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Hume J, Lowry K, Whiley DM, Irwin AD, Bletchly C, Sweeney EL. Application of the ViroKey® SQ FLEX assay for detection of cytomegalovirus antiviral resistance. J Clin Virol 2023; 167:105556. [PMID: 37566984 DOI: 10.1016/j.jcv.2023.105556] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Revised: 07/13/2023] [Accepted: 08/03/2023] [Indexed: 08/13/2023]
Abstract
BACKGROUND Cytomegalovirus (CMV) is a viral infection which establishes lifelong latency, often reactivating and causing disease in immunosuppressed individuals, including haematopoietic stem cell transplant (HSCT) recipients. Treatment can be problematic due to antiviral resistance which substantially increases the risk of patient mortality. Diagnostic testing capabilities for CMV antiviral resistance in Australia and elsewhere have traditionally relied on gene-specific Sanger sequencing approaches, however, are now being superseded by next generation sequencing protocols. OBJECTIVE Provide a snapshot of local mutations and explore the feasibility of the ViroKeyࣨ® SQ FLEX Genotyping Assay (Vela Diagnostics Pty Ltd) by examining sequencing success. METHOD Performed sequencing on adult (n = 38) and paediatric (n = 81) plasma samples, over a large range of viral loads (above and below the assay recommended threshold of ≥1,000 International Units (IU)/mL; noting most of our paediatric samples have loads <1,000 IU/mL). RESULTS Eleven test runs (including three repeat runs; 14 to 15 samples per run) were conducted, and four runs were deemed valid. The overall individual sample success rate for the four evaluable test runs was 71.2% (42/59 samples); 80.4% (37/46) samples ≥1,000 IU/mL were valid. Ten clinically important antiviral resistance mutations were detected, the most common being A594V in the UL97 gene, found in 6 (5%) samples. CONCLUSIONS A range of technical issues were experienced, however with improvement this platform could be a useful addition to routine pathology workflows, providing timely antiviral resistance results for patients undergoing HSCT.
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Affiliation(s)
- Jocelyn Hume
- Faculty of Medicine, The University of Queensland Centre for Clinical Research (UQCCR), The University of Queensland, Brisbane, Queensland, Australia; Pathology Queensland Central Laboratory, Brisbane, Queensland, Australia
| | - Kym Lowry
- Faculty of Medicine, The University of Queensland Centre for Clinical Research (UQCCR), The University of Queensland, Brisbane, Queensland, Australia; Queensland Paediatric Infectious Diseases (QPID) Sakzewski Laboratory, Centre for Children's Health Research, Queensland Children's Hospital, Brisbane, Queensland, Australia
| | - David M Whiley
- Faculty of Medicine, The University of Queensland Centre for Clinical Research (UQCCR), The University of Queensland, Brisbane, Queensland, Australia; Pathology Queensland Central Laboratory, Brisbane, Queensland, Australia
| | - Adam D Irwin
- Faculty of Medicine, The University of Queensland Centre for Clinical Research (UQCCR), The University of Queensland, Brisbane, Queensland, Australia; Infection Management and Prevention Service, Queensland Children's Hospital, Brisbane, Queensland, Australia
| | - Cheryl Bletchly
- Pathology Queensland Central Laboratory, Brisbane, Queensland, Australia
| | - Emma L Sweeney
- Faculty of Medicine, The University of Queensland Centre for Clinical Research (UQCCR), The University of Queensland, Brisbane, Queensland, Australia.
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Kapoor A, Ghosh AK, Forman M, Hu X, Ye W, Southall N, Marugan J, Keyes RF, Smith BC, Meyers DJ, Ferrer M, Arav-Boger R. Validation and Characterization of Five Distinct Novel Inhibitors of Human Cytomegalovirus. J Med Chem 2020; 63:3896-3907. [PMID: 32191456 PMCID: PMC7386824 DOI: 10.1021/acs.jmedchem.9b01501] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The critical consequences of human cytomegalovirus (HCMV) infection in the transplant population and in congenitally infected infants, the limited treatment options for HCMV, and the rise of resistant mutants toward existing therapies has fueled the search for new anti-HCMV agents. A pp28-luciferase recombinant HCMV was used as a reporter system for high-throughput screening of HCMV inhibitors. Approximately 400 000 compounds from existing libraries were screened. Subsequent validation assays using resynthesized compounds, several virus strains, and detailed virology assays resulted in the identification of five structurally unique and selective HCMV inhibitors, active at sub to low micromolar concentrations. Further characterization revealed that each compound inhibited a specific stage of HCMV replication. One compound was also active against herpes simplex virus (HSV1 and HSV2), and another compound was active against Epstein-Barr virus (EBV). Drug combination studies revealed that all five compounds were additive with ganciclovir or letermovir. Future studies will focus on optimization of these new anti-HCMV compounds along with mechanistic studies.
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Affiliation(s)
- Arun Kapoor
- Department of Pediatrics, Division of Infectious Disease, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Ayan K. Ghosh
- Department of Pediatrics, Division of Infectious Disease, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Michael Forman
- Department of Pathology, Johns Hopkins University, Baltimore, Maryland 21287, USA
| | - Xin Hu
- National Center for Advancing Translational Sciences (NCATS), National Institute of Health, Bethesda, MD 20850, USA
| | - Wenjuan Ye
- National Center for Advancing Translational Sciences (NCATS), National Institute of Health, Bethesda, MD 20850, USA
| | - Noel Southall
- National Center for Advancing Translational Sciences (NCATS), National Institute of Health, Bethesda, MD 20850, USA
| | - Juan Marugan
- National Center for Advancing Translational Sciences (NCATS), National Institute of Health, Bethesda, MD 20850, USA
| | - Robert F. Keyes
- Department of Biochemistry, Program in Chemical Biology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Brian C. Smith
- Department of Biochemistry, Program in Chemical Biology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - David J. Meyers
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
| | - Marc Ferrer
- National Center for Advancing Translational Sciences (NCATS), National Institute of Health, Bethesda, MD 20850, USA
| | - Ravit Arav-Boger
- Department of Pediatrics, Division of Infectious Disease, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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3
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Drug-resistant cytomegalovirus: clinical implications of specific mutations. Curr Opin Organ Transplant 2018; 23:388-394. [DOI: 10.1097/mot.0000000000000541] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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4
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Yamada KH, Majima R, Yamaguchi T, Inoue N. Characterization of phenyl pyrimidine derivatives that inhibit cytomegalovirus immediate-early gene expression. Antivir Chem Chemother 2018; 26:2040206618763193. [PMID: 29546767 PMCID: PMC5890547 DOI: 10.1177/2040206618763193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Background Previously, we established a reporter cell line for human cytomegalovirus and screened anti-human cytomegalovirus compounds using the cell line. In this study, we characterized one of the identified compounds, 2,4-diamino-6–(4-methoxyphenyl)pyrimidine (coded as 35C10). Methods 50% Effective concentrations (EC50s) and 50% cytotoxic concentrations (CC50s) of 35C10 and its derivatives in human fibroblasts were determined by X-gal staining of the cells infected with human cytomegalovirus Towne strain expressing β-galactosidase. Results EC50 and CC50 of 35C10 were 4.3 µM and >200 µM, respectively. Among several 35C10 derivatives, only one lacking 4-amino group of pyrimidine showed a similar EC50. 35C10 weakly inhibited murine cytomegalovirus, herpes simplex virus type 1, and varicella-zoster virus. A “time of addition” experiment suggested that 35C10 inhibited an early phase of the infection. Although 35C10 did not inhibit viral attachment to the cells nor the delivery of viral DNA to the nuclei, it decreased the number of infected cells expressing immediate-early 1 and 2 (IE1/IE2) proteins. 35C10 also inhibited the activation of a promoter for TRL4 in the reporter cells upon human cytomegalovirus infection, but not in the same reporter cells transfected with a plasmid expressing IE2. Conclusion Our findings suggest that 35C10 is a novel compound that inhibits IE gene expression in human cytomegalovirus-infected cells.
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Affiliation(s)
- Koh-Hei Yamada
- 1 Department of Microbiology and Immunology, Gifu Pharmaceutical University, Gifu, Japan
| | - Ryuichi Majima
- 1 Department of Microbiology and Immunology, Gifu Pharmaceutical University, Gifu, Japan
| | - Toyofumi Yamaguchi
- 2 Department of Biosciences, Teikyo University of Science and Technology, Tokyo, Japan
| | - Naoki Inoue
- 1 Department of Microbiology and Immunology, Gifu Pharmaceutical University, Gifu, Japan
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A Luciferase Gene Driven by an Alphaherpesviral Promoter Also Responds to Immediate Early Antigens of the Betaherpesvirus HCMV, Allowing Comparative Analyses of Different Human Herpesviruses in One Reporter Cell Line. PLoS One 2017; 12:e0169580. [PMID: 28060895 PMCID: PMC5217978 DOI: 10.1371/journal.pone.0169580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 12/19/2016] [Indexed: 11/19/2022] Open
Abstract
Widely used methods for quantification of human cytomegalovirus (HCMV) infection in cell culture such as immunoblotting or plaque reduction assays are generally restricted to low throughput and require time-consuming evaluation. Up to now, only few HCMV reporter cell lines have been generated to overcome these restrictions and they are afflicted with other limitations because permanently expandable cell lines are normally not fully permissive to HCMV. In this work, a previously existing epithelial cell line hosting a luciferase gene under control of a Varicella-zoster virus promoter was adopted to investigate HCMV infection. The cells were susceptible to different HCMV strains at infection efficiencies that corresponded to their respective degree of epithelial cell tropism. Expression of early and late viral antigens, formation of nuclear inclusions, release of infectious virus progeny, and focal growth indicated productive viral replication. However, viral release and spread occurred at lower levels than in primary cell lines which appears to be due to a malfunction of virion morphogenesis during the nuclear stage. Expression of the luciferase reporter gene was specifically induced in HCMV infected cultures as a function of the virus dose and dependent on viral immediate early gene expression. The level of reporter activity accurately reflected infection efficiencies as determined by viral antigen immunostaining, and hence could discriminate the cell tropism of the tested virus strains. As proof-of-principle, we demonstrate that this cell line is applicable to evaluate drug resistance of clinical HCMV isolates and the neutralization capacity of human sera, and that it allows comparative and simultaneous analysis of HCMV and human herpes simplex virus type 1. In summary, the permanent epithelial reporter cell line allows robust, rapid and objective quantitation of HCMV infection and it will be particularly useful in higher throughput analyses as well as in comparative analyses of different human herpesviruses.
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How I treat resistant cytomegalovirus infection in hematopoietic cell transplantation recipients. Blood 2016; 128:2624-2636. [PMID: 27760756 DOI: 10.1182/blood-2016-06-688432] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 10/17/2016] [Indexed: 12/20/2022] Open
Abstract
Cytomegalovirus (CMV) infection is a significant complication in hematopoietic cell transplantation (HCT) recipients. Four antiviral drugs are used for preventing or treating CMV: ganciclovir, valganciclovir, foscarnet, and cidofovir. With prolonged and repeated use of these drugs, CMV can become resistant to standard therapy, resulting in increased morbidity and mortality, especially in HCT recipients. Antiviral drug resistance should be suspected when CMV viremia (DNAemia or antigenemia) fails to improve or continue to increase after 2 weeks of appropriately dosed and delivered antiviral therapy. CMV resistance is diagnosed by detecting specific genetic mutations. UL97 mutations confer resistance to ganciclovir and valganciclovir, and a UL54 mutation confers multidrug resistance. Risk factors for resistance include prolonged or previous anti-CMV drug exposure or inadequate dosing, absorption, or bioavailability. Host risk factors include type of HCT and degree of immunosuppression. Depending on the genotyping results, multiple strategies can be adopted to treat resistant CMV infections, albeit no randomized clinical trials exist so far, after reducing immunosuppression (if possible): ganciclovir dose escalation, ganciclovir and foscarnet combination, and adjunct therapy such as CMV-specific cytotoxic T-lymphocyte infusions. Novel therapies such as maribavir, brincidofovir, and letermovir should be further studied for treatment of resistant CMV.
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Andouard D, Mazeron MC, Ligat G, Couvreux A, Pouteil-Noble C, Cahen R, Yasdanpanah Y, Deering M, Viget N, Alain S, Hantz S. Contrasting effect of new HCMV pUL54 mutations on antiviral drug susceptibility: Benefits and limits of 3D analysis. Antiviral Res 2016; 129:115-119. [PMID: 26872863 DOI: 10.1016/j.antiviral.2016.02.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 01/29/2016] [Accepted: 02/01/2016] [Indexed: 10/22/2022]
Abstract
Human cytomegalovirus (HCMV) resistance to antiviral drugs is a major drawback of repeated or long-duration treatment in immunocompromised patients. Resistance testing is usually performed by genotypic assays. For accurate interpretation of these assays, the role of new mutations in HCMV resistance has to be assessed. Two previously unknown UL54 single point mutations (D515Y and V787A) were characterized for phenotypic drug-resistance by marker transfer analysis using bacterial artificial chromosome (BAC) mutagenesis. Increases in 50% inhibitory concentrations of ganciclovir and foscarnet were found for both mutated recombinant strains showing that mutations D515Y and V787A induce resistance to both antivirals. Importantly, none of those impacted the viral growth kinetics. For a better understanding of their molecular resistance mechanisms, a 3D homology model was used to localize the mutated amino-acids in functional domains of UL54 and predict their impact on UL54 function and resistance. However, 3D homology model analysis has limits and phenotypic characterization using BAC-HCMV is still essential to measure the role of unknown mutations.
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Affiliation(s)
- D Andouard
- Univ. Limoges, UMR, 1092, Limoges, France; INSERM, UMR, 1092, Limoges, France; CHU Limoges, Laboratoire de Bactériologie-Virologie-Hygiène, National Reference Center for Cytomegaloviruses (NRC), Limoges, France
| | - M-C Mazeron
- CHU Saint Louis, Laboratoire de Bactériologie-Virologie, NRC-Associated Laboratory, Paris, France
| | - G Ligat
- Univ. Limoges, UMR, 1092, Limoges, France; INSERM, UMR, 1092, Limoges, France; CHU Limoges, Laboratoire de Bactériologie-Virologie-Hygiène, National Reference Center for Cytomegaloviruses (NRC), Limoges, France
| | - A Couvreux
- Univ. Limoges, UMR, 1092, Limoges, France; INSERM, UMR, 1092, Limoges, France; CHU Limoges, Laboratoire de Bactériologie-Virologie-Hygiène, National Reference Center for Cytomegaloviruses (NRC), Limoges, France
| | - C Pouteil-Noble
- CHU Lyon, Service de Transplantation rénale, Hôpital Edouard Herriot, Lyon, France
| | - R Cahen
- CHU Lyon, Service de Transplantation rénale, Hôpital Edouard Herriot, Lyon, France
| | - Y Yasdanpanah
- CHU Bichat, Service de Maladies infectieuses et Tropicales, Paris, France
| | - M Deering
- Univ. Limoges, UMR, 1092, Limoges, France; INSERM, UMR, 1092, Limoges, France; CHU Limoges, Laboratoire de Bactériologie-Virologie-Hygiène, National Reference Center for Cytomegaloviruses (NRC), Limoges, France
| | - N Viget
- Department of Infectious Diseases, Lille School of Medicine, Tourcoing Hospital, Tourcoing, France
| | - S Alain
- Univ. Limoges, UMR, 1092, Limoges, France; INSERM, UMR, 1092, Limoges, France; CHU Limoges, Laboratoire de Bactériologie-Virologie-Hygiène, National Reference Center for Cytomegaloviruses (NRC), Limoges, France
| | - S Hantz
- Univ. Limoges, UMR, 1092, Limoges, France; INSERM, UMR, 1092, Limoges, France; CHU Limoges, Laboratoire de Bactériologie-Virologie-Hygiène, National Reference Center for Cytomegaloviruses (NRC), Limoges, France.
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Komatsu TE, Pikis A, Naeger LK, Harrington PR. Resistance of human cytomegalovirus to ganciclovir/valganciclovir: A comprehensive review of putative resistance pathways. Antiviral Res 2014; 101:12-25. [DOI: 10.1016/j.antiviral.2013.10.011] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 10/20/2013] [Accepted: 10/21/2013] [Indexed: 11/26/2022]
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Rapid detection of human cytomegalovirus UL97 and UL54 mutations directly from patient samples. J Clin Microbiol 2013; 51:2354-9. [PMID: 23678068 DOI: 10.1128/jcm.00611-13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human cytomegalovirus (CMV) is a significant contributor to morbidity and mortality in immunocompromised patients, particularly in the transplant setting. The availability of anti-CMV drugs has improved treatment, but drug resistance is an emerging problem. Here, we describe an improved, rapid, sequencing-based assay for the two genes in CMV where drug resistance occurs, the UL97 and UL54 genes. This assay is performed in 96-well format with a single master mix and provides clinical results within 2 days. It sequences codons 440 to 645 in the UL97 gene and codons 255 to 1028 in the UL54 gene with a limit of detection of 240 IU/ml. With this assay, we tested 43 specimens that had previously been tested for UL97 drug resistance and identified 3 with UL54 mutations. One of these patients had no concurrent UL97 mutation, pointing toward the need for an assay that facilitates dual UL97/UL54 gene testing for complete resistance profiling.
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An infectious HHV-6B isolate from a healthy adult with chromosomally integrated virus and a reporter based relative viral titer assay. Virus Res 2013; 173:280-5. [DOI: 10.1016/j.virusres.2013.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 02/03/2013] [Accepted: 02/04/2013] [Indexed: 02/05/2023]
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Recombinant phenotyping of cytomegalovirus UL54 mutations that emerged during cell passages in the presence of either ganciclovir or foscarnet. Antimicrob Agents Chemother 2011; 55:4019-27. [PMID: 21709106 DOI: 10.1128/aac.00334-11] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Selection of human cytomegalovirus variants in the presence of ganciclovir or foscarnet led to 18 DNA polymerase mutations, 14 of which had not been previously studied. Using bacterial artificial chromosome technology, each of these mutations was individually transferred into the genome of a reference strain. Following reconstitution of infectious viral stocks, each mutant was assessed for its drug susceptibility and growth kinetics in cell culture. Computer-assisted three-dimensional (3D) modeling of the polymerase was also used to position each of the mutations in one of four proposed structural domains and to predict their influence on structural stability of the protein. Among the 10 DNA polymerase mutations selected with ganciclovir, 7 (P488R, C539R, L545S, V787L, V812L, P829S, and L862F) were associated with ganciclovir resistance, whereas 2 (F595I and V946L) conferred only foscarnet resistance. Among the eight mutations selected with foscarnet, only two (T552N and S585A) conferred foscarnet resistance, whereas four (N408D, K500N, L802V, and L957F) had an impact on ganciclovir susceptibility. Surprisingly, the combination of mutations, some of which were not associated with resistance for a specific antiviral, resulted in increasing resistance effects. 3D modeling suggested that none of the mutated residues were directly involved in the polymerase catalytic site but rather had an influence on drug susceptibility by modifying the structural flexibility of the protein. Our study significantly adds to the number of DNA polymerase mutations conferring in vitro drug resistance and emphasizes the point that evaluation of individual mutations may not accurately reflect the phenotype conferred by multiple mutations.
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He R, Sandford G, Hayward GS, Burns WH, Posner GH, Forman M, Arav-Boger R. Recombinant luciferase-expressing human cytomegalovirus (CMV) for evaluation of CMV inhibitors. Virol J 2011; 8:40. [PMID: 21269468 PMCID: PMC3041771 DOI: 10.1186/1743-422x-8-40] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 01/26/2011] [Indexed: 01/10/2023] Open
Abstract
Recombinant Towne CMV expressing luciferase under the control of CMV-DNA polymerase (POL) or the late pp28 (UL99) promoters were evaluated for potential application in high-throughput screening of anti-viral compounds. POL-and pp28-luciferase displayed maximal expression 48 and 72 hours post infection, respectively. The pp28-luciferase virus achieved a wider dynamic range of luciferase expression (6-7 logs) and was selected for testing of inhibition by five anti-viral compounds. Luciferase expression highly correlated with plaque reduction and real-time PCR. The pp28-luciferase reporter system is rapid, reproducible, and highly sensitive. It may be applied to screening of novel anti-CMV compounds.
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Affiliation(s)
- Ran He
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Abstract
The study of human cytomegalovirus (HCMV) antiviral drug resistance has enhanced knowledge of the virological targets and the mechanisms of antiviral activity. The currently approved drugs, ganciclovir (GCV), foscarnet (FOS), and cidofovir (CDV), target the viral DNA polymerase. GCV anabolism also requires phosphorylation by the virus-encoded UL97 kinase. GCV resistance mutations have been identified in both genes, while FOS and CDV mutations occur only in the DNA polymerase gene. Confirmation of resistance mutations requires phenotypic analysis; however, phenotypic assays are too time-consuming for diagnostic purposes. Genotypic assays based on sequencing provide more rapid results but are dependent on prior validation by phenotypic methods. Reports from many laboratories have produced an evolving list of confirmed resistance mutations, although differences in interpretation have led to some confusion. Recombinant phenotyping methods performed in a few research laboratories have resolved some of the conflicting results. Treatment options for drug-resistant HCMV infections are complex and have not been subjected to controlled clinical trials, although consensus guidelines have been proposed. This review summarizes the virological and clinical data pertaining to HCMV antiviral drug resistance.
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In vivo imaging assay for the convenient evaluation of antiviral compounds against cytomegalovirus in mice. Antiviral Res 2010; 88:45-52. [DOI: 10.1016/j.antiviral.2010.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Revised: 06/29/2010] [Accepted: 07/06/2010] [Indexed: 11/22/2022]
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Chevillotte M, von Einem J, Meier BM, Lin FM, Kestler HA, Mertens T. A new tool linking human cytomegalovirus drug resistance mutations to resistance phenotypes. Antiviral Res 2010; 85:318-27. [DOI: 10.1016/j.antiviral.2009.10.004] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 10/02/2009] [Accepted: 10/10/2009] [Indexed: 11/25/2022]
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Luganini A, Caposio P, Mondini M, Landolfo S, Gribaudo G. New cell-based indicator assays for the detection of human cytomegalovirus infection and screening of inhibitors of viral immediate-early 2 protein activity. J Appl Microbiol 2009; 105:1791-801. [PMID: 19120629 DOI: 10.1111/j.1365-2672.2008.03927.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIMS Expression of early (E) genes of human cytomegalovirus (HCMV) is stimulated cooperatively by the activities of host cell transcription factors and the viral immediate-early 2 (IE2) protein. Taking advantage of the IE2-dependent inducibility of E gene promoters, in this study, we generated cell-based assays in which the expression of the enhanced green fluorescence protein (EGFP) reporter gene was driven by the UL54 or UL112/113 E promoters. METHODS AND RESULTS Cell clones derived from a stably transfected human cell line permissive to HCMV replication showed a specific and inducible dose- and time-dependent EGFP response to HCMV infection. The sensitivity of these indicator cells for detecting infectious particles of clinical isolates of HCMV was comparable to that of a conventional plaque assay. The HCMV-induced EGFP expression was completely prevented by treatment of indicator cells with fomivirsen, an antisense oligodeoxynucleotide designed to block IE2 expression, and this inhibitory activity was also observed when the IE2 protein alone was constitutively expressed in EGFP indicator cells. CONCLUSIONS The EGFP-based cell assays have proved to be a rapid, sensitive, quantitative and specific system for detection of HCMV and selection of antivirals. SIGNIFICANCE AND IMPACT OF THE STUDY These new cell-based assays can be exploited as functional assays to detect infectious HCMV particles, as well as to screen antiviral compounds that interfere with IE2 activity.
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Affiliation(s)
- A Luganini
- Department of Public Health and Microbiology, University of Torino, Torino, Italy
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Fluorescence-based assay for phenotypic characterization of human cytomegalovirus polymerase mutations regarding drug susceptibility and viral replicative fitness. Antimicrob Agents Chemother 2009; 53:3752-61. [PMID: 19546362 DOI: 10.1128/aac.00165-09] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
One essential prerequisite for genotypic drug susceptibility testing of human cytomegalovirus (HCMV) is the phenotypic characterization of mutations identified in the viral protein kinase gene UL97 and the viral DNA polymerase gene UL54 regarding their quantitative impact on drug susceptibility. We developed a new method for phenotypic characterization of UL54 mutations with regard to polymerase activity, viral replication, and drug susceptibility. To determine the most suitable viral indicator gene, enhanced green fluorescence protein was C-terminally fused to the HCMV early-late protein UL83 (pp65) or the late proteins UL32 (pp150) and UL99 (pp28), resulting in reporter viruses vTB65g, vTB150g, and vTB28g. vTB65g proved to be superior to the other constructs due to its favorable signal-to-noise ratio and was therefore used to establish the optimum conditions for our assay. The UL54 E756K and D413E mutations were introduced into vTB65g by markerless bacterial artificial chromosome mutagenesis, resulting in virus strains vE756Kg and vD413Eg. The drug susceptibility phenotypes of vE756Kg and vD413Eg were comparable to those previously reported. Furthermore, we found a reduced replicative fitness of vE756Kg by measuring fluorescence intensity as well as by conventional virus growth kinetics. Decreased fluorescence signals of vE756Kg- and vD413Eg-infected cells at late times of infection suggested a reduced polymerase activity, which was confirmed by real-time PCR quantification of the newly synthesized viral DNAs. This new fluorescence-based assay is a highly reproducible method for the phenotypic characterization of mutations potentially influencing drug susceptibility, viral replicative fitness, and polymerase activity of HCMV after marker transfer.
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Chou S. Cytomegalovirus UL97 mutations in the era of ganciclovir and maribavir. Rev Med Virol 2008; 18:233-46. [PMID: 18383425 DOI: 10.1002/rmv.574] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Mutations in the human CMV UL97 kinase gene are a major mechanism of viral resistance to two anti-CMV drugs, ganciclovir (GCV) and maribavir (MBV). GCV, the most widely used and established therapy for CMV, is a substrate for the UL97 kinase. Well-characterised GCV-resistance mutations at UL97 codons 460, 520 and 590-607 impair the phosphorylation of GCV that is necessary for its antiviral activity, presumably by altering substrate recognition. In contrast, MBV is an inhibitor of the UL97 kinase and is the first new CMV therapy to reach later stage clinical trials in many years. No MBV-resistant CMV isolates have yet been detected in clinical trials, but after culture propagation under drug, UL97 mutations that confer moderate to high-level MBV resistance have been identified at codons 353, 397, 409 and 411. These mutations are located upstream of the GCV-resistance mutations and are close to the ATP-binding and catalytic domains common to all kinases, consistent with MBV acting as a small molecule ATP-competitive kinase inhibitor. So far, no UL97 mutations are known to confer resistance to both GCV and MBV.
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Affiliation(s)
- Sunwen Chou
- Division of Infectious Diseases, Oregon Health and Science University, Portland, Oregon, USA.
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Establishment of a cell-based assay for screening of compounds inhibiting very early events in the cytomegalovirus replication cycle and characterization of a compound identified using the assay. Antimicrob Agents Chemother 2008; 52:2420-7. [PMID: 18458124 DOI: 10.1128/aac.00134-08] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To simplify the detection of infectious human cytomegalovirus (HCMV), we generated a cell line that produced luciferase in a dose-dependent manner upon HCMV infection. Using this cell line, we identified anti-HCMV compounds from a diverse library of 9,600 compounds. One of them, 1-(3,5-dichloro-4-pyridyl)piperidine-4-carboxamide (DPPC), was effective against HCMV (Towne strain) infection of human lung fibroblast cells at a 50% effective concentration of 2.5 microM. DPPC also inhibited the growth of clinical HCMV isolates and guinea pig and mouse cytomegaloviruses. Experiments using various time frames for treatment of the cells with DPPC demonstrated that DPPC was effective during the first 24 h after HCMV infection. DPPC treatment decreased not only viral DNA replication but also IE1 and IE2 expression at mRNA and protein levels in the HCMV-infected cells. However, DPPC did not inhibit the attachment of HCMV particles to the cell surface. DPPC is a unique compound that targets the very early phase of cytomegalovirus infection, probably by disrupting a pathway that is important after viral entry but before immediate-early gene expression.
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Bonnafous P, Naesens L, Petrella S, Gautheret-Dejean A, Boutolleau D, Sougakoff W, Agut H. Different Mutations in the HHV-6 DNA Polymerase Gene Accounting for Resistance to Foscarnet. Antivir Ther 2007. [DOI: 10.1177/135965350701200608] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Background Human herpesvirus 6 (HHV-6), which is closely related to human cytomegalovirus, is sensitive to foscarnet (PFA). Up to now, the resistance of HHV-6 to PFA has not been investigated. Objectives The goal of the study was to isolate and characterize PFA-resistant HHV-6 mutants in order to determine the mechanisms of resistance to the drug. Methods PFA-resistant viruses, isolated in MT4 cell culture under increasing concentrations of PFA, were characterized phenotypically and genotypically. The mutations identified in the HHV-6 DNA polymerase gene were evaluated in a functional assay using recombinant mutated forms of the enzyme, and their effect on protein structure was analysed in a three-dimensional model derived from available structures of DNA polymerases. Results Two mutants were selected and were 8- and 15-fold more resistant to PFA than the wild-type strain. Four amino acid changes were detected in the HHV-6 DNA polymerase in association with PFA resistance: T435R, H507Y, C525S, located in the δC conserved domain, and F292S. Either alone or in combination, these substitutions significantly decreased the inhibitory effect of PFA at the level of the polymerase, as measured by the incorporation of radiolabeled nucleotides in a DNA elongation assay. In the three-dimensional model of HHV-6 DNA polymerase structure the four changes were not located within the putative catalytic site, but they might induce either a disturbance of local conformation or a restricted access of PFA to its target site. Conclusion This first characterization of HHV-6 resistance to PFA highlights the role of distinct DNA polymerase gene mutations.
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Affiliation(s)
- Pascale Bonnafous
- Université Pierre et Marie Curie-Paris 6, EA2387, Groupe hospitalier Pitié-Salpêtrière, Paris, France
| | - Lieve Naesens
- Laboratory of Virology and Chemotherapy Rega Institute for Medical Research, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Stéphanie Petrella
- INSERM, U655-LRMA, Site Pitié-Salpêtrière AP-HP, Université Pierre et Marie Curie-Paris 6, Paris, France
| | - Agnès Gautheret-Dejean
- Université Pierre et Marie Curie-Paris 6, EA2387, Groupe hospitalier Pitié-Salpêtrière, Paris, France
- Laboratoire de Microbiologie, Faculté des Sciences Pharmaceutiques et Biologiques, Paris, France
| | - David Boutolleau
- Université Pierre et Marie Curie-Paris 6, EA2387, Groupe hospitalier Pitié-Salpêtrière, Paris, France
| | - Wladimir Sougakoff
- INSERM, U655-LRMA, Site Pitié-Salpêtrière AP-HP, Université Pierre et Marie Curie-Paris 6, Paris, France
| | - Henri Agut
- Université Pierre et Marie Curie-Paris 6, EA2387, Groupe hospitalier Pitié-Salpêtrière, Paris, France
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