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Feltrin C, Oliveira Simões CM, Marques Sincero TC. Development of a cell-based reporter assay for detection of Human alphaherpesviruses. Mol Cell Probes 2022; 62:101806. [DOI: 10.1016/j.mcp.2022.101806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 02/13/2022] [Accepted: 03/02/2022] [Indexed: 11/28/2022]
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Hayes PR, Przybycien TM, Schneider JW. Viral adventitious agent detection using laser force cytology: Intrinsic cell property changes with infection and comparison to in vitro testing. Biotechnol Bioeng 2021; 119:134-144. [PMID: 34633076 DOI: 10.1002/bit.27957] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 08/02/2021] [Accepted: 10/04/2021] [Indexed: 11/11/2022]
Abstract
Adventitious agent testing in biomanufacturing requires assays of broad detection capability to screen for as many infectious agents as possible. The current gold standard for general infectious adventitious virus screening is the in vitro assay in which test articles are cultured onto a panel of different cell lines and observed for cytopathic effect (CPE). However, this assay is inherently subjective due to the nature of visual observation of cell morphology and labor and time intensive, requiring highly trained personnel to identify CPE. Laser force cytology (LFC) is an alternative, automated analytical method that uses a combination of optical and fluidic forces along with imaging to objectively and quantitatively assess CPE in cell culture. Importantly, because LFC uses no labels or antibodies, the assay is appropriate for general adventitious agent testing. Using LFC, changes in cellular features associated with virally infected cells were identified using principal component analysis. Using these features of infected cells, the sensitivity and earliness of detection with LFC was directly compared with the in vitro assay for a diverse panel of viruses incubated with chinese hamster ovary (CHO), Vero, and Medical Research Council cell strain 5 (MRC-5) cells. LFC detected viral infection with a sensitivity equal to the in vitro assay on average, but in certain virus and cell combinations including mouse minute virus (MMV) and reovirus 3 in CHO cells, detection was 4 days earlier and for MMV, the limit of detection was 10-fold lower. Overall, these results demonstrate the ability of LFC to serve as a biopharmaceutical adventitious agent testing methodology with sensitivity equivalent to the in vitro assay, but in an objective and automated manner.
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Affiliation(s)
- Peter R Hayes
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Todd M Przybycien
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, New York, USA
| | - James W Schneider
- Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
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A flow cytometric granularity assay for the quantification of infectious virus. Vaccine 2019; 37:7090-7099. [PMID: 31630940 DOI: 10.1016/j.vaccine.2019.02.059] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/05/2019] [Accepted: 02/25/2019] [Indexed: 01/27/2023]
Abstract
A flow cytometry-based assay was developed to assess the infective titer of two recombinant viruses: a recombinant herpes simplex type 2 (rHSV-2) and a recombinant canary pox (rALVAC.gfp). This method uses granularity of infected Vero and QT-35 cells, respectively, and correlates this to the infectious titer of virus samples. The percent of the cell populations with a high level of granularity could accurately be correlated to viral titers obtained through a traditional plaque assay, with R2 values greater than 0.8 using a semi-logarithmic scale. This approach offers a rapid, high-throughput method for infectious virus titration with similar accuracy to a traditional plaque assay.
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Easy In Vitro Synthesis of Optimised Functioning Reporter mRNA from Common eGFP Plasmid. Mol Biotechnol 2018; 60:762-771. [PMID: 30120676 DOI: 10.1007/s12033-018-0112-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
The extensive growth in number and importance of experiments and clinical-aimed techniques based solely or majorly on the activity of RNA strands, e.g. CRSPR/Cas9 and siRNA, has put emphasis on the necessity of standardisation of experiments with RNA. Considering RNA degradation during its handling seems to be a major hindrance in all RNA-based tools, the assessment of its integrity is of utmost importance. Furthermore, evaluating whether the RNA to be transfected is intact requires time-consuming electrophoresis protocol. In view of the RNA lability and the necessity for controlling experiments performed with this molecule, the transfection of a reporter mRNA may be of aid in optimising experiments. Nevertheless, commercial reporter mRNAs are far less available than plasmids for such purpose. Thus, in this work, we aimed at the optimisation of an easily performed protocol to produce a suitable eGFP mRNA. By utilising molecular biology kits customarily employed in molecular biology laboratories working with RNA-based techniques and starting from any eGFP coding vector, we produced four mRNA molecules: (1) eGFP mRNA (non-polyadenylated); (2) Kozak-eGFP mRNA (non-polyadenylated, produced from the Kozak-containing amplicon); (3) eGFP-PolyA mRNA (polyadenylated); (4) Kozak-eGFP-PolyA mRNA (containing both signals, Kozak sequence and poly(A) tail). These mRNA molecules were transfected into HEK 293 FT cells, readily transfectable, and into the MDBK bovine lineage, which has been observed as difficult-to-transfect DNA constructs. eGFP expression could be detected both by flow cytometry and by fluorescence microscopy after transfection with the polyadenylated mRNAs. Upon cytometric analysis, we noted a marked difference among the mRNA groups (p < 0.01), both in fluorescent population percentage and in florescence intensity. We showed here the necessity of the polyadenylation step in order to achieve cell expression of the eGFP observable under fluorescence microscopy. The presence of the Kozak sequence, as a 5' element, seems to augment significantly the level of protein produced upon mRNA transfection. We presented here an easy protocol to allow production of functioning mRNAs from any DNA construct. The molecules produced may aid in the standardisation and controlling most of the RNA-related experiments as well as it gives proper guidance for researchers performing expression of other proteins through mRNA transfection.
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Barreira LAC, Scheucher PS, Romeiro MF, Serra LL, Badra SJ, Souza WMD, Figueiredo LTM. Evaluating the use of fluorescence-based flow cytometry assay for dengue diagnosis using peripheral blood mononuclear cells. Rev Soc Bras Med Trop 2018; 51:168-173. [PMID: 29768549 DOI: 10.1590/0037-8682-0404-2017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 03/20/2018] [Indexed: 11/21/2022] Open
Abstract
INTRODUCTION Dengue virus (DENV) is the most important arthropod-borne viral disease worldwide with an estimated 50 million infections occurring each year. METHODS In this study, we present a flow cytometry assay (FACS) for diagnosing DENV, and compare its results with those of the non-structural protein 1 (NS1) immunochromatographic assay and reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS All three assays identified 29.1% (39/134) of the patients as dengue-positive. The FACS approach and real-time RT-PCR detected the DENV in 39 and 44 samples, respectively. On the other hand, the immunochromatographic assay detected the NS1 protein in 40.1% (56/134) of the patients. The Cohen's kappa coefficient analysis revealed a substantial agreement among the three methods. CONCLUSIONS The FACS approach may be a useful alternative for dengue diagnosis and can be implemented in public and private laboratories.
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Affiliation(s)
- Luzia Aparecida Costa Barreira
- Centro de Pesquisa em Virologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - Priscila Santos Scheucher
- Laboratório de Hematologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - Marilia Farignoli Romeiro
- Centro de Pesquisa em Virologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - Leonardo La Serra
- Centro de Pesquisa em Virologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - Soraya Jabur Badra
- Centro de Pesquisa em Virologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - William Marciel de Souza
- Centro de Pesquisa em Virologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
| | - Luiz Tadeu Moraes Figueiredo
- Centro de Pesquisa em Virologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil
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Li J, Zhu W, Wang H, Li J, Zhang Q, He Y, Li J, Fu J, Li D, Liang G. Rapid, specific detection of alphaviruses from tissue cultures using a replicon-defective reporter gene assay. PLoS One 2012; 7:e33007. [PMID: 22427930 PMCID: PMC3299729 DOI: 10.1371/journal.pone.0033007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 02/02/2012] [Indexed: 12/22/2022] Open
Abstract
We established a rapid, specific technique for detecting alphaviruses using a replicon-defective reporter gene assay derived from the Sindbis virus XJ-160. The pVaXJ expression vector containing the XJ-160 genome was engineered to form the expression vectors pVaXJ-EGFP expressing enhanced green fluorescence protein (EGFP) or pVaXJ-GLuc expressing Gaussia luciferase (GLuc). The replicon-defective reporter plasmids pVaXJ-EGFPΔnsp4 and pVaXJ-GLucΔnsp4 were constructed by deleting 1139 bp in the non-structural protein 4 (nsP4) gene. The deletion in the nsP4 gene prevented the defective replicons from replicating and expressing reporter genes in transfected BHK-21 cells. However, when these transfected cells were infected with an alphavirus, the non-structural proteins expressed by the alphavirus could act on the defective replicons in trans and induce the expression of the reporter genes. The replicon-defective plasmids were used to visualize the presence of alphavirus qualitatively or detect it quantitatively. Specificity tests showed that this assay could detect a variety of alphaviruses from tissue cultures, while other RNA viruses, such as Japanese encephalitis virus and Tahyna virus, gave negative results with this system. Sensitivity tests showed that the limit of detection (LOD) of this replicon-defective assay is between 1 and 10 PFU for Sindbis viruses. These results indicate that, with the help of the replicon-defective alphavirus detection technique, we can specifically, sensitively, and rapidly detect alphaviruses in tissue cultures. The detection technique constructed here may be well suited for use in clinical examination and epidemiological surveillance, as well as for rapid screening of potential viral biological warfare agents.
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Affiliation(s)
- Jiangjiao Li
- Department of Viral Encephalitis, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention (IVDC, China CDC), Beijing, China
| | - Wuyang Zhu
- Department of Viral Encephalitis, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention (IVDC, China CDC), Beijing, China
| | - Huanqin Wang
- Department of Viral Encephalitis, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention (IVDC, China CDC), Beijing, China
| | - Jiandong Li
- State Key Laboratory for Infectious Disease Prevention and Control (SKLID), Department of Viral Hemorrhagic Fever (IVDC, China CDC), Beijing, China
| | - Quanfu Zhang
- State Key Laboratory for Infectious Disease Prevention and Control (SKLID), Department of Viral Hemorrhagic Fever (IVDC, China CDC), Beijing, China
| | - Ying He
- Department of Viral Encephalitis, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention (IVDC, China CDC), Beijing, China
| | - Jia Li
- Department of Viral Encephalitis, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention (IVDC, China CDC), Beijing, China
| | - Juanjuan Fu
- Department of Viral Encephalitis, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention (IVDC, China CDC), Beijing, China
| | - Dexin Li
- State Key Laboratory for Infectious Disease Prevention and Control (SKLID), Department of Viral Hemorrhagic Fever (IVDC, China CDC), Beijing, China
| | - Guodong Liang
- Department of Viral Encephalitis, Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention (IVDC, China CDC), Beijing, China
- * E-mail:
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Lu WW, Sun JR, Wu SS, Lin WH, Kung SH. A dual reporter cell assay for identifying serotype and drug susceptibility of herpes simplex virus. Anal Biochem 2011; 415:97-104. [PMID: 21549682 DOI: 10.1016/j.ab.2011.04.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 04/03/2011] [Accepted: 04/12/2011] [Indexed: 10/18/2022]
Abstract
A dual reporter cell assay (DRCA) that allows real-time detection of herpes simplex virus (HSV) infection was developed. This was achieved by stable transfection of cells with an expression cassette that contains the dual reporter genes, secreted alkaline phosphatase (SEAP) and enhanced green fluorescent protein (EGFP), under the control of an HSV early gene promoter. Baby hamster kidney (BHK) and Chinese hamster ovary (CHO) cell lines were used as parental cell lines because the former is permissive for both HSV serotypes, HSV-1 and HSV-2, whereas the latter is susceptible to infection only by HSV-2. The DRCA permitted differential detection of HSV-1 and HSV-2 by observation of EGFP-positive cells, as substantiated by screening a total of 35 samples. The BHK-based cell line is sensitive to a viral titer as low as a single plaque-forming unit with a robust assay window as measured by a chemiluminescent assay. Evaluations of the DRCA with representative acyclovir-sensitive and acyclovir-resistant HSV strains demonstrated that their drug susceptibilities were accurately determined by a 48-h format. In summary, this novel DRCA is a useful means for serotyping of HSV in real time as well as a rapid screening method for determining anti-HSV susceptibilities.
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Affiliation(s)
- Wen-Wen Lu
- Department of Clinical Pathology, Cheng Hsin General Hospital, Taipei, Taiwan, China
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Tong L, Lin L, Zhao W, Wang B, Wu S, Liu H, Zhong X, Cui Y, Gu H, Zhang F, Zhong Z. Destabilization of coxsackievirus b3 genome integrated with enhanced green fluorescent protein gene. Intervirology 2011; 54:268-75. [PMID: 21242657 DOI: 10.1159/000321351] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Accepted: 09/14/2010] [Indexed: 11/19/2022] Open
Abstract
AIMS To evaluate the stability of coxsackievirus B (CVB) genome integrated with the enhanced green fluorescent protein gene (egfp) and provide valuable information for the use of the recombinant CVB variant. METHODS A CVB3 variant expressing eGFP was constructed by insertion of the egfp open-reading frame (ORF) at the 5' end of CVB3 ORF. The recombinant virus CVB3-eGFP was serially passaged in HeLa cells. The deletions in the CVB3-eGFP genome around egfp were examined by reverse transcription polymerase chain reaction and sequencing. RESULTS Genomic deletions of CVB3-eGFP could be observed as early as the 2nd passage. Sequencing showed that the genomic deletions caused either viral ORF shifts or partial deletions of the viral VP4 coding sequence. The 6th passage of CVB3-eGFP was checked by plaque assay for eGFP expression. All plaque-like foci showed eGFP expression. eGFP expression was also viewed in HeLa cells infected with plaque-forming viruses. CONCLUSIONS The insertion of egfp destabilized the CVB3 genome. The genomic deletions led to lethal mutations because of the termination of viral protein synthesis due to viral ORF shift and loss of partial viral gene. These findings imply that experimental data based on CVB integrated with the reporter gene should be interpreted with caution.
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Affiliation(s)
- Lei Tong
- Department of Microbiology, Harbin Medical University, China
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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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She RC, Preobrazhensky SN, Taggart EW, Petti CA, Bahler DW. Flow cytometric detection and serotyping of enterovirus for the clinical laboratory. J Virol Methods 2009; 162:245-50. [PMID: 19733594 PMCID: PMC7172270 DOI: 10.1016/j.jviromet.2009.08.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Revised: 08/24/2009] [Accepted: 08/27/2009] [Indexed: 11/20/2022]
Abstract
Culture and serotyping of human enteroviruses by fluorescence microscopy are time-consuming and labor-intensive. Flow cytometry has the potential of being more rapid, sensitive, and objective but has not been used for these purposes in a clinical laboratory. Primary rhesus monkey kidney (PMK) cells were inoculated with several enterovirus serotypes and stained with enterovirus-specific antibodies for flow cytometry and indirect fluorescence antibody testing (IFA). Kinetic studies of coxsackievirus B1 and echovirus 30 infection of PMK cells were performed on days 1–4 after inoculation. Flow cytometry results for echovirus 6, 9, 11, and 30 and coxsackievirus B1 correlated with IFA in all cases. Coxsackievirus B1 and echovirus 30 infections were detected 1 day earlier by flow cytometry than IFA. Flow cytometry can be effectively used for detecting enterovirus-infected cells in a clinical laboratory with the advantages of better quantitation of low levels of infection and earlier detection of virally infected cells in culture systems.
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Affiliation(s)
- Rosemary C She
- Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT, USA.
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Ghukasyan V, Hsu YY, Kung SH, Kao FJ. Application of fluorescence resonance energy transfer resolved by fluorescence lifetime imaging microscopy for the detection of enterovirus 71 infection in cells. JOURNAL OF BIOMEDICAL OPTICS 2007; 12:024016. [PMID: 17477731 DOI: 10.1117/1.2718582] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Timely and effective virus infection detection is critical for the clinical management and prevention of the disease spread in communities during an outbreak. A range of methods have been developed for this purpose, of which classical serological and viral nucleic acids detection are the most popular. We describe an alternative, imaging-based approach that utilizes fluorescence resonance energy transfer (FRET) resolved by fluorescence lifetime imaging microscopy (FLIM) and demonstrate it on the example of enterovirus 71 (EV71) infection detection. A plasmid construct is developed with the sequence for GFP2 and DsRed2 fluorescent proteins, linked by a 12-amino-acid-long cleavage recognition site for the 2A protease (2A(pro)), encoded by the EV71 genome and specific for the members of Picornaviridae family. In the construct expressed in HeLa cells, the linker binds the fluorophores within the Forster distance and creates a condition for FRET to occur, thus resulting in shortening of the GFP2 fluorescence lifetime. On cells infection with EV71, viral 2A(pro) released to the cytoplasm cleaves the recognition site, causing disruption of FRET through separation of the fluorophores. Thus, increased GFP2 lifetime to the native values, manifested by the time-correlated single-photon counting, serves as an efficient and specific indicator of the EV71 virus infection.
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Affiliation(s)
- Vladimir Ghukasyan
- National Yang-Ming University, Institute of Biophotonics Engineering, 155, Li-Nong St., Sec. 2, Taipei 112, Taiwan
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Hwang YC, Chen W, Yates MV. Use of fluorescence resonance energy transfer for rapid detection of enteroviral infection in vivo. Appl Environ Microbiol 2006; 72:3710-5. [PMID: 16672521 PMCID: PMC1472337 DOI: 10.1128/aem.72.5.3710-3715.2006] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteroviruses can be easily transmitted through the fecal-oral route and cause a diverse array of clinical manifestations. Recent outbreaks associated with enteroviral contamination in aquatic environments have called for the development of a more efficient and accurate virus monitoring system. To develop a simple, rapid, and direct method for identifying enteroviral infections, we generated a fluorescent reporter system in which genetically engineered cells express a hybrid fluorescent indicator composed of a linker peptide, which is exclusively cleaved by the 2A protease (2A(pro)), flanked with a cyan fluorescent protein (CFP) and a yellow fluorescent protein undergoing fluorescence resonance energy transfer. The covalent linkage between two fluorophores is disrupted due to 2A(pro) activity upon viral infection, which results in an increase in CFP intensity. This allows the rapid (within 7.5 h) detection of very low numbers (10 PFU or fewer) of infectious enteroviruses.
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Affiliation(s)
- Yu-Chen Hwang
- Department of Environmental Sciences, University of California, Riverside, CA 92521, USA
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Wang YC, Kao CL, Liu WT, Sun JR, Tai YE, Kung SH. A cell line that secretes inducibly a reporter protein for monitoring herpes simplex virus infection and drug susceptibility. J Med Virol 2002; 68:599-605. [PMID: 12376969 DOI: 10.1002/jmv.10230] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A cell line modified genetically (Vero-ICP10-SEAP) that responds to infection by herpes simplex virus (HSV) was established. The cell line was constructed by stable transfection of Vero cell with a plasmid encoding the secreted alkaline phosphatase (SEAP) driven by the promoter of the HSV-2 ICP10 gene. Following infection with HSV, the stable line secretes a high level of the SEAP in the supernatants as measured by a chemiluminescence-based assay. The detection system is sensitive to an HSV titer as low as a single plaque-forming unit (PFU), with a linear range up to the equivalent of 2.5 x 10(4) PFU inoculum after infection for 24 h. There was no detectable enhancement in SEAP activities following inoculations with several viruses other than HSV. The Vero-ICP10-SEAP cell line was also utilized to develop an assay for determination of antiviral susceptibility given that the induced SEAP activity appeared to reflect the numbers of plaque. Evaluations of the stable line with representative acyclovir (ACV)-sensitive and-resistant HSV isolates demonstrated that their drug susceptibilities were determined accurately. In summary, this novel SEAP reporter system is a sensitive means for rapid diagnosis, quantitation, and drug susceptibility testing for HSV, with potential to the development of an automated assay.
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Affiliation(s)
- Yu-Chun Wang
- Faculty of Medical Technology and Institute of Biotechnology in Medicine, National Yang-Ming University, Shih-Pai, 112, Taipei, Taiwan, ROC
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Liu WT, Sun JR, Lin CH, Kuo RL, Kung SH. An indicator cell assay for detection of human cytomegalovirus based on enhanced green fluorescent protein. J Virol Methods 2001; 96:85-92. [PMID: 11516491 DOI: 10.1016/s0166-0934(01)00320-2] [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: 11/16/2022]
Abstract
An indicator cell line (ML-UL54-EGFP) for the detection of human cytomegalovirus (HCMV) by a simple and direct method was developed. The stable line was constructed by introducing into mink lung cells an expression cassette that contains the enhanced green fluorescent protein (EGFP) reporter gene under the control of an HCMV-inducible promoter. The promoter was from the upstream region of the HCMV UL54 (pol) gene, an early gene promoter that is activated in the early phase of HCMV infection. Following infection with HCMV for 48 h, the stable line expressed well detectable level of the EGFP as observed under a fluorescence microscope. The sensitivity of the indicator cell assay is at least comparable with that of a plaque assay as assessed with a panel of HCMV strains. There were no detectable fluorescent cells after inoculations with several viruses other than HCMV, indicating high specificity. Analysis with flow cytometry revealed that the induced fluorescence from the infected cells was proportional to the titer of HCMV inoculated, making it possible to quantify HCMV infectious particles. In summary, the EGFP-based indicator cell line is of potential use for rapid detection and quantification of HCMV in clinical specimens.
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Affiliation(s)
- W T Liu
- Faculty of Medical Technology and Institute of Biotechnology in Medicine, National Yang-Ming University, Shih-Pai, 112, Taipei, Taiwan, ROC
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