-538X; 1098-5514
• DOI: 10.1128/jvi.66.2.936-945.1992

Use of the translation-inhibiting drug cycloheximide has indicated that the equine herpesvirus 1 (EHV-1) immediate-early (IE) gene, the sole EHV-1 IE gene, encodes a major viral regulatory protein since IE mRNA translation is a prerequisite for all further viral gene expression (W. L. Gray, R. P. Baumann, A. T. Robertson, G. B. Caughman, D. J. O'Callaghan, and J. Staczek, Virology 158:79-l87, 1987). An EHV-1 IE gene expression vector (pSVIE) in combination with chimeric EHV-1 promoter-chloramphenicol acetyltransferase CAT) reporter constructs was used in transient transfection assays to characterize the regulatory functions of the IE gene product. These experiments demonstrated that (i) the EHV-1 IE gene product is a bifunctional protein capable of both positive and negative modulation of gene expression; (ii) the iE gene product possesses an autoregulatory function which represses the IE promoter; (iii) IE autoregulation is dependent on IF promoter sequences mapping within positions -288 to +73 relative to the transcription initiation site (+ 1) of the IE gene; (iv) the IE gene product can independently activate the EHV-1 tk promoter (an early promoter) by as much as 60-fold, (v) two EHV-1 beta-gamma (leaky late) promoters, those of IR5 (gene 5 in the inverted repeat) and the glycoprotein D gene, demonstrate a requirement for both the IE gene product as well as a gene product encoded within the EHV-1 XbaI G fragment for significant activation; and (vi) the IE gene product is capable of activating heterologous viral promoters