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St Clair LA, Chan LLY, Boretsky A, Lin B, Spedding M, Perera R. High-Throughput SARS-CoV-2 Antiviral Testing Method Using the Celigo Image Cytometer. J Fluoresc 2024; 34:561-570. [PMID: 37310590 PMCID: PMC10261830 DOI: 10.1007/s10895-023-03289-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 05/27/2023] [Indexed: 06/14/2023]
Abstract
The COVID-19 pandemic has created a worldwide public health crisis that has since resulted in 6.8 million reported deaths. The pandemic prompted the immediate response of researchers around the world to engage in rapid vaccine development, surveillance programs, and antiviral testing, which resulted in the delivery of multiple vaccines and repurposed antiviral drug candidates. However, the emergence of new highly transmissible SARS-CoV-2 variants has renewed the desire for discovering new antiviral drug candidates with high efficacy against the emerging variants of concern. Traditional antiviral testing methods employ the plaque-reduction neutralization tests (PRNTs), plaque assays, or RT-PCR analysis, but each assay can be tedious and time-consuming, requiring 2-3 days to complete the initial antiviral assay in biologically relevant cells, and then 3-4 days to visualize and count plaques in Vero cells, or to complete cell extractions and PCR analysis. In recent years, plate-based image cytometers have demonstrated high-throughput vaccine screening methods, which can be adopted for screening potential antiviral drug candidates. In this work, we developed a high-throughput antiviral testing method employing the Celigo Image Cytometer to investigate the efficacy of antiviral drug candidates on SARS-CoV-2 infectivity using a fluorescent reporter virus and their safety by measuring the cytotoxicity effects on the healthy host cell line using fluorescent viability stains. Compared to traditional methods, the assays defined here eliminated on average 3-4 days from our standard processing time for antiviral testing. Moreover, we were able to utilize human cell lines directly that are not typically amenable to PRNT or plaque assays. The Celigo Image Cytometer can provide an efficient and robust method to rapidly identify potential antiviral drugs to effectively combat the rapidly spreading SARS-CoV-2 virus and its variants during the pandemic.
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Affiliation(s)
- Laura A St Clair
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology, and Pathology, Colorado State University, CO, 80523, Fort Collins, USA
- Center for Metabolism of Infectious Diseases (C4MInD), Colorado State University, 3185 Rampart Rd, Fort Collins, CO, 80523, USA
| | - Leo Li-Ying Chan
- Department of Advanced Technology R&D, Revvity, 360 Merrimack St. Suite 200, Lawrence, MA, 01843, USA.
| | - Adam Boretsky
- Department of Advanced Technology R&D, Revvity, 360 Merrimack St. Suite 200, Lawrence, MA, 01843, USA
| | - Bo Lin
- Department of Advanced Technology R&D, Revvity, 360 Merrimack St. Suite 200, Lawrence, MA, 01843, USA
| | | | - Rushika Perera
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology, and Pathology, Colorado State University, CO, 80523, Fort Collins, USA.
- Center for Metabolism of Infectious Diseases (C4MInD), Colorado State University, 3185 Rampart Rd, Fort Collins, CO, 80523, USA.
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2
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Kapoor V, Briese T, Ranjan A, Donovan WM, Mansukhani MM, Chowdhary R, Lipkin WI. Validation of the VirCapSeq-VERT system for differential diagnosis, detection, and surveillance of viral infections. J Clin Microbiol 2024; 62:e0061223. [PMID: 38095845 PMCID: PMC10793283 DOI: 10.1128/jcm.00612-23] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 11/06/2023] [Indexed: 01/18/2024] Open
Abstract
IMPORTANCE Broad range assay for accurate and sensitive diagnostics.
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Affiliation(s)
- Vishal Kapoor
- Center for Infection and Immunity, Mailman School of Public Health, Columbia University, New York, New York, USA
- Rabindranath Tagore University, Bhopal, India
| | - Thomas Briese
- Center for Infection and Immunity, Mailman School of Public Health, Columbia University, New York, New York, USA
- Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, USA
| | - Amit Ranjan
- Center for Infection and Immunity, Mailman School of Public Health, Columbia University, New York, New York, USA
| | - William M. Donovan
- Center for Infection and Immunity, Mailman School of Public Health, Columbia University, New York, New York, USA
| | - Mahesh M. Mansukhani
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons,Columbia University, New York, New York, USA
| | | | - W. Ian Lipkin
- Center for Infection and Immunity, Mailman School of Public Health, Columbia University, New York, New York, USA
- Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, USA
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons,Columbia University, New York, New York, USA
- Department of Neurology, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York, USA
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3
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Simões M, da Silva SA, Lúcio KA, de Oliveira Vieira R, Schwarcz WD, de Lima SMB, Camacho LAB. Standardization, validation, and comparative evaluation of a faster and high-performance test for quantification of yellow fever neutralizing antibodies. J Immunol Methods 2023; 522:113568. [PMID: 37748728 DOI: 10.1016/j.jim.2023.113568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 06/06/2023] [Accepted: 09/21/2023] [Indexed: 09/27/2023]
Abstract
Although it is considered the reference for quantification of neutralizing antibodies, classical method of the plaque reduction neutralization test (PRNT) is labor intensive, requires specific equipment and inputs, besides a long time for its finalization, even in the micro-PRNT version (in 96-well plates). It has a higher sample throughput, however the smaller wells make the reading of plaques more difficult. With an immunoenzymatic revelation step and a semi-automated reading, the μFRN-HRP (micro Focus Reduction Neutralization - Horseradish Peroxidase) is a faster and more efficient test for the quantification of YF neutralizing antibodies. This study aimed to standardize, validate, and compare it with the reference method in 6-well plates (PRNT). Once the execution protocol was standardized, precision, accuracy, selectivity, and robustness were evaluated to validate the μFRN-HRP. In addition, 200 sera of vaccinees were processed by the μFRN-HRP and by the micro-PRNT to compare with the reference test, estimating agreement by Intraclass Correlation Coefficient (ICC). The standardization and validation of the μFRN-HRP was carried out successfully. Weak to moderate agreement was observed between μFRN-HRP and PRNT for titers in reciprocal dilution, while the same comparison between the classical tests resulted in a better ICC. However, titers in milli-international units obtained by μFRN-HRP showed a substantial agreement with PRNT, while the agreement between micro-PRNT and PRNT was inferior. Therefore, μFRN-HRP can be used in the confirmation of natural YF infection and immune response to vaccination, replacing the micro-PRNT, gaining agility, while preserving the specificity of the result.
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Affiliation(s)
- Marisol Simões
- Laboratório de Tecnologia Virológica, Instituto de Tecnologia em Imunobiológicos, Fiocruz, Rio de Janeiro, RJ, Brazil.
| | - Stephanie Almeida da Silva
- Laboratório de Tecnologia Virológica, Instituto de Tecnologia em Imunobiológicos, Fiocruz, Rio de Janeiro, RJ, Brazil
| | - Kelly Araújo Lúcio
- Laboratório de Tecnologia Virológica, Instituto de Tecnologia em Imunobiológicos, Fiocruz, Rio de Janeiro, RJ, Brazil
| | - Renan de Oliveira Vieira
- Laboratório de Tecnologia Virológica, Instituto de Tecnologia em Imunobiológicos, Fiocruz, Rio de Janeiro, RJ, Brazil
| | - Waleska Dias Schwarcz
- Laboratório de Tecnologia Virológica, Instituto de Tecnologia em Imunobiológicos, Fiocruz, Rio de Janeiro, RJ, Brazil
| | - Sheila Maria Barbosa de Lima
- Laboratório de Tecnologia Virológica, Instituto de Tecnologia em Imunobiológicos, Fiocruz, Rio de Janeiro, RJ, Brazil
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4
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Dodkins R, Delaney JR, Overton T, Scholle F, Frias-De-Diego A, Crisci E, Huq N, Jordan I, Kimata JT, Findley T, Goldberg IG. A rapid, high-throughput, viral infectivity assay using automated brightfield microscopy with machine learning. SLAS Technol 2023; 28:324-333. [PMID: 37451651 DOI: 10.1016/j.slast.2023.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 07/06/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
Infectivity assays are essential for the development of viral vaccines, antiviral therapies, and the manufacture of biologicals. Traditionally, these assays take 2-7 days and require several manual processing steps after infection. We describe an automated viral infectivity assay (AVIATM), using convolutional neural networks (CNNs) and high-throughput brightfield microscopy on 96-well plates that can quantify infection phenotypes within hours, before they are manually visible, and without sample preparation. CNN models were trained on HIV, influenza A virus, coronavirus 229E, vaccinia viruses, poliovirus, and adenoviruses, which together span the four major categories of virus (DNA, RNA, enveloped, and non-enveloped). A sigmoidal function, fit between virus dilution curves and CNN predictions, results in sensitivity ranges comparable to or better than conventional plaque or TCID50 assays, and a precision of ∼10%, which is considerably better than conventional infectivity assays. Because this technology is based on sensitizing CNNs to specific phenotypes of infection, it has potential as a rapid, broad-spectrum tool for virus characterization, and potentially identification.
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Affiliation(s)
| | | | - Tess Overton
- Department of Biological Sciences North Carolina State University Raleigh, NC 27695, United States
| | - Frank Scholle
- Department of Biological Sciences North Carolina State University Raleigh, NC 27695, United States
| | - Alba Frias-De-Diego
- College of Veterinary Medicine, Department of Population Health and Pathobiology, North Carolina State University, Raleigh, NC 27695, United States
| | - Elisa Crisci
- College of Veterinary Medicine, Department of Population Health and Pathobiology, North Carolina State University, Raleigh, NC 27695, United States
| | - Nafisa Huq
- Melbec Microbiology Ltd, Rossendale, Lancashire, BB4 4QJ, United Kingdom
| | - Ingo Jordan
- ProBioGen AG, Goethestr. 54, 13086 Berlin, Germany
| | - Jason T Kimata
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, United States
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5
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Liu T, Li Y, Koydemir HC, Zhang Y, Yang E, Eryilmaz M, Wang H, Li J, Bai B, Ma G, Ozcan A. Rapid and stain-free quantification of viral plaque via lens-free holography and deep learning. Nat Biomed Eng 2023; 7:1040-1052. [PMID: 37349390 PMCID: PMC10427422 DOI: 10.1038/s41551-023-01057-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 05/14/2023] [Indexed: 06/24/2023]
Abstract
A plaque assay-the gold-standard method for measuring the concentration of replication-competent lytic virions-requires staining and usually more than 48 h of runtime. Here we show that lens-free holographic imaging and deep learning can be combined to expedite and automate the assay. The compact imaging device captures phase information label-free at a rate of approximately 0.32 gigapixels per hour per well, covers an area of about 30 × 30 mm2 and a 10-fold larger dynamic range of virus concentration than standard assays, and quantifies the infected area and the number of plaque-forming units. For the vesicular stomatitis virus, the automated plaque assay detected the first cell-lysing events caused by viral replication as early as 5 h after incubation, and in less than 20 h it detected plaque-forming units at rates higher than 90% at 100% specificity. Furthermore, it reduced the incubation time of the herpes simplex virus type 1 by about 48 h and that of the encephalomyocarditis virus by about 20 h. The stain-free assay should be amenable for use in virology research, vaccine development and clinical diagnosis.
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Affiliation(s)
- Tairan Liu
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- Bioengineering Department, University of California, Los Angeles, USA
- California NanoSystems Institute (CNSI), University of California, Los Angeles, CA, USA
| | - Yuzhu Li
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- Bioengineering Department, University of California, Los Angeles, USA
- California NanoSystems Institute (CNSI), University of California, Los Angeles, CA, USA
| | - Hatice Ceylan Koydemir
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
- Center for Remote Health Technologies and Systems, Texas A&M University, College Station, TX, USA
| | - Yijie Zhang
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- Bioengineering Department, University of California, Los Angeles, USA
- California NanoSystems Institute (CNSI), University of California, Los Angeles, CA, USA
| | - Ethan Yang
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- Department of Mathematics, University of California, Los Angeles, CA, USA
| | - Merve Eryilmaz
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- Bioengineering Department, University of California, Los Angeles, USA
| | - Hongda Wang
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- Bioengineering Department, University of California, Los Angeles, USA
- California NanoSystems Institute (CNSI), University of California, Los Angeles, CA, USA
| | - Jingxi Li
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- Bioengineering Department, University of California, Los Angeles, USA
- California NanoSystems Institute (CNSI), University of California, Los Angeles, CA, USA
| | - Bijie Bai
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- Bioengineering Department, University of California, Los Angeles, USA
- California NanoSystems Institute (CNSI), University of California, Los Angeles, CA, USA
| | - Guangdong Ma
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA
- School of Physics, Xi'an Jiaotong University, Xi'an, China
| | - Aydogan Ozcan
- Electrical and Computer Engineering Department, University of California, Los Angeles, CA, USA.
- Bioengineering Department, University of California, Los Angeles, USA.
- California NanoSystems Institute (CNSI), University of California, Los Angeles, CA, USA.
- Department of Surgery, University of California, Los Angeles, CA, USA.
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6
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Hochdorfer D, Businger R, Hotter D, Seifried C, Solzin J. Automated, label-free TCID 50 assay to determine the infectious titer of virus-based therapeutics. J Virol Methods 2021; 299:114318. [PMID: 34626683 DOI: 10.1016/j.jviromet.2021.114318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 10/05/2021] [Accepted: 10/05/2021] [Indexed: 01/09/2023]
Abstract
A robust and precise infectivity assay is a prerequisite for the development and market supply of virus-based biologics. Like other cell-based assays, traditional infectivity assays suffer from high variability and require extensive hands-on time. Therefore, a faster and more robust method to measure infectivity is needed to fulfill the requirements of a higher sample throughput and speed in drug development. We developed a label-free tissue culture infectious dose 50 (TCID50) assay using automated image analysis that determines the cell confluence to discriminate between cytopathic effect-positive and -negative wells. In addition, we implemented semi-automated bench-top pipetting robots for the required pipetting steps to further shorten the hands-on time of the assay. The automated image analysis categorized >99 % of the wells similar as operators did via visual evaluation and there was a close correlation between the titers that were determined by using either the automated image analysis or visual evaluation (r² = 0.99). Thus, here we present a label-free TCID50 method with a stable automated image analysis that is ∼3.6x faster and more standardized compared to the classical TCID50 assay.
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Affiliation(s)
- Daniel Hochdorfer
- Boehringer Ingelheim GmbH & Co. KG, Innovation Unit, Analytical Development Biologicals, Biberach, Germany
| | - Ramona Businger
- Boehringer Ingelheim GmbH & Co. KG, Innovation Unit, Analytical Development Biologicals, Biberach, Germany
| | - Dominik Hotter
- Boehringer Ingelheim GmbH & Co. KG, Innovation Unit, Analytical Development Biologicals, Biberach, Germany
| | - Carina Seifried
- Boehringer Ingelheim GmbH & Co. KG, Innovation Unit, Analytical Development Biologicals, Biberach, Germany
| | - Johannes Solzin
- Boehringer Ingelheim GmbH & Co. KG, Innovation Unit, Analytical Development Biologicals, Biberach, Germany.
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An X, Martinez-Paniagua M, Rezvan A, Sefat SR, Fathi M, Singh S, Biswas S, Pourpak M, Yee C, Liu X, Varadarajan N. Single-dose intranasal vaccination elicits systemic and mucosal immunity against SARS-CoV-2. iScience 2021; 24:103037. [PMID: 34462731 PMCID: PMC8388188 DOI: 10.1016/j.isci.2021.103037] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 05/21/2021] [Accepted: 08/23/2021] [Indexed: 12/18/2022] Open
Abstract
Despite remarkable progress in the development and authorization of vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there is a need to validate vaccine platforms for broader application. The current intramuscular vaccines are designed to elicit systemic immunity without conferring mucosal immunity in the nasal compartment, which is the first barrier that SARS-CoV-2 virus breaches before dissemination to the lung. We report the development of an intranasal subunit vaccine that uses lyophilized spike protein and liposomal STING agonist as an adjuvant. This vaccine induces systemic neutralizing antibodies, IgA in the lung and nasal compartments, and T-cell responses in the lung of mice. Single-cell RNA sequencing confirmed the coordinated activation of T/B-cell responses in a germinal center-like manner within the nasal-associated lymphoid tissues, confirming its role as an inductive site to enable durable immunity. The ability to elicit immunity in the respiratory tract can prevent the establishment of infection in individuals and prevent disease transmission.
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Affiliation(s)
- Xingyue An
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204, USA
| | - Melisa Martinez-Paniagua
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204, USA
| | - Ali Rezvan
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204, USA
| | - Samiur Rahman Sefat
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204, USA
| | - Mohsen Fathi
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204, USA
| | - Shailbala Singh
- Department of Melanoma Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Sujit Biswas
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, USA
| | | | - Cassian Yee
- Department of Melanoma Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA
| | - Xinli Liu
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX 77204, USA
| | - Navin Varadarajan
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204, USA
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Ye M, Keicher M, Gentschev I, Szalay AA. Efficient Selection of Recombinant Fluorescent Vaccinia Virus Strains and Rapid Virus Titer Determination by Using a Multi-Well Plate Imaging System. Biomedicines 2021; 9:biomedicines9081032. [PMID: 34440236 PMCID: PMC8393244 DOI: 10.3390/biomedicines9081032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/12/2021] [Accepted: 08/12/2021] [Indexed: 12/17/2022] Open
Abstract
Engineered vaccinia virus (VACV) strains are used extensively as vectors for the development of novel cancer vaccines and cancer therapeutics. In this study, we describe for the first time a high-throughput approach for both fluorescent rVACV generation and rapid viral titer measurement with the multi-well plate imaging system, IncuCyte®S3. The isolation of a single, well-defined plaque is critical for the generation of novel recombinant vaccinia virus (rVACV) strains. Unfortunately, current methods of rVACV engineering via plaque isolation are time-consuming and laborious. Here, we present a modified fluorescent viral plaque screening and selection strategy that allows one to generally obtain novel fluorescent rVACV strains in six days, with a minimum of just four days. The standard plaque assay requires chemicals for fixing and staining cells. Manual plaque counting based on visual inspection of the cell culture plates is time-consuming. Here, we developed a fluorescence-based plaque assay for quantifying the vaccinia virus that does not require a cell staining step. This approach is less toxic to researchers and is reproducible; it is thus an improvement over the traditional assay. Lastly, plaque counting by virtue of a fluorescence-based image is very convenient, as it can be performed directly on the computer.
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Affiliation(s)
- Mingyu Ye
- Department of Biochemistry and Cancer Therapy Research Center (CTRC), Biocenter, University of Wuerzburg, Theodor-Boveri-Weg 1, 97074 Wuerzburg, Germany; (M.K.); (I.G.)
- Correspondence: (M.Y.); (A.A.S.); Tel.:+49-931-3189187 (M.Y.); +49-931-3184410 (A.A.S.)
| | - Markus Keicher
- Department of Biochemistry and Cancer Therapy Research Center (CTRC), Biocenter, University of Wuerzburg, Theodor-Boveri-Weg 1, 97074 Wuerzburg, Germany; (M.K.); (I.G.)
| | - Ivaylo Gentschev
- Department of Biochemistry and Cancer Therapy Research Center (CTRC), Biocenter, University of Wuerzburg, Theodor-Boveri-Weg 1, 97074 Wuerzburg, Germany; (M.K.); (I.G.)
| | - Aladar A. Szalay
- Department of Biochemistry and Cancer Therapy Research Center (CTRC), Biocenter, University of Wuerzburg, Theodor-Boveri-Weg 1, 97074 Wuerzburg, Germany; (M.K.); (I.G.)
- Department of Radiation Oncology, Rebecca & John Moores Comprehensive Cancer Center, University of California, San Diego, CA 92093, USA
- Department of Pathology, Center of Immune Technologies, Stanford University School of Medicine, Stanford, CA 94305, USA
- Correspondence: (M.Y.); (A.A.S.); Tel.:+49-931-3189187 (M.Y.); +49-931-3184410 (A.A.S.)
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9
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Arias-Arias JL, Corrales-Aguilar E, Mora-Rodríguez RA. A Fluorescent Real-Time Plaque Assay Enables Single-Cell Analysis of Virus-Induced Cytopathic Effect by Live-Cell Imaging. Viruses 2021; 13:v13071193. [PMID: 34206483 PMCID: PMC8310316 DOI: 10.3390/v13071193] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 06/16/2021] [Accepted: 06/17/2021] [Indexed: 12/20/2022] Open
Abstract
Conventional plaque assays rely on the use of overlays to restrict viral infection allowing the formation of distinct foci that grow in time as the replication cycle continues leading to countable plaques that are visualized with standard techniques such as crystal violet, neutral red, or immunolabeling. This classical approach takes several days until large enough plaques can be visualized and counted with some variation due to subjectivity in plaque recognition. Since plaques are clonal lesions produced by virus-induced cytopathic effect, we applied DNA fluorescent dyes with differential cell permeability to visualize them by live-cell imaging. We could observe different stages of that cytopathic effect corresponding to an early wave of cells with chromatin-condensation followed by a wave of dead cells with membrane permeabilization within plaques generated by different animal viruses. This approach enables an automated plaque identification using image analysis to increase single plaque resolution compared to crystal violet counterstaining and allows its application to plaque tracking and plaque reduction assays to test compounds for both antiviral and cytotoxic activities. This fluorescent real-time plaque assay sums to those next-generation technologies by combining this robust classical method with modern fluorescence microscopy and image analysis approaches for future applications in virology.
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Affiliation(s)
- Jorge L. Arias-Arias
- Centro de Investigación en Enfermedades Tropicales (CIET), Facultad de Microbiología, Universidad de Costa Rica, San José 11501-2060, Costa Rica; (E.C.-A.); (R.A.M.-R.)
- Dulbecco Lab Studio, Residencial Lisboa 2G, Alajuela 20102, Costa Rica
- Correspondence:
| | - Eugenia Corrales-Aguilar
- Centro de Investigación en Enfermedades Tropicales (CIET), Facultad de Microbiología, Universidad de Costa Rica, San José 11501-2060, Costa Rica; (E.C.-A.); (R.A.M.-R.)
| | - Rodrigo A. Mora-Rodríguez
- Centro de Investigación en Enfermedades Tropicales (CIET), Facultad de Microbiología, Universidad de Costa Rica, San José 11501-2060, Costa Rica; (E.C.-A.); (R.A.M.-R.)
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10
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Pearson M, LaVoy A, Chan LLY, Dean GA. High-throughput viral microneutralization method for feline coronavirus using image cytometry. J Virol Methods 2020; 286:113979. [PMID: 32979406 PMCID: PMC7510446 DOI: 10.1016/j.jviromet.2020.113979] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/12/2020] [Accepted: 09/19/2020] [Indexed: 01/24/2023]
Abstract
There are no approved antiviral drugs or recommended vaccines for feline coronavirus infection. Plate-based image cytometry is used for high-throughput viral microneutralization assays. Image cytometry is faster and more sensitive than traditional plaque reduction neutralization tests. Cell seeding density, plate surface coating, virus concentration and incubation time, fluorescent labeling, and buffers were optimized. Cross-neutralization between FCoV type I and II viruses was not observed.
Feline coronaviruses (FCoV) are members of the alphacoronavirus genus that are further characterized by serotype (types I and II) based on the antigenicity of the spike (S) protein and by pathotype based on the associated clinical conditions. Feline enteric coronaviruses (FECV) are associated with the vast majority of infections and are typically asymptomatic. Within individual animals, FECV can mutate and cause a severe and usually fatal disease called feline infectious peritonitis (FIP), the leading infectious cause of death in domestic cat populations. There are no approved antiviral drugs or recommended vaccines to treat or prevent FCoV infection. The plaque reduction neutralization test (PRNT) traditionally employed to assess immune responses and to screen therapeutic and vaccine candidates is time-consuming, low-throughput, and typically requires 2–3 days for the formation and manual counting of cytolytic plaques. Host cells are capable of carrying heavy viral burden in the absence of visible cytolytic effects, thereby reducing the sensitivity of the assay. In addition, operator-to-operator variation can generate uncertainty in the results and digital records are not automatically created. To address these challenges we developed a novel high-throughput viral microneutralization assay, with quantification of virus-infected cells performed in a plate-based image cytometer. Host cell seeding density, microplate surface coating, virus concentration and incubation time, wash buffer and fluorescent labeling were optimized. Subsequently, this FCoV viral neutralization assay was used to explore immune correlates of protection using plasma from naturally FECV-infected cats. We demonstrate that the high-throughput viral neutralization assay using the Celigo Image Cytometer provides a robust and efficient method for the rapid screening of therapeutic antibodies, antiviral compounds, and vaccines. This method can be applied to various viral infectious diseases to accelerate vaccine and antiviral drug discovery and development.
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Affiliation(s)
- Morgan Pearson
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523, United States
| | - Alora LaVoy
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523, United States
| | - Leo Li-Ying Chan
- Department of Advanced Technology R&D, Nexcelom Bioscience LLC, Lawrence, MA, 01843, United States.
| | - Gregg A Dean
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, 80523, United States
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An X, Martinez-Paniagua M, Rezvan A, Fathi M, Singh S, Biswas S, Pourpak M, Yee C, Liu X, Varadarajan N. Single-dose intranasal vaccination elicits systemic and mucosal immunity against SARS-CoV-2. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020. [PMID: 32743568 DOI: 10.1101/2020.07.23.212357] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A safe and durable vaccine is urgently needed to tackle the COVID19 pandemic that has infected >15 million people and caused >620,000 deaths worldwide. As with other respiratory pathogens, the nasal compartment is the first barrier that needs to be breached by the SARS-CoV-2 virus before dissemination to the lung. Despite progress at remarkable speed, current intramuscular vaccines are designed to elicit systemic immunity without conferring mucosal immunity. We report the development of an intranasal subunit vaccine that contains the trimeric or monomeric spike protein and liposomal STING agonist as adjuvant. This vaccine induces systemic neutralizing antibodies, mucosal IgA responses in the lung and nasal compartments, and T-cell responses in the lung of mice. Single-cell RNA-sequencing confirmed the concomitant activation of T and B cell responses in a germinal center-like manner within the nasal-associated lymphoid tissues (NALT), confirming its role as an inductive site that can lead to long-lasting immunity. The ability to elicit immunity in the respiratory tract has can prevent the initial establishment of infection in individuals and prevent disease transmission across humans.
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