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Bhave S, Elford H, McVoy MA. Ribonucleotide reductase inhibitors hydroxyurea, didox, and trimidox inhibit human cytomegalovirus replication in vitro and synergize with ganciclovir. Antiviral Res 2013; 100:151-8. [PMID: 23933116 DOI: 10.1016/j.antiviral.2013.07.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 07/15/2013] [Accepted: 07/24/2013] [Indexed: 01/12/2023]
Abstract
Ganciclovir (GCV) is a deoxyguanosine analog that is effective in inhibiting human cytomegalovirus (HCMV) replication. In infected cells GCV is converted to GCV-triphosphate which competes with dGTP for incorporation into the growing DNA strand by the viral DNA polymerase. Incorporated GCV promotes chain termination as it is an inefficient substrate for elongation. Because viral DNA synthesis also relies on cellular ribonucleotide reductase (RR) to synthesize deoxynucleotides, RR inhibitors are predicted to inhibit HCMV replication. Moreover, as dGTP competes with GCV-triphosphate for incorporation, RR inhibitors may also synergize with GCV by reducing intracellular dGTP levels and there by promoting increased GCV-triphosphate utilization by DNA polymerase. To investigate potential of RR inhibitors as anti-HCMV agents both alone and in combination with GCV, HCMV-inhibitory activities of three RR inhibitors, hydroxyurea, didox, and trimidox, were determined. In both spread inhibition and yield reduction assays RR inhibitors had modest anti-HCMV activity with 50% inhibitory concentrations ranging from 36±1.7 to 221±52μM. However, all three showed significant synergy with GCV at concentrations below their 50% inhibitory and 50% toxic concentrations. These results suggest that combining GCV with relatively low doses of RR inhibitors could significantly potentiate the anti-HCMV activity of GCV in vivo and could improve clinical response to therapy.
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Affiliation(s)
- Sukhada Bhave
- Department of Pediatrics, Virginia Commonwealth University School of Medicine, Richmond, VA 23298, USA
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2
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Mercorelli B, Sinigalia E, Loregian A, Palù G. Human cytomegalovirus DNA replication: antiviral targets and drugs. Rev Med Virol 2008; 18:177-210. [PMID: 18027349 DOI: 10.1002/rmv.558] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Human cytomegalovirus (HCMV) infection is associated with severe morbidity and mortality in immunocompromised individuals, in particular transplant recipients and AIDS patients, and is the most frequent congenital viral infection in humans. There are currently five drugs approved for HCMV treatment: ganciclovir and its prodrug valganciclovir, foscarnet, cidofovir and fomivirsen. These drugs have provided a major advance in HCMV disease management, but they suffer from poor bioavailability, significant toxicity and limited effectiveness, mainly due to the development of drug resistance. Fortunately, there are several novel and potentially very effective new compounds which are under pre-clinical and clinical evaluation and may address these limitations. This review focuses on HCMV proteins that are directly or indirectly involved in viral DNA replication and represent already established or potential novel antiviral targets, and describes both currently available drugs and new compounds against such protein targets.
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Affiliation(s)
- Beatrice Mercorelli
- Department of Histology, Microbiology and Medical Biotechnologies, University of Padua, 35121 Padua, Italy
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3
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Hertel L, Mocarski ES. Global analysis of host cell gene expression late during cytomegalovirus infection reveals extensive dysregulation of cell cycle gene expression and induction of Pseudomitosis independent of US28 function. J Virol 2004; 78:11988-2011. [PMID: 15479839 PMCID: PMC523267 DOI: 10.1128/jvi.78.21.11988-12011.2004] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Replication of human cytomegalovirus (CMV) depends on host cell gene products working in conjunction with viral functions and leads to a dramatic dysregulation of cell cycle gene expression. Comprehensive transcriptional profiling was used to identify pathways most dramatically modulated by CMV at late times during infection and to determine the extent to which expression of the viral chemokine receptor US28 contributed to modulating cellular gene expression. Cells infected with the AD169 strain of virus or a fully replication competent US28-deficient derivative (RV101) were profiled throughout the late phase of infection (50, 72, and 98 h postinfection). Although sensitive statistical analysis showed striking global changes in transcript levels in infected cells compared to uninfected cells, the expression of US28 did not contribute to these alterations. CMV infection resulted in lower levels of transcripts encoding cytoskeletal, extracellular matrix, and adhesion proteins, together with small GTPases and apoptosis regulators, and in higher levels of transcripts encoding cell cycle, DNA replication, energy production, and inflammation-related gene products. Surprisingly, a large number of cellular transcripts encoding mitosis-related proteins were upmodulated at late times in infection, and these were associated with the formation of abnormal mitotic spindles and the appearance of pseudomitotic cells. These data extend our understanding of how broadly CMV alters the regulation of host cell cycle gene products and highlight the establishment of a mitosis-like environment in the absence of cellular DNA replication as important for viral replication and maturation.
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Affiliation(s)
- Laura Hertel
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305-5124, USA
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4
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Sanchez V, McElroy AK, Yen J, Tamrakar S, Clark CL, Schwartz RA, Spector DH. Cyclin-dependent kinase activity is required at early times for accurate processing and accumulation of the human cytomegalovirus UL122-123 and UL37 immediate-early transcripts and at later times for virus production. J Virol 2004; 78:11219-32. [PMID: 15452241 PMCID: PMC521808 DOI: 10.1128/jvi.78.20.11219-11232.2004] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Human cytomegalovirus (HCMV) infection leads to dysregulation of multiple cell cycle-regulatory proteins. In this study, we examined the effects of inhibition of cyclin-dependent kinase (cdk) activity on viral replication. With the drug Roscovitine, a specific inhibitor of cyclin-dependent kinases 1, 2, 5, 7, and 9, we have shown that during the first 6 h of infection, cyclin-dependent kinase-dependent events occurred that included the regulated processing and accumulation of the immediate-early (IE) UL122-123 transcripts and UL36-37 transcripts. Altered processing of UL122-123 led to a loss of IE1-72 and an increase in IE2-86. The ratio of spliced to unspliced UL37 transcripts also changed. These effects did not require de novo protein synthesis or degradation of proteins by the proteasome. Addition of Roscovitine at the beginning of the infection was also associated with inhibition of expression of selected viral early gene products, viral DNA replication, and late viral gene expression. When Roscovitine was added after the first 6 h of infection, the effects on IE gene expression were no longer observed and viral replication proceeded through the late phase, but viral titers were reduced. The reduction in viral titer was observed even when Roscovitine was first added at 48 h postinfection, indicating that cyclin-dependent kinase activity is required at both IE and late times. Flavopiridol, another specific inhibitor of cyclin-dependent kinases, had similar effects on IE and early gene expression. These results underscore the importance of accurate RNA processing and reiterate the significant role of cell cycle-regulatory factors in HCMV infection.
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Affiliation(s)
- Veronica Sanchez
- Molecular Biology Section, Mail Code 0366, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0366, USA
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5
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Kiehl A, Huang L, Franchi D, Anders DG. Multiple 5′ ends of human cytomegalovirus UL57 transcripts identify a complex, cycloheximide-resistant promoter region that activates oriLyt. Virology 2003; 314:410-22. [PMID: 14517093 DOI: 10.1016/s0042-6822(03)00438-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The human cytomegalovirus (HCMV) UL57 gene lies adjacent to HCMV oriLyt, from which it is separated by an organizationally conserved, mostly noncoding region that is thought to both regulate UL57 expression and activate oriLyt function. However, the UL57 promoter has not been studied. We determined the 5' ends of UL57 transcripts toward an understanding of the potential relationship between UL57 expression and oriLyt activation. The results presented here identified three distinct 5' ends spread over 800 bp, at nt 90302, 90530, and 91138; use of these sites exhibited differential sensitivity to phosphonoformic acid treatment. Interestingly, a 10-kb UL57 transcript accumulated in cycloheximide-treated infected cells, even though other early transcripts were not detectable. However, the 10-kb transcript did not accumulate in cells treated with the more stringent translation inhibitor anisomycin. Consistent with the notion that the identified 5' ends arise from distinct transcription start sites, the sequences upstream of sites I and II functioned as promoters responsive to HCMV infection in transient assays. However, the origin-proximal promoter region III required downstream sequences for transcriptional activity. Mutation of candidate core promoter elements suggested that promoter III is regulated by an initiator region (Inr) and a downstream promoter element. Finally, a 42-bp sequence containing the candidate Inr activated a minimal oriLyt core construct in transient replication assays. Thus, these studies showed that a large, complex promoter region with novel features controls UL57 expression, and identified a sequence that regulates both UL57 transcription and oriLyt activation.
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Affiliation(s)
- Anita Kiehl
- The David Axelrod Institute, Wadsworth Center, NYSDOH, P.O. Box 22002, Albany, NY 12201-2002, USA
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6
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Hwang ES, Kim J, Jong HS, Park JW, Park CG, Cha CY. Characteristics of DNA-binding activity of human cytomegalovirus ppUL44. Microbiol Immunol 2001; 44:827-32. [PMID: 11128066 DOI: 10.1111/j.1348-0421.2000.tb02570.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Human cytomegalovirus (HCMV)-specific monoclonal antibody, SCMVM34, recognizes the early antigen encoded by UL44 of HCMV. This antigen is confined to the nucleus of HCMV-infected cells. This study was performed to characterize the DNA-binding activity of the protein encoded by UL44 of HCMV. The nuclear and cytoskeletal fraction of HCMV-infected cells was subjected to 0.4 M NaCl extraction, DEAE-Sephacel ion exchange chromatography, DNA-cellulose chromatography and SDS-PAGE analysis with monitoring of the reactive protein using SCMVM34 monoclonal antibody. The molecular weights of the resultant proteins were found to be 34, 40 and 52 kDa. The internal peptide fragments were isolated by tryptic digestion and reverse-phase HPLC. The internal amino acid sequence analysis of the peptides from the HPLC profile revealed that the antigen recognized by SCMVM34 monoclonal antibody was ppUL44. The reactive antigen began to be eluted from 250 mM NaCl (Tris-HCl pH 7.4) in DNA cellulose. The 34 kDa protein seems to bind to DEAE more tightly than the 52 kDa protein. The surface charge of 34 kDa might be more basic. Conclusively, the antigen recognized by SCMVM34 was the protein encoded by HCMV UL44, which was localized in the nuclei after HCMV infection, and was the DNA-binding protein with the characteristic that the surface charge of the molecule was more basic, as the molecular weights of the protein were decreased.
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Affiliation(s)
- E S Hwang
- Department of Microbiology, Seoul National University College of Medicine, and Institute of Endemic Diseases, Republic of Korea.
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7
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McCue LA, Anders DG. Soluble expression and complex formation of proteins required for HCMV DNA replication using the SFV expression system. Protein Expr Purif 1998; 13:301-12. [PMID: 9693054 DOI: 10.1006/prep.1998.0916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Several of the viral proteins required for human cytomegalovirus (HCMV) DNA replication have been difficult to study due to their low abundance in infected cells and low solubility in bacterial or insect-cell expression systems. Therefore we used the Semliki Forest virus expression system to express these proteins in mammalian cells. All of the recombinant proteins were soluble, on the basis of ultracentrifugation properties and their ability to be immunoprecipitated from solution with specific antibodies. Pulse-chase analysis of the 86-kDa major immediate-early protein (IE86) revealed two expressed forms-a precursor and a product-indicating that this recombinant protein, like the native HCMV protein, is posttranslationally processed. The recombinant proteins (polymerase core and accessory as well as the IE86 and pUL84) formed stable complexes similar to those known to form in HCMV-infected cells. The recombinant DNA polymerase holoenzyme also exhibited enzyme activity that was phosphonoformic acid sensitive, as is the infected-cell DNA polymerase activity. This expression system offers many advantages for the expression and study of the HCMV replication proteins, including the expression of soluble, active proteins that are able to interact to form complexes. Additionally, the relative ease with which SFV recombinants can be made lends itself to the construction and evaluation of mutants.
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Affiliation(s)
- L A McCue
- Wadsworth Center, University at Albany School of Public Health, Albany, New York, 12201-2002, USA
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8
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Abstract
Cell cycle progression during cytomegalovirus infection was investigated by fluorescence-activated cell sorter (FACS) analysis of the DNA content in growth-arrested as well as serum-stimulated human fibroblasts. Virus-infected cells maintained in either low (0.2%) or high (10%) serum failed to progress into S phase and failed to divide. DNA content analysis in the presence of G1/S (hydroxyurea and mimosine) and G2/M (nocodazole and colcemid) inhibitors demonstrated that upon virus infection of quiescent (G0) cells, the cell cycle did not progress beyond the G1/S border even after serum stimulation. Proteins which normally indicate G1/S transition (proliferating cell nuclear antigen [PCNA]) or G2/M transition (cyclin B1) were elevated by virus infection. PCNA levels were induced in infected cells and exhibited a punctate pattern of nuclear staining instead of the diffuse pattern observed in mock-infected cells. Cyclin B1 was induced in infected cells which exhibited a G1/S DNA content by FACS analysis, suggesting that expression of this key cell cycle function was dramatically altered by viral functions. These data demonstrate that contrary to expectations, cytomegalovirus inhibits normal cell cycle progression. The host cell is blocked prior to S phase to provide a favorable environment for viral replication.
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Affiliation(s)
- D Dittmer
- Department of Microbiology and Immunology, Stanford University School of Medicine, California 94305-5402, USA
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9
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Heilbronn R, Albrecht I, Stephan S, Bürkle A, zur Hausen H. Human cytomegalovirus induces JC virus DNA replication in human fibroblasts. Proc Natl Acad Sci U S A 1993; 90:11406-10. [PMID: 8248262 PMCID: PMC47991 DOI: 10.1073/pnas.90.23.11406] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
JC virus, a human papovavirus, is the causative agent of the demyelinating brain disease progressive multifocal leucoencephalopathy (PML). PML is a rare but fatal disease which develops as a complication of severe immunosuppression. Latent JC virus is harbored by many asymptomatic carriers and is transiently reactivated from the latent state upon immunosuppression. JC virus has a very restricted host range, with human glial cells being the only tissue in which it can replicate at reasonable efficiency. Evidence that latent human cytomegalovirus is harbored in the kidney similar to latent JC virus led to the speculation that during episodes of impaired immunocompetence, cytomegalovirus might serve as helper virus for JC virus replication in otherwise nonpermissive cells. We show here that cytomegalovirus infection indeed leads to considerable JC virus DNA replication in cultured human fibroblasts that are nonpermissive for the replication of JC virus alone. Cytomegalovirus-mediated JC virus replication is dependent on the JC virus origin of replication and T antigen. Ganciclovir-induced inhibition of cytomegalovirus replication is associated with a concomitant inhibition of JC virus replication. These results suggest that reactivation of cytomegalovirus during episodes of immunosuppression might lead to activation of latent JC virus, which would enhance the probability of subsequent PML development. Ganciclovir-induced repression of both cytomegalovirus and JC virus replication may form the rational basis for the development of an approach toward treatment or prevention of PML.
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Affiliation(s)
- R Heilbronn
- Deutsches Krebsforschungszentrum, Heidelberg, Germany
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10
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Pari GS, Anders DG. Eleven loci encoding trans-acting factors are required for transient complementation of human cytomegalovirus oriLyt-dependent DNA replication. J Virol 1993; 67:6979-88. [PMID: 8230421 PMCID: PMC238157 DOI: 10.1128/jvi.67.12.6979-6988.1993] [Citation(s) in RCA: 212] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Recently we described the use of human cytomegalovirus (HCMV) cosmid clones in a cotransfection assay of HCMV oriLyt replication (G. S. Pari, M. A. Kacica, and D. G. Anders, J. Virol. 67:2575-2582, 1993). We have now used this assay to identify 11 distinct required loci encoding trans-acting factors sufficient for transient complementation of oriLyt-dependent DNA replication. This set includes all of the virus genes essential to initiate and perform DNA synthesis together with the virus genes required to express these replication functions from their native promoters. Six of the identified loci span open reading frames (ORFs) that encode homologs or probable homologs of herpes simplex virus type 1 replication genes, consistent with predictions based on sequence similarities and biochemical properties. These include the DNA polymerase UL54 and polymerase-associated protein UL44, the single-stranded-DNA-binding protein UL57, and proposed subunits of a helicase-primase complex, UL70, UL105, and UL101-102. Frameshift mutations in any one of these essential ORFs abrogated complementation of DNA replication. Three required loci, UL36-38, IRS1 (or TRS1), and IE1/IE2, encode known regulatory proteins. The remaining two loci span ORFs UL84 and UL112-113 and encode early temporal class nucleus-associated proteins of unknown function. Neither of these genes have been implicated previously in DNA replication or in regulating gene expression, nor have counterparts in herpes simplex virus type 1 or Epstein-Barr virus been described. The results presented here will facilitate investigation of the mechanisms and regulation of HCMV lytic-phase DNA replication.
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Affiliation(s)
- G S Pari
- Laboratory of Virology, Wadsworth Center for Laboratories and Research, Albany, New York
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11
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Pari GS, Kacica MA, Anders DG. Open reading frames UL44, IRS1/TRS1, and UL36-38 are required for transient complementation of human cytomegalovirus oriLyt-dependent DNA synthesis. J Virol 1993; 67:2575-82. [PMID: 8386266 PMCID: PMC237578 DOI: 10.1128/jvi.67.5.2575-2582.1993] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Previous results showed that plasmids containing human cytomegalovirus (HCMV) oriLyt are replicated after transfection into permissive cells if essential trans-acting factors are supplied by HCMV infection (D. G. Anders, M. A. Kacica, G. S. Pari, and S. M. Punturieri, J. Virol. 66:3373-3384, 1992). We have now used oriLyt as a reporter of HCMV DNA replication in a transient complementation assay in which cotransfected cosmid clones, instead of HCMV infection, provided essential trans-acting factors. Complemented replication was oriLyt dependent and phosphonoformic acid sensitive and produced tandem arrays typical of HCMV lytic-phase DNA synthesis. Thus, this assay provides a valid genetic test to find previously unidentified genes that are essential for DNA synthesis and to corroborate functional predictions made by nucleotide sequence comparisons and biochemical analyses. Five cosmids were necessary and sufficient to produce origin-dependent DNA synthesis; all but one of these required cosmids contain at least one candidate homolog of herpes simplex virus type 1 replication genes. We further used the assay to define essential regions in two of the required cosmids, pCM1017 and pCM1052. Results presented show that UL44, proposed on the basis of biochemical evidence to be the HCMV DNA polymerase accessory protein, was required for complementation. In addition, three genomic regions encoding regulatory proteins also were needed to produce origin-dependent DNA synthesis in this assay: (i) IRS1/TRS1, which cooperates with the major immediate-early proteins to activate UL44 expression; (ii) UL36-38; and (iii) the major immediate-early region comprising IE1 and IE2. Combined, these results unequivocally establish the utility of this approach for mapping HCMV replication genes. Thus, it will now be possible to define the set of HCMV genes necessary and sufficient for initiating and performing lytic-phase DNA synthesis as well as to identify those virus genes needed for their expression in human fibroblasts.
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Affiliation(s)
- G S Pari
- Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany
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12
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Messerle M, Keil GM, Schneider K, Koszinowski UH. Characterization of the murine cytomegalovirus genes encoding the major DNA binding protein and the ICP18.5 homolog. Virology 1992; 191:355-67. [PMID: 1329325 DOI: 10.1016/0042-6822(92)90198-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In several herpesviruses the genes for the major DNA binding protein (MDBP), a putative assembly protein, the glycoprotein B (gB), and the viral DNA polymerase (pol) collocate. In murine cytomegalovirus (MCMV), two members of this gene block, pol (Elliott, Clark, Jaquish, and Spector, 1991, Virology 185, 169-186) and gB (Rapp, Messerle, Bühler, Tannheimer, Keil, and Koszinowski, 1992, J. Virol., 66, 4399-4406) have been characterized. Here the two other MCMV genes are characterized, the gene encoding the MDBP and the ICP18.5 homolog encoding a putative assembly protein. Like in human cytomegalovirus (HCMV) the genes order is pol, gB, ICP18.5, and MDBP. The 4.2-kb MDBP mRNA is expressed first in the early phase, whereas the 3.0-kb ICP18.5 mRNA is a late transcript. The open reading frame of the MDBP gene has the capacity of encoding a protein of 1191 amino acids with a predicted molecular mass of 131.7 kDa. The MCMV ICP18.5 ORF is translated into a polypeptide of 798 amino acids with a calculated molecular mass of 89.1 kDa. Comparison of the amino acid sequences of the predicted proteins of MCMV with the respective proteins of HCMV, Epstein-Barr virus (EBV), and herpes simplex virus type-1 (HSV-1) reveals a striking homology ranging from 72% (HCMV), 50% (EBV), to 45% (HSV-1) for the MDBP sequence and from 74% (HCMV), 51% (EBV), to 49% (HSV-1) for the ICP18.5 sequence. These results establish the close relationship of the two cytomegaloviruses, and underline the usefulness of the murine model for studies on the biology of the CMV infection.
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Affiliation(s)
- M Messerle
- Department of Virology, University of Ulm, Germany
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13
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Welch AR, McNally LM, Gibson W. Cytomegalovirus assembly protein nested gene family: four 3'-coterminal transcripts encode four in-frame, overlapping proteins. J Virol 1991; 65:4091-100. [PMID: 1649317 PMCID: PMC248841 DOI: 10.1128/jvi.65.8.4091-4100.1991] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The genomic region encoding the assembly protein of simian cytomegalovirus (CMV) strain Colburn has been cloned, sequenced, and found to be organized as a nested set of four in-frame, 3'-coterminal genes, each with its own TATA promoter element and translational start codon, and all using a single 3' polyadenylation signal. The 3' end of the longest open reading frame (1.770 bp) was identical to the 930-bp sequence coding for the assembly protein precursor, as determined from a cDNA clone. The assembly protein coding region of human CMV strain AD169 was similarly organized, suggesting that both viral genomes could give rise to four independently transcribed 3'-coterminal RNAs coding for four overlapping, in-frame, carboxy-coterminal proteins. These predictions were tested and confirmed. Four mRNAs corresponding in size and sequence to those predicted were identified in both human and simian CMV-infected cells by using transcript-specific antisense oligonucleotide probes in Northern (RNA blot) assays. The 5' ends of the three largest of these Colburn transcripts were determined by S1 nuclease protection assays and found to map between the anticipated TATA sequences and corresponding translational start codons. The four predicted overlapping proteins were identified by immunoassays in lysates of simian and human CMV-infected cells by using an antiserum specific for the carboxyl end of the assembly protein precursor. The structural relationship of both sets of proteins was verified by comparing their peptide patterns following protein cleavage at tryptophan residues by N-chlorosuccinimide. The similar organization of the homologous coding regions in other herpesviruses into at least two nested, in-frame, 3'-coterminal genes is discussed.
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Affiliation(s)
- A R Welch
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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14
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Affiliation(s)
- L Rasmussen
- Division of Infectious Diseases, Stanford Medical School, California 94305
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15
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Spector DH, Klucher KM, Rabert DK, Wright DA. Human cytomegalovirus early gene expression. Curr Top Microbiol Immunol 1990; 154:21-45. [PMID: 2161321 DOI: 10.1007/978-3-642-74980-3_2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- D H Spector
- Department of Biology and Center for Molecular Genetics, University of California, San Diego, La Jolla 92093
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16
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Cockley KD, Rapp F. Analysis of viral proteins in human cytomegalovirus-infected cells during impaired lytic replication of herpes simplex virus. Virology 1989; 170:268-72. [PMID: 2541541 DOI: 10.1016/0042-6822(89)90376-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Herpes simplex virus (HSV) latency can be established in vitro following arrest of virus replication and survival of infected cells in culture. Human cytomegalovirus (HCMV) has been shown to interact with HSV, resulting in reactivation of latent HSV. In addition, impaired replication of superinfecting HSV occurs in HCMV-infected human cells. HCMV-infected human embryonic lung cells inhibit production of infectious HSV despite replication of HSV DNA at levels comparable to those in control cultures infected only with HSV. Using radioimmunoprecipitation techniques, we found that the synthesis of HSV type 1 proteins of the alpha, beta/gamma, and gamma kinetic classes was impaired during the restricted replication of HSV in HCMV-infected HEL cells. However, synthesis of the HSV beta protein ICP-8 and HCMV alpha and beta proteins was not significantly affected in superinfected cell cultures.
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Affiliation(s)
- K D Cockley
- Department of Microbiology and Immunology, Pennsylvania State University College of Medicine, Hershey 17033
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17
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Leach FS, Mocarski ES. Regulation of cytomegalovirus late-gene expression: differential use of three start sites in the transcriptional activation of ICP36 gene expression. J Virol 1989; 63:1783-91. [PMID: 2538657 PMCID: PMC248444 DOI: 10.1128/jvi.63.4.1783-1791.1989] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We have investigated the transcriptional regulation of the human cytomegalovirus gamma gene encoding the ICP36 family (p52, the major late DNA-binding protein). The ICP36 transcription unit initiates at three distinct sites which are separated by approximately 50 nucleotides and are differentially regulated during infection. At early times (8 h postinfection), only two of these start sites, the most proximal and distal site, were active whereas at late times (36 h postinfection), the middle start site was activated. Expression from this late start site was dependent upon DNA replication. Consensus TATA elements were located upstream of all three start sites, although the element upstream of the late start site was unusual in both sequence and position when compared with conventional TATA elements. Deletion analysis was used in conjunction with transient assays to define independent promoters in this region. The two early start sites and associated TATA elements functioned as separable independently regulated promoters. The region containing the late start site and TATA element but excluding either of the flanking TATA elements was inactive in transient assays. Our work establishes that the ICP36 gene is under complex early and late transcriptional regulation and that the sequences regulating transcriptional activation are temporally and spatially distinct.
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Affiliation(s)
- F S Leach
- Department of Microbiology and Immunology, Stanford University School of Medicine, California 94305
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Pande H, Campo K, Churchill MA, Zaia JA. Genomic locus for a 140 kDa structural protein (pp150) of human cytomegalovirus in strains Towne and AD169. Virus Res 1989; 12:11-8. [PMID: 2541578 DOI: 10.1016/0168-1702(89)90049-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
An HCMV specific clone was isolated from a genomic library of human cytomegalovirus (HCMV) DNA cloned into the expression vector lambda gt11. This clone (lambda 111-1) expressed an HCMV/beta-galactosidase fusion protein which was reactive with rabbit antibody prepared against purified HCMV virions and dense bodies as well as human HCMV immune serum. By probing Western blots of HCMV virion proteins or HCMV-infected cells with antibody prepared against the fusion protein, the authentic gene product of clone lambda 111-1 was identified as a high molecular weight polypeptide of 140. Probing the restriction digests of HCMV DNA with insert DNA from the immunoreactive lambda gt11 clone permitted us to localize the coding sequence for the 140 kDa polypeptide to the long unique region (map coordinates of 0.16-0.18) on HCMV Towne and AD169 genomes.
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Affiliation(s)
- H Pande
- Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010
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19
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Lee JY, Irmiere A, Gibson W. Primate cytomegalovirus assembly: evidence that DNA packaging occurs subsequent to B capsid assembly. Virology 1988; 167:87-96. [PMID: 2847426 DOI: 10.1016/0042-6822(88)90057-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Results presented here show that when cytomegalovirus (strain Colburn)-infected cells are treated with the DNA synthesis inhibitor hydroxyurea or phosphonoformate, one type of intranuclear capsid accumulates. These particles appeared to contain symmetrically organized internal material, and had a protein composition and sedimentation rate characteristic of B capsids. Radiolabeling experiments provided evidence that a population of B capsids lacking DNA is present during the course of a normal infection. These capsids sedimented slightly slower than the peak of viral DNA in the same region of the gradient, and had a ratio of DNA/protein that was estimated to be sevenfold lower than that of the faster sedimenting C capsids. DNA in both the B and C capsid regions of such gradients was found to be relatively resistant to digestion with DNase. The possibility is considered that herpesvirus B capsids lacking DNA may be counterparts of unexpanded proheads in the bacteriophage assembly pathway.
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Affiliation(s)
- J Y Lee
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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20
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Walker DG, Hudson JB. The DNA-binding properties of immediate-early and early proteins of murine cytomegalovirus. Arch Virol 1988; 102:233-43. [PMID: 2849389 DOI: 10.1007/bf01310828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The DNA-binding properties of the immediate early (IE) and early proteins induced by the murine cytomegalovirus (Smith strain) in permissively infected 3T3-L 1 cells and nonpermissively infected J774A.1 cells were characterized. Eight of 10 IE proteins and 4 of 7 early proteins had affinity for DNA (native or denatured). A 96K IE protein was observed to have affinity for denatured DNA-cellulose when synthesized in J774A.1 cells but not when synthesized 3T3-L 1 cells.
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Affiliation(s)
- D G Walker
- Division of Medical Microbiology, University of British Columbia, Vancouver, Canada
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21
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Anders DG, Gibson W. Location, transcript analysis, and partial nucleotide sequence of the cytomegalovirus gene encoding an early DNA-binding protein with similarities to ICP8 of herpes simplex virus type 1. J Virol 1988; 62:1364-72. [PMID: 2831398 PMCID: PMC253149 DOI: 10.1128/jvi.62.4.1364-1372.1988] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The results presented here locate the gene encoding an early, nonvirion, single-stranded DNA-binding protein of human and simian strains of cytomegalovirus (CMV) [HCMV(Towne) DB140 and SCMV(Colburn) DB129, respectively] and provide additional evidence that this protein is the CMV homolog of the herpes simplex virus type 1 (HSV-1) major DNA-binding protein (ICP8), as proposed earlier (D. G. Anders, A. Irmiere, and W. Gibson, J. Virol. 58:253-262). The ICP8 gene was used as a probe in Southern analyses done at moderate stringency as an approach to locating similar sequences in the CMV genome. The BamHI K and EcoRI V fragments from the center of the long unique segment of HCMV(Towne) hybridized with the ICP8 probe and were in turn used to identify corresponding sequences in the EcoRI D fragment of SCMV(Colburn). RNA prepared from SCMV(Colburn)-infected cells directed the in vitro synthesis of DB129. If the RNA was first hybridized with the cloned 12.5-kilobase EcoRI D fragment, in vitro synthesis of DB129 was specifically inhibited. Additional hybrid-arrested in vitro translation experiments with subclones spanning the EcoRI D fragment demonstrated that the DB129 gene is located in the left half of that fragment, approximately bisected by a SalI site. RNA analyses identified 3.9-, 8.9-, and 10.0-kilobase RNA species expressed from this region. A partial nucleotide sequence of the Colburn region mapping within the boundaries of the 3.9-kilobase transcript, suspected to be the primary coding species, showed significant sequence similarity to the major DNA-binding protein gene homolog identified in B95-8 Epstein-Barr virus.
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Affiliation(s)
- D G Anders
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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22
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Kinchington PR, Inchauspe G, Subak-Sharpe JH, Robey F, Hay J, Ruyechan WT. Identification and characterization of a varicella-zoster virus DNA-binding protein by using antisera directed against a predicted synthetic oligopeptide. J Virol 1988; 62:802-9. [PMID: 2828675 PMCID: PMC253635 DOI: 10.1128/jvi.62.3.802-809.1988] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We have identified, in varicella-zoster virus (VZV)-infected cells, the product of the gene predicted to code for the VZV analog of the herpes simplex virus major DNA-binding protein. The open reading frame of the VZV gene has the potential to code for a protein with a predicted molecular weight of 132,000 (a 132K protein). To detect the protein, a 12-amino-acid oligopeptide corresponding to the carboxyl terminus of the putative open reading frame was synthesized and used to prepare antisera in rabbits. The resulting antibodies reacted specifically in Western immunoblot analysis and immunoprecipitation with a single 130K polypeptide found in VZV-infected cells. The specific reactivity of the antisera with the 130K polypeptide was inhibited by the addition of synthetic peptide. Immunofluorescence studies with the antisera as probe for the 130K polypeptide suggested that this peptide is located predominantly within the nuclei of infected cells. Analysis of proteins that bind to single-stranded DNA immobilized on cellulose matrices indicated that 30 to 50% of the 130K polypeptide is capable of interacting with single-stranded DNA and that this interaction is overcome with 0.5 M NaCl. Thus, we have prepared a specific polyclonal antiserum that identifies a VZV DNA-binding protein whose properties are similar to those of the herpes simplex virus ICP8 (Vmw130) DNA-binding protein.
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Affiliation(s)
- P R Kinchington
- Department of Biochemistry, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814-4799
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23
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Wright DA, Staprans SI, Spector DH. Four phosphoproteins with common amino termini are encoded by human cytomegalovirus AD169. J Virol 1988; 62:331-40. [PMID: 2824853 PMCID: PMC250534 DOI: 10.1128/jvi.62.1.331-340.1988] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
In this report, we identify the proteins encoded by the 2.2-kilobase class of early transcripts arising from a region of the strain AD169 human cytomegalovirus genome (map units 0.682 to 0.713) which contains cell-related sequences. These transcripts, encoded by adjacent EcoRI fragments R and d, have a complex spliced structure with 5' and 3' coterminal ends. Antiserum directed against a synthetic 11-amino-acid peptide corresponding to the predicted amino terminus of the proteins was generated and found to immunoprecipitate four infected-cell proteins of 84, 50, 43, and 34 kilodaltons. These proteins were phosphorylated and were associated predominantly with the nuclei of infected cells. The 43-kilodalton protein was the most abundant of the four proteins, and its level of expression remained relatively constant throughout the infection. Expression of the other proteins increased as the infection progressed. Pulse-chase analysis failed to show a precursor-product relationship between any of the proteins. A comparison of the [35S]methionine-labeled tryptic peptide maps of the four proteins from infected cells and an in vitro-generated polypeptide derived from the putative first exon showed that all four infected-cell proteins were of viral origin and contained a common amino-terminal region.
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Affiliation(s)
- D A Wright
- Department of Biology, University of California, San Diego, La Jolla 92093
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24
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Anders DG, Kidd JR, Gibson W. Immunological characterization of an early cytomegalovirus single-strand DNA-binding protein with similarities to the HSV major DNA-binding protein. Virology 1987; 161:579-88. [PMID: 2825423 DOI: 10.1016/0042-6822(87)90154-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Monospecific polyclonal antisera were prepared against the 129-kDa, early, single-strand DNA-binding protein (DB129) of strain Colburn cytomegalovirus (CMV), and used to study its distribution in infected cells and its relatedness to a proposed human CMV (HCMV) counterpart (DB140). Indirect immunofluorescence of fixed, infected human fibroblasts showed DB129 to be localized within the intranuclear inclusions characteristic of replicating CMV. Treatment of infected cells with 50 to 100 micrograms phosphonoformic acid per milliliter resulted in the overproduction of DB129 and its accumulation within nuclei, both inside the inclusions and in surrounding areas of the nucleoplasm, whereas treatment with 500 micrograms/ml prevented inclusion formation, and DB129 was localized at discrete points throughout the infected-cell nuclei. The sera cross-reacted an estimated 10% with HCMV DB140 in an indirect immunoassay, and their use in immunofluorescence localized DB140 to the nuclear inclusions of HCMV-infected cells. Their immunological cross-reactivity, as well as their similar biochemical properties and intracellular distribution, support the likelihood that DB129 and DB140 are the protein products of homologous genes. The relationship of these proteins to the herpes simplex major DNA-binding protein is discussed.
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Affiliation(s)
- D G Anders
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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25
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Kemble GW, McCormick AL, Pereira L, Mocarski ES. A cytomegalovirus protein with properties of herpes simplex virus ICP8: partial purification of the polypeptide and map position of the gene. J Virol 1987; 61:3143-51. [PMID: 3041036 PMCID: PMC255891 DOI: 10.1128/jvi.61.10.3143-3151.1987] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We demonstrated the presence of a single-stranded DNA-binding protein in human cytomegalovirus (CMV)-infected cells with properties analogous to those of herpes simplex virus (HSV) ICP8. Using monoclonal antibody specific for the CMV protein, we analyzed its fluorescence pattern and time of synthesis, mapped the gene encoding it by using a lambda gt11 library of CMV DNA fragments, and monitored its purification by phosphocellulose and DNA-Sepharose chromatography. In all characteristics we examined, the CMV protein behaved analogously to HSV ICP8. Our results are consistent with a functional role of CMV ICP8 in viral replication that is similar to that of HSV ICP8 and with the evolutionary conservation of the gene of interest in two divergent herpesviruses.
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26
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Abstract
The application of modern biochemical techniques has led to a rapid improvement in our knowledge of the molecular biology of CMV. Several coding regions of the DNA genome have been identified with certainty and major virus-coded proteins have been given provisional names. The cascade expression of the CMV genome has been shown to be controlled by mechanisms similar to those found in other herpes viruses, together with novel post-transcriptional controls which remain to be defined. The control of CMV replication by the host involves both non-specific and specific defence mechanisms. The induction of natural killer cells and interferon early after CMV infection appears to be the most important aspects of the non-specific host defence against the virus. The cell-mediated immune response, in particular the generation of Tc cells against CMV early antigens, is probably the most important facet of the specific immune defence against CMV. When intact these defence mechanisms appear to be efficient in restricting viral replication; however, when such immunity is compromised, the balance rapidly swings in favour of the virus. As our understanding of the interaction between the host and the virus increases, it may be possible to redress the balance in such cases in favour of the host.
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