The equine herpesvirus 1 (EHV-1) UL3 gene, an ICP27 homolog, is necessary for full activation of gene expression directed by an EHV-1 late promoter.
We have previously reported that the equine herpesvirus 1 (EHV-1) XbaI G restriction fragment (nucleotides 1436 to 7943 relative to the left terminus of the EHV-1 genome [Kentucky A strain]) is required in combination with the EHV-1 immediate-early (IE) gene to achieve significant activation of two representative EHV-1 late promoter-chloramphenicol acetyltransferase (CAT) recombinants in transient expression assays. In this report, we demonstrate that the XbaI G-encoded UL3 gene (an ICP27 homolog) provides a trans-acting factor which acts (in combination with the EHV-1 IE gene product) to increase reporter gene expression directed by an EHV-1 late promoter-CAT recombinant plasmid. We show that cloned copies of UL3 can successfully substitute for the XbaI G fragment in CAT assays and that stop codon insertion within the UL3 open reading frame inhibits the ability of UL3 to activate reporter gene expression in trans.
Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport 71130-3932.
R H
RH
Smith
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Y
Zhao
D J
DJ
O'Callaghan
D003062:Codon / Q000235:genetics; D015967:Gene Expression Regulation, Viral; D005814:Genes, Viral / Q000235:genetics*; D004861:Herpesvirus 1, Equid / Q000235:genetics*; D017874:Immediate-Early Proteins; D011401:Promoter Regions, Genetic / Q000235:genetics*; D016364:Reading Frames / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics*; D015533:Transcriptional Activation / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics*
D003062:Codon; C057120:ICP27 protein, human herpesvirus 1; D017874:Immediate-Early Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D014764:Viral Proteins