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Toft CJ, Stocks BB, Schaeffer PM. Comparison of the analytical sensitivity of COVID-19 rapid antigen tests in Australia and Canada. Talanta 2024; 275:126147. [PMID: 38677170 DOI: 10.1016/j.talanta.2024.126147] [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: 11/23/2023] [Revised: 04/18/2024] [Accepted: 04/22/2024] [Indexed: 04/29/2024]
Abstract
Rapid testing has become an indispensable strategy to identify the most infectious individuals and prevent the transmission of SARS-CoV-2 in vulnerable populations. As such, COVID-19 rapid antigen tests (RATs) are being manufactured faster than ever yet lack relevant comparative analyses required to inform on absolute analytical sensitivity and performance, limiting end-user ability to accurately compare brands for decision making. To date, more than 1000 different COVID-19 RATs are commercially available in the world, most of which detect the viral nucleocapsid protein (NP). Here, we examine and compare the analytical sensitivity of 26 RATs that are readily available in Canada and/or Australia using two NP reference materials (RMs) - a fluorescent NP-GFP expressed in bacterial cells and NCAP-1 produced in a mammalian expression system. Both RMs generate highly comparable results within each RAT, indicating minimal bias due to differing expression systems and final buffer compositions. However, we demonstrate orders of magnitude differences in analytical sensitivities among distinct RATs, and find little correlation with the median tissue culture infectious dose (TCID50) assay values reported by manufacturers. In addition, two COVID-19/Influenza A&B combination RATs were evaluated with influenza A NP-GFP. Finally, important logistics considerations are discussed regarding the robustness, ease of international shipping and safe use of these reference proteins. Taken together, our data highlight the need for and practicality of readily available, reliable reference proteins for end-users that will ensure that manufacturers maintain batch-to-batch quality and accuracy of RATs. They will aid international public health and government agencies, as well as health and aged care facilities to reliably benchmark and select the best RATs to curb transmission of future SARS-CoV-2 and influenza outbreaks.
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Affiliation(s)
- Casey J Toft
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Douglas, Queensland, Australia
| | - Bradley B Stocks
- Metrology, National Research Council Canada, 1200 Montreal Road, Ottawa, Ontario, K1A 0R6, Canada.
| | - Patrick M Schaeffer
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Douglas, Queensland, Australia.
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Kakimoto M, Nomura T, Nazmul T, Yamamoto A, Sasaki H, Higashiura A, Ito M, Ohge H, Mikage M, Ogawa KO, Sakaguchi T. In vitro anti-severe acute respiratory syndrome coronavirus 2 effect of Ephedra przewalskii Stapf extract. JOURNAL OF ETHNOPHARMACOLOGY 2024; 319:117341. [PMID: 37879507 DOI: 10.1016/j.jep.2023.117341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 10/20/2023] [Accepted: 10/21/2023] [Indexed: 10/27/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The terrestrial stems of Ephedra (Ephedra spp.; including Ephedra sinica Stapf and Ephedra przewalskii Stapf) extracts are used in traditional medicines in East Asia. In Japan, the Kampo formula containing E. sinica extract is prescribed for the treatment of the common cold, influenza virus infections, and mild symptoms of coronavirus disease 2019 (COVID-19). Although ephedrine alkaloids in E. sinica exert antitussive effects, they may have side effects associated with the sympathetic nervous system. E. przewalskii extract, a drug used in traditional Uyghur and Mongolian medicine, is considered to be free of ephedrine alkaloids and is a promising candidate for the treatment of infectious diseases. However, its use is currently limited because evidence of its antiviral efficacy remains inconclusive. AIM OF THE STUDY We compared the anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) effects of E. przewalskii and E. sinica extracts in vitro. Additionally, we examined the differences in their antiviral effects against different SARS-CoV-2 strains. MATERIALS AND METHODS VeroE6/TMPRSS2 cells were infected with SARS-CoV-2 (Conventional, Delta, and Omicron strains-BA.1, BA.2, BA.4, and BA.5), and lysates prepared from each herbal extract were added. The infectious titer was determined using the 50% tissue culture infectious dose (TCID50) method; in turn, the half-maximal inhibitory concentration (IC50) was calculated for each extract to compare the antiviral efficacy of E. sinica and E. przewalskii extracts. Further, the extracts were compared with remdesivir for their antiviral efficacy against the conventional viral strain. To verify the effect of the inactivation of virus particles, these extracts were added to each SARS-CoV-2 strain, and the infectious titers were determined using the TCID50 method. RESULTS The antiviral efficacy (i.e., IC50) of the E. przewalskii extract against each SARS-CoV-2 strain was 2.7-10.8-fold greater than that of the E. sinica extract. The antiviral efficacy of the E. przewalskii extract against conventional viral strains was compared with that of remdesivir, which was 1/27.6 of remdesivir's efficacy. The E. sinica extract showed minimal inactivation of virus particles of each strain, whereas the E. przewalskii extract resulted in substantial viral inactivation. CONCLUSIONS The E. przewalskii extract showed higher antiviral activity against SARS-CoV-2 than the E. sinica extract. Overall, our study suggests that E. przewalskii extract can be used for the treatment of viral infections, including COVID-19.
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Affiliation(s)
- Masaki Kakimoto
- Department of Community Based Medical System, School of Medicine, Hiroshima University, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan; Department of General Internal Medicine, Hiroshima University Hospital, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan.
| | - Toshihito Nomura
- Department of Infectious Diseases, Hiroshima University Hospital, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan; Department of Virology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan
| | - Tanuza Nazmul
- Department of Virology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan
| | - Akima Yamamoto
- Department of Virology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan
| | - Hiroaki Sasaki
- Department of Virology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan; Division of Health, First Service School, Japan Maritime Self Defense Force, Etajimacho Kokuyu-mubanchi, Etajima, 737-2195, Japan
| | - Akifumi Higashiura
- Department of Virology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan
| | - Masanori Ito
- Department of General Internal Medicine, Hiroshima University Hospital, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan
| | - Hiroki Ohge
- Department of Infectious Diseases, Hiroshima University Hospital, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan
| | - Masayuki Mikage
- Emeritus of Kanazawa University, Kakumamachi, Kanazawa, 920-1192, Japan
| | - Keiko Ochiai Ogawa
- Department of General Internal Medicine, Hiroshima University Hospital, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan; Department of Kampo Clinical Center, Hiroshima University Hospital, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan
| | - Takemasa Sakaguchi
- Department of Virology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minamiku, Hiroshima, 734-8551, Japan
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Zhou L, Vestri A, Marchesano V, Rippa M, Sagnelli D, Picazio G, Fusco G, Han J, Zhou J, Petti L. The Label-Free Detection and Identification of SARS-CoV-2 Using Surface-Enhanced Raman Spectroscopy and Principal Component Analysis. BIOSENSORS 2023; 13:1014. [PMID: 38131774 PMCID: PMC10741931 DOI: 10.3390/bios13121014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 11/24/2023] [Accepted: 12/03/2023] [Indexed: 12/23/2023]
Abstract
The World Health Organization (WHO) declared in a May 2023 announcement that the COVID-19 illness is no longer categorized as a Public Health Emergency of International Concern (PHEIC); nevertheless, it is still considered an actual threat to world health, social welfare and economic stability. Consequently, the development of a convenient, reliable and affordable approach for detecting and identifying SARS-CoV-2 and its emerging new variants is crucial. The fingerprint and signal amplification characteristics of surface-enhanced Raman spectroscopy (SERS) could serve as an assay scheme for SARS-CoV-2. Here, we report a machine learning-based label-free SERS technique for the rapid and accurate detection and identification of SARS-CoV-2. The SERS spectra collected from samples of four types of coronaviruses on gold nanoparticles film, fabricated using a Langmuir-Blodgett self-assembly, can provide more spectroscopic signatures of the viruses and exhibit low limits of detection (<100 TCID50/mL or even <10 TCID50/mL). Furthermore, the key Raman bands of the SERS spectra were systematically captured by principal component analysis (PCA), which effectively distinguished SARS-CoV-2 and its variant from other coronaviruses. These results demonstrate that the combined use of SERS technology and PCA analysis has great potential for the rapid analysis and discrimination of multiple viruses and even newly emerging viruses without the need for a virus-specific probe.
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Affiliation(s)
- Lu Zhou
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (L.Z.); (A.V.); (V.M.); (M.R.); (D.S.)
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China;
| | - Ambra Vestri
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (L.Z.); (A.V.); (V.M.); (M.R.); (D.S.)
| | - Valentina Marchesano
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (L.Z.); (A.V.); (V.M.); (M.R.); (D.S.)
| | - Massimo Rippa
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (L.Z.); (A.V.); (V.M.); (M.R.); (D.S.)
| | - Domenico Sagnelli
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (L.Z.); (A.V.); (V.M.); (M.R.); (D.S.)
| | - Gerardo Picazio
- Istituto Zooprofilattico Sperimentale del Mezzogiorno, 80055 Portici, Italy; (G.P.); (G.F.)
| | - Giovanna Fusco
- Istituto Zooprofilattico Sperimentale del Mezzogiorno, 80055 Portici, Italy; (G.P.); (G.F.)
| | - Jiaguang Han
- Center for Terahertz Waves and College of Precision Instrument and Optoelectronics Engineering, Tianjin University, Tianjin 300072, China;
| | - Jun Zhou
- Department of Microelectronic Science and Engineering, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
| | - Lucia Petti
- Institute of Applied Sciences and Intelligent Systems of CNR, 80072 Pozzuoli, Italy; (L.Z.); (A.V.); (V.M.); (M.R.); (D.S.)
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Anderson-Coughlin BL, Vanore A, Shearer AEH, Gartley S, Joerger RD, Sharma M, Kniel KE. Human Norovirus Surrogates Persist in Nontraditional Sources of Irrigation Water in Excess of 100 Days. J Food Prot 2023; 86:100024. [PMID: 36916591 DOI: 10.1016/j.jfp.2022.100024] [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: 05/25/2022] [Revised: 12/02/2022] [Accepted: 12/04/2022] [Indexed: 12/23/2022]
Abstract
Human norovirus (HuNoV) has been implicated as the leading cause of foodborne illness worldwide. The ability of HuNoV to persist in water can significantly impact food safety as agriculture and processing water could serve as vehicles of virus transmission. This study focused on the persistence and infectivity of the HuNoV surrogate viruses, murine norovirus (MNV), and Tulane virus (TV), after prolonged storage in diverse environmental water types currently used for agricultural irrigation. In this study, vegetable processing water (VW), brackish tidal surface water (SW), municipal reclaimed water (RW), and pond water (PW) were inoculated with each virus in a 1:10 v/v ratio containing virus at 3.5-4.5 logPFU/mL and stored at 16°C for 100 days. This time and temperature combination was chosen to mimic growing and harvest conditions in the mid-Atlantic area of the United States. Samples were then assayed for the presence of viral RNA using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) approximately weekly throughout the study. Persistence of MNV and TV was not significantly different (p > 0.05) from one another in any water sample (n = 7) or the control (HBSS). However, there was variability observed in viral persistence across water samples with significant differences observed between several water samples. The presence of intact viral capsids enclosing the genomes of MNV and TV were evaluated by an RNase assay coupled with RT-qPCR on specific timepoints and determined to be intact up to and at 100 days after inoculation. TV was also shown to remain infectious in a cell culture assay (TCID50) up to 100 days of incubation. These findings are significant in that the potential for not only detection of enteric viruses can occur long after a contamination event occurs but these viruses may also remain infectious.
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Affiliation(s)
| | - Adam Vanore
- Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716, USA
| | - Adrienne E H Shearer
- Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716, USA
| | - Samantha Gartley
- Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716, USA
| | - Rolf D Joerger
- Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716, USA
| | - Manan Sharma
- Environmental Microbial and Food Safety Laboratory, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705, USA
| | - Kalmia E Kniel
- Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716, USA.
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Tan MTH, Xue L, Wang D, Eshaghi Gorji M, Li Y, Gong Z, Li D. The globally re-emerging norovirus GII.2 manifests higher heat resistance than norovirus GII.4 and Tulane virus. J Appl Microbiol 2021; 132:2441-2449. [PMID: 34821445 DOI: 10.1111/jam.15379] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 11/18/2021] [Accepted: 11/20/2021] [Indexed: 12/11/2022]
Abstract
AIMS To compare the heat stability of two globally prevalent human norovirus (HuNoV) strains (GII.2[P16] and GII.4[P16]) and a commonly used HuNoV surrogate, Tulane virus (TV). METHODS AND RESULTS With the use of a newly developed zebrafish larvae platform, we measured the change of infectivity of HuNoV GII.2[P16] and GII.4[P16] toward mild heat treatment at 55°C for 5 min. TV was tested with the same experimental design. As a result, the virus infectivity measurement clearly indicated the higher heat resistance of HuNoV GII.2[P16] (no reduction) than GII.4[P16] (>0.8-log TCID50 ml-1 reduction) and TV (2.5-log TCID50 ml-1 reduction). Further exploration revealed higher virus structural stability of HuNoV GII.2 than GII.4 strains by the use of different clinical samples with different evaluation methods. CONCLUSION The inactivation data generated from the surrogate virus TV cannot be used directly to describe the inactivation of HuNoV. The phylogenetic classification of HuNoVs may correlate with the virus stability and/or circulation dynamics. SIGNIFICANCE AND IMPACT OF THE STUDY This study is expected to serve as an important reference when revisiting the numerous previous data evaluating HuNoV inactivation conditions in foods with the use of TV as the cultivable surrogate or with genuine HuNoV but using molecular methods. The higher resistance of NoV GII.2 strains than GII.4 strains toward inactivation treatment supplies a possible explanation for the global re-emerging of NoV GII.2 epidemic in recent years.
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Affiliation(s)
- Malcolm Turk Hsern Tan
- Department of Food Science & Technology, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Liang Xue
- Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, China
| | - Dapeng Wang
- Department of Food Science and Technology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Mohamad Eshaghi Gorji
- Department of Food Science & Technology, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Yan Li
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Zhiyuan Gong
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, Singapore
| | - Dan Li
- Department of Food Science & Technology, Faculty of Science, National University of Singapore, Singapore, Singapore
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Wang Q, Xie H, Zeng W, Wang L, Liu C, Wu J, Wang Y, Li Y, Bergmann SM. Development of indirect immunofluorescence assay for TCID 50 measurement of grass carp reovirus genotype II without cytopathic effect onto cells. Microb Pathog 2017; 114:68-74. [PMID: 29180293 DOI: 10.1016/j.micpath.2017.11.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Revised: 11/22/2017] [Accepted: 11/23/2017] [Indexed: 10/18/2022]
Abstract
Grass carp reovirus (GCRV) caused severe hemorrhagic disease with significant losses of fingerling and yearling grass carp, Cyenopharyngodon idellus, in southeast Asian. It was first isolated in 1983 in China, and clade analysis of the different GCRV isolates indicates there are at least three different genotypes I, II, and III. In recent years, GCRV genotype II has been determined as a dominant virus type which cause severe obvious clinical signs in fish but no cytopathic effect onto presently available cell culture. TCID50 is one of standard method to quantity infectious virus particles. In the present study, an indirect immunofluorescence assay (IFA) was developed using antibody against a protein encoded by segment 10 of GCRV genotype II. Moreover, the specific assay to differentitate GCRV of different genotypes and a sensitive assay for determination of GCRV genotype II were developed respectively. The results showed the IFA only can recognize genotype II virus at the lowest initial concentration of 550 genomic copies/ml. Furthermore, comparison of results obtained from qPCR and the TCID50 assay combined IFA was conducted. The results indicated that TCID50 of GCRV isolates JX0901 and HZ08 differs with 2 log steps reduction in the numbers of viruses compared with the number of genome copies detected by qPCR. The immunofluorescence assay developed is sensitive, specific, and the TCID50 combined with IFA will be a standardizable technique for the quantitation and detection of infectious GCRV in cell culture without cytolysis.
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Affiliation(s)
- Qing Wang
- Key Laboratory of Fishery Drug Development of Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology of Guangdong Province, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, Guangdong, PR China
| | - Hualiang Xie
- Key Laboratory of Fishery Drug Development of Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology of Guangdong Province, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, Guangdong, PR China; College of Veterinary, South China Agricultural Universtiy, Guangzhou, PR China
| | - Weiwei Zeng
- Key Laboratory of Fishery Drug Development of Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology of Guangdong Province, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, Guangdong, PR China.
| | - Linchuan Wang
- College of Veterinary, South China Agricultural Universtiy, Guangzhou, PR China
| | - Chun Liu
- Key Laboratory of Fishery Drug Development of Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology of Guangdong Province, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, Guangdong, PR China
| | - Jiexing Wu
- Key Laboratory of Fishery Drug Development of Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology of Guangdong Province, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, Guangdong, PR China
| | - Yingying Wang
- Key Laboratory of Fishery Drug Development of Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology of Guangdong Province, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, Guangdong, PR China
| | - Yingying Li
- Key Laboratory of Fishery Drug Development of Ministry of Agriculture, Key Laboratory of Aquatic Animal Immune Technology of Guangdong Province, Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Guangzhou, Guangdong, PR China
| | - Sven M Bergmann
- Institute of Infectology, Friedrich-Loffler-Institut (FLI), Federal Research Institute for Animal Health, Greifswald-Insel Riems, Germany.
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Li X, Huang R, Chen H. Evaluation of Assays to Quantify Infectious Human Norovirus for Heat and High-Pressure Inactivation Studies Using Tulane Virus. FOOD AND ENVIRONMENTAL VIROLOGY 2017; 9:314-325. [PMID: 28238030 DOI: 10.1007/s12560-017-9288-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 02/19/2017] [Indexed: 06/06/2023]
Abstract
We compared the heat and high hydrostatic pressure (HHP) inactivation results of Tulane virus (TV), a human norovirus (HuNoV) surrogate, obtained by plaque assay, direct quantitative reverse transcription PCR (RT-qPCR), porcine gastric mucin magnetic beads (PGM-MBs) binding assay followed by RT-qPCR (PGM/PCR), and propidium monoazide (PMA) assay followed by RT-qPCR (PMA/PCR). Heat and HHP inactivation of a HuNoV genotype I.1 (GI.1) strain and a genotype II.4 (GII.4) strain was also evaluated using those molecular assays. Viruses were heat treated at 50-90 °C for 2 min and HHP treated at 100-550 MPa at initial temperatures of 4 or 21 °C for 2 min. For heat treatment, the three molecular methods significantly underestimated the inactivation of TV. It could be logically concluded that the PGM/PCR assay was better than the PMA/PCR and direct RT-qPCR assays in estimating the inactivation of HuNoV GI.1. The three molecular methods were comparable in estimating the heat inactivation of GII.4. For HHP treatment, both PGM/PCR and PMA/PCR assays were able to estimate inactivation of TV at ≤~2-log reduction levels, but significantly underestimated its inactivation at >~2-log reduction levels. The direct RT-qPCR assay was the worst method for estimating HHP inactivation of TV. It could be logically concluded that the PGM/PCR and PMA/PCR assays were comparable in estimating the HHP inactivation of GI.1 and both were significantly better than the direct RT-qPCR assay. Among the three molecular methods, the PGM/PCR assay was the best in estimating the HHP inactivation of GII.4. These results demonstrated that the PGM/PCR assay was probably the method of choice in estimating the inactivation of HuNoV GI.1 and GII.4 for heat and HHP treatments, but this method would likely result in underestimation of HuNoV inactivation.
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Affiliation(s)
- Xinhui Li
- Department of Microbiology, University of Wisconsin-La Crosse, La Crosse, WI, 54601, USA
| | - Runze Huang
- Department of Animal & Food Sciences, University of Delaware, Newark, DE, 19716-2150, USA
| | - Haiqiang Chen
- Department of Animal & Food Sciences, University of Delaware, Newark, DE, 19716-2150, USA.
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Human Norovirus Aptamer Exhibits High Degree of Target Conformation-Dependent Binding Similar to That of Receptors and Discriminates Particle Functionality. mSphere 2016; 1:mSphere00298-16. [PMID: 27830193 PMCID: PMC5093151 DOI: 10.1128/msphere.00298-16] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 10/07/2016] [Indexed: 12/19/2022] Open
Abstract
Human noroviruses impose a considerable health burden globally. However, study of their inactivation is still challenging with currently reported cell culture models, as discrimination of infectious viral particles is still difficult. Traditionally, the ability of particles to bind putative carbohydrate receptors is conducted as a proxy for infectivity, but these receptors are inconsistent, expensive, and hard to purify/modify. We report a hitherto unexplored property of a different type of ligand, a nucleic acid aptamer, to mimic receptor binding behavior and assess capsid functionality for a selected strain of norovirus. These emerging ligands are cheaper, more stable, and easily synthesized/modified. The previously unutilized characteristic reported here demonstrates the fundamental potential of aptamers to serve as valuable, accessible tools for any microorganism that is difficult to cultivate/study. Therefore, this novel concept suggests a new use for aptamers that is of great value to the microbiological community—specifically that involving fastidious microbes. Although two in vitro cultivation methods have been reported, discrimination of infectious human norovirus particles for study of viral inactivation is still a challenge, as both rely on reverse transcriptase quantitative PCR. Histo-blood group antigen (HBGA) binding assays serve as a proxy for estimation of infectious particles; however, they are costly and difficult to purify/modify. Some evidence suggests that certain nucleic acid aptamers only bind intact target proteins, thus displaying a high degree of conformation-dependent binding. The objective of this proof-of-concept study was to characterize the degree of conformation-dependent binding a human norovirus aptamer, M6-2, displayed with the capsid of the norovirus GII.4 Sydney (SYV) strain as a model. SYV capsids were exposed to heat, and aptamer, receptor (HBGA), and antibody binding was assessed. M6-2 and the receptor displayed similarly little target sequence-dependent binding (2.0% ± 1.3% and 0.5% ± 1.2% signal, respectively) compared to that of NS14 (26.4% ± 3.9%). The decay rates calculated with M6-2 and the receptor were also not statistically significantly different (P > 0.05), and dynamic light scattering and electron microscopy confirmed these observations. Ligand docking simulations revealed multiple distinct contacts of M6-2 in the N-terminal P1 and P2 domains of the viral capsid, with some residues close to receptor binding residues. These data suggest that single-stranded DNA aptamers like M6-2 display a high degree of target conformation-dependent binding. It is the first time nucleic acid aptamers have had this characteristic utilized and investigated to discern the infectivity status of viral particles, and the data suggest that other aptamers may show promise as valuable ligands in the study of other fastidious microorganisms. IMPORTANCE Human noroviruses impose a considerable health burden globally. However, study of their inactivation is still challenging with currently reported cell culture models, as discrimination of infectious viral particles is still difficult. Traditionally, the ability of particles to bind putative carbohydrate receptors is conducted as a proxy for infectivity, but these receptors are inconsistent, expensive, and hard to purify/modify. We report a hitherto unexplored property of a different type of ligand, a nucleic acid aptamer, to mimic receptor binding behavior and assess capsid functionality for a selected strain of norovirus. These emerging ligands are cheaper, more stable, and easily synthesized/modified. The previously unutilized characteristic reported here demonstrates the fundamental potential of aptamers to serve as valuable, accessible tools for any microorganism that is difficult to cultivate/study. Therefore, this novel concept suggests a new use for aptamers that is of great value to the microbiological community—specifically that involving fastidious microbes.
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