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Atypical anti-glomerular basement membrane disease complicated by methicillin-susceptible Staphylococcus aureus infection-related rapidly progressive glomerulonephritis: a case report and literature review. CEN Case Rep 2021; 10:348-353. [PMID: 33460013 DOI: 10.1007/s13730-020-00564-9] [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: 08/21/2020] [Accepted: 12/04/2020] [Indexed: 10/22/2022] Open
Abstract
Atypical anti-glomerular basement membrane (GBM) disease, which is characterized by low levels of or negativity for anti-GBM antibodies in circulation but positivity in the kidney, has been recognized in this decade. However, a therapeutic strategy has not been established to date because its outcome is better than that of classic anti-GBM disease. This case report and literature review highlight atypical anti-GBM disease in infection-related rapidly progressive glomerulonephritis. A 72-year-old Japanese man diagnosed with methicillin-susceptible Staphylococcus aureus (MSSA)-induced vertebral osteomyelitis experienced for 2 months was referred to our hospital because of renal insufficiency. He developed rapidly progressive glomerulonephritis with a serum creatinine level of 6.8 mg/dL, C-reactive protein level of 9.7 mg/dL, urinary protein-to-creatinine ratio of 3.37 g/gCr, and gross hematuria. The serum anti-GBM antibody concentration was 3.5 U/mL, which was slightly above the normal range (< 3.0 U/mL). Conservative treatment, mainly with antibiotics, improved the symptoms and renal function. The serum anti-GBM antibody concentration peaked at 4.0 U/mL on day 7 and decreased to an undetectable range at the end of eight-week antibiotic therapy. This is the first case report describing the presentation and disappearance of serum anti-GBM antibody in a patient with MSSA infection. Conservative treatment may be effective for patients with atypical anti-GBM disease complicated by infectious diseases.
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2
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Development of homogeneous plasmonic potency assay using gold nanoparticle immunocomplexes. J Pharm Biomed Anal 2020; 181:113101. [PMID: 31982688 DOI: 10.1016/j.jpba.2020.113101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 01/06/2020] [Accepted: 01/06/2020] [Indexed: 11/23/2022]
Abstract
We evaluated the use of gold nanoparticles (AuNPs) platform in a homogenous assay for a potency measurement of a therapeutic monoclonal antibody (mAb). The recombinant human ligand protein to the therapeutic mAb was immobilized on AuNPs via functionalized self-assembled monolayers. Binding of the mAb to ligand lead to plasmonic signals that were detected faster in a homogeneous assay than the conventional enzyme-linked immunosorbent assay (ELISA). In this study, we demonstrated that the AuNP-based homogeneous plasmonic immunoassay (HPI) generated comparable potency values of a therapeutic mAb to a conventional binding ELISA in relatively shorter assay time and steps. Binding HPI can be potentially implemented as a potency assay for therapeutic mAbs in quality control laboratories.
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3
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Kim MS, Kim J. Multiplexed detection of pathogen-specific DNA using engineered zinc finger proteins without target amplification. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2016; 8:6696-6700. [PMID: 28127406 PMCID: PMC5258119 DOI: 10.1039/c6ay02102f] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Multiplexed detection of pathogen-specific DNA sequences in a simple and reliable way is in great demand for clinical and biomedical applications. However, there is still a lack of available DNA detection methods that are simple and pathogen-selective for point-of-care (POC) testing. Here, we report a novel zinc finger protein (ZFP)-based chemiluminescent method for direct detection of pathogenic double-stranded DNA (dsDNA) in a multiplexed platform. ZFPs are custom-designed to identify unique pathogenic DNA sequences. ZFP-based chemiluminescent detection of dsDNA provides sufficient sensitivity (≤50 fmol) and high specificity without target DNA amplification. Our study addresses the potential of developing a simple and selective pathogen detection method in a multiplexed fashion needed for POC application.
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Affiliation(s)
- Moon-Soo Kim
- Department of Chemistry, Western Kentucky University, Bowling Green, KY 42101 USA
| | - Juhwa Kim
- Department of Chemistry, Western Kentucky University, Bowling Green, KY 42101 USA
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4
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Gong B, Murray KD, Trimmer JS. Developing high-quality mouse monoclonal antibodies for neuroscience research - approaches, perspectives and opportunities. N Biotechnol 2016; 33:551-64. [PMID: 26644354 PMCID: PMC4884554 DOI: 10.1016/j.nbt.2015.11.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 11/11/2015] [Accepted: 11/23/2015] [Indexed: 10/22/2022]
Abstract
High-quality antibodies (Abs) are critical to neuroscience research, as they remain the primary affinity proteomics reagent used to label and capture endogenously expressed protein targets in the nervous system. As in other fields, neuroscientists are frequently confronted with inaccurate and irreproducible Ab-based results and/or reporting. The UC Davis/NIH NeuroMab Facility was created with the mission of addressing the unmet need for high-quality Abs in neuroscience research by applying a unique approach to generate and validate mouse monoclonal antibodies (mAbs) optimized for use against mammalian brain (i.e., NeuroMabs). Here we describe our methodology of multi-step mAb screening focused on identifying mAbs exhibiting efficacy and specificity in labeling mammalian brain samples. We provide examples from NeuroMab screens, and from the subsequent specialized validation of those selected as NeuroMabs. We highlight the particular challenges and considerations of determining specificity for brain immunolabeling. We also describe why our emphasis on extensive validation of large numbers of candidates by immunoblotting and immunohistochemistry against brain samples is essential for identifying those that exhibit efficacy and specificity in those applications to become NeuroMabs. We describe the special attention given to candidates with less common non-IgG1 IgG subclasses that can facilitate simultaneous multiplex labeling with subclass-specific secondary antibodies. We detail our recent use of recombinant cloning of NeuroMabs as a method to archive all NeuroMabs, to unambiguously define NeuroMabs at the DNA sequence level, and to re-engineer IgG1 NeuroMabs to less common IgG subclasses to facilitate their use in multiplex labeling. Finally, we provide suggestions to facilitate Ab development and use, as to design, execution and interpretation of Ab-based neuroscience experiments. Reproducibility in neuroscience research will improve with enhanced Ab validation, unambiguous identification of Abs used in published experiments, and end user proficiency in Ab-based assays.
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Affiliation(s)
- Belvin Gong
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA 95616, United States
| | - Karl D Murray
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA 95616, United States; Center for Neuroscience, University of California, Davis, Davis, CA 95616, United States
| | - James S Trimmer
- Department of Neurobiology, Physiology and Behavior, University of California, Davis, Davis, CA 95616, United States; Department of Physiology and Membrane Biology, University of California Davis School of Medicine, Davis, CA 95616, United States.
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5
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Moore MD, Escudero-Abarca BI, Suh SH, Jaykus LA. Generation and characterization of nucleic acid aptamers targeting the capsid P domain of a human norovirus GII.4 strain. J Biotechnol 2015; 209:41-9. [PMID: 26080079 DOI: 10.1016/j.jbiotec.2015.06.389] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 06/03/2015] [Accepted: 06/09/2015] [Indexed: 12/20/2022]
Abstract
Human noroviruses (NoV) are the leading cause of acute viral gastroenteritis worldwide. Significant antigenic diversity of NoV strains has limited the availability of broadly reactive ligands for design of detection assays. The purpose of this work was to produce and characterize single stranded (ss)DNA aptamers with binding specificity to human NoV using an easily produced NoV target-the P domain protein. Aptamer selection was done using SELEX (Systematic Evolution of Ligands by EXponential enrichment) directed against an Escherichia coli-expressed and purified epidemic NoV GII.4 strain P domain. Two of six unique aptamers (designated M1 and M6-2) were chosen for characterization. Inclusivity testing using an enzyme-linked aptamer sorbent assay (ELASA) against a panel of 14 virus-like particles (VLPs) showed these aptamers had broad reactivity and exhibited strong binding to GI.7, GII.2, two GII.4 strains, and GII.7 VLPs. Aptamer M6-2 exhibited at least low to moderate binding to all VLPs tested. Aptamers significantly (p<0.05) bound virus in partially purified GII.4 New Orleans outbreak stool specimens as demonstrated by ELASA and aptamer magnetic capture (AMC) followed by RT-qPCR. This is the first demonstration of human NoV P domain protein as a functional target for the selection of nucleic acid aptamers that specifically bind and broadly recognize diverse human NoV strains.
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Affiliation(s)
- Matthew D Moore
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, 315 Schaub Hall, 400 Dan Allen Drive, Raleigh, NC 27695, USA.
| | - Blanca I Escudero-Abarca
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, 315 Schaub Hall, 400 Dan Allen Drive, Raleigh, NC 27695, USA
| | - Soo Hwan Suh
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, 315 Schaub Hall, 400 Dan Allen Drive, Raleigh, NC 27695, USA
| | - Lee-Ann Jaykus
- Department of Food, Bioprocessing and Nutrition Sciences, North Carolina State University, 315 Schaub Hall, 400 Dan Allen Drive, Raleigh, NC 27695, USA
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6
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Tsaloglou MN, Jacobs A, Morgan H. A fluorogenic heterogeneous immunoassay for cardiac muscle troponin cTnI on a digital microfluidic device. Anal Bioanal Chem 2014; 406:5967-76. [PMID: 25074544 DOI: 10.1007/s00216-014-7997-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2014] [Revised: 06/18/2014] [Accepted: 06/24/2014] [Indexed: 11/24/2022]
Abstract
We describe a fluorogenic two-site noncompetitive heterogeneous immunoassay with magnetic beads on a low-voltage digital microfluidic platform using closed electrowetting-on-dielectric (EWOD). All the steps of an enzyme-linked immunosorbent assay (ELISA) were performed on the device using 9H-(1, 3-dichloro-9, 9-dimethylacridin-2-one-7-yl) phosphate as the fluorogenic substrate for the enzyme alkaline phosphatase. The performance of the system was demonstrated with cardiac marker Troponin I (cTnI) as a model analyte in phosphate-buffered saline samples. cTnI was detected within the diagnostically relevant range with a limit of detection of 2.0 ng/mL (CV = 6.47 %). Washing of magnetic beads was achieved by movement through a narrow region of buffer bridging one drop to another with minimal fluid transfer. More than 90 % of the unbound reagents were removed after five washes. Further experiments testing human blood serum on the same platform demonstrated a sample-to-answer time at ∼18.5 min detecting 6.79 ng/mL cTnI.
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Affiliation(s)
- Maria-Nefeli Tsaloglou
- Electronics and Computer Science and Institute for Life Sciences, University of Southampton, Southampton, SO17 1BJ, UK,
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Dudal S, Baltrukonis D, Crisino R, Goyal MJ, Joyce A, Osterlund K, Smeraglia J, Taniguchi Y, Yang J. Assay formats: Recommendation for best practices and harmonization from the global bioanalysis consortium harmonization team. AAPS J 2014; 16:194-205. [PMID: 24343771 PMCID: PMC3933581 DOI: 10.1208/s12248-013-9552-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Accepted: 11/21/2013] [Indexed: 11/30/2022] Open
Abstract
As part of the GBC (Global Bioanalysis Consortium), the L3 assay format team has focused on reviewing common platforms used to support ligand binding assays in the detection of biotherapeutics. The following review is an overview of discussions and presentations from around the globe with a group of experts from different companies to allow an international harmonization of common practices and suggestions for different platforms. Some of the major platforms include Gyrolab, Erenna, RIA, AlphaLISA, Delfia, Immuno-PCR, Luminex, BIAcore, and ELISAs. The review is meant to support bioanalysts in taking decisions between different platforms depending on the needs of the analyte with a number of recommendations to help integration of platforms into a GLP environment.
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Affiliation(s)
- Sherri Dudal
- Novartis Pharma AG, Novartis Institute for Biomedical Research, 144 Klybeckstrasse, 4052, Basel, Switzerland,
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Zhang S, Garcia-D'Angeli A, Brennan JP, Huo Q. Predicting detection limits of enzyme-linked immunosorbent assay (ELISA) and bioanalytical techniques in general. Analyst 2014; 139:439-45. [DOI: 10.1039/c3an01835k] [Citation(s) in RCA: 137] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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9
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Simkins SG, Knapp SL, Brough GH, Lenz KL, Barley-Maloney L, Baker JP, Dekking L, Wai H, Dixon EP. Generation of monoclonal antibodies to the AML1-ETO fusion protein: strategies for overcoming high homology. Hybridoma (Larchmt) 2011; 30:433-43. [PMID: 22008070 DOI: 10.1089/hyb.2011.0037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The chromosomal translocation t(8;21) often found in acute myeloid leukemia generates an oncogenic fusion protein AML1-ETO. This chimeric oncoprotein disrupts wild-type AML1 function and dysregulates genes important for normal myelopoiesis. Monoclonal antibodies that can capture and detect the AML1-ETO fusion protein would help with early diagnosis and treatment prognosis of acute myeloid leukemia. We report the development of murine monoclonal antibodies (MAbs) that specifically bind epitopes encoded by either AML1 or ETO. Since alignment to the human ETO protein indicated almost 100% homology to the mouse ortholog, a strategy was needed to instruct humoral immunity in mice to focus and respond to self-epitopes. Our strategy to develop capture/detector reagents involved producing MAbs that would bind to epitopes within the non-fused myelopic protein (i.e., either AML1 or ETO). This included a process to select antibodies for their ability to also recognize the translocated chromosomal AML1-ETO fusion protein and to identify complementary capture/detector antibody pairs. Construction of a peptide hapten-carrier complex and use of a rapid immunization protocol resulted in IgM-IgG ETO specific MAbs. These MAbs bound specifically to a recombinant form of AML1-ETO fusion protein expressed in HEK and to an endogenous AML1-ETO form of the fusion protein expressed in Kasumi-1. We report the development of murine hybridoma MAbs derived from immunizations with a peptide "self-epitope." Our findings provide a potential strategy to instruct humoral immunity in mice to focus and respond to self-epitopes. This strategy has been validated with the oncogenic fusion protein AML1-ETO involved in acute myeloid leukemia.
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Affiliation(s)
- Stephen G Simkins
- BD Diagnostics, Women's Health and Cancer, Durham, North Carolina, USA
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10
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Liao K, Sikkema D, Wang C, Chen K, DeWall S, Lee TN. Development and validation of a cell-based SEAP reporter assay for the detection of neutralizing antibodies against an anti-IL-13 therapeutic antibody. J Immunol Methods 2011; 375:258-63. [PMID: 22001556 DOI: 10.1016/j.jim.2011.09.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 09/14/2011] [Accepted: 09/30/2011] [Indexed: 11/17/2022]
Abstract
A cell-based bioassay capable of detecting neutralizing antibodies (NAb) specific to a therapeutic anti-IL-13 monoclonal antibody was developed, validated and used to analyze normal human and asthma serum samples. At the time of this study, a neutralizing assay was unavailable for anti-IL-13 antibody therapeutics with sufficient rigor for validation. Thus, we describe here a method and considerations for validation. The assay used IL-13 responsive HEK293 cells transfected with a secreted embryonic alkaline phosphatase (SEAP) reporter gene. Cells were plated at 5.4×10(4) per assay well due to 90% confluence on the subsequent day. Optimal IL-13 and anti-IL-13 concentrations were determined to be 600 pg/mL and 900 ng/mL respectively. We demonstrated the assay's cut point, sensitivity, specificity/cross reactivity, selectivity/matrix interference, and precision. Also, we demonstrated how the drug inhibitory concentration (IC(50), IC(75), and IC(90)) can affect sensitivity and dynamic range/assay window. We characterized the differences in assay response between serum samples of normal population and asthma population. Asthma samples demonstrated an elevated OD ratio in average compared to normal samples. Thus, separate cut points were needed and calculated to be 1.78 and 2.43 for normal and asthma serum, respectively. The assay sensitivity was 670 ng/mL with the positive control (affinity purified rabbit anti-drug polyclonal antibodies). Potential false positives resulting from endogenous serum cytokines including IL-13, IL-4, and Interferon alpha (INF-α) were evaluated and the results indicated that the interfering concentrations for these cytokines are much higher than the respective physiological concentrations. Based on these data, the risk of false positive by endogenous cytokines was considered to be low. In addition, irrelevant anti-drug positive control antibodies were evaluated for assay specificity and did not demonstrate neutralizing capability. Further, no matrix interference in the intended patient population was found when using a final assay serum concentration of 16.7%. The validated assay had acceptable intra- and inter- assay precision in that all %CVs were ≤25%. Overall, this assay successfully proceeded through validation and was used to determine NAb responses within serum samples.
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Affiliation(s)
- Karen Liao
- Clinical Immunology, GlaxoSmithKline, King Of Prussia, PA 19406, United States
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11
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Samineni S, Parvataneni S, Kelly C, Gangur V, Karmaus W, Brooks K. Optimization, Comparison, and Application of Colorimetric vs. Chemiluminescence Based Indirect Sandwich ELISA for Measurement of Human IL‐23. J Immunoassay Immunochem 2006; 27:183-93. [PMID: 16711255 DOI: 10.1080/15321810600573051] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Currently, there is neither a published ELISA method nor it is clear whether chemiluminescence substrates would provide better sensitivity vs. colorimetric substrates for measuring human IL-23-a recently described Type-1 immunity associated cytokine. Initially, we optimized a colorimetric ELISA using p-nitro-phenyl phosphate substrate. Subsequently, we compared it with chemiluminescence substrates that provided approximately 5-fold enhanced sensitivity (mean sensitivity; 26.3 pg/mL vs. colorimetric assay, 131 pg/mL; p < 0.01). Both methods were reliable, with <10% inter- and intra-assay variations. We then found that the chemiluminescence method was useful in situations where human IL-23 was not readily measurable by a colorimetric method.
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Affiliation(s)
- Sridhar Samineni
- Food Allergy & Immunology Laboratory, Department of Food Science & Human Nutrition, Nutritional Immunology Program, Michigan State University, East Lansing, Michigan 48824, USA
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12
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Che XY, Di B, Zhao GP, Wang YD, Qiu LW, Hao W, Wang M, Qin PZ, Liu YF, Chan KH, Cheng VCC, Yuen KY. A patient with asymptomatic severe acute respiratory syndrome (SARS) and antigenemia from the 2003-2004 community outbreak of SARS in Guangzhou, China. Clin Infect Dis 2006; 43:e1-5. [PMID: 16758408 PMCID: PMC7108013 DOI: 10.1086/504943] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Accepted: 03/18/2006] [Indexed: 01/08/2023] Open
Abstract
An asymptomatic case of severe acute respiratory syndrome (SARS) occurred early in 2004, during a community outbreak of SARS in Guangzhou, China. This was the first time that a case of asymptomatic SARS was noted in an individual with antigenemia and seroconversion. The asymptomatic case patient and the second index case patient with SARS in the 2003-2004 outbreak both worked in the same restaurant, where they served palm civets, which were found to carry SARS-associated coronaviruses. Epidemiological information and laboratory findings suggested that the findings for the patient with asymptomatic infection, together with the findings from previously reported serological analyses of handlers of wild animals and the 4 index case patients from the 2004 community outbreak, reflected a likely intermediate phase of animal-to-human transmission of infection, rather than a case of human-to-human transmission. This intermediate phase may be a critical stage for virus evolution and disease prevention.
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Affiliation(s)
- Xiao-yan Che
- Center of Laboratory, Zhujiang Hospital, Southern Medical University, Guangzhou
- Reprints or correspondence: Dr. Xiao-yan Che, Center of Laboratory, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, People's Republic of China ()
| | - Biao Di
- Center for Disease Control and Prevention of Guangzhou, Guangzhou
| | - Guo-ping Zhao
- Laboratory of Disease and Health Genomics, Chinese National Human Genome Center at Shanghai, Shanghai
- Dr. Guo-ping Zhao, Laboratory of Disease and Health Genomics, Chinese National Human Genome Center at Shanghai, Shanghai 201203, People's Republic of China ()
| | - Ya-di Wang
- Center of Laboratory, Zhujiang Hospital, Southern Medical University, Guangzhou
| | - Li-wen Qiu
- Center of Laboratory, Zhujiang Hospital, Southern Medical University, Guangzhou
| | - Wei Hao
- Center of Laboratory, Zhujiang Hospital, Southern Medical University, Guangzhou
| | - Ming Wang
- Center for Disease Control and Prevention of Guangzhou, Guangzhou
| | - Peng-zhe Qin
- Center for Disease Control and Prevention of Guangzhou, Guangzhou
| | - Yu-fei Liu
- Center for Disease Control and Prevention of Guangzhou, Guangzhou
| | - Kwok-hong Chan
- Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
| | - Vincent C. C. Cheng
- Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
| | - Kwok-yung Yuen
- Department of Microbiology, The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China
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Khaw BA, Rammohan R, Abu-Taha A. Bispecific Enzyme-Linked Signal-Enhanced Immunoassay with Subattomole Sensitivity. Assay Drug Dev Technol 2005; 3:319-27. [PMID: 15971993 DOI: 10.1089/adt.2005.3.319] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A bispecific enzyme-linked signal-enhanced immunoassay (BiELSIA) was developed with markedly increased sensitivity. Antimyosin, the detection antibody, was linked to the signal probespecific antibody. Probes consisted of diethylenetriamine pentaacetic acids attached to polylysine modified with up to seven or eight horseradish peroxidase (HRP) units. Each bispecific antibody bound two polymer probes, providing twice the signal. Using BiELSIA in a competitive inhibition immunoassay format with an average of 1.5, 3, 4.5, 6, and 7.5 HRP units per polymer-probe, the sensitivity of standard enzyme-linked immunosorbent assay (10(13) mole) was increased to 10(15), 10(18), 10(19), 10(20), and 10(-21) mol (< or = 1,000 molecules), respectively. BiELSIA detected cardiac myosin heavy chain fragments in sera of patients obtained at the time of emergency department admission for acute myocardial infarction, but not in normal sera. This technology should be applicable for detection of cancer, human immunodeficiency virus, prion, and other antigens that are present in concentrations too low for detection by current immunoassays.
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Affiliation(s)
- Ban-An Khaw
- The Center for Cardiovascular Targeting, Bouve College of Health Sciences, School of Pharmacy, Northeastern University, Boston, MA 02115, USA.
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Siddiqui J, Remick DG. Improved sensitivity of colorimetric compared to chemiluminescence ELISAs for cytokine assays. J Immunoassay Immunochem 2004; 24:273-83. [PMID: 12953972 DOI: 10.1081/ias-120022937] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Cytokines are often measured using ELISAs and chemiluminescence (CMIL) is reported to exhibit increased sensitivity compared to colorimetric (COL) assays. CMIL also has a wider dynamic detection range. We sought to directly compare ELISAs for measuring human TNF and IL-8 using CMIL or COL. CMIL substrates with glow fluorescence were obtained from 4 different commercial sources while the COL substrate was TMB. ELISAs for TNF and IL-8 were run under identical conditions and the standard curve extended from 0.5 to 4000 pg/ML. The COL substrate demonstrated a sigmoid shaped curve when plotted on a log-linear scale while the CMIL continued to increase up to the highest concentration. Both substrates were modeled most accurately by a 4 parameter equation with R values > 0.99. The standard curves for both the IL-8 and TNF demonstrated a lower limit of detection (LLD) for the COL comparable to the CMIL detection system. To precisely define the LLD quadruplicate blanks were run and the mean plus 4 standard deviations were used. By these criteria, the COL assay routinely had a LLD of < 1.5 pg/ML which was better than any of the CMIL substrates. Our data demonstrate the COL assays have the same or better sensitivity than CMIL and are significantly less expensive.
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Affiliation(s)
- Javed Siddiqui
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0602, USA
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