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Holden VR, Yalamanchili RR, Harty RN, O'Callaghan DJ. Identification and characterization of an equine herpesvirus 1 late gene encoding a potential zinc finger. Virology 1992; 188:704-13. [PMID: 1316680 DOI: 10.1016/0042-6822(92)90525-t] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In this report, we present the DNA sequence and transcriptional characterization of a gene (IR5) that maps within each of the inverted repeat (IR) segments of the equine herpesvirus type 1 (EHV-1) genome. The IR5 open reading frame (ORF) is located within both IR sequences (nucleotides 9932-10,642 of the IR). DNA sequence analyses of the IR5 gene region revealed an ORF of 236 amino acids (24,793 Da) that showed significant homology to ORF64 of varicella-zoster virus and ORF3 of EHV-4 both of which map within the inverted repeats and to the US10 ORF of herpes simplex virus type 1 (HSV-1) which maps within the unique short segment. Additional analyses of the nucleotide sequence failed to reveal any overlapping ORFs that would correspond to US11 or US12 of HSV-1. Interestingly, the IR5 ORF of EHV-1 possesses a sequence of 13 amino acids (CAYWCCLGHAFAC) that is a perfect match to the consensus zinc finger motif (C-X2-4-C-X2-15-C/H-X2-4-C/H). Putative cis-acting elements flanking the IR5 ORF include a TATA box (nucleotides 9864-9870), a CAAT box (nucleotides 9709-9714), and a polyadenylation signal (nucleotides 10,645-10,650). Northern blot and S1 nuclease analyses identified a single 0.9-kb mRNA species that first appears at 2 hr postinfection, and whose synthesis is reduced in the presence of phosphonoacetic acid, an inhibitor of EHV-1 DNA synthesis. Thus, the IR5 gene of EHV-1 exhibits characteristics representative of a late gene of the gamma-1 class. The characterization of the IR5 gene at the DNA and RNA levels will facilitate ongoing studies to identify and characterize the IR5 polypeptide.
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Affiliation(s)
- V R Holden
- Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport 71130-3932
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Holden VR, Yalamanchili RR, Harty RN, O'Callaghan DJ. ICP22 homolog of equine herpesvirus 1: expression from early and late promoters. J Virol 1992; 66:664-73. [PMID: 1370553 PMCID: PMC240765 DOI: 10.1128/jvi.66.2.664-673.1992] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The complete nucleotide sequence of the short region, made up of a unique segment (Us; 6.5 kb) bracketed by a pair of inverted repeat sequences (IR; 12.8 kb each), of the equine herpesvirus 1 (EHV-1) genome has been determined recently in our laboratory. Analysis of the IR segment revealed a major open reading frame (ORF) designated IR4. The IR4 ORF exhibits significant homology to the immediate-early gene US1 (ICP22) of herpes simplex virus type 1 and to the ICP22 homologs of varicella-zoster virus (ORF63), pseudorabies virus (RSp40), and equine herpesvirus 4 (ORF4). The IR4 ORF is located entirely within each of the inverted repeat sequences (nucleotides [nt] 7918 to 9327) and has the potential to encode a polypeptide of 469 amino acids (49,890 Da). Within the IR4 ORF are two reiterated sequences: a 7-nt sequence tandemly repeated 17 times and a 25-nt sequence tandemly repeated 13 times. Nucleotide sequence analyses of IR4 also revealed several potential cis-regulatory sequences, two TATA sequences separated by 287 nt, an in-frame translation initiation codon following each TATA sequence, and a single polyadenylation site. To address the nature of the mRNA species encoded by IR4, we used Northern (RNA) blot and S1 nuclease analyses. RNA mapping data revealed that IR4 has two promoters that are regulated differentially during a lytic infection. A 1.4-kb mRNA appears initially at 2 h postinfection and is an early transcript since its synthesis is not affected by the presence of phosphonoacetic acid, an inhibitor of EHV-1 DNA replication. In contrast, a 1.7-kb mRNA appears at later times postinfection and is designated as a gamma-1 transcript, since its synthesis is significantly reduced by phosphonoacetic acid. These IR4-specific mRNAs are 3' coterminal, have unique 5' termini, and would code for in-frame, overlapping, carboxy-coterminal proteins of 293 and 469 amino acids, respectively. Interestingly, the site of homologous recombination to generate the genome of EHV-1 defective interfering particles that initiate persistent infection occurs between nt 3244 and 3251 of UL3 (ICP27 homolog) and nt 9027 and 9034 of IR4 (ICP22 homolog). Thus, this recombination event would generate a unique ORF that would encode a potential protein whose amino end was derived from the N-terminal 193 amino acids of the ICP22 homolog and whose carboxyl end was derived from the C-terminal 68 amino acids of the ICP27 homolog.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Blotting, Northern
- Cloning, Molecular
- DNA Replication
- Genome, Viral
- Herpesvirus 1, Equid/genetics
- Herpesvirus 1, Suid/genetics
- Herpesvirus 3, Human/genetics
- Immediate-Early Proteins
- L Cells
- Mice
- Molecular Sequence Data
- Open Reading Frames
- Poly A/genetics
- Poly A/isolation & purification
- Promoter Regions, Genetic
- RNA/genetics
- RNA/isolation & purification
- RNA, Messenger
- Repetitive Sequences, Nucleic Acid
- Restriction Mapping
- Sequence Homology, Nucleic Acid
- Simplexvirus/genetics
- Viral Proteins/genetics
- Viral Regulatory and Accessory Proteins
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Affiliation(s)
- V R Holden
- Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport 71130-3932
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Smith RH, Caughman GB, O'Callaghan DJ. Characterization of the regulatory functions of the equine herpesvirus 1 immediate-early gene product. J Virol 1992; 66:936-45. [PMID: 1309921 PMCID: PMC240795 DOI: 10.1128/jvi.66.2.936-945.1992] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
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.
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Affiliation(s)
- R H Smith
- Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport 71130-3932
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Harty RN, Yalamanchili RR, O'Callaghan DJ. Transcriptional analysis of the UL1 gene of equine herpesvirus 1: a gene conserved in the genome of defective interfering particles. Virology 1991; 183:830-3. [PMID: 1649513 DOI: 10.1016/0042-6822(91)91020-h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Defective interfering particles (DIPs) of equine herpesvirus type 1 (EHV-1) are biologically active, in that they mediate the coestablishment of oncogenic transformation and persistent infection in permissive, primary hamster embryo fibroblasts. The DIP genome is composed of EHV-1 sequences originating from the L-terminus (mapping units (m.u.) 0.00-0.023), the junction of the unique long (UL) region and the internal inverted repeat (IR) (m.u. 0.78-0.79 and 0.99-1.00), and the central portion of the IR (m. u. 0.83-0.87 and 0.91-0.95). The nature of one of the genes (UL1) mapping at the L-terminus was analyzed at the RNA level by Northern blot hybridization and S1 nuclease analyses. These data, and DNA sequencing analyses reported previously revealed that the UL1 gene: (1) contains a major open reading frame (ORF) of 258 amino acids, (2) is a homologue of the ORF2 gene of varicella zoster virus (VZV), (3) is conserved in the genome of DIPs of EHV-1, (4) encodes a 1.2-kb early (E) mRNA that is transcribed toward the short region of the genome, (5) utilizes a transcription initiation site approximately 1,120 nucleotides from the L-terminus, and (6) utilizes a transcription termination site approximately 2211 nucleotides from the L-terminus. These initial studies serve as the basis of future work to determine the function of the UL1 gene in cytolytic infection, and its potential role in EHV-1 persistent infection.
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Affiliation(s)
- R N Harty
- Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport 71130-3932
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Harty RN, O'Callaghan DJ. An early gene maps within and is 3' coterminal with the immediate-early gene of equine herpesvirus 1. J Virol 1991; 65:3829-38. [PMID: 1645793 PMCID: PMC241414 DOI: 10.1128/jvi.65.7.3829-3838.1991] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The immediate-early (IE) gene (IR1 gene) of equine herpesvirus 1 (EHV-1) encodes a single, spliced 6.0-kb mRNA during cytolytic infection. However, under early (in the presence of phosphonoacetic acid) and late (8 h postinfection; no metabolic inhibitors) conditions, in addition to the 6.0-kb IE mRNA, a 4.4-kb early (E) mRNA is transcribed from the IE gene region beginning at approximately 4 h postinfection. To map and characterize the 4.4-kb E mRNA and the protein product of this early gene (IR2 gene), Northern (RNA) blot hybridization, S1 nuclease, primer extension, and in vitro transcription and translation analyses were used. The data from RNA mapping analyses revealed that the 4.4-kb E IR2 mRNA (i) maps at nucleotides 4481 to 635 within each of the inverted repeats of the short region and thus is encoded by sequences that lie entirely within the IE gene, (ii) is transcribed in the same direction as the IE mRNA, initiating at nucleotide 4481, which lies 25 bp downstream of a putative TATA-like sequence and 1,548 bp downstream of the transcription initiation site of the IE mRNA, and (iii) is 3' coterminal with the IE mRNA which terminates at nucleotide 635 of the inverted repeats. The IR2 open reading frame was inserted into the transcription expression vector pGEM-3Z, and the RNA transcribed from this construct (pGEM44) was shown to be a 4.2-kb transcript that contained all IR2 sequences. In vitro translation of the 4.2-kb RNA yielded a major protein of approximately 130 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. This protein corresponds to the predicted IR2 product of 1,165 amino acids that would be in frame with the major IE polypeptide (IE1 = 200 kDa; 1,487 amino acids) and thus would be a 5'-truncated form of the IE1 polypeptide. The presence and potential role of the IR2 gene embedded within the IR1 gene increase the complexity of the regulation of the IE gene region during various stages of a productive infection.
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Affiliation(s)
- R N Harty
- Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport 71130-3932
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Harty RN, Colle CF, Grundy FJ, O'Callaghan DJ. Mapping the termini and intron of the spliced immediate-early transcript of equine herpesvirus 1. J Virol 1989; 63:5101-10. [PMID: 2555546 PMCID: PMC251172 DOI: 10.1128/jvi.63.12.5101-5110.1989] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Equine herpesvirus 1 (EHV-1) has been shown to synthesize a 6.0-kilobase (kb) species of immediate-early (IE) mRNA in productively infected cells. This IE gene region maps within the outer portion (map units 0.79 to 0.83 and 0.96 to 1.00) of the two inverted repeat segments of the short genomic region, and elucidation of its DNA sequence has revealed multiple potential open reading frames (ORFs), including a major ORF of 4,461 nucleotides (F. J. Grundy, R. P. Baumann, and D. J. O'Callaghan, Virology 172:223-236, 1989). Analyses of IE polypeptides synthesized in EHV-1-infected cells (in vivo) and in vitro translation of hybrid-selected IE mRNA indicated that multiple species of IE proteins are encoded by this IE mRNA species. To address the nature of the 6.0-kb IE RNA species, Northern (RNA) blot hybridization, S1 nuclease mapping, and primer extension analyses have been employed. These data revealed that no major introns were detected within the body of the IE transcript. However, the IE mRNA was shown to be spliced at the 5' terminus, such that a 372-base intron containing two small ORFs (19 and 51 amino acids) was removed from the leader region of the transcript. This splicing event reduced the leader region from 625 to 253 bases. S1 and primer extension analyses of the 5' terminus of this transcript revealed that the transcription initiation site is located 24 to 26 bases downstream of the consensus TATAAA motif. The 3' transcription termination site was mapped by S1 nuclease analysis to approximately 10 to 20 bases downstream of the polyadenylation signal, AATAAA. The distance from the stop codon of the major ORF to the polyadenylation site is approximately 300 bases. Results from S1 nuclease experiments indicated that splicing does not occur at the 3' terminus. These studies indicated that the EHV-1 6.0-kb IE mRNA is spliced at the 5' terminus and that alternative splicing of this transcript may function in regulating translation of the IE mRNA species.
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MESH Headings
- Animals
- Base Sequence
- Blotting, Northern
- Cell Line
- Cloning, Molecular
- DNA, Viral/genetics
- Genes, Regulator
- Genes, Viral
- Herpesviridae/genetics
- Herpesvirus 1, Equid/genetics
- Introns
- Molecular Sequence Data
- RNA Splicing
- RNA, Messenger/genetics
- RNA, Viral/genetics
- RNA, Viral/isolation & purification
- Restriction Mapping
- Terminator Regions, Genetic
- Transcription, Genetic
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Affiliation(s)
- R N Harty
- Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport 71130-3932
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Gray WL, Baumann RP, Robertson AT, Caughman GB, O'Callaghan DJ, Staczek J. Regulation of equine herpesvirus type 1 gene expression: characterization of immediate early, early, and late transcription. Virology 1987; 158:79-87. [PMID: 3033896 DOI: 10.1016/0042-6822(87)90240-6] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The regulation of equine herpesvirus type 1 (EHV-1) transcription was examined in infected rabbit kidney cells using metabolic inhibitors. In order to map EHV-1 immediate early, early, and late transcripts, viral RNA was 32P-labeled in vivo and hybridized to EHV-1 DNA restriction fragments immobilized on nitrocellulose filters. Immediate early viral RNA was mapped to one region of the viral genome within the inverted repeat DNA sequences (map units 0.78-0.83 and 0.95-1.0). Northern blot hybridization analysis using a 32P-labeled cloned DNA probe from this region identified a single immediate early viral transcript (approximately 6 kb). Transcription of early and late genes was not restricted to any specific region on the viral genome as indicated by the ability of 32P-labeled early and late RNA to hybridize to EHV-1 restriction endonuclease fragments from both the long and short components of EHV-1 DNA. Additional experiments performed without the use of metabolic inhibitors confirmed that EHV-1 transcription is temporally regulated. The characterization of EHV-1 transcription during productive infection will serve as a reference for the analysis of viral transcripts in oncogenically transformed and persistently infected cells.
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Caughman GB, Staczek J, O'Callaghan DJ. Equine herpesvirus type 1 infected cell polypeptides: evidence for immediate early/early/late regulation of viral gene expression. Virology 1985; 145:49-61. [PMID: 2990102 DOI: 10.1016/0042-6822(85)90200-4] [Citation(s) in RCA: 76] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
EHV-1 polypeptide synthesis was examined in productively infected rabbit kidney and hamster embryo cells. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses of extracts from [35S]methionine- and 3H-amino acid-labeled-infected and mock-infected cultures revealed the presence of 30 infected cell-specific polypeptides (ICPs) which ranged in apparent molecular weights from 16.5K to 213K. Twenty-two of these ICPs comigrated with virion structural proteins. Four ICPs (203K, 176K, 151K, 129K) were detected in extracts of infected cultures labeled in the presence or absence of actinomycin D (Act D) immediately after release from a 4-hr treatment with cycloheximide (CH). These polypeptides, which were designated as EHV-1 immediate early (alpha) ICPs, were not detected in unblocked (non-CH-treated) infected cells. The most abundant ICP was a 31.5K nonstructural protein which, in addition to a 74K protein, was detected in unblocked infected cells at 2-3 hr postinfection. These proteins appeared to be regulated as early (beta) ICPs, since neither protein was observed in Act D-treated cultures released from CH block. Twelve ICPs were classified as late (gamma) polypeptides on the basis of their reduced synthesis in cultures in which viral DNA replication was inhibited by phosphonoacetic acid. All but one (40K) of these late ICPs corresponded to virion structural proteins.
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Henry BE, Robinson RA, Dauenhauer SA, Atherton SS, Hayward GS, O'Callaghan DJ. Structure of the genome of equine herpesvirus type 1. Virology 1981; 115:97-114. [PMID: 6270904 DOI: 10.1016/0042-6822(81)90092-1] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Krell PJ, Stoltz DB. Unusual Baculovirus of the Parasitoid Wasp
Apanteles melanoscelus
: Isolation and Preliminary Characterization. J Virol 1979; 29:1118-30. [PMID: 16789176 PMCID: PMC353272 DOI: 10.1128/jvi.29.3.1118-1130.1979] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A baculovirus present in the female reproductive tract of the parasitoid wasp
Apanteles melanoscelus
has been isolated and partially characterized. Viral DNA is double stranded, circular, and of highly variable molecular weight ranging from 2 × 10
6
to 25 × 10
6
; the DNA is of homogeneous density at ρ = 1.694 g/ml. Acrylamide gels resolve 18 polypeptide bands in the case of purified virions; four to five of these appear in a semipurified nucleocapsid preparation. The electrophoretic profiles obtained are compared with those of two other baculoviruses.
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Affiliation(s)
- P J Krell
- Department of Microbiology, Dalhousie University, Halifax, Nova Scotia, Canada
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Henry BE, Newcomb WW, O'Callaghan DJ. Biological and biochemical properties of defective interfering particles of equine herpesvirus type 1. Virology 1979; 92:495-506. [PMID: 218357 DOI: 10.1016/0042-6822(79)90152-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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