Characterization of the regulatory functions of the equine herpesvirus 1 immediate-early gene product.
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 158:79-87, 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 IE 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.
Smith
R H
RH
Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport 71130-3932.
Caughman
G B
GB
O'Callaghan
D J
DJ
D000818:Animals; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D015967:Gene Expression Regulation, Viral; D005814:Genes, Viral; D005822:Genetic Vectors; D004861:Herpesvirus 1, Equid / Q000235:genetics*; D007739:L Cells; D051379:Mice; D010957:Plasmids; D011401:Promoter Regions, Genetic; D015183:Restriction Mapping; D015534:Trans-Activators / Q000235:genetics*; D014162:Transfection; D014764:Viral Proteins / Q000235:genetics
D015534:Trans-Activators; D014764:Viral Proteins; D015500:Chloramphenicol O-Acetyltransferase