WorldWideScience

Sample records for accurate antibody assays

  1. Immunometric Antibody Sandwich Enzyme-Linked Immunosorbent Assay.

    Science.gov (United States)

    Kohl, Thomas O; Ascoli, Carl A

    2017-06-01

    The antibody sandwich enzyme-linked immunosorbent assay (ELISA) is the most commonly used assay for rapid and accurate detection of antigens. It displays greater sensitivity compared with the indirect ELISA and can be used to determine absolute antigen concentrations in unknown samples provided purified antigen standards are available, although it requires the use of two different antibodies. Briefly, wells are coated with antigen-specific capture antibody then incubated with samples containing unknown antigen. Washing removes unbound antigen and exogenous sample protein before incubation with a second antigen-specific detection antibody, washing, and reincubation with a reporter-labeled tertiary antibody. After tertiary antibody is washed off, substrate is added and hydrolysis is measured spectrophotometrically. The signal intensity is directly proportional to the concentration of the antigen in the test sample. © 2017 Cold Spring Harbor Laboratory Press.

  2. Standardization of anti-DNA antibody assays.

    Science.gov (United States)

    Pisetsky, David S

    2013-07-01

    Antibodies to DNA (anti-DNA) are the serological hallmark of systemic lupus erythematosus and represent important biomarkers for clinical and research purposes. These antibodies are part of a family of antibodies to nucleosomes and bind to conserved sites widely present on DNA. While the value of anti-DNA as a biomarker is well established, the assay for these antibodies has involved a variety of DNA sources and systems to detect DNA-anti-DNA interactions. The influence of these variations on antibody detection has complicated assay standardization. As an antigen, DNA has unique features since it is a highly charged polymer that has structural heterogeneity. This heterogeneity can affect antigenicity which can vary on the basis of DNA origin, size, conformation and mobility. In addition, as a polymer, DNA can promote patterns of antibody binding based on monogamous or bivalent interaction which require an extended polynucleotide structure. Understanding the nature of DNA as an antigen can facilitate interpretation of serological tests and underpin efforts at better standardization.

  3. Production and assay of forskolin antibodies

    Energy Technology Data Exchange (ETDEWEB)

    Ho, L.T.; Ho, R.J.

    1986-05-01

    Forskolin (Fo), a cardiovascular active diterpene of plant origin, has been widely used as a research tool in regulation of the catalytic activity of adenylate cyclase (AC). A linear relationship of Fo binding to plasma membrane with activation of AC has been reported. The present abstract describes the production and assay of Fo antibodies (AB). 7-0-Hemisuccinyl-7-deacetyl Fo, coupled to either human serum albumin or goat IgG, was injected into goats to elicit AB to Fo haptan. AB to Fo in antiserum or an isolated IgG fraction was tested by two assay methods, a radioimmunoassay using /sup 3/H-Fo as a tracer and a colorimetric enzyme-linked immunosorbent assay (ELISA) using horse radish peroxidase-rabbit anti goat IgG as indicator. The titers for Fo antiserum were 4000-10,000. In the defined assay condition, approximately 20-25% of the added /sup 3/H-Fo was found to bind to AB. The bound radioactivity was displaced by Fo-HSA or Fo-goat IgG or free unlabelled Fo ranging from 0.5-50 pmol/tube, or 5-500 nM. The IC/sub 50/ was approximately 8-10 pmol/tube or 80-100 nM. The binding of HRP-rabbit anti goat IgG in the ELISA was inhibited by proper Fo conjugate. The development of methods for production and assay for Fo AB may be useful in the study of mechanism of activation of AC by Fo and Fo-like compound.

  4. Immunometric Double-Antibody Sandwich Enzyme-Linked Immunosorbent Assay.

    Science.gov (United States)

    Kohl, Thomas O; Ascoli, Carl A

    2017-06-01

    The double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) is preferentially used to determine the concentration of unknown antibody in a sample. Pure antigen is not required in this assay; however, the use of a reporter-labeled detection antibody is essential. The double-antibody sandwich ELISA is suitable for epitope mapping of different monoclonal antibodies that have been generated against a single antigen. First, plates are coated with a capture antibody specific for immunoglobulins generated by immunization of a host species. Next, the test antibody solution (e.g., serum) is incubated with the capture antibody to facilitate binding. The plates are washed to remove unbound antibody, and then antigen is added. The plates are washed again followed by the addition of an antigen-specific reporter-labeled antibody. Following incubation, unbound reporter antibody is washed off, and reporter-specific substrate is added. Reporter-mediated substrate hydrolysis is visualized and measured. The signal is proportional to the number of test antibodies present in the serum. © 2017 Cold Spring Harbor Laboratory Press.

  5. A novel assay for monitoring internalization of nanocarrier coupled antibodies

    Directory of Open Access Journals (Sweden)

    Pickering Edward M

    2006-10-01

    Full Text Available Abstract Background Discovery of tumor-selective antibodies or antibody fragments is a promising approach for delivering therapeutic agents to antigen over-expressing cancers. Therefore it is important to develop methods for the identification of target- and function specific antibodies for effective drug delivery. Here we describe a highly selective and sensitive method for characterizing the internalizing potential of multivalently displayed antibodies or ligands conjugated to liposomes into tumor cells. The assay requires minute amounts of histidine-tagged ligand and relies on the non-covalent coupling of these antibodies to fluorescent liposomes containing a metal ion-chelating lipid. Following incubation of cells with antibody-conjugated liposomes, surface bound liposomes are gently removed and the remaining internalized liposomes are quantitated based on fluorescence in a high throughput manner. We have termed this methodology "Chelated Ligand Internalization Assay", or CLIA. Results The specificity of the assay was demonstrated with different antibodies to the ErbB-2 and EGF receptors. Antibody-uptake correlated with receptor expression levels in tumor cell lines with a range of receptor expression. Furthermore, Ni-NTA liposomes containing doxorubicin were used to screen for the ability of antibodies to confer target-specific cytotoxicity. Using an anti-ErbB2 single chain Fv (scFv (F5 antibody, cytotoxicity could be conferred to ErbB2-overexpressing cells; however, a poly(ethylene glycol-linked lipid (DSPE-PEG-NTA-Ni was necessary to allow for efficient loading of the drug and to reduce nonspecific drug leakage during the course of the assay. Conclusion The CLIA method we describe here represents a rapid, sensitive and robust assay for the identification and characterization of tumor-specific antibodies capable of high drug-delivery efficiency when conjugated to liposomal nanocarriers.

  6. Monoclonal antibody technologies and rapid detection assays

    Science.gov (United States)

    Novel methodologies and screening strategies will be outlined on the use of hybridoma technology for the selection of antigen specific monoclonal antibodies. The development of immunoassays used for diagnostic detection of prions and bacterial toxins will be discussed and examples provided demonstr...

  7. A platelet monoclonal antibody inhibition assay for detection of glycoprotein IIb/IIIa-related platelet alloantibodies.

    Science.gov (United States)

    Reiner, A P; Teramura, G; Nelson, K A; Slichter, S J

    1995-08-18

    Post-transfusion purpura (PTP) and neonatal alloimmune thrombocytopenia (NAT) result from formation of alloantibodies to platelet membrane glycoprotein-associated antigens. The detection and identification of platelet-specific alloantibodies in patient sera is often complicated by the presence of co-existing HLA antibodies and/or more than one platelet specificity in the same serum. We describe a solid phase assay that specifically detects antibodies to platelet membrane associated alloantigens by measuring the ability of patient antisera to inhibit the binding of glycoprotein GPIIb or GPIIIa monoclonal antibodies to intact platelets. When tested in the GPIIIa assay against a panel of random platelet donors, the reactivities of two known PLAI antisera that also contained different HLA antibodies were highly correlated (r = 0.99) and allowed PLA phenotyping of the population. A standard direct binding platelet ELISA, on the other hand, was unable to accurately PLA phenotype the same population. The reactivities of two known Baka antisera (one containing additional anti-PLA2 and the other anti-Brb specificities) were highly correlated (r = 0.95) in the GPIIb assay, and Bak phenotype determination was similarly accomplished for a random platelet panel. Furthermore, a comparison of platelet phenotype results (using the monoclonal inhibition assay) and genotype results (using DNA analysis) for the PLA and Bak systems showed a concordance of 98% for 146 alleles tested. In conclusion, the platelet monoclonal antibody inhibition assay: (1) allows determination of platelet-specific alloantibodies in the presence of contaminating HLA antibodies and/or in sera containing multiple platelet alloantibodies; (2) allows accurate platelet phenotyping for the GPIIIa-associated PLA and GPIIb-associated Bak antigen systems; and (3) may be applicable to the detection of other known or even novel platelet glycoprotein-associated antigens.

  8. A Rapid Zika Diagnostic Assay to Measure Neutralizing Antibodies in Patients

    Directory of Open Access Journals (Sweden)

    Chao Shan

    2017-03-01

    Full Text Available The potential association of microcephaly and other congenital abnormalities with Zika virus (ZIKV infection during pregnancy underlines the critical need for a rapid and accurate diagnosis. Due to the short duration of ZIKV viremia in infected patients, a serologic assay that detects antibody responses to viral infection plays an essential role in diagnosing patient specimens. The current serologic diagnosis of ZIKV infection relies heavily on the labor-intensive Plaque Reduction Neutralization Test (PRNT that requires more than one-week turnaround time and represents a major bottleneck for patient diagnosis. To overcome this limitation, we have developed a high-throughput assay for ZIKV and dengue virus (DENV diagnosis that can attain the “gold standard” of the current PRNT assay. The new assay is homogeneous and utilizes luciferase viruses to quantify the neutralizing antibody titers in a 96-well format. Using 91 human specimens, we showed that the reporter diagnostic assay has a higher dynamic range and maintains the relative specificity of the traditional PRNT assay. Besides the improvement of assay throughput, the reporter virus technology has also shortened the turnaround time to less than two days. Collectively, our results suggest that, along with the viral RT-PCR assay, the reporter virus-based serologic assay could be potentially used as the first-line test for clinical diagnosis of ZIKV infection as well as for vaccine clinical trials.

  9. Antibodies to poliovirus detected by immunoradiometric assay with a monoclonal antibody

    Energy Technology Data Exchange (ETDEWEB)

    Spitz, M.; Fossati, C.A.; Schild, G.C.; Spitz, L.; Brasher, M. (National Inst. for Biological Standards and Control, London (UK))

    1982-10-01

    An immunoradiometric assay (IRMA) for the assay of antibodies to poliovirus antigens is described. Dilutions of the test sera or whole (finger prick) blood samples were incubated with the poliovirus antigen bound to a solid phase and the specific antibody was detected by the addition of a mouse anti-human IgG monoclonal antibody (McAb), which was itself revealed by iodinated sheep IgG antimouse F(ab). The authors have shown that this technique is suitable for the estimation of IgG anti-poliovirus antibodies induced in children following polio vaccine. The present study shows that SPRIA provides a simple and inexpensive method for serological studies with poliovirus particularly for use in large-scale surveys.

  10. A Neutralizing Antibody Assay Based on a Reporter of Antibody-Dependent Cell-Mediated Cytotoxicity.

    Science.gov (United States)

    Wu, Yuling; Li, Jia J; Kim, Hyun Jun; Liu, Xu; Liu, Weiyi; Akhgar, Ahmad; Bowen, Michael A; Spitz, Susan; Jiang, Xu-Rong; Roskos, Lorin K; White, Wendy I

    2015-11-01

    Benralizumab is a humanized anti-IL5 receptor α (IL5Rα) monoclonal antibody (mAb) with enhanced (afucosylation) antibody-dependent cell-mediated cytotoxicity (ADCC) function. An ADCC reporter cell-based neutralizing antibody (NAb) assay was developed and characterized to detect NAb against benralizumab in human serum to support the clinical development of benralizumab. The optimal ratio of target cells to effector cells was 3:1. Neither parental benralizumab (fucosylated) nor benralizumab Fab resulted in ADCC activity, confirming the requirement for ADCC activity in the NAb assay. The serum tolerance of the cells was determined to be 2.5%. The cut point derived from normal and asthma serum samples was comparable. The effective range of benralizumab was determined, and 35 ng/mL [80% maximal effective concentration (EC80)] was chosen as the standard concentration to run in the assessment of NAb. An affinity purified goat anti-benralizumab polyclonal idiotype antibody preparation was shown to have NAb since it inhibited ADCC activity in a dose-dependent fashion. The low endogenous concentrations of IL5 and soluble IL5 receptor (sIL5R) did not demonstrate to interfere with the assay. The estimated assay sensitivities at the cut point were 1.02 and 1.10 μg/mL as determined by the surrogate neutralizing goat polyclonal and mouse monoclonal anti-drug antibody (ADA) controls, respectively. The assay can detect NAb (at 2.5 μg/mL) in the presence of 0.78 μg/mL benralizumab. The assay was not susceptible to non-specific matrix effects. This study provides an approach and feasibility of developing an ADCC cell-based NAb assay to support biopharmaceuticals with an ADCC function.

  11. Identification of anti-HPA-1a allo-antibodies using IgG platelet antibody detection and crossmatch system assay with Galileo Echo.

    Science.gov (United States)

    Di Cristofaro, Julie; Frassati, Coralie; Montagnie, Rolande; Basire, Agnes; Merieux, Yves; Picard, Christophe

    2015-01-01

    Fetal/neonatal allo-immune thrombocytopenia is the most frequent and the most dangerous clinical condition involving anti-human platelet antigens (HPA)-1a allo-antibodies. Anti-HPA-1a allo-immunization requires rapid and accurate diagnosis to determine appropriate treatment. The Capture-P Ready-Screen assay (C-PRS) is a new qualitative immunoassay to detect IgG anti-human leukocyte antigen (HLA) and anti-HPA allo-antibodies. The aim of this study is to assess the identification of anti-HPA-1a allo-antibodies using the C-PRS assay, associated with HLA class I stripping reagents, on the automated benchtop analyzer Galileo Echo. Forty-nine sera were analyzed: without anti-HLA class I or anti-HPA allo-antibodies, with anti-HLA class I allo-antibodies, with anti-HPA-1a allo-antibodies, among which with anti-HLA class I allo-antibodies. None of the samples without allo-antibodies were reactive. Only anti-HLA antibodies, detected by cytotoxicity-dependent complement and not by Luminex, remained positive before and after stripping reagents. Of the 13 samples, anti-HPA-1a allo-antibodies that were correctly identified before and after incubation with HLA assassin reagent were 70% and 85%, respectively. Anti-glycoprotein auto-antibodies and anti-HLA allo-antibodies do not interfere with the detection of anti-HPA-1a antibodies. This preliminary study indicates that further improvement of the test will be helpful in developing a clinically useful assay in the future.

  12. Accurate non-invasive image-based cytotoxicity assays for cultured cells

    Directory of Open Access Journals (Sweden)

    Brouwer Jaap

    2010-06-01

    Full Text Available Abstract Background The CloneSelect™ Imager system is an image-based visualisation system for cell growth assessment. Traditionally cell proliferation is measured with the colorimetric MTT assay. Results Here we show that both the CloneSelect Imager and the MTT approach result in comparable EC50 values when assaying the cytotoxicity of cisplatin and oxaliplatin on various cell lines. However, the image-based technique was found non-invasive, considerably quicker and more accurate than the MTT assay. Conclusions This new image-based technique has the potential to replace the cumbersome MTT assay when fast, unbiased and high-throughput cytotoxicity assays are requested.

  13. Measuring immunoglobulin g antibodies to tetanus toxin, diphtheria toxin, and pertussis toxin with single-antigen enzyme-linked immunosorbent assays and a bead-based multiplex assay.

    Science.gov (United States)

    Reder, Sabine; Riffelmann, Marion; Becker, Christian; Wirsing von König, Carl Heinz

    2008-05-01

    Bead-based assay systems offer the possibility of measuring several specific antibodies in one sample simultaneously. This study evaluated a vaccine panel of a multianalyte system that measures antibodies to tetanus toxin, diphtheria toxin, and pertussis toxin (PT) from Bordetella pertussis. The antibody concentrations of human immunoglobulin G (IgG) to PT, tetanus toxin, and diphtheria toxin were measured in 123 serum pairs (total of 246 sera) from a vaccine study. The multianalyte bead assay was compared to a standardized in-house IgG- anti-PT enzyme-linked immunosorbent assay (ELISA) of the German reference laboratory for bordetellae, as well as to various commercially available ELISAs for anti-PT IgG, anti-tetanus IgG, and anti-diphtheria IgG. The results of the multiplex assay regarding the antibodies against diphtheria toxin compared favorably with a regression coefficient of 0.938 for values obtained with an ELISA from the same manufacturer used as a reference. Similarly, antibodies to tetanus toxin showed a correlation of 0.910 between the reference ELISA and the multianalyte assay. A correlation coefficient of 0.905 was found when an "in-house" IgG anti-PT and the multiplex assay were compared. Compared to single ELISA systems from two other manufacturers, the multiplex assay performed similarly well or better. The multianalyte assay system was a robust system with fast and accurate results, analyzing three parameters simultaneously in one sample. The system was well suited to quantitatively determine relevant vaccine induced antibodies compared to in-house and commercially available single-antigen ELISA systems.

  14. ABAP: antibody-based assay for peptidylarginine deiminase activity.

    Science.gov (United States)

    Zendman, Albert J W; Raijmakers, Reinout; Nijenhuis, Suzanne; Vossenaar, Erik R; Tillaart, Marloes van den; Chirivi, Renato G S; Raats, Jos M H; van Venrooij, Walther J; Drijfhout, Jan W; Pruijn, Ger J M

    2007-10-15

    Members of the family of peptidylarginine deiminases (PADs, EC 3.5.3.15) catalyze the posttranslational modification of peptidylarginine into peptidylcitrulline. Citrulline-containing epitopes have been shown to be major and specific targets of autoantibodies produced by rheumatoid arthritis patients. Recently, the citrullination of histone proteins by PAD enzyme was reported to influence gene expression levels. These findings greatly increase the interest in the PAD enzymes and their activities. A few procedures to monitor PAD activity in biological samples have been described previously. However, these assays either have low sensitivity or are rather laborious. Here we describe a reliable and reproducible method for the determination of PAD activity in both purified and crude samples. The method is based on the quantification of PAD-dependent citrullination of peptides, immobilized in microtiter plates, using antibodies that are exclusively reactive with the reaction product(s). Our results demonstrate that this antibody-based assay for PAD activity, called ABAP, is very sensitive and can be applied to monitor PAD activity in biological samples.

  15. Exploring the dynamic range of the kinetic exclusion assay in characterizing antigen-antibody interactions.

    Directory of Open Access Journals (Sweden)

    Christine Bee

    Full Text Available Therapeutic antibodies are often engineered or selected to have high on-target binding affinities that can be challenging to determine precisely by most biophysical methods. Here, we explore the dynamic range of the kinetic exclusion assay (KinExA by exploiting the interactions of an anti-DKK antibody with a panel of DKK antigens as a model system. By tailoring the KinExA to each studied antigen, we obtained apparent equilibrium dissociation constants (K(D values spanning six orders of magnitude, from approximately 100 fM to 100 nM. Using a previously calibrated antibody concentration and working in a suitable concentration range, we show that a single experiment can yield accurate and precise values for both the apparent K(D and the apparent active concentration of the antigen, thereby increasing the information content of an assay and decreasing sample consumption. Orthogonal measurements obtained on Biacore and Octet label-free biosensor platforms further validated our KinExA-derived affinity and active concentration determinations. We obtained excellent agreement in the apparent affinities obtained across platforms and within the KinExA method irrespective of the assay orientation employed or the purity of the recombinant or native antigens.

  16. A fluorescence-based quantitative real-time PCR assay for accurate Pocillopora damicornis species identification

    Science.gov (United States)

    Thomas, Luke; Stat, Michael; Evans, Richard D.; Kennington, W. Jason

    2016-09-01

    Pocillopora damicornis is one of the most extensively studied coral species globally, but high levels of phenotypic plasticity within the genus make species identification based on morphology alone unreliable. As a result, there is a compelling need to develop cheap and time-effective molecular techniques capable of accurately distinguishing P. damicornis from other congeneric species. Here, we develop a fluorescence-based quantitative real-time PCR (qPCR) assay to genotype a single nucleotide polymorphism that accurately distinguishes P. damicornis from other morphologically similar Pocillopora species. We trial the assay across colonies representing multiple Pocillopora species and then apply the assay to screen samples of Pocillopora spp. collected at regional scales along the coastline of Western Australia. This assay offers a cheap and time-effective alternative to Sanger sequencing and has broad applications including studies on gene flow, dispersal, recruitment and physiological thresholds of P. damicornis.

  17. Development of a robust reporter-based assay for the bioactivity determination of anti-VEGF therapeutic antibodies.

    Science.gov (United States)

    Wang, Lan; Xu, Gang-Ling; Gao, Kai; Wilkinson, Jennifer; Zhang, Feng; Yu, Lei; Liu, Chun-Yu; Yu, Chuan-Fei; Wang, Wen-Bo; Li, Meng; Chen, Wei; Fan, Frank; Cong, Mei; Wang, Jun-Zhi

    2016-06-05

    Development of anti-VEGF based biologic agents has been a focus in cancer treatment for the past decades, and several anti-VEGF pharmaceuticals have been already approved for treatment of various medical indications especially in cancer. The first anti-angiogenic agent approved by FDA was bevacizumab (BVZ, trade name Avastin, Genentech/Roche), a humanized anti-VEGF monoclonal antibody. Accurate determination of bioactivity is crucial for the safety and efficacy of therapeutic antibodies. The current method widely used in the lot release and stability test for clinical trial batches of BVZ is anti-proliferation assay using primary human umbilical vein endothelial cells (HUVEC), which is tedious with high assay variations. We describe here the development and preliminary validation of a reporter gene assay (RGA) that is based on an HEK293 cell line stably expressing vascular endothelial growth factor receptor 2 (VEGFR-2), and a luciferase reporter under the control of nuclear factor activated T cell (NFAT) response elements. Our study shows this assay not only to be superior on precision, sensitivity and assay simplicity compared with HUVEC assay, but also applicable to other VEGF-targeted biotherapeutics. These results show for the first time that this new reporter assay, based on the VEGF-VEGFR-NFAT pathway, can be a viable supplement to the HUVEC assay and employed in potency determination of BVZ and other kinds of anti-VEGF antibody-based biotherapeutics. Copyright © 2016. Published by Elsevier B.V.

  18. Development and applications of AlphaScreen-based FcRn binding assay to characterize monoclonal antibodies.

    Science.gov (United States)

    Wu, Qiang; Lee, Ho Young; Wong, Pin Yee; Jiang, Guoying; Gazzano-Santoro, Hélène

    2015-05-01

    IgG antibodies are important pharmaceutical molecules that successfully treat a variety of human diseases. The neonatal Fc receptor (FcRn) interacts with IgG Fc in the CH2-CH3 domain and plays a key role in IgG antibody homeostasis and affects its pharmacokinetic properties. An in vitro FcRn binding assay could be a highly valuable complementary tool to assess IgG antibody pharmacokinetics in IgG engineering and screening during the early optimization stage. In addition, it could be useful in biological characterization studies for antibody minor variants, process optimization, and comparability study at later stages of antibody development. Here we developed a homogeneous AlphaScreen-based FcRn assay to assess the binding of FcRn to IgG antibody in vitro. The assay is found to be accurate, precise, specific, and simple: donor beads loaded with FcRn and acceptor beads loaded with IgG1 mAb1 are mixed together with sample IgG at various dilutions and incubated for 1h before acquiring data with a fluorescence reader. This assay can run up to four samples per plate in 2h, which is time and cost effective compared with other FcRn binding methods such as cell-based fluorescent-activated cell scan and surface plasma resonance. Our data demonstrated that this assay is suitable for assessing the FcRn binding in vitro and provides a platform approach that can be readily applied to various antibodies. Copyright © 2015. Published by Elsevier B.V.

  19. Antibody-Based Assays for Phenotyping of Extracellular Vesicles

    Directory of Open Access Journals (Sweden)

    Lotte Hatting Pugholm

    2015-01-01

    Full Text Available Extracellular vesicles (EVs are a heterogeneous population of membrane-enclosed vesicles. EVs are recognized as important players in cell-to-cell communication and are described to be involved in numerous biological and pathological processes. The fact that EVs are involved in the development and progression of several diseases has formed the basis for the use of EV analysis in a clinical setting. As the interest in EVs has increased immensely, multiple techniques have been developed aiming at characterizing these vesicles. These techniques characterize different features of EVs, like the size distribution, enumeration, protein composition, and the intravesicular cargo (e.g., RNA. This review focuses on techniques that exploit the specificity and sensitivity associated with antibody-based assays to characterize the protein phenotype of EVs. The protein phenotype of EVs can provide information on the functionality of the vesicles and may be used for identification of disease-related biomarkers. Thus, protein profiling of EVs holds great diagnostic and prognostic potential.

  20. Assay for the specificity of monoclonal antibodies in crossed immunoelectrophoresis

    DEFF Research Database (Denmark)

    Skjødt, K; Schou, C; Koch, C

    1984-01-01

    A method is described based on crossed immunoelectrophoresis of a complex antigen mixture in agarose gel followed by incubation of the gel with the monoclonal antibody. The bound monoclonal antibody is detected by the use of a secondary enzyme-labelled antibody. Using this technique we have been...... I molecules. In other experiments using the same technique we demonstrated the reaction of a monoclonal antibody specific for chicken Ig light chains. Udgivelsesdato: 1984-Aug-3...

  1. ELISPOT Assay for Measurement of Antigen-Specific and Polyclonal Antibody Responses.

    Science.gov (United States)

    Lycke, Nils; Coico, Richard

    2015-02-02

    The enzyme-linked immunospot (ELISPOT) assay for detection of antigen-specific and polyclonal antibody responses by single antibody-secreting cells has become the method of choice due to its cell-based quantitative value. Antigen stability and specificity and the diversity of antigens that can be used in the assay have contributed to the translational application of ELISPOT as demonstrated by many FDA-approved clinical tests that employ this technique. In addition, the ELISPOT assay can be used to detect two antigenically different secreted antibodies simultaneously by two-color analysis and offers the unique possibility of quantifying the number of antibody molecules secreted per cell.

  2. Multicentre comparison of a diagnostic assay: Aquaporin-4 antibodies in neuromyelitis optica

    NARCIS (Netherlands)

    P. Waters (Patrick); M. Reindl (Markus); A. Saiz (Albert Abe); K. Schanda (Kathrin); F. Tuller (Friederike); V. Kral (Vlastimil); P. Nytrova (Petra); O. Sobek (Ondrej); H.H. Nielsen (Helle Hvilsted); T. Barington (Torben); S.T. Lillevang (Søren T.); Z. Illes (Zsolt); K. Rentzsch (Kristin); A. Berthele (Achim); T. Berki (Tímea); L. Granieri; A. Bertolotto (Antonio); B. Giometto; L. Zuliani (Luigi); D. Hamann (Dörte); J.L. Van Pelt (Joost L.); R.Q. Hintzen (Rogier); R. Höftberger (Romana); C. Costa (Carme); M. Comabella (Manuel); X. Montalban (Xavier); M. Tintoré; A. Siva (Aksel); A. Altintas (Ayse); G. Deniz (Gunnur); M. Woodhall (Mark); J. Palace (Jacqueline); F. Paul (Friedemann); H.P. Hartung; O. Aktas (Orhan); S. Jarius (Sven); B. Wildemann (Brigitte); C. Vedeler (Christian); A. Ruiz (Anne); M.I. Leite (M. Isabel); P. Trillenberg (Peter); M. Probst (Monika); S. Saschenbrecker (Sandra); A.J.P.E. Vincent (Arnoud); R. Marignier (Romain)

    2016-01-01

    textabstractObjective Antibodies to cell surface central nervous system proteins help to diagnose conditions which often respond to immunotherapies. The assessment of antibody assays needs to reflect their clinical utility. We report the results of a multicentre study of aquaporin (AQP) 4 antibody (

  3. An accurate assay for HCV based on real-time fluorescence detection of isothermal RNA amplification.

    Science.gov (United States)

    Wu, Xuping; Wang, Jianfang; Song, Jinyun; Li, Jiayan; Yang, Yongfeng

    2016-09-01

    Hepatitis C virus (HCV) is one of the common reasons of liver fibrosis and hepatocellular carcinoma (HCC). Early, rapid and accurate HCV RNA detection is important to prevent and control liver disease. A simultaneous amplification and testing (SAT) assay, which is based on isothermal amplification of RNA and real-time fluorescence detection, was designed to optimize routine HCV RNA detection. In this study, HCV RNA and an internal control (IC) were amplified and analyzed simultaneously by SAT assay and detection of fluorescence using routine real-time PCR equipment. The assay detected as few as 10 copies of HCV RNA transcripts. We tested 705 serum samples with SAT, among which 96.4% (680/705) showed consistent results compared with routine real-time PCR. About 92% (23/25) discordant samples were confirmed to be same results as SAT-HCV by using a second real-time PCR. The sensitivity and specificity of SAT-HCV assay were 99.6% (461/463) and 100% (242/242), respectively. In conclusion, the SAT assay is an accurate test with a high specificity and sensitivity which may increase the detection rate of HCV. It is therefore a promising tool to diagnose HCV infection.

  4. The line blot assay: problems with titrating first and second antibodies for Western blot and immunohistochemistry assays?

    Science.gov (United States)

    Rojas-Espinosa, O; Silva-Miranda, M; Wek-Rodriguez, K; Arce-Paredes, P

    2006-01-01

    We describe a technique designed to assess the optimal dilution of primary and secondary antibodies, to be used in Western blot, dot blot, the multi-antigen print immunoassay (MAPIA) and immunohistochemistry assays. The method that we call "line blot" is not an alternative but a practical, complementary tool for the above techniques that assures definitive results are obtained from single assays, so there is no need to repeat the assay. As with most immunoenzymatic assays, the line blot assay is very sensitive, allowing the detection of absolute amounts of antigen as low as 2.5 ng in the 0.5 cm-long segment line (see Results), depending on the strength of the secondary, enzyme-labelled antibody.

  5. Validation of a monoclonal antibody-based immunofluorescent assay to detect Burkholderia pseudomallei in blood cultures.

    Science.gov (United States)

    Dulsuk, Adul; Paksanont, Suporn; Sangchankoom, Adisak; Ekchariyawat, Peeraya; Phunpang, Rungnapa; Jutrakul, Yaowaruk; Chantratita, Narisara; West, T Eoin

    2017-01-22

    Identification of Burkholderia pseudomallei, the cause of melioidosis, using routine methods takes several days. Use of a monoclonal antibody-based immunofluorescent assay (IFA) on positive blood cultures may speed diagnosis. We tested the diagnostic accuracy of the IFA on 545 blood cultures positive for Gram-negative organisms at Udon Thani Hospital, Thailand, between June 2015 and August 2016. Sensitivity of the IFA was 100% and specificity was 99.6%. The median decrease in time to pathogen identification between the IFA result and routine methods was 28 h (IQR 25-51), p<0.0001. The IFA accurately expedites the diagnosis of melioidosis. © The Author 2017. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene.

  6. A focus reduction neutralization assay for hepatitis C virus neutralizing antibodies

    Directory of Open Access Journals (Sweden)

    Wychowski Czeslaw

    2007-03-01

    Full Text Available Abstract Background/Aim The role of humoral immunity in hepatitis C virus (HCV infection is poorly understood. Nevertheless, there is increasing interest in characterizing the neutralizing antibodies in the serum of HCV-infected patients. Focus reduction assays have been widely used to evaluate neutralizing antibody responses against a range of non-cytopathic viruses. Based on the recent development of a HCV cell culture system using the genotype 2 JFH-1-strain, we developed a focus reduction assay for HCV-neutralizing antibodies. Methods The focus reduction assay was based on a standard microneutralization assay in which immunostained foci on tissue culture plates are counted. The neutralizing anti-HCV antibodies titers of purified serum immunoglobulin samples from seventy-seven individuals were determined using a 50% focus reduction neutralization assay. Each titer was determined as the log value of the reciprocal antibody dilution that reduced the number of viral foci by 50%. IgG antibodies were first purified from each serum in order to avoid the facilitating effect of HDL on HCV entry. Results The assay's cut-off using an ELISA and RNA HCV-negative samples was found to be 1.25 log, corresponding to a dilution of 1:18. The assay was compared with a commercial HCV ELISA and exhibited specificity and sensitivity values of 100% and 96.5%, respectively, and good reproducibility (with intra-assay and inter-assay coefficients of variation of 6.7% and 12.6%, respectively. The assay did not show any cross-reactivity with anti-HIV, anti-HBs or heterophile antibody-positive samples. The neutralizing antibodies titers were 2.13 log (1:134 for homologous samples from HCV genotype 2 infected patients harboring the same genotype as JFH-1 and 1.93 log (1:85 for heterologous samples from patients infected by genotypes other than type 2. These results confirm the presence of broadly cross-neutralizing antibodies already reported using the HCV pseudoparticles

  7. A Broadly Applicable Assay for Rapidly and Accurately Quantifying DNA Surface Coverage on Diverse Particles.

    Science.gov (United States)

    Yu, Haixiang; Xu, Xiaowen; Liang, Pingping; Loh, Kang Yong; Guntupalli, Bhargav; Roncancio, Daniel; Xiao, Yi

    2017-04-19

    DNA-modified particles are used extensively for applications in sensing, material science, and molecular biology. The performance of such DNA-modified particles is greatly dependent on the degree of surface coverage, but existing methods for quantitation can only be employed for certain particle compositions and/or conjugation chemistries. We have developed a simple and broadly applicable exonuclease III (Exo III) digestion assay based on the cleavage of phosphodiester bonds-a universal feature of DNA-modified particles-to accurately quantify DNA probe surface coverage on diverse, commonly used particles of different compositions, conjugation chemistries, and sizes. Our assay utilizes particle-conjugated, fluorophore-labeled probes that incorporate two abasic sites; these probes are hybridized to a complementary DNA (cDNA) strand, and quantitation is achieved via cleavage and digestion of surface-bound probe DNA via Exo III's apurinic endonucleolytic and exonucleolytic activities. The presence of the two abasic sites in the probe greatly speeds up the enzymatic reaction without altering the packing density of the probes on the particles. Probe digestion releases a signal-generating fluorophore and liberates the intact cDNA strand to start a new cycle of hybridization and digestion, until all fluorophore tags have been released. Since the molar ratio of fluorophore to immobilized DNA is 1:1, DNA surface coverage can be determined accurately based on the complete release of fluorophores. Our method delivers accurate, rapid, and reproducible quantitation of thiolated DNA on the surface of gold nanoparticles, and also performs equally well with other conjugation chemistries, substrates, and particle sizes, and thus offers a broadly useful assay for quantitation of DNA surface coverage.

  8. Homogeneous plate based antibody internalization assay using pH sensor fluorescent dye.

    Science.gov (United States)

    Nath, Nidhi; Godat, Becky; Zimprich, Chad; Dwight, Stephen J; Corona, Cesear; McDougall, Mark; Urh, Marjeta

    2016-04-01

    Receptor-mediated antibody internalization is a key mechanism underlying several anti-cancer antibody therapeutics. Delivering highly toxic drugs to cancer cells, as in the case of antibody drug conjugates (ADCs), efficient removal of surface receptors from cancer cells and changing the pharmacokinetics profile of the antibody drugs are some of key ways that internalization impacts the therapeutic efficacy of the antibodies. Over the years, several techniques have been used to study antibody internalization including radiolabels, fluorescent microscopy, flow cytometry and cellular toxicity assays. While these methods allow analysis of internalization, they have limitations including a multistep process and limited throughput and are generally endpoint assays. Here, we present a new homogeneous method that enables time and concentration dependent measurements of antibody internalization. The method uses a new hydrophilic and bright pH sensor dye (pHAb dye), which is not fluorescent at neutral pH but becomes highly fluorescent at acidic pH. For receptor mediated antibody internalization studies, antibodies against receptors are conjugated with the pHAb dye and incubated with the cells expressing the receptors. Upon binding to the receptor, the dyes conjugated to the antibody are not fluorescent because of the neutral pH of the media, but upon internalization and trafficking into endosomal and lysosomal vesicles the pH drops and dyes become fluorescent. The enabling attributes of the pHAb dyes are the hydrophilic nature to minimize antibody aggregation and bright fluorescence at acidic pH which allows development of simple plate based assays using a fluorescent reader. Using two different therapeutic antibodies--Trastuzumab (anti-HER2) and Cetuximab (anti-EGFR)--we show labeling with pHAb dye using amine and thiol chemistries and impact of chemistry and dye to antibody ration on internalization. We finally present two new approaches using the pHAb dye, which will be

  9. Comparison of Three Enzyme-Linked Immunosorbent Assays for Detection of Immunoglobulin G Antibodies to Tetanus Toxoid with Reference Standards and the Impact on Clinical Practice▿

    OpenAIRE

    van Hoeven, Karen H.; Dale, Connie; Foster, Phil; Body, Barbara

    2008-01-01

    Accurate determination of the concentrations of immunoglobulin G (IgG) antibody to tetanus toxoid is important in order to evaluate the immunogenicity of tetanus toxoid vaccines, determine immune competence in individual patients, and measure the prevalence of immunity in populations. The performance of three commercially available enzyme-linked immunosorbent assays (ELISAs) for IgG antibodies to tetanus toxoid were evaluated. Serially diluted NIBSC 76/589 and TE-3 human tetanus IgG immunoglo...

  10. Emerging Technologies and Generic Assays for the Detection of Anti-Drug Antibodies

    OpenAIRE

    PARTRIDGE, MICHAEL A.; Shobha Purushothama; Chinnasamy Elango; Yanmei Lu

    2016-01-01

    Anti-drug antibodies induced by biologic therapeutics often impact drug pharmacokinetics, pharmacodynamics response, clinical efficacy, and patient safety. It is critical to assess the immunogenicity risk of potential biotherapeutics in producing neutralizing and nonneutralizing anti-drug antibodies, especially in clinical phases of drug development. Different assay methodologies have been used to detect all anti-drug antibodies, including ELISA, radioimmunoassay, surface plasmon resonance, a...

  11. Enzyme-linked immunosorbent assay for detection of streptolysin O antibodies.

    OpenAIRE

    Reitano, M; Pisano, M. A.; Eriquez, L A; D'Amato, R F

    1986-01-01

    An enzyme-linked immumosorbent assay (ELISA), based upon the detection of streptolysin O antibodies in human sera, was developed. Disposable polystyrene tubes, sensitized with streptolysin O antigen, were used as the test vehicles. Corresponding antibodies, present in test sera, were detected by binding of the antibodies to goat anti-human immunoglobulin G conjugated to horseradish peroxidase. Demonstration of bound conjugate was accomplished by monitoring peroxidase activity spectrophotometr...

  12. Enzyme-linked immunosorbent assay antibody responses to a temperature-sensitive mutant of Pseudomonas aeruginosa.

    OpenAIRE

    Sordelli, D. O.; Rojas, R A; Cerquetti, M C; Hooke, A M; Degnan, P J; Bellanti, J A

    1985-01-01

    The serum immunoglobulin G and M responses induced by immunization of mice with temperature-sensitive mutant A/10/25 of Pseudomonas aeruginosa were evaluated by enzyme-linked immunosorbent assay. These antibody responses were immunotype specific, and the immunoglobulin G antibody level, although low, was still significant by day 52 after vaccination.

  13. Detection of infliximab levels and anti-infliximab antibodies : a comparison of three different assays

    NARCIS (Netherlands)

    Casteele, N. Vande; Buurman, D. J.; Sturkenboom, M. G. G.; Kleibeuker, J. H.; Vermeire, S.; Rispens, T.; van der Kleij, D.; Gils, A.; Dijkstra, G.

    2012-01-01

    Background Formation of antibodies to infliximab (ATI) inversely correlates with functional drug levels and clinical outcome. Comparison of drug levels and anti-drug antibody monitoring is hampered by lack of standardisation. Aim To determine the correlation between three different assays for measur

  14. A versatile assay for the accurate, time-resolved determination of cellular viability.

    Science.gov (United States)

    Amano, Toyoki; Hirasawa, Ken ichi; O'Donohue, Michael J; Pernolle, Jean Claude; Shioi, Yuzo

    2003-03-01

    A convenient and versatile method for the accurate, time-resolved determination of cellular viability has been developed. The conventional viability indicator fluorescein diacetate (FDA), which is converted to the fluorescent compound fluorescein in living cells, was employed as a viability probe. Fluorescence emission from cells was measured using a spectrofluorimeter equipped with a magnetic stirrer. Using this assay cell suspensions exhibiting densities in the range 0.5 x 10(5) to 2.0 x 10(5) cells displayed a linear response when FDA concentrations less than 12 micro M were employed. To calibrate the method, viability standards were elaborated using different proportions of living and dead cells, and a correlation coefficient for the viability of tobacco BY-2 suspensions was calculated as 0.998. This viability assay was also found to be applicable to Chlamydomonas reinhardtii and Arabidopsis thaliana cultured cells. Using this cell viability assay, kinetic analyses of cell death could be performed. Using the proteinaceous elicitor from Phytophthora cryptogea, cryptogein, to induce cell death in tobacco cell suspensions, values for the maximum velocity of death induction rate (V(max)) and the LD50 (half-maximal velocity or k(1/2)) were calculated as 17.2 (% death/h) and 65 nM, respectively.

  15. Solid phase radioimmunoassay using labelled antibodies: a conceptual framework for designing assays

    Energy Technology Data Exchange (ETDEWEB)

    Kalmakoff, J.; Parkinson, A.J.; Crawford, A.M.; Williams, B.R.

    1977-01-01

    A simple theoretical model for the antigen-antibody reaction is presented and used to evaluate the optimum conditions for designing solid phase radioimmunoassay (RIA) using labelled antibodies. Both theoretical and experimental data are presented, using a wide variety of antigens and their corresponding antibodies. The types of RIA described include the direct, the indirect, and sandwich assays for detecting either antigen or antibody. The experimental results confirm in a semiquantitative manner that the greatest sensitivity of the RIA is achieved when the smallest amount of labelled antibody is used, that whenever possible the antigen/antibody ratio should be greater than unity (greater than 1), and that the formation of the antigen-antibody complex is dependent on the mass action effect.

  16. Switching assay as a novel approach for specific antigen- antibody interaction analysis using magnetic nanoparticles

    Science.gov (United States)

    Parr, M.; Illarionov, R.; Marchenko, Y.; Yakovleva, L.; Nikolaev, B.; Ischenko, A.; Shevtsov, M.

    2016-08-01

    Switching assay was applied for the detection of antigen-antibody interaction between 70-kDa heat shock protein (Hsp70) and anti-Hsp70 monoclonal antibodies in water solutions using conjugates with magnetic iron oxide nanoparticles (MNPs). Hsp70 is a ubiquitous intracellular protein that plays a crucial role in cancerogenesis and many other pathologies. Detection of the Hsp70 level in the biological fluids might have a prognostic and diagnostic value in clinic. The developed switch assay for the detection of Hsp70 demonstrated high sensitivity for antigen-antibody interaction analysis thus proving its potential for further preclinical and clinical studies.

  17. COMPARISONS OF ELISA AND WESTERN BLOT ASSAYS FOR DETECTION OF CRYPTOSPORIDIUM ANTIBODY

    Science.gov (United States)

    A seroprevalence survey was conducted using ELISA and Western blot (WB) assays for antibody to three Cryptosporidium antigens on 380 blood donors in Jackson County, Oregon. The purpose was to determine if either assay could detect serological evidence of an outbreak which occurre...

  18. Indirect ELISA and indirect immunofluorescent antibody assay for detecting the antibody against murine norovirus S7 in mice.

    Science.gov (United States)

    Kitagawa, Yota; Tohya, Yukinobu; Ike, Fumio; Kajita, Ayako; Park, Sang-Jin; Ishii, Yoshiyuki; Kyuwa, Shigeru; Yoshikawa, Yasuhiro

    2010-01-01

    To evaluate murine norovirus (MNV) infection in laboratory mice, we attempted to develop an enzyme-linked immunosorbent assay (ELISA) system and an indirect immunofluorescent antibody (IFA) assay for detecting the anti-MNV-S7 antibody in mice. MNV-S7, which was isolated in Japan, was used in both assays. The antigen for ELISA was prepared by ultracentrifugation of culture supernatants of RAW 264 cells infected with MNV-S7. Positive sera were obtained from 6-week-old, female C57BL/6JJcl mice inoculated orally with MNV-S7. IFA against infected RAW 264 cells was able to discriminate positive sera from negative sera. Indirect ELISA was performed using 96-well ELISA plates coated with formalin-treated MNV-S7 antigen. In this ELISA system, mouse sera obtained 2 weeks after infection or later showed significantly high OD values and were judged positive. An equal level of anti-MNV-S7 antibody response was observed in BALB/cAJcl, C57BL/6JJcl, DBA/2JJcl, and Jcl:ICR mice; whereas, C3H/HeJJcl mice demonstrated slightly lower antibody production 4 weeks after infection. We also used this ELISA system to evaluate 77 murine serum samples obtained from 15 conventional mouse rooms in research facilities in Japan and found that approximately half of the serum samples contained antibody to MNV-S7. We found that some serum samples were negative for antibodies to mouse hepatitis virus and Mycoplasma pulmonis but positive for antibody to MNV-S7. The results suggest that the MNV infection is more prevalent than other infections such as mouse hepatitis virus and Mycoplasma pulmonis in conventional mouse colonies in Japan, as is the case in other areas of the world.

  19. Dye Labelled Monoclonal Antibody Assay for Detection of Toxic Shock Syndrome Toxin -1 from Staphylococcus Aureus

    Directory of Open Access Journals (Sweden)

    V Javid Khojasteh

    2011-12-01

    Full Text Available Objective: The aim of study was to develop a rapid assay, dye labelled monoclonal antibody assay (DLMAA, using non-radioactive organic synthetic dyes for identification of Toxic Shock Syndrome Toxin-1 (TSST-1 producing strains of Staphylococcus aureus.Materials and Methods: The assay protocol required only two simple steps; addition of TSST-1 antigen to a nitrocellulose membrane and then adding a colloidal dye labelled antibody (D/A suspension detection reagent.Results: The sensitivity and specificity of the assay was determined relative to positive and negative strains compared to an ELISA assay. Overall 100% agreement was found between both assays. The sensitivity for detection of TSST-1 was 30 ng.Conclusion: The DLMAA did not require handling and disposal of radioactive materials. It is a rapid qualitative technique for detection of TSST-1 toxin at room temperature within a short time.

  20. A rapid and convenient dot-immunobinding assay for chicken egg-yolk antibodies

    Institute of Scientific and Technical Information of China (English)

    GUANG PING RUAN; LI MA; XIN SHENG YAO; QIAN WEN; HONG YUN ZOU; WEI LUO; XIAO NING WANG

    2006-01-01

    The dot-immunobinding assay was applied to investigate the characteristics of chicken egg yolk antibodies. This method of assay was proved to be a rapid and simple method to demonstrate and characterize the egg-yolk antibody IgY in comparison with the traditional ELISA assay. By using the BandScan software, the gray scale value of dots and the background could be determined. According to the intensity of dots (gray scale value) compared to the standard sample of 10 μg, how much IgY remained can be determined in a shorter time.

  1. Validation of western blot for Histoplasma capsulatum antibody detection assay.

    Science.gov (United States)

    Almeida, Marcos de Abreu; Pizzini, Cláudia Vera; Damasceno, Lisandra Serra; Muniz, Mauro de Medeiros; Almeida-Paes, Rodrigo; Peralta, Regina Helena Saramago; Peralta, José Mauro; Oliveira, Raquel de Vasconcelos Carvalhaes; Vizzoni, Alexandre Gomes; de Andrade, Carla Lourenço Tavares; Zancopé-Oliveira, Rosely Maria

    2016-02-24

    Histoplasmosis is worldwide systemic mycoses caused by the dimorphic fungus Histoplasma capsulatum. The isolation and identification of H. capsulatum in culture is the reference test for histoplasmosis diagnosis confirmation. However, in the absence of it, serology has been used as a presumptive diagnosis through antibody and antigen detection. The purpose of the present study was to validate an immunoassay method (western blot) for antibodies detection in the diagnosis of histoplasmosis. To validate the western blot (WB) a study was conducted using 118 serum samples from patients with histoplasmosis and 118 serum controls collected from January 2000 to December 2013 in residents of the Rio de Janeiro State, Brazil. Diagnostic validation parameters were calculated based on the categorization of results obtained in a 2 × 2 table and subjected to statistical analysis. In addition, the viability of deglycosylated histoplasmin antigen (ptHMIN) onto nitrocellulose membranes previously sensitized was evaluated during the same period. The WB test showed sensitivity of 94.9 %, specificity of 94.1 %, positive predictive value of 94.1 %, negative predictive value of 94.9 %, accuracy of 94.5 %, and almost perfect precision. Besides, the strips have proved to be viable for using at least 5 years after ptHMIN antigen sensitization. Western blot test using ptHMIN provides sensitive, specific, and faster results. Therefore, could be considered a useful tool in the diagnosis of histoplasmosis being used by public health system, even in situations where laboratory facilities are relatively limited.

  2. Radiometric immunosorbent assay for the detection of anti-hormone-binding protein antibodies

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, E.A.; Dame, M.C.; DeLuca, H.F.

    1986-02-15

    A radiometric immunosorbent assay (RISA) for the detection of monoclonal antibodies to hormone-binding proteins has been developed. The assay involves incubating hybridoma supernatants in microtiter wells that have been coated with goat anti-mouse IgG antibodies. Any mouse IgG in the test supernatant is thus specifically retained in the wells. Radioactive ligand-binding protein complexes are then incubated in the wells. The presence of anti-binding protein antibodies in the supernatant is indicated by specific retention of radioactive ligand-binding protein complexes in the wells. Crude antigen preparations, such as tissue homogenates, can be used to detect antibodies. The assay is capable of detecting antibody at concentrations 20 ng/ml (approx. 100 pM IgG). The RISA has been used successfully to screen for monoclonal antibodies to the intracellular receptor for 1,25-dihydroxyvitamin D/sub 3/ and should be useful for the detection of antibodies to ligand-binding proteins in general.

  3. Quantum dot-linked immunosorbent assay (QLISA) using orientation-directed antibodies.

    Science.gov (United States)

    Suzuki, Miho; Udaka, Hikari; Fukuda, Takeshi

    2017-09-05

    An approach similar to the enzyme-linked immunosorbent assay (ELISA), with the advantage of saving time and effort but exhibiting high performance, was developed using orientation-directed half-part antibodies immobilized on CdSe/ZnS quantum dots. ELISA is a widely accepted assay used to detect the presence of a target substance. However, it takes time to quantify the target with specificity and sensitivity owing to signal amplification. In this study, CdSe/ZnS quantum dots are introduced as bright and photobleaching-tolerant fluorescent materials. Since hydrophilic surface coating of quantum dots rendered biocompatibility and functional groups for chemical reactions, the quantum dots were modified with half-sized antibodies after partial reduction. The half-sized antibody could be bound to a quantum dot through a unique thiol site to properly display the recognition domain for the core process of ELISA, which is an antigen-antibody interaction. The reducing conditions were investigated to generate efficient conjugates of quantum dots and half-sized antibodies. This was applied to IL-6 detection, as the quantification of IL-6 is significant owing to its close relationships with various biomedical phenomena that cause different diseases. An ELISA-like assay with CdSe/ZnS quantum dot institution (QLISA; Quantum dot-linked immunosorbent assay) was developed to detect 0.05ng/mL IL-6, which makes it sufficiently sensitive as an immunosorbent assay. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. A rapid assay for circulating anti-glomerular basement membrane antibodies in Goodpasture syndrome.

    Science.gov (United States)

    Saxena, R; Isaksson, B; Bygren, P; Wieslander, J

    1989-03-10

    A rapid ELISA for the detection of circulating anti-glomerular basement membrane antibodies in Goodpasture syndrome is described. The specificity of the test was shown to be highly dependent on the antigens used. Using the purified Goodpasture antigen it was possible to shorten the incubation times to 10 min in a routine assay using alkaline phosphatase-labeled second antibodies and the total assay was complete in 30 min. 200 reference sera, 500 sera from patients with various types of glomerulonephritis and 32 sera from patients with Goodpasture syndrome were analyzed by this rapid assay. The assay was able to discriminate between Goodpasture syndrome and other forms of glomerulonephritis. Using enzyme amplification it was possible to further shorten the incubation times to 1 min and the total time of the assay to 6 min.

  5. Validation of a Flow Cytometry Based Binding Assay for Evaluation of Monoclonal Antibody Recognizing EGF Receptor

    Science.gov (United States)

    Cedeño-Arias, Mercedes; Sánchez-Ramírez, Javier; Blanco-Santana, Rancés; Rengifo-Calzado, Enrique

    2011-01-01

    An ideal test used to characterize a product must be appropriate for the measurement of product quality, manufacturing consistency, product stability, and comparability studies. Flow cytometry has been successfully applied to the examination of antibodies and receptors on membrane surfaces; however, to date, the analytical validation of cytometry based assays is limited. Here we report on the validation of a flow cytometry-based assay used in the evaluation of nimotuzumab binding to cells over-expressing EGFR on cell surface. The assay was validated by examining, assay robustness, specificity, repeatability and intermediate precision. The assay was highly specific, robust for all studied factors except for cell fixation with 1% paraformaldehyde and met criteria for precision with RSD < 2%. In addition the assay has stability-indicating properties evidenced by the ability to detect changes in mAb degraded samples. Most importantly, the assay demonstrated to be useful for its intended use. PMID:21886904

  6. Identification of Haemophilus influenzae type b by a monoclonal antibody coagglutination assay.

    OpenAIRE

    Hamel, J.; Brodeur, B R; Belmaaza, A; Montplaisir, S; Musser, J M; Selander, R K

    1987-01-01

    A coagglutination assay using monoclonal antibody is described for the identification of Haemophilus influenzae type b. An immunoglobulin G2a monoclonal antibody, Hb-2, directed against a serotype-specific outer membrane protein of H. influenzae type b was adsorbed to Staphylococcus aureus Cowan 1 cells. In a dot enzyme immunoassay, Hb-2 reacted with 453 of 455 H. influenzae type b isolates and did not react with H. influenzae of other serotypes, untypeable H. influenzae strains, or other bac...

  7. Screening a hybridoma producing a specific monoclonal antibody to HLA-A24+Bw4 antigen by cytotoxicity inhibition assay.

    Science.gov (United States)

    Hiroishi, S; Kaneko, T; Arita, J

    1987-02-01

    A hybridoma secreting a monoclonal antibody (Tsa-1, IgG3) reacting specifically to HLA-A24+Bw4 was screened by cytotoxicity inhibition assay and micrototoxicity test. The R value of the antibody was 0.843.

  8. Standardization of the antibody-dependent respiratory burst assay with human neutrophils and Plasmodium falciparum malaria.

    Science.gov (United States)

    Llewellyn, David; Miura, Kazutoyo; Fay, Michael P; Williams, Andrew R; Murungi, Linda M; Shi, Jianguo; Hodgson, Susanne H; Douglas, Alexander D; Osier, Faith H; Fairhurst, Rick M; Diakite, Mahamadou; Pleass, Richard J; Long, Carole A; Draper, Simon J

    2015-09-16

    The assessment of naturally-acquired and vaccine-induced immunity to blood-stage Plasmodium falciparum malaria is of long-standing interest. However, the field has suffered from a paucity of in vitro assays that reproducibly measure the anti-parasitic activity induced by antibodies in conjunction with immune cells. Here we optimize the antibody-dependent respiratory burst (ADRB) assay, which assesses the ability of antibodies to activate the release of reactive oxygen species from human neutrophils in response to P. falciparum blood-stage parasites. We focus particularly on assay parameters affecting serum preparation and concentration, and importantly assess reproducibility. Our standardized protocol involves testing each serum sample in singlicate with three independent neutrophil donors, and indexing responses against a standard positive control of pooled hyper-immune Kenyan sera. The protocol can be used to quickly screen large cohorts of samples from individuals enrolled in immuno-epidemiological studies or clinical vaccine trials, and requires only 6 μL of serum per sample. Using a cohort of 86 samples, we show that malaria-exposed individuals induce higher ADRB activity than malaria-naïve individuals. The development of the ADRB assay complements the use of cell-independent assays in blood-stage malaria, such as the assay of growth inhibitory activity, and provides an important standardized cell-based assay in the field.

  9. Seropositivity rates of water channel protein 4 antibodies compared between a cell-based immunofluorescence assay and an enzyme-linked immunosorbent assay in neuromyelitis optica patients

    Institute of Scientific and Technical Information of China (English)

    Xiaoli Wu; Zhangyuan Liao; Jing Ye; Huiqing Dong; Chaodong Wang; Piu Chan

    2011-01-01

    A total of 66 samples (from 27 cases with neuromyelitis optica, 26 cases with multiple sclerosis, and 13 cases with optic neuritis) were tested for aquaporin-4 antibody by a cell-based immunofluorescence assay and an enzyme-linked immunosorbent assay.The sensitivities and specificities of the two assays were similar.We further analyzed an additional 68 patients and 93 healthy controls using the enzyme-linked immunosorbent assay.A Kappa test showed good consistency between the two methods in terms of detection of anti-aquaporin-4 antibody in the sera of neuromyelitis optica patients.No significant correlations were identified with onset age or disease duration, suggesting that aquaporin-4 antibody is a good marker for neuromyelitis optica.The enzyme-linked immunosorbent assay can be used for quantifying aquaporin-4 antibody concentrations and may be useful to dynamically monitor changes in the levels of aquaporin-4 antibody during disease duration.

  10. Effect of treatment on serum antibody to Hymenolepis nana detected by enzyme-linked immunosorbent assay.

    OpenAIRE

    Castillo, R M; Grados, P; Carcamo, C.; Miranda, E; T Montenegro; Guevara, A.; Gilman, R H

    1991-01-01

    An enzyme-linked immunosorbent assay (ELISA) was developed to measure serum immunoglobulin G antibodies in 65 patients infected with Hymenolepis nana and 30 noninfected patients. Antibody was detected in 51 of 65 (sensitivity, 79%) and 5 of 30 H. nana-negative patients (specificity, 83%). Nine patients infected with H. nana were treated with praziquantel (20 to 25 mg/kg of body weight). Antibody disappeared from the sera at 90 days in six patients, five of whom had eliminated H. nana. Antibod...

  11. Quantitative bioanalysis of antibody-conjugated payload in monkey plasma using a hybrid immuno-capture LC-MS/MS approach: Assay development, validation, and a case study.

    Science.gov (United States)

    Liu, Ang; Kozhich, Alexander; Passmore, David; Gu, Huidong; Wong, Richard; Zambito, Frank; Rangan, Vangipuram S; Myler, Heather; Aubry, Anne-Françoise; Arnold, Mark E; Wang, Jian

    2015-10-01

    Antibody drug conjugates (ADCs) are complex molecules composed of two pharmacologically distinct components, the cytotoxic payload and the antibody. The measurement of the payload molecules that are attached to the antibody in vivo is important for the evaluation of the safety and efficacy of ADCs, and can also provide distinct information compared to the antibody-related analytes. However, analyzing the antibody-conjugated payload is challenging and in some cases may not be feasible. The in vivo change in drug antibody ratio (DAR), due to deconjugation, biotransformation or other clearance phenomena, generates unique and additional challenges for ADC analysis in biological samples. Here, we report a novel hybrid approach with immuno-capture of the ADC, payload cleavage by specific enzyme, and LC-MS/MS of the cleaved payload to quantitatively measure the concentration of payload molecules still attached to the antibody via linker in plasma. The ADC reference material used for the calibration curve is not likely to be identical to the ADC measured in study samples due to the change in DAR distribution over the PK time course. The assay clearly demonstrated that there was no bias in the measurement of antibody-conjugated payload for ADC with varying DAR, which thus allowed accurate quantification even when the DAR distribution dynamically changes in vivo. This hybrid assay was fully validated based on a combination of requirements for both chromatographic and ligand binding methods, and was successfully applied to support a GLP safety study in monkeys.

  12. Impact of immunization technology and assay application on antibody performance--a systematic comparative evaluation.

    Directory of Open Access Journals (Sweden)

    Michael C Brown

    Full Text Available Antibodies are quintessential affinity reagents for the investigation and determination of a protein's expression patterns, localization, quantitation, modifications, purification, and functional understanding. Antibodies are typically used in techniques such as Western blot, immunohistochemistry (IHC, and enzyme-linked immunosorbent assays (ELISA, among others. The methods employed to generate antibodies can have a profound impact on their success in any of these applications. We raised antibodies against 10 serum proteins using 3 immunization methods: peptide antigens (3 per protein, DNA prime/protein fragment-boost ("DNA immunization"; 3 per protein, and full length protein. Antibodies thus generated were systematically evaluated using several different assay technologies (ELISA, IHC, and Western blot. Antibodies raised against peptides worked predominantly in applications where the target protein was denatured (57% success in Western blot, 66% success in immunohistochemistry, although 37% of the antibodies thus generated did not work in any of these applications. In contrast, antibodies produced by DNA immunization performed well against both denatured and native targets with a high level of success: 93% success in Western blots, 100% success in immunohistochemistry, and 79% success in ELISA. Importantly, success in one assay method was not predictive of success in another. Immunization with full length protein consistently yielded the best results; however, this method is not typically available for new targets, due to the difficulty of generating full length protein. We conclude that DNA immunization strategies which are not encumbered by the limitations of efficacy (peptides or requirements for full length proteins can be quite successful, particularly when multiple constructs for each protein are used.

  13. Indirect solid-phase immunosorbent assay for detection of arenavirus antigens and antibodies

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, A.P.; Rezapkin, G.V.; Dzagurova, T.K.; Tkachenko, E.A. (Institute of Poliomyelitis anU Viral Encephalities of the U.S.S.R. Academy of Medical Sciences, Moscow)

    1984-05-01

    Indirect enzyme-linked immunosorbent assay (ELISA) and solid phase radioimmunoassay (SPRIA) using either enti-human or anti-mouse IgG labelled with horseradish peroxidase and /sup 125/I, respectively, were developed for the detection of Junin, Machupo, Tacaribe, Amapari, Tamiami, Lassa and LCM arenaviruses. Both methods allow high sensitivity detection of arenavirus antigens and antibodies.

  14. Development of an Enzyme Linked Immunosorbent Assay to Detect Chicken Parvovirus Specific Antibodies

    Science.gov (United States)

    Here we report the development and application of an enzyme linked immunosorbent assay to detect parvovirus-specific antibodies in chicken sera. We used an approach previously described for other parvoviruses to clone and express viral structural proteins in insect cells from recombinant baculovirus...

  15. Safe and Objective Assay of Enterovirus 71 Neutralizing Antibodies via Pseudovirus

    Institute of Scientific and Technical Information of China (English)

    JIN Jun; XU Lin; GUO Shi-jie; SUN Shi-yang; ZHANG Shu; ZHU Chang-lin; KONG Wei; JIANG Chun-lai

    2012-01-01

    Current serum neutralization assays based on the inhibition of the eytopathic effect(Nt-CPE) need to manipulate live viruses,which are time-consuming,labor-intensive,and have the potential exposure to infectious agents,so a safe and objective assay via pseudovirus for the fast and efficient detection of enterovirus 71(EV71 ) neutralizing antibodies was developed.First,we generated EV71 pseudovirus containing firefly luciferase gene in place of the capsid gene P1 in EV71 genome.Vero cells infected with 200 CCID50(50% cell culture infective dose) of EV71 pseudovirus for 24 h were found to have the best performance.Seval sera were measured by EV71 pseudoparticle neutralization assay(Nt-PPN) and the conventional serological method Nt-CPE.Neutralizing antibody titers measured by Nt-PPN and those obtained by Nt-CPE demonstrate a high correlation between the two methods.Overall,the PPN assay represents a valid alternative to conventional serological methods for the evaluation of EV71 neutralizing antibodies.This method can be used for detecting neutralizing antibodies of other picornaviruses,such as hepatitis A virus(HAV) and coxsackievirus 16(CVA16),and make it possible to determine whether there is cross-reactivity between EV71 and CVA16.

  16. Raised tryptase without anaphylaxis or mastocytosis: heterophilic antibody interference in the serum tryptase assay.

    Science.gov (United States)

    Sargur, R; Cowley, D; Murng, S; Wild, G; Green, K; Shrimpton, A; Egner, W

    2011-03-01

    Mast cell tryptase (MCT) is a key diagnostic test for mastocytosis and anaphylaxis. High serum tryptase levels are also one of the risk factors for adverse reaction in venom immunotherapy, yet occasional patients are seen with raised levels in the absence of either diagnosis. False positive results can be due to assay interference by heterophilic antibodies such as rheumatoid factor (RF) and human anti-mouse antibodies (HAMA). We therefore investigated heterophilic antibody interference by rheumatoid factor activity and HAMA as a cause of raised MCT results in the Phadia tryptase assay. Serum samples from 83 patients were assayed for MCT and rheumatoid factor before and after the use of heterophilic antibody blocking tubes (HBT). Samples with more than 17% reduction in MCT with detectable RF were then assayed for HAMA. Fourteen (17%) of the 83 samples with positive RF showed a >17% decrease in mast cell tryptase after HBT blocking. Post-HBT, eight of 14 (57%) reverted from elevated to normal range values with falls of up to 98%. RF levels were also decreased significantly (up to 75%). Only one of the 83 tested was apparently affected by HAMA in the absence of detectable IgM RF. In conclusion, any suspicious MCT result should be checked for heterophilic antibodies to evaluate possible interference. False positive MCT levels can be caused by rheumatoid factor. We suggest a strategy for identifying assay interference, and show that it is essential to incorporate this caveat into guidance for interpretation of MCT results. © 2011 The Authors. Clinical and Experimental Immunology © 2011 British Society for Immunology.

  17. Pregnancy does not affect HIV incidence test results obtained using the BED capture enzyme immunoassay or an antibody avidity assay.

    Directory of Open Access Journals (Sweden)

    Oliver Laeyendecker

    Full Text Available BACKGROUND: Accurate incidence estimates are needed for surveillance of the HIV epidemic. HIV surveillance occurs at maternal-child health clinics, but it is not known if pregnancy affects HIV incidence testing. METHODS: We used the BED capture immunoassay (BED and an antibody avidity assay to test longitudinal samples from 51 HIV-infected Ugandan women infected with subtype A, C, D and intersubtype recombinant HIV who were enrolled in the HIVNET 012 trial (37 baseline samples collected near the time of delivery and 135 follow-up samples collected 3, 4 or 5 years later. Nineteen of 51 women were also pregnant at the time of one or more of the follow-up visits. The BED assay was performed according to the manufacturer's instructions. The avidity assay was performed using a Genetic Systems HIV-1/HIV-2 + O EIA using 0.1M diethylamine as the chaotropic agent. RESULTS: During the HIVNET 012 follow-up study, there was no difference in normalized optical density values (OD-n obtained with the BED assay or in the avidity test results (% when women were pregnant (n = 20 results compared to those obtained when women were not pregnant (n = 115; for BED: p = 0.9, generalized estimating equations model; for avidity: p = 0.7, Wilcoxon rank sum. In addition, BED and avidity results were almost exactly the same in longitudinal samples from the 18 women who were pregnant at only one study visit during the follow-up study (p = 0.6, paired t-test. CONCLUSIONS: These results from 51 Ugandan women suggest that any changes in the antibody response to HIV infection that occur during pregnancy are not sufficient to alter results obtained with the BED and avidity assays. Confirmation with larger studies and with other HIV subtypes is needed.

  18. Effect of treatment on serum antibody to Hymenolepis nana detected by enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Castillo, R M; Grados, P; Carcamo, C; Miranda, E; Montenegro, T; Guevara, A; Gilman, R H

    1991-01-01

    An enzyme-linked immunosorbent assay (ELISA) was developed to measure serum immunoglobulin G antibodies in 65 patients infected with Hymenolepis nana and 30 noninfected patients. Antibody was detected in 51 of 65 (sensitivity, 79%) and 5 of 30 H. nana-negative patients (specificity, 83%). Nine patients infected with H. nana were treated with praziquantel (20 to 25 mg/kg of body weight). Antibody disappeared from the sera at 90 days in six patients, five of whom had eliminated H. nana. Antibody persisted in three patients in whom H. nana infection did not clear after treatment. The H. nana ELISA had a high rate of cross-reactions with sera from patients with cysticercosis (8 of 29 [28%]) and hydatidosis (8 of 23 [35%]). The ELISA for H. nana may be useful for defining the epidemiology of H. nana infections, especially in areas free from cysticercosis and hydatidosis. PMID:2007652

  19. Effect of treatment on serum antibody to Hymenolepis nana detected by enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Castillo, R M; Grados, P; Carcamo, C; Miranda, E; Montenegro, T; Guevara, A; Gilman, R H

    1991-02-01

    An enzyme-linked immunosorbent assay (ELISA) was developed to measure serum immunoglobulin G antibodies in 65 patients infected with Hymenolepis nana and 30 noninfected patients. Antibody was detected in 51 of 65 (sensitivity, 79%) and 5 of 30 H. nana-negative patients (specificity, 83%). Nine patients infected with H. nana were treated with praziquantel (20 to 25 mg/kg of body weight). Antibody disappeared from the sera at 90 days in six patients, five of whom had eliminated H. nana. Antibody persisted in three patients in whom H. nana infection did not clear after treatment. The H. nana ELISA had a high rate of cross-reactions with sera from patients with cysticercosis (8 of 29 [28%]) and hydatidosis (8 of 23 [35%]). The ELISA for H. nana may be useful for defining the epidemiology of H. nana infections, especially in areas free from cysticercosis and hydatidosis.

  20. Comparison of the latex agglutination test with the hemagglutination inhibition test, enzyme-linked immunosorbent assay, and neutralization test for detection of antibodies to rubella virus.

    OpenAIRE

    Meegan, J M; Evans, B. K.; Horstmann, D. M.

    1982-01-01

    The ability of a rapid, latex agglutination test to diagnose rubella infection and to measure immune status was evaluated by comparison with the hemagglutination-inhibition (HAI) test, enzyme-linked immunosorbent assay (ELISA), and the neutralization (NT) test. The latex agglutination test accurately detected serological conversions in 74 pairs of sera representing 21 natural infections and 53 immunizations. The antibody levels of 276 sera from the general population were determined by latex ...

  1. High-throughput immunoturbidimetric assays for in-process determination of polyclonal antibody concentration and functionality in crude samples

    DEFF Research Database (Denmark)

    Bak, Hanne; Kyhse-Andersen, J.; Thomas, O.R.T.

    2007-01-01

    We present fast, simple immunoturbidimetric assays suitable for direct determination of antibody 'concentration' and 'functionality' in crude samples, such as in-process samples taken at various stages during antibody purification. Both assays display excellent linearity and analytical recovery....... The 'functionality' assay displayed concentration dependent sensitivity to interference for ammonium sulphate and Tris(hydroxymethyl)-amino-methane, but was essentially unaffected by all other salts and buffer combinations tested. The immunoturbidimetric assays described here are generically applicable to polyclonal...... antibodies, require only basic laboratory equipment, are robust, fast, cheap, easy to perform, and readily adapted to automation....

  2. Aptamers as a replacement for antibodies in enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Toh, Saw Yi; Citartan, Marimuthu; Gopinath, Subash C B; Tang, Thean-Hock

    2015-02-15

    The application of antibodies in enzyme-linked immunosorbent assay (ELISA) is the basis of this diagnostic technique which is designed to detect a potpourri of complex target molecules such as cell surface antigens, allergens, and food contaminants. However, development of the systematic evolution of Ligands by Exponential Enrichment (SELEX) method, which can generate a nucleic acid-based probe (aptamer) that possess numerous advantages compared to antibodies, offers the possibility of using aptamers as an alternative molecular recognition element in ELISA. Compared to antibodies, aptamers are smaller in size, can be easily modified, are cheaper to produce, and can be generated against a wide array of target molecules. The application of aptamers in ELISA gives rise to an ELISA-derived assay called enzyme-linked apta-sorbent assay (ELASA). As with the ELISA method, ELASA can be used in several different configurations, including direct, indirect, and sandwich assays. This review provides an overview of the strategies involved in aptamer-based ELASA.

  3. Assay interference caused by antibodies reacting with rat kappa light-chain in human sera.

    Science.gov (United States)

    Degn, Søren E; Andersen, Stig Henrik; Jensen, Lisbeth; Thiel, Steffen; Jensenius, Jens C

    2011-09-30

    The enzyme-linked immunosorbent assay (ELISA) and its derivatives are powerful tools used in research, in the clinic, and in many other analytical and quality control settings. In general, ELISAs are robust, reproducible and reliable. However, a number of pitfalls of ELISAs have been described over the years. The issue of rheumatoid factor (RF), autoantibodies against the Fc portion of IgG, is well recognized (yet often forgotten), as are problems arising from heterophilic antibodies induced by external antigens that cross-react with self-antigens. A few years ago focus was on human anti-mouse antibodies (HAMA) concomitant with the increased use of mouse monoclonal antibody therapy, a problem that is now diminishing due to development of humanized antibodies. Issues pertaining to food antigens or environmentally encountered antigens are less recognized. We report a recently encountered example of the latter resulting in interference in a solid-phase sandwich assay. Due to the set-up employing a monoclonal rat IgG for capture and a monoclonal rat IgM for development the interference had to be human antibodies reacting with rat light-chain. Out of 102 Danish Caucasian blood donors we found a prevalence of anti-rat kappa light chain antibodies of close to 40% (39/102, defined as at least 2-fold elevated measurements), with around 6% (6/102) having very high levels (defined as at least 4-fold elevated measurements), yielding significantly higher measurements in the assay designed to measure the complement component MAp19 in serum samples. The interference could be blocked by the addition of rat immunoglobulin to the sample buffer. An individual, who had been followed over time, demonstrated a periodic increase of interfering antibodies, highlighting that it is an independently varying parameter and thereby a variable interference in assays. Our results highlight a major pitfall of potential relevance to many sandwich-type assays, as well as an approach to rectify such

  4. Use of In Vitro Assays to Assess Immunogenicity Risk of Antibody-Based Biotherapeutics

    Science.gov (United States)

    Joubert, Marisa K.; Deshpande, Meghana; Yang, Jane; Reynolds, Helen; Bryson, Christine; Fogg, Mark; Baker, Matthew P.; Herskovitz, Jonathan; Goletz, Theresa J.; Zhou, Lei; Moxness, Michael; Flynn, Gregory C.; Narhi, Linda O.; Jawa, Vibha

    2016-01-01

    An In Vitro Comparative Immunogenicity Assessment (IVCIA) assay was evaluated as a tool for predicting the potential relative immunogenicity of biotherapeutic attributes. Peripheral blood mononuclear cells from up to 50 healthy naïve human donors were monitored up to 8 days for T-cell proliferation, the number of IL-2 or IFN-γ secreting cells, and the concentration of a panel of secreted cytokines. The response in the assay to 10 monoclonal antibodies was found to be in agreement with the clinical immunogenicity, suggesting that the assay might be applied to immunogenicity risk assessment of antibody biotherapeutic attributes. However, the response in the assay is a measure of T-cell functional activity and the alignment with clinical immunogenicity depends on several other factors. The assay was sensitive to sequence variants and could differentiate single point mutations of the same biotherapeutic. Nine mAbs that were highly aggregated by stirring induced a higher response in the assay than the original mAbs before stirring stress, in a manner that did not match the relative T-cell response of the original mAbs. In contrast, mAbs that were glycated by different sugars (galactose, glucose, and mannose) showed little to no increase in response in the assay above the response to the original mAbs before glycation treatment. The assay was also used successfully to assess similarity between multiple lots of the same mAb, both from the same manufacturer and from different manufacturers (biosimilars). A strategy for using the IVCIA assay for immunogenicity risk assessment during the entire lifespan development of biopharmaceuticals is proposed. PMID:27494246

  5. Prevalence of antibodies to type A influenza virus in wild avian species using two serologic assays

    Science.gov (United States)

    Brown, Justin D.; Luttrell, M. Page; Berghaus, Roy D.; Kistler, Whitney; Keeler, Shamus P.; Howey, Andrea; Wilcox, Benjamin; Hall, Jeffrey; Niles, Larry; Dey, Amanda; Knutsen, Gregory; Fritz, Kristen; Stallknecht, David E.

    2010-01-01

    Serologic testing to detect antibodies to avian influenza (AI) virus has been an underused tool for the study of these viruses in wild bird populations, which traditionally has relied on virus isolation and reverse transcriptase-polymerase chain reaction (RT-PCR). In a preliminary study, a recently developed commercial blocking enzyme-linked immunosorbent assay (bELISA) had sensitivity and specificity estimates of 82% and 100%, respectively, for detection of antibodies to AI virus in multiple wild bird species after experimental infection. To further evaluate the efficacy of this commercial bELISA and the agar gel immunodiffusion (AGID) test for AI virus antibody detection in wild birds, we tested 2,249 serum samples collected from 62 wild bird species, representing 10 taxonomic orders. Overall, the bELISA detected 25.4% positive samples, whereas the AGID test detected 14.8%. At the species level, the bELISA detected as many or more positive serum samples than the AGID in all 62 avian species. The majority of positive samples, detected by both assays, were from species that use aquatic habitats, with the highest prevalence from species in the orders Anseriformes and Charadriiformes. Conversely, antibodies to AI virus were rarely detected in the terrestrial species. The serologic data yielded by both assays are consistent with the known epidemiology of AI virus in wild birds and published reports of host range based on virus isolation and RT-PCR. The results of this research are also consistent with the aforementioned study, which evaluated the performance of the bELISA and AGID test on experimental samples. Collectively, the data from these two studies indicate that the bELISA is a more sensitive serologic assay than the AGID test for detecting prior exposure to AI virus in wild birds. Based on these results, the bELISA is a reliable species-independent assay with potentially valuable applications for wild bird AI surveillance.

  6. Prevalence of antibodies to type A influenza virus in wild avian species using two serologic assays

    Science.gov (United States)

    Brown, Justin D.; Luttrell, M. Page; Berghaus, Roy D.; Kistler, Whitney; Keeler, Shamus P.; Howey, Andrea; Wilcox, Benjamin; Hall, Jeffrey; Niles, Larry; Dey, Amanda; Knutsen, Gregory; Fritz, Kristen; Stallknecht, David E.

    2010-01-01

    Serologic testing to detect antibodies to avian influenza (AI) virus has been an underused tool for the study of these viruses in wild bird populations, which traditionally has relied on virus isolation and reverse transcriptase-polymerase chain reaction (RT-PCR). In a preliminary study, a recently developed commercial blocking enzyme-linked immunosorbent assay (bELISA) had sensitivity and specificity estimates of 82% and 100%, respectively, for detection of antibodies to AI virus in multiple wild bird species after experimental infection. To further evaluate the efficacy of this commercial bELISA and the agar gel immunodiffusion (AGID) test for AI virus antibody detection in wild birds, we tested 2,249 serum samples collected from 62 wild bird species, representing 10 taxonomic orders. Overall, the bELISA detected 25.4% positive samples, whereas the AGID test detected 14.8%. At the species level, the bELISA detected as many or more positive serum samples than the AGID in all 62 avian species. The majority of positive samples, detected by both assays, were from species that use aquatic habitats, with the highest prevalence from species in the orders Anseriformes and Charadriiformes. Conversely, antibodies to AI virus were rarely detected in the terrestrial species. The serologic data yielded by both assays are consistent with the known epidemiology of AI virus in wild birds and published reports of host range based on virus isolation and RT-PCR. The results of this research are also consistent with the aforementioned study, which evaluated the performance of the bELISA and AGID test on experimental samples. Collectively, the data from these two studies indicate that the bELISA is a more sensitive serologic assay than the AGID test for detecting prior exposure to AI virus in wild birds. Based on these results, the bELISA is a reliable species-independent assay with potentially valuable applications for wild bird AI surveillance.

  7. Enzyme-linked immunosorbent assay (ELISA) for antibodies against Campylobacter jejuni, and its clinical application.

    Science.gov (United States)

    Walder, M; Forsgren, A

    1982-12-01

    Antibody response to Campylobacter jejuni/coli (CJC) was investigated, using an enzyme-linked immunosorbent assay, ELISA. With a mixture of lipopolysaccharide from two CJC strains as antigen in ELISA, all 24 tested rabbit anti-CJC sera showed high antibody levels. However, only 70% of sera from patients with Campylobacter enteritis demonstrated an antibody response against the combined LPS antigen, using paired sera. In addition, the results obtained suggested non-specific binding of human immunoglobulin. When 24 formalinized whole CJC bacteria were used as antigen in ELISA, all corresponding rabbit antisera reacted with one strain (M 14). Essentially no unspecific binding of human immunoglobulin was obtained. Antibodies were detected in sera from healthy blood donors and at a lower level in sera from children, suggesting early immunization. In 67 enteritis patients with positive stool cultures for CJC, a significantly increased level of IgG antibodies could be detected in single or paired serum samples from 82% of the patients. An IgG titre increase occurred early in the course of infection, suggesting a boosting of an earlier immunization. IgM antibodies could be detected in the same sera in 77% of the patients. Considering both IgG and IgM analyses of the enteritis sera, 94% of the patients were positive in Campylobacter ELISA serology compared with only 5% of healthy controls.

  8. Antibody class capture assay (ACCA) for rubella-specific IgM antibody.

    Science.gov (United States)

    Isaac, M; Payne, R A

    1982-01-01

    Enzyme-linked immunosorbent assays for IgM antirubella were carried out on 1,546 sera, using an IgM capture method with a F (ab')2 conjugate (ACCA). Under the conditions described, sera containing IgM antirubella bound up to 15 times as much enzyme activity as negative specimens. Paired serum specimens from 27 patients, serial serum specimens from 6 patients, and single serum specimens from 15 patients who had had recent rubella were examined by the haemagglutination inhibition test (HAI) in the presence and absence of 2-mercaptoethanol following sucrose density gradient centrifugation (SDGC). ACCA confirmed all the results found with HAI following SDGC. Specimens were examined from ten patients with congenital rubella; ACCA confirmed the results found with both immunofluorescence following SDGC and radioimmunoassay. Pre- and post-vaccination specimens from 123 patients who had been vaccinated against rubella were examined. An IgM response could only be demonstrated in the 57 cases when IgG was absent in the first specimen. The specificity of the assay was confirmed by testing 31 serum specimens from rubella immune patients that also contained rheumatoid factor, 163 serum specimens from patients with acute infections other than rubella, and 12 serum specimens from infants with miscellaneous neonatal abnormalities other than congenital rubella. The ACCA proved a simple, sensitive, and specific test for IgM antirubella and the results compared favourably with those obtained by the SDGC technique.

  9. Development and validation of a homogeneous mobility shift assay for the measurement of infliximab and antibodies-to-infliximab levels in patient serum.

    Science.gov (United States)

    Wang, Shui-Long; Ohrmund, Linda; Hauenstein, Scott; Salbato, Jared; Reddy, Rukmini; Monk, Patrick; Lockton, Steven; Ling, Nicholas; Singh, Sharat

    2012-08-31

    Antibody-based drugs such as infliximab (IFX) are effective for the treatment of inflammatory bowel disease (IBD) and other immune-mediated disorders. The development of antibodies against these drugs may result in unfavorable consequences, including the loss of drug efficacy, hypersensitivity reactions, and other adverse events. Therefore, accurate monitoring of serum drug and anti-drug antibody levels should be an important part of therapy for patients being treated with an antibody-based drug. Current methods for the assessment of anti-drug antibodies and drug levels, involving various bridging ELISA and radioimmunoassay techniques, are limited by their sensitivity, interference, and/or complexity. To overcome these limitations, we have developed a non-radiolabeled homogeneous mobility shift assay (HMSA) to measure the antibodies-to-infliximab (ATI) and IFX levels in serum samples. Full method validation was performed on both the ATI- and IFX-HMSA, and the clinical sample test results were also compared with those obtained from a bridging ELISA method to evaluate the difference in performance between the two assays. Validation of the ATI-HMSA revealed a lower limit of quantitation of 0.012 μg/mL in serum. The linear range of quantitation was 0.029-0.54 μg/mL. The intra- and inter-assay precision was less than 20% of coefficient of variation (CV), and the accuracy (% error) of the assay was less than 20%. In serum samples, ATI as low as 0.036 μg/mL can be measured, even in the presence of 60 μg/mL of IFX in the serum. Sera from 100 healthy subjects were tested to determine the cut point of the assay. ATI-positive samples that had been previously analyzed by using a bridging ELISA from 100 patients were also measured by the new method. There was a high correlation between the two methods for ATI levels (pELISA method. Validation of the mobility shift IFX assay also showed high assay sensitivity, precision and accuracy. The HMSA method may also be applied to

  10. Recent developments in antibody-based assays for the detection of bacterial toxins.

    Science.gov (United States)

    Zhu, Kui; Dietrich, Richard; Didier, Andrea; Doyscher, Dominik; Märtlbauer, Erwin

    2014-04-11

    Considering the urgent demand for rapid and accurate determination of bacterial toxins and the recent promising developments in nanotechnology and microfluidics, this review summarizes new achievements of the past five years. Firstly, bacterial toxins will be categorized according to their antibody binding properties into low and high molecular weight compounds. Secondly, the types of antibodies and new techniques for producing antibodies are discussed, including poly- and mono-clonal antibodies, single-chain variable fragments (scFv), as well as heavy-chain and recombinant antibodies. Thirdly, the use of different nanomaterials, such as gold nanoparticles (AuNPs), magnetic nanoparticles (MNPs), quantum dots (QDs) and carbon nanomaterials (graphene and carbon nanotube), for labeling antibodies and toxins or for readout techniques will be summarized. Fourthly, microscale analysis or minimized devices, for example microfluidics or lab-on-a-chip (LOC), which have attracted increasing attention in combination with immunoassays for the robust detection or point-of-care testing (POCT), will be reviewed. Finally, some new materials and analytical strategies, which might be promising for analyzing toxins in the near future, will be shortly introduced.

  11. Recent Developments in Antibody-Based Assays for the Detection of Bacterial Toxins

    Science.gov (United States)

    Zhu, Kui; Dietrich, Richard; Didier, Andrea; Doyscher, Dominik; Märtlbauer, Erwin

    2014-01-01

    Considering the urgent demand for rapid and accurate determination of bacterial toxins and the recent promising developments in nanotechnology and microfluidics, this review summarizes new achievements of the past five years. Firstly, bacterial toxins will be categorized according to their antibody binding properties into low and high molecular weight compounds. Secondly, the types of antibodies and new techniques for producing antibodies are discussed, including poly- and mono-clonal antibodies, single-chain variable fragments (scFv), as well as heavy-chain and recombinant antibodies. Thirdly, the use of different nanomaterials, such as gold nanoparticles (AuNPs), magnetic nanoparticles (MNPs), quantum dots (QDs) and carbon nanomaterials (graphene and carbon nanotube), for labeling antibodies and toxins or for readout techniques will be summarized. Fourthly, microscale analysis or minimized devices, for example microfluidics or lab-on-a-chip (LOC), which have attracted increasing attention in combination with immunoassays for the robust detection or point-of-care testing (POCT), will be reviewed. Finally, some new materials and analytical strategies, which might be promising for analyzing toxins in the near future, will be shortly introduced. PMID:24732203

  12. Recent Developments in Antibody-Based Assays for the Detection of Bacterial Toxins

    Directory of Open Access Journals (Sweden)

    Kui Zhu

    2014-04-01

    Full Text Available Considering the urgent demand for rapid and accurate determination of bacterial toxins and the recent promising developments in nanotechnology and microfluidics, this review summarizes new achievements of the past five years. Firstly, bacterial toxins will be categorized according to their antibody binding properties into low and high molecular weight compounds. Secondly, the types of antibodies and new techniques for producing antibodies are discussed, including poly- and mono-clonal antibodies, single-chain variable fragments (scFv, as well as heavy-chain and recombinant antibodies. Thirdly, the use of different nanomaterials, such as gold nanoparticles (AuNPs, magnetic nanoparticles (MNPs, quantum dots (QDs and carbon nanomaterials (graphene and carbon nanotube, for labeling antibodies and toxins or for readout techniques will be summarized. Fourthly, microscale analysis or minimized devices, for example microfluidics or lab-on-a-chip (LOC, which have attracted increasing attention in combination with immunoassays for the robust detection or point-of-care testing (POCT, will be reviewed. Finally, some new materials and analytical strategies, which might be promising for analyzing toxins in the near future, will be shortly introduced.

  13. Highly Accurate Antibody Assays for Early and Rapid Detection of Tuberculosis in African and Asian Elephants

    Science.gov (United States)

    Tuberculosis (TB) in elephants is a re-emerging zoonotic disease caused primarily by Mycobacterium tuberculosis. Current methods for screening and diagnosis rely on trunk wash culture, which has serious limitations due to low test sensitivity, slow turn-around time, and variable sample quality. Inn...

  14. Newly established monoclonal antibody diagnostic assays for Schistosoma mansoni direct detection in areas of low endemicity.

    Directory of Open Access Journals (Sweden)

    Rafaella Fortini Queiroz Grenfell

    Full Text Available BACKGROUND: Current available methods for diagnosis of schistosomiasis mansoni lack sufficient sensitivity, which results in underreporting of infectious in areas of low endemicity. METHODOLOGY/PRINCIPAL FINDINGS: We developed three novel diagnostic methodologies for the direct detection of schistosome infection in serum samples. These three new methods were evaluated with positive patients from a low endemicity area in southeast Brazil. The basis of the assay was the production of monoclonal antibodies against the protein backbone of heavily glycosylated Circulating Cathodic Antigen (CCA. The antibodies were also selected for having no specificity to repeating poly-Lewis x units. Assays based on the detection CCA-protein should not encounter a limitation in sensitivity due to a biological background of this particular epitope. Three diagnostic methodologies were developed and validated, (i Immunomagnetic Separation based on improved incubation steps of non-diluted serum, (ii Direct Enzyme-linked Immunosorbent Assay and (iii Fluorescent Microscopy Analysis as a qualitative assay. The two quantitative assays presented high sensitivity (94% and 92%, respectively and specificity (100%, equivalent to the analysis of 3 stool samples and 16 slides by Kato-Katz, showing promising results on the determination of cure. CONCLUSIONS/SIGNIFICANCE: The Immunomagnetic Separation technique showed excellent correlation with parasite burden by Cohen coefficient. The qualitative method detected 47 positive individuals out of 50 with the analysis of 3 slides. This easy-to-do method was capable of discriminating positive from negative cases, even for patients with low parasite burden.

  15. Specific immunoradiometric assay of insulin-like growth factor I with use of monoclonal antibodies

    Energy Technology Data Exchange (ETDEWEB)

    Scott, M.G.; Cuca, G.C.; Petersen, J.R.; Lyle, L.R.; Burleigh, B.D.; Daughaday, W.H.

    1987-11-01

    We identified two monoclonal antibodies that bind spatially distinct epitopes on insulin-like growth factor I (IGF-I). Using these two antibodies, we developed a simultaneous, two-site immunoradiometric assay (IRMA) specific for IGF-I. This IRMA has no detectable cross reactivity with insulin, proinsulin, prolactin, or somatotropin, and less than 2% crossreactivity with IGF-II. The assay response varies linearly with IGF-I concentrations of 0-800 micrograms/L in serum; the detection limit is about 10 micrograms/L. A comparison of 26 IGF-I serum values from the IRMA and from a previously reported IGF-I specific RIA gave a correlation coefficient of 0.96 with no substantial bias (slope = 1.10). IGF-I values for serum, as an aid in assessing growth abnormalities, are easily (only three pipetting steps) obtained in less than 4 h.

  16. Specific immunoradiometric assay of insulin-like growth factor I with use of monoclonal antibodies.

    Science.gov (United States)

    Scott, M G; Cuca, G C; Petersen, J R; Lyle, L R; Burleigh, B D; Daughaday, W H

    1987-11-01

    We identified two monoclonal antibodies that bind spatially distinct epitopes on insulin-like growth factor I (IGF-I). Using these two antibodies, we developed a simultaneous, two-site immunoradiometric assay (IRMA) specific for IGF-I. This IRMA has no detectable cross reactivity with insulin, proinsulin, prolactin, or somatotropin, and less than 2% crossreactivity with IGF-II. The assay response varies linearly with IGF-I concentrations of 0-800 micrograms/L in serum; the detection limit is about 10 micrograms/L. A comparison of 26 IGF-I serum values from the IRMA and from a previously reported IGF-I specific RIA gave a correlation coefficient of 0.96 with no substantial bias (slope = 1.10). IGF-I values for serum, as an aid in assessing growth abnormalities, are easily (only three pipetting steps) obtained in less than 4 h.

  17. HLA antibody detection with solid phase assays: great expectations or expectations too great?

    Science.gov (United States)

    Gebel, H M; Bray, R A

    2014-09-01

    Alloantibodies directed against HLA antigens, are a barrier to long-term solid organ allograft survival. The clinical impact of preformed, donor-directed HLA alloantibodies range from acceptable risk to unequivocal contraindication for organ transplantation. HLA antibodies are key factors that limit patient access to donor organs. Serological methods were once the only approach to identify HLA antigens and antibodies. Limitations in these technologies led to the development of solid phase approaches. In the early 1990s, the development of the polymerase chain reaction enabled DNA-based HLA antigen testing to be performed. By the mid-1990s, microparticle-based technology that utilized flow cytometry for analysis was developed to detect both classes I and II HLA antibodies. These methodologies revolutionized clinical histocompatibility testing. The strengths and weaknesses of these assays are described in detail in this review.

  18. Detection of anti-infliximab antibodies is impacted by antibody titer, infliximab level and IgG4 antibodies: a systematic comparison of three different assays

    Science.gov (United States)

    Afonso, Joana; Lopes, Susana; Gonçalves, Raquel; Caldeira, Paulo; Lago, Paula; Tavares de Sousa, Helena; Ramos, Jaime; Gonçalves, Ana Rita; Ministro, Paula; Rosa, Isadora; Vieira, Ana Isabel; Coelho, Rosa; Tavares, Patrícia; Soares, João; Sousa, Ana Lúcia; Carvalho, Diana; Sousa, Paula; da Silva, João Pereira; Meira, Tânia; Silva Ferreira, Filipa; Dias, Cláudia Camila; Chowers, Yehuda; Ben-Horin, Shomron; Magro, Fernando

    2016-01-01

    Background: There is scant information on the accuracy of different assays used to measure anti-infliximab antibodies (ADAs), especially in the presence of detectable infliximab (IFX). We thus aimed to evaluate and compare three different assays for the detection of IFX and ADAs and to clarify the impact of the presence of circulating IFX on the accuracy of the ADA assays. Methods: Blood samples from 79 ulcerative colitis (UC) patients treated with infliximab were assessed for IFX levels and ADAs using three different assays: an in-house assay and two commercial kits, Immundiagnostik and Theradiag. Sera samples with ADAs and undetectable levels of IFX were spiked with exogenous IFX and analyzed for ADAs. Results: The three assays showed 81–96% agreement for the measured IFX level. However, the in-house assay and Immundiagnostik assays detected ADAs in 34 out of 79 samples, whereas Theradiag only detected ADAs in 24 samples. Samples negative for ADAs with Theradiag, but ADA-positive in both the in-house and Immundiagnostik assays, were positive for IFX or IgG4 ADAs. In spiking experiments, a low concentration of exogenous IFX (5 µg/ml) hampered ADA detection with Theradiag in sera samples with ADA levels of between 3 and 10 µg/ml. In the Immundiagnostik assay detection interference was only observed at concentrations of exogenous IFX higher than 30 µg/ml. However, in samples with high levels of ADAs (>25 µg/ml) interference was only observed at IFX concentrations higher than 100 µg/ml in all three assays. Binary (IFX/ADA) stratification of the results showed that IFX+/ADA- and IFX-/ADAs+ were less influenced by the assay results than the double-positive (IFX+/ADAs+) and double-negative (IFX-/ADAs-) combination. Conclusions: All three methodologies are equally suitable for measuring IFX levels. However, erroneous therapeutic decisions may occur when patients show double-negative (IFX-/ADAs-) or double-positive (IFX+/ADAs+) status, since agreement between

  19. An improved Bathocuproine assay for accurate valence identification and quantification of copper bound by biomolecules.

    Science.gov (United States)

    Chen, Dinglong; Darabedian, Narek; Li, Zhiqiang; Kai, Tianhan; Jiang, Dianlu; Zhou, Feimeng

    2016-03-15

    Copper is an essential metal in all organisms. Reliably quantifying and identifying the copper content and oxidation state is crucial, since the information is essential to understanding protein structure and function. Chromophoric ligands, such as Bathocuproine (BC) and its water-soluble analog, Bathocuproinedisulfonic acid (BCS), preferentially bind Cu(I) over Cu(II), and therefore have been widely used as optical probes to determine the oxidation state of copper bound by biomolecules. However, the BCS assay is commonly misused, leading to erroneous conclusions regarding the role of copper in biological processes. By measuring the redox potential of Cu(II)-BCS2 and conducting UV-vis absorption measurements in the presence of oxidizable amino acids, the thermodynamic origin of the potential artifacts becomes evident. The BCS assay was improved by introducing a strong Cu(II) chelator EDTA prior to the addition of BCS to prevent interference that might arise from Cu(II) present in the sample. The strong Cu(II) chelator rids of all the potential errors inherent in the conventional BCS assay. Applications of the improved assay to peptides and protein containing oxidizable amino acid residues confirm that free Cu(II) no longer leads to artifacts, thereby resolving issues related to this persistently misused colorimetric assay of Cu(I) in biological systems.

  20. Thrombotic risk assessment in antiphospholipid syndrome: the role of new antibody specificities and thrombin generation assay.

    Science.gov (United States)

    Sciascia, Savino; Baldovino, Simone; Schreiber, Karen; Solfietti, Laura; Radin, Massimo; Cuadrado, Maria J; Menegatti, Elisa; Erkan, Doruk; Roccatello, Dario

    2016-01-01

    Antiphospholipid syndrome (APS) is an autoimmune condition characterized by the presence of antiphospholipid antibodies (aPL) in subjects presenting with thrombosis and/or pregnancy loss. The currently used classification criteria were updated in the international consensus held in Sidney in 2005. Vascular events seem to result of local procoagulative alterations upon triggers influence (the so called "second-hit theory"), while placental thrombosis and complement activation seem to lead to pregnancy morbidity. The laboratory tests suggested by the current classification criteria include lupus anticoagulant, a functional coagulation assay, and anticardiolipin and anti-β2-glycoprotein-I antibodies, generally detected by solid phase enzyme-linked immunosorbent assay. The real challenge for treating physicians is understanding what is the actual weight of aPL in provoking clinical manifestations in each case. As thrombosis has a multi-factorial cause, each patient needs a risk-stratified approach. In this review we discuss the role of thrombotic risk assessment in primary and secondary prevention of venous and arterial thromboembolic disease in patients with APS, focusing on new antibody specificities, available risk scoring models and new coagulation assays.

  1. High yield purification of Plasmodium falciparum merozoites for use in opsonizing antibody assays.

    Science.gov (United States)

    Hill, Danika L; Eriksson, Emily M; Schofield, Louis

    2014-07-17

    Plasmodium falciparum merozoite antigens are under development as potential malaria vaccines. One aspect of immunity against malaria is the removal of free merozoites from the blood by phagocytic cells. However assessing the functional efficacy of merozoite specific opsonizing antibodies is challenging due to the short half-life of merozoites and the variability of primary phagocytic cells. Described in detail herein is a method for generating viable merozoites using the E64 protease inhibitor, and an assay of merozoite opsonin-dependent phagocytosis using the pro-monocytic cell line THP-1. E64 prevents schizont rupture while allowing the development of merozoites which are released by filtration of treated schizonts.  Ethidium bromide labelled merozoites are opsonized with human plasma samples and added to THP-1 cells. Phagocytosis is assessed by a standardized high throughput protocol. Viable merozoites are a valuable resource for assessing numerous aspects of P. falciparum biology, including assessment of immune function. Antibody levels measured by this assay are associated with clinical immunity to malaria in naturally exposed individuals. The assay may also be of use for assessing vaccine induced antibodies.  

  2. Measurement of antibodies to pneumococcal, meningococcal and haemophilus polysaccharides, and tetanus and diphtheria toxoids using a 19-plexed assay.

    Science.gov (United States)

    Whitelegg, Alison M E; Birtwistle, Jane; Richter, Alex; Campbell, John P; Turner, James E; Ahmed, Tarana M; Giles, Lynda J; Fellows, Mark; Plant, Tim; Ferraro, Alastair J; Cobbold, Mark; Drayson, Mark T; MacLennan, Calman A

    2012-03-30

    The measurement of antibody responses to vaccination is useful in the assessment of immune status in suspected immune deficiency. Previous reliance on enzyme-linked immunoabsorbent assays (ELISA) has been cumbersome, time-consuming and expensive. The availability of flow cytometry systems has led to the development of multiplexed assays enabling simultaneous measurement of antibodies to several antigens. We optimized a flow cytometric bead-based assay to measure IgG and IgM concentrations in serum to 19 antigens contained in groups of bacterial subunit vaccines: pneumococcal vaccines, meningococcal vaccines, Haemophilus influenzae b (Hib), and tetanus and diphtheria toxoid vaccines. 89-SF was employed as the standard serum. The assay was used to determine specific antibody levels in serum from 193 healthy adult donors. IgG and pneumococcal IgM antibody concentrations were measurable across 3 log10 ranges encompassing the threshold protective IgG antibody levels for each antigen. There was little interference between antibody measurements by the 19-plexed assay compared with monoplexed assays, and a lack of cross-reactive IgG antibody, but evidence for cross-reacting IgM antibody for 3/19 pneumococcal antigens. 90th centile values for 15/19 IgG concentrations and 12/12 IgM concentrations of the 193 adult sera were within these ranges and percentages of sera containing protective IgG antibody levels varied from 4% to 95% depending on antigen. This multiplexed assay can simultaneously measure antibody levels to 19 bacterial vaccine antigens. It is suitable for use in standard clinical practice to assess the in vivo immune response to test vaccinations and measure absolute antibody levels to these antigens.

  3. Comparison of antibody responses to human papillomavirus vaccination as measured by three assays

    Directory of Open Access Journals (Sweden)

    Hilary Ann Robbins

    2014-01-01

    Full Text Available Background: Different assays, including the competitive Luminex immunoassay (cLIA, secreted alkaline phosphatase neutralization assay (SEAP-NA, and virus-like particle-based ELISA, are commonly used to measure antibody responses after human papillomavirus (HPV vaccination. Direct assay comparisons aid interpretation of immunogenicity data evaluated by different assays. Methods: We compared cLIA to SEAP-NA and ELISA among 51 HPV16/18-vaccinated women enrolled in the Costa Rica Vaccine Trial. We tested replicate serum samples collected at months 0, 1, and 12 by HPV16/18 cLIA, SEAP-NA, and ELISA. For a subset (N=10, we further tested month 24 and 36 samples. We calculated seroprevalence estimates and Spearman rank correlation coefficients comparing cLIA to SEAP-NA and ELISA.Results: After one vaccine dose, seroprevalence by SEAP-NA and ELISA was 100% (both HPV16 and HPV18, and by cLIA was 96% (95% CI 87%-100% for HPV16 and 71% (95% CI 56%-83% for HPV18. Seroprevalence was 100% by all assays after 3 doses. Correlation between assays was high after one vaccine dose (cLIA/SEAP-NA ρ=0.91 (HPV16 and ρ=0.86 (HPV18; cLIA/ELISA ρ=0.84 (HPV16 and ρ=0.74 (HPV18; all p<0.001 and remained high through month 36. Ratios of mean antibody levels to seropositivity cutoffs at month 36 were lower for cLIA than for SEAP-NA or ELISA, particularly for HPV18 (HPV18 ratio for cLIA 1.9, SEAP-NA 3.5, ELISA 3.4.Conclusion: Though correlation between cLIA and SEAP-NA/ELISA is high and stable after vaccination, the assays differ in scale and sensitivity, with notable differences after 1 vaccine dose and for HPV18. Our results demonstrate that comparisons of antibody responses to HPV vaccination measured by different assays are approximate, and must consider biological and technical differences between assays.

  4. Comparison of two enzyme-linked immunosorbent assays and one rapid immunoblot assay for detection of herpes simplex virus type 2-specific antibodies in serum

    NARCIS (Netherlands)

    Groen, J; Van Dijk, G; Niesters, H G; Van Der Meijden, W I; Osterhaus, A D

    The sensitivities and specificities of three immunoassays for the detection of herpes simplex virus type 2 (HSV-2)-specific immunoglobulin G antibodies in serum, including the one-strip rapid immunoblot assay (RIBA; Chiron Corporation) and two indirect enzyme immunosorbent assays (EIA; Gull

  5. Sensitive detection of p53 antibodies in a homogeneous fluorescence assay format

    Science.gov (United States)

    Neuweiler, Hannes; Schulz, Andreas; Wolfrum, Juergen M.; Sauer, Markus

    2002-06-01

    Circulating p53 autoantibodies are found to be a universal and highly specific tumor marker for malignant diseases. Hence, sereological screening for p53 autoantibodies at low concentration levels has become increasingly relevant for early-stage and follow-up of tumor diagnostics. We developed a new method for the highly sensitive detection of p53 antibodies in a homogeneous fluorescence assay format. Short, linear peptide derived form antibody recognition sequences so human p53 were labeled with an oxazine dye. Hydrophobic interactions constrain a conformation, where the dye interacts selectively with a tryptophan residue in the peptide sequence. Subsequently, the fluorescence of the dye is quenched efficiently due to electron transfer from the indole derivative to the dye in the excited state. Specific antibody recognition induces a conformational change in the peptide structure, repealing the dye-tryptophan interaction. Consequently, a fluorescence increase upon antibody binding signals the binding event. The long-wavelength absorption and emission characteristics of the probe and the use of a red pulsed diode laser as excitation source in a confocal fluorescence microscopic set-up allows ultra sensitive antibody detection at the single-molecule level. The effectiveness of the probes are highlighted by the detection of individual p53 autoantibodies directly in serum dilutions of cancer patients.

  6. Assessment of assay sensitivity and precision in a malaria antibody ELISA.

    Science.gov (United States)

    Rajasekariah, G Halli R; Kay, Graeme E; Russell, Natrice V; Smithyman, Anthony M

    2003-01-01

    Many types of ELISA-based immunodiagnostic test kits are commercially available in the market for specific indications. These kits provide necessary assay components, reagents, and guidelines to perform the assay under designated optimal conditions. By using these kits, any unknown or test sample can be assessed as negative or positive based on the results of referral calibrator (Ref+ve and Ref-ve) samples. It is essential to provide reliable test kits to end-users with adequate quality control analysis. Therefore, it is necessary to check the kit for any variations in its performance. While developing a malaria antibody ELISA test-kit, we optimized assay conditions with chequer-board analyses and developed an assay protocol. We have taken out kits randomly from the assembly line and had them evaluated by operators who are new to the test-kits. Assays are performed as per the test guidelines provided. Sera, diluted serially, have shown a clear discriminatory signal between a negative vs. positive sample. A COV is determined by evaluating the Ref-ve calibrator in replicate antigen-coated wells from 6 different plates. This COV is used as a tool to determine S/N ratio of test samples. Besides Ref-ve and Ref+ve calibrators, additional field serum samples are tested with the test kit. Several performance indices, such as mean, standard deviation, %CV are calculated, and the inter- and intra-assay variations determined. The assay precision is determined with large and small replicate samples. In addition, assays are performed concurrently in triplicate-, duplicate-, and single-wells, and the results are analyzed for any assay variations. Different plate areas are identified in antigen-coated 96-well plates and tested blind to detect any variations. The S/N ratio is found to be a very effective tool in determining the assay sensitivity. The %CV was within 10-15%. Variations seen in the assays are found to be due to operator errors and not due to kit reagents. These

  7. Performance of commercial enzyme-linked immunosorbent assays for detection of antibodies to Bordetella pertussis.

    Science.gov (United States)

    Riffelmann, M; Thiel, K; Schmetz, J; Wirsing von Koenig, C H

    2010-12-01

    Measuring antibodies to Bordetella pertussis antigens is mostly done by enzyme-linked immunosorbent assays (ELISAs). We compared the performance of ELISA kits that were commercially available in Germany. Eleven measured IgG antibodies, and nine measured IgA antibodies. An in-house ELISA with purified antigens served as a reference method. Samples included two WHO reference preparations, the former Food and Drug Administration (FDA)/Center for Biologics Evaluation and Research (CBER) reference preparations, serum samples from patients with clinically suspected pertussis, and serum samples from patients having received a combined tetanus, diphtheria, and pertussis (Tdap) vaccination. Kits using pertussis toxin (PT) as an antigen showed linearity compared to the WHO Reference preparation (r2 between 0.82 and 0.99), and these kits could quantify antibodies according to the reference preparation. ELISA kits using mixed antigens showed no linear correlation to the reference preparations. Patient results were compared to results of in-house ELISAs using a dual cutoff of either ≥100 IU/ml anti-PT IgG or ≥40 IU/ml anti-PT IgG together with ≥12 IU/ml anti-PT IgA. The sensitivities of kits measuring IgG antibodies ranged between 0.84 and 1.00. The specificities of kits using PT as an antigen were between 0.81 and 0.93. The specificities of kits using mixed antigens were between 0.51 and 0.59 and were thus not acceptable. The sensitivities of kits measuring IgA antibodies ranged between 0.53 and 0.73, and the specificities were between 0.67 and 0.94, indicating that IgA antibodies may be of limited diagnostic value. Our data suggest that ELISAs should use purified PT as an antigen and be standardized to the 1st International Reference preparation.

  8. Motility assays using myosin attached to surfaces through specific binding to monoclonal antibodies.

    Science.gov (United States)

    Winkelmann, D A; Bourdieu, L; Kinose, F; Libchaber, A

    1995-04-01

    We have analyzed the dependence of actin filament movement on the mode of myosin attachment to surfaces. Monoclonal antibodies that bind to three distinct sites were used to tether myosin to nitrocellulose-coated glass. One antibody reacts with an epitope on the regulatory light chain located at the head-rod junction. The other two react with sites in the rod domain, one in the S2 region near the S2-LMM hinge, and the other at the C terminus of the myosin rod. These monoclonal antibodies were used to provide increasing flexibility in the mode of attachment. Fast skeletal muscle myosin monomers were bound to the surfaces through the specific interaction with these monoclonal antibodies and the sliding movement of fluorescently labeled actin filaments analyzed by video microscopy. Each of these antibodies produced stable, myosin-coated surfaces that supported uniform movement of actin over the course of several hours. Attachment of myosin through the anti-S2 and anti-LMM monoclonal antibodies yielded a maximum velocity of 10 microns/s at 30 degrees C, whereas attachment through anti-LC2 produced a lower velocity of 4-5 microns/s. Each antibody showed a characteristic minimum myosin density below which sliding movement was no longer supported and an exponential dependence of actin filament velocity on myosin surface density below Vmax. Maximum sliding velocity was achieved over a range of myosin surface densities. Thus, the specific mode of attachment can influence the characteristic velocity of actin filament movement and the surface density needed to support movement. These data are being used to analyze the dynamics of sliding filament assays and evaluate estimates of the average number of motor molecules per unit length of actin required to support movement.

  9. Detection of antibodies to Actinobacillus pleuropneumoniae serotype 12 in pig serum using a blocking enzyme-linked immunosorbent assay

    DEFF Research Database (Denmark)

    Andresen, Lars Ole; Klausen, Joan; Barfod, Kristen

    2002-01-01

    in samples of pig serum were detected by inhibition of the binding of polyclonal rabbit antibodies raised against Ap serotype 12. The assay was evaluated against sera from experimentally infected pigs, from pig herds naturally infected with Ap and from herds declared free of Ap serotypc 12 infection......The objective was to develop a blocking enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to Actinobacillus pleuropneumoniae (Ap) serotype 12 in pig serum. Lipopolysaccharide (LPS) from Ap serotype 12 was purified and used as antigen in the assay. Antibodies to the LPS antigen...

  10. Development of an in Vitro Potency Assay for Anti-anthrax Lethal Toxin Neutralizing Antibodies

    Directory of Open Access Journals (Sweden)

    Sjoerd Rijpkema

    2012-01-01

    Full Text Available Lethal toxin (LT of Bacillus anthracis reduces the production of a number of inflammatory mediators, including transcription factors, chemokines and cytokines in various human cell lines, leading to down-regulation of the host inflammatory response. Previously we showed that the reduction of interleukin-8 (IL-8 is a sensitive marker of LT-mediated intoxication in human neutrophil-like NB-4 cells and that IL-8 levels are restored to normality when therapeutic monoclonal antibodies (mAb with toxin-neutralising (TN activity are added. We used this information to develop cell-based assays that examine the effects of TN therapeutic mAbs designed to treat LT intoxication and here we extend these findings. We present an in vitro assay based on human endothelial cell line HUVEC jr2, which measures the TN activity of therapeutic anti-LT mAbs using IL-8 as a marker for intoxication. HUVEC jr2 cells have the advantage over NB-4 cells that they are adherent, do not require a differentiation step and can be used in a microtitre plate format and therefore can facilitate high throughput analysis. This human cell-based assay provides a valid alternative to the mouse macrophage assay as it is a more biologically relevant model of the effects of toxin-neutralising antibodies in human infection.

  11. Reporter gene assay for the quantification of the activity and neutralizing antibody response to TNFα antagonists

    DEFF Research Database (Denmark)

    Lallemand, Christophe; Kavrochorianou, Nadia; Steenholdt, Casper;

    2011-01-01

    relative to Renilla luciferase expression. Thus, results are independent of cell number or differences in cell viability, resulting in intra and inter assay coefficients of variation of 10% or less. Normalization of results relative to the expression of an internal standard also provides a means......A cell-based assay has been developed for the quantification of the activity of TNFa antagonists based on human erythroleukemic K562 cells transfected with a NF¿B regulated firefly luciferase reporter-gene construct. Both drug activity and anti-drug neutralizing antibodies can be quantified...... with a high degree of precision within 2h, and without interference from cytokines and other factors known to activate NF¿B. The assay cells also contain the Renilla luciferase reporter gene under the control of a constitutive promoter that allows TNFa-induced firefly luciferase activity to be normalized...

  12. Reporter gene assay for the quantification of the activity and neutralizing antibody response to TNFα antagonists

    DEFF Research Database (Denmark)

    Lallemand, Christophe; Kavrochorianou, Nadia; Steenholdt, Casper;

    2011-01-01

    relative to Renilla luciferase expression. Thus, results are independent of cell number or differences in cell viability, resulting in intra and inter assay coefficients of variation of 10% or less. Normalization of results relative to the expression of an internal standard also provides a means......A cell-based assay has been developed for the quantification of the activity of TNFα antagonists based on human erythroleukemic K562 cells transfected with a NFκB regulated firefly luciferase reporter-gene construct. Both drug activity and anti-drug neutralizing antibodies can be quantified...... with a high degree of precision within 2h, and without interference from cytokines and other factors known to activate NFκB. The assay cells also contain the Renilla luciferase reporter gene under the control of a constitutive promoter that allows TNFα-induced firefly luciferase activity to be normalized...

  13. An improved haemolytic plaque assay for the detection of cells secreting antibody to bacterial antigens

    DEFF Research Database (Denmark)

    Barington, T; Heilmann, C

    1992-01-01

    SC with specificity for tetanus and diphtheria toxoid as well as for Haemophilus influenzae type b and pneumococcal capsular polysaccharides. These assays were found to be less time consuming, more economical and yielded 1.9-3.4-fold higher plaque numbers than traditional Jerne-type PFC assays. In the case of anti......-polysaccharide AbSC of the IgG isotype, the increase was as high as 7.4-11.8 times. Evidence is presented that the pronounced improvement in the detection of the latter is due to the presence of aggregating anti-IgG antibody from the beginning of the assay. It is proposed that in the case of low affinity of anti...

  14. Comparison of a Multiplex Flow Cytometric Assay with Enzyme-Linked Immunosorbent Assay for Quantitation of Antibodies to Tetanus, Diphtheria, and Haemophilus influenzae Type b

    OpenAIRE

    Pickering, Jerry W.; Martins, Thomas B.; Schroder, M. Carl; Hill, Harry R.

    2002-01-01

    We developed a multiplexed indirect immunofluorescence assay for antibodies to Haemophilus influenza type b (Hib) polysaccharide and the toxoids of Clostridium tetani (Tet) and Corynebacterium diphtheriae (Dip) based on the Luminex multiple-analyte profiling system. A pooled serum standard was calibrated against World Health Organization standards for Dip and Tet and an international standard for Hib. The multiplexed Luminex assay was compared to individual enzyme-linked immunosorbent assays ...

  15. An extended set of yeast-based functional assays accurately identifies human disease mutations

    Science.gov (United States)

    Sun, Song; Yang, Fan; Tan, Guihong; Costanzo, Michael; Oughtred, Rose; Hirschman, Jodi; Theesfeld, Chandra L.; Bansal, Pritpal; Sahni, Nidhi; Yi, Song; Yu, Analyn; Tyagi, Tanya; Tie, Cathy; Hill, David E.; Vidal, Marc; Andrews, Brenda J.; Boone, Charles; Dolinski, Kara; Roth, Frederick P.

    2016-01-01

    We can now routinely identify coding variants within individual human genomes. A pressing challenge is to determine which variants disrupt the function of disease-associated genes. Both experimental and computational methods exist to predict pathogenicity of human genetic variation. However, a systematic performance comparison between them has been lacking. Therefore, we developed and exploited a panel of 26 yeast-based functional complementation assays to measure the impact of 179 variants (101 disease- and 78 non-disease-associated variants) from 22 human disease genes. Using the resulting reference standard, we show that experimental functional assays in a 1-billion-year diverged model organism can identify pathogenic alleles with significantly higher precision and specificity than current computational methods. PMID:26975778

  16. An improved method for utilization of peptide substrates for antibody characterization and enzymatic assays.

    Science.gov (United States)

    Ghosh, Inca; Sun, Luo; Evans, Thomas C; Xu, Ming-Qun

    2004-10-01

    Synthetic peptides have become an important tool in antibody production and enzyme characterization. The small size of peptides, however, has hindered their use in assays systems, such as Western blots, and as immunogens. Here, we present a facile method to improve the properties of peptides for multiple applications by ligating the peptides to intein-generated carrier proteins. The stoichiometric ligation of peptide and carrier achieved by intein-mediated protein ligation (IPL) results in the ligation product migrating as a single band on a SDS-PAGE gel. The carrier proteins, HhaI methylase (M.HhaI) and maltose-binding protein (MBP), were ligated to various peptides; the ligated carrier-peptide products gave sharp, reproducible bands when used as positive controls for antibodies raised against the same peptides during Western blot analysis. We further show that ligation of the peptide antigens to a different thioester-tagged carrier protein, paramyosin, produced immunogens for the production of antisera in rabbits or mice. Furthermore, we demonstrate the generation of a substrate for enzymatic assays by ligating a peptide containing the phosphorylation site for Abl protein tyrosine kinase to a carrier protein. This carrier-peptide protein was used as a kinase substrate that could easily be tested for phosphorylation using a phosphotyrosine antibody in Western blot analysis. These techniques do not require sophisticated equipment, reagents, or skills thereby providing a simple method for research and development.

  17. Rapid enzyme-linked immunosorbent assay for the detection of hantavirus-specific antibodies in divergent small mammals.

    Science.gov (United States)

    Cautivo, Karla; Schountz, Tony; Acuña-Retamar, Mariana; Ferrés, Marcela; Torres-Pérez, Fernando

    2014-05-06

    We assessed the utility of an enzyme-linked immunosorbent assay (ELISA) for the detection of hantavirus-specific antibodies from sera of Oligoryzomys longicaudatus, the principal reservoir of Andes virus (ANDV), using an antigen previously developed for detection of antibodies to Sin Nombre virus (SNV) in sera from Peromyscus maniculatus. The assay uses a protein A/G horseradish peroxidase conjugate and can be performed in as little as 1.5 hours. Serum samples from Oligoryzomys longicaudatus collected in central-south Chile were used and the assay identified several that were antibody positive. This assay can be used for the rapid detection of antibodies to divergent hantaviruses from geographically and phylogenetically distant rodent species.

  18. Comparative assay of fluorescent antibody test results among twelve European National Reference Laboratories using various anti-rabies conjugates

    DEFF Research Database (Denmark)

    Robardet, E.; Andrieu, S.; Rasmussen, Thomas Bruun

    2013-01-01

    Twelve National Reference Laboratories (NRLs) for rabies have undertaken a comparative assay to assess the comparison of fluorescent antibody test (FAT) results using five coded commercial anti-rabies conjugates (Biorad, Bioveta, Fujirebio, Millipore, and SIFIN conjugates). Homogenized positive...

  19. Rapid Enzyme-Linked Immunosorbent Assay for the Detection of Hantavirus-Specific Antibodies in Divergent Small Mammals

    Directory of Open Access Journals (Sweden)

    Karla Cautivo

    2014-05-01

    Full Text Available We assessed the utility of an enzyme-linked immunosorbent assay (ELISA for the detection of hantavirus-specific antibodies from sera of Oligoryzomys longicaudatus, the principal reservoir of Andes virus (ANDV, using an antigen previously developed for detection of antibodies to Sin Nombre virus (SNV in sera from Peromyscus maniculatus. The assay uses a protein A/G horseradish peroxidase conjugate and can be performed in as little as 1.5 hours. Serum samples from Oligoryzomys longicaudatus collected in central-south Chile were used and the assay identified several that were antibody positive. This assay can be used for the rapid detection of antibodies to divergent hantaviruses from geographically and phylogenetically distant rodent species.

  20. Antibodies with specificity for native and denatured forms of ovalbumin differ in reactivity between enzyme-linked immunosorbent assays

    DEFF Research Database (Denmark)

    Holm, B. E.; Bergmann, Ann Christina; Hansen, Paul Robert

    2015-01-01

    In this study, polyclonal and monoclonal antibodies to native and denatured chicken ovalbumin (OVA) were produced to compare their dependency on continuous and three-dimensional epitopes. These antibodies were characterized with respect to reactivity to native and denatured OVA by enzyme......-linked immunosorbent assay (ELISA) employing surface-bound OVA and streptavidin-capture ELISA to determine whether effects of different coating influence antibody specificity and with respect to epitope specificity by peptide ELISA, using overlapping peptides, covering the complete OVA sequence. Polyclonal antibodies...... to native OVA reacted strongly with native and denatured OVA in both assays, but did not react with the overlapping peptides. Polyclonal antibodies to denatured OVA reacted strongly with both OVA forms and with several of the overlapping peptides. Monoclonal antibodies to native OVA reacted preferentially...

  1. Adapting dried blood spot sampling for an anti-therapeutic antibody immunogenicity assay.

    Science.gov (United States)

    Xiang, Yuhong; Welch, Mackenzie; Amaravadi, Lakshmi; Stebbins, Christopher

    2013-07-31

    Dried blood spot sampling is a microvolume sampling technique with many potential advantages. It allows for easier handling and less expensive shipment and storage of biological samples. Additionally, it can provide ethical benefits in the pre-clinical setting through a reduction in animal usage by allowing intensive serial sample collection from the same animals. In the clinical setting, ease of sample collection, greater flexibility of sample storage, and shipping are distinct advantages. These advantages can enhance preclinical and clinical data quality, where immunogenicity monitoring plays an important role in the interpretation of pharmacokinetic data. To date, a method for usage of dried blood spot sampling with an immunogenicity assay has not been published. Herein we demonstrate that the measurement of anti-drug antibodies (ADA) using DBS was comparable to traditional methods in terms of reproducibility, assay sensitivity and drug tolerance. The data demonstrate that DBS is a viable sample collection method, and in some cases may be preferred, over classic serum or plasma sampling for antidrug antibody assays. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Development of an enzyme-linked immunosorbent assay for the monitoring and surveillance of antibodies to porcine epidemic diarrhea virus based on a recombinant membrane protein.

    Science.gov (United States)

    Fan, Jing-Hui; Zuo, Yu-Zhu; Shen, Xiao-Qiang; Gu, Wen-Yuan; Di, Jing-Mei

    2015-12-01

    The recent dramatic increase in reported cases of porcine epidemic diarrhea (PED) in pig farms is a potential threat to the global swine industry. Therefore, the accurate diagnosis, serological monitoring, and surveillance of specific antibodies in pigs resulting from porcine epidemic diarrhea virus (PEDV) infection or vaccination would be essential in helping to control the spread of PED. We developed and validated an indirect enzyme-linked immunosorbent assay (ELISA) based on the recombinant membrane (M) protein of PEDV. To detect PEDV antibodies in eight herds, 382 serum samples were collected from sows that had been immunized with a PED vaccine, and screened using the developed ELISA in parallel with a serum neutralization (SN) assay. Of the tested samples, 276 were positive for the presence of PEDV antibodies according to both assays, while 98 were negative. An excellent agreement between the ELISA and the SN assay was observed (kappa=0.947; 95% confidence interval=0.910-0.984; McNemar's test, P=0.727). No cross-reaction was detected for the developed ELISA with other coronaviruses or other common pig pathogens. The developed ELISA could be used for serological evaluation and indirect diagnosis of PED infection.

  3. Development of 316v antibody enzyme-linked immunosorbent assay for detection of paratuberculosis in sheep.

    Science.gov (United States)

    Gurung, R B; Begg, D J; Purdie, A C; Eamens, G J; Whittington, R J

    2015-12-01

    An enzyme-linked immunosorbent assay (ELISA) was developed and optimised using a Mycobacterium avium subspecies paratuberculosis (MAP) antigen prepared from a C strain (316v) passed through a French press. The optimised assay was evaluated with a panel of sera from MAP infected (n = 66) and uninfected (n = 1,092) sheep. Animals in the MAP infected category were positive on either tissue culture or histopathology but were of unknown serum antibody status. The diagnostic performance and cost of the assay were compared with those of a commercial ELISA (IDEXX). At 99.8% diagnostic specificity the assay showed a diagnostic sensitivity of 23% (95% CI: 15.1-35.8) compared with 36.4% (95% CI: 25.8-48.4) for the commercial ELISA (McNemar's test: chi-square 5.82, p ELISA for an equivalent number of tests, the multiple depending on the number of plates processed per run. For flock-level surveillance, to account for the lower sensitivity of the 316v ELISA compared with the commercial ELISA, sample sizes would be increased but the test cost would still be lower. The 316v assay will be useful for diagnosis of Johne's disease in sheep flocks, particularly in developing countries where labour costs are low relative to the cost of consumables.

  4. Detection of TGEV Antibody by Enzyme-Linked Immunosorbent Assay Using Recombinant Nucleocapsid Proteins

    Institute of Scientific and Technical Information of China (English)

    YU Li-yun; HOU Xi-lin

    2005-01-01

    An enzyme linked immunosorbent assays (ELISA) based on recombinant nucleocapsid (N) protein generated in Escherichia coli was evaluated for its sensitivity and specificity for diagnosis of transmissible gastroenteritis virus (TGEV) infection.The N gene encoding the N protein was cloned and expressed as a fusion protein with His tag protein in E. coli. The recombinant N protein migrated at 42 kDa and reacted with His6 tag specific monoclonal antibody by immunoblotting.Recombinant N protein ELISA (rnELISA) demonstrated 97.5% specificity among 80 TGEV-free individuals, and 97.3%sensitivity ranging among 110 clinical samples with TGEV. Taken together, these results indicated that nucleocapsid may be a useful antigen for the sera-diagnosis of TGEV and it was also suggested that the ELISA is a highly sensitive and specific test for detecting antibodies against TGEV.

  5. Diagnostic accuracy and comparison of two assays for Borrelia-specific IgG and IgM antibodies

    DEFF Research Database (Denmark)

    Dessau, Ram

    2013-01-01

    Two assays (Liaison, Diasorin; IDEIA, Oxoid) for detection of Borrelia-specific antibodies were compared. A case-control design using patients with neuroborreliosis (n = 48), laboratory defined by a positive Borrelia-specific antibody index in the spinal fluid, was available and was intended...

  6. Blocking enzyme-linked immunosorbent assay for detection of antibodies against Actinobacillus pleuropneumoniae serotype 6 in pig serum

    DEFF Research Database (Denmark)

    Klausen, Joan; Andresen, Lars Ole; Barfod, Kristen

    2001-01-01

    A blocking enzyme-linked immunosorbent assay (ELISA) detecting antibodies against Actinobacillus pleuropneumoniae (Ap) serotype 6 was developed. The blocking ELISA was based on the inhibition of a polyclonal antibody raised against Ap serotype 6. Purified lipopolysaccharide from Ap serotype 6...

  7. Development of a high-throughput opsonophagocytic assay for the determination of functional antibody activity against Streptococcus pyogenes using bioluminescence.

    Science.gov (United States)

    Lorenz, Natalie; Loh, Jacelyn M S; Moreland, Nicole J; Proft, Thomas

    2017-03-01

    The lack of standardised protocols for the assessment of functional antibodies has hindered Streptococcus pyogenes research and the development of vaccines. A robust, high throughput opsonophagocytic bactericidal assay to determine protective antibodies in human and rabbit serum has been developed that utilises bioluminescence as a rapid read out.

  8. Validation of a KHV antibody enzyme-linked immunosorbent assay (ELISA)

    DEFF Research Database (Denmark)

    Bergmann, S M; Wang, Q; Zeng, W

    2017-01-01

    Koi herpesvirus (KHV) causes KHV disease (KHVD). The virus is highly contagious in carp or koi and can induce a high mortality. Latency and, in some cases, a lack of signs presents a challenge for virus detection. Appropriate immunological detection methods for anti-KHV antibodies have not yet been...... and was particularly useful at the pond or farm levels. Considering the scale of the carp and koi industry worldwide, this assay represents an important practical tool for the indirect detection of KHV, also in the absence of clinical signs....

  9. Peroxidase-linked assay for detection of antibodies against bovine leukosis virus.

    Science.gov (United States)

    de Castro, Clarissa C; Nunes, Cristina F; Finger, Paula F; Siedler, Bianca S; Dummer, Luana; de Lima, Marcelo; Leite, Fábio P L; Fischer, Geferson; Vargas, Gilberto D'A; Hübner, Silvia de O

    2013-01-01

    A peroxidase linked assay (PLA) was designed to screen bovine sera for the presence of specific antibodies against bovine leukosis virus (BLV). Out of 201 samples of bovine sera analyzed, 52.2% were considered positive by PLA, 26.4% by AGID, and 38.9% by ELISA. Western blotting analyses excluded 27 samples found to be positive by PLA. PLA showed 100% of sensitivity when compared with AGID and ELISA. Specificity was 64.8% and 78%, respectively (kappa coefficients were 0.70 and 0.83). These findings indicate that PLA can be used as an alternative method for the diagnosis of BLV infection in cattle.

  10. Enzyme-linked immunosorbent Assay for detecting of antibody to canine distemper virus

    Directory of Open Access Journals (Sweden)

    Sudarisman

    2006-03-01

    Full Text Available Serum neutralisation test (SNT has been established for evaluating canine distemper vaccination, but until now SNT was rarely used due to the need for continuous tissue culture facilities and requires 3 days to perform. For detecting antibody to canine distemper virus, an enzyme-linked immunosorbent assay (ELISA is relatively simple and rapid seroassay. ELISA for canine immunoglobulin (Ig G antibodies to canine distemper virus (CDV was developed by using Onderstepoort strain of canine distemper virus as coating antigen. Rabbit anti canine IgG labelled with horse radish peroxidase was used as the conjugate, while phenylenediamine dihydrochloride (OPD was used as the substrate. The ELISA results were then compared with the results of the SNT, using the sera of 312 random-source dogs from West Java. The two test-results had a high degree of correlation. Very few discrepancies occurred and most of these were at the lower limits of each test. When the sera were tested at 1 : 100 dilutions, there was a 95.5% agreement between the ELISA and SNT. Their sensitivity and spesificity were 83.9 and 98.4%. Titrated SNT and ELISA also were performed on sera from 7 dogs whose lifetime medical histories were known. The antibodies were inclining up after two months of post vaccination, where the titre was not in zero/lower position at the day of vaccination. However, antibody zero or low position were found at 28 days post vaccination. All of the results indicated that ELISA can be used for evaluating antibody to canine distemper virus response, replacing the SNT.

  11. Application of serum NY-ESO-1 antibody assay for early SCLC diagnosis.

    Science.gov (United States)

    Yang, Jihua; Jiao, Shunchang; Kang, Jingbo; Li, Rong; Zhang, Guanzhong

    2015-01-01

    NY-ESO-1 antibody is one of the cancer-related antibodies. The purpose of this study was to investigate the diagnostic role of the NY-ESO-1 humoral immune response in small cell lung cancer (SCLC). We recombined the recombinant protein of NY-ESO-1 antibody and NSE, analyzed them by Enzyme-linked immunosorbent assay, and then established the Receiver Operating Characteristic (ROC) curve to estimate the diagnostic value of NY-ESO-1 antibody, NSE and their combinations. According to detection, the positive rate of NY-ESO-1 humoral immune response (26.3%), NSE (43.8%) and their combinations (10.5%) were all lower than the negative rate which indicated that the NY-ESO-1 antibody might be down-regulated in SCLC. And the positive rate wasn't related to clinicopathologic characteristics. The ROC curve demonstrated that with a 37.17% sensitivity and a 91.7% specificity along with a AUC of 0.619 for NY-ESO-1ab as well as with a 48.3% sensitivity and a 90.87% specificity along with a AUC value of 0.773 for NSE, their diagnostic value were both high. Besides, the diagnostic value of their combinations was also good for a AUC of 0.83 and a 69.12% sensitivity and a 91.8% specificity. There were significant difference of diagnostic value among three types above (NY-ESO-1 vs. NSE, P ESO-1, P ESO-1ab, NSE and their combinations all were important diagnostic markers for SCLC. Moreover, the diagnostic value of their combinations was higher than any single of them. And NY-ESO-1 humoral immune to NSE might be a potential diagnostic indicator in SCLC.

  12. Preparation of monoclonal antibody of anti-feline calicivirus and establishment of double-antibody sandwich enzyme-linked immunosorbent assay detecting method.

    Science.gov (United States)

    Yuan, B; Ai, C-X; Yuan, L; Gao, W; Hu, J-P; Chen, J; Ren, W-Z

    2014-09-12

    This study aimed to prepare monoclonal antibody of feline calicivirus (FCV) and identify its basic biological characteristics. Saturated ammonium sulfate precipitation, combined differential centrifugation, and cesium chloride density gradient centrifugation were used for the purification of FCV. The purified FCV was used as antigen to immunize BALB/c mice. The hybridoma lines of anti-FCV monoclonal antibodies were established using cell fusion and hybridoma screening techniques. The subtypes of the monoclonal antibody were identified. The results showed that 3 strains of hybridoma cell lines stably secreted anti-FCV monoclonal antibody; they were named as D8, E5, and H4. The D8 and E5 were IgM subtype antibodies, and H4 was IgG2b subtype antibody. The monoclonal antibody obtained shared no cross-reactivity with feline parvovirus, canine parvovirus, and canine distemper virus. According to the different recognition sites of 2 monoclonal antibodies E5 and H4 to the FCV, they were used to coat microtiter plates and prepare 2 enzyme-labeled secondary antibodies to establish double-antibody sandwich enzyme-linked immunosorbent assay detecting method.

  13. Comparison of a multiplex flow cytometric assay with enzyme-linked immunosorbent assay for auantitation of antibodies to tetanus, diphtheria, and Haemophilus influenzae Type b.

    Science.gov (United States)

    Pickering, Jerry W; Martins, Thomas B; Schroder, M Carl; Hill, Harry R

    2002-07-01

    We developed a multiplexed indirect immunofluorescence assay for antibodies to Haemophilus influenza type b (Hib) polysaccharide and the toxoids of Clostridium tetani (Tet) and Corynebacterium diphtheriae (Dip) based on the Luminex multiple-analyte profiling system. A pooled serum standard was calibrated against World Health Organization standards for Dip and Tet and an international standard for Hib. The multiplexed Luminex assay was compared to individual enzyme-linked immunosorbent assays (ELISAs) for the same analytes. By both methods, 75 (92.6%) of 81 of random serum samples had protective levels of antibody to Tet (> or = 0.1 IU/ml). For Dip, 81.5% of the samples had protective antibody levels (> or = 0.1 IU/ml) by ELISA and 80.2% had protective antibody levels by Luminex. Protective levels (> or = 1.0 microg/ml) of antibody to Hib were found in 45.0% of the samples tested by ELISA and in 39.0% of the samples tested by Luminex. The correlations (R(2)) between ELISA and Luminex of the 81 samples were 0.96, 0.96, and 0.91 for Tet, Dip, and Hib, respectively. There was also similar agreement between Luminex and ELISA for sera collected before and 1 month after Tet, Dip, and Hib vaccine administration. Both methods detected strong postvaccination responses. The Luminex method is an attractive alternative to ELISA since it reduces labor and reagent costs, as well as assay time.

  14. Accurate Detection of Adenylation Domain Functions in Nonribosomal Peptide Synthetases by an Enzyme-linked Immunosorbent Assay System Using Active Site-directed Probes for Adenylation Domains.

    Science.gov (United States)

    Ishikawa, Fumihiro; Miyamoto, Kengo; Konno, Sho; Kasai, Shota; Kakeya, Hideaki

    2015-12-18

    A significant gap exists between protein engineering and enzymes used for the biosynthesis of natural products, largely because there is a paucity of strategies that rapidly detect active-site phenotypes of the enzymes with desired activities. Herein, we describe a proof-of-concept study of an enzyme-linked immunosorbent assay (ELISA) system for the adenylation (A) domains in nonribosomal peptide synthetases (NRPSs) using a combination of active site-directed probes coupled to a 5'-O-N-(aminoacyl)sulfamoyladenosine scaffold with a biotin functionality that immobilizes probe molecules onto a streptavidin-coated solid support. The recombinant NRPSs have a C-terminal His-tag motif that is targeted by an anti-6×His mouse antibody as the primary antibody and a horseradish peroxidase-linked goat antimouse antibody as the secondary antibody. These probes can selectively capture the cognate A domains by ligand-directed targeting. In addition, the ELISA technique detected A domains in the crude cell-free homogenates from the Escherichia coli expression systems. When coupled with a chromogenic substrate, the antibody-based ELISA technique can visualize probe-protein binding interactions, which provides accurate readouts of the A-domain functions in NRPS enzymes. To assess the ELISA-based engineering of the A domains of NRPSs, we reprogramed 2,3-dihydroxybenzoic acid (DHB)-activating enzyme EntE toward salicylic acid (Sal)-activating enzymes and investigated a correlation between binding properties for probe molecules and enzyme catalysts. We generated a mutant of EntE that displayed negligible loss in the kcat/Km value with the noncognate substrate Sal and a corresponding 48-fold decrease in the kcat/Km value with the cognate substrate DHB. The resulting 26-fold switch in substrate specificity was achieved by the replacement of a Ser residue in the active site of EntE with a Cys toward the nonribosomal codes of Sal-activating enzymes. Bringing a laboratory ELISA technique

  15. Evaluation of the Determine Syphilis TP assay for the detection of antibodies against Treponema pallidum for the serodiagnosis of syphilis.

    Science.gov (United States)

    Zhuang, Y-H; Tian, Y; Chen, Y; Tang, J; Wang, J-Q; Li, P; Li, Q; Jiang, Y-Q

    2012-06-01

    Currently, infectious syphilis has been resurgent in China and has become a significant public health problem. The rapid expansion of syphilis screening programs is urgently required. In the present study, the performance of the Determine Syphilis TP assay (Determine TP assay) for the detection of antibodies against Treponema pallidum (T. pallidum) for syphilis serodiagnosis was evaluated. In total, 300 serum samples were tested for the presence of treponemal-specific antibodies using the Treponema pallidum particle agglutination (TPPA) assay, the Determine TP assay, and the InTec immunochromatography assay (InTec assay). The Determine TP assay detected 99, 11, and 5 positive results, whereas the InTec assay detected 97, 3, and 3 positive samples from group I (100 TPPA-positive sera), group II (13 TPPA 1:80 +/- sera), and group III (187 TPPA-negative sera), respectively. The sensitivity, specificity, and the rate concordant with TPPA for the Determine TP assay were 97.35, 98.91, and 97.33%, respectively. In comparison to the TPPA, the Determine TP assay is simple to perform and time-saving, making it a favorable alternative for the detection of T. pallidum-specific antibodies where other T. pallidum-specific confirmatory tests are not available. In addition, this rapid treponemal test promotes prompt treatment for syphilis by providing early laboratory diagnosis.

  16. Enzyme-Linked Immunosorbent Assays for Detection of Equine Antibodies Specific to Sarcocystis neurona Surface Antigens†

    Science.gov (United States)

    Hoane, Jessica S.; Morrow, Jennifer K.; Saville, William J.; Dubey, J. P.; Granstrom, David E.; Howe, Daniel K.

    2005-01-01

    Sarcocystis neurona is the primary causative agent of equine protozoal myeloencephalitis (EPM), a common neurologic disease of horses in the Americas. We have developed a set of enzyme-linked immunosorbent assays (ELISAs) based on the four major surface antigens of S. neurona (SnSAGs) to analyze the equine antibody response to S. neurona. The SnSAG ELISAs were optimized and standardized with a sample set of 36 equine sera that had been characterized by Western blotting against total S. neurona parasite antigen, the current gold standard for S. neurona serology. The recombinant SnSAG2 (rSnSAG2) ELISA showed the highest sensitivity and specificity at 95.5% and 92.9%, respectively. In contrast, only 68.2% sensitivity and 71.4% specificity were achieved with the rSnSAG1 ELISA, indicating that this antigen may not be a reliable serological marker for analyzing antibodies against S. neurona in horses. Importantly, the ELISA antigens did not show cross-reactivity with antisera to Sarcocystis fayeri or Neospora hughesi, two other equine parasites. The accuracy and reliability exhibited by the SnSAG ELISAs suggest that these assays will be valuable tools for examining the equine immune response against S. neurona infection, which may help in understanding the pathobiology of this accidental parasite-host interaction. Moreover, with modification and further investigation, the SnSAG ELISAs have potential for use as immunodiagnostic tests to aid in the identification of horses affected by EPM. PMID:16148170

  17. Enzyme-linked immunosorbent assays for detection of equine antibodies specific to Sarcocystis neurona surface antigens.

    Science.gov (United States)

    Hoane, Jessica S; Morrow, Jennifer K; Saville, William J; Dubey, J P; Granstrom, David E; Howe, Daniel K

    2005-09-01

    Sarcocystis neurona is the primary causative agent of equine protozoal myeloencephalitis (EPM), a common neurologic disease of horses in the Americas. We have developed a set of enzyme-linked immunosorbent assays (ELISAs) based on the four major surface antigens of S. neurona (SnSAGs) to analyze the equine antibody response to S. neurona. The SnSAG ELISAs were optimized and standardized with a sample set of 36 equine sera that had been characterized by Western blotting against total S. neurona parasite antigen, the current gold standard for S. neurona serology. The recombinant SnSAG2 (rSnSAG2) ELISA showed the highest sensitivity and specificity at 95.5% and 92.9%, respectively. In contrast, only 68.2% sensitivity and 71.4% specificity were achieved with the rSnSAG1 ELISA, indicating that this antigen may not be a reliable serological marker for analyzing antibodies against S. neurona in horses. Importantly, the ELISA antigens did not show cross-reactivity with antisera to Sarcocystis fayeri or Neospora hughesi, two other equine parasites. The accuracy and reliability exhibited by the SnSAG ELISAs suggest that these assays will be valuable tools for examining the equine immune response against S. neurona infection, which may help in understanding the pathobiology of this accidental parasite-host interaction. Moreover, with modification and further investigation, the SnSAG ELISAs have potential for use as immunodiagnostic tests to aid in the identification of horses affected by EPM.

  18. Evaluation of the LIAISON ANA screen assay for antinuclear antibody testing in autoimmune diseases.

    Science.gov (United States)

    Ghillani, P; Rouquette, A M; Desgruelles, C; Hauguel, N; Le Pendeven, C; Piette, J C; Musset, L

    2007-08-01

    Antinuclear antibodies (ANA) are widely detected by immunofluorescence on HEp-2 cells in patients with connective tissue diseases and other pathological conditions. We evaluated the first-automated chemiluminescence immunoassay for the detection of ANA (LIAISON ANA screen, DiaSorin). This study was carried out simultaneously in two laboratories by testing 327 patient samples with clinically defined connective diseases, 273 routine samples for ANA screening, and 300 blood donors. A total of 268 out of 337 IIF-positive sera were positive with LIAISON ANA screen (79.5% of agreement) and 240 out of 263 IIF-negative sera were negative with LIAISON ANA screen (91.2% of agreement). After resolution of discrepant results, the concordance reached, respectively, 94.9% and 98.8%. The specificity was 99.3% and the sensitivity was 94%. Unlike results obtained by other ANA screening assays, we observed acceptable sensitivity and specificity. Despite the presence of HEp-2 cell extract, we failed to detect some antibodies as antinucleolar, antinuclear envelope, and antiproliferating cell nuclear antigen. This automated assay allows quick process to results and exhibits satisfactory sensitivity for the detection of the main ANA specificities of connective tissue diseases.

  19. Comparison of five commercial enzyme-linked immunosorbent assays for detection of antibodies to Bordetella pertussis.

    Science.gov (United States)

    Kösters, K; Riffelmann, M; Dohrn, B; von König, C H

    2000-05-01

    Measuring antibodies to Bordetella pertussis antigens is mostly done by enzyme-linked immunosorbent assays (ELISAs). We compared the performance of five commercially available ELISA kits with the help of 65 serum specimens which were repetitively tested for evaluation of the kits. The specimens contained 20 paired serum samples from patients with clinical pertussis, 15 samples were from children vaccinated with a diphtheria-tetanus-acellular pertussis vaccine, seven specimens were taken from an interlaboratory comparison of ELISAs, and there were three reference preparations from the Food and Drug Administration's (FDA's) Laboratory of Pertussis and from our laboratory. Reference values were obtained from the FDA or from results obtained with an in-house ELISA. Commercial ELISAs were compared with respect to their reproducibility and variability, their ability to detect significant titer rises in paired serum samples, their ability to detect an immune response after vaccination, and the comparability of semiquantitative and quantitative results. Reproducibility was generally good (>89%), intra-assay variation ranged from 2.4 to 28.7%, and indeterminate results were recorded in up to 18.5% of all specimens. Most kits correctly identified the antibody response to an acellular pertussis vaccine. None of the commercial kits identified all cases of pertussis correctly, and the sensitivity ranged between 60 and 95%. All five commercial ELISAs showed great discrepancies when comparing semiquantitative results and contained obviously different antigen preparations. Our data suggest that the five commercial ELISAs tested here need further improvement and standardization.

  20. Development of a Coxsackievirus A16 neutralization assay based on pseudoviruses for measurement of neutralizing antibody titer in human serum.

    Science.gov (United States)

    Jin, Jun; Ma, Hongxia; Xu, Lin; An, Dong; Sun, Shiyang; Huang, Xueyong; Kong, Wei; Jiang, Chunlai

    2013-02-01

    Serum neutralizing antibody titers are indicative of protective immunity against Coxsackievirus A16 (CV-A16) and Enterovirus 71 (EV71), the two main etiological agents of hand, foot and mouth disease (HFMD), and provide the basis for evaluating vaccine efficacy. The current CV-A16 neutralization assay based on inhibition of cytopathic effects requires manual microscopic examination, which is time-consuming and labor-intensive. In this study, a high-throughput neutralization assay was developed by employing CV-A16 pseudoviruses expressing luciferase for detecting infectivity in rhabdomyosarcoma (RD) cells and measuring serum viral neutralizing antibodies. Without the need to use infectious CV-A16 strains, the neutralizing antibody titer against CV-A16 could be determined within 15h by measuring luciferase signals by this assay. The pseudovirus CV-A16 neutralization assay (pCNA) was validated by comparison with a conventional CV-A16 neutralization assay (cCNA) in testing 174 human serum samples collected from children (age <5 years). The neutralizing antibody titers determined by these two assays were well correlated (R(2)=0.7689). These results suggest that the pCNA can serve as a rapid and objective procedure for the measurement of neutralizing antibodies against CV-A16.

  1. Accurate and High-Coverage Immune Repertoire Sequencing Reveals Characteristics of Antibody Repertoire Diversification in Young Children with Malaria

    Science.gov (United States)

    Jiang, Ning

    Accurately measuring the immune repertoire sequence composition, diversity, and abundance is important in studying repertoire response in infections, vaccinations, and cancer immunology. Using molecular identifiers (MIDs) to tag mRNA molecules is an effective method in improving the accuracy of immune repertoire sequencing (IR-seq). However, it is still difficult to use IR-seq on small amount of clinical samples to achieve a high coverage of the repertoire diversities. This is especially challenging in studying infections and vaccinations where B cell subpopulations with fewer cells, such as memory B cells or plasmablasts, are often of great interest to study somatic mutation patterns and diversity changes. Here, we describe an approach of IR-seq based on the use of MIDs in combination with a clustering method that can reveal more than 80% of the antibody diversity in a sample and can be applied to as few as 1,000 B cells. We applied this to study the antibody repertoires of young children before and during an acute malaria infection. We discovered unexpectedly high levels of somatic hypermutation (SHM) in infants and revealed characteristics of antibody repertoire development in young children that would have a profound impact on immunization in children.

  2. Label free checkerboard assay to determine overlapping epitopes of Ebola virus VP-40 antibodies using surface plasmon resonance.

    Science.gov (United States)

    Anderson, George P; Liu, Jinny L; Zabetakis, Dan; Legler, Patricia M; Goldman, Ellen R

    2017-03-01

    Immunoassay formats, in which antibodies provide sensitivity and specificity, are often utilized to provide rapid and simple diagnostic tests. Surface plasmon resonance is frequently used to evaluate the suitability of antibodies by determining binding kinetics to agents or surrogate antigens. We used SPR to evaluate a number of commercial monoclonal antibodies as well as single domain antibodies produced in-house. All the antibodies targeted the Ebola virus viral protein 40 (VP40). We determined the ability of each antibody to bind to immobilized VP40, and ensured they did not bind Ebola glycoprotein or the nucleoprotein. A subset of the monoclonal antibodies was immobilized to characterize antigen capture in solution. It can be advantageous to utilize antibodies that recognize distinct epitopes when choosing reagents for detection and diagnostic assays. We determined the uniqueness of the epitope recognized by the anti-VP40 antibodies using a checkerboard format that exploits the 6×6 array of interactions monitored by the Bio-Rad ProteOn XPR36 SPR instrument. The results demonstrate the utility of surface plasmon resonance to characterize monoclonal and recombinant antibodies. Additionally, the analysis presented here enabled the identification of pairs of anti-VP40 antibodies which could potentially be utilized in sandwich type immunoassays for the detection of Ebola virus.

  3. Fluorescent competitive assay for melamine using dummy molecularly imprinted polymers as antibody mimics

    Institute of Scientific and Technical Information of China (English)

    DU Xin-wei; JIN Mao-jun; ZHENG Lu-fei; ZHANG Yan-xin; SHE Yong-xin; LIU Guang-yang; ZHAO Feng-nian; WANG Jing; WANG Shan-shan; JIN Fen; SHAO Hua

    2016-01-01

    A lfuorescent competitive assay for melamine was ifrst developed utilizing dummy molecularly imprinted polymers (DMIPs) as artiifcial antibodies. This method is based on the competition between lfuorescent substances and the unlabeled analyte for binding sites in synthesized DMIPs and the decreased binding of lfuorescent substances to DMIPs due to increased concentrations of melamine in the solutions. DMIPs for melamine were synthesized under a hot water bath in the pres-ence of the initiator azobisisobutyronitrile (AIBN) using 2,4-diamino-6-methyl-1,3,5-triazine (DAMT) as a dummy template, methacrylic acid (MAA) as a functional monomer, and ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent. The adsorption capacity and selectivity of DMIPs for melamine were evaluated by the isothermal adsorption curve and Scatchard analysis. The evaluation results showed that the synthesized DMIPs had speciifc recognition sites for melamine and the maximum adsorption amount was 1066.33 μg g–1. Later, 5-(4,6-dichlorotriazinyl) amino lfuorescein (DTAF) with a triazine ring, which slightly resembles melamine, was selected as the lfuorescent substance. The lfuorescent competitive assay using DMIPs as the antibody mimics was ifnaly established by selecting and optimizing the reaction solvents, DMIPs amount, DTAF concentration, and incubation time. The optimal detection system showed a linear response within range of 0.05–40 mg L–1 and the limit of detection (LOD) was 1.23 μg L–1. It was successfuly applied to the detection of melamine in spiked milk samples with satisfactory recoveries (71.9 to 86.3%). According to the comparative analysis, the result of optimized lfuorescent competitive assay revealed excelent agreement with the HPLC-MS/MS result for melamine.

  4. Accuracy of the Fluorescence-Activated Cell Sorting Assay for the Aquaporin-4 Antibody (AQP4-Ab): Comparison with the Commercial AQP4-Ab Assay Kit

    Science.gov (United States)

    Kim, Yoo-Jin; Cheon, So Young; Kim, Boram; Jung, Kyeong Cheon; Park, Kyung Seok

    2016-01-01

    Background The aquaporin-4 antibody (AQP4-Ab) is a disease-specific autoantibody to neuromyelitis optica (NMO). We aimed to evaluate the accuracy of the FACS assay in detecting the AQP4-Ab compared with the commercial cell-based assay (C-CBA) kit. Methods Human embryonic kidney-293 cells were transfected with human aquaporin-4 (M23) cDNA. The optimal cut off values of FACS assay was tested using 1123 serum samples from patients with clinically definite NMO, those at high risk for NMO, patients with multiple sclerosis, patients with other idiopathic inflammatory demyelinating diseases, and negative controls. The accuracy of FACS assay and C-CBA were compared in consecutive 225 samples that were collected between January 2014 and June 2014. Results With a cut-off value of MFIi of 3.5 and MFIr of 2.0, the receiver operating characteristic curve for the FACS assay showed an area under the curve of 0.876. Among 225 consecutive sera, the FACS assay and C-CBA had a sensitivity of 77.3% and 69.7%, respectively, in differentiating the sera of definite NMO patients from sera of controls without IDD or of MS. Both assay had a good specificity of 100% in it. The overall positivity of the C-CBA among FACS-positive sera was 81.5%; moreover, its positivity was low as 50% among FACS-positive sera with relatively low MFIis. Conclusions Both the FACS assay and C-CBA are sensitive and highly specific assays in detecting AQP4-Ab. However, in some sera with relatively low antibody titer, FACS-assay can be a more sensitive assay option. In real practice, complementary use of FACS assay and C-CBA will benefit the diagnosis of NMO patients, because the former can be more sensitive among low titer sera and the latter are easier to use therefore can be widely used. PMID:27658059

  5. Antibodies with specificity for native and denatured forms of ovalbumin differ in reactivity between enzyme-linked immunosorbent assays

    DEFF Research Database (Denmark)

    Holm, B.E.; Bergmann, A.C.; Hansen, Paul Robert

    2015-01-01

    In this study, polyclonal and monoclonal antibodies to native and denatured chicken ovalbumin (OVA) were produced to compare their dependency on continuous and three-dimensional epitopes. These antibodies were characterized with respect to reactivity to native and denatured OVA by enzyme...... to native OVA reacted strongly with native and denatured OVA in both assays, but did not react with the overlapping peptides. Polyclonal antibodies to denatured OVA reacted strongly with both OVA forms and with several of the overlapping peptides. Monoclonal antibodies to native OVA reacted preferentially...... with three-dimensional epitopes on native OVA and not with denatured OVA. Monoclonal antibodies to denatured OVA showed reactivity to both OVA forms. Two of these monoclonal antibodies, HYB 94-06 and 94-07, showed reactivity to overlapping peptides and their epitopes were identified as flexible structures...

  6. A comparison of a solid phase IRC assay and the PSIFT for detection of antibodies to platelets.

    Science.gov (United States)

    Häcker-Shahin, B; Giannitsis, D J

    1992-01-01

    A rapid solid phase indicator red cells assay (IRCA) for detection of platelet antibodies was developed and its sensitivity compared with PSIFT. Platelets were attached to the surface of polystyrene microtitre plate wells by means of a sodium carbonate buffer and centrifugation. Uncovered areas were blocked by a gelatin blocking buffer. After serum incubation bound platelet-specific antibodies were made visible by anti-IgG-coated indicator red cells and a brief centrifugation. A positive result, meaning the presence of an anti-platelet antibody was indicated by red cell adherence over the reaction surface. In the absence of serum antibodies to platelets the indicator red cells formed a pellet. The IRCA showed a high sensitivity; the anti-platelet antibody Thrombocyte was detectable until a dilution of 1:1,600 whereas the same antibody in the PSIFT could only be detected until a dilution of 1:400.

  7. Comparison of two enzyme-linked immunosorbent assays and one rapid immunoblot assay for detection of herpes simplex virus type 2-specific antibodies in serum

    NARCIS (Netherlands)

    J. Groen (Jan); G. van Dijk (Grietje); H.G.M. Niesters (Bert); W.I. van der Meijden (Willem); A.D.M.E. Osterhaus (Albert)

    1998-01-01

    textabstractThe sensitivities and specificities of three immunoassays for the detection of herpes simplex virus type 2 (HSV-2)-specific immunoglobulin G antibodies in serum, including the one-strip rapid immunoblot assay (RIBA; Chiron Corporation) and two indirect enzyme

  8. Sensitive measurement of thrombopoietin by a monoclonal antibody based sandwich enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Folman, C C; von dem Borne, A E; Rensink, I H; Gerritsen, W; van der Schoot, C E; de Haas, M; Aarden, L

    1997-10-01

    In this report a sensitive enzyme-linked immunosorbent assay (ELISA) for the measurement of plasma thrombopoietin (Tpo) is described that is solely based on monoclonal antibodies (MoAbs). The assay has an intra and inter-assay variance of 5-7% and 7-13%, respectively. Native and recombinant human Tpo (rhTpo) were recognized equally well, no cross reactivity with other cytokines was found and rhTpo added to plasma and serum was completely recovered. With the ELISA, Tpo concentrations in EDTA-anticoagulated plasma of all controls (n = 193) could be determined, since the limit of detection (2 +/- 0.8 A.U./ml, mean +/- sd) was lower than the concentration found in controls (11 +/- 8 A.U./ml, mean +/- sd; 2.5th-97.5th percentile: 4-32 A.U./ml). Tpo levels in serum were on average 3.4 times higher than in plasma. We showed in vivo that Tpo is bound by platelets, as in thrombocytopenic patients (n = 5) a platelet transfusion immediately led to a drop in plasma Tpo level, whereas in patients receiving chemotherapy the induced thrombocytopenia was followed by a rise in plasma Tpo levels. In summary, these results indicate that this ELISA is a reliable tool for Tpo measurements and is applicable for large scale studies.

  9. Antiphospholipid antibody syndrome: the flow cytometric annexin A5 competition assay as a diagnostic tool.

    Science.gov (United States)

    Tomer, A; Bar-Lev, S; Fleisher, S; Shenkman, B; Friger, M; Abu-Shakra, M

    2007-10-01

    The mechanism underlying hypercoagulability in antiphospholipid antibody syndrome (APS) is uncertain. Here, we present a flow-cytometric assay (FCA) based on the hypothesis that anti-platelet-anionic-phospholipid autoantibodies (aPL) interfere with the activity of the natural anticoagulant protein annexin A5, thereby accelerating platelet procoagulant activity. This study assessed the clinical utility of the feasible FCA, which demonstrates the competition of the patient's aPL with the binding of annexin A5 to the platelet-anionic-phospholipids, in the diagnosis of APS. Sixty-two (94%) of 66 APS patients, 20 (51%) of 39 patients with systemic lupus erythematosus and two (4%) of 49 healthy individuals were positive by FCA. Compared with the anticardiolipin (aCL) assay, the relative sensitivity was 82% and the specificity 73.3%. However, 19 (25%) aCL-negative patients were positive by FCA; 12 were positive for lupus-anticoagulant (LA). Compared with LA assay, the relative sensitivity was 85% and the specificity 72.2%. However, 21 (26%) LA-negative patients were FCA-positive, 12 were positive for aCL. The FCA was particularly sensitive for APS patients with arterial (97.0%) and gestational vascular complications (100%) with overall sensitivity of 95% and specificity of 97%. Our findings suggest that the FCA is practical, sensitive and specific for the detection of clinically relevant aPL in the diagnosis of APS.

  10. Challenges for bovine viral diarrhoea virus antibody detection in bulk milk by antibody enzyme-linked immunosorbent assays due to changes in milk production levels

    DEFF Research Database (Denmark)

    Foddai, Alessandro; Enøe, Claes; Stockmarr, Anders

    2015-01-01

    Background: Bovine viral diarrhoea (BVD) is considered eradicated from Denmark. Currently, very few (if any) Danish cattle herds could be infected with BVD virus (BVDV). The Danish antibody blocking enzyme-linked immunosorbent assay (ELISA) has been successfully used during the Danish BVD eradica...

  11. The development of an Enzyme Linked Immunosorbent Assay for detecting Injectious laryngotrachitis viral antibodies in chicken serum

    Directory of Open Access Journals (Sweden)

    Risa Indriani

    2002-06-01

    Full Text Available The aim of this study was to develop an Enzyme-linked immunosorbent assay (ELISA for detection of antibody against gallid herpes virus, the causal agent of infectious laryngotracheitis (ILT in chicken. Its application in experimental chicken under laboratory condition was also evaluated. Results showed that ELISA for ILT was developed successfully with sensitivity and specificity was 98% and 97,14% respectively. The ELISA was able to determine the dynamic of antibodies respond in experimental chickens following vaccination and artificial infection with ILT virus. It was concluded that this ELISA offers a simple, sensitive and specific antibody assay for detection of antibodies against ILT virus in chickens arising from vaccination or infection.

  12. A Comparison of Anti-Nuclear Antibody Quantification Using Automated Enzyme Immunoassays and Immunofluorescence Assays

    DEFF Research Database (Denmark)

    Baronaite, Renata; Engelhart, Merete; Mørk Hansen, Troels;

    2014-01-01

    Anti-nuclear antibodies (ANA) have traditionally been evaluated using indirect fluorescence assays (IFA) with HEp-2 cells. Quantitative immunoassays (EIA) have replaced the use of HEp-2 cells in some laboratories. Here, we evaluated ANA in 400 consecutive and unselected routinely referred patients...... patients were compared. The majority of the results were the same between the two methods (n = 325, 84%); however, 8% (n = 30) yielded equivocal results (equivocal-negative and equivocal-positive) and 8% (n = 31) yielded divergent results (positive-negative). The results showed fairly good agreement......, with Cohen's kappa value of 0.30 (95% confidence interval (CI) = 0.14-0.46), which decreased to 0.23 (95% CI = 0.06-0.40) when the results for dsDNA were omitted. The EIA method was less reliable for assessing nuclear and speckled reactivity patterns, whereas the IFA method presented difficulties detecting...

  13. Monoclonal Antibody-Based Enzyme Linked Immunosorbent Assay for the Analysis of Jasmonates in Plants

    Institute of Scientific and Technical Information of China (English)

    Aixing Deng; Weiming Tan; Suping He; Wei Liu; Tiegui Nan; Zhaohu Li; Baomin Wang; Qing X.Li

    2008-01-01

    Methyl jasmonate (MeJA) and its free-acid form,jasmonic acid (JA) are naturally occurring plant growth regulators widely distributed in higher plants.In order to improve the sensitivity for the analysis of MeJA at low levels in small amounts of plant samples,a monoclonal antibody (MAb) (designated as MAb 3E5D7C4B6) against MeJA was derived from a JAbovine serum albumin (BSA) conjugate as an immunogen.The antibody belongs to the IgG1 subclass with a κ type light chain and has a dissociation constant of approximately 6.07 x 10-9 M.MAb3E5D7C4B6 is very specific to MeJA.It was used to develop a direct competitive enzyme-linked immunosorbent assay (dcELISA),conventional and simplified indirect competitive ELISAs (icELISA).JA was derivatized into MeJA for the ELISA analysis.The IC50 value and detection range for MeJA were,respectively,34 and 4-257 ng/mL by the conventional icELISA,21 and 3-226 ng/mL by the simplified icELISA and 5.0 and 0.7-97.0 ng/mL by the dcELISA.The dcELISA was more sensitive than either the conventional or simplified icELISA.The assays were used to measure the content of jasmonates as MeJA in tobacco leaves under drought stress or inoculated with tobacco mosaic virus and tomato leaves inoculated with tomato mosaic virus or Lirioinyza sativae Blanchard as compared with the corresponding healthy leaves.The increased jasmonates content indicated its role in response to the drought stress and pathogens.

  14. Evaluation of a pan-serotype point-of-care rapid diagnostic assay for accurate detection of acute dengue infection.

    Science.gov (United States)

    Vivek, Rosario; Ahamed, Syed Fazil; Kotabagi, Shalini; Chandele, Anmol; Khanna, Ira; Khanna, Navin; Nayak, Kaustuv; Dias, Mary; Kaja, Murali-Krishna; Shet, Anita

    2017-03-01

    The catastrophic rise in dengue infections in India and globally has created a need for an accurate, validated low-cost rapid diagnostic test (RDT) for dengue. We prospectively evaluated the diagnostic performance of NS1/IgM RDT (dengue day 1) using 211 samples from a pediatric dengue cohort representing all 4 serotypes in southern India. The dengue-positive panel consisted of 179 dengue real-time polymerase chain reaction (RT-PCR) positive samples from symptomatic children. The dengue-negative panel consisted of 32 samples from dengue-negative febrile children and asymptomatic individuals that were negative for dengue RT-PCR/NS1 enzyme-linked immunosorbent assay/IgM/IgG. NS1/IgM RDT sensitivity was 89.4% and specificity was 93.8%. The NS1/IgM RDT showed high sensitivity throughout the acute phase of illness, in primary and secondary infections, in different severity groups, and detected all 4 dengue serotypes, including coinfections. This NS1/IgM RDT is a useful point-of-care assay for rapid and reliable diagnosis of acute dengue and an excellent surveillance tool in our battle against dengue. Copyright © 2016. Published by Elsevier Inc.

  15. Evaluation of antiphospholipid antibody assays using latent class analysis to address the lack of a reference standard.

    Science.gov (United States)

    Thaler, Markus A; Bietenbeck, Andreas; Yin, Meng-Xin; Steigerwald, Udo; Holmes, Andrew B; Lindhoff-Last, Edelgard; Luppa, Peter B

    2016-12-01

    Method evaluation of new assays for the detection of antiphospholipid antibodies (aPL) such as anti-cardiolipin (aCL) or anti-β2-glycoprotein I (aβ2-GPI) is challenging, as no internationally accepted reference material is available yet. Besides a lack of standardization, unacceptable inter-laboratory comparability of established tests is regularly observed. Owing to the absence of a commonly accepted reference standard, the evaluation of two research surface plasmon resonance (SPR) biosensor assays was performed using statistical methods from latent class analysis (LCA). aCL and aβ2-GPI IgG and IgM were measured in sera from 63 antiphospholipid syndrome patients, fulfilling the Sydney criteria, and in 34 healthy controls with four commercial assays. LCA was performed on the results and sera were assigned to the antibody-positive or antibody-negative group. Sera were subsequently evaluated in the SPR assays for aCL and aβ2-GPI. Optimal cutoffs and diagnostic performances of the research systems were established employing the LCA-derived gold standard. With area under the curve results of 0.96 and 0.89 for the detection of aCL and aβ2-GPI, the research SPR assays discriminated well between antibody-positive and antibody-negative sera. Their sensitivities and specificities were comparable to the investigated commercial immunoassays. SPR assays are a suitable tool for the detection of aCL and aβ2-GPI with diagnostic performances not different from currently available commercial tests. LCA enabled the calculation of sensitivities and specificities for aPL assays in absence of a reference standard.

  16. Modification of solid phase red cell adherence assay for the detection of platelet antibodies in patients with thrombocytopenia.

    Science.gov (United States)

    Vongchan, Preeyanat; Nawarawong, Weerasak; Linhardt, Robert J

    2008-09-01

    Platelet refractoriness is caused by HLA antibodies and platelet-specific antibodies. Current methods used to detect antiplatelet antibodies have limitations. Solid phase red cell adherence (SPRCA) lacks sensitivity and requires a second assay using chloroquine-treated intact platelets to specify the response due to anti-HLA. We modified SPRCA by using 2 types of antihuman platelet antibodies with different specificities toward platelet lysate and tested samples from 361 patients (69 with unexplained thrombocytopenia and 292 with poor response to platelet transfusions not explicable by alloimmunization or the clinical situation) and 50 from healthy volunteers. Our method compared favorably with platelet suspension direct immunofluorescence. All samples from healthy volunteers were negative; of the samples from the patient population, 240 were positive (147 samples had only antiplatelet and 3 samples had only anti-HLA antibodies). This modified technique had a sensitivity of 98% and a specificity of 91%.

  17. Dot-immunobinding assay with monoclonal antibody for detection of Trichomonas vaginalis in clinical specimens.

    Science.gov (United States)

    Gombosová, A; Valent, M

    1990-01-01

    A rapid and specific dot-enzyme immunoassay (DIBA) using monoclonal antibody was introduced for detection of Trichomonas vaginalis antigen in vaginal and urethral materials. The results of DIBA were compared with culture findings of the parasite in 245 female patients. Taking culture as the reference method, DIBA had a sensitivity of 92% and a specificity of 93%. The predictive value of a positive test was 98% and that of a negative test 77%. The efficacy of wet mount, culture and DIBA were compared in 134 women with trichomonal infection. The most sensitive method was cultivation with a positivity of 99.3%. DIBA was as sensitive as the wet mount (92%). In 51 sexual partners of women with trichomoniasis DIBA proved to be ineffective. The sensitivity of the assay with corpuscular antigen of T vaginalis was 1 x 10(4) cells/ml, with soluble antigen 47 micrograms/ml. Specificity of the assay was confirmed by lack of any cross-reactivity with Trichomonas tenax. Tritrichomonas mobilensis and Candida albicans. Images PMID:2265844

  18. A rugged, precise and accurate new gravimetry method for the determination of gold: an alternative to fire assay method.

    Science.gov (United States)

    Singh, Nahar

    2012-01-01

    A new, rugged, precise, accurate and fast primary method of measurement has been proposed for the determination of gold in various gold articles. Precise and accurate measurement of gold is the primary requirement for hall marking and to trade gold internationally, as billions of dollars of gold are trading world wide for the various applications. At present Fire Assay ASTM E 1335-08 is the only Standard Test Method for the determination of Gold, which is accepted internationally. But the method is time consuming, cumbersome and required expertise to perform the test. In the present investigation, a method has been developed gravimetry based on direct determination of gold after reducing gold in zero-valent state by hydroxylamine hydrochloride. Gravimetry is the most reliable technique and having highest metrological qualities in comparison to titremetry and instrumental method and the results of gravimetry are directly traceable to SI unit. The results of gravimetric method are accepted without reference to a standard of the same quantity. Several experiments were carried out with and without impurities and it has been concluded that gold can be determined accurately and precisely in presence of several impurities. Five replicates of approximate 0.2 g gold samples were analyzed following method proposed and percentage purity were found to be 99.993 ± 0.0056 with 95% confidence level (k = 2). The combined uncertainty in gold measurement has also been evaluated using potential sources of the method according to the EURACHEM/GUM guidelines.

  19. Comparison of competitive ligand-binding assay and bioassay formats for the measurement of neutralizing antibodies to protein therapeutics.

    Science.gov (United States)

    Finco, Deborah; Baltrukonis, Daniel; Clements-Egan, Adrienne; Delaria, Kathy; Gunn, George R; Lowe, John; Maia, Mauricio; Wong, Teresa

    2011-01-25

    Administration of biological therapeutic proteins can lead to unwanted immunogenicity in recipients of these products. The assessment and characterization of such immune reactions can be helpful to better understand their clinical relevance and how they relate to patient safety and therefore, have become an integral part of a product development program for biological therapeutics. Testing for anti-drug antibodies (ADA) to biological/biotechnology-derived therapeutic proteins generally follows a tiered approach. Samples are initially screened for binding antibodies; presumptive positives are then confirmed in a confirmatory assay; subsequently, confirmed-positive samples may be further characterized by titration and with a neutralizing antibody (NAb) assay. Regulatory guidances on immunogenicity state that assessing the neutralizing capacity of antibodies should preferably be done using functional bioassays, while recognizing that competitive ligand-binding (CLB) assays may be substituted when neutralizing bioassays are inadequate or not feasible. This manuscript describes case studies from four companies in which CLB assays and functional bioassays were compared for their ability to detect neutralizing ADA against a variety of biotechnology-derived therapeutic proteins. Our findings indicate that CLB assays are comparable to bioassays for the detection of NAbs, in some cases offering better detection sensitivity, lower variability, and less matrix interference.

  20. Preparation of Monoclonal Antibodies and a Simple Myeloperoxidase-Immunosorbent Assay for Detecting Human Myeloperoxidase.

    Science.gov (United States)

    Bian, Zhi-Ping; Li, Xiong-Zhi; Wu, Heng-Fang; Xu, Jin-Dan; Gu, Chun-Rong; Chen, Xiang-Jian; Yang, Di

    2016-04-01

    Myeloperoxidase (MPO), a leukocyte hemoprotein released from neutrophils, is thought to be a potential participant in plaque formation and plaque rupture. Therefore, MPO is regarded as an early marker predicting the risk for atherosclerosis, especially for coronary artery disease and acute coronary syndrome. We generated hybridoma clones 1E3 and 3E8 secreting monoclonal antibodies (mAbs) specific to human MPO. BALB/c mice were immunized with MPO protein purified from human neutrophils. Splenocytes from these mice were fused with the mouse myeloma cell line SP2/0. Based on isotyping of the mAbs, both clones 1E3 and 3E8 were referred to the IgG1 subclass. The specificities of 1E3 and 3E8 were assessed by enzyme-linked immunosorbent assay (ELISA), and only 3E8 was confirmed by western blot. We developed a simple MPO-immunosorbent assay (MPO-ISA) on microplate based on both the immune activity and peroxidase activity of MPO. The mAb secreted by clone 3E8 was chosen as coating antibody to capture the plasma MPO without interfering with the peroxidase activity of MPO. Then, tetramethylbenzidine substrate was added to the microwell directly, catalyzed by captured MPO, and a colored product was formed. The simple MPO-ISA test has a sensitivity of 3.68 ng/mL. The linear concentration of MPO-ISA for commercial MPO standard ranged to 250 ng/mL. The average recovery rate is 101.02%. The imprecision within-day was ISA can detect the plasma MPO from human and cavy, but not from mouse and rat. Compared with the commercial human MPO ELISA assay, the MPO-ISA can be used to detect the natural human MPO protein, but not recombinant MPO polypeptides. The generated mAbs and MPO-ISA test may be useful tools to assess risk for inflammation and cardiac events.

  1. Validation of 2 commercial Neospora caninum antibody enzyme linked immunosorbent assays.

    Science.gov (United States)

    Wu, John T Y; Dreger, Sally; Chow, Eva Y W; Bowlby, Evelyn E

    2002-10-01

    This is a validation study of 2 commercially available enzyme linked immunosorbent assays (ELISA) for the detection of antibodies against Neospora caninum in bovine serum. The results of the reference sera (n = 30) and field sera from an infected beef herd (n = 150) were tested by both ELISAs and the results were compared statistically. When the immunoblotting results of the reference bovine sera were compared to the ELISA results, the same identity score (96.67%) and kappa values (K) (0.93) were obtained for both ELISAs. The sensitivity and specificity values for the IDEXX test were 100% and 93.33% respectively. For the Biovet test 93.33% and 100% were obtained. The corresponding positive (PV+) and negative predictive (PV-) values for the 2 assays were 93.75% and 100% (IDEXX), and 100% and 93.75% (Biovet). In the 2nd study, competitive inhibition ELISA (c-ELISA) results on bovine sera from an infected herd were compared to the 2 sets of ELISA results. The identity scores of the 2 ELISAs were 98% (IDEXX) and 97.33% (Biovet). The K values calculated were 0.96 (IDEXX) and 0.95 (Biovet). For the IDEXX test the sensitivity and specificity were 97.56% and 98.53%, whereas for the Biovet assay 95.12% and 100% were recorded, respectively. The corresponding PV+ and PV- values were 98.77% and 97.1% (IDEXX), and 100% and 94.44% (Biovet). Our validation results showed that the 2 ELISAs worked equally well and there was no statistically significant difference between the performance of the 2 tests. Both tests showed high reproducibility, repeatability and substantial agreement with results from 2 other laboratories. A quality assurance based on the requirement of the ISO/IEC 17025 standards has been adopted throughout this project for test validation procedures.

  2. Validation of 2 commercial Neospora caninum antibody enzyme linked immunosorbent assays

    Science.gov (United States)

    Wu, John T.Y.; Dreger, Sally; Chow, Eva Y.W.; Bowlby, Evelyn E.

    2002-01-01

    Abstract This is a validation study of 2 commercially available enzyme linked immunosorbent assays (ELISA) for the detection of antibodies against Neospora caninum in bovine serum. The results of the reference sera (n = 30) and field sera from an infected beef herd (n = 150) were tested by both ELISAs and the results were compared statistically. When the immunoblotting results of the reference bovine sera were compared to the ELISA results, the same identity score (96.67%) and kappa values (K) (0.93) were obtained for both ELISAs. The sensitivity and specificity values for the IDEXX test were 100% and 93.33% respectively. For the Biovet test 93.33% and 100% were obtained. The corresponding positive (PV+) and negative predictive (PV−) values for the 2 assays were 93.75% and 100% (IDEXX), and 100% and 93.75% (Biovet). In the 2nd study, competitive inhibition ELISA (c-ELISA) results on bovine sera from an infected herd were compared to the 2 sets of ELISA results. The identity scores of the 2 ELISAs were 98% (IDEXX) and 97.33% (Biovet). The K values calculated were 0.96 (IDEXX) and 0.95 (Biovet). For the IDEXX test the sensitivity and specificity were 97.56% and 98.53%, whereas for the Biovet assay 95.12% and 100% were recorded, respectively. The corresponding PV+ and PV− values were 98.77% and 97.1% (IDEXX), and 100% and 94.44% (Biovet). Our validation results showed that the 2 ELISAs worked equally well and there was no statistically significant difference between the performance of the 2 tests. Both tests showed high reproducibility, repeatability and substantial agreement with results from 2 other laboratories. A quality assurance based on the requirement of the ISO/IEC 17025 standards has been adopted throughout this project for test validation procedures. PMID:12418782

  3. [Measurement of thyrotropin receptor antibodies (TRAK) with a second generation assay in patients with Graves' disease].

    Science.gov (United States)

    Zöphel, K; Wunderlich, G; Koch, R; Franke, W G

    2000-01-01

    The detection of TSH-receptor-antibodies (TRAb) in patients (pts) with Graves' disease (GD) is routinely used in nuclear medicine laboratories. It is performed by commercial, porcine radioreceptorassays (RRA) measuring TSH binding inhibitory activity. A second generation assay using the human, recombinant TSH-receptor was developed during the last years. The manufacturer composed this new assay as a coated tube RRA (CT RRA) and claimed a higher sensitivity for GD. TRAb was measured in 207 pts with various thyroid disorders and 205 healthy controls using the new coated tube RRA (Fa. B.R.A.H.M.S. Diagnostica GmbH, Berlin, Germany) as well as a conventional RRA (Fa. Medipan Diagnostica GmbH, Selchow, Germany): 60 pts suffering from GD showing a relapse after antithyroid drug treatment and before radioiodine therapy, 109 pts with disseminated autonomia (DA) and 38 pts suffering from Hashimoto's thyroiditis. A ROC-analysis was performed to find the optimal decision threshold level for positivity. We found 42/60 TRAb-positive pts with GD in the established RRA (threshold 6 U/L) and 52/60 in the CT RRA, respectively. The sensitivity increased from 70% (RRA) to 86.7% (CT RRA). The CT RRA found 2 false positives (one Hashimoto's and one healthy control) and the RRA detected 3 Hashimoto's and 2 healthy controls as false positive. The increased sensitivity of CT RRA for GD provides an advantage compared to conventional RRA, especially in GD-patients relapsing after antithyroid drug treatment. Functional sensitivity and Interassay-variation of CT RRA are very precisely compared to conventional RRA. Handling of the new assay is also improved.

  4. Enzyme-linked immunosorbent assay for total isoflavonoids in Pueraria candollei using anti-puerarin and anti-daidzin polyclonal antibodies.

    Science.gov (United States)

    Pongkitwitoon, Benyakan; Sakamoto, Seiichi; Tanaka, Hiroyuki; Tsuchihashi, Ryota; Kinjo, Junei; Morimoto, Satoshi; Putalun, Waraporn

    2010-05-01

    Pueraria candollei (White Kwao Khuer) is a medicinal plant containing puerarin, daidzin, genistin, daidzein, and genistein as major isoflavonoids used for its rejuvenating and estrogenic effects. In order to analyze these compounds, a single enzyme-linked immunosorbent assay (ELISA) for total isoflavonoids was developed using anti-puerarin and anti-daidzin polyclonal antibodies (PAbs). The range for calibration of isoflavonoids by ELISA was 0.05-6.25 microg/mL. Total isoflavonoid concentrations in P. candollei samples determined by the newly developed assay system showed good agreement with those analyzed by HPLC. Based on validation analysis, this analytical method by ELISA is a precise, accurate, and sensitive method for the determination of total isoflavonoids in P. candollei.

  5. Simultaneous determination of soy isoflavone glycosides, daidzin and genistin by monoclonal antibody-based highly sensitive indirect competitive enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Sakamoto, Seiichi; Yusakul, Gorawit; Pongkitwitoon, Benyakan; Paudel, Madan Kumar; Tanaka, Hiroyuki; Morimoto, Satoshi

    2015-02-15

    Soy isoflavones are known as major bioactive compounds in soybean (Glycine max), which is an indispensable food. Despite their utility, the consumption of isoflavones has recently been limited because they exhibit oestrogenic and topoisomerase II inhibitory effects. To assess their intake limitation, accurate, sensitive, and effective quantitative analyses are necessary. In this study, we produced the monoclonal antibody (MAb) against daidzin (DZ) and applied it to an indirect competitive enzyme-linked immunosorbent assay (icELISA) for the simultaneous determination of DZ and genistin (GEN), which are known as two major soy isoflavone glycosides in soy products. Using the DZ-MAb, we developed a sensitive icELISA method, where the limit of detection for DZ and GEN was 1.95ng/ml. Several validation analyses revealed that the icELISA is sufficiently accurate and sensitive to be used to assess the overconsumption of soy isoflavones, which would lead to the safe dietary intake of soy products.

  6. Development and evaluation of a blocking enzyme-linked immunosorbent assay and virus neutralization assay to detect antibodies to viral hemorrhagic septicemia virus

    Science.gov (United States)

    Wilson, Anna; Goldberg, Tony; Marcquenski, Susan; Olson, Wendy; Goetz, Frederick; Hershberger, Paul; Hart, Lucas M.; Toohey-Kurth, Kathy

    2014-01-01

    Viral hemorrhagic septicemia virus (VHSV) is a target of surveillance by many state and federal agencies in the United States. Currently, the detection of VHSV relies on virus isolation, which is lethal to fish and indicates only the current infection status. A serological method is required to ascertain prior exposure. Here, we report two serologic tests for VHSV that are nonlethal, rapid, and species independent, a virus neutralization (VN) assay and a blocking enzyme-linked immunosorbent assay (ELISA). The results show that the VN assay had a specificity of 100% and sensitivity of 42.9%; the anti-nucleocapsid-blocking ELISA detected nonneutralizing VHSV antibodies at a specificity of 88.2% and a sensitivity of 96.4%. The VN assay and ELISA are valuable tools for assessing exposure to VHSV.

  7. A combination of serological assays to detect human antibodies to the avian influenza A H7N9 virus.

    Directory of Open Access Journals (Sweden)

    Libo Dong

    Full Text Available Human infection with avian influenza A H7N9 virus was first identified in March 2013 and represents an ongoing threat to public health. There is a need to optimize serological methods for this new influenza virus. Here, we compared the sensitivity and specificity of the hemagglutinin inhibition (HI, microneutralization (MN, and Western blot (WB assays for the detection of human antibodies against avian influenza A (H7N9 virus. HI with horse erythrocytes (hRBCs and a modified MN assay possessed greater sensitivity than turkey erythrocytes and the standard MN assay, respectively. Using these assays, 80% of tested sera from confirmed H7N9 cases developed detectable antibody to H7N9 after 21 days. To balance sensitivity and specificity, we found serum titers of ≥20 (MN or 160 (HI samples were most effective in determining seropositive to H7N9 virus. Single serum with HI titers of 20-80 or MN titer of 10 could be validated by each other or WB assay. Unlike serum collected from adult or elderly populations, the antibody response in children with mild disease was low or undetectable. These combinations of assays will be useful in case diagnosis and serologic investigation of human cases.

  8. Flow cytometry-based assay to evaluate human serum MUC1-Tn antibodies

    DEFF Research Database (Denmark)

    Van Elssen, Catharina H M J; Clausen, Henrik; Germeraad, Wilfred T V

    2011-01-01

    to detect antibodies binding to the underglycosylated MUC1 protein. This cellular system is complementary to the previously published methods to detect MUC1 serum antibodies, since the antibodies to the native protein are evaluated and therefore it can be effectively used for MUC1 antibody monitoring...

  9. Diagnosis of Avian bornavirus infection in psittaciformes by serum antibody detection and reverse transcription polymerase chain reaction assay using feather calami.

    Science.gov (United States)

    de Kloet, Arne H; Kerski, Anelle; de Kloet, Siwo R

    2011-05-01

    Avian bornavirus (ABV) is the causative agent of proventricular dilatation disease (PDD), a highly devastating and contagious disease of psittacines (parrots and parakeets), which has resulted in the death of many captive birds. Accurate diagnosis of bornavirus infection is therefore important for the identification and isolation of infected birds. The current study showed that nonvascular contour (chest) feather calami provide a ready and minimally invasive source of RNA for the detection of ABV by reverse transcription polymerase chain reaction (RT-PCR). Storage of the feathers at room temperature for at least a month did not affect the results. Serological analysis by enzyme-linked immunosorbent assay (ELISA) showed that identification of anti-bornaviral nucleoprotein P40 antibodies can identify many birds with a past or present infection. The presence of anti-avian bornaviral P24 phosphoprotein and P16 matrix protein antibodies was quite variable, rendering these antibodies less useful for diagnosis of ABV infection. The significance of the present findings is that the use of nonvascular feathers as a source of RNA allows sample collection under conditions where storage of other samples would be difficult. Serum detection by ELISA of anti-P40 antibodies allows the identification of infected birds when RT-PCR fails. © 2011 The Author(s)

  10. Comparison of a commercial ELISA and an immunoperoxidase monolayer assay to detect antibodies directed against porcine respiratory and reproductive syndrome virus

    NARCIS (Netherlands)

    Nodelijk, G.; Wensvoort, G.; Kroese, B.; Leengoed, van L.A.M.G.; Colijn, E.; Verheijden, J.H.M.

    1996-01-01

    A commercially available enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against porcine respiratory and reproductive syndrome virus (PRRSV) was compared to an immunoperoxidase monolayer assay (IPMA). Serum samples used were collected from pigs experimentally infected with

  11. The diagnosis of proventricular dilatation disease: use of a Western blot assay to detect antibodies against avian Borna virus.

    Science.gov (United States)

    Villanueva, Itamar; Gray, Patricia; Mirhosseini, Negin; Payne, Susan; Hoppes, Sharman; Honkavuori, Kirsi S; Briese, Thomas; Turner, Debra; Tizard, Ian

    2010-07-14

    Avian Borna virus (ABV) has recently been shown to be the causal agent of proventricular dilatation disease (PDD) a lethal neurologic disease of captive psittacines and other birds. An immunoblot assay was used to detect the presence of antibodies against avian Borna virus in the serum of affected birds. A lysate from ABV-infected duck embryo fibroblasts served as a source of antigen. The assay was used to test for the presence of antibodies to ABV in 117 birds. Thirty of these birds had biopsy or necropsy-confirmed proventricular dilatation disease (PDD), while the remaining 87 birds were apparently healthy or were suffering from diseases other than PDD. Sera from 27 of the 30 PDD cases (90%) contained antibodies to ABV. Seventy-three (84%) of the apparently "healthy" birds were seronegative. Additionally, sera from seven macaws and one parrot trapped in the Peruvian Amazon were seronegative. Positive sera recognized the bornaviral nucleoprotein (N-protein). While the presence of antibodies to ABV largely corresponded with the development of clinical PDD, 14 apparently healthy normal birds possessed detectable antibodies to ABV. The existence of a carrier state was confirmed when 13 of 15 apparently healthy cockatiels were shown by PCR to have detectable ABV RNA in their feces. Western blot assays may be of significant assistance in diagnosing proventricular dilatation disease. Many apparently healthy birds may however be seronegative while, at the same time, shedding ABV in their feces. (c) 2009 Elsevier B.V. All rights reserved.

  12. Radiometric cytolysis inhibition assay, a new rapid test for neutralizing antibodies to intact and trypsin-cleaved poliovirus

    Energy Technology Data Exchange (ETDEWEB)

    Hovi, T.; Roivainen, M.

    1989-04-01

    We have developed a new rapid test, the radiometric cytolysis inhibition assay (RACINA), for the determination of neutralizing poliovirus antibodies. HeLa cells prelabeled with /sup 51/Cr, (/sup 3/H)leucine, or, preferentially, with (/sup 3/H)uridine are used as sensitive quantitative indicators of residual infectious virus. Both suspensions and monolayer cultures of the indicator cells can be used. Neutralization of a fraction of a high-titer virus preparation can be scored after the first replication cycle at 8 to 10 h. By lowering the incubation temperature to 30/degree/C, the completion of the cytolysis due to the first replication cycle of poliovirus was delayed beyond 21 h. This makes it possible to use the RACINA, unlike the standard microneutralization assay, for measuring antibodies to trypsin-cleaved polioviruses. The RACINA was found to be as sensitive as and more reproducible than the standard microneutralization assay in the measurement of neutralizing poliovirus antibodies. The RACINA is a rapid and reliable test for neutralizing antibodies and in principle it may be applicable for quantitation of neutralizing antibodies to other cytolytic agents as well.

  13. Gold nanoparticle-based enzyme-linked antibody-aptamer sandwich assay for detection of Salmonella Typhimurium.

    Science.gov (United States)

    Wu, Wenhe; Li, Jun; Pan, Dun; Li, Jiang; Song, Shiping; Rong, Mingge; Li, Zixi; Gao, Jimin; Lu, Jianxin

    2014-10-01

    Enzyme-linked immunosorbent assay (ELISA) provides a convenient means for the detection of Salmonella enterica serovar Typhimurium (STM), which is important for rapid diagnosis of foodborne pathogens. However, conventional ELISA is limited by antibody-antigen immunoreactions and suffers from poor sensitivity and tedious sample pretreatment. Therefore, development of novel ELISA remains challenging. Herein, we designed a comprehensive strategy for rapid, sensitive, and quantitative detection of STM with high specificity by gold nanoparticle-based enzyme-linked antibody-aptamer sandwich (nano-ELAAS) method. STM was captured and preconcentrated from samples with aptamer-modified magnetic particles, followed by binding with detector antibodies. Then nanoprobes carrying a large amount of reporter antibodies and horseradish peroxidase molecules were used for colorimetric signal amplification. Under the optimized reaction conditions, the nano-ELAAS assay had a quantitative detection range from 1 × 10(3) to 1 × 10(8) CFU mL(-1), a limit of detection of 1 × 10(3) CFU mL(-1), and a selectivity of >10-fold for STM in samples containing other bacteria at higher concentration with an assay time less than 3 h. In addition, the developed nanoprobes were improved in terms of detection range and/or sensitivity when compared with two commercial enzyme-labeled antibody signal reporters. Finally, the nano-ELAAS method was demonstrated to work well in milk samples, a common source of STM contamination.

  14. Detection by radioimmunoassay and enzyme-linked immunosorbent assay of coronavirus antibodies in bovine serum and lacteal secretions.

    Science.gov (United States)

    Rodak, L; Babiuk, L A; Acres, S D

    1982-07-01

    The sensitivity of a radioimmunoassay (RIA), an enzyme-linked immunosorbent assay (ELISA), and a serum neutralization assay (SN) for detecting antibodies to bovine coronavirus in serum and colostrum were compared. Although there proved to be a good correlation among all three assays (r = 0.915 and 0.964 for RIA with SN and ELISA, respectively), RIA and ELISA proved to be at least 10 times more sensitive than neutralization tests. By using these techniques, it was possible to detect a time-dependent decrease in antibody levels in bovine colostrum after parturition. Using ELISA, we demonstrated that 12 of 12 herds in Saskatchewan, and 109 of 110 animals tested, and antibody to bovine coronavirus. There was no elevated antibody response in serum or lacteal secretions of cows vaccinated once or twice with a commercially available modified live rota-coronavirus vaccine. In addition to being more sensitive than SN, ELISA and RIA proved to have other advantages for measuring antibody levels to bovine coronavirus and therefore warrant wider use as tools in diagnostic virology.

  15. Antibody performance in ChIP-sequencing assays: From quality scores of public data sets to quantitative certification

    Science.gov (United States)

    Mendoza-Parra, Marco-Antonio; Saravaki, Vincent; Cholley, Pierre-Etienne; Blum, Matthias; Billoré, Benjamin; Gronemeyer, Hinrich

    2016-01-01

    We have established a certification system for antibodies to be used in chromatin immunoprecipitation assays coupled to massive parallel sequencing (ChIP-seq). This certification comprises a standardized ChIP procedure and the attribution of a numerical quality control indicator (QCi) to biological replicate experiments. The QCi computation is based on a universally applicable quality assessment that quantitates the global deviation of randomly sampled subsets of ChIP-seq dataset with the original genome-aligned sequence reads. Comparison with a QCi database for >28,000 ChIP-seq assays were used to attribute quality grades (ranging from ‘AAA’ to ‘DDD’) to a given dataset. In the present report we used the numerical QC system to assess the factors influencing the quality of ChIP-seq assays, including the nature of the target, the sequencing depth and the commercial source of the antibody.  We have used this approach specifically to certify mono and polyclonal antibodies obtained from Active Motif directed against the histone modification marks H3K4me3, H3K27ac and H3K9ac for ChIP-seq. The antibodies received the grades AAA to BBC ( www.ngs-qc.org). We propose to attribute such quantitative grading of all antibodies attributed with the label “ChIP-seq grade”. PMID:27335635

  16. Antibody performance in ChIP-sequencing assays: From quality scores of public data sets to quantitative certification.

    Science.gov (United States)

    Mendoza-Parra, Marco-Antonio; Saravaki, Vincent; Cholley, Pierre-Etienne; Blum, Matthias; Billoré, Benjamin; Gronemeyer, Hinrich

    2016-01-01

    We have established a certification system for antibodies to be used in chromatin immunoprecipitation assays coupled to massive parallel sequencing (ChIP-seq). This certification comprises a standardized ChIP procedure and the attribution of a numerical quality control indicator (QCi) to biological replicate experiments. The QCi computation is based on a universally applicable quality assessment that quantitates the global deviation of randomly sampled subsets of ChIP-seq dataset with the original genome-aligned sequence reads. Comparison with a QCi database for >28,000 ChIP-seq assays were used to attribute quality grades (ranging from 'AAA' to 'DDD') to a given dataset. In the present report we used the numerical QC system to assess the factors influencing the quality of ChIP-seq assays, including the nature of the target, the sequencing depth and the commercial source of the antibody.  We have used this approach specifically to certify mono and polyclonal antibodies obtained from Active Motif directed against the histone modification marks H3K4me3, H3K27ac and H3K9ac for ChIP-seq. The antibodies received the grades AAA to BBC ( www.ngs-qc.org). We propose to attribute such quantitative grading of all antibodies attributed with the label "ChIP-seq grade".

  17. Detection of Lewis, P1, and some MNS blood group system antibodies by a solid phase assay.

    Science.gov (United States)

    Rolih, S; Thomas, R; Sinor, L

    1995-01-01

    Some solid phase red cell adherence (SPRCA) assays are designed to detect IgG antibodies to red blood cell (RBC) antigens. These assays use anti-IgG-coated red cells as the indicator. It is reported that most antibodies to Lea, Leb, P1, M, and N fail to react by solid phase (SP), presumably because they are IgM antibodies. Those detected are assumed to be IgG. In one year, during routine testing using SPRCA to screen patients for intended RBC transfusion, 28 of 59 such examples were found to react: anti-Lea(9), -Leb(1), -M(14), -N(1), and -P1(3). A study was undertaken to determine if reactivity was due to crosslinking by IgM antibodies of antigen-positive indicator RBCs to antigen-positive reagent RBC monolayers, or due to detection of IgG antibodies. Antibodies were tested according to standard SP protocols, except where IgG-neutralized indicator RBCs were substituted for anti-IgG-active indicator cells. The 59 samples were retested with antigen-positive and antigen-negative indicator RBCs. Only 5 of 59 reacted optimally when antigen-positive indicator cells were used: anti-Lea(2), -Leb(1), -M(1), and -N(1). The reactions of all antibodies were abolished when the anti-IgG component of the indicator was neutralized by soluble IgG. These findings show that detection of most Lewis, P1, M, and N antibodies by SPRCA is dependent on the presence of an IgG antibody in the serum.

  18. Analysis of Liquid Bead Microarray Antibody Assay Data for Epidemiologic Studies of Pathogen-Cancer Associations

    Science.gov (United States)

    Colombara, Danny V.; Hughes, James P.; Burnett-Hartman, Andrea N.; Hawes, Stephen E.; Galloway, Denise A.; Schwartz, Stephen M.; Bostick, Roberd M.; Potter, John D.; Manhart, Lisa E.

    2015-01-01

    Background Liquid bead microarray antibody (LBMA) assays are used to assess pathogen-cancer associations. However, studies analyze LBMA data differently, limiting comparability. Methods We generated 10,000 Monte Carlo-type simulations of log-normal antibody distributions (exposure) with 200 cases and 200 controls (outcome). We estimated type I error rates, statistical power, and bias associated with t-tests, logistic regression with a linear exposure and with the exposure dichotomized at 200 units, 400 units, the mean among controls plus two standard deviations, and the value corresponding to the optimal sensitivity and specificity. We also applied these models, and data visualizations (kernel density plots, receiver operating characteristic (ROC) curves, predicted probability plots, and Q-Q plots), to two empirical datasets to assess the consistency of the exposure-outcome relationship. Results All strategies had acceptable type I error rates (0.03≤P≤0.048), except for the dichotomization according to optimal sensitivity and specificity, which had a type I error rate of 0.27. Among the remaining methods, logistic regression with a linear predictor (Power=1.00) and t-tests (Power=1.00) had the highest power to detect a mean difference of 1.0 MFI (median fluorescence intensity) on the log scale and were unbiased. Dichotomization methods upwardly biased the risk estimates. Conclusion These results indicate that logistic regression with linear predictors and unpaired t-tests are superior to logistic regression with dichotomized predictors for assessing disease associations with LBMA data. Logistic regression with continuous linear predictors and t-tests are preferable to commonly used LBMA dichotomization methods. PMID:26071614

  19. An enzyme-linked immunosorbent assay for the detection of mouse polyomavirus-specific antibodies in laboratory mice.

    NARCIS (Netherlands)

    H.W.J. Broeders; J. Groen (Jan); A.D.M.E. Osterhaus (Albert); G. van Steenis (Bert)

    1994-01-01

    textabstractAn enzyme-linked immunosorbent assay (ELISA) was developed for the detection and quantification of IgM and IgG serum antibodies to mouse polyomavirus (MPV). To evaluate the potential of this ELISA for the screening of laboratory rodents, serum samples from specific pathogen free (SPF) BA

  20. Detection of target staphylococcal enterotoxin B antigen in orange juice and popular carbonated beverages using antibody-dependent antigen-capture assays.

    Science.gov (United States)

    Principato, MaryAnn; Njoroge, Joyce M; Perlloni, Andrei; O' Donnell, Michael; Boyle, Thomas; Jones, Robert L

    2010-10-01

    There is a critical need for qualitative and quantitative methodologies that provide the rapid and accurate detection of food contaminants in complex food matrices. However, the sensitivity of the assay can be affected when antigen-capture is applied to certain foods or beverages that are extremely acidic. This study was undertaken to assess the effects of orange juice and popular carbonated soft drink upon the fidelity of antibody-based antigen-capture assays and to develop simple approaches that could rescue assay performance without the introduction of additional or extensive extraction procedures. We examined the effects of orange juice and a variety of popular carbonated soft drink beverages upon a quantitative Interleukin-2 (IL-2) enzyme-linked immunosorbent assay (ELISA) assay system and a lateral flow device (LFD) adapted for the detection of staphylococcal enterotoxin B (SEB) in foods. Alterations in the performance and sensitivity of the assay were directly attributable to the food matrix, and alterations in pH were especially critical. The results demonstrate that approaches such as an alteration of pH and the use of milk as a blocking agent, either singly or in combination, will partially rescue ELISA performance. The same approaches permit lateral flow to efficiently detect antigen. Practical Application: The authors present ways to rescue an ELISA assay compromised by acidity in beverages and show that either the alteration of pH, or the use of milk as a blocking agent are not always capable of restoring the assay to its intended efficiency. However, the same methods, when employed with lateral flow technology, are rapid and extremely successful.

  1. Production of monoclonal antibodies for detection of Citrus leprosis virus C in enzyme-linked immuno-assays and immunocapture reverse transcription-polymerase chain reaction.

    Science.gov (United States)

    Choudhary, Nandlal; Roy, Avijit; Govindarajulu, A; Nakhla, M K; Levy, L; Brlansky, R H

    2014-09-01

    Citrus leprosis virus C (CiLV-C) causes damage in citrus production in the South and Central America. Since closely related types of citrus viruses have recently been described monoclonal antibodies (MAbs) are needed for accurate and sensitive diagnosis of CiLV-C. In this study, MAbs to the expressed coat protein of CiLV-C were produced for serological detection of CiLV-C in crude extracts of infected tissues in double antibody sandwich enzyme-linked immunosorbent assays (DAS-ELISA), dot blot immunosorbent assays (DBIA) and immuonocapture-reverse transcription-polymerase chain reaction (IC-RT-PCR) procedures. Monoclonal antibodies were developed in mice to the purified expressed coat protein of CiLV-C. The published standard protocols of DAS-ELISA, DBIA and IC-RT-PCR were followed for the detection of coat protein p29 of CiLV-C in the crude extracts of CiLV-C infected tissues. Two monoclonal antibodies, designated G10 and C11, were identified from four potential candidates for the specific and sensitive detection of coat protein p29 of CiLV-C in the crude citrus extracts of CiLV-C infected tissues in DAS-ELISA, whereas G10 was also selected based on performance for use in the DBIA and IC-RT-PCR diagnostic assays. Sensitivity analysis comparing the three methods for detection of coat protein p29 of CiLV-C determined that IC-RT-PCR was more sensitive than DAS-ELISA and DBIA. The creation of MAbs to CiLV-C allows for the sensitive and accurate detection of the virus from CiLV-C infected citrus leaf tissues. Successful detection of the virus in three diagnostic assays formats provides flexibility to diagnosticians who can use either ELISA or DBIA for screening large numbers of samples, and IC-RT-PCR for rapid, sensitive confirmation testing. Published by Elsevier B.V.

  2. Quantitative serology assays for determination of antibody responses to Ebola virus glycoprotein and matrix protein in nonhuman primates and humans.

    Science.gov (United States)

    Vu, Hong; Shulenin, Sergey; Grolla, Allen; Audet, Jonathan; He, Shihua; Kobinger, Gary; Unfer, Robert C; Warfield, Kelly L; Aman, M Javad; Holtsberg, Frederick W

    2016-02-01

    The West Africa Ebola virus disease (EVD) outbreak has reached unprecedented magnitude and caused worldwide concerns for the spread of this deadly virus. Recent findings in nonhuman primates (NHPs) demonstrate that antibodies can be protective against EVD. However, the role of antibody response in vaccine-mediated protection is not fully understood. To address these questions quantitative serology assays are needed for measurement of the antibody response to key Ebola virus (EBOV) proteins. Serology enzyme-linked immunosorbent assays (ELISA's), using a reference detection antibody, were developed in order to standardize the quantitation of antibody levels in vaccinated NHPs or in humans exposed to EBOV or immunized with an EBOV vaccine. Critical reagents were generated to support the development of the serology ELISAs. Recombinant EBOV matrix protein (VP40) was expressed in Escherichia coli and purified. Two variants of the glycoprotein (GP), the ectodomain lacking the transmembrane domain (GPΔTM), and an engineered GP lacking the mucin-like domain (GPΔmuc) were expressed and purified from mammalian cell systems. Using these proteins, three ELISA methods were developed and optimized for reproducibility and robustness, including stability testing of critical reagents. The assay was used to determine the antibody response against VP40, GPΔTM, and GPΔmuc in a NHP vaccine study using EBOV virus-like particles (VLP) vaccine expressing GP, VP40 and the nucleoprotein. Additionally, these ELISAs were used to successfully detect antibody responses to VP40, GPΔTM and GPΔmuc in human sera from EBOV infected individuals.

  3. The effects of affinity-purified anti-DNA antibodies from patients with systemic lupus erythematosus on the fluorescent antinuclear antibody assay using HEp-2 cells.

    Science.gov (United States)

    Suzuki, Kimihiro; Kawamura, Masahide; Mineo, Midori; Shinohara, Tadashi; Kataharada, Koji; Okada, Makoto; Takada, Kunio; Miyawaki, Shoji; Ohsuzu, Fumitaka

    2002-01-01

    The aim of this study was to clarify the effects of anti-dsDNA antibodies on the titer and the nuclear staining pattern(s) in a fluorescent antinuclear antibody (FANA) assay using HEp-2 cells. Anti-dsDNA derived from 14 patients with systemic lupus erythematosus (SLE) was individually affinity-purified. The anti-dsDNA titer of the purified anti-dsDNA solution was measured by radioimmunoassay (RIA) or by enzyme-linked immunosorbent assay (ELISA). In the FANA assay, the anti-dsDNA solution was diluted in a stepwise manner and its titer was expressed by the endpoint dilution. The nuclear staining pattern in the anti-dsDNA solution was examined at the 1:5 and 1:20 dilutions and at the endpoint dilution. The anti-dsDNA titers of the affinity-purified anti-dsDNA solution were high enough (13 to 126 IU/ml) to be measured by RIA. However, the antinuclear antibody (ANA) titers of this solution were relatively low: 1:20 to 1:320. In the study of nuclear staining the peripheral pattern was observed in nine of the 14 cases at a 1:5 dilution. However, at the endpoint dilution, all cases exhibited the homogeneous pattern. These findings indicate that in the FANA assay using HEp-2 cells, 1) although serum samples show high anti-dsDNA titers by RIA or by ELISA, the antibodies' direct contribution to ANA titers is limited, and 2) when samples reveal a homogeneous staining pattern at the endpoint dilution, this suggests the presence of anti-dsDNA.

  4. Automated immunohistochemical assay for estrogen receptor status in breast cancer using monoclonal antibody CC4-5 on the Ventana ES.

    Science.gov (United States)

    Nichols, G E; Frierson, H F; Boyd, J C; Hanigan, M H

    1996-09-01

    Determination of breast cancer estrogen receptor (ER) status as a predictor of tumor response to adjuvant endocrine therapy remains a mainstay of breast cancer management. Recent second generation anti-ER antibodies and new epitope retrieval methods have produced paraffin-based immunohistochemical results that correlate closely with the dextran-coated charcoal (DCC) assay and appear to represent a superior method of ER assay. The authors determined the ER status of 103 invasive breast cancers by paraffin-based, automated immunohistochemistry on the Ventana ES using a new monoclonal antibody, CC4-5, and compared the results to those of parallel DCC biochemical analysis and manual immunohistochemical analysis using anti-ER monoclonal antibody ER1D5. The specificity of the CC4-5 antibody for ER protein was confirmed by Western blot analysis. Sixty of 103 cases were positive for ER by CC4-5 automated immunohistochemistry. With a ligand binding assay threshold value of 20 fmol/mg protein, there were 50 positive cases by biochemical assay. The biochemical results corresponded to an 88% rate of agreement with automated CC4-5 staining. Analysis of discordant cases revealed that the majority of CC4-5 immunopositive only cases (8 of 11) were strongly positive, stroma rich tumors, suggesting that corresponding biochemical measurements were diluted by non representative stromal tissue. There was only one immunonegative, biochemically positive case (27 fmol/mg protein). Semiquantitation of CC4-5 staining using percent positive tumor cells or weighted average staining intensity (HSCORE) showed moderate to good correlation with quantitative DCC results (r = 0.64 and 0.62, P Ventana ES, most likely due to temperature constraints of the instrument. By manual ER1D5 staining, 40 of 79 examined cases were positive corresponding to a 99% rate of agreement with automated CC4-5 staining. Semiquantitation of ER1D5 staining by percent positive tumor cells and weighted average staining

  5. Best practice recommendations for the transfer of cell-based assays for the measurement of neutralizing anti-drug antibodies.

    Science.gov (United States)

    Belouski, Shelley S; Born, Danika; Jacques, Susan; Harder, Brandon; Reynhardt, Kai; Kaliyaperumal, Arunan; Gupta, Shalini

    2016-09-01

    We recommend the application of a strategically designed step-wise approach to transfer cell-based assays that includes assessing analytical performance (through a fit for purpose validation and/or design of experiment robustness characterization), clinical performance (i.e., concordance) and performance or proficiency testing for long-term method monitoring. Here we focus on the application of this strategy to cell-based assays for the measurement of neutralizing anti-drug antibodies. This application is unique in that it requires a custom cell-based assay to be used over a long period of time (potentially phase 1a through the life of a marketed product) with the confidence of consistent method performance and result reporting. But, the process is adaptable to a variety of assay types and applications. We present lessons learned from two cell-based assay transfers that met relevant challenges while implementing alternative permutations of the recommended method transfer process.

  6. A modified enzyme-linked immunosorbent assay for the detection of avian pneumovirus antibodies.

    Science.gov (United States)

    Chiang, S; Dar, A M; Goyal, S M; Sheikh, M A; Pedersen, J C; Panigrahy, B; Senne, D; Halvorson, D A; Nagaraja, K V; Kapur, V

    2000-07-01

    Avian pneumovirus (APV) infection of turkeys in Minnesota was first confirmed in March 1997. Serum samples (n = 5,194) from 539 submissions to Minnesota Veterinary Diagnostic Laboratory were tested by a modified enzyme-linked immunosorbent assay (ELISA). Of these, 2,528 (48.7%) samples from 269 submissions were positive and 2,666 (51.3%) samples from 270 submissions were negative for APV antibodies. Most positive samples were from Kandiyohi, Stearns, Morrison, and Meeker counties in Minnesota. In addition, 10 samples from South Dakota were positive. The sensitivity and specificity of the ELISA test with anti-chicken and anti-turkey conjugates were compared by testing field and experimental sera. The ELISA test with anti-turkey conjugate was more sensitive than that with anti-chicken conjugate. The ELISA tests with antigens prepared with APV strains isolated from Colorado and Minnesota were also compared. No difference was detectable. Currently, the Minnesota Veterinary Diagnostic Laboratory uses an antigen prepared from the Colorado isolate of APV and a goat anti-turkey conjugate in the ELISA test.

  7. Ebolavirus nucleoprotein C-termini potently attract single domain antibodies enabling monoclonal affinity reagent sandwich assay (MARSA formulation.

    Directory of Open Access Journals (Sweden)

    Laura J Sherwood

    Full Text Available BACKGROUND: Antigen detection assays can play an important part in environmental surveillance and diagnostics for emerging threats. We are interested in accelerating assay formulation; targeting the agents themselves to bypass requirements for a priori genome information or surrogates. Previously, using in vitro affinity reagent selection on Marburg virus we rapidly established monoclonal affinity reagent sandwich assay (MARSA where one recombinant antibody clone was both captor and tracer for polyvalent nucleoprotein (NP. Hypothesizing that the closely related Ebolavirus genus may share the same Achilles' heel, we redirected the scheme to see whether similar assays could be delivered and began to explore their mechanism. METHODS AND FINDINGS: In parallel we selected panels of llama single domain antibodies (sdAb from a semi-synthetic library against Zaire, Sudan, Ivory Coast, and Reston Ebola viruses. Each could perform as both captor and tracer in the same antigen sandwich capture assay thereby forming MARSAs. All sdAb were specific for NP and those tested required the C-terminal domain for recognition. Several clones were cross-reactive, indicating epitope conservation across the Ebolavirus genus. Analysis of two immune shark sdAb revealed they also targeted the C-terminal domain, and could be similarly employed, yet were less sensitive than a comparable llama sdAb despite stemming from immune selections. CONCLUSIONS: The C-terminal domain of Ebolavirus NP is a strong attractant for antibodies and enables sensitive sandwich immunoassays to be rapidly generated using a single antibody clone. The polyvalent nature of nucleocapsid borne NP and display of the C-terminal region likely serves as a bountiful affinity sink during selections, and a highly avid target for subsequent immunoassay capture. Combined with the high degree of amino acid conservation through 37 years and across wide geographies, this domain makes an ideal handle for monoclonal

  8. An optimized assay of specific IgE antibodies to reactive dyes and studies of immunologic responses in exposed workers.

    Science.gov (United States)

    Wass, U; Nilsson, R; Nordlinder, R; Belin, L

    1990-03-01

    Methods of assaying reactive dye-specific IgE antibodies were investigated with a RAST. Sera from three patients, occupationally exposed to a reactive dye, Remazol black B (Chemical Abstract registry number 17095-24-8), were used. Directly dyed disks, that is, disks without any carrier protein, resulted in poor and unreliable measures of specific IgE. In contrast, optimized preparation of conjugates between the dye and human serum albumin resulted in efficient binding of specific IgE. The patients' RAST results were strongly positive, whereas sera from 36 exposed workers but without symptoms and sera from unexposed subjects with high levels of total IgE were negative. The hapten and carrier specificity of the IgE antibodies was studied by direct RAST and RAST inhibition. In one patient, the antibodies were principally hapten specific, whereas another patient was found to have antibodies with a high degree of specificity to the carrier. The third patient's antibodies were intermediate between the other two patients' antibodies in this respect, suggesting that antibody specificity is dependent not only on the nature of the hapten but also on individual immune response factors. The study demonstrates that it is important to use an optimized preparation of dye-protein conjugates to elicit reliable results and a high degree of specific IgE binding in the RAST.

  9. Extraction of Ku antigen and anti-Ku antibody assay in various autoimmune connective tissue diseases

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective: To extract Ku antigen and to detect anti-Ku antibody in connective tissue diseases (CTDs). Methods: Ku antigen was prepared from rabbit thymus acetone powder. Anti-Ku antibodies were tested in 50 normal controls and 438 patients

  10. Comparison of Three Enzyme-Linked Immunosorbent Assays for Detection of Immunoglobulin G Antibodies to Tetanus Toxoid with Reference Standards and the Impact on Clinical Practice▿

    Science.gov (United States)

    van Hoeven, Karen H.; Dale, Connie; Foster, Phil; Body, Barbara

    2008-01-01

    Accurate determination of the concentrations of immunoglobulin G (IgG) antibody to tetanus toxoid is important in order to evaluate the immunogenicity of tetanus toxoid vaccines, determine immune competence in individual patients, and measure the prevalence of immunity in populations. The performance of three commercially available enzyme-linked immunosorbent assays (ELISAs) for IgG antibodies to tetanus toxoid were evaluated. Serially diluted NIBSC 76/589 and TE-3 human tetanus IgG immunoglobulin international reference standards were analyzed in quadruplicate using ELISAs manufactured by The Binding Site, Inc. (VaccZyme); Scimedx; and Euroimmun. In addition, IgG antibodies to tetanus toxoid were measured in 83 deidentified serum specimens using each manufacturer's ELISA. Each ELISA provided linear results when evaluated with the reference preparations. The Binding Site ELISA provided results that closely corresponded to the reference preparations (y = 1.09x − 0.08), whereas the Scimedx ELISA gave results that were consistently lower (y = 0.21x − 0.07) and the Euroimmun ELISA gave results that were consistently higher (y = 1.5x + 0.30) than the reference preparation concentrations. Using the recommended cutoff for each ELISA (<0.10 IU/ml), the overall agreement of all of the ELISA methods was 78%. Three of eighty-three (3.6%) human serum samples demonstrated inadequate immunity with all three assays. The Binding Site ELISA yielded nonprotective antibody concentrations in only these 3 samples, whereas 19 samples (22.9%) according to the Scimedx ELISA and 6 samples (7.2%) according to the Euroimmun ELISA demonstrated nonprotective concentrations. The performance characteristics of ELISAs for tetanus immunoglobulin titers were manufacturer dependent, and the differences translated into important disparities in reported results. PMID:18845832

  11. Comparison of three enzyme-linked immunosorbent assays for detection of immunoglobulin g antibodies to tetanus toxoid with reference standards and the impact on clinical practice.

    Science.gov (United States)

    van Hoeven, Karen H; Dale, Connie; Foster, Phil; Body, Barbara

    2008-12-01

    Accurate determination of the concentrations of immunoglobulin G (IgG) antibody to tetanus toxoid is important in order to evaluate the immunogenicity of tetanus toxoid vaccines, determine immune competence in individual patients, and measure the prevalence of immunity in populations. The performance of three commercially available enzyme-linked immunosorbent assays (ELISAs) for IgG antibodies to tetanus toxoid were evaluated. Serially diluted NIBSC 76/589 and TE-3 human tetanus IgG immunoglobulin international reference standards were analyzed in quadruplicate using ELISAs manufactured by The Binding Site, Inc. (VaccZyme); Scimedx; and Euroimmun. In addition, IgG antibodies to tetanus toxoid were measured in 83 deidentified serum specimens using each manufacturer's ELISA. Each ELISA provided linear results when evaluated with the reference preparations. The Binding Site ELISA provided results that closely corresponded to the reference preparations (y=1.09x-0.08), whereas the Scimedx ELISA gave results that were consistently lower (y=0.21x-0.07) and the Euroimmun ELISA gave results that were consistently higher (y=1.5x+0.30) than the reference preparation concentrations. Using the recommended cutoff for each ELISA (<0.10 IU/ml), the overall agreement of all of the ELISA methods was 78%. Three of eighty-three (3.6%) human serum samples demonstrated inadequate immunity with all three assays. The Binding Site ELISA yielded nonprotective antibody concentrations in only these 3 samples, whereas 19 samples (22.9%) according to the Scimedx ELISA and 6 samples (7.2%) according to the Euroimmun ELISA demonstrated nonprotective concentrations. The performance characteristics of ELISAs for tetanus immunoglobulin titers were manufacturer dependent, and the differences translated into important disparities in reported results.

  12. An enzyme-linked immunosorbent assay to detect antibodies against glycoprotein gE of bovine herpesvirus 1 allows differentiation between infected and vaccinated cattle

    NARCIS (Netherlands)

    Oirschot, van J.T.; Kaashoek, M.J.; Maris-Veldhuis, M.A.; Weerdmeester, K.; Rijsewijk, F.A.M.

    1997-01-01

    A blocking enzyme-linked immunosorbent assay (ELISA) was developed for detecting antibodies against glycoprotein gE (gE) of bovine herpesvirus 1 (BHV1). The assay is based on the use of two monoclonal antibodies directed against different antigenic domains on gE. Sera from uninfected cattle and catt

  13. Detection of BRAF mutation in Chinese tumor patients using a highly sensitive antibody immunohistochemistry assay

    Science.gov (United States)

    Qiu, Tian; Lu, Haizhen; Guo, Lei; Huang, Wenting; Ling, Yun; Shan, Ling; Li, Wenbin; Ying, Jianming; Lv, Ning

    2015-03-01

    BRAF mutations can be found in various solid tumors. But accurate and reliable screening for BRAF mutation that is compatible for clinical application is not yet available. In this study, we used an automated immunohistochemistry (IHC) staining coupled with mouse monoclonal anti-BRAF V600E (VE1) primary antibody to screen the BRAF V600E mutation in 779 tumor cases, including 611 colorectal carcinomas (CRC), 127 papillary thyroid carcinomas (PTC) and 41 malignant melanomas. Among the 779 cases, 150 cases were positive for BRAF (V600E) staining, including 38 (of 611, 6%) CRCs, 102 (of 127, 80%) PTCs and 10 (of 41, 24%) malignant melanomas. Sanger sequencing and real-time PCR confirmed the sensitivity and specificity of IHC staining for the V600E mutation are 100% and 99%, respectively. Therefore, our study demonstrates that the fully automated IHC is a reliable tool to determine BRAF mutation status in CRC, PTC and melanoma and can be used for routine clinical screen.

  14. Detection of Francisella tularensis-specific antibodies in patients with tularemia by a novel competitive enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Sharma, Neekun; Hotta, Akitoyo; Yamamoto, Yoshie; Fujita, Osamu; Uda, Akihiko; Morikawa, Shigeru; Yamada, Akio; Tanabayashi, Kiyoshi

    2013-01-01

    A novel competitive enzyme-linked immunosorbent assay (cELISA) was developed and evaluated for detection of antibodies against Francisella tularensis in humans. The assay is based on the ability of serum antibodies to inhibit the binding of monoclonal antibodies (MAbs) directed against F. tularensis lipopolysaccharide antigens. The assay was evaluated using serum samples of tularemia patients, inactivated F. tularensis-immunized rabbits, and F. tularensis-infected mice. Antibodies against F. tularensis were successfully detected in serum samples of tularemia patients as well as the immunized and infected animals. The cELISA method was compared to indirect ELISA (iELISA) and the commonly used microagglutination test (MA) using serum samples of 19 tularemia patients and 50 healthy individuals. The sensitivity and specificity of cELISA were 93.9 and 96.1%, respectively, in comparison to the iELISA. MA was less sensitive than cELISA with a sensitivity and specificity of only 81.8 and 98.0%, respectively. A high degree of correlation (R(2) = 0.8226) was observed between cELISA and iELISA results. The novel cELISA developed in this study appears to be highly sensitive and specific for serodiagnosis of human tularemia. The potential of the MAb-based cELISA to be used in both human and animal samples emphasizes its usefulness for serological survey of tularemia among multiple animal species.

  15. Evaluation of Multiplexed Foot-and-Mouth Disease Nonstructural Protein Antibody Assay Against Standardized Bovine Serum Panel

    Energy Technology Data Exchange (ETDEWEB)

    Perkins, J; Parida, S; Clavijo, A

    2007-05-14

    Liquid array technology has previously been used to show proof-of-principle of a multiplexed non structural protein serological assay to differentiate foot-and-mouth infected and vaccinated animals. The current multiplexed assay consists of synthetically produced peptide signatures 3A, 3B and 3D and recombinant protein signature 3ABC in combination with four controls. To determine diagnostic specificity of each signature in the multiplex, the assay was evaluated against a naive population (n = 104) and a vaccinated population (n = 94). Subsequently, the multiplexed assay was assessed using a panel of bovine sera generated by the World Reference Laboratory for foot-and-mouth disease in Pirbright, UK. This sera panel has been used to assess the performance of other singleplex ELISA-based non-structural protein antibody assays. The 3ABC signature in the multiplexed assay showed comparative performance to a commercially available non-structural protein 3ABC ELISA (Cedi test{reg_sign}) and additional information pertaining to the relative diagnostic sensitivity of each signature in the multiplex is acquired in one experiment. The encouraging results of the evaluation of the multiplexed assay against a panel of diagnostically relevant samples promotes further assay development and optimization to generate an assay for routine use in foot-and-mouth disease surveillance.

  16. Detection of Anaplasma antibodies in wildlife and domestic species in wildlife-livestock interface areas of Kenya by major surface protein 5 competitive inhibition enzyme-linked immunosorbent assay

    Directory of Open Access Journals (Sweden)

    J.J.N. Ngeranwa

    2008-09-01

    Full Text Available The seroprevalence of Anaplasma antibodies in wildlife (eland, blue wildebeest, kongoni, impala, Thomson's gazelle, Grant's gazelle, giraffe and plains zebra and domestic animal (cattle, sheep and goat populations was studied in wildlife / livestock interface areas of Kenya. Serum samples were analyzed by competitive inhibition enzyme-linked immunosorbent assay (CI-ELISA, using a recombinant antigen (MSP-5 from Anaplasma marginale surface membrane. A monoclonal antibody, FC-16, was used as the primary antibody, while anti-mouse conjugated to horseradish peroxidase was used as the secondary antibody. The results indicate a high seroprevalence in both wildlife and livestock populations, in contrast to earlier reports from Kenya, which indicated a low seroprevalence. The differences are attributed to the accurate analytical method used (CI-ELISA, as compared with agglutination techniques, clinical signs and microscopy employed by the earlier workers.

  17. Analysis of antibody responses to Hymenolepis nana infection in mice by the enzyme-linked immunosorbent assay and immunoprecipitation.

    Science.gov (United States)

    Ito, A; Honey, R D; Scanlon, T; Lightowlers, M W; Rickard, M D

    1988-05-01

    Serum antibody responses in two strains of mice infected with embryonated eggs of Hymenolepis nana were analysed by the enzyme-linked immunosorbent assay (ELISA) and immunoprecipitation (IP) using sodium deoxycholate (DOC)-solubilized antigens prepared from embryonated eggs (eggs), mouse-derived cysticercoids (cysts) and adult tapeworms with immature segments only (adults). Highly susceptible dd mice, which harbour mature tapeworms for a long period (greater than 70 days), produced high levels of antibodies to all three different stages of H. nana. BALB/c mice, almost all of which expel adult tapeworms by 30 days after infection, produced high levels of antibody against egg antigens only. The high antibody titres to cyst and adult antigens in dd mice did not lead to expulsion of the worms. However, worms are rejected early in BALB/c mice when there is little or no detectable serum antibody. The antibody responses to eggs seen in BALB/c mice which had long since shed their adult worms were probably due to ingestion of eggs from faeces of other infected mice. Antibodies to eggs were not detected in BALB/c mice which were initially inoculated with eggs (day 0) and then treated with praziquantel on day 6 after the tissue phase of infection only. The different antibody responses to egg antigens and the other two antigens (cyst and adult) in BALB/c mice suggest a difference in antigen specificity between eggs and both cysts and adults. A major antigen component with Mr 32,000 appears to be specific to the egg (or oncosphere) stage of H. nana. Antibody to this major component of eggs was absorbed only with intact eggs, but not with intact cysts nor adults with immature segments only, so that the antigen appears to be on the surface of the oncosphere.

  18. Detection of homocytotropic antibody in lambs infested with the louse, Bovicola ovis, using a basophil histamine-release assay.

    Science.gov (United States)

    Pfeffer, A; Phegan, M D; Bany, J

    1997-07-01

    The utility of a basophil histamine-release assay using washed whole blood cells was examined in lambs and was used to determine if homocytotropic antibody with specificity for Bovicola ovis was produced in response to infestation with the louse. Maximal histamine release in the assay in response to Concanavalin A, anti-ovine IgE monoclonal antibody and, in sensitized lambs, to B. ovis antigen ranged from 18 to 48%. Histamine release from blood cells in response to B. ovis antigen was significantly higher in louse-infested lambs than in louse-naive lambs and was significantly correlated with louse and cockle scores. Passive cutaneous anaphylaxis (PCA) tests were negative with sera obtained from the lambs at the same time as blood for the basophil histamine-release assay. Serum histamine levels also were significantly higher in the louse-infested lambs than in louse-naive lambs and were significantly correlated with louse and cockle scores. The present results support a role for B. ovis-specific homocytotropic antibody in the development of cockle and indicate that the basophil histamine-release assay is more sensitive than the PCA test.

  19. High-throughput pseudovirion-based neutralization assay for analysis of natural and vaccine-induced antibodies against human papillomaviruses.

    Directory of Open Access Journals (Sweden)

    Peter Sehr

    Full Text Available A highly sensitive, automated, purely add-on, high-throughput pseudovirion-based neutralization assay (HT-PBNA with excellent repeatability and run-to-run reproducibility was developed for human papillomavirus types (HPV 16, 18, 31, 45, 52, 58 and bovine papillomavirus type 1. Preparation of 384 well assay plates with serially diluted sera and the actual cell-based assay are separated in time, therefore batches of up to one hundred assay plates can be processed sequentially. A mean coefficient of variation (CV of 13% was obtained for anti-HPV 16 and HPV 18 titers for a standard serum tested in a total of 58 repeats on individual plates in seven independent runs. Natural antibody response was analyzed in 35 sera from patients with HPV 16 DNA positive cervical intraepithelial neoplasia grade 2+ lesions. The new HT-PBNA is based on Gaussia luciferase with increased sensitivity compared to the previously described manual PBNA (manPBNA based on secreted alkaline phosphatase as reporter. Titers obtained with HT-PBNA were generally higher than titers obtained with the manPBNA. A good linear correlation (R(2 = 0.7 was found between HT-PBNA titers and anti-HPV 16 L1 antibody-levels determined by a Luminex bead-based GST-capture assay for these 35 sera and a Kappa-value of 0.72, with only 3 discordant sera in the low titer range. In addition to natural low titer antibody responses the high sensitivity of the HT-PBNA also allows detection of cross-neutralizing antibodies induced by commercial HPV L1-vaccines and experimental L2-vaccines. When analyzing the WHO international standards for HPV 16 and 18 we determined an analytical sensitivity of 0.864 and 1.105 mIU, respectively.

  20. Improved performance of Brucella melitensis native hapten over Brucella abortus OPS tracer on goat antibody detection by the fluorescence polarization assay.

    Science.gov (United States)

    Ramírez-Pfeiffer, C; Díaz-Aparicio, E; Rodríguez-Padilla, C; Morales-Loredo, A; Alvarez-Ojeda, G; Gomez-Flores, R

    2008-06-15

    The current method for goat brucellosis diagnosis is based on the World Organization for Animal Health (OIE) using the screening card test (CT), with antigen at 8% (CT8) or 3% (CT3) of cell concentrations, and the confirmatory complement fixation test (CFT). However, these tests do not differentiate antibodies induced by vaccination from those derived from field infections by Brucella species or other bacterial agents; in places like Mexico, where the prevalence of brucellosis and the vaccination rates are high, there is a considerable percentage of false positive reactions that causes significant unnecessary slaughter of animals. Furthermore, results of the fluorescence polarization assay (FPA) using the Brucella abortus O-polysaccharide (OPS) tracer in goats are poorer than those with cattle. The present study was undertaken to investigate a tracer prepared from the native hapten (NH) of the Rev. 1 strain of Brucella melitensis to improve FPA performance on goat brucellosis diagnosis. Evaluation of 48 positive samples and 96 negative samples showed that the NH tracer was more accurate (pgoat sera samples selected by test series approved by the OIE (card test 3% and CFT). We demonstrated a new application for the NH lipopolysaccharide on detecting antibodies against Brucella using the FPA, which may yield faster results (minutes vs. 24-72h) than the immunodiagnosis assays frequently used in bovine brucellosis. In addition, NH tracer produces similar or better performance results than the conventional OPS tracer, using the FPA in goat sera samples.

  1. Study on the use of an enzyme-linked immunosorbent assay in determining human antibodies to diphtheria toxin as compared with a reference toxin neutralization assay.

    Science.gov (United States)

    Skoura, L; Efstratiou, A; Tsakris, A; Pournaras, S; George, R C; Douboyas, J

    1999-07-01

    Serum samples from 156 Greek persons were assessed by an IgG-specific enzyme-linked immunosorbent assay (ELISA) and a reference tissue culture toxin-neutralization (TN) assay for the quantitation of diphtheria toxin antibodies. By the reference method, 7.7% of the persons were susceptible to diphtheria (antitoxin or = 0.1 IU/ ml), while the corresponding figures were 17.9, 36.5 and 45.5% when they were tested by the immunoassay. None of the samples been susceptible by the TN assay were found to have some protection when tested by ELISA. However, three (6.7%) of the 45 samples showing a basic protection with TN, were fully protective when titrated by the immunoassay. In addition, 31 (31.3%) of the 99 samples been fully protective by the bioassay, were found to be either basically protective or susceptible by means of the ELISA. Overall, validity features of the immunoassay were: sensitivity 68.7%, specificity 94.7%, positive predictive value 95.8% and negative predictive value 63.5%. The ELISA tested in our study could be used to determine diphtheria antitoxin in individuals needed a booster immunization (susceptible or basic protective samples), although it might falsely include in the above categories samples that are within the fully protective levels of antibodies.

  2. The New Aptima HCV Quant Dx Real-time TMA Assay Accurately Quantifies Hepatitis C Virus Genotype 1-6 RNA.

    Science.gov (United States)

    Chevaliez, Stéphane; Dubernet, Fabienne; Dauvillier, Claude; Hézode, Christophe; Pawlotsky, Jean-Michel

    2017-06-01

    Sensitive and accurate hepatitis C virus (HCV) RNA detection and quantification is essential for the management of chronic hepatitis C therapy. Currently available platforms and assays are usually batched and require at least 5hours of work to complete the analyses. The aim of this study was to evaluate the ability of the newly developed Aptima HCV Quant Dx assay that eliminates the need for batch processing and automates all aspects of nucleic acid testing in a single step, to accurately detect and quantify HCV RNA in a large series of patients infected with different HCV genotypes. The limit of detection was estimated to be 2.3 IU/mL. The specificity of the assay was 98.6% (95% confidence interval: 96.1%-99.5%). Intra-assay and inter-assay coefficients of variation ranged from 0.09% to 5.61%, and 1.05% to 3.65%, respectively. The study of serum specimens from patients infected with HCV genotypes 1 to 6 showed a satisfactory relationship between HCV RNA levels measured by the Aptima HCV Quant Dx assay, and both real-time PCR comparators (Abbott RealTime HCV and Cobas AmpliPrep/Cobas TaqMan HCV Test, version 2.0, assays). the new Aptima HCV Quant Dx assay is rapid, sensitive, reasonably specific and reproducible and accurately quantifies HCV RNA in serum samples from patients with chronic HCV infection, including patients on antiviral treatment. The Aptima HCV Quant Dx assay can thus be confidently used to detect and quantify HCV RNA in both clinical trials with new anti-HCV drugs and clinical practice in Europe and the US. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Evaluation by indirect immunofluorescent assay and enzyme linked immunosorbent assay of the dynamic changes of serum antibody responses against severe acute respiratory syndrome coronavirus

    Institute of Scientific and Technical Information of China (English)

    MO Hong-ying; XU Jun; REN Xiao-lan; ZENG Guang-qiao; TAN Ya-xia; CHEN Rong-chang; Moira Chan-Yeung; ZHONG Nan-shan

    2005-01-01

    Background Severe acute respiratory syndrome coronavirus (SARS-CoV) is a newly emerging virus that gives rise to SARS patients with high rates of infectivity and fatality. To study the humoral immune responses to SARS-CoV, the authors evaluated IgG and IgM specific antibodies in patients' sera.Methods Two methods, enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescent assay (IFA), were used to detect specific serum IgG and IgM against SARS-CoV in 98 SARS patients and 250 controls consisting of patients with pneumonia, health-care professionals and healthy subjects. The serum antibody profiles were investigated at different times over one and a half years in 18 of the SARS patients. Results The sensitivity and specificity of ELISA for detecting IgG against SARS-CoV were 100.0% and 97.2% and for IgM 89.8% and 97.6% respectively; the figures using IFA for IgG were 100.0% and 100.0% and for IgM 81.8% and 100.0% respectively. During the first seven days of the antibodies trace test, no IgG and IgM were detected, but on day 15, IgG response increased dramatically, reaching a peak on day 60, remaining high up to day 180 and decreasing gradually until day 540. On day 15, IgM was detected, rapidly reached a peak, then declined gradually until day 180 when IgM was undetectable. Conclusion The detection of antibodies against SARS virus is helpful in the clinical diagnosis of SARS.

  4. Detection of antibodies to Campylobacter in humans using enzyme-linked immunosorbent assays: a review of the literature.

    Science.gov (United States)

    Kuhn, Katrin Gaardbo; Falkenhorst, Gerhard; Ceper, Tina; Dalby, Tine; Ethelberg, Steen; Mølbak, Kåre; Krogfelt, Karen A

    2012-10-01

    Campylobacteriosis is the most common cause of bacterial foodborne illness in the European Union and the United States. Infection with Campylobacter spp. is frequently associated with different sequelae including neuropathies and reactive arthritis. Diagnosis is mainly by bacterial culturing which is time consuming, expensive, and not well suited for diagnosing sequelae or identifying infections from stool samples with nonviable bacteria. Serologic assays, in particular ELISAs, are well suited for this purpose, but, at present, there is no international consensus on antibody assays for human campylobacteriosis. In an extensive literature review, 19 studies validating such assays were identified of which 13 were more than 10 years old. We conclude that the best validated of these assays are developed and used in-house for research purposes rather than for routine diagnostics. Considering the burden of disease and potential long-term severity of Campylobacter infections, developing a standardized, commercially available antibody assay could be of great benefit for diagnostic and surveillance purposes worldwide. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Quality control and evaluation of human immunodeficiency virus antibody assays used for screening donated blood in China

    Institute of Scientific and Technical Information of China (English)

    YOU CHUN WANG; XIU HUA LI; AI JING SONG; CHUN TAO ZHANG; SI HONG XU; FENG ZHANG; HONG ZHANG YIN

    2006-01-01

    During 2004, a total of 124 batches of HIV antibody ELISAs from domestic and overseas manufacturers, comprising approximately 60 million tests, were tested for quality and released for screening blood in China. The inter- and intra-batch variation, specificity, and sensitivity were evaluated using a laboratory panel and clinical samples. The inter-batch variation was less than 15% and only 2 of 12 assays had intra-batch variation of less than 20% for 4 dilutions of a control specimen.257 samples confirmed positive for HIV antibody and 4826 negative samples from different regions in China were used to evaluate the sensitivity and specificity of the assays. The results showed that the sensitivity is in the range from 93.7% to 100% for assays sampled directly from the manufacturers,and 91.4%-99.6% for those retrieved from the consumers; the specificity was in the range from 97.88% to 99.97%. The testing environment may vary in different regions of China. Therefore, manufacturers should provide robust assays to satisfy the requirements of these diverse environments, and especially reduce the intra-assay variation and improve the stability of the kits.

  6. Modular, Antibody-free Time-Resolved LRET Kinase Assay Enabled by Quantum Dots and Tb3+-sensitizing Peptides

    Science.gov (United States)

    Cui, Wei; Parker, Laurie L.

    2016-07-01

    Fluorescent drug screening assays are essential for tyrosine kinase inhibitor discovery. Here we demonstrate a flexible, antibody-free TR-LRET kinase assay strategy that is enabled by the combination of streptavidin-coated quantum dot (QD) acceptors and biotinylated, Tb3+ sensitizing peptide donors. By exploiting the spectral features of Tb3+ and QD, and the high binding affinity of the streptavidin-biotin interaction, we achieved multiplexed detection of kinase activity in a modular fashion without requiring additional covalent labeling of each peptide substrate. This strategy is compatible with high-throughput screening, and should be adaptable to the rapidly changing workflows and targets involved in kinase inhibitor discovery.

  7. EL4 cell-based colorimetric toxin neutralization activity assays for determination of neutralizing anti-ricin antibodies.

    Science.gov (United States)

    Lindsey, Changhong Y; Brown, J Edward; Torabazar, Nahid R; Smith, Leonard A

    2013-01-01

    A recombinant ricin toxin A-chain 1-33/44-198 vaccine (RVEc), developed at the United States Army Medical Research Institute of Infectious Diseases as a vaccine candidate, is under investigation in a phase 1 clinical study. To effectively evaluate the immunogenicity of this ricin vaccine and to eliminate the use of radioactive material, an EL4 cell-based colorimetric toxin neutralization activity (TNA) assay using a CellTiter 96 AQueous One Solution Cell Proliferation Assay Reagent has been developed, optimized, and applied in the vaccine efficacy studies. The TNA assay measures the protective neutralizing anti-ricin antibodies in animal sera by determining the cell viability after ricin exposure in the assay system and comparing it to a purified mouse polyclonal antiricin IgG standard curve. The standard curve of the anti-ricin TNA assay closely fits a four-parameter logistic regression model. The unknown test sample concentration was expressed as microg/mL, but not the 50% effective concentration (EC50), which was determined by most TNA assays. The neutralizing endpoint titers, not the 50% effective dilution (ED50), of human specimens were measured with the TNA assay in support of the clinical study of the RVEc vaccine. The optimal amount of ricin toxin, EL4 cells, and concentration of standards used in the assay system was established to minimize false-negative and false-positive results of serum specimens from the nonclinical and clinical studies of RVEc. The testing conditions were adjusted to optimize assay performance. The colorimetric TNA assay replaced a radioactive TNA assay previously used in the ricin vaccine studies.

  8. Peptide-based protein capture agents with high affinity, selectivity, and stability as antibody replacements in biodetection assays

    Science.gov (United States)

    Coppock, Matthew B.; Farrow, Blake; Warner, Candice; Finch, Amethist S.; Lai, Bert; Sarkes, Deborah A.; Heath, James R.; Stratis-Cullum, Dimitra

    2014-05-01

    Current biodetection assays that employ monoclonal antibodies as primary capture agents exhibit limited fieldability, shelf life, and performance due to batch-to-batch production variability and restricted thermal stability. In order to improve upon the detection of biological threats in fieldable assays and systems for the Army, we are investigating protein catalyzed capture (PCC) agents as drop-in replacements for the existing antibody technology through iterative in situ click chemistry. The PCC agent oligopeptides are developed against known protein epitopes and can be mass produced using robotic methods. In this work, a PCC agent under development will be discussed. The performance, including affinity, selectivity, and stability of the capture agent technology, is analyzed by immunoprecipitation, western blotting, and ELISA experiments. The oligopeptide demonstrates superb selectivity coupled with high affinity through multi-ligand design, and improved thermal, chemical, and biochemical stability due to non-natural amino acid PCC agent design.

  9. A rapid, accurate and robust particle-based assay for the simultaneous screening of plasma samples for the presence of five different anti-cytokine autoantibodies

    DEFF Research Database (Denmark)

    Guldager, Daniel Kring Rasmussen; von Stemann, Jakob Hjorth; Larsen, Rune

    2015-01-01

    PURPOSE: To establish and validate a rapid, cost-effective and accurate screening assay for the simultaneous testing of human naturally occurring anti-cytokine autoantibodies (c-aAb) targeting interleukin-1α (IL-1α), interleukin-6 (IL-6), interleukin-10 (IL-10), granulocyte-macrophage colony...... plasma samples and pooled normal immunoglobulin preparations were used to validate the assay. Plasma samples from 98 transfusion recipients, half of whom presented with febrile reactions, were tested by the assay. RESULTS: The assay detected specific and saturable immunoglobulin G (IgG) binding to each...... cytokine autoantibodies quantities in the negative plasma samples ranged between 80% and 125%. The analytical intra- and inter-assay variations were 4% and 11%, respectively. Varying c-aAb levels were detectable in the transfusion recipients. There was no difference in c-aAb frequency between the patients...

  10. An enzyme-linked immunosorbent assay for detection of avian influenza virus subtypes H5 and H7 antibodies

    OpenAIRE

    Jensen, Trine Hammer; Ajjouri, Gitte; Handberg, Kurt; Slomka, Marek J.; Coward, Vivien J; Cherbonnel, Martine; Jestin, Véronique; Lind, Peter; Jørgensen, Poul Henrik

    2013-01-01

    BACKGROUND: Avian influenza virus (AIV) subtypes H5 and H7 attracts particular attention because of the risk of their potential pathogenicity in poultry. The haemagglutination inhibition (HI) test is widely used as subtype specific test for serological diagnostics despite the laborious nature of this method. However, enzyme-linked immunosorbent assays (ELISAs) are being explored as an alternative test method.H5 and H7 specific monoclonal antibodies were experimentally raised and used in the d...

  11. Recombinant nucleocapsid protein-based enzyme-linked immunosorbent assay for detection of antibody to turkey coronavirus.

    Science.gov (United States)

    Abdelwahab, Mohamed; Loa, Chien Chang; Wu, Ching Ching; Lin, Tsang Long

    2015-06-01

    Nucleocapsid (N) protein gene of turkey coronavirus (TCoV) was expressed in a prokaryotic system and used to develop an enzyme-linked immunosorbent assay (ELISA) for detection of antibody to TCoV. Anti-TCoV hyperimmune turkey serum and normal turkey serum were used as positive or negative controls for optimization of the ELISA. Goat anti-turkey IgG (H+L) conjugated with horseradish peroxidase was used as detector antibody. Three hundred and twenty two turkey sera from the field were used to evaluate the performance of ELISA and determine the cut-off point of ELISA. The established ELISA was also examined with serum samples obtained from turkeys experimentally infected with TCoV. Those serum samples were collected at various time intervals from 1 to 63 days post-infection. The optimum conditions for differentiation between anti-TCoV hyperimmune serum and normal turkey serum were recombinant TCoV N protein concentration at 20 μg/ml, serum dilution at 1:800, and conjugate dilution at 1:10,000. Of the 322 sera from the field, 101 were positive for TCoV by immunofluorescent antibody assay (IFA). The sensitivity and specificity of the ELISA relative to IFA test were 86.0% and 96.8%, respectively, using the optimum cut-off point of 0.2 as determined by logistic regression method. Reactivity of anti-rotavirus, anti-reovirus, anti-adenovirus, or anti-enterovirus antibodies with the recombinant N protein coated on the ELISA plates was not detected. These results indicated that the established antibody-capture ELISA in conjunction with recombinant TCoV N protein as the coating protein can be utilized for detection of antibodies to TCoV in turkey flocks.

  12. Minimizing antibody cross-reactivity in multiplex detection of biomarkers in paper-based point-of-care assays

    Science.gov (United States)

    Dias, J. T.; Lama, L.; Gantelius, J.; Andersson-Svahn, H.

    2016-04-01

    Highly multiplexed immunoassays could allow convenient screening of hundreds or thousands of protein biomarkers simultaneously in a clinical sample such as serum or plasma, potentially allowing improved diagnostic accuracy and clinical management of many conditions such as autoimmune disorders, infections, and several cancers. Currently, antibody microarray-based tests are limited in part due to cross reactivity from detection antibody reagents. Here we present a strategy that reduces the cross-reactivity between nanoparticle-bound reporter antibodies through the application of ultrasound energy. By this concept, it was possible to achieve a sensitivity 103-fold (5 pg mL-1) lower than when no ultrasound was applied (50 ng mL-1) for the simultaneous detection of three different antigens. The detection limits and variability achieved with this technique rival those obtained with other types of multiplex sandwich assays.Highly multiplexed immunoassays could allow convenient screening of hundreds or thousands of protein biomarkers simultaneously in a clinical sample such as serum or plasma, potentially allowing improved diagnostic accuracy and clinical management of many conditions such as autoimmune disorders, infections, and several cancers. Currently, antibody microarray-based tests are limited in part due to cross reactivity from detection antibody reagents. Here we present a strategy that reduces the cross-reactivity between nanoparticle-bound reporter antibodies through the application of ultrasound energy. By this concept, it was possible to achieve a sensitivity 103-fold (5 pg mL-1) lower than when no ultrasound was applied (50 ng mL-1) for the simultaneous detection of three different antigens. The detection limits and variability achieved with this technique rival those obtained with other types of multiplex sandwich assays. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr09207h

  13. Relation between enzyme-linked immunosorbent assay and radioimmunoassay for detection of antibodies to the capsular polysaccharide of Haemophilus influenzae type b

    Energy Technology Data Exchange (ETDEWEB)

    Kristensen, K. (Streptococcus Department, Statens Seruminstitut, Copenhagen (Denmark)); Weis Bentzon, M. (Department of Biostatistics, Statens Seruminstitut, Copenhagen (Denmark))

    1992-01-01

    The measurement of antibodies to the capsular polysaccharide (PRP) of Haemophilus influenzae type b (Hib) is important because vaccines inducing such antibodies are now available. We developed and evaluated an enzyme-linked immunosorbent assay (ELISA) for detection of these antibodies based on direct coating of the plates with tyraminated PRP. The assay fulfilled the requirements for parallel line assays; it was sensitive, specific, and reproducible with a coefficient of variation between days of 19%. Results from the ELISA were compared with results from radioimmunoassay and a correlation coefficient of 0.93 was found. Results obtained by the two methods were proportional and the relation was indepenedent of the antibody level. The relation between them was also unaffected by the contribution of different antibody isotypes, indicating that these were measured to the same extent by both methods. ELISA employing direct coating of the plates with tyraminated PRP represents a useful alternative for detection of antibodies when studying immunogenicity of Hib vaccines. (au).

  14. Development of monoclonal antibodies and quantitative sandwich enzyme linked immunosorbent assay for the characteristic sialoglycoprotein of edible bird's nest.

    Science.gov (United States)

    Zhang, Shiwei; Lai, Xintian; Liu, Xiaoqing; Li, Yun; Li, Bifang; Huang, Xiuli; Zhang, Qinlei; Chen, Wei; Lin, Lin; Yang, Guowu

    2013-01-01

    The article presents a sandwich enzyme linked immunosorbent assay (ELISA) for identification of edible bird's nest. The characteristic sialoglycoproteins were found by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and purified by liquid-phase isoelectric focusing (LIEF). According to the analysis, the molecular weight was 106-128 kDa and the isoelectric point was ≤pH 3.0. Two anti-characteristic sialoglycoprotein monoclonal antibodies were produced. The monoclonal antibodies were examined by western-blot assay. One of the monoclonal antibody was used as coating and the other as the enzyme-labeled antibody after being coupled to horseradish peroxidase (HRP). Based on the optimized ELISA condition, the method was established with IC(50) of 1.5 ng/mL, and low cross-reactivity with various fake materials (ELISA provided a suitable means for screening of a large number of samples. The coefficients of variation were between 2.9% and 5.8%.

  15. Anti-glomerular basement membrane antibodies in the diagnosis of Goodpasture syndrome: a comparison of different assays.

    Science.gov (United States)

    Sinico, Renato Alberto; Radice, Antonella; Corace, Caterina; Sabadini, Ettore; Bollini, Bruna

    2006-02-01

    The role of anti-glomerular basement membrane (GBM) antibodies in the pathogenesis of Goodpasture syndrome (GPS) is firmly established. Untreated, the disease may follow a fulminating course. Early identification of patients has important implications in terms of management and prognosis. Therefore, a diagnostic test for the determination of circulating anti-GBM antibodies, of very high sensitivity and specificity, is necessary. A number of assays, using different antigenic substrates, are available, but studies comparing the 'performances' of the different tests are scarce. The aim of our work was to evaluate the sensitivity and specificity of four immunoassay-based anti-GBM antibodies kits. Thirty-four serum samples from 19 GPS patients, 41 pathological and 28 normal controls were studied retrospectively (the follow-up samples were not included in the analysis of performance data). Cut-off limits were derived from receiver operating characteristics curve analysis. All the assays showed a comparable good sensitivity (between 94.7 and 100.0%), whereas specificity varied considerably (from 90.9 to 100.0%). The better performance in terms of sensitivity/specificity was achieved by a fluorescence immunoassay which utilizes a recombinant antigen. All the assays have a good performance, with high sensitivity; however, the specificity may vary considerably.

  16. The New Aptima HBV Quant Real-Time TMA Assay Accurately Quantifies Hepatitis B Virus DNA from Genotypes A to F.

    Science.gov (United States)

    Chevaliez, Stéphane; Dauvillier, Claude; Dubernet, Fabienne; Poveda, Jean-Dominique; Laperche, Syria; Hézode, Christophe; Pawlotsky, Jean-Michel

    2017-04-01

    Sensitive and accurate hepatitis B virus (HBV) DNA detection and quantification are essential to diagnose HBV infection, establish the prognosis of HBV-related liver disease, and guide the decision to treat and monitor the virological response to antiviral treatment and the emergence of resistance. Currently available HBV DNA platforms and assays are generally designed for batching multiple specimens within an individual run and require at least one full day of work to complete the analyses. The aim of this study was to evaluate the ability of the newly developed, fully automated, one-step Aptima HBV Quant assay to accurately detect and quantify HBV DNA in a large series of patients infected with different HBV genotypes. The limit of detection of the assay was estimated to be 4.5 IU/ml. The specificity of the assay was 100%. Intra-assay and interassay coefficients of variation ranged from 0.29% to 5.07% and 4.90% to 6.85%, respectively. HBV DNA levels from patients infected with HBV genotypes A to F measured with the Aptima HBV Quant assay strongly correlated with those measured by two commercial real-time PCR comparators (Cobas AmpliPrep/Cobas TaqMan HBV test, version 2.0, and Abbott RealTime HBV test). In conclusion, the Aptima HBV Quant assay is sensitive, specific, and reproducible and accurately quantifies HBV DNA in plasma samples from patients with chronic HBV infections of all genotypes, including patients on antiviral treatment with nucleoside or nucleotide analogues. The Aptima HBV Quant assay can thus confidently be used to detect and quantify HBV DNA in both clinical trials with new anti-HBV drugs and clinical practice. Copyright © 2017 American Society for Microbiology.

  17. A Novel IgM-capture enzyme-linked immunosorbent assay using recombinant Vag8 fusion protein for the accurate and early diagnosis of Bordetella pertussis infection.

    Science.gov (United States)

    Otsuka, Nao; Gotoh, Kensei; Nishimura, Naoko; Ozaki, Takao; Nakamura, Yukitsugu; Haga, Kiyohito; Yamazaki, Makoto; Gondaira, Fumio; Okada, Kenji; Miyaji, Yusuke; Toyoizumi-Ajisaka, Hiromi; Shibayama, Keigo; Arakawa, Yoshichika; Kamachi, Kazunari

    2016-05-01

    An ELISA that measures anti-PT IgG antibody has been used widely for the serodiagnosis of pertussis; however, the IgG-based ELISA is inadequate for patients during the acute phase of the disease because of the slow response of anti-PT IgG antibodies. To solve this problem, we developed a novel IgM-capture ELISA that measures serum anti-Bordetella pertussis Vag8 IgM levels for the accurate and early diagnosis of pertussis. First, we confirmed that Vag8 was highly expressed in all B. pertussis isolates tested (n = 30), but little or none in other Bordetella species, and that DTaP vaccines did not induce anti-Vag8 IgG antibodies in mice (i.e. the antibody level could be unaffected by the vaccination). To determine the immune response to Vag8 in B. pertussis infection, anti-Vag8 IgM levels were compared between 38 patients (acute phase of pertussis) and 29 healthy individuals using the anti-Vag8 IgM-capture ELISA. The results revealed that the anti-Vag8 IgM levels were significantly higher in the patients compared with the healthy individuals (P < 0.001). ROC analysis also showed that the anti-Vag8 IgM-capture ELISA has higher diagnostic accuracy (AUC, 0.92) than a commercial anti-PT IgG ELISA kit. Moreover, it was shown that anti-Vag8 IgM antibodies were induced earlier than anti-PT IgG antibodies on sequential patients' sera. These data indicate that our novel anti-Vag8 IgM-capture ELISA is a potentially useful tool for making the accurate and early diagnosis of B. pertussis infection.

  18. Auto-antibodies to double-stranded DNA as biomarker in systemic lupus erythematosus : comparison of different assays during quiescent and active disease

    NARCIS (Netherlands)

    de Leeuw, Karina; Bungener, Laura; Roozendaal, Caroline; Bootsma, Hendrika; Stegeman, Coen A

    2017-01-01

    OBJECTIVE: Auto-antibodies directed to dsDNA (anti-dsDNA) are used in diagnosis and follow-up for SLE. However, multiple assays are used. The objective of this study was to determine the best-performing assays, especially in prediction of exacerbations. METHODS: Seven assays were compared during LN

  19. Antibody

    Science.gov (United States)

    An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples ... microorganisms (bacteria, fungi, parasites, and viruses) and chemicals. Antibodies may be produced when the immune system mistakenly ...

  20. A monoclonal antibody-based VZV glycoprotein E quantitative assay and its application on antigen quantitation in VZV vaccine.

    Science.gov (United States)

    Liu, Jian; Zhu, Rui; Ye, Xiangzhong; Yang, Lianwei; Wang, Yongmei; Huang, Yanying; Wu, Jun; Wang, Wei; Ye, Jianghui; Li, Yimin; Zhao, Qinjian; Zhu, Hua; Cheng, Tong; Xia, Ningshao

    2015-06-01

    Varicella-zoster virus (VZV) is a highly infectious agent that causes varicella and herpes zoster (HZ), which may be associated with severe neuralgia. Vaccination is the most effective way to reduce the burden of the diseases. VZV glycoprotein E (gE) is the major and most immunogenic membrane protein that plays important roles in vaccine efficacy. A quantitative assay for gE content is desirable for the VZV vaccine process monitoring and product analysis. In this study, 70 monoclonal antibodies (mAbs) were obtained after immunizing mice with purified recombinant gE (rgE). The collection of mAbs was well-characterized, and a pair of high-affinity neutralization antibodies (capture mAb 4A2 and detection mAb 4H10) was selected to establish a specific and sensitive sandwich enzyme-linked immunosorbent assay (ELISA) to quantify the native and recombinant gE. The detection limit of this assay was found to be 1.95 ng/mL. Furthermore, a reasonably good correlation between the gE content (as measured by the mAb-based quantitative ELISA) and the virus titer (as measured by the "gold standard" plaque assay) was observed when both assays were performed for tracking the kinetics of virus growth during cell culture. A total of 16 batches of lyophilized VZV vaccine were tested using the newly developed quantitative ELISA and classical plaque assay, demonstrating reasonably good correlation between gE content and virus titer. Therefore, this mAb-based gE quantitative assay serves as a rapid, stable, and sensitive method for monitoring viral antigen content, one additional quantitative method for VZV vaccine process and product characterization. This quantitative ELISA may also serve as a complementary method for virus titering.

  1. A pseudovirus-based hemagglutination-inhibition assay as a rapid, highly sensitive, and specific assay for detecting avian influenza A (H7N9 antibodies

    Directory of Open Access Journals (Sweden)

    Anli Zhang

    2015-06-01

    Full Text Available Background Increased surveillance of avian-origin influenza A (H7N9 virus infection is critical to assess the risk of new outbreaks in China. A high-throughput assay with a good safety profile, sensitivity, and specificity is urgently needed. Methods We used a hemagglutination-inhibition (HI assay based on an H7N9-enveloped pseudovirus to assess serum neutralization antibodies level in 40 H7N9 positive sera and 40 H7N9 negative sera and compared the efficacy of the assay with traditional HI test and micro-neutralization (MN test. Results Spearman’s rank correlation coefficient analysis showed pseudovirus HI (PHI titers correlated well with both HI titers and MN titers. Receiver operating characteristic (ROC curves test revealed using a PHI cut-off titer of 10, the sensitivity and specificity reached 1.0. Conclusions PHI can be used in H7N9-related serological studies. This assay is high-throughput, very sensitive and specific, and cost effective.

  2. Heterogeneous Antibody-Based Activity Assay for Lysine Specific Demethylase 1 (LSD1) on a Histone Peptide Substrate.

    Science.gov (United States)

    Schmitt, Martin L; Ladwein, Kathrin I; Carlino, Luca; Schulz-Fincke, Johannes; Willmann, Dominica; Metzger, Eric; Schilcher, Pierre; Imhof, Axel; Schüle, Roland; Sippl, Wolfgang; Jung, Manfred

    2014-07-01

    Posttranslational modifications of histone tails are very important for epigenetic gene regulation. The lysine-specific demethylase LSD1 (KDM1A/AOF2) demethylates in vitro predominantly mono- and dimethylated lysine 4 on histone 3 (H3K4) and is a promising target for drug discovery. We report a heterogeneous antibody-based assay, using dissociation-enhanced lanthanide fluorescent immunoassay (DELFIA) for the detection of LSD1 activity. We used a biotinylated histone 3 peptide (amino acids 1-21) with monomethylated lysine 4 (H3K4me) as the substrate for the detection of LSD1 activity with antibody-mediated quantitation of the demethylated product. We have successfully used the assay to measure the potency of reference inhibitors. The advantage of the heterogeneous format is shown with cumarin-based LSD1 inhibitor candidates that we have identified using virtual screening. They had shown good potency in an established LSD1 screening assay. The new heterogeneous assay identified them as false positives, which was verified using mass spectrometry.

  3. Direct replacement of antibodies with molecularly imprinted polymer nanoparticles in ELISA--development of a novel assay for vancomycin.

    Science.gov (United States)

    Chianella, Iva; Guerreiro, Antonio; Moczko, Ewa; Caygill, J Sarah; Piletska, Elena V; De Vargas Sansalvador, Isabel M Perez; Whitcombe, Michael J; Piletsky, Sergey A

    2013-09-03

    A simple and straightforward technique for coating microplate wells with molecularly imprinted polymer nanoparticles (nanoMIPs) to develop assays similar to the enzyme-linked immunosorbent assay (ELISA) is presented here for the first time. NanoMIPs were synthesized by a solid-phase approach with an immobilized vancomycin (template) and characterized using Biacore 3000, dynamic light scattering, and electron microscopy. Immobilization, blocking, and washing conditions were optimized in microplate format. The detection of vancomycin was achieved in competitive binding experiments with a horseradish peroxidase-vancomycin conjugate. The assay was capable of measuring vancomycin in buffer and in blood plasma within the range of 0.001-70 nM with a detection limit of 0.0025 nM (2.5 pM). The sensitivity of the assay was 3 orders of magnitude better than a previously described ELISA based on antibodies. In these experiments, nanoMIPs have shown high affinity and minimal interference from blood plasma components. Immobilized nanoMIPs were stored for 1 month at room temperature without any detrimental effects to their binding properties. The high affinity of nanoMIPs and the lack of a requirement for cold chain logistics make them an attractive alternative to traditional antibodies used in ELISA.

  4. Gold Nanostar Enhanced Surface Plasmon Resonance Detection of an Antibiotic at Attomolar Concentrations via an Aptamer-Antibody Sandwich Assay.

    Science.gov (United States)

    Kim, Suhee; Lee, Hye Jin

    2017-06-20

    A new sandwich assay for tetracycline (TC) involving a DNA aptamer and antibody pair is demonstrated in conjunction with gold nanostar (GNS) enhanced surface plasmon resonance (SPR) to achieve detection in the low attomolar range. GNS particles were covalently functionalized with the antibody probe (antiTC) and integrated into a surface sandwich assay in conjunction with a SPR gold chip modified with the TC-specific aptamer. After it was demonstrated that both affinity probes can bind simultaneously to TC, optimization of the assay was performed using either antiTC only or GNS-antiTC conjugates to interact with aptamer/TC complexes present on the chip surface. Target concentrations as low as 10 aM could be detected using GNS-antiTC's, which was >10(3) times greater in performance than when using antiTC only. In addition, good selectivity was achieved with respect to other tetracycline derivative antibiotics, such as oxytetracycline (OTC) and chlortetracycline (CTC), both which are structurally similar to TC. As a demonstration of trace antibiotic analysis in environmental samples, the GNS enhanced sandwich assay was applied to analyze TC added to aliquots of local river water and the results validated by comparing to conventional high-performance liquid chromatography (HPLC) analysis.

  5. Profiling of multiple signal pathway activities by multiplexing antibody and GFP-based translocation assays.

    Science.gov (United States)

    Henriksen, Ulla; Fog, Jacob; Loechel, Frosty; Praestegaard, Morten

    2008-08-01

    Multiplexing of GFP based and immunofluorescence translocation assays enables easy acquisition of multiple readouts from the same cell in a single assay run. Immunofluorescence assays monitor translocation, phosphorylation, and up/down regulation of endogenous proteins. GFP-based assays monitor translocation of stably expressed GFP-fusion proteins. Such assays may be multiplexed along (vertical), across (horizontal), and between (branch) signal pathways. Examples of these strategies are presented: 1) The MK2-GFP assay monitors translocation of MK2-GFP from the nucleus to the cytoplasm in response to stimulation of the p38 pathway. By applying different immunofluorescent assays to the MK2 assay, a multiplexed HCA system is created for deconvolution of p38 pathway activation including assay readouts for MK2, p38, NFkappaB, and c-Jun. 2) A method for evaluating GPCR activation and internalization in a single assay run has been established by multiplexing GFP-based internalization assays with immunofluorescence assays for downstream transducers of GPCR activity: pCREB (cAMP sensor), NFATc1 (Ca(2+) sensor), and ERK (G-protein activation). Activation of the AT1 receptor is given as an example. 3) Cell toxicity readouts can be linked to primary readouts of interest via acquisition of secondary parameters describing cellular morphology. This approach is used to flag cytotoxic compounds and deselect false positives. The ATF6 Redistribution assay is provided as an example. These multiplex strategies provide a unique opportunity to enhance HCA data quality and save time during drug discovery. From a single assay run, several assay readouts are obtained that help the user to deconvolute the mode of action of test compounds.

  6. Kesesuaian Hasil Pemeriksaan Antibodi Virus Herpes Simpleks Metode Enzyme-Linked Immunofiltration Assay dengan Enzyme-Linked Immunosorbent Assay

    Directory of Open Access Journals (Sweden)

    Victor Immanuel

    2012-09-01

    Full Text Available Herpes simplex virus (HSV infections are very common and are caused by HSV type 1 (HSV-1 and HSV type 2 (HSV-2. HSV-1 being mostly associated with orofacial disease, whereas HSV-2 is usually associated with perigenital infection. Diagnosis of HSV infection is established based on history, physical and laboratory examination. Enzyme-linked immunosorbent assay (ELISA method to detect anti-HSV has a sensitivity 93–100% and specificity 95–100%, whereas enzyme-linked immunofiltration assay (ELIFA has a sensitivity 83.36–97% and specificity 83.93–98%. The aim of this study was to assess the agreement of anti-HSV between ELIFA and ELISA methods. This study was conducted in the clinical laboratory RSUP Dr. Hasan Sadikin Bandung since January to May 2011. The study design was cross sectional. Subjects of this study were serum of patients suspected HSV infection. Statistical analysis was performed to assess Kappa agreement. A total of 66 samples were examined anti-HSV using ELIFA and ELISA method. There was good agreement between test results of anti-HSV IgM ELIFA and ELISA method (p<0.001, κ=0.621, moderate agreement between test results of anti- HSV-1 IgG ELIFA and ELISA method (p<0.001, κ=0.533, and fair agreement between test results of anti-HSV-2 IgG ELIFA and ELISA method (p=0.006, κ= 0.260. In conclusions, only the anti-HSV IgM ELIFA method has good agreement with ELISA.

  7. Sensitive and specific enzyme-linked immunosorbent assay for detecting serum antibodies against Mycobacterium avium subsp. paratuberculosis in fallow deer.

    Science.gov (United States)

    Prieto, José M; Balseiro, Ana; Casais, Rosa; Abendaño, Naiara; Fitzgerald, Liam E; Garrido, Joseba M; Juste, Ramon A; Alonso-Hearn, Marta

    2014-08-01

    The enzyme-linked immunosorbent assay (ELISA) is the diagnostic test most commonly used in efforts to control paratuberculosis in domestic ruminants. However, commercial ELISAs have not been validated for detecting antibodies against Mycobacterium avium subsp. paratuberculosis in wild animals. In this study, we compared the sensitivities and specificities of five ELISAs using individual serum samples collected from 41 fallow deer with or without histopathological lesions consistent with paratuberculosis. Two target antigenic preparations were selected, an ethanol-treated protoplasmic preparation obtained from a fallow deer M. avium subsp. paratuberculosis isolate (ELISAs A and B) and a paratuberculosis protoplasmic antigen (PPA3) (ELISAs C and D). Fallow deer antibodies bound to the immobilized antigens were detected by using a horseradish peroxidase (HRP)-conjugated anti-fallow deer IgG antibody (ELISAs A and C) or HRP-conjugated protein G (ELISAs B and D). A commercially available assay, ELISA-E, which was designed to detect M. avium subsp. paratuberculosis antibodies in cattle, sheep, and goats, was also tested. Although ELISAs A, C, and E had the same sensitivity (72%), ELISAs A and C were more specific (100%) for detecting fallow deer with lesions consistent with paratuberculosis at necropsy than was the ELISA-E (87.5%). In addition, the ELISA-A was particularly sensitive for detecting fallow deer in the latent stages of infection (62.5%). The antibody responses detected with the ELISA-A correlated with both the severity of enteric lesions and the presence of acid-fast bacteria in gut tissue samples. In summary, our study shows that the ELISA-A can be a cost-effective diagnostic tool for preventing the spread of paratuberculosis among fallow deer populations.

  8. Combined hepatitis C virus (HCV) antigen-antibody detection assay does not improve diagnosis for seronegative individuals with occult HCV infection.

    Science.gov (United States)

    Quiroga, Juan A; Castillo, Inmaculada; Pardo, Margarita; Rodríguez-Iñigo, Elena; Carreño, Vicente

    2006-12-01

    A combined hepatitis C virus (HCV) antigen-antibody assay was evaluated for 115 seronegative individuals with occult HCV infection. The assay was reactive in one patient and negative to weakly reactive in three others (all four gave indeterminate results by supplemental assay) but failed to detect HCV in the remaining patients. Despite increased sensitivity the combined assay does not improve serodiagnosis of occult HCV infection.

  9. Combined Hepatitis C Virus (HCV) Antigen-Antibody Detection Assay Does Not Improve Diagnosis for Seronegative Individuals with Occult HCV Infection▿

    OpenAIRE

    Quiroga, Juan A.; Castillo, Inmaculada; Pardo, Margarita; Rodríguez-Iñigo, Elena; CARREÑO, VICENTE

    2006-01-01

    A combined hepatitis C virus (HCV) antigen-antibody assay was evaluated for 115 seronegative individuals with occult HCV infection. The assay was reactive in one patient and negative to weakly reactive in three others (all four gave indeterminate results by supplemental assay) but failed to detect HCV in the remaining patients. Despite increased sensitivity the combined assay does not improve serodiagnosis of occult HCV infection.

  10. Preparation of Monoclonal Antibody and Development of Enzyme-linked Immunosorbent Assay Specific for Escherichia coli O157 in Foods

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Objective To prepare monoclonal antibodies (Mab) and antisera specific for Escherichia coli (E.coli) O157, and to develop a sandwich enzyme-linked immunosorbent assay (ELISA) to detect E.coli O157 in foods. Methods Spleen cells from BALB/c mice immunized with the somatic antigen of E.coli O157:H7 were fused with murine Sp2/0 myeloma cells. The hybridoma cell line specific for E.coli O157 was established after having been subcloned. Antisera specific for E.coli O157 was prepared by intravenous injection into New Zealand rabbits with a stain of E.coli O157:H7. The sandwich ELISA was developed with the polyclonal antibody as the capture antibody and the Mab 3A5 as the detection antibody. The inoculated ground poultry meat and pasteurized milk were tested to confirm efficiency of the method. Results Mab 3A5 specific for E.coli O157 and O113:H21 belonged to subtype IgM. The ascetic titers of the antibody was 1:1×106. No cross-reactivity of the Mab was observed with strains of Salmonella spp, Yersinia enterocolitica, Shigella dysenteriae, etc. The purified polyclonal antibody had a titer of 1:1×105 with E.coli O157. The detection limit of this sandwich ELISA was 103-104 cfu E.coli O157/mL in pure culture with a high specificity, which was characterized by every non-O157 strain with negative response. With 10h enrichment procedure, E.coli O157:H7 recovered well from inoculated ground poultry meat and pasteurized milk at levels of 0.1 cfu/g and 0.1 cfu/mL. Conclusion Mab 3A5 specific for E.coli O157 and O113:H21 can be produced by immunizing BALB/c mice with a strain of E.coli O157:H7. Then a sandwich ELISA can be developed with the polyclonal antibody as the capture antibody and the Mab 3A5 as the detection antibody. The method is proved to be a sensitive and specific technique to detect low number of E.coli O157 in food.

  11. LabKey Server NAb: A tool for analyzing, visualizing and sharing results from neutralizing antibody assays

    Directory of Open Access Journals (Sweden)

    Gao Hongmei

    2011-05-01

    Full Text Available Abstract Background Multiple types of assays allow sensitive detection of virus-specific neutralizing antibodies. For example, the extent of antibody neutralization of HIV-1, SIV and SHIV can be measured in the TZM-bl cell line through the degree of luciferase reporter gene expression after infection. In the past, neutralization curves and titers for this standard assay have been calculated using an Excel macro. Updating all instances of such a macro with new techniques can be unwieldy and introduce non-uniformity across multi-lab teams. Using Excel also poses challenges in centrally storing, sharing and associating raw data files and results. Results We present LabKey Server's NAb tool for organizing, analyzing and securely sharing data, files and results for neutralizing antibody (NAb assays, including the luciferase-based TZM-bl NAb assay. The customizable tool supports high-throughput experiments and includes a graphical plate template designer, allowing researchers to quickly adapt calculations to new plate layouts. The tool calculates the percent neutralization for each serum dilution based on luminescence measurements, fits a range of neutralization curves to titration results and uses these curves to estimate the neutralizing antibody titers for benchmark dilutions. Results, curve visualizations and raw data files are stored in a database and shared through a secure, web-based interface. NAb results can be integrated with other data sources based on sample identifiers. It is simple to make results public after publication by updating folder security settings. Conclusions Standardized tools for analyzing, archiving and sharing assay results can improve the reproducibility, comparability and reliability of results obtained across many labs. LabKey Server and its NAb tool are freely available as open source software at http://www.labkey.com under the Apache 2.0 license. Many members of the HIV research community can also access the Lab

  12. LabKey Server NAb: A tool for analyzing, visualizing and sharing results from neutralizing antibody assays

    Science.gov (United States)

    2011-01-01

    Background Multiple types of assays allow sensitive detection of virus-specific neutralizing antibodies. For example, the extent of antibody neutralization of HIV-1, SIV and SHIV can be measured in the TZM-bl cell line through the degree of luciferase reporter gene expression after infection. In the past, neutralization curves and titers for this standard assay have been calculated using an Excel macro. Updating all instances of such a macro with new techniques can be unwieldy and introduce non-uniformity across multi-lab teams. Using Excel also poses challenges in centrally storing, sharing and associating raw data files and results. Results We present LabKey Server's NAb tool for organizing, analyzing and securely sharing data, files and results for neutralizing antibody (NAb) assays, including the luciferase-based TZM-bl NAb assay. The customizable tool supports high-throughput experiments and includes a graphical plate template designer, allowing researchers to quickly adapt calculations to new plate layouts. The tool calculates the percent neutralization for each serum dilution based on luminescence measurements, fits a range of neutralization curves to titration results and uses these curves to estimate the neutralizing antibody titers for benchmark dilutions. Results, curve visualizations and raw data files are stored in a database and shared through a secure, web-based interface. NAb results can be integrated with other data sources based on sample identifiers. It is simple to make results public after publication by updating folder security settings. Conclusions Standardized tools for analyzing, archiving and sharing assay results can improve the reproducibility, comparability and reliability of results obtained across many labs. LabKey Server and its NAb tool are freely available as open source software at http://www.labkey.com under the Apache 2.0 license. Many members of the HIV research community can also access the LabKey Server NAb tool without

  13. Establishment and preliminary application of Dengue virus envelope domain Ⅲ IgG antibody capture enzyme-linked immuno-absorbent assay

    Institute of Scientific and Technical Information of China (English)

    胡冬梅

    2013-01-01

    Objective To establish a highly sensitive and specific assay to detect Dengue virus(DENV) envelope protein domainⅢ(EDⅢ) IgG antibody,and to explore its value in the diagnosis and seroepidemiological survey of dengue

  14. Comparison of enzyme-linked immunosorbent assays and virus neutralization test for detection of antibodies to avian pneumovirus.

    Science.gov (United States)

    Alkahalaf, A N; Halvorson, D A; Saif, Y M

    2002-01-01

    Two different whole-virus enzyme-linked immunosorbent assays (ELISAs), developed in Ohio (OH) with APV/Minnesota/turkey/2a/97 and in Minnesota (MN) with APV/Colorado/turkey/97, and the virus neutralization (VN) test were used to test 270 turkey serum samples from 27 Minnesota turkey flocks for avian pneumovirus (APV) antibodies. In addition, 77 turkey serum samples and 128 ostrich serum samples from Ohio were tested. None of the turkey samples from Ohio had antibodies to APV by the VN test and OH ELISA. The ostrich samples were only tested with the VN test and were all negative for antibodies to APV. For the Minnesota serum samples, 107, 115, and 120 were positive by the VN test, the OH ELISA, and the MN ELISA, respectively. The Kappa values of 0.938 and 0.825 showed excellent agreement between the VN test and the OH ELISA and the MN ELISA, respectively, for detection of antibodies to the APV. The OH ELISA and MN ELISA had sensitivities of 1.0 and 0.953, specificities of 0.950 and 0.889, and accuracies of 0.970 and 0.914, respectively. Our results indicate that the 3 methods are sensitive and specific for diagnosis of the APV infection.

  15. Production of mono- and polyclonal antibodies to Citrus leprosis virus C2 and their application in triple antibody sandwich ELISA and immunocapture RT-PCR diagnostic assays.

    Science.gov (United States)

    Choudhary, Nandlal; Roy, Avijit; Leon, M G; Wei, G; Nakhla, M K; Levy, L; Brlansky, R H

    2017-05-01

    The newly discovered Citrus leprosis virus cytoplasmic type 2 (CiLV-C2) is one of the causal virus of citrus leprosis disease complex; which leads to substantial loss of citrus production in the states of Meta and Casanare of Colombia. Specific and sensitive detection methods are needed to monitor the dissemination of CiLV-C2 in Colombia, and to prevent introduction of CiLV-C2 to other citrus growing countries. Toward this end, putative coat protein gene (CPG) of CiLV-C2 was amplified from CiLV-C2 infected citrus tissues. The CPG was cloned, expressed and purified a recombinant coat protein of ∼31kDa which used to generate monoclonal antibodies and polyclonal antisera. Four monoclonal antibodies and two polyclonal antisera were selected as being specific following Western blotting. The monoclonal antibody MAb E5 and polyclonal antiserum PAb UF715 were selected testing with an extract of CiLV-C2 infected leaves using triple antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA). In addition, an immunocapture RT-PCR was standardized using MAb E5 for specific and sensitive detection of CiLV-C2. The standardized TAS-ELISA and IC-RT-PCR were able to detect CiLV-C2 in the extracts of symptomatic citrus leprosis tissues up to the dilutions of 1:160 and 1:2580, respectively. Result demonstrated that CiLV-C2 is present in citrus orchards in Meta and Casanare citrus growing areas of Colombia. TAS-ELISA could be used for routine detection of CiLV-C2, epidemiological studies, and for border inspections for quarantine purposes. IC-RT-PCR could be valuable for CiLV-C2 validation and viral genome analysis.

  16. Seq4SNPs: new software for retrieval of multiple, accurately annotated DNA sequences, ready formatted for SNP assay design

    Directory of Open Access Journals (Sweden)

    Dunning Alison M

    2009-06-01

    Full Text Available Abstract Background In moderate-throughput SNP genotyping there was a gap in the workflow, between choosing a set of SNPs and submitting their sequences to proprietary assay design software, which was not met by existing software. Retrieval and formatting of sequences flanking each SNP, prior to assay design, becomes rate-limiting for more than about ten SNPs, especially if annotated for repetitive regions and adjacent variations. We routinely process up to 50 SNPs at once. Implementation We created Seq4SNPs, a web-based, walk-away software that can process one to several hundred SNPs given rs numbers as input. It outputs a file of fully annotated sequences formatted for one of three proprietary design softwares: TaqMan's Primer-By-Design FileBuilder, Sequenom's iPLEX or SNPstream's Autoprimer, as well as unannotated fasta sequences. We found genotyping assays to be inhibited by repetitive sequences or the presence of additional variations flanking the SNP under test, and in multiplexes, repetitive sequence flanking one SNP adversely affects multiple assays. Assay design software programs avoid such regions if the input sequences are appropriately annotated, so we used Seq4SNPs to provide suitably annotated input sequences, and improved our genotyping success rate. Adjacent SNPs can also be avoided, by annotating sequences used as input for primer design. Conclusion The accuracy of annotation by Seq4SNPs is significantly better than manual annotation (P Using Seq4SNPs to incorporate all annotation for additional SNPs and repetitive elements into sequences, for genotyping assay designer software, minimizes assay failure at the design stage, reducing the cost of genotyping. Seq4SNPs provides a rapid route for replacement of poor test SNP sequences. We routinely use this software for assay sequence preparation. Seq4SNPs is available as a service at http://moya.srl.cam.ac.uk/oncology/bio/s4shome.html and http://moya.srl

  17. Activity assays and immunoassays for plasma Renin and prorenin: information provided and precautions necessary for accurate measurement

    DEFF Research Database (Denmark)

    Campbell, Duncan J; Nussberger, Juerg; Stowasser, Michael

    2009-01-01

    BACKGROUND: Measurement of plasma renin is important for the clinical assessment of hypertensive patients. The most common methods for measuring plasma renin are the plasma renin activity (PRA) assay and the renin immunoassay. The clinical application of renin inhibitor therapy has thrown...... are susceptible to renin overestimation due to prorenin activation. In addition, activity assays performed with peptidase inhibitors may overestimate the degree of inhibition of PRA by renin inhibitor therapy. Moreover, immunoassays may overestimate the reactive increase in plasma renin concentration in response...

  18. A novel multi-walled carbon nanotube-based antibody conjugate for quantitative and semi-quantitative lateral flow assays.

    Science.gov (United States)

    Sun, Wenjuan; Hu, Xiaolong; Liu, Jia; Zhang, Yurong; Lu, Jianzhong; Zeng, Libo

    2017-10-01

    In this study, the multi-walled carbon nanotubes (MWCNTs) were applied in lateral flow strips (LFS) for semi-quantitative and quantitative assays. Firstly, the solubility of MWCNTs was improved using various surfactants to enhance their biocompatibility for practical application. The dispersed MWCNTs were conjugated with the methamphetamine (MET) antibody in a non-covalent manner and then manufactured into the LFS for the quantitative detection of MET. The MWCNTs-based lateral flow assay (MWCNTs-LFA) exhibited an excellent linear relationship between the values of test line and MET when its concentration ranges from 62.5 to 1500 ng/mL. The sensitivity of the LFS was evaluated by conjugating MWCNTs with HCG antibody and the MWCNTs conjugated method is 10 times more sensitive than the one conjugated with classical colloidal gold nanoparticles. Taken together, our data demonstrate that MWCNTs-LFA is a more sensitive and reliable assay for semi-quantitative and quantitative detection which can be used in forensic analysis.

  19. Rheumatoid factor interference in immunogenicity assays for human monoclonal antibody therapeutics.

    Science.gov (United States)

    Tatarewicz, Suzanna; Miller, Jill M; Swanson, Steven J; Moxness, Michael S

    2010-05-31

    Rheumatoid factors (RFs) are endogenous human antibodies that bind to human gamma globulins. RFs demonstrate preferential binding to aggregated gamma globulins and are involved in the clearing mechanism of immune complexes. Immunoassays designed to measure human anti-human antibodies (HAHA) after administration of monoclonal antibody therapeutics are thus vulnerable to interference from RFs. When using a sensitive electrochemiluminescent (ECL) bridging immunoassay, samples from subjects with rheumatoid arthritis demonstrated much higher baseline reactivity than healthy subjects. Interference was found to be dependent on the aggregation state of the therapeutic antibody that had been conjugated with the detection reagent (ruthenium). Size exclusion high performance liquid chromatography (SE-HPLC) demonstrated that of the total integrated peaks, as little as 0.55% high molecular weight aggregates (>600kDa) were sufficient to cause increased reactivity. Stability studies of the ruthenium and biotin conjugated therapeutic antibody indicated that storage time, temperature and buffer formulation were critical in maintaining the integrity of the reagents. Through careful SE-HPLC monitoring we were able to choose appropriate storage and buffer conditions which led to a reduction in the false reactivity rate in therapeutic-naïve serum from a rheumatoid arthritis population.

  20. An improved haemolytic plaque assay for the detection of cells secreting antibody to bacterial antigens

    DEFF Research Database (Denmark)

    Barington, T; Heilmann, C

    1992-01-01

    SC with specificity for tetanus and diphtheria toxoid as well as for Haemophilus influenzae type b and pneumococcal capsular polysaccharides. These assays were found to be less time consuming, more economical and yielded 1.9-3.4-fold higher plaque numbers than traditional Jerne-type PFC assays. In the case of anti...

  1. Measuring Immunoglobulin G Antibodies to Tetanus Toxin, Diphtheria Toxin, and Pertussis Toxin with Single-Antigen Enzyme-Linked Immunosorbent Assays and a Bead-Based Multiplex Assay▿

    OpenAIRE

    Reder, Sabine; Riffelmann, Marion; Becker, Christian; Wirsing von König, Carl Heinz

    2008-01-01

    Bead-based assay systems offer the possibility of measuring several specific antibodies in one sample simultaneously. This study evaluated a vaccine panel of a multianalyte system that measures antibodies to tetanus toxin, diphtheria toxin, and pertussis toxin (PT) from Bordetella pertussis. The antibody concentrations of human immunoglobulin G (IgG) to PT, tetanus toxin, and diphtheria toxin were measured in 123 serum pairs (total of 246 sera) from a vaccine study. The multianalyte bead assa...

  2. The role of complement-fixing donor specific antibodies identified by a C1q assay after heart transplantation.

    Science.gov (United States)

    Farrero Torres, M; Pando, M J; Luo, C; Luikart, H; Valantine, H; Khush, K

    2017-09-22

    The development of donor-specific antibodies (DSA) to human leukocyte antigens (HLA) has been associated with acute rejection and allograft failure after heart transplantation. Not all DSA, however, can fix complement. To determine the association between complement-fixing DSA and heart transplant outcomes, we retrospectively analyzed results obtained using the C1q solid-phase assay that specifically detects complement-fixing DSA in parallel with the standard IgG assay in 121 adult heart transplant recipients. The 52 recipients who developed post-transplant DSA had a higher incidence of acute cellular rejection (58% vs. 19%, p<0.001) and antibody-mediated rejection (29% vs. 7%, p<0.001) than the 69 recipients without DSA. The 24 recipients with C1q+ DSA had more antibody mediated rejection than the 28 recipients with C1q- DSA (46% vs. 14%, p=0.012), but there was no difference in the incidence of acute cellular rejection between these two groups. Patients with post-transplant DSA had higher mortality than patients with no DSA (29% vs. 13%, p=0.031), mainly due to increased incidence of acute rejection. No differences in survival were found between recipients with C1q+ DSA and C1q- DSA. Routine monitoring of DSA post-transplant, and their characterization using the C1q assay, may provide prognostic information for acute rejection after heart transplantation. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  3. Evaluation and optimization of a commercial enzyme linked immunosorbent assay for detection of Chlamydophila pneumoniae IgA antibodies

    Directory of Open Access Journals (Sweden)

    Gargouri Jalel

    2008-07-01

    Full Text Available Abstract Background Serologic diagnosis of Chlamydophila pneumoniae (Cpn infection routinely involves assays for the presence of IgG and IgM antibodies to Cpn. Although IgA antibodies to Cpn have been found to be of interest in the diagnosis of chronic infections, their significance in serological diagnosis remains unclear. The microimmunofluorescence (MIF test is the current method for the measurement of Cpn antibodies. While commercial enzyme linked immunosorbent assays (ELISA have been developed, they have not been fully validated. We therefore evaluated and optimized a commercial ELISA kit, the SeroCP IgA test, for the detection of Cpn IgA antibodies. Methods Serum samples from 94 patients with anti-Cpn IgG titers ≥ 256 (study group and from 100 healthy blood donors (control group were tested for the presence of IgA antibodies to Cpn, using our in-house MIF test and the SeroCP IgA test. Two graph receiver operating characteristic (TG-ROC curves were created to optimize the cut off given by the manufacturer. Results The MIF and SeroCP IgA tests detected Cpn IgA antibodies in 72% and 89%, respectively, of sera from the study group, and in 9% and 35%, respectively, of sera from the control group. Using the MIF test as the reference method and the cut-off value of the ELISA test specified by the manufacturer for seropositivity and negativity, the two tests correlated in 76% of the samples, with an agreement of Ƙ = 0.54. When we applied the optimized cut-off value using TG-ROC analysis, 1.65, we observed better concordance (86% and agreement (0.72 between the MIF and SeroCP IgA tests. Conclusion Use of TG-ROC analysis may help standardize and optimize ELISAs, which are simpler, more objective and less time consuming than the MIF test. Standardization and optimization of commercial ELISA kits may result in better performance.

  4. A multiplex assay for the quantification of antibody responses in Staphylococcus aureus infections in mice

    NARCIS (Netherlands)

    van den Berg, Sanne; Bowden, M. Gabriela; Bosma, Tjibbe; Buist, Girbe; van Dijl, Jan Maarten; van Wamel, Willem J.; de Vogel, Corne P.; van Belkum, Alex; Bakker-Woudenberg, Irma A. J. M.

    2011-01-01

    Staphylococcus aureus causes a variety of infections. Knowledge about the physiological role of most S. aureus antigens in colonization and infection is only limited. This can be studied by measuring antigen-specific antibody responses. In this study, we optimized the multiplex microsphere

  5. An indirect enzyme-linked immunosorbent assay for the identification of antibodies to Senecavirus A in swine.

    Science.gov (United States)

    Dvorak, Cheryl M T; Akkutay-Yoldar, Zeynep; Stone, Suzanne R; Tousignant, Steven J P; Vannucci, Fabio A; Murtaugh, Michael P

    2017-02-15

    Senecavirus A (SVA), a member of the family Picornaviridae, genus Senecavirus, is a recently identified single-stranded RNA virus closely related to members of the Cardiovirus genus. SVA was originally identified as a cell culture contaminant and was not associated with disease until 2007 when it was first observed in pigs with Idiopathic Vesicular Disease (IVD). Vesicular disease is sporadically observed in swine, is not debilitating, but is significant due to its resemblance to foreign animal diseases, such as foot-and-mouth disease (FMD), whose presence would be economically devastating to the United States. IVD disrupts swine production until foreign animal diseases can be ruled out. Identification and characterization of SVA as a cause of IVD will help to quickly rule out infection by foreign animal diseases. We have developed and characterized an indirect ELISA assay to specifically identify serum antibodies to SVA. Viral protein 1, 2 and 3 (VP1, VP2, VP3) were expressed, isolated, and purified from E. coli and used to coat plates for an indirect ELISA. Sera from pigs with and without IVD symptoms as well as a time course following animals from an infected farm, were analyzed to determine the antibody responses to VP1, VP2, and VP3. Antibody responses to VP2 were higher than VP1 and VP3 and showed high affinity binding on an avidity ELISA. ROC analysis of the SVA VP2 ELISA showed a sensitivity of 94.2% and a specificity of 89.7%. Compared to IFA, the quantitative ELISA showed an 89% agreement in negative samples and positive samples from 4-60 days after appearance of clinical signs. Immune sera positive for FMDV, encephalomyocarditis virus, and porcine epidemic diarrhea virus antibodies did not cross-react. A simple ELISA based on detection of antibodies to SVA VP2 will help to differentially diagnose IVD due to SVA and rule out the presence of economically devastating foreign animal diseases.

  6. Establishment of an Enzyme-linked Immunosorbent Assay for Thyroglobulin Antibody

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Thyroglobulin is coated on the microtiter plate and labeled with horseradish peroxidase(HRP). Thetwo-step assay is established based on enzyme-linked immunosorbent assay(ELISA). TMB-H2O2 solution

  7. A Simple and Accurate Way to Assay the Concentration of Nitric Acid——Back-titration Method

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Using 1mol/L (NH4)2SO4-aturated (NH4)2C2O4 as a masking reagent, V-△V/△pH, V-pH and back-titration methods are used to assay the concentration of nitric acid under various conditions and theresults are compared with that from phenolphthalein indicator method. It is shown that the data treatment

  8. Antibodies to immunoglobulin-G in dog sera, synovial fluids and aqueous humor : a comparative study of rheumatoid factor assays, suitable for routine application

    NARCIS (Netherlands)

    Bernadina, W.E.; Kol, P.J. van; Willemse, A.

    1988-01-01

    The incidence of anti-IgG antibodies (rheumatoid factors, RF) in body fluids (sera, synovial fluids and aqueous humor) selected from 62 normal and 275 diseased dogs was studied. Fluids were assayed by canine versions of standard agglutinating and/or precipitating RF assays with routine application i

  9. Biotin radioligand assay with an /sup 125/I-labeled biotin derivative, avidin, and avidin double-antibody reagents

    Energy Technology Data Exchange (ETDEWEB)

    Livaniou, E.; Evangelatos, G.P.; Ithakissios, D.S.

    1987-11-01

    We describe a new radioligand assay for determining biotin in biological fluids by using a mixture of N-(beta-(4-OH-3-125I-phenyl)ethyl)- and N-(beta-(4-OH-3,5-di-125I-phenyl)ethyl)biotinamides as radiotracer, avidin as a binding protein, and an avidin double-antibody as a separation reagent. The radiotracer is synthesized by coupling (at pH 8.5, 20-22 degrees C, 90 min) N-hydroxysuccinimidobiotin to radioiodinated tyramine. The assay curve is linear and the assay itself is sensitive (less than 10 ng/L), reproducible (intra- and interassay CVs 4.1% and 7.0%, respectively), and allows the simultaneous handling of more than 100 samples in less than 4 h. Serum samples from apparently normal subjects contained 100-840 ng of biotin per liter (mean 340 ng/L). Pregnant women had low concentrations of biotin (100-300 ng/L) in their serum. Patients undergoing chronic hemodialysis treatment showed high concentrations (0.5-3.0 micrograms/L), which may be ascribable to the inability of avidin, which was used as the assay binding protein, to distinguish biotin from biotinyl derivatives with an intact ureido ring.

  10. Development of a bead-based Luminex assay using lipopolysaccharide specific monoclonal antibodies to detect biological threats from Brucella species.

    Science.gov (United States)

    Silbereisen, Angelika; Tamborrini, Marco; Wittwer, Matthias; Schürch, Nadia; Pluschke, Gerd

    2015-10-05

    Brucella, a Gram-negative bacterium, is classified as a potential bioterrorism agent mainly due to the low dose needed to cause infection and the ability to transmit the bacteria via aerosols. Goats/sheep, cattle, pigs, dogs, sheep and rodents are infected by B. melitensis, B. abortus, B. suis, B. canis, B. ovis and B. neotomae, respectively, the six classical Brucella species. Most human cases are caused by B. melitensis and B. abortus. Our aim was to specifically detect Brucellae with 'smooth' lipopolysaccharide (LPS) using a highly sensitive monoclonal antibody (mAb) based immunological assay. To complement molecular detection systems for potential bioterror agents, as required by international biodefense regulations, sets of mAbs were generated by B cell hybridoma technology and used to develop immunological assays. The combination of mAbs most suitable for an antigen capture assay format was identified and an immunoassay using the Luminex xMAP technology was developed. MAbs specific for the LPS O-antigen of Brucella spp. were generated by immunising mice with inactivated B. melitensis or B. abortus cells. Most mAbs recognised both B. melitensis and B. abortus and antigen binding was not impeded by inactivation of the bacterial cells by γ irradiation, formalin or heat treatment, a step required to analyse the samples immunologically under biosafety level two conditions. The Luminex assay recognised all tested Brucella species with 'smooth' LPS with detection limits of 2×10(2) to 8×10(4) cells per mL, depending on the species tested. Milk samples spiked with Brucella spp. cells were identified successfully using the Luminex assay. In addition, the bead-based immunoassay was integrated into a multiplex format, allowing for simultaneous, rapid and specific detection of Brucella spp., Bacillus anthracis, Francisella tularensis and Yersinia pestis within a single sample. Overall, the robust Luminex assay should allow detection of Brucella spp. in both natural

  11. High Yield Purification of Plasmodium falciparum Merozoites For Use in Opsonizing Antibody Assays

    OpenAIRE

    Hill, Danika L.; Eriksson, Emily M.; Schofield, Louis

    2014-01-01

    Plasmodium falciparum merozoite antigens are under development as potential malaria vaccines. One aspect of immunity against malaria is the removal of free merozoites from the blood by phagocytic cells. However assessing the functional efficacy of merozoite specific opsonizing antibodies is challenging due to the short half-life of merozoites and the variability of primary phagocytic cells. Described in detail herein is a method for generating viable merozoites using the E64 protease inhibito...

  12. Indirect enzyme-linked immunosorbent assay for detection of Brucella melitensis-specific antibodies in goat milk.

    Science.gov (United States)

    Funk, N D; Tabatabai, L B; Elzer, P H; Hagius, S D; Martin, B M; Hoffman, L J

    2005-02-01

    Brucella melitensis is the cause of brucellosis in sheep and goats, which often results in abortion. Few cases of B. melitensis infection in goats have occurred in the United States over the last 25 years. However, vigilance must be maintained, as it is for the bovine milk industry, to ensure that brucellosis is not introduced into the U.S. goat population. The objective of this study was to develop a sensitive and specific indirect enzyme-linked immunosorbent assay (iELISA) for the detection of B. melitensis-specific antibodies in goat milk. Brucella salt-extractable protein extract was employed as an antigen, and a horseradish peroxidase-labeled polyclonal anti-goat antibody was used as an anti-species conjugate. Thirteen of 13 (100%) individual infected goat milk samples tested positive and 134 of 134 (100%) uninfected bulk milk samples tested negative by the developed iELISA. Three positive milk samples with high, medium, and low absorbance values were used to simulate one positive animal in an otherwise negative herd. By this estimation, one high-titer animal could be detected in a herd of >1,600 animals. Detection estimates for medium- and low-titer animals were one positive animal per herd of melitensis-specific antibodies in goat milk.

  13. Detection of drug-dependent, platelet-reactive antibodies by solid-phase red cell adherence assays.

    Science.gov (United States)

    Leach, M F; Cooper, L K; AuBuchon, J P

    1997-06-01

    We developed a simple modification of the solid-phase red cell adherence (SPRCA) assay system that can be used to identify drug-dependent platelet antibodies (DDPAs) reactive by either the hapten or immune complex reaction mechanisms. Between January 1994 and August 1996 we tested sera from 173 patients [123 (71%) with unexplained thrombocytopenia and 50 (29%) because of poor responses to platelet transfusions not explicable by alloimmunization or the clinical situation] for DDPAs possibly associated with the receipt of 61 different drugs. We correlated positive results with patients' clinical courses. DDPAs were identified in samples from 138 (80%) of the patients tested. Antibodies reactive only by the hapten mechanism were identified in 51 (37%) of those sera exhibiting positive reactions. The clinical courses of 108 (78%) patients were evaluable. Discontinuation of the implicated drug(s) resulted in prompt (<5 d) resolution of the thrombocytopenia or improvement in response to transfusion in all of these patients. In four cases thrombocytopenia returned upon re-exposure to the implicated drug. This adaptation of SPRCA provides a simple means of investigating the possibility of DDPAs and documents a higher frequency of these antibodies than has previously been suspected.

  14. A semi-automated multiplex high-throughput assay for measuring IgG antibodies against Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) domains in small volumes of plasma

    DEFF Research Database (Denmark)

    Cham, Gerald K K; Kurtis, Jonathan; Lusingu, John;

    2008-01-01

    BACKGROUND: The level of antibodies against PfEMP1 is routinely quantified by the conventional microtitre enzyme-linked immunosorbent assay (ELISA). However, ELISA only measures one analyte at a time and requires a relatively large plasma volume if the complete antibody profile of the sample...... of twenty nine PfEMP1 domains were PCR amplified from 3D7 genomic DNA, expressed in the Baculovirus system and purified by metal-affinity chromatography. The antibody reactivity level to the recombinant PfEMP1 proteins in human hyper-immune plasma was measured by ELISA. In parallel, these recombinant PfEMP1......-based assay was sensitive, accurate and reproducible. Four recombinant PfEMP1 proteins C17, D5, D9 and D12, selected on the basis that they showed a spread of median fluorescent intensity (MFI) values from low to high when analysed by the bead-based assay were analysed by ELISA and the results from both...

  15. Performance of three microimmunofluorescence assays for detection of Chlamydia pneumoniae immunoglobulin M, G, and A antibodies

    DEFF Research Database (Denmark)

    Bennedsen, Mette; Berthelsen, Lene; Lind, Inga

    2002-01-01

    The microimmunofluorescence (MIF) test is considered the "gold standard" for laboratory diagnosis of acute and chronic Chlamydia pneumoniae infection. The performance of a MIF test based on C. pneumoniae antigen from Washington Research Foundation (WRF) was compared with those of assays from Labs...

  16. An automated packed protein G micro-pipette tip assay for rapid quantification of polyclonal antibodies in ovine serum.

    Science.gov (United States)

    Chhatre, Sunil; Francis, Richard; Bracewell, Daniel G; Titchener-Hooker, Nigel J

    2010-11-15

    The demands on the biopharmaceutical sector to expedite process development have instigated the deployment of micro-biochemical engineering techniques to acquire manufacturing insight with extremely small sample volumes. In conjunction with automated liquid handlers, this permits the simultaneous evaluation of multiple operating conditions and reduces manual intervention. For these benefits to be sustained, novel ways are now required to accelerate analysis and so prevent this becoming a throughput bottleneck. For example, although Protein G HPLC is used to quantify antibody titres in bioprocess feedstocks, it can be time-consuming owing to the serial nature of its application. Although commercial options are available that can process many samples simultaneously, these require separate, potentially expensive instruments. A more integrated approach is desirable wherein the assay is implemented directly on a robot. This article describes a high-throughput alternative to antibody HPLC analysis which uses an eight-channel liquid handler to control pipette tips packed with 40 μL of Protein G affinity matrix. The linearity, range, limit of detection, specificity and precision of the method were established, with results showing that antibody was detected reliably and specifically between 0.10 and 1.00 mg/mL. Subsequently, the technique was used to quantify the antibody titre in ovine serum, which is used as feed material by BTG PLC for manufacturing FDA-approved polyclonal bio-therapeutics. The mean concentration determined by the tips was comparable to that found by HPLC, but the tip method delivered its results in less than 40% of the time and with the potential for further, substantial time-savings possible by using higher capacity robots.

  17. Feasibility studies for assaying alpha-fetoprotein using antibody-activated magnetic nanoparticles

    Directory of Open Access Journals (Sweden)

    Huang KW

    2012-04-01

    Full Text Available Kai-Wen Huang1, Shieh-Yueh Yang2,3, Yu-Wei Hong3, Jen-Jie Chieh3, Che-Chuan Yang3, Herng-Er Horng3, Chau-Chung Wu4, Chin-Yih Hong5, Hong-Chang Yang61Department of Surgery and Hepatitis Research Center, National Taiwan University Hospital, National Taiwan University, Taipei, 2MagQu Co, Ltd, Sindian Dist, New Taipei City, 3Institute of Electro-optical Science and Technology, National Taiwan Normal University, Taipei, 4Departments of Internal Medicine and Primary Care Medicine, College of Medicine, National Taiwan University, Taipei, 5Graduate Institute of Bio-medical Engineering, National Chung Hsing University, Taichung, 6Department of Physics, National Taiwan University, Taipei, TaiwanAbstract: Some previous reports have already shown the characterizations of immunomagnetic reduction (IMR. The assay technology involves the utilities of biofunctionalized magnetic nanoparticles to label target biomolecules. However, the detection threshold and interference tests for IMR have not been investigated in detail. In this study, alpha-fetoprotein (AFP was used as a target biomolecule. The signals for AFP solutions of various concentrations, or with interfering materials, were detected via IMR. These samples were also used for characterizing the detection threshold and interference with enzyme-linked immunosorbent assay (ELISA. The results of assaying AFP level with IMR and ELISA were compared. The detection threshold for assaying AFP with IMR was found to be 3 ng/mL, which is 15 times lower than that of ELISA, and definitely suppresses false negative. For the interfering materials noted commonly in serum such as hemoglobin, bilirubin, triglyceride, and vascular endothelial growth factor, there was no detectable interfering effect when assaying AFP with IMR. Several serum samples from normal people and liver-tumor-bearing patients were used for the detections of AFP concentration via IMR. These results reveal the feasibilities of assaying AFP in blood

  18. Accurate and sensitive liquid chromatography/tandem mass spectrometry simultaneous assay of seven steroids in monkey brain.

    Science.gov (United States)

    Bertin, Jonathan; Dury, Alain Y; Ke, Yuyong; Ouellet, Johanne; Labrie, Fernand

    2015-06-01

    Following its secretion mainly by the adrenal glands, dehydroepiandrosterone (DHEA) acts primarily in the cells/tissues which express the enzymes catalyzing its intracellular conversion into sex steroids by the mechanisms of intracrinology. Although reliable assays of endogenous serum steroids are now available using mass spectrometry (MS)-based technology, sample preparation from tissue matrices remains a challenge. This is especially the case with high lipid-containing tissues such as the brain. With the combination of a UPLC system with a sensitive tandem MS, it is now possible to measure endogenous unconjugated steroids in monkey brain tissue. A Shimadzu UPLC LC-30AD system coupled to a tandem MS AB Sciex Qtrap 6500 system was used. The lower limits of quantifications are achieved at 250 pg/mL for DHEA, 200 pg/mL for 5-androstenediol (5-diol), 12 pg/mL for androstenedione (4-dione), 50 pg/mL for testosterone (Testo), 10 pg/mL for dihydrotestosterone (DHT), 4 pg/mL for estrone (E1) and 1 pg/mL for estradiol (E2). The linearity and accuracy of quality controls (QCs) and endogenous quality controls (EndoQCs) are according to the guidelines of the regulatory agencies for all seven compounds. We describe a highly sensitive, specific and robust LC-MS/MS method for the simultaneous measurement of seven unconjugated steroids in monkey brain tissue. The single and small amount of sample required using a relatively simple preparation method should be useful for steroid assays in various peripheral tissues and thus help analysis of the role of locally-made sex steroids in the regulation of specific physiological functions. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. A feasible enzyme-linked immunosorbent assay system using monoclonal and polyclonal antibodies against glucosyltransferase-B from Streptococcus mutans.

    Science.gov (United States)

    Shinozaki-Kuwahara, Noriko; Hashizume-Takizawa, Tomomi; Hirasawa, Masatomo; Takada, Kazuko

    2012-06-01

    Streptococcus mutans has been considered the principal etiological agent of dental caries in humans. S. mutans can secrete three kinds of glucosyltransferases (GTFs). One of these, GTF-B, which synthesizes water-insoluble glucans from sucrose, has been considered to be one of the most important factors of cariogenic dental plaque formation. Therefore, determination of whether GTF-B is present in plaque and saliva samples may contribute to the evaluation of individual virulence potential (caries risk). The aim of this study was to develop a feasible enzyme-linked immunosorbent assay (ELISA) for the routine quantification of GTF-B in plaque-derived cultures and clinical samples, and to apply this assay to an epidemiological study. To determine the presence of GTF-B in plaque samples, a sandwich-ELISA was devised, consisting of mouse monoclonal and rabbit polyclonal antibodies against GTF-B and a horseradish peroxidase-conjugated anti-rabbit antibody. The developed ELISA allowed for quantification of the amounts of purified GTF-B with satisfactory sensitivity and specificity; this method was not affected by other components such as plaque and saliva. Plaque samples from healthy volunteers were examined using this ELISA method and microbial analysis to apply the assay to an epidemiological study. A correlation was observed between the amount of extracted GTF-B and S. mutans levels as determined by ELISA and cultivated with Mitis Salivarius Bacitracin agar plates derived from plaque samples, although there were some exceptions. In this regard, this ELISA system has the advantage of estimating both the individual numbers of S. mutans and the productivity of GTF-B, namely, the cariogenic potential of S. mutans simultaneously. These results indicate that this ELISA method is a useful tool for the diagnosis of caries risk.

  20. Antibodies to fibrillarin, PM-Scl and RNA polymerase III detected by ELISA assays in patients with systemic sclerosis.

    Science.gov (United States)

    Villalta, Danilo; Morozzi, Gabriella; Tampoia, Marilina; Alpini, Claudia; Brusca, Ignazio; Salgarolo, Valeria; Papisch, Wolfgang; Bizzaro, Nicola

    2010-05-02

    Anti-fibrillarin (AFA), anti-RNA polymerase (anti-RNAP), and anti-PM-Scl autoantibodies are useful markers for the diagnosis of systemic sclerosis (SSc) in patients who are anti-centromere- (ACA) or anti-topoisomerase I (anti-topo I)-negative, but, until recently, the only specific method for their identification was the radio-immunoprecipitation assay. The aim of this study was to evaluate the clinical accuracy of the new enzyme-linked immunosorbent assays (ELISA) developed by Phadia for their detection. Sera of 50 ACA and anti-topo I-negative SSc patients, and, as control group, sera of 122 patients (42 with SSc, ACA or anti-topo I-positive, 40 with systemic lupus erythematosus and 40 with rheumatoid arthritis) were studied. Using the cutoff proposed by the manufacturer (10 AU/mL), sensitivity and specificity were: for AFA, 22% and 92.6%; for anti-RNAP, 16% and 97.5%; and for anti-PM-Scl, 8% and 98.8%, respectively. Using a cutoff corresponding to 98.8% specificity for all three antibodies, sensitivity was 10%, 14% and 8%, respectively. The combined use of these three antibody assays enabled identification of 32% of ACA- and anti-topo I-negative SSc patients. These new ELISA methods for AFA, anti-RNAP III and anti-PM-Scl detection have good diagnostic specificity, and may help identify a subset of SSc patients ACA and anti-topo I-negative. Copyright 2010 Elsevier B.V. All rights reserved.

  1. An Innovative Pseudotypes-Based Enzyme-Linked Lectin Assay for the Measurement of Functional Anti-Neuraminidase Antibodies.

    Directory of Open Access Journals (Sweden)

    Marua Prevato

    Full Text Available Antibodies (Ab to neuraminidase (NA play a role in limiting influenza infection and might help reduce the disease impact. The most widely used serological assay to measure functional anti-NA immune responses is the Enzyme-Linked Lectin Assay (ELLA which relies on hemagglutinin (HA mismatched virus reassortants, or detergent treated viruses as the NA source to overcome interference associated with steric hindrance of anti-HA Ab present in sera. The difficulty in producing and handling these reagents, which are not easily adapted for screening large numbers of samples, limits the routine analysis of functional anti-NA Ab in clinical trials. In this study, we produced influenza lentiviral pseudoparticles (PPs containing only the NA antigen (NA-PPs with a simple two-plasmid co-transfection system. NA-PPs were characterized and tested as an innovative source of NA in the NA inhibition (NI assay. Both swine A/California/07/2009 (H1N1 and avian A/turkey/Turkey/01/2005 (H5N1 N1s within NA-PPs retained their sialidase activity and were specifically inhibited by homologous and N1 subtype-specific, heterologous sheep sera. Moreover, A/California/07/2009 N1-PPs were a better source of NA compared to whole live and detergent treated H1N1 viruses in ELLA, likely due to lack of interference by anti-HA Ab, and absence of possible structural modifications caused by treatment with detergent. This innovative assay is safer and applicable to all NAs. Taken together, these results highlight the potential of NA-PPs-based NI assays to be developed as sensitive, flexible, easy to handle and scalable serological tests for routine NA immune response analysis.

  2. Development of a Rapid Qualitative Assay for Determining Elevated Antibody Levels to Periodontopathic Organisms

    Science.gov (United States)

    1990-01-01

    another report, showed no elevation in IgM or IgA in these patients, with some-elevation of total~lgG (Rahney et’aL. 1981)’. Murray & Genco (1980) found...leukotoxic activity compared to 24% of normal, 39%of adult periodontitis,.,and 38% of ANUG sera. Genco et at. (1980b) found that.89% of LJP patients...Aactinomycetemcomitans have been notedin patients with rapidly progressive disease ( Genco et al. 1985). Theserum antibody response in adult periodontitis is more

  3. Thrombotic risk assessment in antiphospholipid syndrome the role of new antibody specificities and thrombin generation assay

    DEFF Research Database (Denmark)

    Sciascia, Savino; Baldovino, Simone; Schreiber, Karen

    2016-01-01

    Antiphospholipid syndrome (APS) is an autoimmune condition characterized by the presence of antiphospholipid antibodies (aPL) in subjects presenting with thrombosis and/or pregnancy loss. The currently used classification criteria were updated in the international consensus held in Sidney in 2005....... Vascular events seem to result of local procoagulative alterations upon triggers influence (the so called "second-hit theory"), while placental thrombosis and complement activation seem to lead to pregnancy morbidity. The laboratory tests suggested by the current classification criteria include lupus...

  4. Thaw-and-use target cells pre-labeled with calcein AM for antibody-dependent cell-mediated cytotoxicity assays.

    Science.gov (United States)

    Chung, Shan; Nguyen, Van; Lin, Yuwen Linda; Kamen, Lynn; Song, An

    2017-08-01

    In vitro antibody-dependent cell-mediated cytotoxicity (ADCC) assays are routinely performed to support the research and development of therapeutic antibodies. In ADCC assays, target cells bound by the antibodies are lysed by activated effector cells following interactions between the Fc region of the bound antibody and Fcγ receptors on effector cells. Target cell lysis is typically measured by quantification of released endogenous enzymes, e.g., lactate dehydrogenase, or measurement of released exogenous labels, e.g., (51)Cr, europium or calcein. ADCC assays based on the detection of exogenous labels released from lysed target cells generally show higher sensitivity and require shorter incubation times. However, target cells are usually labeled immediately prior to assay, which inadvertently introduces additional assay variations due to differences in target cell conditions and labeling/handling processes. In this report, we describe the use of thaw-and-use pre-labeled target cells for ADCC assays. Thaw-and-use target cells in our experiments were pre-labeled with the fluorescent dye calcein AM, cryopreserved in single-use aliquots and used directly in assays after thawing. Upon thaw, the pre-labeled cells displayed viability and label retention comparable to freshly labeled cells, responded to ADCC mediated by both peripheral blood mononuclear cells and engineered natural killer cells, performed stably for at least 3 years and provided favorable precision and accuracy to ADCC assays. Implementation of thaw-and-use pre-labeled target cells in ADCC assays can help to alleviate both cell culture and dye labeling derived variability, increase the flexibility of assay scheduling and improve assay consistency and robustness. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. An indirect competitive enzyme-linked immunosorbent assay for determination of norfloxacin in waters using a specific polyclonal antibody.

    Science.gov (United States)

    Cui, Jianlan; Zhang, Kun; Huang, Qiuxin; Yu, Yiyi; Peng, Xianzhi

    2011-02-28

    A specific polyclonal anti-norfloxacin antibody was obtained, and a sensitive indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed for determining trace amounts of norfloxacin in various waters. Good linearity was achieved in the range from 0.1 to 10 μg L(-1). The average IC(50) value was determined to be 2.2 μg L(-1) and the limit of detection was 0.016 μg L(-1) at a signal-to-noise ratio of 3 in phosphate-buffered saline buffer. Recoveries of norfloxacin at various spiking levels ranged from 74 to 105% in groundwater, surface water, treated and untreated wastewater samples, with relative standard deviations of 3-5%. The assay was applied for determining norfloxacin in municipal wastewater, surface water, and groundwater collected in a metropolis of China. Raw wastewater samples were only submitted to filtration and pH adjustment while the other water samples were pre-concentrated by solid phase extraction prior to the icELISA assay. Good agreement of the results obtained by the icELISA and liquid chromatography tandem mass spectrometry further confirmed the reliability and accuracy of the icELISA for rapid detection of norfloxacin in waters. Copyright © 2010 Elsevier B.V. All rights reserved.

  6. Novel Monoclonal Antibody-Based Immunodiagnostic Assay for Rapid Detection of Deamidated Gluten Residues.

    Science.gov (United States)

    Masiri, Jongkit; Benoit, Lora; Katepalli, Madhu; Meshgi, Mahzad; Cox, David; Nadala, Cesar; Sung, Shao-Lei; Samadpour, Mansour

    2016-05-11

    Gluten derived from wheat and related Triticeae can induce gluten sensitivity as well as celiac disease. Consequently, gluten content in foods labeled "gluten-free" is regulated. Determination of potential contamination in such foods is achieved using immunoassays based on monoclonal antibodies (mAbs) that recognize specific epitopes present in gluten. However, food-processing measures can affect epitope recognition. In particular, preparation of wheat protein isolate through deamidation of glutamine residues significantly limits the ability of commercial gluten testing kits in their ability to recognize gluten. Adding to this concern, evidence suggests that deamidated gluten imparts more pathogenic potential in celiac disease than native gluten. To address the heightened need for antibody-based tools that can recognize deamidated gluten, we have generated a novel mAb, 2B9, and subsequently developed it as a rapid lateral flow immunoassay. Herein, we report the ability of the 2B9-based lateral flow device (LFD) to detect gluten from wheat, barley, and rye and deamidated gluten down to 2 ppm in food as well as its performance in food testing.

  7. The standard mouse assay of anti-venom quality does not measure antibodies neutralising the haemorrhagic activity of Vipera ammodytes venom.

    Science.gov (United States)

    Kurtović, Tihana; Leonardi, Adrijana; Lang Balija, Maja; Brgles, Marija; Habjanec, Lidija; Križaj, Igor; Halassy, Beata

    2012-06-01

    The venom of Vipera ammodytes ammodytes (Vaa), like the venoms of other Viperinae snakes, is largely haemorrhagic and necrotising, and only to a lesser extent neurotoxic to humans. The components most extensively studied so far, and most probably involved in generating the observed pathologies, are haemorrhagins (H), members of the metalloproteinase group of enzymes, and neurotoxic ammodytoxins (Atxs), that belong to the secretory phospholipases A2. Rabbit antisera were prepared containing functional antibodies specific for each class of pathology-inducing venom constituents and for both classes together. The involvement of these antibodies in neutralising the toxicity of whole Vaa venom was assessed using the ED50 assay in mice. This assay is the only regulatorily approved assay for estimating anti-venom potency and as such has the task to quantify the active compound neutralising venom-induced pathology of the anti-venom. Fully functional anti-Atx antibodies were shown to be responsible for neutralising the portion of venom toxicity, while anti-H antibodies were not protective in this assay. Thus, the mouse ED50 assay, intended to measure the active principle of the anti-venom, does not measure antibodies specific for Vaa venom haemorrhagins, and consequently does not fulfil its primary task from the regulatory point of view. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Isothermal microcalorimetry accurately detects bacteria, tumorous microtissues, and parasitic worms in a label-free well-plate assay.

    Science.gov (United States)

    Braissant, Olivier; Keiser, Jennifer; Meister, Isabel; Bachmann, Alexander; Wirz, Dieter; Göpfert, Beat; Bonkat, Gernot; Wadsö, Ingemar

    2015-03-01

    Isothermal microcalorimetry is a label-free assay that allows monitoring of enzymatic and metabolic activities. The technique has strengths, but most instruments have a low throughput, which has limited their use for bioassays. Here, an isothermal microcalorimeter, equipped with a vessel holder similar to a 48-well plate, was used. The increased throughput of this microcalorimeter makes it valuable for biomedical and pharmaceutical applications. Our results show that the sensitivity of the instrument allows the detection of 3 × 10(4) bacteria per vial. Growth of P. mirabilis in Luria Broth medium was detected between 2 and 9 h with decreasing inoculum. The culture released 2.1J with a maximum thermal power of 76 μW. The growth rate calculated using calorimetric and spectrophotometric data were 0.60 and 0.57 h(-1) , respectively. Additional insight on protease activities of P. mirabilis matching the last peak in heat production could be gathered as well. Growth of tumor microtissues releasing a maximum thermal power of 2.1 μW was also monitored and corresponds to a diameter increase of the microtissues from ca. 100 to 428 μm. This opens new research avenues in cancer research, diagnostics, and development of new antitumor drugs. For parasitic worms, the technique allows assessment of parasite survival using motor and metabolic activities even with a single worm.

  9. A hybrid stochastic-deterministic computational model accurately describes spatial dynamics and virus diffusion in HIV-1 growth competition assay.

    Science.gov (United States)

    Immonen, Taina; Gibson, Richard; Leitner, Thomas; Miller, Melanie A; Arts, Eric J; Somersalo, Erkki; Calvetti, Daniela

    2012-11-01

    We present a new hybrid stochastic-deterministic, spatially distributed computational model to simulate growth competition assays on a relatively immobile monolayer of peripheral blood mononuclear cells (PBMCs), commonly used for determining ex vivo fitness of human immunodeficiency virus type-1 (HIV-1). The novel features of our approach include incorporation of viral diffusion through a deterministic diffusion model while simulating cellular dynamics via a stochastic Markov chain model. The model accounts for multiple infections of target cells, CD4-downregulation, and the delay between the infection of a cell and the production of new virus particles. The minimum threshold level of infection induced by a virus inoculum is determined via a series of dilution experiments, and is used to determine the probability of infection of a susceptible cell as a function of local virus density. We illustrate how this model can be used for estimating the distribution of cells infected by either a single virus type or two competing viruses. Our model captures experimentally observed variation in the fitness difference between two virus strains, and suggests a way to minimize variation and dual infection in experiments.

  10. Evaluation of two commercial assays for the detection of Chlamydophila abortus antibodies.

    Science.gov (United States)

    Vretou, E; Radouani, F; Psarrou, E; Kritikos, I; Xylouri, E; Mangana, O

    2007-07-20

    Two commercial enzyme-linked immunosorbent assays (ELISA), the CHEKIT-CHLAMYDIA which uses inactivated Chlamydophila psittaci antigen, and the Chlamydophila abortus ELISA produced by the Institut Pourquier which uses a recombinant fragment of the 80-90 kDa protein, were evaluated with the objective to determine whether the new ELISAs would perform as improved alternatives to the complement fixation test (CFT) for the serological diagnosis of ovine enzootic abortion (OEA). The results were compared to those obtained by the CFT and the competitive ELISA (cELISA). The tests were assessed with a panel of 17 serum samples from specific pathogen-free (SPF) lambs experimentally infected with various subtypes of Chlamydophila pecorum, with sera from 45 C. abortus-infected pregnant sheep and from 54 sheep free of OEA. The C. abortus ELISA was identified as being more specific and sensitive than the other tests. The 4 assays were evaluated further with 254 sera from flocks with documented OEA, from flocks with no history of abortion and from animals after abortion of unknown cause. The C. abortus ELISA by the Institut Pourquier identified less OEA-positive sera than the other assays though it identified correctly 9 of 10 OEA-positive flocks. The basis of the discordant results is discussed.

  11. Significance of enzyme linked immunosorbent assay (ELISA) for antibodies to double stranded and single stranded DNA in patients with lupus nephritis: correlation with severity of renal histology.

    Science.gov (United States)

    Okamura, M; Kanayama, Y; Amastu, K; Negoro, N; Kohda, S; Takeda, T; Inoue, T

    1993-01-01

    The correlation between renal histology and class specific (IgG and IgM) antibodies to double stranded DNA (dsDNA) and single stranded DNA (ssDNA) was studied by enzyme linked immunosorbent assay (ELISA) in 40 untreated patients with systemic lupus erythematosus (SLE). The levels of IgG antibodies to dsDNA were significantly higher in patients with World Health Organisation class IV nephritis than in those with class I, class II, or class III nephritis. IgG antibodies to ssDNA were higher in patients with class IV than in those with class II nephritis. IgG antibodies to dsDNA showed a close correlation with the histological activity score and the amount of electron dense deposit. IgG antibodies to ssDNA showed only a weak correlation with the renal histological activity score. IgM antibodies to dsDNA and IgM antibodies to ssDNA were not correlated with renal histological features. Patients with moderate to severe nephritis had a lower ratio of IgM antibodies to dsDNA to IgG antibodies to dsDNA than those with mild nephritis. These results indicate that the measurement of IgG antibodies to dsDNA is predictive in evaluating renal histological activity in patients with SLE.

  12. Nutriproteomic Analysis of Hwangmaemok-Induced Antiangiogenic Effect Using Antibody-Arrayed Protein Chip Assay.

    Science.gov (United States)

    Park, Yu Mi; Kim, Min-A; Jung, Hee Tae; Kang, Hwa Jeong; Yoo, Hwa-Seung; Kang, In-Cheol

    2017-06-01

    We investigated the antiangiogenic effects of Lindera obtusiloba Blume (Hwangmaemok, HMM), which is a plant in the Lauraceae family that is commonly used to treat colds and gastritis. Moreover, given that a recent study reported the inhibitory effects of HMM extract on cancer metastasis, we hypothesized that HMM extract might possess and antiangiogenic function. Thus, this study was conducted to investigate the effects of HMM extract on endothelial cell proliferation, migration, and neovascularization in chick chorioallantoic membrane (CAM), and investigated the molecular mechanism of antiangiogenesis using a ProteoChip-based proteomics technology. To examine the effects of HMM extracts on endothelial cell proliferation and migration, we conducted basic fibroblast growth factor (bFGF)-induced human umbilical vein endothelial cell (HUVEC) proliferation and migration. To assess the molecular mechanism of the antiangiogenic effects of HMM extract, a ProteoChip-based forwarded phase antibody array was employed to identify the differential expression of cell cycle proteins in HMM-treated HUVECs. HMM extract inhibited bFGF-induced HUVEC proliferation and migration in a dose-dependent manner and CAM angiogenesis. The ProteoChip-based antibody microarray data showed upregulation of Nibrin/NBS1 and downregulation of Plk-1 and Cyclin E, which are involved in cell division and controlling the cell cycle in bFGF-induced HUVECs. These data suggest that HMM may be a potent antitumor medicinal herb. The present study demonstrates that the antiangiogenic effect of HMM may be due to suppression of endothelial cell proliferation and migration. Taken together, these results emphasize the potential to use HMM extract as a potent angiogenesis inhibitor to treat cancer.

  13. Comparison of antibody assays for detection of autoantibodies to Ro 52, Ro 60 and La associated with primary Sjögren's syndrome.

    Science.gov (United States)

    Trier, Nicole Hartwig; Nielsen, Inger Ødum; Friis, Tina; Houen, Gunnar; Theander, Elke

    2016-06-01

    Anti-Ro(52/60) and anti-La constitute the hallmark autoantibodies in primary Sjögren's syndrome, being present in 40-70% of sera. Several anti-Ro/La assays exist, but antibody detection appears to be assay-specific, thus the aim of this study was to compare several anti-Ro/La assays. In total, 96 sera from individuals with primary Sjögren's syndrome and 114 healthy controls were tested for anti-Ro 52/60 and anti-La in 17 immunoassays. Especially the immunoassays used for detection of anti-Ro 52 differed in their sensitivity (48-79%), while only small differences in sensitivities were observed for the anti-Ro 60 (69-77%) anti-La (39-44%) assays. Concordances of 65%, 79% and 73% for the anti-Ro 52, anti-Ro 60 and anti-La assays were found, respectively. The majority of the assays yielded high specificities, primarily ranging from 97 to 100%, except from a single anti-Ro 60 assay, which yielded a specificity of 79%. Occasionally, reactivity levels were increased in a few assays, indicating that false-positive results can be obtained when applying assays of reduced specificity. In general, the commercial assays appeared to perform better than the in-house analyses. When correcting the in-house assays for background reactivity, sensitivities were reduced by approximately 7%, 17%, and 19% for anti-Ro 52, anti-Ro 60 and anti-La assays, respectively, illustrating the pitfalls when applying immunoassays for detection of autoantibodies, which in theory may apply to commercial assays as well. Finally, increased total sensitivities were obtained when combining assays. These studies contribute to clarify the clinical utility of immunoassays for detection of autoantibodies of Ro 52, Ro 60 and La and illustrate that the most efficient strategy to maximize antibody sensitivity is to combine several assays.

  14. Preparation of a specific monoclonal antibody to asiaticoside for the development of an enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Juengwatanatrakul, Thaweesak; Sritularak, Boonchoo; Amornnopparattanakul, Paveena; Tassanawat, Patcharin; Putalun, Waraporn; Tanaka, Hiroyuki; Morimoto, Satoshi

    2011-03-01

    Asiaticoside (AS), the major active component of Centella asiatica (L.) Urban, is used as a memory enhancer and for wound healing. We have successfully prepared monoclonal antibodies (MAbs) against AS, and developed an enzyme-linked immunosorbent assay (ELISA) system for its determination. AS was conjugated to the carrier protein bovine serum albumin (BSA), which acted as an immunogen. In order to confirm its immunogenicity, the ratio of hapten in the AS-BSA conjugate was determined by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). After immunization, hybridomas secreting MAbs against AS were produced by fusing splenocytes with the mouse myeloma cell line, SP2/0-Ag14. After the screening, anti-asiaticoside MAb 2B4 was obtained. Weak cross-reactivities occurred with madecassoside (7.08%), but no cross-reactivities were observed with other related triterpenoid glycosides (<0.01%). The assay was suitable for quantitating AS in the range of 0.78 to 50 µg mL(-1). A good correlation of AS concentrations in crude extracts of C. asiatica between ELISA and HPLC methods was obtained (r(2) = 0.999). The contents of AS in various cultivated C. asiatica samples were assayed by the newly established ELISA. The recovery rates of AS in the samples were in the range of 95-103% with coefficients of variation of <10%. The intra- and inter-assay variations were 3.9 and 4.5%, respectively. The ELISA method described should prove useful as an analytical tool for quality control and standardization of medicinal plants and pharmaceutical products containing AS.

  15. Rapid and accurate detection of Mycobacterium tuberculosis in sputum samples by Cepheid Xpert MTB/RIF assay--a clinical validation study.

    Directory of Open Access Journals (Sweden)

    Andrea Rachow

    Full Text Available BACKGROUND: A crucial impediment to global tuberculosis control is the lack of an accurate, rapid diagnostic test for detection of patients with active TB. A new, rapid diagnostic method, (Cepheid Xpert MTB/RIF Assay, is an automated sample preparation and real-time PCR instrument, which was shown to have good potential as an alternative to current reference standard sputum microscopy and culture. METHODS: We performed a clinical validation study on diagnostic accuracy of the Xpert MTB/RIF Assay in a TB and HIV endemic setting. Sputum samples from 292 consecutively enrolled adults from Mbeya, Tanzania, with suspected TB were subject to analysis by the Xpert MTB/RIF Assay. The diagnostic performance of Xpert MTB/RIF Assay was compared to standard sputum smear microscopy and culture. Confirmed Mycobacterium tuberculosis in a positive culture was used as a reference standard for TB diagnosis. RESULTS: Xpert MTB/RIF Assay achieved 88.4% (95%CI = 78.4% to 94.9% sensitivity among patients with a positive culture and 99% (95%CI = 94.7% to 100.0% specificity in patients who had no TB. HIV status did not affect test performance in 172 HIV-infected patients (58.9% of all participants. Seven additional cases (9.1% of 77 were detected by Xpert MTB/RIF Assay among the group of patients with clinical TB who were culture negative. Within 45 sputum samples which grew non-tuberculous mycobacteria the assay's specificity was 97.8% (95%CI = 88.2% to 99.9%. CONCLUSIONS: The Xpert MTB/RIF Assay is a highly sensitive, specific and rapid method for diagnosing TB which has potential to complement the current reference standard of TB diagnostics and increase its overall sensitivity. Its usefulness in detecting sputum smear and culture negative patients needs further study. Further evaluation in high burden TB and HIV areas under programmatic health care settings to ascertain applicability, cost-effectiveness, robustness and local acceptance are required.

  16. Anti-citrullinated protein antibodies in the diagnosis of rheumatoid arthritis (RA): diagnostic performance of automated anti-CCP-2 and anti-CCP-3 antibodies assays.

    Science.gov (United States)

    Vos, Ine; Van Mol, Christof; Trouw, Leendert A; Mahler, Michael; Bakker, Jaap A; Van Offel, Jan; De Clerck, Luc; Huizinga, Tom W

    2017-07-01

    This study compares the diagnostic performance of a second generation anti-cyclic citrullinated peptide antibody (CCP2) with a third generation anti-CCP antibodies assay (CCP3), as well as the combination of both tests. Serum samples of 127 patients were analyzed. IgG anti-CCP 2 and IgM rheumatoid factor were determined by EliA™ technique on a Phadia 250 instrument (Thermo Fisher Scientific), anti-CCP3 by the Quanta Flash™ anti-CCP3 IgG kit, BIO-FLASH Rapid Response Chemiluminscence Analyzer (INOVA Diagnostics). Diagnostic performance was compared using ROC-curves, sensitivity, specificity, likelihood ratios, and predictive values. Logistic regressions were used to investigate whether using both tests (anti-CCP2 and anti-CCP3) gives a better prediction of rheumatoid arthritis. At the manufacturer's cut-offs sensitivity and specificity were 79.4 and 61.0% for CCP3 and 80.9 and 69.5% for CCP2. No significant differences could be observed regarding the areas under the curve (AUC) of both ROC-curves. The optimal cut-off point for CCP2 was 10.5 U/ml (sensitivity of 75.0% and specificity of 80.0%) and 5.6 U/ml for CCP3 (sensitivity of 86.9% and specificity of 61.0%). Binary logistic regressions indicated that the likelihood of having rheumatoid arthritis (RA) is significantly higher when testing positive on both CCP2 and CCP3 compared to CCP2 or CCP3 alone. In our cohort, comparable performance was found between the two CCP assays. Positivity for both CCP2 and CCP3 resulted in the most specific identification of RA patients. In patients with joint complaints suspected of having RA and with a weakly positive CCP 2 (≥7 and ≤16 U/ml) CCP3 testing could be of additive value for diagnosing RA.

  17. Development and application of triple antibody sandwich enzyme-linked immunosorbent assays for begomovirus detection using monoclonal antibodies against Tomato yellow leaf curl Thailand virus.

    Science.gov (United States)

    Seepiban, Channarong; Charoenvilaisiri, Saengsoon; Warin, Nuchnard; Bhunchoth, Anjana; Phironrit, Namthip; Phuangrat, Bencharong; Chatchawankanphanich, Orawan; Attathom, Supat; Gajanandana, Oraprapai

    2017-05-30

    Tomato yellow leaf curl Thailand virus, TYLCTHV, is a begomovirus that causes severe losses of tomato crops in Thailand as well as several countries in Southeast and East Asia. The development of monoclonal antibodies (MAbs) and serological methods for detecting TYLCTHV is essential for epidemiological studies and screening for virus-resistant cultivars. The recombinant coat protein (CP) of TYLCTHV was expressed in Escherichia coli and used to generate MAbs against TYLCTHV through hybridoma technology. The MAbs were characterized and optimized to develop triple antibody sandwich enzyme-linked immunosorbent assays (TAS-ELISAs) for begomovirus detection. The efficiency of TAS-ELISAs for begomovirus detection was evaluated with tomato, pepper, eggplant, okra and cucurbit plants collected from several provinces in Thailand. Molecular identification of begomoviruses in these samples was also performed through PCR and DNA sequence analysis of the CP gene. Two MAbs (M1 and D2) were generated and used to develop TAS-ELISAs for begomovirus detection. The results of begomovirus detection in 147 field samples indicated that MAb M1 reacted with 2 begomovirus species, TYLCTHV and Tobacco leaf curl Yunnan virus (TbLCYnV), whereas MAb D2 reacted with 4 begomovirus species, TYLCTHV, TbLCYnV, Tomato leaf curl New Delhi virus (ToLCNDV) and Squash leaf curl China virus (SLCCNV). Phylogenetic analyses of CP amino acid sequences from these begomoviruses revealed that the CP sequences of begomoviruses recognized by the narrow-spectrum MAb M1 were highly conserved, sharing 93% identity with each other but only 72-81% identity with MAb M1-negative begomoviruses. The CP sequences of begomoviruses recognized by the broad-spectrum MAb D2 demonstrated a wider range of amino acid sequence identity, sharing 78-96% identity with each other and 72-91% identity with those that were not detected by MAb D2. TAS-ELISAs using the narrow-specificity MAb M1 proved highly efficient for the detection of

  18. Evaluation of an egg yolk enzyme-linked immunosorbent assay antibody test and its use to assess the prevalence of Mycoplasma gallisepticum infection in laying hens in Italy

    Directory of Open Access Journals (Sweden)

    Marco Tamba

    2010-01-01

    Full Text Available The prevalence of Mycoplasma gallisepticum infection in commercial layers was established by the presence of antibodies in eggs. Saline-extracted yolks were used with a commercial enzyme-linked immunosorbent assay kit. For the prevalence study, yolks from 30 eggs were obtained from each of 66 flocks coming from 36 layer farms. The prevalence of egg antibodies to Mycoplasma gallisepticum was 33.3% in single-age farms and 77.8% in multi-age farms. In 27 flocks, antibody titers were compared with results obtained from blood samples taken in the same flock and in the same period and analyzed with the same kit. This study has confirmed that egg yolk enzyme-linked immunosorbent assay antibody test is a suitable and practical approach for assessing the flock prevalence of Mycoplasma gallisepticum infection in layer hens.

  19. Malignant monoblasts can function as effector cells in natural killer cell and antibody-dependent cellular cytotoxicity assays

    DEFF Research Database (Denmark)

    Hokland, P; Hokland, M; Ellegaard, J

    1981-01-01

    This is the first report describing natural killer (NK) and antibody-dependent cellular cytotoxicity (ADCC) of malignant monoblasts. Pure acute monoblastic leukemia was diagnosed in bone marrow aspirations from two patients by use of conventional cytochemical methods as well as multiple immunologic...... techniques including detection of ALL antigens and terminal transferase. The malignant cells were subsequently found to be potent effectors in NK and ADCC assays. Addition of partially purified alpha-interferon to the in vitro cultures was found to have an enhancing effect on NK activity, whereas...... no modulation was seen in ADCC. These findings are discussed in the light of our present knowledge of lymphoid NK cells. Udgivelsesdato: 1981-May...

  20. A novel monoclonal antibody-based immunoenzymatic assay for epidemiological surveillance of the vector snails of Fasciola hepatica (Trematoda: Digenea).

    Science.gov (United States)

    Alba, Annia; Hernández, Hilda M; Marcet, Ricardo; Vázquez, Antonio A; Figueredo, Mabel; Sánchez, Jorge; Otero, Oscar; Sarracent, Jorge

    2015-02-01

    Fasciolosis is a globally distributed snail-borne disease which requires economic consideration due to its enormous impact on veterinary medicine. During recent decades, this parasitosis has also shown increasing prevalence in human populations worldwide. The dissemination and successful transmission of fasciolosis ultimately depends on the existence of susceptible snails that act as intermediate hosts. Therefore, to accomplish effective control of this disease, surveillance and detection of the infected intermediate host would be essential. The screening of trematodes within snails using classical parasitological examination of the larvae can be unreliable (sensitivity and specificity vary depending on the time of infection and the experience of the observer) and relatively costly when using molecular biological methods during large-scale monitoring. Here we propose a novel monoclonal antibody-based immunoenzymatic assay to detect ongoing Fasciola hepatica infection in lymnaeid snails. Anti-F. hepatica rediae mouse monoclonal antibodies were generated and used to develop a double monoclonal antibody-based ELISA for parasite detection. Fasciola hepatica-infected and uninfected laboratory-reared Galba cubensis and Pseudosuccinea columella were used for assessment of the developed ELISA. Experimentally infected snails were dissected and examined for parasite larvae as the "gold standard" method. Sensitivity results were 100% for both snail species, while specificity was 98% for G. cubensis and 100% for P. columella. No cross-reactivity was detected in lymnaeids infected with Trichobilharzia sp. or Cotylophoron sp. The ELISA enabled detection of the infection from day 8 p.i. in G. cubensis while in P. columella it was noted as early as day 4. To our knowledge no previous immunoassays have been reported to detect helminth-infected snails and the developed sandwich ELISA method is therefore suggested for infection status validation in natural populations of lymnaeid

  1. Production of monoclonal antibodies against GPCR using cell-free synthesized GPCR antigen and biotinylated liposome-based interaction assay.

    Science.gov (United States)

    Takeda, Hiroyuki; Ogasawara, Tomio; Ozawa, Tatsuhiko; Muraguchi, Atsushi; Jih, Pei-Ju; Morishita, Ryo; Uchigashima, Motokazu; Watanabe, Masahiko; Fujimoto, Toyoshi; Iwasaki, Takahiro; Endo, Yaeta; Sawasaki, Tatsuya

    2015-06-10

    G-protein-coupled receptors (GPCRs) are one of the most important drug targets, and anti-GPCR monoclonal antibody (mAb) is an essential tool for functional analysis of GPCRs. However, it is very difficult to develop GPCR-specific mAbs due to difficulties in production of recombinant GPCR antigens, and lack of efficient mAb screening method. Here we describe a novel approach for the production of mAbs against GPCR using two original methods, bilayer-dialysis method and biotinylated liposome-based interaction assay (BiLIA), both of which are developed using wheat cell-free protein synthesis system and liposome technology. Using bilayer-dialysis method, various GPCRs were successfully synthesized with quality and quantity sufficient for immunization. For selection of specific mAb, we designed BiLIA that detects interaction between antibody and membrane protein on liposome. BiLIA prevented denaturation of GPCR, and then preferably selected conformation-sensitive antibodies. Using this approach, we successfully obtained mAbs against DRD1, GHSR, PTGER1 and T1R1. With respect to DRD1 mAb, 36 mouse mAbs and 6 rabbit mAbs were obtained which specifically recognized native DRD1 with high affinity. Among them, half of the mAbs were conformation-sensitive mAb, and two mAbs recognized extracellular loop 2 of DRD1. These results indicated that this approach is useful for GPCR mAb production.

  2. Comparison of seven commercial enzyme-linked immunosorbent assays for the detection of anti-diphtheria toxin antibodies.

    Science.gov (United States)

    Zasada, A A; Rastawicki, W; Śmietańska, K; Rokosz, N; Jagielski, M

    2013-07-01

    Determination of immune status of patients to diphtheria toxin is based mainly on the results of commercially available ELISA kits. The aim of the present study was to compare the results obtained by ELISAs from seven different manufacturers: Mikrogen, Immunolab, Sekisui Virotech, NovaTec, Virion\\Serion, IBL International and Euroimmun. All assays were performed according to the manufacturers' instructions. The concentrations of the anti-diphtheria toxin antibodies in 72 serum samples were calculated on the basis of curves constructed from standards supplied by manufacturers and the new reference material-International Standard for Diphtheria Antitoxin (10/262). The repeatability and reproducibility of all the ELISA kits tested were good. Number of sera with concentrations of the anti-diphtheria toxin antibodies below the WHO-recommended level of protection (0.1 IU/ml) were dependent on the ELISA used: Mikrogen, 20/72 samples (27.7%); Immunolab, 11/72 samples (15.3%); Sekisui Virotech, 0/72 samples (0%); NovaTec 18/72 samples (25.0%); Serion 12/72 samples (16.7%); IBL International, 7/72 samples (9.7 %); and Euroimmun, 17/72 samples (23.6%). However, the results obtained in particular ELISAs, with the exception of Sekisui Virotech, were much more consistent when the concentrations of the anti-diphtheria toxin antibodies in 72 sera measured by using curves constructed from the International Standard 10/262. The data obtained clearly demonstrated that manufacturer-dependent differences between anti-diphtheria IgG ELISA kits exist. The differences in recommendations accepted by the individual manufacturers together with differences shown in our studies in sensitivity greatly affect the clinical interpretation of results.

  3. Comparison of enzyme linked immunosorbent assay (ELISA with indirect immunofluorescence for detection of anti-nuclear antibody

    Directory of Open Access Journals (Sweden)

    G.L.S. Sumanth Kumar

    2014-10-01

    Full Text Available Background: Detection of antinuclear antibody (ANA is used as one of the diagnostic criteria for autoimmune rheumatic diseases (ARD. Both indirect immunofluorescence (IIF and enzyme linked immunosorbant assay (ELISA methods are used for this purpose. However, there are lack of data comparing these two tests from India. Methods: We prospectively studed 294 patients clinically suspected to be having ARD between April 2012 and September 2013. They were tested for ANA by IIF and ELISA methods. Representative samples positive by both the tests were processed again by a line immunoassay test to detect the specific antinuclear antibodies. Considering the IIF results as the ‘gold standard’, the utility of ELISA for ANA detection was analyzed. Results: Of the 294 samples processed, 181 (61.5% were from female patients. By IIF 30% of samples in males and 40.3% sample in females tested positive. We found ELISA to have a poor sensitivity (45.8% but good specificity (99.5%. The positive predictive value for ELISA were 98% and negative predictive value 76.2% respectively. Forty four samples positive by both IIF and ELISA were tested by Western blot to detect individual autoantibodies. Of these, only 24 samples showed the presence of one or more bands, while the remaining 20 (45.4% were negative by line immunoassay. In our study anti-nuclear ribonucleoprotein/Smith was the most common ANA detected. Conclusions: The poor sensitivity raises concerns regarding the practice of initial screening for ANA by ELISA

  4. 抗核抗体筛查试验与特异性抗体确认试验的相关性研究%Correlation between screening assay of antinuclear antibody and confirmatory assay of specific antibody

    Institute of Scientific and Technical Information of China (English)

    周仁芳; 胡朝军; 张蜀澜; 白伊娜; 宋宁; 李丽君; 李永哲

    2009-01-01

    Objective To investigate the correlation between screening assay of antinuclear antibody ( ANA ) and confirmatory assay of specific antibody. Methods Five hundred clinical patients' serum samples were detected by indirect immunofluorescence ( I1F) for screening assay of ANAs and line immunoassay ( LIA) for confirmatory assay of specific ANAs. According to the results of IIF-ANA and LIA-ANAs, 500 samples were divided into 4 groups; IIF-ANA ~+/LIA-ANAs~+ group, IIF-ANA~+/LIA-ANAs~-group, IIF-ANA~-/LIA-ANAs~+ group and IIF-ANA~-LIA-ANAs~- group. The samples in IIF-ANA~-VLIA-ANAs~+ group were collected and rechecked by ELISA and DID for detection of specific ANAs. Results Five hundred clinical samples were identified including 247 cases of IIF-ANA~+/LJA-ANAs~+86 cases of IIF-ANA ~+/LIA-ANAs~- , 152 cases of IIF-ANA~-/LIA-ANAs~- and 15 cases of IIF-ANA~- /LIA-ANAs~+, In IIF-ANA ~+/LIA-ANAs~+ group, 48. 2% ,23. 9% and 27. 9% patients had the titre of IIF-ANA 1:1 280, 1: 80-1:160 and 1:320-1:640. Fifteen cases of LJA-ANAs~+ were identified in 167 cases of HF-ANA(9. 0% ). Among 15 cases of IIF-ANA~-/LIA-ANAs~+ 11 positive cases were identified as anti-SSA and anti-Ro52 positive, which were rechecked by ELISA and DID, and the results were consistent with the prior detection. Other positive cases were identified including 1 case of anti-Histone, 1 case of anti-Scl-70, 1 case of anti-Jo-1 and 1 case of anti-AMA-M2. The positive consistent rates between LJA-ANAs and ELJSA, DID were 100% , 69% respectively. And 8 cases of IIF-ANA~-/LJA-ANAs~+ patients were diagnosed with autoimmune disease after clinical data analysis. Among 86 cases of IIF-ANA ~+ /LJA-ANAs~- , 50.0% and 36.1% patients had the titre of 1: 80-1: 160 and homogeneous fluorescence pattern respectively. There was a significant difference in IIF-ANA~+/LIA-ANAs~- group and IIF-ANA ~+/LIA-ANAs~+ (χ~2 =20.47,12.42, P<0. 05). Conclusions It is recommend that specific antinuclear antibodies can be used once screening

  5. An integrated microfluidic system for measurement of glycated hemoglobin levels by using an aptamer-antibody assay on magnetic beads.

    Science.gov (United States)

    Chang, Ko-Wei; Li, Jinglun; Yang, Ching-Hsuan; Shiesh, Shu-Chu; Lee, Gwo-Bin

    2015-06-15

    Blood glycated hemoglobin (HbA1c), reflecting the average blood glucose level in the proceeding 2-3 months, is recommended for screening/diagnosing and patient management of diabetes. However, accurate measurement of the HbA1c level at the point of care is hampered by costly, large-scale instruments (such as high-performance liquid chromatography) or reagent instability of classical immunologic methods, which involve antibody-based immunoturbidimetry. In this work, an integrated microfluidic system using aptamer-based testing to measure HbA1c in blood samples is therefore presented. This measuring system used nucleic-acid aptamers that exhibited high sensitivity and high specificity for hemoglobin and HbA1c to perform a stable and robust testing. The compact microfluidic system consumed less samples and reagents and significantly shortened the detection time. Combining the advantages of microfluidics and aptamers, this integrated microsystem presents a promising tool for accurate and point-of-case HbA1c detection. To demonstrate its clinical utility, whole blood samples with clinically-relevant concentrations of HbA1c and Hb were automatically measured on the integrated microfluidic system. Experimental data showed that the developed aptamer-based microfluidic system is capable of detecting HbA1c and Hb with a good linear response. The entire process was completed within 25 min. The aptamer-antibody on-chip sandwich immunoassay may be further refined to allow diabetes screening and diagnosis at lower cost and earlier phase to minimize the risk of diabetic complications.

  6. SPECT assay of radiolabeled monoclonal antibodies. Progress report, September 1, 1992--August 24, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Jaszczak, R.J.

    1993-08-20

    The overall goal of this project is to improve the effectiveness of single photon emission computed tomography (SPECT) to image and quantify radiolabeled monoclonal antibodies. During the past year, we have made significant progress toward this goal, and this report summarizes that work. Our efforts have been mainly directed along three fronts. First, we have developed and tested new reconstruction methods including three-dimensional iterative algorithms that model non-uniform attenuation and distance-dependent detector response. Both fan beam and parallel beam collimator geometries have been modeled and novel ways of improving the efficiency of the computationally intensive methods have been introduced. Second, an ultra-high resolution, small field-of-view pinhole collimator has been constructed and evaluated. Reconstructed spatial resolution of 1 to 3 mm (FWHM) has been achieved in phantom scans with a useful field-of-view of 9 to 10 cm. Finally, we have investigated the ability of SPECT to image and quantify astatine-211 distributions. Reconstructed images of phantom data demonstrated quantitative accuracy to within 10% with proper attenuation and scatter compensation.

  7. Bayesian Validation of the Indirect Immunofluorescence Assay and Its Superiority to the Enzyme-Linked Immunosorbent Assay and the Complement Fixation Test for Detecting Antibodies against Coxiella burnetii in Goat Serum.

    Science.gov (United States)

    Muleme, Michael; Stenos, John; Vincent, Gemma; Campbell, Angus; Graves, Stephen; Warner, Simone; Devlin, Joanne M; Nguyen, Chelsea; Stevenson, Mark A; Wilks, Colin R; Firestone, Simon M

    2016-06-01

    Although many studies have reported the indirect immunofluorescence assay (IFA) to be more sensitive in detection of antibodies to Coxiella burnetii than the complement fixation test (CFT), the diagnostic sensitivity (DSe) and diagnostic specificity (DSp) of the assay have not been previously established for use in ruminants. This study aimed to validate the IFA by describing the optimization, selection of cutoff titers, repeatability, and reliability as well as the DSe and DSp of the assay. Bayesian latent class analysis was used to estimate diagnostic specifications in comparison with the CFT and the enzyme-linked immunosorbent assay (ELISA). The optimal cutoff dilution for screening for IgG and IgM antibodies in goat serum using the IFA was estimated to be 1:160. The IFA had good repeatability (>96.9% for IgG, >78.0% for IgM), and there was almost perfect agreement (Cohen's kappa > 0.80 for IgG) between the readings reported by two technicians for samples tested for IgG antibodies. The IFA had a higher DSe (94.8%; 95% confidence interval [CI], 80.3, 99.6) for the detection of IgG antibodies against C. burnetii than the ELISA (70.1%; 95% CI, 52.7, 91.0) and the CFT (29.8%; 95% CI, 17.0, 44.8). All three tests were highly specific for goat IgG antibodies. The IFA also had a higher DSe (88.8%; 95% CI, 58.2, 99.5) for detection of IgM antibodies than the ELISA (71.7%; 95% CI, 46.3, 92.8). These results underscore the better suitability of the IFA than of the CFT and ELISA for detection of IgG and IgM antibodies in goat serum and possibly in serum from other ruminants.

  8. The enzyme-linked immunosorbent assay (ELISA) as a serological test for detecting antibodies against Leptospira interrogans serovar hardjo in sheep.

    Science.gov (United States)

    Adler, B; Faine, S; Gordon, L M

    1981-09-01

    The enzyme-liked immunosorbent assay (ELISA) was compared with the standard microscopic agglutination test (MAT) as a method for detecting antibodies against Leptospira interrogans serovar hardjo in sheep. Peak antibody levels detected by the 2 tests occurred at different times following experimental infection of sheep. In serums from flocks of sheep with naturally acquired infection there was a 95% correlation between MAT and ELISA with respect to the presence or absence of antibody to serovar hardjo, although the levels of correlation of the titres of the 2 tests was low. The 2 tests appeared to measure different antigen-antibody systems. The ELISA would be a useful test for screening large numbers of serums for antibodies to L. interrogans serovar hardjo.

  9. Comparison of a Monoclonal Antibody-Blocking Enzyme-Linked Immunoassay and a Strip Immunoblot Assay for Identifying Type-Specific Herpes Simplex Virus Type 2 Serological Responses

    OpenAIRE

    van Doornum, G. J. J.; Slomka, M.J.; Buimer, M; Groen, J.; van den Hoek, J.A.R.; Cairo, I.; Vyse, A.; Brown, D. W G

    2000-01-01

    Detection of herpes simplex virus type 2 (HSV-2)-specific antibodies by a monoclonal antibody (MAb)-blocking enzyme-linked immunoassay (EIA) was compared with detection by a strip immunoblot assay (SIA) in a sexually transmitted disease (STD) clinic population. The study population consisted of 1,683 genitourinary medicine clinic attendees (582 women and 1,101 men). Sera were tested for the presence of HSV-2 antibody by use of the blocking EIA, in which binding of the MAb AP-1 to HSV-2 glycop...

  10. Allele Specific Locked Nucleic Acid Quantitative PCR (ASLNAqPCR): An Accurate and Cost-Effective Assay to Diagnose and Quantify KRAS and BRAF Mutation

    Science.gov (United States)

    Morandi, Luca; de Biase, Dario; Visani, Michela; Cesari, Valentina; De Maglio, Giovanna; Pizzolitto, Stefano; Pession, Annalisa; Tallini, Giovanni

    2012-01-01

    The use of tyrosine kinase inhibitors (TKIs) requires the testing for hot spot mutations of the molecular effectors downstream the membrane-bound tyrosine kinases since their wild type status is expected for response to TKI therapy. We report a novel assay that we have called Allele Specific Locked Nucleic Acid quantitative PCR (ASLNAqPCR). The assay uses LNA-modified allele specific primers and LNA-modified beacon probes to increase sensitivity, specificity and to accurately quantify mutations. We designed primers specific for codon 12/13 KRAS mutations and BRAF V600E, and validated the assay with 300 routine samples from a variety of sources, including cytology specimens. All were analyzed by ASLNAqPCR and Sanger sequencing. Discordant cases were pyrosequenced. ASLNAqPCR correctly identified BRAF and KRAS mutations in all discordant cases and all had a mutated/wild type DNA ratio below the analytical sensitivity of the Sanger method. ASLNAqPCR was 100% specific with greater accuracy, positive and negative predictive values compared with Sanger sequencing. The analytical sensitivity of ASLNAqPCR is 0.1%, allowing quantification of mutated DNA in small neoplastic cell clones. ASLNAqPCR can be performed in any laboratory with real-time PCR equipment, is very cost-effective and can easily be adapted to detect hot spot mutations in other oncogenes. PMID:22558339

  11. Specific, sensitive, and quantitative enzyme-linked immunosorbent assay for human immunoglobulin G antibodies to anthrax toxin protective antigen.

    Science.gov (United States)

    Quinn, Conrad P; Semenova, Vera A; Elie, Cheryl M; Romero-Steiner, Sandra; Greene, Carolyn; Li, Han; Stamey, Karen; Steward-Clark, Evelene; Schmidt, Daniel S; Mothershed, Elizabeth; Pruckler, Janet; Schwartz, Stephanie; Benson, Robert F; Helsel, Leta O; Holder, Patricia F; Johnson, Scott E; Kellum, Molly; Messmer, Trudy; Thacker, W Lanier; Besser, Lilah; Plikaytis, Brian D; Taylor, Thomas H; Freeman, Alison E; Wallace, Kelly J; Dull, Peter; Sejvar, Jim; Bruce, Erica; Moreno, Rosa; Schuchat, Anne; Lingappa, Jairam R; Martin, Sandra K; Walls, John; Bronsdon, Melinda; Carlone, George M; Bajani-Ari, Mary; Ashford, David A; Stephens, David S; Perkins, Bradley A

    2002-10-01

    The bioterrorism-associated human anthrax epidemic in the fall of 2001 highlighted the need for a sensitive, reproducible, and specific laboratory test for the confirmatory diagnosis of human anthrax. The Centers for Disease Control and Prevention developed, optimized, and rapidly qualified an enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) antibodies to Bacillus anthracis protective antigen (PA) in human serum. The qualified ELISA had a minimum detection limit of 0.06 micro g/mL, a reliable lower limit of detection of 0.09 micro g/mL, and a lower limit of quantification in undiluted serum specimens of 3.0 micro g/mL anti-PA IgG. The diagnostic sensitivity of the assay was 97.8%, and the diagnostic specificity was 97.6%. A competitive inhibition anti-PA IgG ELISA was also developed to enhance diagnostic specificity to 100%. The anti-PA ELISAs proved valuable for the confirmation of cases of cutaneous and inhalational anthrax and evaluation of patients in whom the diagnosis of anthrax was being considered.

  12. Evaluation of an indirect enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against Anaplasma phagocytophilum in sheep.

    Science.gov (United States)

    Woldehiwet, Z; Yavari, C

    2012-01-01

    An indirect enzyme-linked immunosorbent assay (ELISA) for detection of antibodies against Anaplasma phagocytophilum in ovine serum samples was evaluated. The assay used purified A. phagocytophilum grown in tick cell cultures as antigen. Serum samples were diluted 1 in 200 and binding was detected with anti-sheep IgG conjugated to horseradish peroxidase. All tests were carried out in the presence of positive and negative control samples. Optical density (OD) values obtained for each test sample at 490 nm were used to calculate percentage positivity (PP) of each sample based on the ratio of the OD of the test sample that of the positive reference sample. Known negative samples (n=69) obtained from uninfected sheep bred and maintained in a tick-free environment and subsequently shown to be susceptible to A. phagocytophilum were used to establish the cut-off point between negative and positive samples and to establish the specificity of the test. Serum samples obtained from 92 animals 14-21 days after infection were used to establish the sensitivity of the test. Using a cut-off point of 20PP (mean+2 standard deviations of the PP of 69 control samples) the test was shown to have a sensitivity of 84.8% and a specificity of 95.7%. Lowering the cut-off point to 15PP increased the sensitivity to 94.6%, but reduced the specificity to 92.8%.

  13. In vivo neutralization assays by monoclonal antibodies against white spot syndrome virus in crayfish (Cambarus proclarkii)

    Institute of Scientific and Technical Information of China (English)

    WANG Yinan; ZHAN Wenbin; XING Jing; JIANG Yousheng

    2008-01-01

    The neutralizing activities of eight monoclonal antibodies (MAbs) against white spot syndrome virus (WSSV) (2D2,2B2,1D2,1DS,1C2,4A1,6A4 and 6B4) were analyzed by in vivo experiments.Gills from WSSV-infected shrimp were homogenized and ten-fold serially diluted by PBS,and then incubated with MAbs (hybridoma culture supernatant),respectively.The mixture of WSSV and MAbs were injected into crayfish (Procambarus clarkii).Mter challenge,the death rates of crayfish were counted to determine the neutralizing activities of MAbs.At the same time,the mixture of myeloma culture supernatant and WSSV or PBS was served as positive or negative control,respectively.The results showed that,at each virus dilution,the mean time to death of the crayfish injected with MAb-treated virus was significantly longer than that in the positive control,though they all showed 100% mortality within 25 d,and meanwhile,few crayfish died in the negative control.Among the eight MAbs,2D2,2B2,1D2 and 1DS,especially the former two,delayed the mortality significantly,and 1C2,4Al and 6A4 delayed the mortality as well but not so efficiently,while MAb 6B4 was efficient only when the virus concentration increased.The results indicated that the anti-WSSV MAbs can neutralize WSSV in different virus dilutions.

  14. Surface plasmon resonance-based competition assay to assess the sera reactivity of variants of humanized antibodies.

    Science.gov (United States)

    Gonzales, Noreen R; Schuck, Peter; Schlom, Jeffrey; Kashmiri, Syed V S

    2002-10-15

    While clinical trials are the only way to evaluate the immunogenicity, in patients, of murine or genetically engineered humanized variants of a potentially therapeutic or diagnostic monoclonal antibody (MAb), ethical and logistical considerations of clinical trials do not permit the evaluation of variants of a given MAb that are generated to minimize its immunogenicity. The most promising variant could be identified by comparing the reactivities of the parental antibody (Ab) and its variants to the sera of patients containing anti-variable region (anti-VR) Abs to the administered parental Ab. We have developed a surface plasmon resonance (SPR) biosensor-based assay to monitor the binding of the sera anti-VR Abs to the parental Ab and the inhibition of this binding by the variants. SPR biosensors allow the real-time detection and monitoring of the binding between an immobilized protein and its soluble ligand without the need for prior purification and labeling of the mobile analyte. This new assay requires no radiolabeling, is relatively less time-consuming, and uses only small amounts of serum (5-20 microl of diluted serum) through a new microfluidic sample handling technique. To validate the assay, we have tested the relative reactivities of the CDR-grafted anti-carcinoma Ab, HuCC49, and its two variants, designated V5 and V10, to the sera of patients who were earlier administered radiolabeled murine CC49 in a clinical trial. A comparison of IC(50)s (the concentrations of the competitor Abs required for 50% inhibition of the binding of sera to immobilized HuCC49) showed that V5 and V10 were less reactive than HuCC49 to the three patients' sera tested. We have also demonstrated, for the first time, the specific detection and comparison of relative amounts of anti-VR Abs present in the sera of different patients without prior removal of anti-murine Fc Abs and/or circulating antigen. This may facilitate the rapid screening, for the presence of anti-VR Abs, of the

  15. Limits of diagnostic accuracy of anti-hepatitis C virus antibodies detection by ELISA and immunoblot assay.

    Science.gov (United States)

    Suslov, Anatoly P; Kuzin, Stanislav N; Golosova, Tatiana V; Shalunova, Nina V; Malyshev, Nikolai A; Sadikova, Natalia V; Vavilova, Lubov M; Somova, Anna V; Musina, Elena E; Ivanova, Maria V; Kipor, Tatiana T; Timonin, Igor M; Kuzina, Lubov E; Godkov, Mihail A; Bajenov, Alexei I; Nesterenko, Vladimir G

    2002-07-01

    When human sera samples are tested for anti-hepatitis C virus (HCV) antibodies using different ELISA kits as well as immunoblot assay kits discrepant results often occur. As a result the diagnostics of HCV infection in such sera remains unclear. The purpose of this investigation is to define the limits of HCV serodiagnostics. Overall 7 different test kits of domestic and foreign manufacturers were used for the sampled sera testing. Preliminary comparative study, using seroconversion panels PHV905, PHV907, PHV908 was performed and reference kit was chosen (Murex anti-HCV version 4) as the most sensitive kit on the base of this study results. Overall 1640 sera samples have been screened using different anti-HCV ELISA kits and 667 of them gave discrepant results in at least two kits. These sera were then tested using three anti-HCV ELISA kits (first set of 377 samples) or four anti-HCV ELISA kits (second set of 290 samples) at the conditions of reference laboratory. In the first set 17.2% samples remained discrepant and in the second set - 13.4%. "Discrepant" sera were further tested in RIBA 3.0 and INNO-LIA immunoblot confirmatory assays, but approximately 5-7% of them remained undetermined after all the tests. For the samples with signal-to-cutoff ratio higher than 3.0 high rate of result consistency by reference, ELISA routing and INNO-LIA immunoblot assay was observed. On the other hand the results of tests 27 "problematic" sera in RIBA 3.0 and INNO-LIA were consistent only in 55.5% cases. Analysis of the antigen spectrum reactive with antibodies in "problematic" sera, demonstrated predominance of Core, NS3 and NS4 antigens for sera, positive in RIBA 3.0 and Core and NS3 antigens for sera, positive in INNO-LIA. To overcome the problem of undetermined sera, methods based on other principles, as well as alternative criteria of HCV infection diagnostics are discussed.

  16. Confirmation of positive antibody screens by solid-phase red cell adherence assay using a tube technique method with polyethylene glycol enhancement.

    Science.gov (United States)

    Gammon, R R; Lake, M; Velasquez, N; Prichard, A

    2001-01-01

    Our blood bank routinely screens donors for antibodies using a solid-phase red cell adherence (SPRCA) assay. Positive results are then confirmed using a tube technique with polyethylene glycol (PEG) enhancement due to reported higher specificity than with SPRCA. Over a 5-month period, 49,084 donor serum or plasma samples were tested using the SPRCA assay. Further identification of positive samples was performed using a PEG enhancement method. Testing was performed with strict adherence to the manufacturers' inserts. Of 49,084 samples, 313 (0.64%) were positive by the SPRCA assay. Of these, 99 (31.6%) samples remained positive when tested with PEG enhancement. The remaining 214 (68.4%) were negative, giving specificity for the SPRCA assay of 99.6 percent (48,985/ 49,199). We report a high specificity for antibody screening using the SPRCA assay. However, it is cost effective to perform a confirmatory tube test with PEG enhancement because 214 SPRCA assay samples were interpreted as having a negative antibody screen, thus allowing the release of valuable blood components for transfusion.

  17. prevalence of anti-cyclic citrullinated peptide antibodies in patients ...

    African Journals Online (AJOL)

    2013-07-30

    Jul 30, 2013 ... accurate disease classification. Pathognomonic ... classification criteria for RA (3) include such parameters ... reliant on the history and examination findings, with ..... Anticitrullinated protein/peptide antibody assays in early ...

  18. Clinical relevance of anti-HLA antibodies detected by flow-cytometry bead-based assays--single-center experience.

    Science.gov (United States)

    Mihaylova, Anastassia; Baltadjieva, Daniela; Boneva, Petia; Ivanova, Milena; Penkova, Kalina; Marinova, Daniela; Mihailova, Snejina; Paskalev, Emil; Simeonov, Petar; Naumova, Elissaveta

    2006-10-01

    The purpose of this study was to define the incidence, dynamics, and profiles of anti-human leukocyte antigen antibodies (HLA-Abs) produced after kidney transplantation and their impact on graft outcome. A total of 72 first cadaver donor kidney recipients were prospectively monitored for the development of HLA-Abs using bead-based flow-cytometry assays (One Lambda FlowPRA tests). Sixteen recipients (22.2%) developed HLA-Abs after transplantation (class I, n = 7; class I+II, n = 6; class II, n = 3), in most cases (81.25%) within the first 2 weeks posttransplantation. A strong association between alloantibody presence and delayed graft function (Chi-square = 7.659, p < 0.01), acute rejection (Chi-square = 14.504, p < 0.001), chronic rejection (Chi-square = 12.84, p < 0.001), and graft loss (Chi-square = 20.283, p < 0.001) was found. Patients with higher alloantibody titers experienced acute rejections and even early graft loss, compared with those with lower titers for whom chronic rejections were more common. Immunologic complications occurred in recipients with both donor-specific and cross-reacting groups or non-donor-specific antibodies alone. A positive correlation (Pearson correlation, 0.245; p < 0.05) between HLA class I amino acid triplet incompatibility and alloantibody production was observed, mainly resulting from immunogenic triplotypes. Given the results obtained in this study, an alloantibody testing algorithm has been designed and implemented for routine monitoring and to define optimally the alloantibody reactivity in kidney transplant recipients.

  19. Evaluation of enzyme-linked immunosorbent assays based on monoclonal antibodies for the serology and antigen detection in canine parvovirus infections.

    NARCIS (Netherlands)

    G.F. Rimmelzwaan (Guus); N. Juntti; B. Klingeborn; J. Groen (Jan); F.G.C.M. Uytdehaag (Fons); A.D.M.E. Osterhaus (Albert)

    1990-01-01

    textabstractAn enzyme-linked immunosorbent assay (ELISA) system was developed for the detection of canine parvovirus (CPV) or CPV antigen in dog faeces and two other ELISA systems were developed for the detection of CPV-specific antibodies in dog sera. The ELISA's were based on the use of CPV-specif

  20. Development and validation of an indirect Enzyme-linked Immunosorbent Assay for the detection of antibodies against Schmallenberg virus in blood samples from ruminants

    NARCIS (Netherlands)

    Heijden, van der H.M.J.F.; Bouwstra, R.J.; Mars, M.H.; Poel, van der W.H.M.; Wellenberg, G.J.; Maanen, van C.

    2013-01-01

    To detect Schmallenberg virus (SBV) infections in ruminants and to perform SBV epidemiological studies a cost-effective serological test is required. For these purposes an indirect whole virus Enzyme-linked Immunosorbent Assay (ELISA) for detection of SBV specific antibodies in ruminant blood sample

  1. Comparison of the inhibition of urokinase-type plasminogen activator (u-PA) activity by monoclonal antibodies specific for u-PA as assessed by different assays

    NARCIS (Netherlands)

    Boheemen, P.A. van; Hoogen, N.M. van den; Koolwijk, N.

    1995-01-01

    Six murine monoclonal antibodies (MAbs) specific for urokinase-type plasminogen activator (u-PA) were tested for their ability to inhibit u-PA activity in three different assays with respect to amidolytic activity, plasminogen activation and fibrinolytic activity. Two of the MAbs were able to inhibi

  2. Development of a monoclonal antibody-based enzyme-linked immunosorbent assay to quantify soluble beta-glucans in oats and barley.

    Science.gov (United States)

    Rampitsch, Christof; Ames, Nancy; Storsley, Joanne; Marien, Lindsay

    2003-09-24

    A set of 31 murine monoclonal antibodies was produced against (1-->3,1-->4)beta-d-glucan from oats (Avena sativa L.) chemically cross-linked to keyhole limpet hemocyanin. Monoclonal antibodies were tested for their cross-reactivity to related and unrelated polysaccharides. The antibodies reacted strongly to unmodified beta-glucan from oats and barley (Hordeum vulgare L.) and to lichenan from Icelandic moss, a polysaccharide with a structure similar to that of beta-glucan but which is not encountered in cereals. Cross-reaction to other polysaccharides tested was minimal at physiological levels. An enzyme-linked immunosorbent assay (ELISA) that could routinely detect and quantify nanogram levels of soluble beta-glucan extracted from the flour of oats or barley was designed with one of these monoclonal antibodies. The beta-glucan extraction procedure from ground oat and barley samples and the ELISA were both optimized for reproducibility, accuracy, and throughput, and results were compared to values obtained from an established, commercially available enzyme-based assay. Correlations between the two assays were consistently high (r (2) > 0.9), indicating that the ELISA presented in this paper is a valuable alternative for assaying beta-glucan levels in cereals and cereal products, both routinely and in preparations in which beta-glucans are present in nanogram amounts. Development of the extraction procedure for ELISA is discussed.

  3. An Efficient Multiplex PCR-Based Assay as a Novel Tool for Accurate Inter-Serovar Discrimination of Salmonella Enteritidis, S. Pullorum/Gallinarum and S. Dublin

    Science.gov (United States)

    Xiong, Dan; Song, Li; Tao, Jing; Zheng, Huijuan; Zhou, Zihao; Geng, Shizhong; Pan, Zhiming; Jiao, Xinan

    2017-01-01

    Salmonella enterica serovars Enteritidis, Pullorum/Gallinarum, and Dublin are infectious pathogens causing serious problems for pig, chicken, and cattle production, respectively. Traditional serotyping for Salmonella is costly and labor-intensive. Here, we established a rapid multiplex PCR method to simultaneously identify three prevalent Salmonella serovars Enteritidis, Pullorum/Gallinarum, and Dublin individually for the first time. The multiplex PCR-based assay focuses on three genes tcpS, lygD, and flhB. Gene tcpS exists only in the three Salmonella serovars, and lygD exists only in S. Enteritidis, while a truncated region of flhB gene is only found in S. Pullorum/Gallinarum. The sensitivity and specificity of the multiplex PCR assay using three pairs of specific primers for these genes were evaluated. The results showed that this multiplex PCR method could accurately identify Salmonella Enteritidis, Pullorum/Gallinarum, and Dublin from eight non-Salmonella species and 27 Salmonella serovars. The least concentration of genomic DNA that could be detected was 58.5 pg/μL and the least number of cells was 100 CFU. Subsequently, this developed method was used to analyze clinical Salmonella isolates from one pig farm, one chicken farm, and one cattle farm. The results showed that blinded PCR testing of Salmonella isolates from the three farms were in concordance with the traditional serotyping tests, indicating the newly developed multiplex PCR system could be used as a novel tool to accurately distinguish the three specific Salmonella serovars individually, which is useful, especially in high-throughput screening. PMID:28360901

  4. [Comparative study on the assay for IgE antibodies specific for Chamaecyparis obtusa pollen between AlaSTAT and CAP-RAST].

    Science.gov (United States)

    Nohara, O; Imai, T; Saneyoshi, K; Endo, T; Nagakura, H; Ono, M; Moriyama, H

    1996-06-01

    Titers of IgE antibody specific for the pollen of Chamaecyparis obtusa (C. obtusa) were determined by AlaSTAT and CAP-RAST in 221 patients with Japanese cedar pollinosis. IgE antibody to C. obtusa tested positive by CAP-RAST at a higher rate (80.5%) than by AlaSTAT (52.6%). The results obtained from the two assays were compared with those from intradermal skin test. CAP-RAST had a higher sensitivity than that of AlaSTAT. Because the two methods showed no differences in the determination of IgE antibody specific for Cryptomeria japonica, the above differences between AlaSTAT and CAP-RAST are surmised to be ascribable to the differences of C. obtusa antigen used in the both assays.

  5. Enzyme-linked immunosorbent assay for detection of antibodies to the venereal disease research laboratory (VDRL) antigen in syphilis.

    Science.gov (United States)

    Pedersen, N S; Orum, O; Mouritsen, S

    1987-09-01

    An enzyme-linked immunosorbent assay (ELISA) for detection of immunoglobulin G (IgG) and IgM to cardiolipin, lecithin, and cholesterol (VDRL [Venereal Disease Research Laboratory] ELISA) is described. The specificity of the VDRL ELISA for IgG and IgM was 99.6 and 99.5%, respectively, with sera from 1,008 persons without syphilis. For a group of patients with false-positive results in traditional nontreponemal tests and for patients with autoimmune diseases, the VDRL ELISA for IgG had a higher specificity than the VDRL ELISA for IgM. The sensitivity for IgG and IgM with 118 sera from patients with untreated syphilis was 96.6 and 94.9%, respectively, which was equivalent to the sensitivities of the traditional nontreponemal tests. The performance of the VDRL ELISA was compared with that of an ELISA that uses cardiolipin as the antigen (cardiolipin ELISA). The VDRL ELISA was significantly more sensitive (P less than or equal to 0.01) than the cardiolipin ELISA with 25 sera from syphilis patients but was less sensitive (P less than or equal to 0.01) with 53 sera from patients with autoimmune diseases. The antibody reactivity in the VDRL ELISA could not be absorbed out by lecithin and cholesterol, and the sera from patients with syphilis did not react in an ELISA that uses cholesterol and lecithin as the antigen. This indicates that cholesterol and lecithin, although not antigenic by themselves, may change the structural form of the epitope on cardiolipin so that it becomes more recognizable for antibodies in syphilis and less recognizable for antibodies in autoimmune diseases. The results of the VDRL ELISA were expressed in percentages of the absorbance value of a positive control. The VDRL ELISA gave, without titration of sera, quantitative results that correlated with the quantitative results of the traditional nontreponemal tests obtained by titration. The VDRL ELISA will be well suited for large-scale testing for syphilis and may replace other nontreponemal tests.

  6. A real-time PCR assay for accurate quantification of the individual members of the Altered Schaedler Flora microbiota in gnotobiotic mice.

    Science.gov (United States)

    Gomes-Neto, João Carlos; Mantz, Sara; Held, Kyler; Sinha, Rohita; Segura Munoz, Rafael R; Schmaltz, Robert; Benson, Andrew K; Walter, Jens; Ramer-Tait, Amanda E

    2017-04-01

    Changes in the gastrointestinal microbial community are frequently associated with chronic diseases such as Inflammatory Bowel Diseases. However, understanding the relationship of any individual taxon within the community to host physiology is made complex due to the diversity and individuality of the gut microbiota. Defined microbial communities such as the Altered Schaedler Flora (ASF) help alleviate the challenges of a diverse microbiota by allowing one to interrogate the relationship between individual bacterial species and host responses. An important aspect of studying these relationships with defined microbial communities is the ability to measure the population abundance and dynamics of each member. Herein, we describe the development of an improved ASF species-specific and sensitive real-time quantitative polymerase chain reaction (qPCR) for use with SYBR Green chemistry to accurately assess individual ASF member abundance. This approach targets hypervariable regions V1 through V3 of the 16S rRNA gene of each ASF taxon to enhance assay specificity. We demonstrate the reproducibility, sensitivity and application of this new method by quantifying each ASF bacterium in two inbred mouse lines. We also used it to assess changes in ASF member abundance before and after acute antibiotic perturbation of the community as well as in mice fed two different diets. Additionally, we describe a nested PCR assay for the detection of lowly abundant ASF members. Altogether, this improved qPCR method will facilitate gnotobiotic research involving the ASF community by allowing for reproducible quantification of its members under various physiological conditions.

  7. Evaluation of five different antigens in enzyme-linked immunosorbent assay for the detection of avian pneumovirus antibodies.

    Science.gov (United States)

    Maherchandani, Sunil; Patnayak, Devi P; Muñoz-Zanzi, Claudia A; Lauer, Dale; Goyal, Sagar M

    2005-01-01

    Five different antigens were evaluated in enzyme-linked immunosorbent assay (ELISA) tests for the detection of avian pneumovirus (APV) antibodies. Two of the 5 antigens were prepared from recent APV isolates from Minnesota. The 2 older isolates were passage 63 of a strain currently used as a live, attenuated vaccine and a Colorado strain isolated for the first time in the United States and currently used in an ELISA test. The fifth antigen is based on an APV recombinant N-protein. Basic parameters and positive-negative threshold of the assays were established for all 5 antigens on the basis of data obtained by testing 46 known negative and 46 known positive serum samples. Subsequently, 449 field samples were tested by all 5 ELISAs. The optical density difference (ODD) was calculated by subtracting optical density of the sample in the negative antigen well from that in the positive antigen well. In the current ELISA test based on the Colorado strain, an ODD of 0.2 is considered to be the cutoff value to classify samples as negative or positive. In this study, however, use of different cutoffs, based on ODD of negative control plus 3 SD or values estimated from Receiver operating characteristic analysis, was considered to be more appropriate for the various antigens used. Overall person-to-person and day-to-day variability was found to be large for all tests using either ODD or sample to positive ratio to report results. In addition, results suggest that antigenicity of the APV isolates in the United States has not changed between 1997 and 2000.

  8. Characterization of the native and denatured herceptin by enzyme linked immunosorbent assay and quartz crystal microbalance using a high-affinity single chain fragment variable recombinant antibody.

    Science.gov (United States)

    Shang, Yuqin; Mernaugh, Ray; Zeng, Xiangqun

    2012-10-02

    Herceptin/Trastuzumab is a humanized IgG1κ light chain antibody used to treat some forms of breast cancer. A phage-displayed recombinant antibody library was used to obtain a single chain fragment variable (scFv, designated 2B4) to a linear synthetic peptide representing Herceptin's heavy chain CDR3. Enzyme linked immunosorbent assays (ELISAs) and piezoimmunosensor/quartz crystal microbalance (QCM) assays were used to characterize 2B4-binding activity to both native and heat denatured Herceptin. The 2B4 scFv specifically bound to heat denatured Herceptin in a concentration dependent manner over a wide (35-220.5 nM) dynamic range. Herceptin denatures and forms significant amounts of aggregates when heated. UV-vis characterization confirms that Herceptin forms aggregates as the temperature used to heat Herceptin increases. QCM affinity assay shows that binding stoichiometry between 2B4 scFv and Herceptin follows a 1:2 relationship proving that 2B4 scFv binds strongly to the dimers of heat denatured Herceptin aggregates and exhibits an affinity constant of 7.17 × 10(13) M(-2). The 2B4-based QCM assay was more sensitive than the corresponding ELISA. Combining QCM with ELISA can be used to more fully characterize nonspecific binding events in assays. The potential theoretical and clinical implications of these results and the advantages of the use of QCM to characterize human therapeutic antibodies in samples are also discussed.

  9. Determination of anti-endomysium IgA antibodies in the diagnosis of celiac disease: Comparison of a novel ELISA-based assay with conventional immunofluorescence

    Institute of Scientific and Technical Information of China (English)

    Dennis CW Poland; Huib Ceelie; Rob B Dinkelaar; Cornelis Beijer

    2006-01-01

    AIM: To evaluate the novel anti-endomysium (anti-EMA)detection based on ELISA.METHODS: Anti-EMA IgA was measured by a novel ELISA in 196 patients with gastrointestinal symptoms and suspected mal-absorption. Data were compared with those obtained by the conventional IF test.RESULTS: A good concordance of 98% was found between these two assays. In sera of 161 patients (82%)both assays tested negative whereas in sera of 31 patients (16%) both assays tested positive for the presence of anti-EMA antibodies. Discrepancies between EMAELISA and EMA-immunofluorescence (IF) were found in only 4 patients (2%).CONCLUSION: This ELISA can replace IF for the detection of anti-EMA antibodies and provide clinicians with an excellent tool to screen for celiac disease in patients with gastrointestinal complaints.

  10. The development of an enzyme-linked immunosorbent assay for Trypanosoma vivax antibodies and its use in epidemiological surveys

    Directory of Open Access Journals (Sweden)

    Claudio R Madruga

    2006-11-01

    Full Text Available There are data indicating that the distribution of Trypanosoma vivax in the Brazilian territory is expanding with potential to reach other areas, where the vectors are present. The detection of anti-trypanosomal antibodies in serum provides important information of the trypanosomal status in cattle herds. For this reason, an enzyme-linked immunosorbent assay (Tv-ELISA-Ab with crude antigen from one Brazilian isolate of T. vivax was developed and evaluated. The sensitivity and specificity were respectively 97.6 and 96.9%. In the evaluation of cross-reactions, three calves inoculated with T. evansi trypimastigotes blood forms showed optical densities (OD under the cut-off during the whole experimental period, except one at 45 days post-inoculation. With relation to Babesia bovis, B. bigemina, and Anaplasma marginale, which are endemic hemoparasites in the studied area, the cross-reactions were shown to be 5.7, 5.3, and 1.1%, respectively. The first serological survey of Pantanal and state of Pará showed that T. vivax is widespread, although regions within both areas had significantly different prevalences. Therefore, this Tv-ELISA-Ab may be a more appropriate test for epidemiological studies in developing countries because the diagnostic laboratories in most countries may be able to perform an ELISA, which is not true for polymerase chain reaction.

  11. Sexing murine embryos with an indirect immunofluorescence assay using phage antibody B9-Fab against SDM antigen.

    Science.gov (United States)

    Wang, Naidong; Yuan, Anwen; Ma, Jun; Deng, Zhibang; Xue, Liqun

    2015-06-01

    The use of serologically detectable male (SDM; also called H-Y) antigens to identify male embryos may be limited by the source of anti-SDM antibody. In the present study, novel anti-SDM B9-Fab recombinant clones (obtained by chain shuffling of an A8 original clone) were used to detect SDM antigens on murine embryos. Murine morulae and blastocysts (n=138) were flushed from the oviducts of Kunming mice and incubated with anti-SDM B9-Fab for 30 min at 37°C. With an indirect immunofluorescence assay, the membrane and inner cell mass had bright green fluorescence (presumptive males). Overall, 43.5% (60/138) were classified as presumptive males and 56.5% (78/138) as presumptive females, with 85.0 and 88.5% of these, respectively, confirmed as correct predictions (based on PCR analysis of a male-specific [Sry] sequence). We concluded that the anti-SDM B9-Fab molecule had potential for non-invasive, technically simple immunological sexing of mammalian embryos.

  12. Development and validation of an enzyme-linked immunosorbent assay for antibodies against Mycobacterium bovis in european wild boar

    Directory of Open Access Journals (Sweden)

    Gortázar Christian

    2008-11-01

    Full Text Available Abstract Background Bovine tuberculosis (bTB remains a significant problem in some parts of Spain largely because of contacts between cattle and wildlife reservoirs in extensive grazing systems. European Wild boar (Sus scrofa is one of the species involved in the transmission of the disease to other species. Fast and simple detection methods would be critical for assessing infection prevalence, study the mechanisms of pathogen transmission and monitoring the effects of TB control measures. Results An enzyme-linked immunosorbent assay (ELISA to detect antibodies against Mycobacterium bovis in wild boar serum was developed and validated on 185 sera from TB positive and negative wild boar. Based on antigen inoculation of captive animals as well as tuberculosis compatible lesions, culture results and molecular analysis of hunted individuals, animals were allocated into two groups: tuberculosis positive group and tuberculosis negative group. After optimization of the positive to negative ratio using different combinations of serum dilutions and conjugate concentrations, the test yielded a sensitivity of 72.60% and a specificity of 96.43% for the best cut-off. Conclusion Although some negative group animals showed an ELISA positive reaction (

  13. A whole blood in vitro cytokine release assay with aqueous monoclonal antibody presentation for the prediction of therapeutic protein induced cytokine release syndrome in humans.

    Science.gov (United States)

    Wolf, Babette; Morgan, Hannah; Krieg, Jennifer; Gani, Zaahira; Milicov, Adriana; Warncke, Max; Brennan, Frank; Jones, Stewart; Sims, Jennifer; Kiessling, Andrea

    2012-12-01

    The administration of several monoclonal antibodies (mAbs) to humans has been associated with acute adverse events characterized by clinically significant release of cytokines in the blood. The limited predictive value of toxicology species in this field has triggered intensive research to establish human in vitro assays using peripheral blood mononuclear cells or blood to predict cytokine release in humans. A thorough characterization of these assays is required to understand their predictive value for hazard identification and risk assessment in an optimal manner, and to highlight potential limitations of individual assay formats. We have characterized a whole human blood cytokine release assay with only minimal dilution by the test antibodies (95% v/v blood) in aqueous presentation format, an assay which has so far received less attention in the scientific world with respect to the evaluation of its suitability to predict cytokine release in humans. This format was compared with a human PBMC assay with immobilized mAbs presentation already well-characterized by others. Cytokine secretion into plasma or cell culture supernatants after 24h incubation with the test mAbs (anti-CD28 superagonist TGN1412-like material (TGN1412L), another anti-CD28 superagonistic mAb (ANC28.1), a T-cell depleting mAb (Orthoclone™), and a TGN1412 isotype-matched control (Tysabri™) not associated with clinically-relevant cytokine release) was detected by a multiplex assay based on electrochemiluminescent excitation. We provide proof that this whole blood assay is a suitable new method for hazard identification of safety-relevant cytokine release in the clinic based on its ability to detect the typical cytokine signatures found in humans for the tested mAbs and on a markedly lower assay background and cytokine release with the isotype-matched control mAb Tysabri™ - a clear advantage over the PBMC assay. Importantly, quantitative and qualitative differences in the relative cytokine

  14. Evaluation of assay interference and interpretation of CXCR4 receptor occupancy results in a preclinical study with MEDI3185, a fully human antibody to CXCR4

    Science.gov (United States)

    Chavez, Carlos; Henderson, Simon; Vainshtein, Inna; Standifer, Nathan; DelNagro, Christopher; Mehrzai, Freshta; Schneider, Amy; Roskos, Lorin; Liang, Meina

    2015-01-01

    Background Receptor occupancy (RO) assays provide a means to measure the direct interaction of therapeutics with their cell surface targets. Free receptor assays quantify cell‐surface receptors not bound by a therapeutic while total receptor assays quantify the amount of target on the cell surface. Methods We developed both a flow cytometry‐based free RO assay to detect free surface CXCR4, and a total surface CXCR4 assay. In an effort to evaluate potential displacement interference, we performed in vitro experiments to compare on‐cell affinity with the IC50 values from in vitro and in vivo from the free CXCR4 assay. We determined free and total surface CXCR4 on circulating blood cells in cynomolgus monkeys dosed with MEDI3185, a fully human monoclonal antibody to CXCR4. Results We devised an approach to evaluate displacement interference during assay development and showed that our free assay demonstrated little to no displacement interference. After dosing cynomolgus monkeys with MEDI3185, we observed dose‐dependence in the magnitude and duration of receptor occupancy and found CXCR4 to increase on lymphocytes, monocytes, and granulocytes. In a multiple dose study, we observed time points where surface CXCR4 appeared fully occupied but MEDI3185 was not detectable in serum. These paradoxical results represented a type of assay interference, and by comparing pharmacokinetic, ADA and total CXCR4 results, the most likely reason for the free CXCR4 results was the emergence of neutralizing anti‐drug antibodies (ADA). The total CXCR4 assay was unaffected by ADA and provided a reliable marker of target modulation in both in vivo studies. © 2015 The Authors Cytometry Part B: Clinical Cytometry Published byWiley Periodicals, Inc. PMID:26384735

  15. A comparison of titers of anti-Brucella antibodies of naturally infected and healthy vaccinated cattle by standard tube agglutination test, microtiter plate agglutination test, indirect hemagglutination assay, and indirect enzyme-linked immunosorbent assay

    Directory of Open Access Journals (Sweden)

    Anju Mohan

    2016-07-01

    Full Text Available Aim: We determined the antibody response in cattle naturally infected with brucellosis and normal healthy adult cattle vaccinated during calf hood with strain 19. Materials and Methods: The antibody titers were measured by standard tube agglutination test (STAT, microtiter plate agglutination test (MAT, indirect hemagglutination assay (IHA, and indirect enzyme-linked immunosorbent assay (iELISA as per standard protocols. Results: The mean STAT titers were 1.963±0.345 in infected cattle and 1.200±0.155 in healthy vaccinated cattle. The difference was extremely significant (p<0.0001. The mean MAT titers were 2.244±0.727 in infected cattle and 1.200±0.155 in healthy vaccinated cattle. The difference was very significant (p<0.005. The mean IHA titers in infected cattle were 2.284±0.574, and those in healthy vaccinated cattle were 1.200±0.155. The difference was extremely significant (p=0.0002. However, the difference in mean iELISA titers of infected cattle (1.3678±0.014 and healthy vaccinated cattle (1.367±0.014 was non-significant. The infected animals showed very high titers of agglutinating antibodies compared to the vaccinated animals. However, it cannot be ascertained whether these antibodies are due to vaccine or response to infection. Since the infected animals had been vaccinated earlier, the current infection may suggest that vaccination was unable to induce protective levels of antibody. The heightened antibody response after infection may also indicate a secondary immune response to the antigens common to the vaccine strain and wild Brucella organisms. Conclusion: The brucellosis infected animals showed very high titers of agglutinating antibodies compared to the vaccinated animals.

  16. Establishment of the Method of Immunohistochemistry Assay for the Detection of Scrapie in Chinese Short-Tailed Han Sheep by Monoclonal Antibody

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The method of immunohistochemistry assay for the detection of scrapie in Chinese Short-tailed Han sheep was established using monoclonal antibody. Genomic DNA was isolated from Chinese Short-tailed Han sheep blood. Using the polymerase chain reaction technique, PrP27-30 gene sequence was amplified from Chinese Short-tailed Han sheep genomic DNA. By recombinant DNA technology, the recombinant protein of Chinese Short-tailed Han sheep PrP27-30 was obtained. Then, using standard methodology of myeloma cell fusion, a panel of monoclonal antibodies was generated. With mAbs, scrapie in Chinese Short-tailed Han sheep was detected by immunohistochemistry assay. The recombinant protein of Chinese Short-tailed Han sheep PrP27-30 was obtained and a panel of six hybridoma cell lines secreting specific antibodies to Chinese Short-tailed Han sheep PrP27-30 related to scrapie was obtained with one fusion between myeloma Sp2/0 and spleen cells from mice immunized with the purified recombinant protein. Four hybridoma cell lines can be used in immunohistochemistry assay for the detection of scrapie in Chinese Short-tailed Han sheep. So that the special monoclonal antibody developed in author's institute can be used to detect PrPsc of scrapie in Chinese Short-tailed Han sheep by immunohistochemistry in China.

  17. Murine monoclonal antibody to platelet factor 4/heparin complexes as a potential reference standard for platelet activation assays in heparin-induced thrombocytopenia.

    Science.gov (United States)

    Asada, Reiko; Wanaka, Keiko; Walenga, Jeanine; Prechel, Margaret; Miyashita, Kumiko; Escalante, Vicki; Kaneko, Chieko; Hoshino, Nobuhiro; Oosawa, Mitsuru; Matsuo, Miyako

    2013-01-01

    Quality control of the platelet activation assays to diagnose heparin-induced thrombocytopenia (HIT), (14)C-serotonin release assay (SRA) and platelet aggregation test (PAT) has yet to be established due to lack of reference standards and the difficulty of obtaining significant amounts of HIT antibodies from patients with HIT. We prepared a murine monoclonal antibody to human platelet factor 4 (hPF4)/heparin complexes (HIT-MoAb) and investigated the platelet activating action of HIT-MoAb by using SRA and PAT. The HIT-MoAb activated human platelets at low heparin concentration and the platelet activations were inhibited at high heparin concentration in both SRA and PAT. The HIT-MoAb produced a concentration-dependent effect. Moreover, the platelet activation at low heparin concentration was inhibited by anti-FcγRIIa antibody. These results indicated that HIT-MoAb has characteristics similar to human HIT antibodies regarding heparin-dependent platelet activation. Therefore, it is suggested that HIT-MoAb has the potential to be a positive control or reference standard in platelet activation assays.

  18. Comparison of Two Assays to Determine Anti-Citrullinated Peptide Antibodies in Rheumatoid Arthritis in relation to Other Chronic Inflammatory Rheumatic Diseases: Assaying Anti-Modified Citrullinated Vimentin Antibodies Adds Value to Second-Generation Anti-Citrullinated Cyclic Peptides Testing

    Directory of Open Access Journals (Sweden)

    Miriam Lizette Díaz-Toscano

    2014-01-01

    Full Text Available Determination of anti-citrullinated peptide antibodies (ACPA plays a relevant role in the diagnosis of rheumatoid arthritis (RA. To date, it is still unclear if the use of several tests for these autoantibodies in the same patient offers additional value as compared to performing only one test. Therefore, we evaluated the performance of using two assays for ACPA: second-generation anti-citrullinated cyclic peptides antibodies (anti-CCP2 and anti-mutated citrullinated vimentin (anti-MCV antibodies for the diagnosis of RA. We compared three groups: RA (n=142, chronic inflammatory disease (CIRD, n=86, and clinically healthy subjects (CHS, n=56 to evaluate sensitivity, specificity, predictive values, and likelihood ratios (LR of these two assays for the presence of RA. A lower frequency of positivity for anti-CCP2 was found in RA (66.2% as compared with anti-MCV (81.0%. When comparing RA versus other CIRD, sensitivity increased when both assays were performed. This strategy of testing both assays had high specificity and LR+. We conclude that adding the assay of anti-MCV antibodies to the determination of anti-CCP2 increases the sensitivity for detecting seropositive RA. Therefore, we propose the use of both assays in the initial screening of RA in longitudinal studies, including early onset of undifferentiated arthritis.

  19. Comparison of Two Assays to Determine Anti-Citrullinated Peptide Antibodies in Rheumatoid Arthritis in relation to Other Chronic Inflammatory Rheumatic Diseases: Assaying Anti-Modified Citrullinated Vimentin Antibodies Adds Value to Second-Generation Anti-Citrullinated Cyclic Peptides Testing

    Science.gov (United States)

    Díaz-Toscano, Miriam Lizette; Olivas-Flores, Eva Maria; Zavaleta-Muñiz, Soraya Amali; Gamez-Nava, Jorge Ivan; Cardona-Muñoz, Ernesto German; Ponce-Guarneros, Manuel; Castro-Contreras, Uriel; Nava, Arnulfo; Salazar-Paramo, Mario; Celis, Alfredo; Fajardo-Robledo, Nicte Selene; Corona-Sanchez, Esther Guadalupe; Gonzalez-Lopez, Laura

    2014-01-01

    Determination of anti-citrullinated peptide antibodies (ACPA) plays a relevant role in the diagnosis of rheumatoid arthritis (RA). To date, it is still unclear if the use of several tests for these autoantibodies in the same patient offers additional value as compared to performing only one test. Therefore, we evaluated the performance of using two assays for ACPA: second-generation anti-citrullinated cyclic peptides antibodies (anti-CCP2) and anti-mutated citrullinated vimentin (anti-MCV) antibodies for the diagnosis of RA. We compared three groups: RA (n = 142), chronic inflammatory disease (CIRD, n = 86), and clinically healthy subjects (CHS, n = 56) to evaluate sensitivity, specificity, predictive values, and likelihood ratios (LR) of these two assays for the presence of RA. A lower frequency of positivity for anti-CCP2 was found in RA (66.2%) as compared with anti-MCV (81.0%). When comparing RA versus other CIRD, sensitivity increased when both assays were performed. This strategy of testing both assays had high specificity and LR+. We conclude that adding the assay of anti-MCV antibodies to the determination of anti-CCP2 increases the sensitivity for detecting seropositive RA. Therefore, we propose the use of both assays in the initial screening of RA in longitudinal studies, including early onset of undifferentiated arthritis. PMID:25025037

  20. Evaluation of an enzyme-linked immunosorbent assay (ELISA) for the detection of Campylobacter jejuni antibodies, and comparison with a complement fixation test (CFT).

    Science.gov (United States)

    Oosterom, J; den Uyl, C H; Bänffer, J R; Lauwers, S; Huisman, J; Busschbach, A E; Poelma, F G; Bellemans, R

    1985-01-01

    An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of total anti-Campylobacter immunoglobulins in human sera. In this assay disintegrated Campylobacter bacteria were used as the antigen. Absorption tests including other possibly enteropathogenic bacterial species showed that the ELISA system displayed a high immunological specificity for Campylobacter. Using this ELISA it was found that in about 80% of Campylobacter patients these Campylobacter antibodies are produced to almost maximal levels within 8 days after onset of disease, and that they may persist for at least 4 months. Indeed, Campylobacter antibodies were demonstrated at low levels in a large number of control sera. However, accepting an antibody titre of 1:640 as indicative of Campylobacter infection, the statistical sensitivity of the ELISA system was 77% and the specificity 95%. In an epidemiological survey a high association was demonstrated between the severity of Campylobacter-related symptoms and antibody titre values. Assessment of Campylobacter antibody titres by means of this ELISA and by a complement fixation test in 92 sera from index patients and contacts with and without symptoms showed a high association of results.

  1. Comparison of two high-throughput assays for quantification of adenovirus type 5 neutralizing antibodies in a population of donors in China.

    Directory of Open Access Journals (Sweden)

    Qiang Liu

    Full Text Available BACKGROUND: The presence of various levels of Adenovirus serotype 5 neutralizing antibodies (Ad5NAb is thought to contribute to the inconsistent clinical results obtained from vaccination and gene therapy studies. Currently, two platforms based on high-throughput technology are available for Ad5NAb quantification, chemiluminescence- and fluorescence-based assays. The aim of this study was to compare the results of two assays in the seroepidemiology of Ad5NAb in a local population of donors. METHODOLOGY/PRINCIPAL FINDINGS: The fluorescence-based neutralizing antibody detection test (FRNT using recombinant Ad5-EGFP virus and the chemiluminescence-based neutralizing antibody test (CLNT using Ad5-Fluc were developed and standardized for detecting the presence of Ad5NAb in serum samples from the population of donors in Beijing and Anhui provinces, China. First, the overall percentage of people positive for Ad5NAb performed by CLNT was higher than that obtained by FRNT (85.4 vs 69.9%, p<0.001. There was an 84.5% concordance between the two assays for the 206 samples tested (144 positive in both assays and 30 negative in both assays. All 32 discordant sera were CLNT-positive/FRNT-negative and were confirmed positive by western blot. Secondly, for all 144 sera positive by both assays, the two assays showed high correlation (r = 0.94, p<0.001 and close agreement (mean difference: 0.395 log(10, 95% CI: -0.054 log(10 to 0.845 log(10. Finally, it was found by both assays that there was no significant difference observed for titer or prevalence by gender (p = 0.503 vs 0.818, for two assays; however, age range (p = 0.049 vs 0.010 and geographic origin (p = 0.007 vs 0.011 were correlated with Ad5NAb prevalence in northern regions of China. CONCLUSION: The CLNT assay was relatively more simple and had higher sensitivity than the FRNT assay for determining Ad5NAb titers. It is strongly suggested that the CLNT assay be used for future

  2. A cell-based time-resolved fluorescence assay for selection of antibody reagents for G protein-coupled receptor immunohistochemistry.

    Science.gov (United States)

    Su, Jui-Lan; Fornwald, Jim; Rivers, Philip; Goldsworthy, Susan; Looney, Noeleen A; Hanvey, Jeff; Plumpton, Chris; Parham, Janet; Romanos, Michael; Kost, Thomas A; Kull, Frederick C

    2004-08-01

    A cell-based time-resolved fluorescence (celTRF) immunoassay is described for pre-screening antibodies to G protein-coupled receptor (GPCR) peptides that predicts suitability for immunohistochemistry (IHC). Rat GPCRs were expressed in Saos-2 human osteosarcoma cells via recombinant baculoviruses designed for mammalian cell expression, i.e., the transduced cells were used as a "screening lawn". The lawn was fixed and permeabilized similarly to IHC tissue. The celTRF, a dissociation-enhanced lanthanide fluorescence immunoassay (DELFIA), employed Eu-labelled goat anti-rabbit IgG. It exhibited a broad dynamic range upon which enzyme-linked immunosorbant assay (ELISA)-positive affinity-purified anti-peptide antibody reagents were examined for specificity and potency. Over 150 anti-peptide reagents to 27 GPCRs were characterized. All celTRF-positive antibodies were found to be suitable for IHC, whereas ELISA alone did not predict IHC utility. Examples are illustrated with five rabbit anti-neuropeptide FF receptor 1 (NPFF1) antibodies, where a strong correlation between celTRF potency and IHC utility was observed in both applications. In contrast, two high anti-peptide ELISA titer but celTRF-negative antibodies failed to recognize the NPFF1 receptor in IHC. The celTRF assay was performed manually and in an automated fashion, in our case, using a Biomek FX station and Sami scheduling software. The celTRF is the first in vitro automated assay that offers confident pre-selection of antibodies for IHC and the versatility to accommodate the rapid screening of large numbers of GPCRs. The celTRF is readily applicable to other protein target classes.

  3. Second generation of pseudotype-based serum neutralization assay for Nipah virus antibodies: sensitive and high-throughput analysis utilizing secreted alkaline phosphatase.

    Science.gov (United States)

    Kaku, Yoshihiro; Noguchi, Akira; Marsh, Glenn A; Barr, Jennifer A; Okutani, Akiko; Hotta, Kozue; Bazartseren, Boldbaatar; Fukushi, Shuetsu; Broder, Christopher C; Yamada, Akio; Inoue, Satoshi; Wang, Lin-Fa

    2012-01-01

    Nipah virus (NiV), Paramyxoviridae, Henipavirus, is classified as a biosafety level (BSL) 4 pathogen, along with the closely related Hendra virus (HeV). A novel serum neutralization test was developed for measuring NiV neutralizing antibodies under BSL2 conditions using a recombinant vesicular stomatitis virus (VSV) expressing secreted alkaline phosphatase (SEAP) and pseudotyped with NiV F/G proteins (VSV-NiV-SEAP). A unique characteristic of this novel assay is the ability to obtain neutralization titers by measuring SEAP activity in supernatant using a common ELISA plate reader. This confers a remarkable advantage over the first generation of NiV-pseudotypes expressing green fluorescent protein or luciferase, which require expensive and specific measuring equipment. Using panels of NiV- and HeV-specific sera from various species, the VSV-NiV-SEAP assay demonstrated neutralizing antibody status (positive/negative) consistent with that obtained by conventional live NiV test, and gave higher antibody titers than the latter. Additionally, when screening sixty-six fruit bat sera at one dilution, the VSV-NiV-SEAP assay produced identical results to the live NiV test and only required a very small amount (2μl) of sera. The results suggest that this novel VSV-NiV-SEAP assay is safe, useful for high-throughput screening of sera using an ELISA plate reader, and has high sensitivity and specificity.

  4. The level of heparin-induced antibodies in correlation with the result of the flow cytometric functional assay in the patients with suspected HIT.

    Science.gov (United States)

    Maličev, Elvira; Maček Kvanka, Marjeta; Klemenc, Polona; Rožman, Primož

    2017-09-13

    Heparin can induce the formation of antibodies against a heparin complex with a platelet factor 4 (PF4), leading to platelet activation and the development of heparin-induced thrombocytopaenia (HIT). Because screening ELISA does not discriminate between platelet activating and non-activating anti-heparin/PF4 antibodies, each positive result is confirmed by an additional functional assay. We analysed 1004 sera of patients with suspected HIT. Optical density (OD) values of ELISA-positive results were correlated with the risk for a positive result with our functional flow cytometric assay. Only 10.7% were ELISA positive and 59.8% of those were positive with the functional assay. The positive functional assay was found in 23.4% of patients with OD2.0. Although our results showed that higher ELISA OD values increasethe possibility of the presence of platelet-activating anti-heparin/PF4 antibodies - , there is no need for improving ELISA cut-off value for positive result. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  5. A liquid-phase-blocking concanavalin A enzyme-linked immunosorbent assay for the detection of antibodies against Newcastle disease virus in serum of free-ranging pigeons.

    Science.gov (United States)

    de Oliveira, Elisabete Schirato; Silva, Ketherson Rodrigues; Fernando, Filipe Santos; Gonçalves, Mariana Costa Mello; Fernandes, Camila Cesário; Borzi, Mariana Monezi; dos Santos, Romeu Moreira; Tamanini, Maria de Lourdes Feres; Montassier, Maria de Fátima da Silva; Montassier, Helio José

    2013-11-01

    A competitive liquid-phase-blocking concanavalin A enzyme-linked immunosorbent assay (LPB-ConA-ELISA) was developed in the current study. The assay used ConA as a capture reagent, and the sera of specific pathogen-free chickens immunized with nonpurified Newcastle disease virus (NDV) suspension as detector antibodies, to detect and quantify specific antiviral antibodies in serum samples from free-ranging pigeons. The comparison between the LPB-ConA-ELISA and the hemagglutination inhibition (HI) test for the detection of antibodies in serum samples from 107 pigeons showed significant correlation between the assays (r = 0.875), a high sensitivity (100%), specificity (95.8%), accuracy (96.3%) for the ELISA, and good agreement (κ = 0.83) between the 2 assays. The results of this study suggest that the LPB-ConA-ELISA could be a useful alternative to HI test in the serodiagnosis of NDV in pigeons, or other species of birds.

  6. Development of an Enzyme-Linked Immunosorbent Assay Based on Fusion VP2332-452 Antigen for Detecting Antibodies against Aleutian Mink Disease Virus.

    Science.gov (United States)

    Chen, Xiaowei; Song, Cailing; Liu, Yun; Qu, Liandong; Liu, Dafei; Zhang, Yun; Liu, Ming

    2016-02-01

    For detection of Aleutian mink disease virus (AMDV) antibodies, an enzyme-linked immunosorbent assay (ELISA) was developed using the recombinant VP2332-452 protein as an antigen. Counterimmunoelectrophoresis (CIEP) was used as a reference test to compare the results of the ELISA and Western blotting (WB); the specificity and sensitivity of the VP2332-452 ELISA were 97.9% and 97.3%, respectively, which were higher than those of WB. Therefore, this VP2332-452 ELISA may be a preferable method for detecting antibodies against AMDV.

  7. Quantitative estimation of diphtheria and tetanus toxoids. 6. Use of different antibody titration methods for evaluation of immunogenicity in animals during potency assay of diphtheria toxoid.

    Science.gov (United States)

    Lyng, J; Heron, I

    1992-06-01

    Two diphtheria toxoid preparations were compared in potency assays in guinea-pigs using different methods for evaluation of the responses to vaccination. The methods used were the direct skin challenge (Schick test) and ELISA and VERO cell titration of antibodies. The different evaluation methods resulted in the same relative potencies between the toxoids. It was observed that when first-vaccination sera were compared with a second-vaccination serum, the relative antibody concentration depended on whether ELISA or VERO cell titration was used.

  8. Technical note: Hapten synthesis, antibody production and development of an enzyme-linked immunosorbent assay for detection of the natural steroidal alkaloid Dendrogenin A.

    Science.gov (United States)

    de Medina, Philippe; Paillasse, Michael R; Segala, Gregory; Al Saati, Talal; Boyes, Jeannine; Delsol, Georges; Allal, Cuider; Marsili, Sabrina; Silvente-Poirot, Sandrine; Poirot, Marc

    2013-03-01

    We have recently discovered the existence of 5α-Hydroxy-6β-[2-(1H-imidazol-4-yl)ethylamino]cholestan-3β-ol, called Dendrogenin A (DDA), as the first endogenous steroidal alkaloid ever described in mammals. We found that the DDA content of tumors and cancer cell lines was low or absent compared with normal cells showing that a deregulation in DDA biosynthesis was associated with cancer and therefore suggesting that DDA could represent a metabolomic cancer biomarker. This prompted us to produce antibodies that selectively recognize DDA. For this purpose, the hapten 5α-hydroxy-6β-[2-(1H-imidazol-4-yl)ethylamino]cholestan-3β-o-hemisuccinate with a carboxylic spacer arm attached to the 3β-hydroxyl group of DDA was synthesized. The hapten was coupled to bovine serum albumin and keyhole limpet hemocyanin for antibody production to develop an enzyme-linked immunosorbent assay (ELISA). The protein conjugates were injected into BALB/c mice to raise antibodies. The monoclonal antibodies that were secreted from the hybridoma cell lines established were assessed with indirect ELISA by competitive assays using dilutions of a DDA standard. The antibodies from the selected hybridomas had an IC(50) value ranging from 0.8 to 425 ng/ml. Three antibodies showed no cross-reactivity with structurally related compounds including histamine, cholesterol, ring B oxysterols and a regio-isomer of DDA. In this study, high-affinity and selective antibodies against DDA were produced for the first time, and a competitive indirect ELISA was developed.

  9. A novel bead-based assay to detect specific antibody responses against Toxoplasma gondii and Trichinella spiralis simultaneously in sera of experimentally infected swine

    Directory of Open Access Journals (Sweden)

    Bokken Gertie CAM

    2012-03-01

    Full Text Available Abstract Background A novel, bead-based flow cytometric assay was developed for simultaneous determination of antibody responses against Toxoplasma gondii and Trichinella spiralis in pig serum. This high throughput screening assay could be an alternative for well known indirect tests like ELISA. One of the advantages of a bead-based assay over ELISA is the possibility to determine multiple specific antibody responses per single sample run facilitated by a series of antigens coupled to identifiable bead-levels. Furthermore, inclusion of a non-coupled bead-level in the same run facilitates the determination of, and correction for non-specific binding. The performance of this bead-based assay was compared to one T. spiralis and three T. gondii ELISAs. For this purpose, sera from T. gondii and T. spiralis experimentally infected pigs were used. With the experimental infection status as gold standard, the area under the curve, Youden Index, sensitivity and specificity were determined through receiver operator curve analysis. Marginal homogeneity and inter-rater agreement between bead-based assay and ELISAs were evaluated using McNemar's Test and Cohen's kappa, respectively. Results Results indicated that the areas under the curve of the bead-based assay were 0.911 and 0.885 for T. gondii and T. spiralis, respectively, while that of the T. gondii ELISAs ranged between 0.837 and 0.930 and the T. spiralis ELISA was 0.879. Bead-based T. gondii assay had a sensitivity of 86% and specificity of 96%, while the ELISAs ranged between 64-84% and 93-99%, respectively. The bead-based T. spiralis assay had a sensitivity of 68% and specificity of 100% while the ELISA scored 72% and 95%, respectively. Marginal homogeneity was found between the T. gondii bead-based test and one of the T. gondii ELISAs. Moreover, in this test combination and between T. spiralis bead-based assay and respective ELISA, an excellent inter-rater agreement was found. When results of

  10. Particle counting assay for anti-toxoplasma IgG antibodies. Comparison with four automated commercial enzyme-linked immunoassays.

    Science.gov (United States)

    Galanti, L M; Dell'Omo, J; Wanet, B; Guarin, J L; Jamart, J; Garrino, M G; Masson, P L; Cambiaso, C L

    1997-09-24

    An assay for anti-toxoplasma IgG antibodies based on agglutination of latex particles was set up and compared with commercial immunoassays. The reaction was measured by instrumental counting of particles remaining unagglutinated. The running time was 45 min. This test (PaC) was compared using 243 serum samples with four automated commercial immunoassays: the Enzymum test Toxo IgG (ES300, Boehringer), the Vidas Toxo IgG (Biomérieux), the IMX Toxo IgG (Abbott), the Magia Toxoplasma gondii IgG (Merck). The mean values (+/- SD) obtained by IMX (25 IU +/- 68) and ES300 (45 IU +/- 142) were significantly lower than the values obtained by Vidas (73 IU +/- 237, p Magia (80 IU +/- 300, p < 10(-4) and p = 0.0005) and by PaC (70 IU +/- 260, p < 10(-4) and p = 0.0126). The correlations between PaC and Toxo IgG Boehringer, Biomérieux, Abbott, Merck were r = 0.97, r = 0.98, r = 0.94, r = 0.98, respectively. The correlation coefficients between the enzyme-immunoassays ranged from 0.96 to 0.99. All positive samples by PaC were found to be positive by enzyme-immunoassays except for eight sera which were doubtful positives by the Enzymum test ToxoIgG from Boehringer. No negative sample by PaC was found positive by any of the enzyme-immunoassays. In PaC, when two latex preparations coated with different antigen were compared, the correlation was rather weak (r = 0.93) suggesting that the selection of the antigen can be critical. In conclusion, the four automated commercial immunoassays now available gave similar results. However, the discrepancies observed in this study underlined the importance of clinical and biological follow-up of the patients and the necessity to confirm the result. The introduction of a new technique such as PaC, which is now available for a large variety of assays in Clinical Chemistry and Microbiology, is justified by its intrinsic advantage of homogeneity. Therefore, automation is easy as well as the control of possible interference.

  11. Rheumatoid arthritis and its association with HLA-DR antigens. II. Antibodies to native connective tissue antigens detected by enzyme linked immunosorbent assay.

    Science.gov (United States)

    Pesoa, S A; Vullo, C M; Onetti, C M; Riera, C M

    1989-01-01

    The distribution of frequencies of HLA-DR alloantigens in HLA-DR4 negative subjects was determined in patients with Rheumatoid arthritis (RA) and normal individuals. An increased incidence of HLA-DR1 alloantigen in DR4 negative RA patients (45.9%) compared with DR4 negative healthy controls (23.6%) was found. The difference became significant when the incidence of DR1 was compared between patients with severe disease stages (III-IV) (75%) in contrast to 32% of incidence in patients of the milder stages (I-II) (p less than 0.05). Using Enzyme Linked Immunosorbent Assay we have determined the incidence of serum antibodies to native bovine type I and type II collagens and proteoglycans in patients with RA. Presence of serum antibodies to native type I collagen was detected in 59% of patients with RA, 60% of sera exhibited reactivity to type II collagen and 12% had antibodies to proteoglycans. There was no correlation between the presence of antibodies to type I and II collagens and disease stages, however, the incidence of serum antibodies to proteoglycans was increased in severe disease stages. On the other hand, the presence of high levels of antibodies to type I collagen was associated to HLA-DR1 antigen, (p less than 0.05).

  12. Comparison between indirect enzyme-linked immunosorbent assays for Anaplasma marginale antibodies with recombinant major surface protein 5 and initial body antigens

    Directory of Open Access Journals (Sweden)

    Virgínia MG Silva

    2006-08-01

    Full Text Available Indirect enzyme-linked immunosorbent assays (ELISAs based on recombinant major surface protein 5 (rMSP5 and initial body (IB antigens from a Brazilian isolate of Anaplasma marginale were developed to detect antibodies against this rickettsia in cattle. Both tests showed the same sensitivity (98.2% and specificities (100% for rMSP5 and 93.8% for IB ELISA which did not differ statistically. No cross-reactions were detected with Babesia bigemina antibodies, but 5 (rMSP5 ELISA to 15% (IB ELISA of cross-reactions were detected with B. bovis antibodies. However, such difference was not statistically significant. Prevalences of seropositive crossbred beef cattle raised extensively in Miranda county, state of Mato Grosso do Sul, Brazil, were 78.1% by rMSP5 ELISA and 79.7% by IB ELISA. In the analysis of sera from dairy calves naturally-infected with A. marginale, the dynamics of antibody production was very similar between both tests, with maternal antibodies reaching the lowest levels at 15-30 days, followed by an increase in the mean optical densities in both ELISAs, suggesting the development of active immunity against A. marginale. Results showed that all calves were seropositive by one-year old, characterizing a situation of enzootic stability. The similar performances of the ELISAs suggest that both tests can be used in epidemiological surveys for detection of antibodies to A. marginale in cattle.

  13. Enzyme-linked immunosorbent assay for detection of immunoglobulin G antibodies to Escherichia coli Vero cytotoxin 1.

    Science.gov (United States)

    Karmali, M A; Petric, M; Winkler, M; Bielaszewska, M; Brunton, J; van de Kar, N; Morooka, T; Nair, G B; Richardson, S E; Arbus, G S

    1994-06-01

    The frequency of Vero cytotoxin 1 (VT1)-neutralizing antibody (NAb) in serum specimens from 790 age-stratified (0 to 70 years) control individuals from Toronto was 61 of 790 (7.7%), with a peak of 19% in the 20- to 30-year-old age group and a second peak of 16.7% in the 60- to 70-year-old age group. A total of 568 serum specimens, including 538 from the 790 Toronto control subjects, 21 from patients from three outbreaks of VT-producing Escherichia coli (VTEC) infection, and 9 known VT1-NAb-positive serum specimens from patients with hemolytic-uremic syndrome (HUS), were then tested for the presence of anti-VT1 immunoglobulin G (IgG) by an enzyme-linked immunosorbent assay (ELISA). The mean ELISA values of 522 VT1-NAb-negative serum specimens and 46 VT1-NAb-positive serum specimens were 0.09 +/- 0.06 (range, 0 to 0.56) and 0.78 +/- 0.66 (range, 0.16 to 2.91), respectively (P < 0.001; Student's t test). With a breakpoint of 0.21 (mean ELISA value of the VT1-NAb-negative sera + 2 standard deviations), the sensitivity, specificity, positive predictive value, and negative predictive value of the VT1 IgG ELISA compared with those of the VT1-NAb assay were, respectively, 95.7, 98.7, 86.3, and 99.6%. There were nine discrepant serum specimens, of which seven were anti-VT1 IgG positive and VT1-NAb negative and two were anti-VT1 IgG negative and VT1-NAb positive. The ELISA was also used for testing 238 control serum specimens from The Netherlands, Japan, and India and acute- and convalescent-phase serum specimens from 42 Toronto patients with HUS. The frequencies of anti-VT1 IgG (with VT1-NAb frequencies in parantheses) in control sera from the Netherlands, Japan, and India were 6% (3%), 1.1% (0%), and 12% (10%), respectively, with no age clustering. The frequencies of anti-VT1 IgG seropositivity in HUS patients were 5 of 14 (35.7%) in patients with unknown toxin exposure, 2 of 22 (9.1%) in individuals with known exposure to VT1 plus VT2 or VT1 alone, and 0 of 6 (0%) in

  14. Development of a Luminex assay for the detection of swine antibodies to non-structural proteins of foot-and-mouth disease virus.

    Science.gov (United States)

    Chen, Tsu-Han; Lee, Fan; Lin, Yeou-Liang; Pan, Chu-Hsiang; Shih, Chia-Ni; Lee, Ming-Chang; Tsai, Hsiang-Jung

    2013-10-31

    Foot-and mouth disease (FMD), swine vesicular disease (SVD), and vesicular stomatitis (VS) are highly contagious vesicular diseases of swine but are not easy to differentiate clinically. For the purpose of instant detecting of FMD and differentiating it from the other vesicular diseases, a Luminex assay was developed. Sera from 64 infected, 307 vaccinated, and 280 naïve pigs were tested by the Luminex assay. Diagnostic sensitivity of the assay was 100%. Diagnostic specificity of the assay was 98.7% in vaccinated pigs and 97.5% to 100% in naïve pigs. Agreement between the results from the Luminex assay and those from a 3ABC polypeptide blocking ELISA was 96.3% with kappa statistics of 0.92. The Luminex assay can detect the immune response to NSP-3ABC in swine as early as eight days post-infection. Moreover, all of the 15 vaccinated but unprotected pigs were all detected by the Luminex assay. The results indicated that the Luminex assay has potential with specificity in detecting antibodies to FMDV 3ABC NSP and in distinguishing FMDV-infected pigs from with either SVDV or VSV. © 2013 Elsevier B.V. All rights reserved.

  15. Enzymic colorimetry-based DNA chip: a rapid and accurate assay for detecting mutations for clarithromycin resistance in the 23S rRNA gene of Helicobacter pylori.

    Science.gov (United States)

    Xuan, Shi-Hai; Zhou, Yu-Gui; Shao, Bo; Cui, Ya-Lin; Li, Jian; Yin, Hong-Bo; Song, Xiao-Ping; Cong, Hui; Jing, Feng-Xiang; Jin, Qing-Hui; Wang, Hui-Min; Zhou, Jie

    2009-11-01

    Macrolide drugs, such as clarithromycin (CAM), are a key component of many combination therapies used to eradicate Helicobacter pylori. However, resistance to CAM is increasing in H. pylori and is becoming a serious problem in H. pylori eradication therapy. CAM resistance in H. pylori is mostly due to point mutations (A2142G/C, A2143G) in the peptidyltransferase-encoding region of the 23S rRNA gene. In this study an enzymic colorimetry-based DNA chip was developed to analyse single-nucleotide polymorphisms of the 23S rRNA gene to determine the prevalence of mutations in CAM-related resistance in H. pylori-positive patients. The results of the colorimetric DNA chip were confirmed by direct DNA sequencing. In 63 samples, the incidence of the A2143G mutation was 17.46 % (11/63). The results of the colorimetric DNA chip were concordant with DNA sequencing in 96.83 % of results (61/63). The colorimetric DNA chip could detect wild-type and mutant signals at every site, even at a DNA concentration of 1.53 x 10(2) copies microl(-1). Thus, the colorimetric DNA chip is a reliable assay for rapid and accurate detection of mutations in the 23S rRNA gene of H. pylori that lead to CAM-related resistance, directly from gastric tissues.

  16. Antibodies to immunoglobulin-G in dog sera, synovial fluids and aqueous humor : a comparative study of rheumatoid factor assays, suitable for routine application

    OpenAIRE

    Bernadina, W.E.; Kol, P.J. van; Willemse, A.

    1988-01-01

    The incidence of anti-IgG antibodies (rheumatoid factors, RF) in body fluids (sera, synovial fluids and aqueous humor) selected from 62 normal and 275 diseased dogs was studied. Fluids were assayed by canine versions of standard agglutinating and/or precipitating RF assays with routine application in human practice. The number of RF detected by dog IgG-coated particles was substantially higher by latex fixation test (LFT) than by modified Rose-Waaler (RW) test (61/144 vs. 14/144). This did no...

  17. An Improved Ultrasensitive Enzyme-Linked Immunosorbent Assay Using Hydrangea-Like Antibody-Enzyme-Inorganic Three-in-One Nanocomposites.

    Science.gov (United States)

    Wei, Tianxiang; Du, Dan; Zhu, Mei-Jun; Lin, Yuehe; Dai, Zhihui

    2016-03-01

    Protein-inorganic nanoflowers, composed of protein and copper(II) phosphate (Cu3(PO4)2), have recently grabbed people's attention. Because the synthetic method requires no organic solvent and because of the distinct hierarchical nanostructure, protein-inorganic nanoflowers display enhanced catalytic activity and stability and would be a promising tool in biocatalytical processes and biological and biomedical fields. In this work, we first coimmobilized the enzyme, antibody, and Cu3(PO4)2 into a three-in-one hybrid protein-inorganic nanoflower to enable it to possess dual functions: (1) the antibody portion retains the ability to specifically capture the corresponding antigen; (2) the nanoflower has enhanced enzymatic activity and stability to produce an amplified signal. The prepared antibody-enzyme-inorganic nanoflower was first applied in an enzyme-linked immunosorbent assay to serve as a novel enzyme-labeled antibody for Escherichia coli O157:H7 (E. coli O157:H7) determination. The detection limit is 60 CFU L(-1), which is far superior to commercial ELISA systems. The three-in-one antibody (anti-E. coli O157:H7 antibody)-enzyme (horseradish peroxidase)-inorganic (Cu3(PO4)2) nanoflower has some advantages over commercial enzyme-antibody conjugates. First, it is much easier to prepare and does not need any complex covalent modification. Second, it has fairly high capture capability and catalytic activity because it is presented as aggregates of abundant antibodies and enzymes. Third, it has enhanced enzymatic stability compared to the free form of enzyme due to the unique hierarchical nanostructure.

  18. Platelet antibody screening by flow cytometry is more sensitive than solid phase red cell adherence assay and lymphocytotoxicity technique: a comparative study in Thai patients.

    Science.gov (United States)

    Buakaew, Jarin; Promwong, Charuporn

    2010-01-01

    The objective of this study was to compare the sensitivity and specificity of lymphocytotoxicity test (LCT), solid phase red cell adherence assay (SPRCA) and flow cytometry in detecting platelet reactive antibodies against human leukocyte antigens (HLA) class I and human platelet antigens (HPA). Sera from 38 thrombocytopenic patients and 5 mothers of thrombocytopenic newborns were screened for platelet reactive antibodies by these three methods using screening platelets and/or lymphocytes panels derived from six subjects. The sensitivity and specificity of each method and levels of agreement were analysed. HLA antibodies were found in 18, 17 and 19 out of 43 patients' sera tested by LCT, SPRCA and flow cytometry, respectively. Four out of 43 patients' sera were reactive against HPA by flow cytometry, but were reactive to only 2 sera by SPRCA. Using flow cytometry as the reference method, the sensitivities/specificities of SPRCA and LCT in HLA antibody detection were 84.21/95.83% and 94.73/100%, respectively, with a good strength of agreement. SPRCA had 50% sensitivity and 100% specificity in HPA antibody detection compare to flow cytometry. Flow cytometry appeared to be the most sensitive technique compared with SPRCA and LCT for both HPA and HLA antibody screening. SPRCA sensitivity was too low for HPA antibody detection, but this might be because of the small number of samples. There was one serum from the mother of a baby suffering neonatal alloimmune thrombocytopenia (NAIT), in whom SPRCA could not detect HPA antibodies, while flow cytometry came out positive. Therefore, SPRCA should not be used in NAIT investigation and flow cytometry should be employed instead.

  19. The enzyme linked immunosorbent assay (ELISA) for the determination of circulating antigen and antibody in Schistosoma haematobium-infected baboons.

    Science.gov (United States)

    Ismail, M M; James, C; Webbe, G

    1981-01-01

    The ELISA was used to measure circulating antigen and antibody in four baboons of which three were treated. The circulating antigen appeared earlier after infection than the antibody which eventually, however, reached a higher level. Both antigen and antibody levels increased slightly after treatment and thereafter declined to reach background levels eight weeks later. It is concluded that the ELISA has a potentially useful role in detecting both antibody and circulating antigen and that it may be successfully used in evaluating the efficacy of schistosomicides.

  20. Development of a multiplex Luminex assay for detecting swine antibodies to structural and nonstructural proteins of foot-and-mouth disease virus in Taiwan.

    Science.gov (United States)

    Chen, Tsu-Han; Lee, Fan; Lin, Yeou-Liang; Pan, Chu-Hsiang; Shih, Chia-Ni; Tseng, Chun-Hsien; Tsai, Hsiang-Jung

    2016-04-01

    Foot-and-mouth disease (FMD) and swine vesicular disease (SVD) are serious vesicular diseases that have devastated swine populations throughout the world. The aim of this study was to develop a multianalyte profiling (xMAP) Luminex assay for the differential detection of antibodies to the FMD virus of structural proteins (SP) and nonstructural proteins (NSP). After the xMAP was optimized, it detected antibodies to SP-VP1 and NSP-3ABC of the FMD virus in a single serum sample. These tests were also compared with 3ABC polypeptide blocking enzyme-linked immunosorbent assay (ELISA) and virus neutralization test (VNT) methods for the differential diagnosis and assessment of immune status, respectively. To detect SP antibodies in 661 sera from infected naïve pigs and vaccinated pigs, the diagnostic sensitivity (DSn) and diagnostic specificity (DSp) of the xMAP were 90.0-98.7% and 93.0-96.5%, respectively. To detect NSP antibodies, the DSn was 90% and the DSp ranged from 93.3% to 99.1%. The xMAP can detect the immune response to SP and NSP as early as 4 days postinfection and 8 days postinfection, respectively. Furthermore, the SP and NSP antibodies in all 15 vaccinated but unprotected pigs were detected by xMAP. A comparison of SP and NSP antibodies detected in the sera of the infected samples indicated that the results from the xMAP had a high positive correlation with results from the VNT and a 3ABC polypeptide blocking ELISA assay. However, simultaneous quantitation detected that xMAP had no relationship with the VNT. Furthermore, the specificity was 93.3-94.9% with 3ABC polypeptide blocking ELISA for the FMDV-NSP antibody. The results indicated that xMAP has the potential to detect antibodies to FMDV-SP-VP1 and NSP-3ABC and to distinguish FMDV-infected pigs from pigs infected with the swine vesicular disease virus. Copyright © 2014. Published by Elsevier B.V.

  1. Laboratory Evaluation of a Point-of-Care Downward-Flow Assay for Simultaneous Detection of Antibodies to Treponema pallidum and Human Immunodeficiency Virus

    OpenAIRE

    Herbst de Cortina, S.; Bristow, C. C.; Vargas, S. K.; Perez, D. G.; Konda, K. A.; Caceres, C. F.; Klausner, J. D.

    2016-01-01

    Combining the detection of syphilis and HIV antibodies into one point-of-care test integrates syphilis screening into already existing HIV screening programs, which may be particularly beneficial in settings such as antenatal care. Using the INSTI Multiplex downward-flow immunoassay, we tested 200 stored serum samples from high-risk patients enrolled in a longitudinal study on HIV infection and syphilis in Peruvian men who have sex with men and transgender women. This rapid assay detected HIV...

  2. Multiplex assay (Mikrogen recomBead) for detection of serum IgG and IgM antibodies to 13 recombinant antigens of Borrelia burgdorferi sensu lato in patients with neuroborreliosis

    DEFF Research Database (Denmark)

    Dessau, Ram Benny; Møller, Jens K.; Kolmos, Birte

    2015-01-01

    A multiplex-bead-based assay for the detection of serum antibodies to Borrelia burgdorferi sensu lato was evaluated. The assay contained 13 different antigens in both the IgG and the IgM assay; thus, a total of 26 measurement results were available from each sample. A total of 49 Danish patients...

  3. A human blood-brain barrier transcytosis assay reveals antibody transcytosis influenced by pH-dependent receptor binding.

    Directory of Open Access Journals (Sweden)

    Hadassah Sade

    Full Text Available We have adapted an in vitro model of the human blood-brain barrier, the immortalized human cerebral microvascular endothelial cells (hCMEC/D3, to quantitatively measure protein transcytosis. After validating the receptor-mediated transport using transferrin, the system was used to measure transcytosis rates of antibodies directed against potential brain shuttle receptors. While an antibody to the insulin-like growth factor 1 receptor (IGF1R was exclusively recycled to the apical compartment, the fate of antibodies to the transferrin receptor (TfR was determined by their relative affinities at extracellular and endosomal pH. An antibody with reduced affinity at pH5.5 showed significant transcytosis, while pH-independent antibodies of comparable affinities at pH 7.4 remained associated with intracellular vesicular compartments and were finally targeted for degradation.

  4. Optimization of fixed-permeabilized cell monolayers for high throughput micro-neutralizing antibody assays: application to the zebrafish/viral hemorrhagic septicemia virus (vhsv) model.

    Science.gov (United States)

    Chinchilla, Blanca; Encinas, Paloma; Estepa, Amparo; Coll, Julio; Gomez-Casado, Eduardo

    2013-11-01

    A new high throughput centrifugation-free method to estimate viral neutralizing antibody levels in low volumes and large numbers of plasma blood samples is described. Cell monolayers were, (i) plated on poly-d-Lys coated 96-wells, (ii) infected with viruses previously incubated with fish plasma containing antibodies, (iii) fixed with formaldehyde to increase cell recovery and avoid centrifugation steps, (iv) permeabilized with Saponin, (v) immunostained in the presence of Saponin by using a monoclonal antibody (MAb) to viral protein, (vi) digested with trypsin to detach cells from the monolayer, in the absence of Saponin to reduce damage of intracellular MAb-antigen complexes, and (vii) gated by flow cytometry using automatic 96-well batch analysis. The method was applied to the determination of plasma neutralizing antibodies from zebrafish (Danio rerio) surviving infections with viral hemorrhagic septicemia virus (VHSV) (an important rhabdovirus of salmonids). This semi-automatic, rapid and practical assay detected anti-VHSV neutralizing antibodies in the plasma (∼3 μl per fish) of 95.1% of the zebrafish surviving VHSV infections. The fixed-permeabilized monolayer (FIXPERM) micro-neutralization method might help to analyze sera/plasma from small fish under standarized high throughput conditions.

  5. Biotin-streptavidin enzyme-linked immunosorbent assay for the detection of antibodies to Campylobacter jejuni and C. coli in chickens.

    Science.gov (United States)

    Haas, B; Hinz, K H; Glünder, G

    1999-04-01

    An enzyme-linked immunosorbent assay (ELISA) was developed in a homologous system with bacterial ultrasonic-treated proteins as the antigen and antisera from chickens infected orally and subcutaneously with the strain Campylobacter jejuni serovar 6 (CJ 6). The cut-off level was determined using antisera from non-infected specific-pathogen-free chickens up to the age of 10 weeks. The suitability of the ELISA system was verified using antisera taken from chickens orally infected at the age of 4 weeks with CJ 1, 6, 28 or 36 or with Campylobacter coli serovar 28 (CC 28). The development of antibodies was monitored up to 6 weeks post-infection (p.i.). Sera from chickens infected with CJ 1, 6, 36 or CC 28 contained specific antibodies to Campylobacter, whereas in those infected with CJ 28 no specific antibodies were found. Distinct cross-reactions were observed between CJ 6, 28 and CC 28 antigens and their antisera 6 weeks p.i., while poor cross-reactions were found with antisera to CJ 1 and 28. Antibodies to strains of all heterologous serovars were successfully detected with an antigen pool comprised of CJ 1, 6 and 36 antigens. In 11 out of the 12 field sera obtained from 5- and 9-week-old broiler chickens suffering from campylobacteriosis, high specific antibody titres to Campylobacter jejuni were found.

  6. Studies to assess the biological relevance of anti-Tamm-Horsfall protein antibodies detected by direct-binding enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Hunt, J S; Groufsky, A; Lynn, K L

    1987-11-01

    1. A role has been suggested for anti-Tamm-Horsfall protein (THP) antibodies in renal disease based on the results of immunoassays of pathological sera. The putative autoantibodies have not been isolated from such sera nor have definitive inhibition studies of their binding been carried out. We have carried out such studies using rabbit anti-THP antibodies as control reagents. 2. Urinary THP prepared by salt precipitation was used to prepare four immunoabsorbent columns by covalent coupling to CNBr-activated Sepharose 4B. After washing with a variety of dissociating agents to remove any non-covalently bound subunit THP, each column was incubated with normal and immune rabbit serum. Fractions washed and eluted from columns were tested for anti-THP antibodies by enzyme-linked immunosorbent assay (ELISA) and THP antigen by radioimmunoassay, and showed NH4SCN (3 mol/l) and guanidine hydrochloride (GuHCl) (6 mol/l) equivalent and sodium dodecyl sulphate (20 g/l) to be inferior in their capacity to produce immunoabsorbent THP capable of isolating specific antibodies from immune rabbit serum. 3. The column treated with GuHCl (6 mol/l) was used further in attempts to isolate putative anti-THP antibodies from five patients, who had a history of urinary tract infections and whose sera showed strong binding by ELISA. 4. Results from direct and inhibition ELISA experiments on fractions collected after washing and elution with all sera suggested that the putative human anti-THP antibodies were of very low affinity and/or directed against non-subunit THP. 5. The pathological relevance of human anti-THP antibodies measured by ELISA remains to be established.

  7. Validation of a monoclonal antibody-based capture enzyme-linked immunosorbent assay for detection of Campylobacter fetus.

    Science.gov (United States)

    Devenish, J; Brooks, B; Perry, K; Milnes, D; Burke, T; McCabe, D; Duff, S; Lutze-Wallace, C L

    2005-11-01

    A monoclonal antibody (MAb)-based antigen capture enzyme-linked immunosorbent assay (ELISA) was compared with the routine culture methodology for the detection of Campylobacter fetus subspecies from bovine and ovine field samples inoculated into Clark's transport enrichment medium (TEM). The work was a collaboration between two different diagnostic laboratories, one in Canada and the other in England. In both labs, TEM samples were incubated for 4 days at 35 degrees C and then tested by culture and ELISA. The ELISA consisted of initial screening with MAb M1825 against C. fetus subspecies core lipopolysaccharide (LPS). All samples positive on ELISA screening were then retested by ELISA with MAb M1825 and MAbs M1177, M1183, and M1194, which recognize serotype A- and/or serotype B-specific C. fetus subspecies LPS epitopes. The Canadian samples consisted of 1,060 preputial washings from 529 bulls, of which 18 were positive by both culture and ELISA and 1,042 were negative by both methods. The English samples consisted of 321 tissue specimens, mostly stomach contents and placentas, from 190 aborted ovine and bovine fetuses. A total of 262 samples were negative by culture and ELISA, 52 samples were positive by culture and ELISA, and 7 samples were culture negative but ELISA positive. The results for all 70 culture-positive isolates were confirmed by conventional biochemical methods as C. fetus subsp. fetus, with 39 presumptively identified by the ELISA as serotype A and 30 presumptively identified as serotype B and with one sample containing isolates presumptively identified as serotype A and serotype B. A receiver operating characteristic analysis of the combined ELISA data from both countries resulted in an area under the curve of 0.997, with a sensitivity of 100% and a specificity of 99.5% relative to the results of culture. The data confirm that this ELISA method can be used as an excellent test for the screening of field samples in TEM for the presence of C. fetus

  8. Pistachio (Pistacia vera L.) Detection and Quantification Using a Murine Monoclonal Antibody-Based Direct Sandwich Enzyme-Linked Immunosorbent Assay.

    Science.gov (United States)

    Liu, Changqi; Chhabra, Guneet S; Sathe, Shridhar K

    2015-10-21

    A commercially available direct sandwich enzyme-linked immunosorbent assay (ELISA) (BioFront Technologies, Tallahassee, FL, USA) using murine anti-pistachio monoclonal antibodies (mAbs) as capture and detection antibodies was evaluated. The assay was sensitive (limit of detection = 0.09 ± 0.02 ppm full fat pistachio, linear detection range = 0.5-36 ppm, 50% maximum signal concentration = 7.9 ± 0.7 ppm), reproducible (intra- and inter-assay variability pistachio seeds subjected to autoclaving (121 °C, 15 psi, 15, 30 min), blanching (100 °C, 5, 10 min), frying (191 °C, 1 min), microwaving (500, 1000 W, 3 min), and dry roasting (140 °C, 30 min; 168 °C, 12 min). No cross-reactivity was observed in 156 food matrices, each tested at 100,000 ppm, suggesting the ELISA to be pistachio specific. The pistachio recovery ranges for spiked (10 ppm) and incurred (10-50000 ppm) food matrices were 93.1-125.6% and 35.7-112.2%, respectively. The assay did not register any false-positive or -negative results among the tested commercial and laboratory prepared samples.

  9. Simultaneous and sensitive detection of six serotypes of botulinum neurotoxin using enzyme-linked immunosorbent assay-based protein antibody microarrays

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanfeng; Lou, Jianlong; Jenko, Kathryn L.; Marks, James D.; Varnum, Susan M.

    2012-11-15

    Botulinum neurotoxins (BoNTs), produced by Clostridium botulinum, are a group of seven (A-G) immunologically distinct proteins and cause the paralytic disease botulism. These toxins are the most poisonous substances known to humans and are potential bioweapon agents. Therefore, it is necessary to develop highly sensitive assays for the detection of BoNTs in both clinical and environmental samples. In the present study, we have developed an ELISA-based protein antibody microarray for the sensitive and simultaneous detection of BoNT serotype A, B, C, D, E and F. With engineered high-affinity antibodies, the assays have sensitivities in buffer of 8 fM (1.2 pg/mL) for serotypes A and B, and 32 fM (4.9 pg/mL) for serotypes C, D, E, and F. Using clinical and environmental samples (serum and milk), the microarray is capable of detecting BoNT/A-F to the same levels as in standard buffer. Cross reactivity between assays for individual serotype was also analyzed. These simultaneous, rapid, and sensitive assays have the potential to measure botulinum toxins in a high-throughput manner in complex clinical or environmental samples.

  10. Wide dynamic range of surface-plasmon-resonance-based assay for Hepatitis-B-surface-antigen-antibody optimal detection in comparison with ELISA.

    Science.gov (United States)

    Tam, Yew Joon; Zeenathul, Nazariah Allaudin; Rezaei, Morvarid Akhavan; Mustafa, Nor Hidayah; Azmi, Mohd Lila Mohd; Bahaman, Abdul Rani; Lo, Sewn Cen; Tan, Joo Shun; Hani, Homayoun; Rasedee, Abdullah

    2016-08-10

    Limit of detection (LOD), limit of quantification (LOQ) and the dynamic range of detection of hepatitis B surface antigen antibody (anti-HBs) using surface plasmon resonance (SPR) chip-based approach with Pichia pastoris derived recombinant hepatitis B surface antigen (HBsAg) as recognition element were established through the scouting for optimal conditions for the improvement of immobilization efficiency and in the use of optimal regeneration buffer. Recombinant HBsAg was immobilized onto the sensor surface of CM5 chip at a concentration of 150 mg/L, in sodium acetate buffer at pH 4 with added 0.6% Triton X-100. Regeneration solution of 20 mM HCl was optimally found to effectively unbind analytes from the ligand, thus allowing for multiple screening cycles. A dynamic range of detection of ∼0.00098 to 0.25 mg/L was obtained and a 7-fold higher LOD, as well as a 2-fold increase in coefficient of variance (CV) of the replicated results, were shown as compared to enzyme-linked immunosorbent assay (ELISA). Evaluation of the assay for specificity showed no cross-reactivity with other antibodies tested. The ability of SPR chip-based assay and ELISA to detect anti-HBs in human serum was comparable, indicating that the SPR chip-based assay with its multiple screening capacity has greater advantage over ELISA. This article is protected by copyright. All rights reserved.

  11. Serum antibodies from a subset of horses positive for Babesia caballi by competitive enzyme-linked immunosorbent assay demonstrate a protein recognition pattern that is not consistent with infection.

    Science.gov (United States)

    Awinda, Peter O; Mealey, Robert H; Williams, Laura B A; Conrad, Patricia A; Packham, Andrea E; Reif, Kathryn E; Grause, Juanita F; Pelzel-McCluskey, Angela M; Chung, Chungwon; Bastos, Reginaldo G; Kappmeyer, Lowell S; Howe, Daniel K; Ness, SallyAnne L; Knowles, Donald P; Ueti, Massaro W

    2013-11-01

    Tick-borne pathogens that cause persistent infection are of major concern to the livestock industry because of transmission risk from persistently infected animals and the potential economic losses they pose. The recent reemergence of Theileria equi in the United States prompted a widespread national survey resulting in identification of limited distribution of equine piroplasmosis (EP) in the U.S. horse population. This program identified Babesia caballi-seropositive horses using rhoptry-associated protein 1 (RAP-1)-competitive enzyme-linked immunosorbent assay (cELISA), despite B. caballi being considered nonendemic on the U.S. mainland. The purpose of the present study was to evaluate the suitability of RAP-1-cELISA as a single serological test to determine the infection status of B. caballi in U.S. horses. Immunoblotting indicated that sera from U.S. horses reacted with B. caballi lysate and purified B. caballi RAP-1 protein. Antibody reactivity to B. caballi lysate was exclusively directed against a single ∼50-kDa band corresponding to a native B. caballi RAP-1 protein. In contrast, sera from experimentally and naturally infected horses from regions where B. caballi is endemic bound multiple proteins ranging from 30 to 50 kDa. Dilutions of sera from U.S. horses positive by cELISA revealed low levels of antibodies, while sera from horses experimentally infected with B. caballi and from areas where B. caballi is endemic had comparatively high antibody levels. Finally, blood transfer from seropositive U.S. horses into naive horses demonstrated no evidence of B. caballi transmission, confirming that antibody reactivity in cELISA-positive U.S. horses was not consistent with infection. Therefore, we conclude that a combination of cELISA and immunoblotting is required for the accurate serodiagnosis of B. caballi.

  12. Clinical implications of a new TSH-receptor-antibody-assay (DYNOtest {sup trademark} TRAKhuman) in autoimmune thyroid diseases; Klinische Implikationen eines neuen TSH-Rezeptor-Antikoerper-Assays (DYNOtest {sup trademark} TRAKhuman) bei autoimmunen Schilddruesenerkrankungen

    Energy Technology Data Exchange (ETDEWEB)

    Meller, J.; Schreivogel, I.; Becker, W. [Goettingen Univ. (Germany). Abt. fuer Nuklearmedizin; Bergmann, A.; Morgenthaler, N. [B.R.A.H.M.S Diagnostica, Berlin (Germany); Huefner, M. [Goettingen Univ. (Germany). Abt. Innere Medizin

    2000-07-01

    Aim: Conventional radioreceptor-antibody-assays (RAAs) fail in the detection of TSH-receptor antibodies (TRAKs) in 10-30% of patients with Graves' disease (GD). The aim of this study was the evaluation of the diagnostic and clinical impact of a new RRA (DYNOtest {sup trademark} TRAKhuman) which uses the human recombinant TSH-Receptor in the diagnosis of autoimmune thyroid disease. Methods: Sera from 142 consecutive patients (GD: n=50, autoimmune thyroiditis/AIT: n=92) and from 55 controls (31 patients without any thyroid disease and 14 with euthyroid goiter) were evaluated both with the DYNOtest {sup trademark} TRAKhuman-assay and a conventional RRA (TRAK-Assay {sup trademark}). Thyroid in vitro parameters and thyroid sonography were performed in all patients. Results: The DYNOtest {sup trademark} TRAK-assay was significantly superior to the conventional RRA in the diagnosis of GD (p<0,00012), especially in those who were treated by thionamides (p<0,003) and in the diagnosis of TRAK-positive patients with AIT (p<0,003). The majority of TRAK-positive AIT-patients suffered from hypothyroidism. One false positive result in patients with euthyroid goiter was found in the TRAK-Assay {sup trademark} as well as in the DYNOtest {sup trademark} TRAKhuman-Assay. Therefore the specifity of the DYNOtest {sup trademark} TRAKhuman was not inferior compared with the conventional assay. Conclusion: The DYNOtest {sup trademark} TRAK-assay is superior in the diagnostic work up of Graves' disease compared with a conventional TRAK-assay and offers an equal specifity. (orig.) [German] Ziel: Bei konventionellen Radiorezeptor-Antikoerper-Assays (RRAs) misslingt der Nachweis von TSH-Rezeptor Antikoerpern (TRAKS) bei 10-30% der immunogenen Hyperthyreosen (IH). Ziel der Studie war es, den diagnostischen und klinischen Stellenwertes eines neuen RRA (DYNOtest {sup trademark} TRAKhuman) bei autoimmunen Schilddruesenerkrankungen zu evaluieren. Methoden: Serumproben von 142

  13. Human anti-animal antibody and the interference in immunological assays%人抗动物抗体及其对免疫分析的干扰

    Institute of Scientific and Technical Information of China (English)

    杨朝国

    2001-01-01

    人抗动物抗体可引起临床不良反应,干扰动物源性抗体制剂治疗或成像,干扰免疫分析而引起假性结果。临床上可通过应用免疫抑制剂治疗和人源性抗体、聚乙二醇处理的抗体或抗体Fab段制剂等方法防止人抗动物抗体应答形成;样品预处理或分析技术的改进可消除人抗动物抗体对免疫分析的干扰。目前已设计出了多种分析技术检测人抗动物抗体,并形成了检测试剂盒,甚至床边检验试剂。%Human anti-animal antibody response may result in some adversereaction interfere with antibodies from animal therapy or imaging,and cause both false-positive and false-negative test results in immunoassays Strategies to prevent the development of human anti-animal antibody responses include immunosuppressant therapy and the use of humanized,polyethylene glycolytated antibodies,or Fab fragment of antibody agents.Sample pretreatments or assay redesign can eliminate immunoassay interference caused by human anti-animal antibodies.Currently,several assays have been designed to detect human anti-animal antibodies.There are the assays available in kit form,even a simple point-of care test.

  14. Detection of Shiga toxin-producing Escherichia coli by sandwich enzyme-linked immunosorbent assay using chicken egg yolk IgY antibodies

    Directory of Open Access Journals (Sweden)

    Yanil R Parma

    2012-06-01

    Full Text Available Enterohemorrhagic Escherichia coli (EHEC, a subset of Shiga toxin producing E. coli (STEC is associated with a spectrum of diseases that includes diarrhea, hemorrhagic colitis and a life-threatening hemolytic uremic syndrome (HUS. Regardless of serotype, Shiga toxins (Stx1 and/or Stx2 are uniformly expressed by all EHEC, and so exploitable targets for laboratory diagnosis of these pathogens. In this study, a sandwich ELISA for determination of Shiga toxin (Stx was developed using anti-Stx2 B subunit antibodies and its performance was compared with that of the Vero cell assay and a commercial immunoassay kit. Chicken IgY was used as capture antibody and a HRP-conjugated rabbit IgG as the detection antibody. The anti-Stx2B IgY was harvested from eggs laid by hens immunized with a recombinant protein fragment. Several parameters were tested in order to optimize the sandwich ELISA assay, including concentration of antibodies, type and concentration of blocking agent, and incubation temperatures. Supernatants from 42 STEC strains of different serotypes and stx variants, including stx2EDL933, stx2vha, stx2vhb, stx2g, stx1EDL933 and stx1d were tested. All Stx variants were detected by the sandwich ELISA, with a detection limit of 400 ng /ml Stx2. Twenty three strains negative for stx genes, including different bacteria species, showed no activity in Vero cell assay and produced negative results in ELISA, except for 2 strains. Our results show that anti-Stx2B IgY sandwich ELISA could be used in routine diagnosis as a rapid, specific and economic method for detection of Shiga toxin-producing E. coli.

  15. Evaluation of fully automated assays for the detection of Rubella IgM and IgG antibodies by the Elecsys(®) immunoassay system.

    Science.gov (United States)

    van Helden, Josef; Grangeot-Keros, Liliane; Vauloup-Fellous, Christelle; Vleminckx, Renaud; Masset, Frédéric; Revello, Maria-Grazia

    2014-04-01

    Screening for acute rubella infection in pregnancy is an important element of antenatal care. This study compared the sensitivity, specificity and reproducibility of two new, fully automated Elecsys(®) Rubella IgM and IgG immunoassays designed for the Elecsys 2010, Modular Analytics E170, COBAS e-411 and COBAS e-601 and e602 analytical platforms, with current assays using serum from patients with primary rubella infections, vaccinated patients, patients with potentially cross-reacting infections and on routine samples in clinical laboratories in France, Germany and Italy. Both assays showed good within-run and within-laboratory precision. A sensitivity of 79.8-96.0% was demonstrated for Elecsys IgM in primary, early acute infection, consistent with existing assays. In samples obtained from routine antenatal screening, the Elecsys Rubella IgM assay revealed high specificity (98.7-99.0%). A significantly (prubella infection was excluded, and the incidence of false positives in patients with potentially cross-reacting infections was lower with Elecsys Rubella IgM compared with other. The Elecsys Rubella IgG assay exhibited a relative sensitivity of 99.9-100.0% and specificity of 97.4-100.0% in samples from routine antenatal screening. The Elecsys Rubella IgM and IgG assays allow convenient, rapid and reliable determination of anti-rubella antibodies. Sensitivity, specificity and reproducibility were comparable with existing assay systems. Assay results were available in approximately half the time required for currently employed methods and the assays are compatible with widely used analytical platforms.

  16. Detection of antibodies to hepatitis B core antigen using the Abbott ARCHITECT anti-HBc assay: analysis of borderline reactive sera.

    Science.gov (United States)

    Ollier, Laurence; Laffont, Catherine; Kechkekian, Aurore; Doglio, Alain; Giordanengo, Valérie

    2008-12-01

    Routine use of the automated chemiluminescent microparticle immunoassay Abbott ARCHITECT anti-HBc for diagnosis of hepatitis B is limited in case of borderline reactive sera with low signal close to the cut-off index. In order to determine the significance of anti-HBc detection when borderline reactivity occurs using the ARCHITECT anti-HBc assay, a comparative study was designed. 3540 serum samples collected over a 2-month period in the hospital of Nice were examined for markers of HBV infection (HBsAg, anti-HBs and anti-HBc). One hundred seven samples with sufficient volume and with borderline reactivity by the ARCHITECT assay were tested by two other anti-HBc assays, a microparticle enzyme immunoassay (MEIA, AxSYM Core, Abbott Laboratories, IL, USA) and an enzyme linked fluorescent assay (ELFA, VIDAS Anti-HBc Total II, bioMérieux, Lyon, France). Only 46 samples were confirmed by the AxSYM and the VIDAS assays. Additional serological information linked to patient history showed that the remaining samples (61) were false positives (11), had low titer of anti-HBc antibodies (13), or were inconclusive (37). This comparative study highlighted the existence of a grey zone around the cut-off index. Confirmative results through a different immunoassay are needed to confirm the diagnosis of HBV on borderline reactive sera using the ARCHITECT anti-HBc assay.

  17. Monoclonal antibody-based dipstick assay: a reliable field applicable technique for diagnosis of Schistosoma mansoni infection using human serum and urine samples.

    Science.gov (United States)

    Demerdash, Zeinab; Mohamed, Salwa; Hendawy, Mohamed; Rabia, Ibrahim; Attia, Mohy; Shaker, Zeinab; Diab, Tarek M

    2013-02-01

    A field applicable diagnostic technique, the dipstick assay, was evaluated for its sensitivity and specificity in diagnosing human Schistosoma mansoni infection. A monoclonal antibody (mAb) against S. mansoni adult worm tegumental antigen (AWTA) was employed in dipstick and sandwich ELISA for detection of circulating schistosome antigen (CSA) in both serum and urine samples. Based on clinical and parasitological examinations, 60 S. mansoni-infected patients, 30 patients infected with parasites other than schistosomiasis, and 30 uninfected healthy individuals were selected. The sensitivity and specificity of dipstick assay in urine samples were 86.7% and 90.0%, respectively, compared to 90.0% sensitivity and 91.7% specificity of sandwich ELISA. In serum samples, the sensitivity and specificity were 88.3% and 91.7% for dipstick assay vs. 91.7% and 95.0% for sandwich ELISA, respectively. The diagnostic efficacy of dipstick assay in urine and serum samples was 88.3% and 90.0%, while it was 90.8% and 93.3% for sandwich ELISA, respectively. The diagnostic indices of dipstick assay and ELISA either in serum or in urine were statistically comparable (P>0.05). In conclusion, the dipstick assay offers an alternative simple, rapid, non-invasive technique in detecting CSA or complement to stool examinations especially in field studies.

  18. Highly sensitive enzyme-free immunosorbent assay for porcine circovirus type 2 antibody using Au-Pt/SiO2 nanocomposites as labels.

    Science.gov (United States)

    Wu, Long; Yin, Wenmin; Tang, Kun; Shao, Kang; Li, Qin; Wang, Pan; Zuo, Yunpeng; Lei, Xiaomin; Lu, Zhicheng; Han, Heyou

    2016-08-15

    Improving the performance of conventional enzyme-linked immunosorbent assay (ELISA) is of great importance to meet the demand of early clinical diagnosis of various diseases. Herein, we report a feasible enzyme-free immunosorbent assay (EFISA) system using antibody conjugated Au-Pt/SiO2 nanocomposites (APS NCs) as labels. In this system, Au-Pt/SiO2 nanospheres (APS NPs) were first synthesized by wet chemical method and exhibited intrinsic peroxidase and catalase-like activity with excellent water-solubility. Then APS NCs were utilized as labels to replace HRP conjugated antibody, and Fe3O4 magnetic beads (MBs) to entrap the analyte. To discuss the performance of EFISA system, Human IgG was served as a model analyte, and porcine circovirus type 2 (PCV2) serums as real samples. The system boosted the detection limit of HIgG to 75pgmL(-1) with a RSD below 5%, a 264-fold improvement as compared with conventional ELISA. This is the first time that APS NCs have been used and successfully optimized for the sensitive dilution detection of PCV2 antibody (5:10(7)) in ELISA. Besides, APS NCs have advantages related to low cost, easy preparation, good stability and tunable catalytic activity, which make them a potent enzyme mimetic candidate and may find potential applications in bioassays and clinical diagnostics.

  19. Production of monoclonal antibody for okadaic acid and its utilization in an ultrasensitive enzyme-linked immunosorbent assay and one-step immunochromatographic strip.

    Science.gov (United States)

    Liu, Biing-Hui; Hung, Chun-Tse; Lu, Chuan-Chen; Chou, Hong-Non; Yu, Feng-Yih

    2014-02-12

    Okadaic acid (OA) is a common marine biotoxin that accumulates in bivalves and causes diarrhetic shellfish poisoning (DSP). This study generated a monoclonal antibody (mAb) specific to OA from a hybridoma cell line, 6B1A3, which was obtained by fusion of myeloma cells (P3/NS1/1-AG4-1) with spleen cells isolated from a BALB/c mouse immunized with OA-γ-globulin. The 6B1A3 mAb belongs to the immunoglobulin G1 (κ chain) isotype. Both competitive direct and indirect enzyme-linked immunosorbent assays (ELISAs) were established for characterization of the antibody. The concentrations causing 50% inhibition of binding of OA-horseradish peroxidase to the antibody by OA were calculated to be 0.077 ng/mL in the cdELISA. A rapid and sensitive mAb-based gold nanoparticle immunochromatographic strip was also established. This proposed strip has a detection limit of 5 ng/mL for OA and can be finished in 10 min. Extensive analyses of 20 seafood samples with ELISA revealed that 10 were slightly contaminated with OA, with a mean concentration of 0.892 ng/g. Analysis of OA in shellfish samples showed that data acquired by the immunochromatographic strip agreed well with those acquired by the ELISA. The mAb-based ELISA and immunochromatographic strip assay developed in this study have adequate sensitivity and accuracy for rapid screening of OA in shellfish samples.

  20. Development of an enzyme-linked immunosorbent assay for the detection of isomiroestrol, an identical marker, in White Kwao Krua using a monoclonal antibody.

    Science.gov (United States)

    Kitisripanya, Tharita; Jutathis, Kamonthip; Inyai, Chadathorn; Komaikul, Jukrapun; Udomsin, Orapin; Tanaka, Hiroyuki; Putalun, Waraporn

    2017-04-15

    Pueraria candollei var. mirifica or White Kwao Krua (WKK) is a phytoestrogen-rich plant widely used among women to improve climacteric symptoms. Additionally, the tuberous roots of this plant have been added as an active ingredient for skin rejuvenation and breast enlargement effects in various functional foods. However, most of the products on the market containing WKK have not been sufficiently standardized with respect to the active compound or identical marker. To control the quality of these plant materials, an enzyme-linked immunosorbent assay (ELISA) using anti-isomiroestrol antibodies was established for the determination of isomiroestrol, an identical marker in WKK. Polyclonal and monoclonal antibodies against isomiroestrol were generated and their specificity characterized in this study. Monoclonal antibody 12C1 showed higher specificity to isomiroestrol and was thus selected to develop the ELISA. Based on the validation analysis and the tested performance of the developed ELISA in variably sourced WKK samples, the assay can provide an alternative approach that is reliable and highly sensitive for the quantitative analysis of isomiroestrol in plant.

  1. Antibody responses to Campylobacter infections determined by an enzyme-linked immunosorbent assay: 2-year follow-up study of 210 patients.

    Science.gov (United States)

    Strid, M A; Engberg, J; Larsen, L B; Begtrup, K; Mølbak, K; Krogfelt, K A

    2001-03-01

    An enzyme-linked immunosorbent assay (ELISA) was adapted to measure immunoglobulin G (IgG), IgM, and IgA classes of human serum antibody to Campylobacter jejuni and Campylobacter coli. Heat-stable antigen, a combination of C. jejuni serotype O:1,44 and O:53 in the ratio 1:1, was used as a coating antigen in the ELISA test. A total of 631 sera from 210 patients with verified Campylobacter enteritis were examined at various intervals after infection, and a control group of 164 sera were tested to determine the cut-off for negative results. With a 90th percentile of specificity, IgG, IgM, and IgA showed a sensitivity of 71, 60, and 80%, respectively. By combining all three antibody classes, the sensitivity was 92% within 35 days after infection, whereas within 90 days after infection, a combined sensitivity of 90% was found (IgG 68%, IgM 52%, and IgA 76%). At follow-up of the patients, IgG antibodies were elevated 4.5 months after infection but exhibited a large degree of variation in antibody decay profiles. IgA and IgM antibodies were elevated during the acute phase of infection (up to 2 months from onset of infection). The antibody response did not depend on Campylobacter species or C. jejuni serotype, with the important exception of response to C. jejuni O:19, the serotype most frequently associated with Guillain-Barré syndrome. All of the patients infected with this serotype had higher levels of both IgM (P = 0.006) and IgA (P = 0.06) compared with other C. jejuni and C. coli serotypes.

  2. Performance of a rapid, on-site human immunodeficiency virus antibody assay in a public health setting.

    Science.gov (United States)

    Kassler, W J; Haley, C; Jones, W K; Gerber, A R; Kennedy, E J; George, J R

    1995-11-01

    Rapid, on-site human immunodeficiency virus (HIV) testing has the potential to improve the delivery of prevention services in publicly funded counseling and testing sites. The Single Use Diagnostic System (SUDS) HIV-1 is the only rapid enzyme immunoassay (EIA) approved for diagnostic use in the United States. To evaluate the feasibility of using SUDS in public clinics and to validate the test's performance in a public health laboratory, we conducted blinded SUDS testing on plasma sent for HIV testing. From 19 March through 30 June 1993, 1,923 consecutive samples from a sexually transmitted diseases clinic and an HIV counseling and testing clinic were tested on site with SUDS. Tests done in the first two weeks with a malfunctioning centrifuge n = 402) and those done when there were excessively high temperatures in the laboratory (n = 53) were analyzed separately. Of 1,466 tests, 39 were positive by both SUDS and EIA (with Western blot [immunoblot] confirmation) and 7 were SUDS positive and EIA negative. Western blotting was used as the "gold standard" to adjudicate these discrepancies. There were no SUDS-negative and EIA-positive tests. Compared with that of EIA (with Western blot confirmation), the sensitivity of SUDS was 100% (95% confidence interval, 88.8 to 100%) and the specificity was 99.5% (95% confidence interval, 98.9 to 99.8%). The positive predictive value of SUDS was 88% in the STD clinic and 81% in the HIV counseling and testing clinic. There was a 7.7-fold increase in false positives, from 0.48 to 3.7%, when there was inadequate centrifugation and when the temperature exceeded the manufacturer's recommendations. Rapid, on-site HIV testing by the SUDS assay is feasible and practical in public health settings. The test can be performed accurately, at reasonable cost, and within the time frame of a typical clinic visit. Caution should be used, however, as two conditions adversely affected the accuracy of this test: inadequate specimen preparation and

  3. [Enzyme-linked immunosorbent assay (ELISA) for detection of antibodies to Salmonella Typhi lipopolysaccharide O and capsular polysaccharide Vi antigens in persons from outbreak of typhoid fever].

    Science.gov (United States)

    Rastawicki, Waldemar; Kałużewski, Stanisław

    2015-01-01

    The laboratory diagnosis of typhoid fever is dependent upon either isolation of S. Typhi from a clinical sample or the detection of raised titers of serum antibodies in the Widal test or the passive hemagglutination assay (PHA). In this study we evaluated the usefulness of ELISA for detection of antibodies to S. Typhi lipopolysaccharide O and capsular polysaccharide Vi antigens in the sera of persons from outbreak of typhoid fever. Fifteen serum samples from patients with laboratory confirmed typhoid fever and 140 sera from persons suspected for contact with typhoid fever patients from outbreak in 1974/75 in Poland were tested by ELISA. Additionally, as the control group, we tested 115 sera from blood donors for the presence of S. Typhi anti-LPS and anti-Vi antibodies. Anti-LPS and anti-Vi antibodies were detected in 80% and 53.3% of sera obtained from patients with laboratory confirmed typhoid fever, respectively. The high percentages of positive results in ELISA were also noted in the group of persons suspected for contact with typhoid fever patients (51.4% and 45%) but not in the group of blood donors (7.8% and 6.1%, respectively). The ELISA could be a useful tool for the serological diagnosis of typhoid fever in patients who have clinical symptoms but are culture negative, especially during massive outbreaks of typhoid fever.

  4. The effect on kaolin adsorption of serum on the virus neutralization and enzyme-linked immunosorbent assays of antibody to bovine herpesvirus 1.

    Science.gov (United States)

    Darcel, C L; Kozub, G C

    1984-01-01

    Two procedures have been used for measuring antibody titres to bovine herpes virus 1 (BHV1): the serum neutralization (SN) test and enzyme-linked immunosorbent assay (ELISA). One hundred and thirty-two sera selected for their low SN titres were tested both unadsorbed and after adsorption with kaolin to determine the effect of kaolin on the titres. With ELISA, the titres of unadsorbed and kaolin adsorbed were not significantly different but with the SN test many treated sera, originally with weak positive titres, became negative after kaolin adsorption. Thus, if the ELISA results are specific for BHV1 antibody then the SN test findings suggest that treatment of sera with kaolin, rather than removing a viral inhibitor, removes a substance from the serum which potentiates SN antibody. This in turn indicates that low SN titres (reciprocal of titre less than or equal to 4, for instance) are probably specific for BHV1 SN antibody whether or not they are abolished by kaolin treatment of the serum.

  5. Development of an antigen-capture enzyme-linked immunosorbent assay using monoclonal antibodies for detecting H6 avian influenza viruses.

    Science.gov (United States)

    Chen, Yi-Tung; Tsao, Zak; Chang, Shu-Ting; Juang, Ron-Huay; Wang, Lih-Chiann; Chang, Chung-Ming; Wang, Ching-Ho

    2012-06-01

    The H6 subtype of avian influenza virus (AIV) infection occurs frequently in wild and domestic birds. AIV antigen detection is preferred for controlling AIV as birds are infected before they produce antibodies. The purpose of this study was to develop an early diagnostic method for AIV detection. Six monoclonal antibodies (mAbs) developed from a field H6N1 AIV strain were tested for their ability to bind to viruses. The two that showed the greatest binding ability to AIVs were used for antigen detection. An antigen-capture enzyme-linked immunosorbent assay (ELISA) to detect H6 AIVs was developed using these mAbs. One mAb was coated onto an ELISA plate as the capture antibody. The other mAb was used as the detector antibody after labeling with horseradish peroxidase. The antigen-capture ELISA detected H6N1 AIVs but not H5 AIVs, human H1N1, H3N2 influenza or other viruses. This antigen-capture ELISA could be used to specifically detect H6N1 AIV.

  6. Indirect enzyme-antibody sandwich enzyme-linked immunosorbent assay for quantification of TAXI and XIP type xylanase inhibitors in wheat and other cereals.

    Science.gov (United States)

    Beaugrand, Johnny; Gebruers, Kurt; Ververken, Cedric; Fierens, Ellen; Dornez, Emmie; Goddeeris, Bruno M; Delcour, Jan A; Courtin, Christophe M

    2007-09-19

    To quantify Triticum aestivum xylanase inhibitor (TAXI) and xylanase inhibiting protein (XIP) type proteins in cereals in general and wheat ( T. aestivum) in particular, a robust enzyme-linked immunosorbent assay (ELISA) using an uncommon enzyme-antibody sandwich format was developed. Bacillus subtilis glycoside hydrolase family (GH) 11 and Aspergillus oryzae GH 10 xylanases were selected for coating ELISA plate wells to capture TAXI and XIP, respectively, prior to probing with antibodies. The detection threshold of the developed ELISA was much lower than that of the currently used xylanase inhibitor assay and the recently described Western blot approach. Because of its broad dynamic range (TAXI, 30-600 ng/mL, and XIP, 3-60 ng/mL), one proper standard extract dilution can be used for analyzing different wheat varieties, whereas for the currently used colorimetric assay, often different dilutions need to be analyzed. The TAXI ELISA for wheat was successfully adapted for barley ( Hordeum vulgare) and could also be used for other cereals.

  7. Specific Capture of Peptide-Receptive Major Histocompatibility Complex Class I Molecules by Antibody Micropatterns Allows for a Novel Peptide-Binding Assay in Live Cells.

    Science.gov (United States)

    Dirscherl, Cindy; Palankar, Raghavendra; Delcea, Mihaela; Kolesnikova, Tatiana A; Springer, Sebastian

    2017-02-02

    Binding assays with fluorescently labeled ligands and recombinant receptor proteins are commonly performed in 2D arrays. But many cell surface receptors only function in their native membrane environment and/or in a specific conformation, such as they appear on the surface of live cells. Thus, receptors on live cells should be used for ligand binding assays. Here, it is shown that antibodies preprinted on a glass surface can be used to specifically array a peptide receptor of the immune system, i.e., the major histocompatibility complex class I molecule H-2K(b) , into a defined pattern on the surface of live cells. Monoclonal antibodies make it feasible to capture a distinct subpopulation of H-2K(b) and hold it at the cell surface. This patterned receptor enables a novel peptide-binding assay, in which the specific binding of a fluorescently labeled index peptide is visualized by microscopy. Measurements of ligand binding to captured cell surface receptors in defined confirmations apply to many problems in cell biology and thus represent a promising tool in the field of biosensors.

  8. HIV中和抗体评价方法研究进展%Research progress evaluation assay in HIV neutralizing antibody

    Institute of Scientific and Technical Information of China (English)

    聂建辉; 王佑春

    2012-01-01

    诱导广谱有效的中和抗体被认为是预防性疫苗成功的关键,HIV中和抗体检测方法的建立和标准化为HIV疫苗评价和设计提供指导,也为不同HIV疫苗的比较提供了平台.本文从方法的建立、假病毒株的选择、评价标准的制定、评价策略的确定、该方法在HⅣ其它研究领域的应用等方面,对目前应用最广泛的以假病毒为基础的中和抗体评价方法进行了综述.%It is well -known that induction of effective broad -spectrum neutralizing antibodies is the key for successful prophylactic vaccines. Establishment and standardization of the HIV neutralizing antibody assays will assist the vaccine design and provide a platform to compare the vaccines from different laboratories. In this paper,we reviewed the most acceptable pseudovirus -based neutralization assay in following aspects,establishment of the assay,principles for pseudovirus selection,determination of the evaluation criteria and strategy,and applications in other fields.

  9. Development and application of a double-antigen sandwich enzyme-linked immunosorbent assay for detection of antibodies to porcine circovirus 2.

    Science.gov (United States)

    Ge, Meng; Luo, Wei; Jiang, Daliang; Li, Runcheng; Zhao, Wenwei; Chen, Guoliang; Yang, Xingdong; Yu, Xinglong

    2012-09-01

    A double-antigen sandwich enzyme-linked immunosorbent assay (ELISA) is described for detection of porcine circovirus 2 (PCV2) antibodies using the well-characterized recombinant PCV2 capsid protein. In a comparative test of 394 pig sera against an indirect immunofluorescence (IIF) test and a commercial ELISA kit (also based on the recombinant PCV2 capsid protein), the results showed that the diagnostic sensitivity, specificity, and accuracy of the assay were, respectively, 90.61, 94.02, and 91.62% compared with IIF and 94.38, 95.28, and 94.67% compared with the commercial ELISA kit. Assay of 12 PCV-free pigs over a 5-week period produced only PCV2-negative titers by all 3 methods. These results and the seroprofiles of 4 pig farms obtained by both the commercial ELISA kit and the double-antigen sandwich ELISA indicate that the sandwich ELISA is a reliable method for detection of antibodies to PCV2. Additionally, the method described here permits the use of undiluted test serum samples simultaneously loaded with horseradish peroxidase (HRP)-conjugated antigen into the test well, and the complete test procedure can be performed in less than 90 min. This double-antigen sandwich ELISA should be a useful tool to aid swine industry professionals in deciding the intervention strategies for the control of PCV2-associated diseases.

  10. An undetectable source of technical error that could lead to false negative results in enzyme linked immunosorbent assay of antibodies to HIV-1.

    Science.gov (United States)

    Wiltbank, T B; McCarroll, D R; Wartick, M G

    1989-01-01

    Since the institution of routine testing for antibodies to Human Immunodeficiency Virus (HIV) using the enzyme-linked immunosorbent assay (ELISA), the specificity and sensitivity of this assay system has received significant scrutiny. During previous use of this methodology, we have quantified rates of false biological positive results using commercial kit assays in a normal donor population. In this study, we have identified a potential source for false negative results. Using multiple lots of two different commercial ELISA kits, the absorbance readings at the test end point could not differentiate between normal non-reactive donor samples and blanks containing no sample. These results occur using normal donor samples, even though the assays could distinguish between blank wells and the manufacturers' "normal controls", provided with the assay. Our findings suggest that a technical pipetting error is presently undetectable, either visually or by statistical methods, and could permit an untested, potentially HIV-1 positive, unit to be released into the transfusable blood supply. A possible solution is suggested.

  11. A novel rabbit immunospot array assay on a chip allows for the rapid generation of rabbit monoclonal antibodies with high affinity.

    Directory of Open Access Journals (Sweden)

    Tatsuhiko Ozawa

    Full Text Available Antigen-specific rabbit monoclonal antibodies (RaMoAbs are useful due to their high specificity and high affinity, and the establishment of a comprehensive and rapid RaMoAb generation system has been highly anticipated. Here, we present a novel system using immunospot array assay on a chip (ISAAC technology in which we detect and retrieve antigen-specific antibody-secreting cells from the peripheral blood lymphocytes of antigen-immunized rabbits and produce antigen-specific RaMoAbs with 10(-12 M affinity within a time period of only 7 days. We have used this system to efficiently generate RaMoAbs that are specific to a phosphorylated signal-transducing molecule. Our system provides a new method for the comprehensive and rapid production of RaMoAbs, which may contribute to laboratory research and clinical applications.

  12. Application of the Ceditest FMDV type O and FMDV-NS enzyme-linked immunosorbent assays for detection of antibodies against Foot-and-mouth disease virus in selected livestock and wildlife species in Uganda

    DEFF Research Database (Denmark)

    Ayebazibwe, Chrisostom; Mwiine, Frank Norbert; Balinda, Sheila Nina

    2012-01-01

    Diagnosis and control of Foot-and-mouth disease virus (FMDV) requires rapid and sensitive diagnostic tests. Two antibody enzyme-linked immunosorbent assay (ELISA) kits, Ceditest FMDV-NS for the detection of antibodies against the nonstructural proteins of all FMDV serotypes and Ceditest FMDV type...

  13. Performance of an automated solid-phase red cell adherence system compared with that of a manual gel microcolumn assay for the identification of antibodies eluted from red blood cells.

    Science.gov (United States)

    Finck, R H; Davis, R J; Teng, S; Goldfinger, D; Ziman, A F; Lu, Q; Yuan, S

    2011-01-01

    IgG antibodies coating red blood cells (RBCs) can be removed by elution procedures and their specificity determined by antibody identification studies. Although such testing is traditionally performed using the tube agglutination assay, prior studies have shown that the gel microcolumn (GMC) assay may also be used with comparable results. The purpose of this study was to compare an automated solid-phase red cell adherence (SPRCA) system with a GMC assay for the detection of antibodies eluted from RBCs. Acid eluates from 51 peripheral blood (PB) and 7 cord blood (CB) samples were evaluated by both an automated SPRCA instrument and a manual GMC assay. The concordance rate between the two systems for peripheral RBC samples was 88.2 percent (45 of 51), including cases with alloantibodies (n = 8), warm autoantibodies (n = 12), antibodies with no identifiable specificity (n = 2), and negative results (n = 23). There were six discordant cases, of which four had alloantibodies (including anti-Jka, -E, and -e) demonstrable by the SPRCA system only. In the remaining 2 cases, anti-Fya and antibodies with no identifiable specificity were demonstrable by the GMC assay only. All seven CB specimens produced concordant results, showing anti-A (n = 3), -B (n = 1), maternal anti-Jka (n = 2), or a negative result (n = 1). Automated SPRCA technology has a performance that is comparable with that of a manual GMC assay for identifying antibodies eluted from PB and CB RBCs.

  14. Downfall of the current antibody correlates of influenza vaccine response in yearly vaccinated subjects: Toward qualitative rather than quantitative assays.

    Science.gov (United States)

    Cagigi, Alberto; Cotugno, Nicola; Rinaldi, Stefano; Santilli, Veronica; Rossi, Paolo; Palma, Paolo

    2016-02-01

    Response to seasonal influenza vaccination is currently evaluated by antibody correlates that estimate vaccine seroconversion as well as immune protection. These correlates rely on the general dogmas surrounding seasonal influenza vaccination; that is, that vaccine-induced antibodies would exclusively generate immunity to influenza vaccine strains and that protective immunity would wane before the next season. Here, we summarize recently reported data on immunity to seasonal influenza in healthy individuals and rediscuss results on yearly vaccinated pediatric immunocompromised patients that together highlight the need for revision of the current correlates of vaccine response to shift from quantitative to qualitative measurements.

  15. Varicella Zoster Virus Myelitis in Two Elderly Patients: Diagnostic Value of Nested Polymerase Chain Reaction Assay and Antibody Index for Cerebrospinal Fluid Specimens

    Directory of Open Access Journals (Sweden)

    Teruyuki Takahashi

    2013-04-01

    Full Text Available Background: Myelitis is one of the rarest neurological complications of the varicella zoster virus (VZV infection. Focal muscle weakness with or without sensory disturbance occurs in approximately 5% of the cases after acute VZV infection, with complete recovery in 50-70%. Case Presentation: This report describes two rare cases of elderly patients with VZV myelitis secondary to dermatomal zoster rash. Patient 1 was a 79-year-old woman who developed paraplegia, numbness and decreased sensation in the left arm and below thoracic (Th-10 after sacral zoster. Spinal cord MRI showed a high-signal-intensity lesion at the cervical spinal nerve 2 on a T2-weighted image. Patient 2 was a 73-year-old man who developed right flaccid leg weakness and urinary retention after right dorsal Th 5-8 zoster. Spinal cord MRI showed a high-signal-intensity lesion at Th 3-4 on a T2-weighted image. In both cases, although the conventional single polymerase chain reaction (PCR assays all showed negative results, the original nested PCR assay detected VZV DNA in the cerebrospinal fluid (CSF specimen collected on admission. In addition, the anti-VZV IgG antibody by enzyme immunoassay and antibody index were elevated in the CSF specimens during the clinical courses of both patients. On the basis of these findings, both patients were diagnosed with VZV myelitis and were treated with high-dose acyclovir and corticosteroid. This combined treatment was appropriate and effective for the improvement of their functional outcomes. Conclusion: The detection of VZV DNA in CSF by nested PCR assay and the evaluation of the antibody index to VZV had significant diagnostic value.

  16. Varicella zoster virus myelitis in two elderly patients: diagnostic value of nested polymerase chain reaction assay and antibody index for cerebrospinal fluid specimens.

    Science.gov (United States)

    Takahashi, Teruyuki; Tamura, Masato; Miki, Kenji; Yamaguchi, Mai; Kanno, Akira; Nunomura, Satoshi; Ra, Chisei; Tamiya, Takashi; Kamei, Satoshi; Takasu, Toshiaki

    2013-01-01

    Myelitis is one of the rarest neurological complications of the varicella zoster virus (VZV) infection. Focal muscle weakness with or without sensory disturbance occurs in approximately 5% of the cases after acute VZV infection, with complete recovery in 50-70%. This report describes two rare cases of elderly patients with VZV myelitis secondary to dermatomal zoster rash. Patient 1 was a 79-year-old woman who developed paraplegia, numbness and decreased sensation in the left arm and below thoracic (Th)-10 after sacral zoster. Spinal cord MRI showed a high-signal-intensity lesion at the cervical spinal nerve 2 on a T2-weighted image. Patient 2 was a 73-year-old man who developed right flaccid leg weakness and urinary retention after right dorsal Th 5-8 zoster. Spinal cord MRI showed a high-signal-intensity lesion at Th 3-4 on a T2-weighted image. In both cases, although the conventional single polymerase chain reaction (PCR) assays all showed negative results, the original nested PCR assay detected VZV DNA in the cerebrospinal fluid (CSF) specimen collected on admission. In addition, the anti-VZV IgG antibody by enzyme immunoassay and antibody index were elevated in the CSF specimens during the clinical courses of both patients. On the basis of these findings, both patients were diagnosed with VZV myelitis and were treated with high-dose acyclovir and corticosteroid. This combined treatment was appropriate and effective for the improvement of their functional outcomes. The detection of VZV DNA in CSF by nested PCR assay and the evaluation of the antibody index to VZV had significant diagnostic value.

  17. Initial development and preliminary evaluation of a multiplex bead assay to detect antibodies to Ehrlichia canis, Anaplasma platys, and Ehrlichia chaffeensis outer membrane peptides in naturally infected dogs from Grenada, West Indies.

    Science.gov (United States)

    Wilkerson, Melinda J; Black, Kelley E; Lanza-Perea, Marta; Sharma, Bhumika; Gibson, Kathryn; Stone, Diana M; George, Anushka; Nair, Arathy D S; Ganta, Roman R

    2017-01-01

    Tick-borne bacteria, Ehrlichia canis, Anaplasma platys, and Ehrlichia chaffeensis are significant pathogens of dogs worldwide, and coinfections of E. canis and A. platys are common in dogs on the Caribbean islands. We developed and evaluated the performance of a multiplex bead-based assay to detect antibodies to E. canis, A. platys, and E. chaffeensis peptides in dogs from Grenada, West Indies, where E. canis and A. platys infections are endemic. Peptides from outer membrane proteins of P30 of E. canis, OMP-1X of A. platys, and P28-19/P28-14 of E. chaffeensis were coupled to magnetic beads. The multiplex peptide assay detected antibodies in dogs experimentally infected with E. canis and E. chaffeensis, but not in an A. platys experimentally infected dog. In contrast, the multiplex assay and an in-house enzyme-linked immunosorbent assay (ELISA) detected A. platys antibodies in naturally infected Grenadian dogs. Following testing of 104 Grenadian canine samples, multiplex assay results had good agreement with commercially available ELISA and immunofluorescent assay for E. canis antibody-positive dogs ( K values of 0.73 and 0.84), whereas A. platys multiplex results had poor agreement with these commercial assays ( K values of -0.02 and 0.01). Prevalence of seropositive E. canis and A. platys Grenadian dogs detected by the multiplex and commercial antibody assays were similar to previous reports. Although the multiplex peptide assay performed well in detecting the seropositive status of dogs to E. canis and had good agreement with commercial assays, better antigen targets are necessary for the antibody detection of A. platys.

  18. Anti-amebic antibody activity in patients, determined with antigens prepared from virulent parasites (indirect hemagglutination assay and enzyme-linked immunosorbent assay).

    Science.gov (United States)

    Israeli, Eitan; Talis, Batya; Peled, Nehama; Snier, Rachella; El-On, Joseph

    2007-09-01

    The serology of amebiasis is affected by low sensitivity and specificity. To evaluate the advantage of the indirect hemagglutination assay and enzyme-linked immunosorbent assay in the diagnosis of amebiasis, using Entamoeba histolytica soluble antigen (macerated amebic antigens) prepared from four different virulent isolates, continuously cultivated in the presence of the original enteric bacteria. Using IHA and ELISA with MAA antigen we examined 147 sera samples from patients with gastrointestinal symptoms, and 11 sera from amebiasis cases (confirmed by microscopy and copro-antigen ELISA). Of 104 of the 147 (70.7%) symptomatic cases that were amebiasis positive by IHA, 81 (55.1%) were positive by MAA-ELISA. In addition, of 11 amebiasis cases confirmed by microscopy and copro-antigen ELISA, 7 (64%) were amebiasis positive by both tests. Four species of bacteria were isolated from the ameba cultures: Escherichia coli, Morganella morganii, Proteus mirabilis, and Streptococcus lactis. Elimination of the bacteria from the cultures by an antibiotics cocktail containing gentamicin, imipenem, piperacillin-tazobactam and vancomycin was the preferred method. Absorption of patients' sera to bacterial antigen prior to serological analysis had only a marginal effect. These results indicate a correlation of 61% between the ELISA developed in this study and the IHA tests in the diagnosis of amebiasis.

  19. Evaluation of classical swine fever virus antibody detection assays with an emphasis on the differentiation of infected from vaccinated animals

    DEFF Research Database (Denmark)

    Schroeder, S.; von Rosen, Tanya; Blome, S.

    2012-01-01

    vaccinated animals (DIVA). The Chekit* CSF-Sero and the HerdChek* CSFV Ab, both of which detect antibodies against the E2 protein of classical swine fever virus (CSFV), had the highest sensitivity. Both tests were practicable and showed good reproducibility. Comparable sensitivity was shown by the Chekit...

  20. Accurate antemortem diagnosis of equine protozoal myeloencephalitis (EPM) based on detecting intrathecal antibodies against Sarcocystis neurona using the SnSAG2 and SnSAG4/3 ELISAs.

    Science.gov (United States)

    Reed, S M; Howe, D K; Morrow, J K; Graves, A; Yeargan, M R; Johnson, A L; MacKay, R J; Furr, M; Saville, W J A; Williams, N M

    2013-01-01

    Recent work demonstrated the value of antigen-specific antibody indices (AI and C-value) to detect intrathecal antibody production against Sarcocystis neurona for antemortem diagnosis of equine protozoal myeloencephalitis (EPM). The study was conducted to assess whether the antigen-specific antibody indices can be reduced to a simple serum : cerebrospinal fluid (CSF) titer ratio to achieve accurate EPM diagnosis. Paired serum and CSF samples from 128 horses diagnosed by postmortem examination. The sample set included 44 EPM cases, 35 cervical-vertebral malformation (CVM) cases, 39 neurologic cases other than EPM or CVM, and 10 non-neurologic cases. Antibodies against S. neurona were measured in serum and CSF pairs using the SnSAG2 and SnSAG4/3 (SnSAG2, 4/3) ELISAs, and the ratio of each respective serum titer to CSF titer was determined. Likelihood ratios and diagnostic sensitivity and specificity were calculated based on serum titers, CSF titers, and serum : CSF titer ratios. Excellent diagnostic sensitivity and specificity was obtained from the SnSAG2, 4/3 serum : CSF titer ratio. Sensitivity and specificity of 93.2 and 81.1%, respectively, were achieved using a ratio cutoff of ≤100, whereas sensitivity and specificity were 86.4 and 95.9%, respectively, if a more rigorous cutoff of ≤50 was used. Antibody titers in CSF also provided good diagnostic accuracy. Serum antibody titers alone yielded much lower sensitivity and specificity. The study confirms the value of detecting intrathecal antibody production for antemortem diagnosis of EPM, and they further show that the antigen-specific antibody indices can be reduced in practice to a simple serum : CSF titer ratio. Copyright © 2013 by the American College of Veterinary Internal Medicine.

  1. Clinical implications of measuring drug and anti-drug antibodies by different assays when optimizing infliximab treatment failure in Crohn's disease

    DEFF Research Database (Denmark)

    Steenholdt, Casper; Bendtzen, Klaus; Brynskov, Jørn;

    2014-01-01

    classifications. The four different assays did not differ in terms of the ability to predict response to interventions defined by the algorithm. CONCLUSIONS: Despite variable analytical properties, common assays result in similar classifications and interventions in patients with IFX treatment failure......OBJECTIVES: Cost-effective guidance of therapeutic strategy in Crohn's disease patients with secondary infliximab (IFX) treatment failure may be achieved by serum IFX and anti-IFX antibody (Ab) measurements by radioimmunoassay (RIA). This study investigated implications of using other techniques...... on classification of underlying mechanism for treatment failure in most cases (79-94%). The majority (74-88%) failed IFX owing to pharmacodynamic problems, or had noninflammatory pathophysiology for symptoms resembling relapse. Applied threshold for therapeutic vs. subtherapeutic IFX level influenced...

  2. Development of an Antigen-DNAzyme Based Probe for a Direct Antibody-Antigen Assay Using the Intrinsic DNAzyme Activity of a Daunomycin Aptamer

    Directory of Open Access Journals (Sweden)

    Noorsharmimi Omar

    2013-12-01

    Full Text Available G-Quadruplex (G-4 structures are formed when G-rich DNA sequences fold into intra- or intermolecular four-stranded structures in the presence of metal ions. G-4-hemin complexes are often effective peroxidase-mimicking DNAzymes that are applied in many detection systems. This work reports the application of a G-rich daunomycin-specific aptamer for the development of an antibody-antigen detection assay. We investigated the ability of the daunomycin aptamer to efficiently catalyze the hemin-dependent peroxidase activity independent of daunomycin. A reporter probe consisting of biotinylated antigen and daunomycin aptamer coupled to streptavidin gold nanoparticles was successfully used to generate a colorimetric readout. In conclusion, the daunomycin aptamer can function as a robust alternative DNAzyme for the development of colorimetric assays.

  3. Evaluation of an in-house dot enzyme-linked immunosorbent assay to detect antibodies against feline panleukopenia virus.

    Science.gov (United States)

    Mende, Katherina; Stuetzer, Bianca; Truyen, Uwe; Hartmann, Katrin

    2014-10-01

    Measuring antibody titres to determine a cat's immunity to core diseases instead of just administering annual vaccinations has not been established in Germany so far. An in-house test kit for the detection of antibodies against feline panleukopenia virus (FPV), feline herpesvirus-1 and feline calicivirus-- the ImmunoComb Feline VacciCheck--is now available in several European countries. The aim of this study was to assess the quality of the ImmunoComb Feline VacciCheck to determine antibodies by comparing it to a gold standard. The test is aimed for use in practice to assist decision-making when performing an individual health assessment to see whether a cat is potentially unprotected against FPV and requires FPV vaccination. Sera from 347 cats were included in the study. For antibody detection, haemagglutination inhibition (HI) was performed as gold standard. Sensitivity, specificity and positive and negative predictive values of the ImmunoComb Feline VacciCheck were determined for three different HI titre cut-off points (1:20, 1:40, 1:80). In comparison to the HI, the ImmunoComb Feline VacciCheck showed a sensitivity of 79%, 83% and 87%, and a specificity of 89%, 86% and 81%, respectively. Specificity of the ImmunoComb Feline VacciCheck, which was considered the most important parameter, was acceptable in comparison to HI. Especially when considering an antibody titre of 1:20 sufficient for protection (eg, in an adult animal), the ImmunoComb Feline VacciCheck can be recommended for use in veterinary practice.

  4. Mycoplasma agassizii strain variation and distinct host antibody responses explain differences between enzyme-linked immunosorbent assays and Western blot assays.

    Science.gov (United States)

    Wendland, Lori D; Klein, Paul A; Jacobson, Elliott R; Brown, Mary B

    2010-11-01

    The precarious status of desert (Gopherus agassizii) and gopher (G. polyphemus) tortoises has resulted in conservation efforts that now include health assessment as an important component of management decision-making. Mycoplasmal upper respiratory tract disease (URTD) is one of very few diseases in chelonians for which comprehensive and rigorously validated diagnostic tests exist. In this study, serum samples obtained from eight Gopherus tortoises documented at necropsy to (i) be enzyme-linked immunosorbent assay (ELISA) seropositive using the PS6 antigen, (ii) be infected with Mycoplasma agassizii as indicated by direct isolation of the pathogen from the respiratory surfaces, and (iii) have histological lesions of mycoplasmal URTD were used to evaluate four distinct clinical isolates of M. agassizii as antigens for ELISA and Western blot analyses. Each animal sample reacted in the Western blot with its homologous M. agassizii strain, but recognition of heterologous M. agassizii strains was variable. Further, individual animals varied significantly with respect to the specific proteins recognized by the humoral immune response. An additional 114 Gopherus serum samples were evaluated using ELISA antigens prepared from the four distinct M. agassizii strains; A₄₀₅ values were significantly correlated (r² goodness of fit range, 0.708 to 0.771; P Western blot binding patterns. Thus, reliance on a single M. agassizii strain as an antigen in Western blot assays may provide false-negative results. This could have adverse consequences for the well-being of these environmentally sensitive hosts if false-negative animals were relocated to sites consisting of true-negative populations.

  5. 结核抗体检测在住院患者结核病诊断中的临床意义%Clinical value of tuberculosis antibody assays in diagnosis of inpatients with tuberculosis

    Institute of Scientific and Technical Information of China (English)

    马秀清; 陈良安; 李春笋; 梁媛; 于玲

    2011-01-01

    目的 探讨结核抗体检测在住院患者结核病诊断中的临床价值.方法 对医院1911例住院患者,应用3种方法同时检测血清结核抗体的结果进行回顾性分析.结果 3种方法联合检测结核抗体的敏感性为79.8%,特异性为81.9%,结果优于单一检测,均P=0.000;与传统方法相比,3种方法联合检测结核抗体的阳性率为77.6%,优于抗酸染色法(33.6%,P=0.000),略高于结核菌素试验法(66.4%),差异无统计学意义.结论 3种方法联合检测结核抗体,敏感性高,操作简单、快捷,成本低,对住院患者结核病辅助诊断有重要的临床应用价值.%OBJECTIVE To investigate the clinical value of the tuberculosis antibody assays in the diagnosis of InPatients with tuberculosis.METHODS The results of serum Mycobacterium tuberculosis antibody (TB-Ab) tests of 1911 inpatients were retrospectively analyzed.RESULTS The sensitivity and specificity of combined measurement of immunochromatographic method, dot-immunogold filtration assay (DTBA) and immunoblotting method were 79.8% and 81.9%, respectively.They were obviously higher than that of single detection.TB-Ab assay, P=0.000.Compared with traditional methods, the positive rate of the combined measurement of three methods (77.6%) was significantly higher than sputum acid-fast bacillus (AFB) smear method (33.6%, p=0.000), and higher than PPD test (66.4 %), while there was no statistical difference, P= 0.068.CONCLUSION With high sensitivity, simple operation and low cost, the combined measurement of 3 TB-Ab assays helps to make an accurate clinical diagnosis of tuberculosis.

  6. Development of Enzyme Linked Immunosorbent Assay for Quantita-tive Determination of Agonistic DR5 Monoclonal Antibody%抗 DR5单克隆抗体 ELISA 检测新方法的建立

    Institute of Scientific and Technical Information of China (English)

    郭聪; 陈知航; 许先兴; 刘运龙; 车津晶; 董俊兴; 程远国

    2013-01-01

    Objective: To develop a specific, sensitive and rapid ELISA method for the quantification of agonistic death receptor 5(DR5) monoclonal antibody. Methods: An quantitative sandwich enzyme immunoassay was devel⁃oped in using goat anti-human IgG for capturing as well as detecting. Following that, color was developed by the substrate solution and the reaction was stopped by stop solution. Finally the plate was read at a wavelength of 450 nm using a microplate reader. Results: An ELISA assay was developed with a wide dynamic range of con⁃centrations from 12.5 to 800 ng/mL. The lowest quantification of this assay was 12.5 ng/mL, both accuracy of the intra- and inter-assay were less than 15%. Conclusion: The assay is highly sensitive, accurate, specific, and re⁃producibility over a wide dynamic range of concentrations, which was proven to be a feasible quantitative method for agonistic DR5 monoclonal antibody analysis.%  目的:建立一种灵敏、特异、快速的 ELISA 方法,用猕猴血清中抗死亡受体5(DR5)单克隆抗体的检测.方法:采用双抗夹心 ELISA 法,用猴血清吸附的羊抗人 IgG 包被96孔酶标板,加入待测样品,用 HRP 标记的猴血清吸附的羊抗人 IgG 进行检测,加底物显色,读取 D450nm值.结果:建立了检测抗 DR5单克隆抗体的 ELISA 方法并进行了确证,方法的线性范围为12.5~800 ng/mL,定量下限为12.5 ng/mL,板内和板间精密度均小15%,准确度为±15%,冻融稳定性和稀释稳定性良好.结论:方法学确证结果表明,本研究建立的抗 DR5单克隆抗体检测方法符合新生物制品临床前药代动力学研究指导则要求,可用抗 DR5单克隆抗体的检测.

  7. Monoclonal antibody production and indirect competitive enzyme-linked immunosorbent assay development of 3-methyl-quinoxaline-2-carboxylic acid based on novel haptens.

    Science.gov (United States)

    Li, Guopeng; Zhao, Liang; Zhou, Feng; Li, Jiaying; Xing, Yuan; Wang, Tiangang; Zhou, Xilong; Ji, Baoping; Ren, Wanpeng

    2016-10-15

    Two novel immunizing haptens of 3-methyl-quinoxaline-2-carboxylic acid (MQCA) were synthesized and conjugated with cationized bovine serum albumin. Female BALB/c mice were immunized with above conjugates, splenocytes were fused with Sp2/0 cells to produce monoclonal antibody. Compared with previous studies, antibodies raised in this work showed higher sensitivity. Meantime, a novel heterologous coating hapten was also prepared. The indirect competitive enzyme-linked immunosorbent assay (icELISA) based on the optimum condition showed an IC50 of 3.1μg/kg (ppb), and the linear range of 0.46-10.5ppb for MQCA. The limit of detect (LOD) of MQCA in swine muscle, swine liver and chicken was 0.32, 0.54, and 0.28ppb, respectively. The LOD of this assay can satisfy the minimum required performance levels (4ppb) for MQCA. These results indicated that the proposed ELISA, with high sensitivity and specificity, as well as good reproducibility and accuracy, is suitable for determination of MQCA residues in food samples.

  8. Antibody Response to Plague Vaccination in Humans as Assayed by Staphylococcal Radioimmune Precipitation (St-RIP) Test

    Science.gov (United States)

    1980-08-22

    Medical Microbiology and Immunology 163, 25-35. Cavanaugh, D. C., Elisberg, B. L., Llewellyn, C. H., Marshall, J. D., Jr., Rust, J. H.,I: Williams J. E...Schaeg, W. (1977). A radioimmunoassay for tetanus antibodies using protein A-containing Staphylococcus aureus. Medical Microbiology and Immunology 163...Putenherpesvirus. Medical Microbiology and Immunology 163, 14l-156. Kessler, S. W. (1975) Rapid isolation of antigens from tells with a staphylococa! protein

  9. Peptide-Based Protein Capture Agents with High Affinity, Selectivity, and Stability as Antibody Replacements in Biodetection Assays

    Science.gov (United States)

    2014-08-01

    agent, peptide-based sensors, biological detection, antibody replacements 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT...recombinant protein to that of Ricin, the F1 surface protein of Yersinia pestis required for effective internalization into cells [ref], the neurotoxin...ligand in addition to PA, including MS2 coat protein (MS2CP), Rivax, the F1 surface protein of Yersinia pestis, HS33A of Clostridium botulinum, and the

  10. Fluorescent ligand binding and internalization assays to identify and profile anti Formyl Receptor 1 (FPR1) antibodies

    OpenAIRE

    Peter Cariuk

    2015-01-01

    GPCR's are involved in a variety of diseases spanning a range of therapeutic areas and have historically been the domain of small molecule drugs. Recent technological advances have opened the possibility to develop therapeutic human monoclonal antibodies in multiple disease areas, conferring additional benefits such as specificity and longer duration of action. FPR1 is a Class A GPCR and is activated by N-formylated peptides (FPR), which can be released by bacterial colonization and lung tiss...

  11. In vitro killing assays of antisera antibody sheep post-infected with Fasciola gigantica with the presence of macrophages cells against homologous and heterologous liver flukes

    Directory of Open Access Journals (Sweden)

    S.E Estuningsih

    1999-10-01

    Full Text Available The previous artificial infection known that the Indonesian Thin Tail (ITT sheep was resistance against the liver fluke of Fasciola gigantica, the resistances occurred in the early infection. In order to observe the immune resistance, some in vitro studies were undertaken in the laboratory, to assay the ability of the antisera antibody of ITT sheep post-infected with F. gigantica, with the presence of macrophages cells in killing the homologous and heterologous liver flukes. The viability of liver flukes were observed within 24-72 hours of incubation period by observing their motility (motile flukes were designated live and non-motile once were death. The results showed that after 72 hours incubation, the motilities of the Newly Excysted Juvenile (NEJ of F. gigantica incubated with the presence of post-infected sera and macrophages cells solution were significantly lower (P0.05. It seems that the occurrence of homologous antibody to the antigens is very important in the development of killing mechanism. The absence of homologous antibody did not reduce the number of flukes or the ability of macrophages cells in killing F. hepatica was not apparent.

  12. Anti-VP1 and anti-VP2 antibodies detected by immunofluorescence assays in patients with acute human parvovirus B19 infection

    Directory of Open Access Journals (Sweden)

    Pereira Renata FA

    2001-01-01

    Full Text Available Acute human parvovirus B19 infection is followed by an antibody response to the structural proteins of the viral capsid (VP1 and VP2. We used 80 sera collected from 58 erythema infectiosum and 6 transient aplastic crisis patients to test IgM and IgG antibodies against these two proteins in an immunofluorescence assay (IFA using Sf9 cells infected with recombinant baculovirus expressing either VP1 or VP2 antigen. Although less sensitive than IgM capture enzyme immunoassay using native antigen (MACEIA, we could detect anti-VP1 or anti-VP2 IgM antibodies by IFA in 49 patients with acute infection (76.6%. Detection of IgG anti-VP1 and anti-VP2 by IFA, however, was as sensitive as IgG detection by indirect enzyme immunoassay. By applying IgG avidity IFA to sera of the 15 IgM IFA negative patients we were able to confirm acute infection in further 12 cases by IFA. Overall, acute infection was confirmed by IFA in 61 (95.3% of the 64 patients.

  13. Nucleoprotein-based indirect enzyme-linked immunosorbent assay(indirect ELISA) for detecting antibodies specific to Ebola virus and Marbug virus

    Institute of Scientific and Technical Information of China (English)

    Yi; Huang; Youjie; Zhu; Mengshi; Yang; Zhenqing; Zhang; Donglin; Song; Zhiming; Yuan

    2014-01-01

    Full-length nucleoproteins from Ebola and Marburg viruses were expressed as His-tagged recombinant proteins in Escherichia coli and nucleoprotein-based enzyme-linked immunosorbent assays(ELISAs) were established for the detection of antibodies specific to Ebola and Marburg viruses. The ELISAs were evaluated by testing antisera collected from rabbit immunized with Ebola and Marburg virus nucleoproteins. Although little cross-reactivity of antibodies was observed in antiEbola virus nucleoprotein rabbit antisera, the highest reactions to immunoglobulin G(Ig G) were uniformly detected against the nucleoprotein antigens of homologous viruses. We further evaluated the ELISA’s ability to detect antibodies to Ebola and Marburg viruses using human sera samples collected from individuals passing through the Guangdong port of entry. With a threshold set at the mean plus three standard deviations of average optical densities of sera tested, the ELISA systems using these two recombinant nucleoproteins have good sensitivity and specificity. These results demonstrate the usefulness of ELISA for diagnostics as well as ecological and serosurvey studies of Ebola and Marburg virus infection.

  14. Development of polyclonal antibody-based indirect enzyme-linked immunosorbent assay for the detection of Alicyclobacillus strains in apple juice.

    Science.gov (United States)

    Wang, Zhouli; Yue, Tianli; Yuan, Yahong; Cai, Rui; Guo, Caixia; Wang, Xin; Niu, Chen

    2012-11-01

    A sort of specific polyclonal anti-Alicyclobacillus antibody was generated by immunizing New Zealand white rabbits, and a sensitive indirect enzyme-linked immunosorbent assay (ELISA) was developed for Alicyclobacillus detection in apple juice. A set of experimental parameters such as concentration of antigen, dilutions of the antibody and goat anti-rabbit IgG-horseradish peroxidase conjugate, selection of the blocking reagent, incubation time, and temperature was optimized. The cross-reactivity of the antibody was evaluated by ELISA and the result was consistent with Western blot analysis. The detection limit of the ELISA was about 10(5) colony forming units (CFU)/mL in apple juice samples. Samples were detected by ELISA and conventional culture method, and the ELISA results gave a good agreement with the results obtained by plating on Alicyclobacillus acidoterrestris medium agar. ELISA takes a total detection time of 6 to 7 h, which is less than the time of conventional techniques requiring more than 24 to 48 h. These results indicated that the established ELISA was a potential useful analytical method for detection of Alicyclobacillus in apple juice.

  15. Development and field application of a competitive enzyme-linked immunosorbent assay for detection of Newcastle disease virus antibodies in chickens and ducks.

    Science.gov (United States)

    Phan, L V; Park, M-J; Kye, S-J; Kim, J-Y; Lee, H-S; Choi, K-S

    2013-08-01

    A competitive enzyme-linked immunosorbent assay (C-ELISA) using a baculovirus-expressed recombinant nucleocapsid protein antigen (rNDV-N) and an rNDV-N-specific monoclonal antibody (5B3) was developed for the detection of Newcastle disease virus (NDV) antibodies, and its diagnostic performance was evaluated. The specificity and sensitivity of the C-ELISA was found to be 98.4 and 98.9%, respectively, for chickens, and 98.2 and 97.9% for ducks. However, the C-ELISA showed weak cross-reaction with hyperimmune antisera to some other avian paramyxovirus serotypes. In all experimentally vaccinated chickens, seroconversion rates at 7 d postinoculation were 100 and 40% when measured by C-ELISA and hemagglutination inhibition (HI), respectively. In field trials, the C-ELISA showed positive results in 98.9% of HI-positive sera and 40.8% of HI-negative sera from NDV-vaccinated chickens (n = 705). In domestic ducks (n = 158) from NDV-positive duck farms (n = 8), the positive rates according to C-ELISA were significantly higher than those according to the HI test. At the same time, 98.1% of ducks (n = 209) from NDV-negative duck farms (n = 11) were also negative by C-ELISA. Our results indicate that C-ELISA could be a useful alternative to HI testing for detecting NDV antibodies in different avian species such as chickens and ducks.

  16. Evaluation of an indirect enzyme-linked immunosorbent assay for routine screening of Theiler's murine encephalomyelitis virus antibodies in mice colonies.

    Science.gov (United States)

    Laborde, Juan M; Carbone, Cecilia; Corva, Santiago G; Galosi, Cecilia M

    2008-11-01

    The current study demonstrates the ability of an indirect enzyme-linked immunosorbent assay (iELISA) to detect antibodies against Theiler's murine encephalomyelitis virus in mice colonies. The antigen was produced from infected baby hamster kidney (BHK)-21 cells and treated with 1% Nonidet P40 in saline buffer. Control antigen was prepared following the same procedure using uninfected BHK-21 cells. The optimal antigen and serum dilutions were established. The reaction was revealed using an anti-mouse-horseradish peroxidase conjugate and 2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid). Optimized iELISA was validated by detection of antibodies in known positive and negative serum samples before testing the samples of unknown status. Performance of the iELISA was compared with the indirect fluorescent antibody test, and the cutoff value was determined by receiver operating curve. Indirect ELISA showed 100% sensitivity, 99.38% specificity, and 97.78% predictive positive value. The antigen used is easy to produce, and no special equipment is required. The iELISA developed is simple and provides a rapid and less costly tool for diagnosis and research.

  17. Nucleoprotein-based indirect enzyme-linked immunosorbent assay (indirect ELISA) for detecting antibodies specific to Ebola virus and Marbug virus.

    Science.gov (United States)

    Huang, Yi; Zhu, Youjie; Yang, Mengshi; Zhang, Zhenqing; Song, Donglin; Yuan, Zhiming

    2014-12-01

    Full-length nucleoproteins from Ebola and Marburg viruses were expressed as His-tagged recombinant proteins in Escherichia coli and nucleoprotein-based enzyme-linked immunosorbent assays (ELISAs) were established for the detection of antibodies specific to Ebola and Marburg viruses. The ELISAs were evaluated by testing antisera collected from rabbit immunized with Ebola and Marburg virus nucleoproteins. Although little cross-reactivity of antibodies was observed in anti-Ebola virus nucleoprotein rabbit antisera, the highest reactions to immunoglobulin G (IgG) were uniformly detected against the nucleoprotein antigens of homologous viruses. We further evaluated the ELISA's ability to detect antibodies to Ebola and Marburg viruses using human sera samples collected from individuals passing through the Guangdong port of entry. With a threshold set at the mean plus three standard deviations of average optical densities of sera tested, the ELISA systems using these two recombinant nucleoproteins have good sensitivity and specificity. These results demonstrate the usefulness of ELISA for diagnostics as well as ecological and serosurvey studies of Ebola and Marburg virus infection.

  18. An Automated High-Throughput Metabolic Stability Assay Using an Integrated High-Resolution Accurate Mass Method and Automated Data Analysis Software

    Science.gov (United States)

    Shah, Pranav; Kerns, Edward; Nguyen, Dac-Trung; Obach, R. Scott; Wang, Amy Q.; Zakharov, Alexey; McKew, John; Simeonov, Anton; Hop, Cornelis E. C. A.

    2016-01-01

    Advancement of in silico tools would be enabled by the availability of data for metabolic reaction rates and intrinsic clearance (CLint) of a diverse compound structure data set by specific metabolic enzymes. Our goal is to measure CLint for a large set of compounds with each major human cytochrome P450 (P450) isozyme. To achieve our goal, it is of utmost importance to develop an automated, robust, sensitive, high-throughput metabolic stability assay that can efficiently handle a large volume of compound sets. The substrate depletion method [in vitro half-life (t1/2) method] was chosen to determine CLint. The assay (384-well format) consisted of three parts: 1) a robotic system for incubation and sample cleanup; 2) two different integrated, ultraperformance liquid chromatography/mass spectrometry (UPLC/MS) platforms to determine the percent remaining of parent compound, and 3) an automated data analysis system. The CYP3A4 assay was evaluated using two long t1/2 compounds, carbamazepine and antipyrine (t1/2 > 30 minutes); one moderate t1/2 compound, ketoconazole (10 < t1/2 < 30 minutes); and two short t1/2 compounds, loperamide and buspirone (t½ < 10 minutes). Interday and intraday precision and accuracy of the assay were within acceptable range (∼12%) for the linear range observed. Using this assay, CYP3A4 CLint and t1/2 values for more than 3000 compounds were measured. This high-throughput, automated, and robust assay allows for rapid metabolic stability screening of large compound sets and enables advanced computational modeling for individual human P450 isozymes. PMID:27417180

  19. Development and evaluation of a new lateral flow assay for simultaneous detection of antibodies against African Horse Sickness and Equine Infectious Anemia viruses.

    Science.gov (United States)

    Costa, Sofia; Sastre, Patricia; Pérez, Teresa; Tapia, Istar; Barrandeguy, María; Sánchez-Vizcaíno, José M; Sánchez-Matamoros, Almudena; Wigdorovitz, Andrés; Sanz, Antonio; Rueda, Paloma

    2016-11-01

    African horse sickness (AHS) and equine infectious anemia (EIA) are both notifiable equid specific diseases that may present similar clinical signs. Considering the increased global movement of horses and equine products over the past decades, together with the socio-economic impact of previous AHS and EIA outbreaks, there is a clear demand for an early discrimination and a strict control of their transmission between enzootic and AHS/EIA-free regions. Currently, the individual control and prevention of AHS or EIA relies on a series of measures, including the restriction of animal movements, vector control, and the use of several laboratory techniques for viral identification, amongst others. Despite being widely employed in surveillance programmes and in the control of animal movements, the available serological assays can only detect AHS- or EIA-specific antibodies individually. In this work, a duplex lateral flow assay (LFA) for simultaneous detection and differentiation of specific antibodies against AHS virus (AHSV) and EIA virus (EIAV) was developed and evaluated with experimental and field serum samples. The duplex LFA was based on the AHSV-VP7 outer core protein and the EIAV-P26 major core protein. The results indicated that the duplex LFA presented a good analytical performance, detecting simultaneously and specifically antibodies against AHSV and EIAV. The initial diagnostic evaluation revealed a good agreement with results from the AHS and EIA tests prescribed by the OIE, and it highlighted the usefulness of the new AHSV/EIAV duplex LFA for an on-field and point-of-care first diagnosis. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Analysis of epitopes on dengue virus envelope protein recognized by monoclonal antibodies and polyclonal human sera by a high throughput assay.

    Directory of Open Access Journals (Sweden)

    Hong-En Lin

    2012-01-01

    Full Text Available BACKGROUND: The envelope (E protein of dengue virus (DENV is the major target of neutralizing antibodies and vaccine development. While previous studies on domain III or domain I/II alone have reported several epitopes of monoclonal antibodies (mAbs against DENV E protein, the possibility of interdomain epitopes and the relationship between epitopes and neutralizing potency remain largely unexplored. METHODOLOGY/PRINCIPAL FINDINGS: We developed a dot blot assay by using 67 alanine mutants of predicted surface-exposed E residues as a systematic approach to identify epitopes recognized by mAbs and polyclonal sera, and confirmed our findings using a capture-ELISA assay. Of the 12 mouse mAbs tested, three recognized a novel epitope involving residues (Q211, D215, P217 at the central interface of domain II, and three recognized residues at both domain III and the lateral ridge of domain II, suggesting a more frequent presence of interdomain epitopes than previously appreciated. Compared with mAbs generated by traditional protocols, the potent neutralizing mAbs generated by a new protocol recognized multiple residues in A strand or residues in C strand/CC' loop of DENV2 and DENV1, and multiple residues in BC loop and residues in DE loop, EF loop/F strand or G strand of DENV1. The predominant epitopes of anti-E antibodies in polyclonal sera were found to include both fusion loop and non-fusion residues in the same or adjacent monomer. CONCLUSIONS/SIGNIFICANCE: Our analyses have implications for epitope-specific diagnostics and epitope-based dengue vaccines. This high throughput method has tremendous application for mapping both intra and interdomain epitopes recognized by human mAbs and polyclonal sera, which would further our understanding of humoral immune responses to DENV at the epitope level.

  1. The Cobas AmpliPrep/Cobas TaqMan HCV Test, Version 2.0, Real-Time PCR Assay Accurately Quantifies Hepatitis C Virus Genotype 4 RNA

    OpenAIRE

    Chevaliez, Stéphane; Bouvier-Alias, Magali; Rodriguez, Christophe; Soulier, Alexandre; Poveda, Jean-Dominique; Pawlotsky, Jean-Michel

    2013-01-01

    Accurate hepatitis C virus (HCV) RNA quantification is mandatory for the management of chronic hepatitis C therapy. The first-generation Cobas AmpliPrep/Cobas TaqMan HCV test (CAP/CTM HCV) underestimated HCV RNA levels by >1-log10 international units/ml in a number of patients infected with HCV genotype 4 and occasionally failed to detect it. The aim of this study was to evaluate the ability of the Cobas AmpliPrep/Cobas TaqMan HCV test, version 2.0 (CAP/CTM HCV v2.0), to accurately quantify H...

  2. Anti-apical-membrane-antigen-1 antibody is more effective than anti-42-kilodalton-merozoite-surface-protein-1 antibody in inhibiting plasmodium falciparum growth, as determined by the in vitro growth inhibition assay.

    Science.gov (United States)

    Miura, Kazutoyo; Zhou, Hong; Diouf, Ababacar; Moretz, Samuel E; Fay, Michael P; Miller, Louis H; Martin, Laura B; Pierce, Mark A; Ellis, Ruth D; Mullen, Gregory E D; Long, Carole A

    2009-07-01

    Apical membrane antigen 1 (AMA1) and the 42-kDa merozoite surface protein 1 (MSP1(42)) are leading malaria vaccine candidates. Several preclinical and clinical trials have been conducted, and an in vitro parasite growth inhibition assay has been used to evaluate the biological activities of the resulting antibodies. In a U.S. phase 1 trial with AMA1-C1/Alhydrogel plus CPG 7909, the vaccination elicited anti-AMA1 immunoglobulin G (IgG) which showed up to 96% inhibition. However, antibodies induced by MSP1(42)-C1/Alhydrogel plus CPG 7909 vaccine showed less than 32% inhibition in vitro. To determine whether anti-MSP1(42) IgG had less growth-inhibitory activity than anti-AMA1 IgG in vitro, the amounts of IgG that produced 50% inhibition of parasite growth (Ab(50)) were compared for rabbit and human antibodies. The Ab(50)s of rabbit and human anti-MSP1(42) IgGs were significantly higher (0.21 and 0.62 mg/ml, respectively) than those of anti-AMA1 IgGs (0.07 and 0.10 mg/ml, respectively) against 3D7 parasites. Ab(50) data against FVO parasites also demonstrated significant differences. We further investigated the Ab(50)s of mouse and monkey anti-AMA1 IgGs and showed that there were significant differences between the species (mouse, 0.28 mg/ml, and monkey, 0.14 mg/ml, against 3D7 parasites). Although it is unknown whether growth-inhibitory activity in vitro reflects protective immunity in vivo, this study showed that the Ab(50) varies with both antigen and species. Our data provide a benchmark for antibody levels for future AMA1- or MSP1(42)-based vaccine development efforts in preclinical and clinical trials.

  3. Detection of Salmonella enterica serovar Enteritidis (SE) Antibodies in Serum Using A Polystyrene Bead/SE Flagella Agglutination Assay

    Science.gov (United States)

    Serologic screening of flocks can be an important method to detect Salmonella enteritidis (SE) infections but can be labor intensive or lack specificity. Our goal was to develop a rapid agglutination assay using SE flagella adsorbed to polystyrene beads as a simple, relatively specific test to dete...

  4. Evaluation of a monoclonal antibody-based enzyme-linked immunosorbent assay for detection of Campylobacter fetus in bovine preputial washing and vaginal mucus samples.

    Science.gov (United States)

    Brooks, B W; Devenish, J; Lutze-Wallace, C L; Milnes, D; Robertson, R H; Berlie-Surujballi, G

    2004-10-05

    A monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) was described and evaluated for use as a presumptive screening test for detection of Campylobacter fetus in bovine preputial washing and vaginal mucus samples. A total of 725 diagnostic samples collected in the field and submitted in Clark's transport enrichment medium (TEM) were analyzed. Cultural isolation of C. fetus was used as the standard for comparison. After incubation of the TEM vials for 4-5 days, fluid was removed for culture and ELISA testing. A sandwich ELISA format was used and the target antigen was C. fetus lipopolysaccharides (LPS). A rabbit anti-C. fetus polyclonal antiserum was used as the capture antibody. Murine monoclonal antibodies (MAbs) to C. fetus serotype A and B LPS core and O-polysaccharides and a goat anti-mouse horseradish peroxidase conjugate were used as detection antibodies. ELISA and culture results for the diagnostic samples were in complete agreement. Seven hundred and eight samples were negative by both tests. All 17 culture positive samples were positive by ELISA with a MAb to LPS core. The ELISA with MAbs to LPS O-polysaccharides detected all culture positive samples with the homologous C. fetus serotype. Sixty-six preputial wash samples from three known C. fetus culture positive bulls were also analyzed. Forty-nine of these samples were positive by both ELISA and culture, 16 were positive by ELISA only, and one was negative by both ELISA and culture. The results indicate that this ELISA is useful as a screening test for the detection of C. fetus in diagnostic samples.

  5. Antibody levels correlate with detection of Trypanosoma cruzi DNA by sensitive PCR assays in seropositive blood donors and possible resolution of infection over time

    Science.gov (United States)

    Sabino, E.C.; Lee, T.H.; Montalvo, L.; Nguyen, M.L.; Leiby, D.A.; Carrick, D.M.; Otani, M.M.; Vinelli, E.; Wright, D.; Stramer, S.L.; Busch, M.

    2013-01-01

    Background The clinical significance of anti-T. cruzi low-level reactive samples is incompletely understood. PCR-positive rates and antibody levels among seropositive blood donors in three countries are described. Methods Follow-up whole blood and plasma samples were collected from T. cruzi-seropositive donors from 2008-2010 in the US (n=195) and Honduras (n=58). Also 143 samples from Brazil in 1996-2002, originally positive by three serological assays, were available and paired with contemporary follow-up samples from these donors. All samples were retested with the FDA-approved Ortho ELISA. PCR assays were performed on coded sample panels by two laboratories (BSRI and ARC) that amplified kinetoplast minicircle DNA sequences of T. cruzi. Results PCR testing at BSRI yielded slightly higher overall sensitivity and specificity (33% and 98%) compared with the ARC lab (28% and 94%). Among seropositive donors, PCR-positive rates varied by country (p<0.0001) for the BSRI laboratory: Brazil (57%), Honduras (32%) and the US (14%). ELISA signal/cutoff (S/CO) ratios were significantly higher for PCR-positive compared to PCR-negative donors (p<0.05 for all comparisons). Additionally, PCR-negative Brazilian donors exhibited greater frequencies of antibody decline over time versus PCR-positive donors (p=0.003). Conclusion For all three countries, persistent DNA positivity correlated with higher ELISA S/CO values, suggesting that high-level seroreactivity reflects chronic parasitemia. The higher rate of PCR positivity for Brazilian donors was likely attributable to required reactivity on three assays available a decade ago. Significant S/CO declines in 10% of the PCR-negative Brazilian donors may indicate seroreversion following parasite clearance in the absence of treatment. PMID:23002996

  6. Antithyroglobulin antibody

    Science.gov (United States)

    Thyroglobulin antibody; Thyroiditis - thyroglobulin antibody; Hypothyroidism - thyroglobulin antibody; Thyroiditis - thyroglobulin antibody; Graves disease - thyroglobulin antibody; Underactive thyroid - thyroglobulin antibody

  7. An ultra-sensitive monoclonal antibody-based enzyme-linked immunosobent assay for dibutyl phthalate in human urinary

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Lifang [Institute of Pharmacology, Toxicology and Biochemical Pharmaceutics, College of Pharmaceutical Science, Zhejiang University, Hangzhou 310058 (China); Lei, Yajing [Hangzhou EPIE Bio-detection Technology Limited, Hangzhou 310051 (China); Zhang, Dai; Ahmed, Shabbir [Institute of Pharmacology, Toxicology and Biochemical Pharmaceutics, College of Pharmaceutical Science, Zhejiang University, Hangzhou 310058 (China); Chen, Shuqing, E-mail: chenshuqing@zju.edu.cn [Institute of Pharmacology, Toxicology and Biochemical Pharmaceutics, College of Pharmaceutical Science, Zhejiang University, Hangzhou 310058 (China)

    2016-01-15

    Dibutyl phthalate (DBP) has been extensively used as a plasticizer in many daily products, which is highly toxic to human, notably affecting the reproductive and developmental function. As the previous method is expensive, time-consuming, low sensitivity and just focused on the environment. Present study was aimed to establish an ultra-sensitive and simple method based on good quality monoclonal antibody, applying to evaluate excretion level of DBP in urine samples of Chinese population directly. A monoclonal antibody was generated and characterized after fusion of myeloma cells with spleen cells isolated from BALB/c mouse. The mouse was previously immunized using a specially designed amino derivative of DBP conjugated with bovine serum albumin (BSA) as immunogen. Cross-reactivity values of the monoclonal antibody against DBP, di-isobutyl phthalate (DIBP) were observed 100% and 1.25%, while for dimethyl phthalate (DMP), butyl benzyl phthalate (BBP) and didecyl phthalate (DDP) the values were < 0.06%. The standard curve was constructed at 0–50 ng mL{sup −1} and good linearity (R{sup 2} = 0.994) was achieved. The observed IC{sub 50} (7.34 ng mL{sup −1}) and LOD (0.06 ng mL{sup −1}) values was improved 1000-fold to polyclonal antibody and 5-fold to other monoclonal antibodies. A total 1246 urine samples were analyzed and the detection frequency of DBP was observed 72.87% by ic-ELISA. The 95th percentile and mean concentration of DBP were 12.07 and 3.00 ng mL{sup −1}. Acceptable recovery rates of DBP were 97.8–114.3% and coefficients variation 5.93–11.09%. The concentrations of DBP in females were found significantly higher (p < 0.05) than males. Similarly, the DBP in middle aged and low educated individuals was found higher (p < 0.001) than the others. Considering the adverse health effects, DBP internal exposure in the Chinese population should be reduced. The ic-ELISA method has been proved as a cost effective, specific, and highly sensitive screening

  8. Production of monoclonal antibodies against GPCR using cell-free synthesized GPCR antigen and biotinylated liposome-based interaction assay

    OpenAIRE

    Takeda, Hiroyuki; Ogasawara, Tomio; Ozawa, Tatsuhiko; Muraguchi, Atsushi; Jih, Pei-Ju; Morishita, Ryo; Uchigashima, Motokazu; Watanabe, Masahiko; Fujimoto, Toyoshi; Iwasaki, Takahiro; Endo, Yaeta; Sawasaki, Tatsuya

    2015-01-01

    G-protein-coupled receptors (GPCRs) are one of the most important drug targets, and anti-GPCR monoclonal antibody (mAb) is an essential tool for functional analysis of GPCRs. However, it is very difficult to develop GPCR-specific mAbs due to difficulties in production of recombinant GPCR antigens, and lack of efficient mAb screening method. Here we describe a novel approach for the production of mAbs against GPCR using two original methods, bilayer-dialysis method and biotinylated liposome-ba...

  9. IgA anti-Actin antibodies in children with celiac disease: comparison of immunofluorescence with Elisa assay in predicting severe intestinal damage

    Directory of Open Access Journals (Sweden)

    Mora Stefano

    2010-03-01

    Full Text Available Abstract Background Previous studies have demonstrated that the presence of serum IgA antibodies against actin filaments (AAA in patients with celiac disease (CD is strongly associated with mucosal damage and severe degrees of villous atrophy. The aims of the present study were (1 to verify the effectiveness of IgA-AAA in newly diagnosed CD patients in a clinical setting (2 to compare the immunofluorescence assay with ELISA assay; (3 to compare the correlation of our IgA anti-tissue transglutaminase antibodies (tTG-Ab class with mucosal intestinal lesions. Methods 90 patients underwent endoscopy and multiple biopsies for suspected CD on the basis of symptoms, in presence of positive tTG-Ab tests. Twenty biopsied and 25 not-biopsied subjects with negative tTG-Ab were tested as control groups. IgA-AAA assays were performed by indirect immunofluorescence using rat epithelial intestinal cells, and by ELISA with a commercial kit. tTG-Ab assay was a radio-binding assay. Intestinal specimens were collected by upper endoscopy and the histological study was done according to the Marsh's classification modified by Oberhuber (M/O. Auto-antibodies assays and histological evaluation have been performed blindly by skilled operators. Results CD diagnosis was confirmed in 82 patients (type I M/O in 2 patients, IIIA in 18 patients, IIIB in 29 patients and IIIC in 33 patients. Two patients with type 1 lesion in presence of positive tTG-Ab and abdominal complaints, started a gluten free diet. The rate of IgA-AAA positivity (sensitivity by IFI and ELISA in histologically proven celiac disease patients, were 5.5% and 25% patients in IIIA, 27.5% and 34.4% patients in IIIB, 78.8% and 75% in IIIC patients, respectively. Patients with normal or nearly normal mucosa, regardless of tTG-Ab status, presented negative IgA-AAA IFI assay. On the other hand, 1 patient with normal mucosa but positive tTG-Ab, also presented positive IgA-AAA ELISA. All healthy non biopsied

  10. Detection of Lassa virus antinucleoprotein immunoglobulin G (IgG) and IgM antibodies by a simple recombinant immunoblot assay for field use.

    Science.gov (United States)

    Ter Meulen, J; Koulemou, K; Wittekindt, T; Windisch, K; Strigl, S; Conde, S; Schmitz, H

    1998-11-01

    The nucleoprotein of Lassa virus, strain Josiah, was expressed in Escherichia coli as an N-terminally truncated, histidine-tagged recombinant protein. Following affinity purification the protein was completely denatured and spotted onto nitrocellulose membrane. A total of 1 microgram of protein was applied for detection of Lassa virus antibodies (LVA) in a simple immunoblot assay. Specific anti-Lassa immunoglobulin M (IgM) antibodies could be detected by increasing the amount of protein to 5 microgram. A panel of 913 serum specimens from regions in which Lassa virus was endemic and from regions in which Lassa virus was not endemic was used for evaluating the sensitivity and specificity of the LVA immunoblot in comparison to those of an indirect immunofluorescence (IIF) assay. The sera originated from field studies conducted in the Republic of Guinea (570 serum samples) and Liberia (99 serum samples), from inpatients of the clinical department of the Bernhard-Nocht-Institute, Hamburg, Germany (94 serum samples), and from healthy German blood donors (150 serum samples). In comparison to the IIF assay the LVA immunoblot assay had a specificity of 90.0 to 99.3%, depending on the origin of the specimens. The sensitivity was found to be highest for the Guinean samples (90.7%) and was lower for the Liberian samples (75%). Acute Lassa fever was diagnosed by PCR in 12 of 59 (20.3%) patients with fever of unknown origin (FUO) from the Republic of Guinea. On admission to the hospital, nine Lassa fever patients (75%) were reactive by the IgM immunoblot assay. One of the patients was infected with a new Lassa variant, which showed 10.4% variation on the amino acid level in comparison to the prototype strain of Lassa virus, Josiah. Seven PCR-negative patients were reactive by immunoblotting. The positive and negative predictive values of a single IgM immunoblot result for acute, PCR-confirmed Lassa fever were therefore 53.6 and 93.0%, respectively. Because of its high negative

  11. Evaluation of automated multi-parametric indirect immunofluorescence assays to detect anti-neutrophil cytoplasmic antibodies (ANCA) in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA).

    Science.gov (United States)

    Csernok, Elena; Damoiseaux, Jan; Rasmussen, Niels; Hellmich, Bernhard; van Paassen, Pieter; Vermeersch, Pieter; Blockmans, Daniel; Cohen Tervaert, Jan-Willem; Bossuyt, Xavier

    2016-07-01

    The aim of this multicenter EUVAS study was to evaluate the diagnostic performance of multi-parametric indirect immunofluorescence (IIF) assays to detect anti-neutrophil cytoplasmic antibodies (ANCA) in granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA). The study included 912 samples from diseased controls and 249 diagnostic samples from GPA (n=183) and MPA (n=66) patients. The performance of two automated multi-parametric assays [Aklides (Medipan/Generic Assays) and EuroPattern (Euroimmun)] combining IIF on cellular and purified antigen substrates was compared with two manual IIF analyses and with commercially available ELISAs for MPO- and PR3-ANCA (Euroimmun). The area under the curve (AUC) of the receiver operating characteristics (ROC) curve to discriminate AAV from controls was 0.925, 0.848, 0.855 and 0.904 for, respectively, the two manual analyses, Aklides and EuroPattern, and 0.959, 0.921 and 0.886 for, respectively, antigen-specific ELISA, antigen-coated beads, and microdot, respectively. Variation in pattern assignment between IIF methods was observed. The performance of IIF depends on the substrate used and the definition of IIF patterns. The performance of automated IIF is improved by multi-parameter testing (combined IIF and antigen-specific testing). Given the variability between IIF methods, the diagnostic importance of this technique is questioned. Copyright © 2016. Published by Elsevier B.V.

  12. An evaluation study of enzyme-linked immunosorbent assay (ELISA) using recombinant protein Pap31 for detection of antibody against Bartonella bacilliformis infection among the Peruvian population.

    Science.gov (United States)

    Angkasekwinai, Nasikarn; Atkins, Erin H; Romero, Sofia; Grieco, John; Chao, Chien Chung; Ching, Wei Mei

    2014-04-01

    Reliable laboratory testing is of great importance to detect Bartonella bacilliformis infection. We evaluated the sensitivity and specificity of the enzyme-linked immunosorbent assay (ELISA) using recombinant protein Pap31 (rPap31) for the detection of antibodies against B. bacilliformis as compared with immunofluorescent assay (IFA). Of the 302 sera collected between 1997 and 2000 among an at-risk Peruvian population, 103 and 34 samples tested positive for IFA-immunoglobulin G (IgG) and IFA-IgM, respectively. By using Youden's index, the cutoff values of ELISA-IgG at 0.915 gave a sensitivity of 84.5% and specificity of 94%. The cutoff values of ELISA-IgM at 0.634 gave a sensitivity of 88.2% and specificity of 85.1%. Using latent class analysis, estimates of sensitivity and specificity of almost all the assays were slightly higher than those of a conventional method of calculation. The test is proved beneficial for discriminating between infected and non-infected individuals with the advantage of low-cost and high-throughput capability.

  13. Comparison of Laboratory-Developed and Commercial Monoclonal Antibody-Based Sandwich Enzyme-Linked Immunosorbent Assays for Almond (Prunus dulcis) Detection and Quantification.

    Science.gov (United States)

    Liu, Changqi; Chhabra, Guneet S; Zhao, Jing; Zaffran, Valerie D; Gupta, Sahil; Roux, Kenneth H; Gradziel, Thomas M; Sathe, Shridhar K

    2017-09-04

    A commercially available monoclonal antibody (mAb)-based direct sandwich enzyme-linked immunosorbent assay (ELISA) kit (BioFront Technologies, Tallahassee, Fla., U.S.A.) was compared with an in-house developed mAb 4C10-based ELISA for almond detection. The assays were comparable in sensitivity (limit of detection < 1 ppm full fat almond, limit of quantification < 5 ppm full fat almond), specificity (no cross-reactivity with 156 tested foods at a concentration of 100000 ppm whole sample), and reproducibility (intra- and interassay variability < 15% CV). The target antigens were stable and detectable in whole almond seeds subjected to autoclaving, blanching, frying, microwaving, and dry roasting. The almond recovery ranges for spiked food matrices were 84.3% to 124.6% for 4C10 ELISA and 81.2% to 127.4% for MonoTrace ELISA. The almond recovery ranges for commercial and laboratory prepared foods with declared/known almond amount were 30.9% to 161.2% for 4C10 ELISA and 38.1% to 207.6% for MonoTrace ELISA. Neither assay registered any false-positive or negative results among the tested commercial and laboratory prepared samples. © 2017 Institute of Food Technologists®.

  14. An antibody induction method in mice for the potency assays of diphtheria and tetanus components in combined vaccines.

    Science.gov (United States)

    Maheshwari, S C; Sharma, S B; Kumar, A; Sokhey, J

    1998-09-01

    Eleven batches of Adsorbed Diphtheria-Tetanus (DT) vaccines and thirteen batches of Adsorbed Diphtheria-Pertussis-Tetanus (DTP) vaccines were tested for the potency of diphtheria and tetanus components by an Antibody Induction Method (AIM) developed in mice. The potency results obtained were found comparable and did not show any statistically significant difference with those obtained by WHO recommended lethal challenge tests for diphtheria in guinea pigs and for tetanus in mice. AIM in mice is more economical as both diphtheria and tetanus components of combined vaccine can be tested in the same experiment and the procedure also eliminates the use of guinea pigs required in the lethal challenge/conventional tests. The data obtained while testing tetanus component by the conventional antibody induction (IP) method in guinea pigs suggests that minimum requirements laid down in i.p. is too low which may be fixed as at least 3 out of 9 guinea pig sera and should contain > or = 4 units of tetanus antitoxin per ml.

  15. Direct Replacement of Antibodies with Molecularly Imprinted Polymer Nanoparticles in ELISA-Development of a Novel Assay for Vancomycin

    OpenAIRE

    Chianella, Iva; Guerreiro, Antonio; Moczko, Ewa; Caygill, J. Sarah; Piletska, Elena V.; Perez De Vargas Sansalvador, Isabel M.; Whitcombe, Michael J.; Piletsky, Sergey A.

    2013-01-01

    A simple and straightforward technique for coating microplate wells with molecularly imprinted polymer nanoparticles (nanoMIPs) to develop ELISA type assays is presented here for the first time. NanoMIPs were synthesized by a solid phase approach with immobilized vancomycin (template) and characterized using Biacore 3000, dynamic light scattering and electron microscopy. Immobilization, blocking and washing conditions were optimized in microplate format. The detection of vancomycin was achiev...

  16. Diagnostic accuracy of IgA anti-tissue transglutaminase antibody assays in celiac disease patients with selective IgA deficiency.

    Science.gov (United States)

    Villalta, D; Alessio, M G; Tampoia, M; Tonutti, E; Brusca, I; Bagnasco, M; Pesce, G; Bizzaro, N

    2007-08-01

    Clinical studies have estimated a 10- to 20-fold increased risk for celiac disease (CD) in patients with selective IgA deficiency (SIgAD). For this reason, screening for CD is mandatory in SIgAD patients, but it represents a special challenge since the specific IgA class antibodies against gliadin (AGA), endomysium (EMA), and tissue-transglutaminase (tTG) are not produced in patients with CD. IgG class counterparts of these antibodies may be informative; in particular IgG EMA has been demonstrated to be a valid marker for diagnosing CD in SIgAD cases, but it is not used much in clinical laboratories, because it is cumbersome and involves some technical difficulties. Even if it was widely used in clinical laboratories, the measuring of IgG AGA has shown a less-than-optimum diagnostic accuracy, so that now it tends to be substituted by tests for anti-tTG IgG, for which the few available studies have shown diagnostic performances superior to AGA. Since it is not known whether various available methods for measuring IgG anti-tTG antibodies offer similar diagnostic performances, we have compared the results obtained from nine second-generation commercial methods (D-tek, Phadia, Immco, Orgentec, Radim, Euroimmun, Inova, Aesku, Generic Assays), measuring IgG anti-tTG antibodies in 20 patients with CD and SIgAD and in 113 controls (9 patients with SIgAD without CD, 54 patients with chronic liver disease, and 50 healthy individuals). Diagnostic sensitivity, calculated by means of ROC plot analysis, ranged between 75% and 95%, and specificity ranged from 94% to 100%. In the same population, the diagnostic sensitivity and specificity of AGA IgG were 40% and 87%, respectively. Even though they perform differently, all IgG anti-tTG methods evaluated are reliable serological assays for the diagnosis of CD in SIgAD patients, with diagnostic accuracy superior to the AGA IgG method. The methods that use a mix of tTG and gliadin peptides as the antigenic preparation have a

  17. Rabies neutralizing antibody detection by indirect immunperoxidase serum neutralization assay performed on chicken embryo related cell line

    Directory of Open Access Journals (Sweden)

    Tereza Cristina Cardoso

    2004-08-01

    Full Text Available The aim of this study was to evaluate the indirect immunoperoxidase virus neutralization (IPVN and mouse neutralization test (MNT to detect antibodies against rabies virus from vaccinated dogs and cattle. The IPVN was set up for the ability to measure 0.5 International Units/ml (IU of antibody required by the World Health Organization and the Office International des Epizooties as the minimum response for proof of rabies immunization. IPVN was developed and standardized in chicken embryo related (CER cell line when 141 dog and 110 cattle sera were applied by serial five-fold dilutions (1:5, 1:25, 1:125 as well as the positive and negative reference controls, all added in four adjacent wells, of 96-well microplates. A 50 µl amount of CVS32 strain dilution containing 50-200 TCID50/ml was mixed to each serum dilution, and after 90 min 50 µl of 3 x 10(5 cells/mlcell suspension added to each well. After five days of incubation, the monolayers were fixed and the IPVN test performed. The correlation coefficient between the MNT and IPVN performed in CER cells was r = 0.9949 for dog sera (n = 100 and r = 0.9307 for cattle sera (n = 99, as well as good specificity (94.7%, sensitivity (87.5%, and agreement (96.6% were also obtained. IPVN technique can adequately identify vaccinated and unvaccinated animals, even from low-responding vaccinated animals, with the advantage of low cost and faster then MNT standard test.

  18. Evaluation of modified Ziehl-Neelsen, direct fluorescent-antibody and PCR assay for detection of Cryptosporidium spp. in children faecal specimens.

    Science.gov (United States)

    Aghamolaie, S; Rostami, A; Fallahi, Sh; Tahvildar Biderouni, F; Haghighi, A; Salehi, N

    2016-09-01

    To determine the sensitivity and specificity of routine screening methods for cryptosporidiosis, three methods including conventional modified Ziehl-Neelsen (MZN), direct fluorescent-antibody (DFA) and Nested-PCR assay compared together. To this end, their ability to identify the low concentrations of Cryptosporidium spp. oocysts in children fecal samples was evaluated. The sample population of this study was children under 12 years old who had diarrhea and referred to pediatric hospitals in Tehran, Iran. 2,510 stool specimens from patients with diarrhea were screened for Cryptosporidium oocysts by concentration method and MZN. To determine sensitivity and specificity, Nested-PCR and DFA were performed on 30 positive and 114 negative samples which previously had been proved by MZN. By using the microscopic method, DFA assay and PCR analysis, a total of 30 (1.2 %), 28 (1.1 %) and 32 (1.27 %) positive samples were detected respectively. According to the results, the sensitivity, specificity, and positive and negative predictive values of the Nested-PCR assay were 100 %, compared to 94, 100, 100, and 98 %, respectively, for MZN and 87.5, 100, 100, and 96 %, respectively, for DFA. Results of the present study showed that the Nested-PCR assay was more sensitive than the other two methods and laboratories can use the Nested-PCR method for precise diagnosis of Cryptosporidium spp. However, regarding the costs of Nested-PCR and its unavailability in all laboratories and hospitals, MZN staining on smears has also enough accuracy for Cryptosporidium diagnosis.

  19. Indirect Enzyme-Linked Immunosorbent Assay for Detection of Brucella melitensis-Specific Antibodies in Goat Milk

    OpenAIRE

    Funk, N. D.; Tabatabai, L B; Elzer, P. H.; Hagius, S D; Martin, B. M.; Hoffman, L J

    2005-01-01

    Brucella melitensis is the cause of brucellosis in sheep and goats, which often results in abortion. Few cases of B. melitensis infection in goats have occurred in the United States over the last 25 years. However, vigilance must be maintained, as it is for the bovine milk industry, to ensure that brucellosis is not introduced into the U.S. goat population. The objective of this study was to develop a sensitive and specific indirect enzyme-linked immunosorbent assay (iELISA) for the detection...

  20. Accurate detection and quantification of the fish viral hemorrhagic Septicemia virus (VHSv) with a two-color fluorometric real-time PCR assay.

    Science.gov (United States)

    Pierce, Lindsey R; Willey, James C; Palsule, Vrushalee V; Yeo, Jiyoun; Shepherd, Brian S; Crawford, Erin L; Stepien, Carol A

    2013-01-01

    Viral Hemorrhagic Septicemia virus (VHSv) is one of the world's most serious fish pathogens, infecting >80 marine, freshwater, and estuarine fish species from Eurasia and North America. A novel and especially virulent strain - IVb - appeared in the Great Lakes in 2003, has killed many game fish species in a series of outbreaks in subsequent years, and shut down interstate transport of baitfish. Cell culture is the diagnostic method approved by the USDA-APHIS, which takes a month or longer, lacks sensitivity, and does not quantify the amount of virus. We thus present a novel, easy, rapid, and highly sensitive real-time quantitative reverse transcription PCR (qRT-PCR) assay that incorporates synthetic competitive template internal standards for quality control to circumvent false negative results. Results demonstrate high signal-to-analyte response (slope = 1.00±0.02) and a linear dynamic range that spans seven orders of magnitude (R(2) = 0.99), ranging from 6 to 6,000,000 molecules. Infected fishes are found to harbor levels of virus that range to 1,200,000 VHSv molecules/10(6) actb1 molecules with 1,000 being a rough cut-off for clinical signs of disease. This new assay is rapid, inexpensive, and has significantly greater accuracy than other published qRT-PCR tests and traditional cell culture diagnostics.

  1. Accurate detection and quantification of the fish viral hemorrhagic Septicemia virus (VHSv with a two-color fluorometric real-time PCR assay.

    Directory of Open Access Journals (Sweden)

    Lindsey R Pierce

    Full Text Available Viral Hemorrhagic Septicemia virus (VHSv is one of the world's most serious fish pathogens, infecting >80 marine, freshwater, and estuarine fish species from Eurasia and North America. A novel and especially virulent strain - IVb - appeared in the Great Lakes in 2003, has killed many game fish species in a series of outbreaks in subsequent years, and shut down interstate transport of baitfish. Cell culture is the diagnostic method approved by the USDA-APHIS, which takes a month or longer, lacks sensitivity, and does not quantify the amount of virus. We thus present a novel, easy, rapid, and highly sensitive real-time quantitative reverse transcription PCR (qRT-PCR assay that incorporates synthetic competitive template internal standards for quality control to circumvent false negative results. Results demonstrate high signal-to-analyte response (slope = 1.00±0.02 and a linear dynamic range that spans seven orders of magnitude (R(2 = 0.99, ranging from 6 to 6,000,000 molecules. Infected fishes are found to harbor levels of virus that range to 1,200,000 VHSv molecules/10(6 actb1 molecules with 1,000 being a rough cut-off for clinical signs of disease. This new assay is rapid, inexpensive, and has significantly greater accuracy than other published qRT-PCR tests and traditional cell culture diagnostics.

  2. Improved diagnostic performance of a commercial Anaplasma antibody competitive enzyme-linked immunosorbent assay using recombinant major surface protein 5-glutathione S-transferase fusion protein as antigen.

    Science.gov (United States)

    Chung, Chungwon; Wilson, Carey; Bandaranayaka-Mudiyanselage, Chandima-Bandara; Kang, Eunah; Adams, D Scott; Kappmeyer, Lowell S; Knowles, Donald P; McElwain, Terry F; Evermann, James F; Ueti, Massaro W; Scoles, Glen A; Lee, Stephen S; McGuire, Travis C

    2014-01-01

    The current study tested the hypothesis that removal of maltose binding protein (MBP) from recombinant antigen used for plate coating would improve the specificity of a commercial Anaplasma antibody competitive enzyme-linked immunosorbent assay (cELISA). The number of 358 sera with significant MBP antibody binding (≥30%I) in Anaplasma-negative herds was 139 (38.8%) when tested using the recombinant major surface protein 5 (rMSP5)-MBP cELISA without MBP adsorption. All but 8 of the MBP binders were rendered negative (Anaplasma-negative sera, which included the 139 sera with significant (≥30%I) MBP binding in the rMSP5-MBP cELISA without MBP adsorption, was positive. This resulted in an improved diagnostic specificity of 99.7%. The rMSP5-GST cELISA without MBP adsorption had comparable analytical sensitivity to the rMSP5-MBP cELISA with MBP adsorption and had 100% diagnostic sensitivity when tested with 135 positive sera defined by nested polymerase chain reaction. Further, the rMSP5-GST cELISA resolved 103 false-positive reactions from selected sera with possible false-positive reactions obtained using the rMSP5-MBP cELISA with MBP adsorption and improved the resolution of 29 of 31 other sera. In summary, the rMSP5-GST cELISA was a faster and simpler assay with higher specificity, comparable sensitivity, and improved resolution in comparison with the rMSP5-MBP cELISA with MBP adsorption.

  3. Qualification and application of a surface plasmon resonance-based assay for monitoring potential HAHA responses induced after passive administration of a humanized anti Lewis-Y antibody.

    Science.gov (United States)

    Szolar, O H J; Stranner, S; Zinoecker, I; Mudde, G C; Himmler, G; Waxenecker, G; Nechansky, A

    2006-06-16

    A sensitive, surface plasmon resonance (SPR)-based assay monitoring potential human-anti-human antibody (HAHA) reactions against the monoclonal antibody (mAb) IGN311 is presented. The latter is a fully humanized Lewis-Y carbohydrate specific mAb that is currently tested in a passive immune therapy approach in a clinical phase I trial. For the SPR experiments a BIACORE 3000 analyzer was used. The ligand IGN311 was covalently coupled to the carboxy-methylated dextran matrix of a CM5 research grade chip (BIACORE). In the course of a fully nested experimental design, a four parameter logistic equation was identified as appropriate calibration model ranging from 0.3 microg/mL (lower limit of quantitation, LLOQ) to 200 microg/mL (upper limit of quantitation, ULOQ) using an anti-idiotypic mAb ('HAHA mimic') as calibrator. The bias ranged from -2.4% to 5.5% and the intermediate precision expressed as 95% CI revealed values from 5.6% to 8.3%. Specificity was evaluated using six human serum matrices from healthy donors spiked with calibrator at the limit of quantitation (LOQ) with >80% of values being recovered with less than 25% relative error. The qualified assay was applied to monitor potentially induced HAHA reactivity in 11 patients from a clinical phase I trial with passively administered IGN311. Of the 11 patients, one high HAHA responder and several low responders were identified. Protein-G depletion experiments with human serum samples revealed that the observed response is predominantly caused by IgG binding to the ligand. The characteristics of these HAHA responses were all of the so-called 'Type I' which is defined by a peak response around day 15 that decreases from this point steadily suggesting that some kind of tolerance is established. Therefore, this type of HAHA response is regarded as non critical for the patient's safety.

  4. Development and validation of an indirect Enzyme-linked immunosorbent assay for the detection of antibodies against Schmallenberg virus in blood samples from ruminants.

    Science.gov (United States)

    van der Heijden, H M J F; Bouwstra, R J; Mars, M H; van der Poel, W H M; Wellenberg, G J; van Maanen, C

    2013-10-01

    To detect Schmallenberg virus (SBV) infections in ruminants and to perform SBV epidemiological studies a cost-effective serological test is required. For these purposes an indirect whole virus Enzyme-linked Immunosorbent Assay (ELISA) for detection of SBV specific antibodies in ruminant blood samples was developed. Schmallenberg virus antigen was produced by propagation on Vero cells, partly purified and coated onto ELISA plates. The indirect ELISA procedure included the subsequent incubation of diluted samples, protein-G-HRP conjugate and TMB substrate solution. Net Optical Densities (OD) values were calculated and expressed as a sample to positive percentage (S/P%) by comparison of the average net OD with the OD of the positive control. Validation of this assay was performed using 633 samples from SBV-free sheep, goats and cattle, and 141 samples from SBV suspect ruminants. The diagnostic specificity was 98.8%. Test results of 86 ruminant serum samples using both the SBV-ELISA and an SBV virus neutralization test (VNT), designated as the gold standard serological test for SBV, showed good correlation: at an S/P cut-off of 15% only one VNT positive sample tested negative in the SBV ELISA. The diagnostic sensitivity of the ELISA, relative to the VNT, was 98.8% (95% CI: 93.3-100.0%). The ELISA showed a high repeatability (cv=6.5%) and reproducibility (100% agreement). It was concluded that this ELISA is a suitable test method for the detection of SBV antibodies in sera from cows, sheep and, possibly, goats.

  5. Epidemiological, biological and histological characterization of patients with indeterminate third-generation recombinant immunoblot assay antibody results for hepatitis C virus.

    Science.gov (United States)

    Ríos, M; Diago, M; Rivera, P; Tuset, C; Cors, R; García, V; Carbonel, P; Gonzalez, C

    2006-03-01

    We studied the epidemiological, laboratory and histological characteristics of a group of patients with positive antibodies against hepatitis C virus (HCV) as determined by third-generation enzyme-linked immunosorbent assay (ELISA), and with indeterminate HCV antibody positivity as established by third-generation recombinant immunoblot assay (RIBA-3). The results obtained were compared with those recorded in a group of RIBA-3-positive patients. Both groups correspond to blood donors in whom the prevalence of hepatitis C is low. There were no statistically significant intergroup differences in mean age, or in the presence of infection risk factors. RNA positivity was much more frequent in the RIBA-positive group (71%vs 10%; P < 0.05), as was transaminase elevation during the 3 years of follow-up (54%vs 13%; P < 0.05). In 46% of the RIBA-indeterminate patients the liver biopsy proved normal, or only liver steatosis or minimal changes were detected, while 33% had persistent chronic hepatitis, and 21% showed active chronic hepatitis. A mean Knodell index score of 2.28 was recorded; 50% of the subjects showed no fibrosis, 46% grade 1 fibrosis (fibrous portal expansion), 4% grade 2 fibrosis (bridging fibrosis), and none grade 3 fibrosis (liver cirrhosis). In the RIBA-positive group, a greater percentage of patients had active chronic hepatitis, a greater Knodell index, and increased-grade fibrosis. It can be concluded that the RIBA-3-indeterminate group is epidemiologically similar to the RIBA-3-positive series, although with a lesser prevalence of laboratory test alterations, a lower viral replication index, and more likely to have benign disease - particularly in subjects without viral replication.

  6. Coproantigen detection in dogs experimentally and naturally infected with Echinococcus granulosus by a monoclonal antibody-based enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Malgor, R; Nonaka, N; Basmadjian, I; Sakai, H; Carámbula, B; Oku, Y; Carmona, C; Kamiya, M

    1997-12-01

    A sandwich ELISA for the detection of Echinococcus granulosus coproantigen in formalin and heat-treated faecal supernatants of dogs was developed. The assay used affinity-purified polyclonal antibodies obtained from rabbits hyperimmunised with E. granulosus excretory/secretory antigens and biotinylated monoclonal antibody EmA9 produced against adult E. multilocularis somatic extract. The test was sensitive to 7 ng and 2.3 ng of E. granulosus protein and carbohydrate/ml of faecal supernatant, respectively. Thirteen helminth-free dogs were infected with different amounts of E. granulosus protoscoleces and the presence of coproantigen was monitored during the prepatent period until day 35 post-infection, when they were necropsied. Faecal antigen levels started to rise above the normal range between days 10 and 20 post-infection, and typically peaked at the end of the experiment. All the dogs, bearing from 3 to 67,700 worms, showed positive values in the ELISA during the prepatent period. One dog experimentally infected with Taenia hydatigena metacestode and harbouring three worms, tested positive only after the prepatent period at day 52. The test was applied to 98 stray dogs. The ELISA detected all of four dogs naturally infected with E. granulosus, two dogs with patent infections of T. hydatigena and two dogs with no cestode infections, showing a sensitivity of 100% and a specificity of 96%.

  7. Validation of the World Health Organization Enzyme-Linked Immunosorbent Assay for the Quantitation of Immunoglobulin G Serotype-Specific Anti-Pneumococcal Antibodies in Human Serum.

    Science.gov (United States)

    Lee, Hyunju; Lim, Soo Young; Kim, Kyung Hyo

    2017-10-01

    The World Health Organization (WHO) enzyme-linked immunosorbent assay (ELISA) guideline is currently accepted as the gold standard for the evaluation of immunoglobulin G (IgG) antibodies specific to pneumococcal capsular polysaccharide. We conducted validation of the WHO ELISA for 7 pneumococcal serotypes (4, 6B, 9V, 14, 18C, 19F, and 23F) by evaluating its specificity, precision (reproducibility and intermediate precision), accuracy, spiking recovery test, lower limit of quantification (LLOQ), and stability at the Ewha Center for Vaccine Evaluation and Study, Seoul, Korea. We found that the specificity, reproducibility, and intermediate precision were within acceptance ranges (reproducibility, coefficient of variability [CV] ≤ 15%; intermediate precision, CV ≤ 20%) for all serotypes. Comparisons between the provisional assignments of calibration sera and the results from this laboratory showed a high correlation > 94% for all 7 serotypes, supporting the accuracy of the ELISA. The spiking recovery test also fell within an acceptable range. The quantification limit, calculated using the LLOQ, for each of the serotypes was 0.05-0.093 μg/mL. The freeze-thaw stability and the short-term temperature stability were also within an acceptable range. In conclusion, we showed good performance using the standardized WHO ELISA for the evaluation of serotype-specific anti-pneumococcal IgG antibodies; the WHO ELISA can evaluate the immune response against pneumococcal vaccines with consistency and accuracy. © 2017 The Korean Academy of Medical Sciences.

  8. Identification of specific antinuclear antibodies in dogs using a line immunoassay and enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Bremer, Hanna D; Lattwein, Erik; Renneker, Stefanie; Lilliehöök, Inger; Rönnelid, Johan; Hansson-Hamlin, Helene

    2015-12-15

    Circulating antinuclear antibodies (ANA) are commonly present in the systemic autoimmune disease Systemic Lupus Erythematosus (SLE) and in other systemic rheumatic diseases, in humans as well as in dogs. The indirect immunofluorescence (IIF)-ANA test is the standard method for detecting ANA. Further testing for specific ANA with immunoblot techniques or ELISAs is routinely performed in humans to aid in the diagnosis and monitoring of disease. Several specific ANA identified in humans have been identified also in suspected canine SLE but, in contrast to humans, investigation of autoantibodies in canine SLE is mainly restricted to the IIF-ANA test. Our aim was to identify both known and novel specific ANA in dogs and to investigate if different IIF-ANA patterns are associated with different specific ANA in dogs. Sera from 240 dogs with suspicion of autoimmune disease (210 IIF-ANA positive (ANA(pos)) and 30 IIF-ANA negative (ANA(neg))) as well as sera from 27 healthy controls were included. The samples were analysed with a line immunoassay, LIA (Euroline ANA Profile 5, Euroimmun, Lübeck, Germany) and four different ELISAs (Euroimmun). The ANA(pos) dogs were divided in two groups depending on the type of IIF-ANA pattern. Of the 210 ANA(pos) samples 68 were classified as ANA homogenous (ANA(H)) and 141 as ANA speckled (ANA(S)), one sample was not possible to classify. Dogs in the ANA(H) group had, compared to the other groups, most frequently high levels of anti-double stranded deoxyribonucleic acid (dsDNA) and anti-nucleosome ANA. Anti-dsDNA antibodies were confirmed in some dogs with the Crithidia luciliae indirect immunofluorescence test (CLIFT). The frequency of ANA(H) dogs with values above those observed in the healthy group was significantly higher compared to ANA(S) dogs for anti-dsDNA, anti-nucleosome, and anti-histone reactivity. Dogs in the ANA(S) group had, compared to the other groups, most frequently high levels of anti-ribonucleoproteins (RNP) and

  9. Identification of a high-affinity monoclonal antibody against ochratoxin A and its application in enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Zhang, Xian; Sun, Mengjiao; Kang, Yue; Xie, Hui; Wang, Xin; Song, Houhui; Li, Xiaoliang; Fang, Weihuan

    2015-11-01

    Ochratoxin A (OTA) is one of the most commonly occurring mycotoxins produced by some species of Aspergillus and can contaminate cereal and cereal products. A high-affinity anti-OTA monoclonal antibody (mAb) was generated from a hybridoma cell line 2D8 using splenocytes from a BALB/c mouse immunized with synthesized OTA-bovine serum albumin conjugate. The mAb 2D8 is specific with high affinity (3.75 × 10(9) L/M). An indirect competitive ELISA (ic-ELISA) was then developed using this mAb for quantitative determination of OTA in corn and feed samples. Using the optimized conditions, there was good linearity between OTA concentration and competitive inhibition (y = -0.6076x + 0.2441, R(2) = 0.9923) with the working range from 2.4 to 23.6 μg/kg, IC50 at 7.6 μg/kg and lower limit of detection at 1.4 μg/kg. The recovery rates in spiked samples were 91.2-110.3%. Of the 56 corn and feed samples, this ic-ELISA and a commercial kit both found the same 13 samples positive for OTA with good linear correlation between the two methods in OTA quantification (R(2) = 0.9706). We conclude that this ic-ELISA can be used for rapid and quantitative screening of corn and feed samples for the presence of OTA.

  10. The assay of thyrotropin receptor antibodies with human TSH/LH-CG chimeric receptor expressed on chinese hamster ovary cells

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Ka Hee; Kim, Chang Min [Korea Cancer Center Hospital, Seoul (Korea, Republic of)

    1996-12-01

    TSH/LH-CG chimera cDNA is transfected to CHO-K1 cell to obtain the chimeric receptor expressed on the cell surface. The optimal conditions for TSAb and TSBAb measurements are determined using chimeric receptors and under these conditions activity of TSAb and TSBAb in the sera of the Graves` patients. The results obtained are compared to those of TSAb assays using FRTL5 cells CHO-TSHR cells which have wild type human TSH receptor. The transfection procedure of chimeric receptor gene to CHO-K1 cells are on going. The optimal conditions for TSAb and TSBAb measurement using chimeric receptor will be determined after success of transfection procedure. If this study is successfully completed, not only the heterogeneity of Graves. IgG but also pathogenesis of Graves` disease will be elucidated. (author). 25 refs.

  11. The assay of thyrotropin receptor antibodies with human TSH/LH-CG chimeric receptor expressed on chinese hamster ovary cells

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Ka Hee; Kim, Chang Min [Korea Cancer Center Hospital, Seoul (Korea, Republic of)

    1996-12-01

    TSH/LH-CG chimera cDNA is transfected to CHO-K1 cell to obtain the chimeric receptor expressed on the cell surface. The optimal conditions for TSAb and TSBAb measurements are determined using chimeric receptors and under these conditions activity of TSAb and TSBAb in the sera of the Graves` patients. The results obtained are compared to those of TSAb assays using FRTL5 cells CHO-TSHR cells which have wild type human TSH receptor. The transfection procedure of chimeric receptor gene to CHO-K1 cells are on going. The optimal conditions for TSAb and TSBAb measurement using chimeric receptor will be determined after success of transfection procedure. If this study is successfully completed, not only the heterogeneity of Graves. IgG but also pathogenesis of Graves` disease will be elucidated. (author). 25 refs.

  12. Highly sensitive and reproducible immunoradiometric assay for total human renin using monoclonal antibodies, iodogen labelling and polystyrene star tubes

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, M.D.; Rasumussen, P.H.; Giese, J.

    1987-01-01

    A two-site immunoradiometric assay for total renin concentration in human plasma is described. A new type of polystyrene tubes with a special bottom geometry, so-called Star Tubes were used. The lower limit of detection was 2 microIU per ml and the working range from 2 to 2000 microIU per ml. The variation for duplicate determinations on standards and plasma samples was 2.7% and the day to day variation was 4.8%. No significant interferences or cross reactivities were identified. EDTA-plasma was analyzed after dilution with a phosphate buffer. Plasma samples from different patient categories were analyzed. The results were compared with those obtained by our substrate enrichment method after acid activation of the samples had taken place. A linear correlation (r = 0.990) between the results obtained with the two methods was found.

  13. A multilaboratory evaluation of a commercial enzyme-linked immunosorbent assay test for the detection of antibodies against Mycobacterium avium subsp. paratuberculosis in cattle.

    Science.gov (United States)

    Dargatz, David A; Byrum, Beverly A; Collins, Michael T; Goyal, Sagar M; Hietala, Sharon K; Jacobson, Richard H; Kopral, Christine A; Martin, Barbara M; McCluskey, Brian J; Tewari, Deepanker

    2004-11-01

    Five laboratories participated in a study to evaluate sources of variation in results from an enzyme-linked immunosorbent assay (ELISA) for antibodies against Mycobacterium avium subsp. paratuberculosis. Each laboratory repeatedly tested duplicates of a negative, positive (P), and high-positive (HP) serum sample, which were supplied by the United States Department of Agriculture: Animal and Plant Health Inspection Service: Veterinary Services, National Veterinary Services Laboratories, Ames, IA, on all 96-well microtiter plates when routinely testing other samples for M. avium subsp. paratuberculosis antibodies. These 3 sera were aliquoted and sent to the 5 participating laboratories. This study focused on variation in test results because of assay reagents and laboratory techniques and did not account for biologic variability associated with the time course of infection in cattle. Overall, results from 868 microtiter plates were used in the study. For each sample a sample-to-positive (S/P) ratio was calculated according to the manufacturer's directions. The S/ P ratio for the P sample ranged from 0.06 to 1.039 (mean = 0.466 and 0.484 for wells 1 and 2, respectively) and those for the HP sample ranged from 2.446 to 8.727 (mean = 4.027 and 3.980 for wells 1 and 2, respectively). The majority of the variation in S/P ratio for the P sample was attributed to kit lot (37.5%), followed by random (unexplained) error (27.0%), laboratory (18.3%), and kit lot by laboratory (11.9%). By eliminating plates in which the separation between negative and positive control ODs was less than 0.4, the proportion of variation attributed to laboratory was reduced markedly. These results confirm that there is variability in M. avium subsp. paratuberculosis ELISA results and that several sources contribute to the observed variability. The study gives a relative estimate of the contribution of various sources to the overall variability observed in the M. avium subsp. paratuberculosis ELISA

  14. A novel asymmetric-loop molecular beacon-based two-phase hybridization assay for accurate and high-throughput detection of multiple drug resistance-conferring point mutations in Mycobacterium tuberculosis.

    Science.gov (United States)

    Chen, Qinghai; Wu, Nan; Xie, Meng; Zhang, Bo; Chen, Ming; Li, Jianjun; Zhuo, Lisha; Kuang, Hong; Fu, Weiling

    2012-04-01

    The accurate and high-throughput detection of drug resistance-related multiple point mutations remains a challenge. Although the combination of molecular beacons with bio-immobilization technology, such as microarray, is promising, its application is difficult due to the ineffective immobilization of molecular beacons on the chip surface. Here, we propose a novel asymmetric-loop molecular beacon in which the loop consists of 2 parts. One is complementary to a target, while the other is complementary to an oligonucleotide probe immobilized on the chip surface. With this novel probe, a two-phase hybridization assay can be used for simultaneously detecting multiple point mutations. This assay will have advantages, such as easy probe availability, multiplex detection, low background, and high-efficiency hybridization, and may provide a new avenue for the immobilization of molecular beacons and high-throughput detection of point mutations.

  15. Validation of a Poisson-distributed limiting dilution assay (LDA) for a rapid and accurate resolution of multiclonal infections in natural Trypanosoma cruzi populations.

    Science.gov (United States)

    Ramírez, Juan David; Herrera, Claudia; Bogotá, Yizeth; Duque, María Clara; Suárez-Rivillas, Alejandro; Guhl, Felipe

    2013-02-15

    Trypanosoma cruzi is the causative agent of American trypanosomiasis, a complex zoonotic disease that affects more than 10million people in the Americas. Strains of this parasite possess a significant amount of genetic variability and hence can be divided into at least six discrete typing units (DTUs). The life cycle of this protist suggests that multiclonal infections may emerge due to the likelihood of contact of triatomine insects with more than 100 mammal species. To date, there have been a few studies on but no consensus regarding standardised methodologies to identify multiclonal infections caused by this parasite. Hence, the aim of this study was to develop and validate a limiting dilution assay (LDA) to identify multiclonal infections in T. cruzi populations by comparing the feasibility and reliability of this method with the widely applied solid phase blood agar (SPBA) methodology. We cloned reference strains belonging to three independent genotypes (TcI, TcII, and TcIV) and mixed infections (TcI+TcII) using LDA and SPBA; the comparison was conducted by calculating the feasibility and reliability of the methods employed. Additionally, we implemented LDA in strains recently isolated from Homo sapiens, Rhodnius prolixus, Triatoma venosa, Panstrongylus geniculatus, Tamandua tetradactyla, Rattus rattus, Didelphis marsupialis and Dasypus novemcinctus, with the aim of resolving multiclonal infections using molecular characterization employing SL-IR (spliced leader intergenic region of mini-exon gene), the 24Sα rDNA gene and microsatellite loci. The results reported herein demonstrate that LDA is an optimal methodology to distinguish T. cruzi subpopulations based on microsatellite markers by showing the absence of multiple peaks within a single locus. Conversely, SPBA showed patterns of multiple peaks within a single locus suggesting multiclonal events. The biological consequences of these results and the debate between multiclonality and aneuploidy are

  16. Assessment of Neutralising Activity of Colostrum-Derived, Polyclonal, Bovine Antibodies: Use of the J774A.1 Anthrax Lethal Toxin Cytototoxity Assay

    Science.gov (United States)

    2005-12-01

    Assessment of Neutralising Activity of Colostrum - Derived, Polyclonal, Bovine Antibodies: Use of the J774A.1 Anthrax Lethal Toxin...activity of colostrum -derived, polyclonal, bovine antibodies. Antibodies against lethal factor and protective antigen were found to protect...APPROVED FOR PUBLIC RELEASE Assessment of Neutralising Activity of Colostrum - Derived, Polyclonal, Bovine Antibodies: Use of the J774A.1

  17. An AS-PCR assay for accurate genotyping of FAD2A/FAD2B genes in peanuts (Arachis hypogaea L.

    Directory of Open Access Journals (Sweden)

    Yu, H. T.

    2013-09-01

    Full Text Available FAD2A and FAD2B are homoeologous genes from A and B genomes in cultivated peanuts (Arachis hypogaea L. encoding fatty acid desaturates which convert oleate to linoleate. To study the genetics of oleate and breed high oleate peanut cultivars, a simple allele specific-PCR (AS-PCR protocol for the accurate genotyping of FAD2A/FAD2B was developed to discriminate the wild and mutant allele of both genes (FAD2A 448 G > A and FAD2B 441_442insA. The results may serve to develop a feasible procedure for producing highly desired high oleate peanut cultivars through hybridization.FAD2A y FAD2B son genes homólogos de genomas A y B en cacahuete cultivado (Arachis hypogaea L. que codifican las desaturasas de ácidos grasos que convierten oleato a linoleato. Para estudiar la genética de las variedades mejoradas de cacahuete alto oleato, fue desarrollado un protocolo sencillo del alelo específico PCR-(AS-PCR para la determinación precisa del genotipo de FAD2A/FAD2B y discriminar el alelo silvestre y el mutante de ambos genes (FAD2A 448 G > A y FAD2B 441_442insA. Los resultados pueden servir para desarrollar un procedimiento viable para la producción de cultivares deseados de cacahuetes alto oleato a través de hibridación.

  18. Assay of neutralizing antibody against variola virus by the degree of focus reduction on HeLa cell cultures and its application to revaccination with smallpox vaccines of various potencies.

    Science.gov (United States)

    Kitamura, T; Shinjo, N

    1972-01-01

    A method for assaying neutralizing antibody against variola virus was established by focus counting on HeLa cell cultures. The ND(50) titre, i.e., the serum dilution endpoint to give a 50% reduction in the number of foci, was determined with excellent reproducibility.Groups of students 19-20 years of age were revaccinated by the multiple pressure method with serial 10-fold dilutions of a smallpox vaccine and their neutralizing antibody response was assayed by the focus counting assay system and was related to the local skin reactions on the seventh day after inoculation and to the potency of the vaccine administered. There was a significant rise in the antibody level even after inoculation with a vaccine whose potency was as low as 1.3 x 10(5) pock-forming units/ml. In general, the rise in the log antibody level was proportional to the diameter of the reddening, but a significant rise was found among individuals who had no detectable skin reaction. The skin reaction was greater among individuals with a lower initial antibody level when the vaccine administered had a potency lower than 1.3 x 10(6) pock-forming units/ml.

  19. Measurement of thyrotropin receptor antibodies (TRAK) with a second generation assay in patients with Graves' disease; Die Bestimmung von Thyreotropin-Rezeptor-Antikoerpern (TRAK) mit einem Assay der zweiten Generation bei Patienten mit Morbus Basedow

    Energy Technology Data Exchange (ETDEWEB)

    Zoephel, K.; Wunderlich, G.; Franke, W.G. [Klinik und Poliklinik fuer Nuklearmedizin, Technische Univ. Dresden (Germany); Koch, R. [Inst. fuer Medizinische Informatik und Biometrie, Technische Univ. Dresden (Germany)

    2000-06-01

    Aim: The detection of TSH-receptor-antibodies (TRAb) in patients (pts) with Graves' disease (GD) is routinely used in nuclear medicine laboratories. It is performed by commercial, porcine radioreceptorassays (RRA) measuring TSH binding inhibitory activity. A second generation assay using the human, recombinant TSH-receptor was developed during the last years. The manufacturer composed this new assay as a coated tube RRA (CT RRA) and claimed a higher sensitivity for GD. Methods: TRAb was measured in 207 pts with various thyroid disorders and 205 healthy controls using the new coated tube RRA (Fa. B.R.A.H.M.S. Diagnostica GmbH, Berlin, Germany) as well as a conventional RRA (Fa. Medipan Diagnostica GmbH, Selchow, Germany): 60 pts suffering from GD showing a relapse after anti-thyroid drug treatment and before radioiodine therapy, 109 pts with disseminated autonomia (DA) and 38 pts suffering from Hashimoto's thyroiditis. A ROC-analysis was performed to find the optimal decision threshold level for positivity. Results: We found 42/60 TRAb-positive pts with GD in the established RRA (threshold 6 U/L) and 52/60 in the CT RRA, respectively. The sensitivity increased from 70% (RRA) to 86,7% (CT RRA). The CT RRA found 2 false positives (one Hashimoto's and one healthy control) and the RRA detected 3 Hashimoto's and 2 healthy controls as false positive. Conclusion: The increased sensitivity of CT RRA for GD provides an advantage compared to conventional RRA, especially in GD-patients relapsing afte antithyroid drug treatment. Functional sensitivity and Interassayvariation of CT RRA are very precisely compared to conventional RRA. Handling of the new assay is also improved. (orig.) [German] Ziel: Die Bestimmung der TSH-Rezeptorantikoerper (TRAK) bei Patienten mit Morbus Basedow ist fester Bestandteil der nuklearmedizinischen In-vitro-Diagnostik. Seit kurzem ist die Bestimmung mit einem TRAK-Assay moeglich, bei dem im Gegensatz zu den herkoemmlichen

  20. Localization and Distribution of 'Candidatus Liberibacter asiaticus' in Citrus and Periwinkle by Direct Tissue Blot Immuno Assay with an Anti-OmpA Polyclonal Antibody.

    Directory of Open Access Journals (Sweden)

    Fang Ding

    Full Text Available 'Candidatus Liberibacter asiaticus' (CaLas, a non-cultured member of the α-proteobacteria, is the causal agent of citrus Huanglongbing (HLB. Due to the difficulties of in vitro culture, antibodies against CaLas have not been widely used in studies of this pathogen. We have used an anti-OmpA polyclonal antibody based direct tissue blot immunoassay to localize CaLas in different citrus tissues and in periwinkle leaves. In citrus petioles, CaLas was unevenly distributed in the phloem sieve tubes, and tended to colonize in phloem sieve tubes on the underside of petioles in preference to the upper side of petioles. Both the leaf abscission zone and the junction of the petiole and leaf midrib had fewer CaLas bacteria compared to the main portions of the petiole and the midribs. Colonies of CaLas in phloem sieve tubes were more frequently found in stems with symptomatic leaves than in stems with asymptomatic leaves with an uneven distribution pattern. In serial sections taken from the receptacle to the peduncle, more CaLas were observed in the peduncle sections adjacent to the stem. In seed, CaLas was located in the seed coat. Many fewer CaLas were found in the roots, as compared to the seeds and petioles when samples were collected from trees with obvious foliar symptoms. The direct tissue blot immuno assay was adapted to whole periwinkle leaves infected by CaLas. The pathogen was distributed throughout the lateral veins and the results were correlated with results of qPCR. Our data provide direct spatial and anatomical information for CaLas in planta. This simple and scalable method may facilitate the future research on the interaction of CaLas and host plant.

  1. [Immunofluorescence assay with Crithidia luciliae for the detection of anti-DNA antibodies. Atypical images and their relationship with Chagas' disease and leishmaniasis].

    Science.gov (United States)

    Griemberg, Gloria; Ferrarotti, Nidia F; Svibel, Graciela; Ravelli, Maria R; Taranto, Nestor J; Malchiodi, Emilio L; Pizzimenti, Maria C

    2006-01-01

    Anti-native DNA antibodies can be detected by indirect immunofluorescence assay with Crithidia luciliae, displaying an annular image due to a kinetoplast containing double stranded DNA. Other structures such as membrane, flagellum and basal corpuscle can be stained as well, showing what is called atypical fluorescent images. As C. luciliae belongs to the Trypanosomatidae family, which include the human pathogens Trypanosoma cruzi and Leishmania spp., it was considered that these atypical images could be caused by cross-reactions. Serological studies for Chagas' disease were performed in 105 serum samples displaying atypical images. Sixty four percent of the samples from non endemic and 78.3% from endemic areas for Chagas' disease showed fluorescence in both, membrane and flagellum (joint image). Fifty samples from normal blood donors and 57 samples from patients with conective tissue diseases were tested with C. luciliae. None of them presented the joint image except for two patients with lupus who were also chagasic. In addition, 54 samples from chagasic patients were studied and all of them presented the joint image. We also studied 46 samples from patients with leishmaniasis from whom 28 were coinfected with T. cruzi. The joint image was observed in 88.0% of the samples with leishmaniasis and in 89.3% of the co-infected samples. The results suggest that C. luciliae could be used as an economical, and of low risk, alternative substrate for the serological diagnosis of Chagas' disease, even though it does not discriminate for Leishmania spp. infection. This study also suggests that whenever atypical images are observed in C. luciliae during the search for anti-DNA antibodies, it would be convenient to submit the patient to clinical and serological tests for the diagnosis of leishmaniosis and Chagas' disease.

  2. Localization and Distribution of 'Candidatus Liberibacter asiaticus' in Citrus and Periwinkle by Direct Tissue Blot Immuno Assay with an Anti-OmpA Polyclonal Antibody.

    Science.gov (United States)

    Ding, Fang; Duan, Yongping; Paul, Cristina; Brlansky, Ronald H; Hartung, John S

    2015-01-01

    'Candidatus Liberibacter asiaticus' (CaLas), a non-cultured member of the α-proteobacteria, is the causal agent of citrus Huanglongbing (HLB). Due to the difficulties of in vitro culture, antibodies against CaLas have not been widely used in studies of this pathogen. We have used an anti-OmpA polyclonal antibody based direct tissue blot immunoassay to localize CaLas in different citrus tissues and in periwinkle leaves. In citrus petioles, CaLas was unevenly distributed in the phloem sieve tubes, and tended to colonize in phloem sieve tubes on the underside of petioles in preference to the upper side of petioles. Both the leaf abscission zone and the junction of the petiole and leaf midrib had fewer CaLas bacteria compared to the main portions of the petiole and the midribs. Colonies of CaLas in phloem sieve tubes were more frequently found in stems with symptomatic leaves than in stems with asymptomatic leaves with an uneven distribution pattern. In serial sections taken from the receptacle to the peduncle, more CaLas were observed in the peduncle sections adjacent to the stem. In seed, CaLas was located in the seed coat. Many fewer CaLas were found in the roots, as compared to the seeds and petioles when samples were collected from trees with obvious foliar symptoms. The direct tissue blot immuno assay was adapted to whole periwinkle leaves infected by CaLas. The pathogen was distributed throughout the lateral veins and the results were correlated with results of qPCR. Our data provide direct spatial and anatomical information for CaLas in planta. This simple and scalable method may facilitate the future research on the interaction of CaLas and host plant.

  3. Prevalence estimation of tick-borne encephalitis virus (TBEV) antibodies in dogs from Finland using novel dog anti-TBEV IgG MAb-capture and IgG immunofluorescence assays based on recombinant TBEV subviral particles.

    Science.gov (United States)

    Levanov, Lev; Vera, Cristina Pérez; Vapalahti, Olli

    2016-07-01

    Tick-borne encephalitis (TBE) is one of the most dangerous human neurological infections occurring in Europe and Northern parts of Asia with thousands of cases and millions vaccinated against it. The risk of TBE might be assessed through analyses of the samples taken from wildlife or from animals which are in close contact with humans. Dogs have been shown to be a good sentinel species for these studies. Serological assays for diagnosis of TBE in dogs are mainly based on purified and inactivated TBEV antigens. Here we describe novel dog anti-TBEV IgG monoclonal antibody (MAb)-capture assay which is based on TBEV prME subviral particles expressed in mammalian cells from Semliki Forest virus (SFV) replicon as well as IgG immunofluorescence assay (IFA) which is based on Vero E6 cells transfected with the same SFV replicon. We further demonstrate their use in a small-scale TBEV seroprevalence study of dogs representing different regions of Finland. Altogether, 148 dog serum samples were tested by novel assays and results were compared to those obtained with a commercial IgG enzyme immunoassay (EIA), hemagglutination inhibition test and IgG IFA with TBEV infected cells. Compared to reference tests, the sensitivities of the developed assays were 90-100% and the specificities of the two assays were 100%. Analysis of the dog serum samples showed a seroprevalence of 40% on Åland Islands and 6% on Southwestern archipelago of Finland. In conclusion, a specific and sensitive EIA and IFA for the detection of IgG antibodies in canine sera were developed. Based on these assays the seroprevalence of IgG antibodies in dogs from different regions of Finland was assessed and was shown to parallel the known human disease burden as the Southwestern archipelago and Åland Islands in particular had considerable dog TBEV antibody prevalence and represent areas with high risk of TBE for humans.

  4. A rapid and accurate 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide colorimetric assay for quantification of bacteriocins with nisin as an example

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The objective of this study is to propose a more accurate and faster MTT [3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide] colorimetric assay (MCA) for quantitative measurement of polypeptide bacteriocins in solutions with nisin as an example. After an initial incubation of nisin and indicator bacterium Micrococcus luteus NCIB 8166 in tubes, MTT was added for another incubation period. After that, nisin was quantified by estimating the number of viable bacteria based on measuring the amount of purple formazan produced by cleavage of yellow tetrazolium salt MTT. Then MCA was compared to a standard agar diffusion assay (ADA). The results suggested a high correlation coefficient (r2=0.975±0.004) between optical density (OD) and the inhibitory effect of nisin on a bacterial strain Micrococcus luteus NCIB 8166 at a range of 0.125~32 IU/ml.The MCA described in this study was very quick. Quantification of nisin took only 7~8 h and the detection limit was at the level of 0.125 IU/ml when compared to 12 IU/ml and 24~28 h for ADA. The MCA provides an accurate and rapid method for quantification of nisin in solutions and is expected to be used for quantification of other antimicrobial substances.

  5. Development and Characterization of Monoclonal Antibodies to Yellow Fever Virus and Application in Antigen Detection and IgM Capture Enzyme-Linked Immunosorbent Assay.

    Science.gov (United States)

    Adungo, Ferdinard; Yu, Fuxun; Kamau, David; Inoue, Shingo; Hayasaka, Daisuke; Posadas-Herrera, Guillermo; Sang, Rosemary; Mwau, Matilu; Morita, Kouichi

    2016-08-01

    Yellow fever (YF) is an acute hemorrhagic viral infection transmitted by mosquitoes in Africa and South America. The major challenge in YF disease detection and confirmation of outbreaks in Africa is the limited availability of reference laboratories and the persistent lack of access to diagnostic tests. We used wild-type YF virus sequences to generate recombinant envelope protein in an Escherichia coli expression system. Both the recombinant protein and sucrose gradient-purified YF vaccine virus 17D (YF-17D) were used to immunize BALB/c mice to generate monoclonal antibodies (MAbs). Eight MAbs were established and systematically characterized by indirect enzyme-linked immunosorbent assay (ELISA), Western blot analysis, and immunofluorescence assay (IFA). The established MAbs showed strong reactivity with wild-type YF virus and recombinant protein with no detectable cross-reactivity to dengue virus or Japanese encephalitis virus. Epitope mapping showed strong binding of three MAbs to amino acid positions 1 to 51, while two MAbs mapped to amino acid positions 52 to 135 of the envelope protein. The remaining three MAbs did not show reactivity to envelope fragments. The established MAbs exert no neutralization against wild-type YF and 17D viruses (titer of <10 for both strains). The applicability of MAbs 8H3 and 3F4 was further evaluated using IgM capture ELISA. A total of 49 serum samples were analyzed, among which 12 positive patient and vaccinee samples were correctly identified. Using serum samples that were 2-fold serially diluted, the IgM capture ELISA was able to detect all YF-positive samples. Furthermore, MAb-based antigen detection ELISA enabled the detection of virus in culture supernatants containing titers of about 1,000 focus-forming units.

  6. Diagnostic efficacy of monoclonal antibody based sandwich enzyme linked immunosorbent assay (ELISA for detection of Fasciola gigantica excretory/secretory antigens in both serum and stool

    Directory of Open Access Journals (Sweden)

    Zoheiry Mona K

    2011-09-01

    Full Text Available Abstract Background This research was carried out to develop a reliable monoclonal antibody (MoAb-based sandwich enzyme linked immunosorbent assay (ELISA for the diagnosis of active Fasciola gigantica infection in both serum and stool for comparative purposes. Methods From a panel of MoAbs raised against F. gigantica excretory/secretory antigens (ES Ags, a pair (12B/11D/3F and 10A/9D/10G was chosen due to its high reactivity and strict specificity to F. gigantica antigen by indirect ELISA. Results The two MoAbs were of the IgG1 and IgG2a subclasses, respectively. Using SDS-PAGE and EITB, the selected MoAbs recognized 83, 64, 45 and 26 kDa bands of ES Ags. The lower detection limit of ELISA assay was 3 ng/ml. In stool, the sensitivity, specificity and diagnostic efficacy of ELISA was 96%, 98.2 and 97.1%; while in serum they were 94%, 94.6% and 94.3%, respectively. Moreover, a positive correlation was found between ova count in stool of F. gigantica infected patients and the OD readings of ELISA in both stool and serum samples (r = 0.730, p Conclusions These data showed that the use of MoAb-based sandwich ELISA for the detection of F. gigantica coproantigens in stool specimens was superior to serum samples; it provides a highly efficient, non-invasive technique for the diagnosis of active F. gigantica infection.

  7. Application of the fluorescence polarization assay for detection of caprine antibodies to Brucella melitensis in areas of high prevalence and widespread vaccination.

    Science.gov (United States)

    Ramírez-Pfeiffer, C; Nielsen, K; Smith, P; Marín-Ricalde, F; Rodríguez-Padilla, C; Gomez-Flores, R

    2007-03-01

    The screening Rose Bengal test (RBT), the buffered plate agglutination test (BPAT), and the confirmatory complement fixation test (CFT) are currently approved by the World Organization for Animal Health (OIE) for diagnosis of goat brucellosis. However, RBT (at 3% or 8% cell concentration) is known to be affected by vaccinal antibodies. In the present study, Mexican and Canadian OIE tests were compared with the fluorescence polarization assay (FPA), alone or in combination, using indirect and competitive enzyme-linked immunosorbent assays as classification variables for goat sera obtained from an area of high prevalence and widespread vaccination. The relative sensitivities and specificities were, respectively, 99.7% and 32.5% for RBT3, 92.8% and 68.8% for RBT8, 98.4% and 84.8% for Canadian CFT, 83.7% and 65.5% for Mexican CFT, and 78.1% and 89.3% for FPA. The use of FPA as the confirmatory test in combination with other tests significantly increased the final specificities of the screening tests alone; BPAT, RBT3, and RBT8 plus FPA resulted in final specificities of 90%, 91.2%, and 91.3%, respectively, whereas for the combinations RBT3 plus Mexican CFT, RBT8 plus Mexican CFT, and BPAT plus Canadian CFT, specificities were 65.5%, 63.2%, and 91.7%, respectively. We suggest that FPA may be routinely applied as an adaptable screening test for diagnosis of goat brucellosis and as a confirmatory test for screening test series. Some advantages of FPA are that its cutoff can be adjusted to improve its sensitivity or specificity, it is a low-cost and easy-to-perform test of choice when specificity is relevant or when an alternative confirmatory test is not available, and it is not affected by vaccination, thus reducing the number of misdiagnosed and killed goats.

  8. Guidelines of the Office International des Epizooties for laboratory quality evaluation, for international reference standards for antibody assays and for laboratory proficiency testing.

    Science.gov (United States)

    1998-08-01

    Three guidelines, adopted by the International Committee of the Office International des Epizooties (OIE), have been combined for publication in a single document. The Guidelines for evaluating laboratory quality (adopted in 1995) form part of the OIE Guidelines for evaluating Veterinary Services. General requirements for equipment, staffing and management of laboratories are outlined. The guidelines for international reference standards for antibody assays (adopted in 1998) provide general rules governing the preparation of immune sera by OIE Reference Laboratories. A data sheet should accompany each preparation dispatched from the laboratory, and details are given of the information to be contained in the data sheet. The guidelines are to be used in conjunction with the OIE Manual of standards for diagnostic tests and vaccines. Guidelines on the proficiency of laboratory testing (adopted in 1996) describe how the operation of a laboratory can be assessed by inter-laboratory testing, and by voluntary participation in an accreditation (quality assurance) audit, operated by an independent authority. Criteria for assessing serological testing are provided.

  9. Cross-reactivity of antibodies with phenolic compounds in pistachios during quantification of ochratoxin A by commercial enzyme-linked immunosorbent assay kits.

    Science.gov (United States)

    Lee, Hyun Jung; Meldrum, Alexander D; Rivera, Nicholas; Ryu, Dojin

    2014-10-01

    Ochratoxin A (OTA), a nephrotoxic mycotoxin, naturally occurs in wide range of agricultural commodities. Typical screening of OTA involves various enzyme-linked immunosorbent assay (ELISA) methods. Pistachio (Pistacia vera L.) is a rich source of phenolic compounds that may result in a false positive due to structural similarities to OTA. The present study investigated the cross-reactivity profiles of phenolic compounds using two commercial ELISA test kits. High-performance liquid chromatography was used to confirm the concentration of OTA in the pistachio samples and compared with the results obtained from ELISA. When the degree of interaction and 50 % inhibitory concentration of phenolic compounds were determined, the cross-reactivity showed a pattern similar to that observed with the commercial ELSIA kits, although quantitatively different. In addition, the degree of interaction increased with the increasing concentration of phenolic compounds. The ELISA value had stronger correlations with the content of total phenolic compound, gallic acid, and catechin (R(2) = 0.757, 0.732, and 0.729, respectively) compared with epicatechin (R(2) = 0.590). These results suggest that phenolic compounds in pistachio skins may cross-react with the OTA antibody and lead to a false positive or to an overestimation of OTA concentration in ELISA-based tests.

  10. The effect of immunoscintigraphy with monoclonal antibodies on assays of hormones and tumor markers. This is not the end of the matter!

    NARCIS (Netherlands)

    J.A.M.J.L. Janssen (Joseph); P.J. Blankestijn (Peter); R. Docter (Roel); B.G. Blijenberg (Bert); S.W.J. Lamberts (Steven); E.P. Krenning (Eric)

    1989-01-01

    textabstractThe use of monoclonal antibodies in medicine for in-vivo diagnostic methods and for therapeutic purposes will increase in the future. Although monoclonal antibodies possess a high specificity, the animal origin of these antibodies remains a problem. Repeated administrat

  11. Surface plasmon resonance-enhanced fluorescence implementation of a single-step competition assay: demonstration of fatty acid measurement using an anti-fatty acid monoclonal antibody and a Cy5-labeled fatty acid.

    Science.gov (United States)

    Vareiro, Margarida M L M; Tranchant, Isabelle; Maplin, Sandra; Zak, Kris; Gani, M M; Slevin, Christopher J; Hailes, Helen C; Tabor, Alethea B; Cameron, Petra J; Jenkins, A Toby A; Williams, David E

    2008-06-15

    The development of a single-step, separation-free method for measurement of low concentrations of fatty acid using a surface plasmon resonance-enhanced fluorescence competition assay with a surface-bound antibody is described. The assay behavior was unexpectedly complex. A nonlinear coverage-dependent self-quenching of emission from surface-bound fluorescent label was deduced from the response kinetics and attributed to a surface plasmon-mediated energy transfer between adsorbed fluorophores, modified by the effects of plasmon interference. Principles of assay design to avoid complications from such effects are discussed. An anti-fatty acid mouse monoclonal antibody reacting to the alkyl chain was prepared and supported on a gold chip at a spacing appropriate for surface-plasmon field-enhanced fluorescence spectroscopy (SPEFS), by applying successively a self-assembled biotinylated monolayer, then streptavidin, then biotinylated protein A, and then the antibody, which was crosslinked to the protein A. Synthesis of a fluorescently (Cy5) tagged C-11 fatty acid is reported. SPEFS was used to follow the kinetics of the binding of the labeled fatty acid to the antibody, and to implement a competition assay with free fatty acid (undecanoic acid), sensitive at the 1 microM scale, a sensitivity limit caused by the low affinity of antibodies for free fatty acids, rather than the SPEFS technique itself. Free fatty acid concentration in human serum is in the range 0.1-1mM, suggesting that this measurement approach could be applied in a clinical diagnostic context. Finally, a predictive, theoretical model of fatty acid binding was developed that accounted for the observed "overshoot" kinetics.

  12. Use of complement binding assays to assess the efficacy of antibody mediated rejection therapy and prediction of graft survival in kidney transplantation.

    Science.gov (United States)

    Ramon, Daniel S; Huang, Yihung; Zhao, Lili; Rendulic, TrisAnn; Park, Jeong M; Sung, Randall S; Samaniego, Milagros

    2017-02-01

    The Luminex® single antigen bead assay (SAB) is the method of choice for monitoring the treatment for antibody-mediated rejection (AMR). A ⩾50% reduction of the dominant donor-specific antibody (IgG-DSA) mean fluorescence intensity (MFI) has been associated with improved kidney allograft survival, and C1q-fixing DSA activity is associated with poor outcomes in patients with AMR. We aimed to investigate if C1q-DSA can be used as a reliable predictor of response to therapy and allograft survival in patients with biopsy-proven AMR. We tested pre- and post-treatment sera of 30 kidney transplant patients receiving plasmapheresis and low-dose IVIG for biopsy-proven AMR. IgG-DSA and C1q-DSA MFI were measured and correlated with graft loss or survival. Patients were classified as nonresponders (NR) when treatment resulted in <50% reduction in MFI of IgG-DSA and/or C1q-DSA was detectable following therapy. Differences in the percentage of patients deemed NR depended upon the end-point criterion (73% by reduction in IgG-DSA MFI vs. 50% by persistent C1q-DSA activity). None of the seven patients with <50% reduction of IgG-DSA but non-detectable C1q-DSA-fixing activity after therapy experienced graft loss, suggesting that C1q-DSA activity may better correlate with response. Reduction of C1q-DSA activity predicted graft survival better than IgG-DSA in the univariate Cox analysis (20.1% vs. 5.9% in NR; log-rank P-value=0.0147). A rapid reduction of DSA concentration below the threshold required for complement activation is associated with better graft survival, and C1q-DSA is a better predictor of outcomes than IgG-DSA MFI reduction. Copyright © 2016 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.

  13. Evaluation of enzyme-linked immunosorbent assays and a haemagglutination inhibition tests for the detection of antibodies to Newcastle disease virus in village chickens using a Bayesian approach.

    Science.gov (United States)

    Chaka, H; Thompson, P N; Goutard, F; Grosbois, V

    2015-04-01

    Newcastle disease (ND) is an endemic disease in village chickens in Ethiopia with substantial economic importance. The sensitivity (Se) and specificity (Sp) of a blocking enzyme-linked immunosorbent assay (bELISA, Svanova Biotech), indirect ELISA (iELISA, Laboratoire Service International) and haemagglutination inhibition (HI) test for ND virus (NDV) antibody detection were evaluated in a Bayesian framework in the absence of a gold standard test, on sera collected from unvaccinated chickens kept under the village production system in household flocks and at markets in two woredas (i.e. districts) of the Eastern Shewa zone, Ethiopia. The outcomes of the iELISA test differed dramatically from those of the two other tests with 92% of the samples testing positive as compared with less than 15% for bELISA and HI. iELISA results were also inconsistent with previous estimations of Newcastle serological prevalence. The information provided by the iELISA test was thus considered as highly unreliable, probably due to an extremely low specificity, and thus not considered in the Bayesian models aiming at estimating serological prevalence and test performance parameters. Bayesian modelling of HI and bELISA test results suggested that bELISA had both the highest Se (86.6%; 95% posterior credible interval (PCI): 61.8%; 98.5%), and the highest Sp (98.3%; 95% PCI: 97.2%; 99.5%), while HI had a Se of 80.2% (95% PCI: 59.1%; 94.3%), and a Sp of 96.1% (95% PCI: 95.1%; 97.4%). Model selection and the range of the posterior distribution of the correlation between bELISA and HI test outcomes for truly seropositive animals (median at 0.461; PCI: -0.055; 0.894) suggested a tendency for bELISA and HI to detect the same truly positive animals and to fail to detect the same truly positive animals. The use of bELISA in screening and surveillance for NDV antibodies is indicated given its high Se and Sp, in addition to its ease of automation to handle large numbers of samples compared to HI. The

  14. Error in anti-DNA antibody radioimmunoassay after gallium scanning

    Energy Technology Data Exchange (ETDEWEB)

    Torretti, D.; Rooney, P.; Williams, G.; Decker, J.L.

    1977-03-01

    Significant interference with the accurate measurement of anti-DNA antibodies occurs after gallium-67 scanning. The observed effect is dependent on the radioimmunoassay used. False-negative results are observed with a modified Farr assay whereas false-positive results are noted in the millipore filter assay. These spurious values are the result of persistent radioactivity in the patients' sera after administration of /sup 67/Ga citrate.

  15. Identification of an immunodominant epitope in glycoproteins B and G of herpes simplex viruses (HSVs) using synthetic peptides as antigens in assay of antibodies to HSV in herpes simplex encephalitis patients.

    Science.gov (United States)

    Bhullar, S S; Chandak, N H; Baheti, N N; Purohit, H J; Taori, G M; Daginawala, H F; Kashyap, R S

    2014-01-01

    Herpes simplex encephalitis (HSE) is a severe viral infection of the central nervous system (CNS). Assay of antibody response is widely used in diagnostics of HSE. The aim of this study was to identify an immunodominant epitope determining the antibody response to herpes simplex viruses (HSVs) in cerebrospinal fluid (CSF) of HSE patients. The synthetic peptides that resembled type-common as well as type-specific domains of glycoproteins B (gB) and G (gG) of these viruses were evaluated for binding with IgM and IgG antibodies in CSF samples from HSE and non-HSE patients in ELISA. The QLHDLRF peptide, derived from gB of HSV was found to be an immunodominant epitope in the IgM and IgG antibody response. The patients with confirmed and suspected HSE showed in ELISA against this peptide 26% and 23% positivities for IgM, 43% and 37% positivities for IgG and 17% and 15% for both IgM and IgG antibodies, respectively. The total positivities of 86% and 75% for both IgM and IgG antibodies were obtained in the patients with confirmed and suspected HSE, respectively. These results demonstrate that a synthetic peptide-based diagnostics of HSE can be an efficient and easily accessible alternative. This is the first report describing the use of synthetic peptides derived from HSVs in diagnostics of HSE using patientsʹ CSF samples.

  16. Development and evaluation of an indirect enzyme-linked immunosorbent assay for the detection of antibodies against Campylobacter fetus in cattle.

    Science.gov (United States)

    Zhao, Hailing; Liu, Huifang; Du, Yanfen; Liu, Siguo; Ni, Hongbo; Wang, Yong; Wang, Chunlai; Si, Wei; Yang, Jinguo; Ling, Jingkai

    2010-06-01

    Campylobacteriosis is a zoonosis that occurs worldwide. Infection with Campylobacter fetus (C. fetus) causes infertility and abortion in sheep and cattle. The current study focuses on the SapA gene of C. fetus that encodes surface array proteins and plays an important role in the virulence of C. fetus. The SapA-N (1398bp) and SapA-C (1422bp) fragments were amplified from the C. fetusSapA gene using polymerase chain reaction (PCR), and the corresponding recombinant proteins rSapA-N and rSapA-C were expressed in Escherichia. coli BL21 cells. Results of Western blotting and enzyme-linked immunosorbent assay (ELISA) showed that the immunological activity of rSapA-N was higher than that of rSapA-C (PELISA for detecting antibodies against C. fetus. The diagnostic criteria were as follows: S/P0.45: positive; S/PS/P0.4: suspected. The specificity and sensitivity of our method were 94.3% and 88.6%, respectively. Moreover, no cross-reactions were observed between rSapA-N and serum samples that were positive for other bovine bacterial pathogens diseases such as Mycobacterium avium subspecies paratuberculosis. One hundred and two serum samples from cows that had experienced abortion were tested. Four and 2 C. fetus-positive serum samples were found among the 70 bovine brucellosis-positive samples and the 32 infectious bovine rhinotracheitis (IBR)-positive samples, respectively. The findings suggest that the rSapA-N-based ELISA method has immense potential in future applications. Copyright 2009 Elsevier Ltd. All rights reserved.

  17. Rapid and simultaneous detection of human hepatitis B virus and hepatitis C virus antibodies based on a protein chip assay using nano-gold immunological amplification and silver staining method

    Directory of Open Access Journals (Sweden)

    Wan Zhixiang

    2005-07-01

    Full Text Available Abstract Background Viral hepatitis due to hepatitis B virus and hepatitis C virus are major public health problems all over the world. Traditional detection methods including polymerase chain reaction (PCR-based assays and enzyme-linked immunosorbent assays (ELISA are expensive and time-consuming. In our assay, a protein chip assay using Nano-gold Immunological Amplification and Silver Staining (NIASS method was applied to detect HBV and HCV antibodies rapidly and simultaneously. Methods Chemically modified glass slides were used as solid supports (named chip, on which several antigens, including HBsAg, HBeAg, HBcAg and HCVAg (a mixture of NS3, NS5 and core antigens were immobilized respectively. Colloidal nano-gold labelled staphylococcal protein A (SPA was used as an indicator and immunogold silver staining enhancement technique was applied to amplify the detection signals, producing black image on array spots, which were visible with naked eyes. To determine the detection limit of the protein chip assay, a set of model arrays in which human IgG was spotted were structured and the model arrays were incubated with different concentrations of anti-IgG. A total of 305 serum samples previously characterized with commercial ELISA were divided into 4 groups and tested in this assay. Results We prepared mono-dispersed, spherical nano-gold particles with an average diameter of 15 ± 2 nm. Colloidal nano-gold-SPA particles observed by TEM were well-distributed, maintaining uniform and stable. The optimum silver enhancement time ranged from 8 to 12 minutes. In our assay, the protein chips could detect serum antibodies against HBsAg, HBeAg, HBcAg and HCVAg with the absence of the cross reaction. In the model arrays, the anti-IgG as low as 3 ng/ml could be detected. The data for comparing the protein chip assay with ELISA indicated that no distinct difference (P > 0.05 existed between the results determined by our assay and ELISA respectively. Conclusion

  18. A simple, rapid and reliable enzyme-linked immunosorbent assay for the detection of bovine virus diarrhoea virus (BVDV) specific antibodies in cattle serum, plasma and bulk milk

    NARCIS (Netherlands)

    Kramps, J.A.; Maanen, van C.; Wetering, van de G.; Stienstra, G.; Quak, S.; Brinkhof, J.; Ronsholt, L.; Nylin, B.

    1997-01-01

    To detect Bovine Virus Diarrhoea Virus (BVDV)-specific antibodies in cattle serum, plasma and bulk milk, a simple, reliable and rapid blocking ELISA ("Ceditest") has been developed using two monoclonal antibodies ("WB112" and "WB103") directed to different highly conserved epitopes on the non-struct

  19. Application of the Filariasis CELISA Antifilarial IgG Antibody Assay in Surveillance in Lymphatic Filariasis Elimination Programmes in the South Pacific

    Directory of Open Access Journals (Sweden)

    Hayley Joseph

    2011-01-01

    Full Text Available Elimination of lymphatic filariasis (LF in the Pacific Island Countries and Territories (PICT has been defined as <0.1% circulating filarial antigen (CFA prevalence in children born after the implementation of successful mass drug administrations (MDAs. This research assessed the feasibility of CFA and antibody testing in three countries; Tonga, Vanuatu, and Samoa. Transmission is interrupted in Vanuatu and Tonga as evidenced by no CFA positive children and a low antibody prevalence and titre. Transmission is ongoing in Samoa with microfilaraemic (Mf and CFA positive children and a high antibody prevalence and titre. Furthermore, areas of transmission were identified with Mf positive adults, but no CFA positive children. These areas had a high antibody prevalence in children. In conclusion, CFA testing in children alone was not useful for identifying areas of residual endemicity in Samoa. Thus, it would be beneficial to include antibody serology in the PICT surveillance strategy.

  20. Development and Validation of ELISA Assays for Determination of Serum Antibody against Pertussis Toxin, Filamentous Hemagglutinin, Pertactin of Bordetella Pertussis%百日咳毒素丝状血凝素和百日咳黏附素血清抗体检测方法的建立及验证

    Institute of Scientific and Technical Information of China (English)

    徐颖华; 骆鹏; 王丽婵; 卫辰; 侯启明; 张庶民

    2011-01-01

    . The limit of quantification of the assays had been demonstrated for anti-PT antibody with 1.31IU/ml, for anti-FHA antibody with 1.02IU/ml, for anti-Prn antibody with 0.51IU/ml. The average intra-assay coefficient of variation of three assays was 9.99%-. 11.01% and 9.00%. The average inter-assay coefficient of variation of three assays was 11.55% -. 12.76% and 11.18%, respectively. The average recovery rates of three assays were 97.19% ■. 101.20% and 107.83%, respectively. Three antibody levels in 30 serum sample were detected by ELISA methods developed in this study, which were not difference significantly in comparison with that of similar method from other country. These methods were also applied for immunogenicity analysis of three-component acellular pertussis vaccine in the clinical trial. Conclusion Three quantitative ELISA methods had been demonstrated to be simple, accurate and reproducible. They were used for evaluation of immunogenicy of acellular pertussis vaccine andinvestigation of pertussis epidemiology.

  1. Expression of Epstein-Barr virus antibodies EA-IgG, Rta-IgG, and VCA-IgA in nasopharyngeal carcinoma and their use in a combined diagnostic assay.

    Science.gov (United States)

    Li, Y; Wang, K; Yin, S K; Zheng, H L; Min, D L

    2016-03-18

    Epstein-Barr virus (EBV) infection is closely associated with nasopharyngeal carcinoma, which can be monitored by the levels of Rta protein antibody IgG (Rta-IgG), early antigen antibody (EA-IgG), and viral capsid antibody (VCA-IgA). In the present study, we investigated the serum levels of Rta-IgG, EA-IgG, and VCA-IgA in nasopharyngeal cancer patients, and the diagnostic value of a combined assay that includes these antibodies in addition to the EBV-DNA. A total of 56 nasopharyngeal cancer patients were recruited as the study population, along with 48 benign rhinitis patients and 42 healthy individuals. Serum EA-IgG, Rta-IgG, and VCA-IgA levels were measured by enzyme-linked immunosorbent assay, and EBV-DNA was quantified with PCR. The diagnostic value of these indices was further evaluated by ROC curve analysis. The expression levels of EA-IgG, Rta-IgG, VCA-IgA, and EBV-DNA were elevated in the nasopharyngeal cancer patients, who had higher levels of these antibodies than those in the rhinitis patients, followed by the healthy individuals. These indices were also increased with advanced TNM stage. The overall diagnostic efficacy was ranked as follows: VCA-IgA, Rta-IgA, EA-IgA, and EBV-DNA. The combined diagnosis using these four indices increased the sensitivity to 98.21% and the negative predictive value to 98.61%, without any significant compromise on the test specificity. In conclusion, EA-IgG, Rta-IgG, VCA-IgA, and EBV-DNA expression levels were elevated in nasopharyngeal patients. The combined diagnostic value of these serum indices has important implications in nasopharyngeal carcinoma.

  2. Characterization of degradation process of sucrase-isomaltase in rat jejunum with monoclonal-antibody-based enzyme-linked immunosorbent assay

    National Research Council Canada - National Science Library

    Goda, T; Quaroni, A; Koldovský, O

    1988-01-01

    ...]. To characterize further the process of sucrase-isomaltase degradation in jejunum, we determined the amounts of immunoreactive sucrase-isomaltase in rat jejunum by using a monoclonal-antibody-based...

  3. Production of a highly group-specific monoclonal antibody against zearalenone and its application in an enzyme-linked immunosorbent assay

    Science.gov (United States)

    Cha, Sang-Ho; Kim, Sung-Hee; Bischoff, Karyn; Kim, Hyun-Jeong; Son, Seong-Wan

    2012-01-01

    A monoclonal antibody (mAb) against zearalenone (ZEN) was produced using ZEN-carboxymethoxylamine and -BSA conjugates. Antibody produced by one clone showing a very high binding ability was selected and found to have a higher affinity for ZEN compared to a commerciall ZEN antibody. We developed two direct competitive ELISA systems using the selected antibody (ZEN-coated and anti-ZEN antibody-coated ELISA). Quantitative ranges for the anti-ZEN antibody-coated ELISA and ZEN-coated ELISA were from 25 to 750 ppb and from 12.5 to 100 ppb, respectively. The detection limit of both methods as measured with standard solutions was 10 ppb. The intra-plate and inter-well variation of both ELISAs were less than 10%. The IC50 values for α-zearalenol, β-zearalenol, α-zearalanol, and β-zearalanol compared to ZEN were 108.1, 119.3, 114.1, and 130.3% for the ZEN-coated ELISA. These values were 100.7, 120.7, 121.6, and 151.6% for the anti-ZEN antibody-coated ELISA. According to the anti-ZEN antibody-coated ELISA, the average recovery rates of ZEN from spiked animal feed containing 150 to 600 ng/mL of ZEN ranged from 106.07 to 123.00% with 0.93 to 2.28% coefficients of variation. Our results demonstrate that the mAb developed in this study could be used to simultaneously screen for ZEN and its metabolites in feed. PMID:22705733

  4. Evaluation of the 2. generation radio-receptional assay for anti-TSH receptor antibodies (TRAb) in autoimmune thyroid diseases. Comparison with 1. generation and anti-thyroperoxidae antibodies (AbTPO)

    Energy Technology Data Exchange (ETDEWEB)

    Giovanella, L.; Ceriani, L.; Garacini, S. [University Hospital Ospedale di Circolo e Fondazione Macchi, Dept. of Nuclear Medicine, Lab. of Endocrinology and Thyroid Unit, Varese (Italy)

    2001-03-01

    The detection of autoantibodies to the TSH-receptor (TRAb) by radio-receptor assays (RRA) is widely requested in clinical practice for the diagnostic work-up of Graves' disease and its differentiation from diffuse thyroid autonomy. Additionally, TRAb measurement can be useful during antithyroid drug treatment of Graves' disease to evaluate the risk of relapse after therapy discontinuation. Nevertheless, some patients affected by Graves' disease are TRAb-negative when 1. generation assay is used. In this study the diagnostic performance of a newly developed 2. generation TRAb assay (TRAK human DYNOtest(R), BRAHMS Diagnostica GmbH, Berlin, Germany) was evaluated in 74 untreated patients affected by Graves' disease, in 53 untreated patients affected by Hashimoto's thyroiditis and in 88 patients affected by euthyroid nodular goiter. It was also compared the new TRAb assay with the 1. generation test (TRAK(R) Assay, BRAHMS Diagnostica GmbH, Berlin, Germany) and anti-thyroperoxidase assay (AbTPO DYNOtest(R), BRAHMS GmbH, Berlin). The 2. generation TRAb assay showed the better diagnostic sensitivity in Graves' disease (97%) with respect to the 1. generation assay (85%) and AbTPO assay (64%). The AbTPO assay was positive in 50 of 53 (94%) patients affected by autoimmune thyroiditis. The 1. and 2. generation TRAb assays were positive in 4 (7%) and 7 (13%) of 53 patients affected by autoimmune thyroiditis, respectively. No patients affected by nodular goiter showed positive 1. and 2. generation TRAb assay while AbTPO levels were positive in 8 of 88 patients (specificity 91%). In conclusion, the 2. generation TRAb assay is clearly more sensitive than the 1. generation test and should be used in clinical practice to minimize the incidence of TRAb-negative Graves' disease. Long term prospective studies are needed to evaluate the prognostic role of 2. generation TRAb assay in Graves' disease. The assay of AbTPO is the best marker for

  5. Characteristics of enzyme-linked immunosorbent assay for detection of IgG antibodies specific to Сhlamydia trachomatis heat shock protein (HSP-60

    Directory of Open Access Journals (Sweden)

    O. Yu. Galkin

    2017-02-01

    Full Text Available The goal of this work was to study sensitivity and specificity of the developed ELISA set for the identification of IgG antibodies against Chlamydia trachomatis HSP-60 (using biotinylated tyramine-based signal amplification system. The study was conducted using a panel of characterized sera, as well as two reference ELISA sets of similar purpose. According to the results of ELISA informative value parameters, the ELISA we have developed showed the highest specificity and sensitivity parameters (no false negative or false positive results were registered. In 4 out of 15 intralaboratory panel serum samples initially identified as negative, anti-HSP-60 IgG-antibodies test result in reference ELISA sets upon dilution changed from negative to positive. The nature of titration curves of false negative sera and commercial monoclonal antibodies А57-В9 against C. trachomatis HSP-60 after incubation for 24 h was indicative of the presence of anti-idiotypic antibodies in these samples. Upon sera dilution, idiotypic-anti-idiotypic complexes dissociated, which caused the change of test result. High informative value of the developed ELISA set for identification of IgG antibodies against C. trachomatis HSP-60 has been proven. Anti-idiotypic antibodies possessing C. trachomatis anti-HSP-60 activity and being one of the causes of false negative results of the relevant ELISA-based tests have been identified in blood sera of individuals infected with chlamydial genitourinary infection agents.

  6. Development and application of a blocking enzyme-linked immunosorbent assay (ELISA) to differentiate antibodies against live and inactivated porcine reproductive and respiratory syndrome virus.

    Science.gov (United States)

    Cong, Yanlong; Huang, Zhiqiang; Sun, Yixue; Ran, Wei; Zhu, Lisai; Yang, Guilian; Ding, Xuemei; Yang, Zhanqing; Huang, Xiao; Wang, Chunfeng; Ding, Zhuang

    2013-09-01

    The aim of this study was to establish a method that could differentiate antibodies against live and inactivated vaccines of porcine reproductive and respiratory syndrome virus (PRRSV). A blocking ELISA (b-ELISA) was established using the PRRSV non-structural protein, Nsp9, as the antigen and a monoclonal antibody, 2D6, against the Nsp9 protein as the capture antibody. The test was validated by using 415 clinical sera in the b-ELISA compared to a commercial kit based on the indirect ELISA using the nucleocapsid (N) protein as antigen. Significant differences were observed for the data obtained by the two detection methods. This may be due to the commercial kit detecting antibodies elicited by live and inactivated virus, whereas the b-ELISA only detects antibodies produced by any active viral replication, such as natural infection or live vaccination. Therefore, the b-ELISA in this study is able to distinguish between antibodies against live and inactivated viruses in pigs.

  7. Stability evaluation of CNBr-Sepharose 4 B for using as solid matrix in immunoradiometric assay antibodies coupling; Avaliacao da estabilidade da CNBr-sepharose 4B para emprego como matriz solida no acoplamento de anticorpos especificos de ensaios imunorradiometricos

    Energy Technology Data Exchange (ETDEWEB)

    Haber, Esther Piltcher; Silva, Sandra Rosa da; Borghi, Vania Caira [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil); Wajchenberg, Bernardo Leo [Sao Paulo Univ., SP (Brazil). Faculdade de Medicina

    1995-12-31

    The present work verifies the stability of a CNBr-Sepharose 4 B product (Pharmacia) stored at our laboratory one year after its expire date in view of its application as solid phase antibodies in the development of an immunoradiometric assay for measurement of serum human proinsulin. From rabbit IgG antiserum previously purified and concentrated by ultrafiltration (Publication IPEN 294, 1990) the antibodies were isolated by affinity chromatography. Sheep antiserum anti-rabbit IgG were coupled to cyanogen bromide activated Sepharose 4 B and the rabbit IgG which were bound to the immunosorbent could be obtained by elution with stepwise pH gradient from pH 7.0 to pH 2.5. The complying efficiency of the sheep antiserum to this solid phase material was 97%. The elution profile obtained shows identify of the sample related to the antiserum anti-rabbit IgG by affinity chromatography. These results suggest that this CNBr-Sepharose 4 B lot can be used satisfactorily to attach antibodies for use in the two-site immunoradiometric assay. (author). 7 refs., 1 fig.

  8. [[Virus-like particle-based immunoglobulin M capture enzyme-linked immunosorbent assay for the detection of IgM antibodies against Chikungunya virus].

    Science.gov (United States)

    Li, Jian-dong; Zhang, Quan-fu; Zhang, Shuo; Li, Chuan; Liu, Qin-zhi; Liang, Mi-fang; Li, De-xin

    2014-11-01

    To establish a MacELISA method for the detection of IgM antibodies against Chikungunya virus (CHIKV), we prepared virus like particle (VLP) antigens of CHIKV using the whole structural protein C-E3-E2-6K-E1 encoding gene with a baculovirus expression system in Sf9 insect cells. The VLPs were purified and used to immunize Kunming mice. Then, polyclonal antibodies were purified from the samples of ascites with a protein G HiTrap SP column and labeled with horseradish peroxidase. A MacELISA method for the detection of IgM antibodies against CHIKV was assembled with goat anti-human IgM antibody, VLP antigens and an enzyme-labeled polyclonal antibody. The results were evaluated with a serum panel containing serum samples from laboratory-confirmed CHIK, HFRS patients, healthy donors, and commercially available CHIKV IgM as a quality control. It was shown that the MacELISA had a specificity of 99% (99/100), the coefficients of variation (CoV) within a plate were ELISA plates in terms of the plate variation coefficient was <15%. A comparative analysis was performed to compare the current method against a commercial CHIKV IgM antibody detection kit for IIFA-IgM. The detection limit of MacELISA was significantly lower than that of the IIFA-IgM commercial kit (P< 0.0001). Here, we demonstrate that the VLP-based MacELISA is a promising tool for the early diagnosis and epidemiological investigation of CHIKV infection, with a high level of sensitivity and specificity for the detection of IgM antibodies against CHIKV.

  9. Sensitivity and specificity enhanced enzyme-linked immunosorbent assay by rational hapten modification and heterogeneous antibody/coating antigen combinations for the detection of melamine in milk, milk powder and feed samples.

    Science.gov (United States)

    Cao, Biyun; Yang, Hong; Song, Juan; Chang, Huafang; Li, Shuqun; Deng, Anping

    2013-11-15

    The adulteration of food products with melamine has led to an urgent requirement for sensitive, specific, rapid and reliable quantitative/screening methods. To enhance the sensitivity and specificity of the enzyme-linked immunosorbent assay (ELISA) for the detection of melamine in milk, milk powder and feed samples, rational hapten modification and heterogeneous antibody/coating antigen combinations were adopted. Three melamine derivatives with different length of carboxylic spacer at the end were synthesized and linked to carrier proteins for the production of immunogens and coating antigens. Monoclonal antibody against melamine was produced by hybridoma technology. Under optimal experimental conditions, the standard curves of the ELISAs for melamine were constructed in range of 0.1-100 ng mL(-1). The sensitivity was 10-300 times enhanced compared to those in the published literatures. The cross-reactivity values of the ELISAs also demonstrated the assays exhibited high specificity. Five samples were spiked with melamine at different concentrations and detected by the ELISA. The recovery rates of 72.8-123.0% and intra-assay coefficients of variation of 0.8-18.9% (n=3) were obtained. The ELISA for milk sample was confirmed by high-performance liquid chromatography with a high correlation coefficient of 0.9902 (n=6). The proposed ELISA was proven to be a feasible quantitative/screening method for melamine analysis.

  10. Development and validation of cell-based luciferase reporter gene assays for measuring neutralizing anti-drug antibodies against interferon beta

    DEFF Research Database (Denmark)

    Hermanrud, Christina; Ryner, Malin; Luft, Thomas

    2016-01-01

    . The assays were re-developed and validated as part of the "Anti-Biopharmaceutical Immunization: Prediction and analysis of clinical relevance to minimize the risk" (ABIRISK) consortium and involved a joint collaboration between four academic laboratories and two pharmaceutical companies. The LUC assay...

  11. An ultra-sensitive monoclonal antibody-based fluorescent microsphere immunochromatographic test strip assay for detecting aflatoxin M1 in milk

    Science.gov (United States)

    A rapid lateral flow fluorescent microspheres immunochromatography test strip (FMs-ICTS) has been developed for the detection of aflatoxin M1 (AFM1) residues in milk. For this purpose, an ultra-sensitive anti-AFM1 monoclonal antibody (MAb) 1D3 was prepared and identified. The IC50 value of the MA...

  12. Localization and distribution of ‘Candidatus Liberibacter asiaticus’ in citrus and periwinkle by direct tissue blot immuno assay with an anti-OmpA polyclonal antibody

    Science.gov (United States)

    ‘Candidatus Liberibacter asiaticus’ (CaLas), a non-cultured member of the a-proteobacteria, is the causal agent of citrus Huanglongbing (HLB). Due to the difficulties of in vitro culture, antibodies against CaLas have not been widely used in studies of this pathogen. We have used an anti-OmpA poly...

  13. Evaluation of a Novel Enzyme-Linked Immunosorbent Assay To Detect Immunoglobulin G Antibody to Enolase for Serodiagnosis of Invasive Candidiasis▿

    Science.gov (United States)

    Laín, Ana; Moragues, María D.; Ruiz, Juan Carlos García; Mendoza, Joaquín; Camacho, Ana; del Palacio, Amalia; Pontón, José

    2007-01-01

    The performance of a new test to detect antibodies to Candida albicans recombinant enolase was investigated in 47 immunocompromised and 51 immunocompetent patients. The sensitivity, specificity, and positive and negative predictive values of the test for the diagnosis of invasive candidiasis were 81.0, 83.9, 79.1, and 85.5%, respectively. PMID:17229884

  14. Diagnostic performance of an indirect enzyme-linked immunosorbent assay (ELISA) to detect bovine leukemia virus antibodies in bulk-tank milk samples.

    Science.gov (United States)

    Nekouei, Omid; Durocher, Jean; Keefe, Greg

    2016-07-01

    This study assessed the diagnostic performance of a commercial ELISA for detecting bovine leukemia virus antibodies in bulk-tank milk samples from eastern Canada. Sensitivity and specificity of the test were estimated at 97.2% and 100%, respectively. The test was recommended as a cost-efficient tool for large-scale screening programs.

  15. Synthesis of an oxytetracyline-tolidin-BSA immunogen and antibodies production of anti-oxytetracyline developed for oxytetracyline residue detection with enzyme-linked immunosorbent assays technique

    Directory of Open Access Journals (Sweden)

    Widiastuti R

    2013-06-01

    Full Text Available An oxytetracycline-tolidin-bovine serum albumin (OTC-tolidin-BSA-conjugate was synthezed as immunogen for producing specific antibodies in immunized rabbits that would be used as reagent for development of OTC residue detection with enzym-linked immunoassays technique. The immunogen was prepared through diazotization tolidin and subsequently reacted with OTC. The red purple immunogen of OTC-tolidin-BSA absorbed at wave lengths of 277 nm and 488 nm under UV screening absorbances and confirmation with the high performance liquid chromatography (HPLC showed the absence of peak at retention time of 3.46 minutes. Characaterized result with SDS-PAGE showed the molecular weight of the OTC-tolidin-BSA at 69.79 kDA. Subsequently, the immunogen was immunized into New Zealand rabbits in order to produce the polyclonal antibodies. The antibodies were purified using a protein A sepharose column. The OD optimum responses of 0.92 to 1.20 were obtained from the second fractionation at dilution of 1/1000 by titrating the antibodies and OTC-tolidin-BSA coating antigen at concentration of 10 µg/mL on several bleeding times.

  16. ALS试验(TB-S A抗体)在结核性胸膜炎辅助诊断中的应用%Evaluation of ALS assay (TB-SA antibody)in diagnosis of tuberculous pleurisy

    Institute of Scientific and Technical Information of China (English)

    焦瑾; 王茂水; 吴艳华; 王新锋

    2014-01-01

    Objective To investigate the diagnostic value of the ALS assay (TB-SA antibody)in the tuberculous pleu-risy.Methods 55 patients diagnosed as tuberculous pleurisy (TPE group)and 45 healthy persons (healthy group) were enrolled.The levels of TB-SA antibody from lymphocyte secretion were detected by ELISA assay.Mann-Whitney U test was used to compare the levels of TB-SA antibody between the two groups.Receiver operating characteristic (ROC)analysis was performed to analyze the sensitivity of ALS assay (TB-SA antibody)in diagnosis of tuberculous pleurisy.Results The mean concetration of TB-SA antibody from lymphocyte secretion in TPE group was significantly higher than that in healthy group (P<0.01).The area under the curve,best cutoff point,sensitivity,specificity,posi-tive likehood ratio and negtive likehood ratio of the ALS assay (TB-SA)were 0.900 (95%CI:0.824-0.95 1 ),0.04, 77.8%,92.7%,10.69 and 0.24,respectively.Conclusion ALS (TB-SA antibody)assay performs well in the di-agnosis of tuberculous pleurisy.%目的:探讨ALS试验(TB-SA抗体)在结核性胸膜炎辅助诊断中的应用价值。方法选取初治结核性胸膜炎患者(结核组)55例和健康体检者(对照组)45例,采用ELISA法测定淋巴细胞分泌液中结核抗体的含量。采用Mann-Whitney U检验比较两组之间 TB-SA 抗体的差异,绘制受试者工作特征(ROC )曲线评价 ALS 试验(TB-SA抗体)对结核性胸膜炎诊断的敏感性。结果结核组TB-SA抗体的浓度显著高于正常组(P<0.01)。根据两组数据绘制受试者工作特征曲线(ROC曲线),曲线下面积为0.900(95%CI:0.824~0.951),截断点为0.04,敏感性和特异性分别为77.8%和92.7%,阳性似然比和阴性似然比分别为10.69和0.24。结论 ALS(TB-SA抗体)试验在结核性胸膜炎的诊断中具有一定的价值。

  17. Evaluation of a commercial competitive enzyme-linked immunosorbent assay for detection of avian influenza virus subtype H5 antibodies in zoo birds

    DEFF Research Database (Denmark)

    Jensen, Trine Hammer; Andersen, Jannie Holmegaard; Hjulsager, Charlotte Kristiane

    2017-01-01

    compared a commercial ELISA for detection of AIV subtype H5 antibodies with HI test of 572 serum samples from zoo birds. There was no significant difference between the results of the two tests when statistically compared by a McNemar χ2 test (P = 0.86) and assessment of κ (κ = 0.87). With a specificity...... of 94.2% (95% confidence interval [CI], 0.92-0.97), a sensitivity of 93.9% (95% CI, 0.91-0.97), and an excellent correlation between the two tests, this ELISA can be recommended as an alternative to the HI test for preliminary screening of zoo bird sera for antibodies to AIV subtype H5....

  18. Impact of de novo donor-specific HLA antibodies detected by Luminex solid-phase assay after transplantation in a group of 88 consecutive living-donor renal transplantations.

    Science.gov (United States)

    Dieplinger, Georg; Ditt, Vanessa; Arns, Wolfgang; Huppertz, Andrea; Kisner, Tuelay; Hellmich, Martin; Bauerfeind, Ursula; Stippel, Dirk L

    2014-01-01

    De novo donor-specific HLA antibodies (DSA) after renal transplantation are known to be correlated with poor graft outcome and the development of acute and chronic rejection. Currently, data for the influence of de novo DSA in patient cohorts including only living-donor renal transplantations (LDRT) are limited. A consecutive cohort of 88 LDRT was tested for the occurrence of de novo DSA by utilizing the highly sensitive Luminex solid-phase assay for antibody detection. Data were analyzed for risk factors for de novo DSA development and correlated with acute rejection (AR) and graft function. Patients with de novo DSA [31 (35%)] showed a trend for inferior graft function [mean creatinine change (mg/dL/year) after the first year: 0.15 DSA (+) vs. 0.02 DSA (-) (P = 0.10)] and a higher rate of AR episodes, especially in case of de novo DSA of both class I and II [6 (55%), (P = 0.05)]. Antibody-mediated rejection (AMR) appeared in five patients and was significantly correlated with de novo DSA (P = 0.05). Monitoring for de novo DSA after LDRT may help to identify patients at risk of declining renal function. Especially patients with simultaneous presence of de novo DSA class I and class II are at a high risk to suffer AR episodes.

  19. Clinical Evaluation of BioPlex 2200 HIV Ag-Ab, an Automated Screening Method Providing Discrete Detection of HIV-1 p24 Antigen, HIV-1 Antibody, and HIV-2 Antibody

    OpenAIRE

    Salmona, Maud; Delarue, Severine; Delaugerre, Constance; Simon, François; Maylin, Sarah

    2014-01-01

    Early and accurate diagnosis is essential for optimal therapeutic outcomes in patients infected with HIV. Currently, none of the commercially available fourth-generation assays differentiate HIV-1 and HIV-2 antibodies (Ab) or the HIV-1 p24 antigen (Ag). The aim of this study was to evaluate the performance of a novel assay, the BioPlex 2200 HIV Ag-Ab. This assay uses a multiplex flow immunoassay design allowing the simultaneous detection and identification of antibodies to HIV-1 (groups M and...

  20. Pseudotype-based neutralization assays for influenza: a systematic analysis

    Directory of Open Access Journals (Sweden)

    George William Carnell

    2015-04-01

    Full Text Available The use of vaccination against the influenza virus remains the most effective method of mitigating the significant morbidity and mortality caused by this virus. Antibodies elicited by currently licensed influenza vaccines are predominantly hemagglutination-inhibition (HI-competent antibodies that target the globular head of HA thus inhibiting influenza virus entry into target cells. These antibodies predominantly confer homosubtypic/strain specific protection and only rarely confer heterosubtypic protection. However, recent academia or pharma-led R&D towards the production of a universal vaccine has centered on the elicitation of antibodies directed against the stalk of the influenza HA that has been shown to confer broad protection across a range of different subtypes (H1 to H16. The accurate and sensitive measurement of antibody responses elicited by these next-generation influenza vaccines is however hampered by the lack of sensitivity of the traditional influenza serological assays hemagglutinin inhibition (HI, single radial hemolysis (SRH and microneutralization (MN. Assays utilizing pseudotypes, chimeric viruses bearing influenza glycoproteins, have been shown to be highly efficient for the measurement of homosubtypic and heterosubtypic broadly-neutralizing antibodies, making them ideal serological tools for the study of cross-protective responses against multiple influenza subtypes with pandemic potential. In this review, we will analyze and compare literature involving the production of influenza pseudotypes with particular emphasis on their use in serum antibody neutralization assays. This will enable us to establish the parameters required for optimization and propose a consensus protocol to be employed for the further deployment of these assays in influenza vaccine immunogenicity studies.

  1. [Comparison of antibody responses to hepatitis B surface antigen among four recipient groups of hepatitis B vaccines that have been approved in Japan: evaluation using passive hemagglutination assay and chemiluminescent immunoassay].

    Science.gov (United States)

    Ogata, Norio

    2009-10-01

    In hepatitis B virus (HBV) infection-preventing programs, serum or plasma levels of antibody to hepatitis B surface antigen (anti-HBs) are important to determine whether individuals are protective or not. We compared anti-HBs responses using passive hemagglutination assay (Mycell) and chemiluminescent immunoassay (Architect) among four recipient groups of HB vaccines, Meinyu, HBY, Bimmugen and Heptavax II, that have been approved in Japan. Overall, in a total of 1875 vaccinees Mycell results showed recipient groups of Meinyu and HBY acquired higher anti-HBs levels than those of Bimmugen and Heptavax II. Comparison of anti-HBs responses by both Mycell and Architect in recipient groups of Meinyu (n=150), HBY (n=218), Bimmugen (n=260), and Heptavax II (n=47) demonstrated the order of vaccinees' responses, such as geometric mean titers, ratios of acquiring high antibody levels (Mycell titers over 1024, Architect measurements over 1000 mIU/mL), and ratios of having unsuccessful antibody responses (Mycell titers under 8, Architect measurements under 10 mIU/mL), were somewhat different between the two assays. Comparison of Architect measurements at given Mycell titers revealed Bimmugen-recipients showed significantly lower values than HBY- or Heptavax II-recipients. Around critical protective levels, 5 of 22 Bimmugen-recipients with Mycell titers 16 or 32 showed Architect measurements under 10 mIU/mL, while 8 of 11 Heptavax II-recipients with Mycell titers below 8 demonstrated Architect measurements over 10 mIU/mL. Thus, discrepancies in anti-HBs evaluation between Mycell and Architect seemed to partly depend on administered vaccines. These results indicate anti-HBs concentration should be evaluated carefully so that we could completely prevent HBV infection.

  2. Accurate quantitation for in vitro refolding of single domain antibody fragments expressed as inclusion bodies by referring the concomitant expression of a soluble form in the periplasms of Escherichia coli.

    Science.gov (United States)

    Noguchi, Tomoaki; Nishida, Yuichi; Takizawa, Keiji; Cui, Yue; Tsutsumi, Koki; Hamada, Takashi; Nishi, Yoshisuke

    2017-03-01

    Single domain antibody fragments from two species, a camel VHH (PM1) and a shark VNAR (A6), were derived from inclusion bodies of E. coli and refolded in vitro following three refolding recipes for comparing refolding efficiencies: three-step cold dialysis refolding (TCDR), one-step hot dialysis refolding (OHDR), and one-step cold dialysis refolding (OCDR), as these fragments were expressed as 'a soluble form' either in cytoplasm or periplasm, but the amount were much less than those expressed as 'an insoluble form (inclusion body)' in cytoplasm and periplasm. In order to verify the refolding efficiencies from inclusion bodies correctly, proteins purified from periplasmic soluble fractions were used as reference samples. These samples showed far-UV spectra of a typical β-sheet-dominant structure in circular dichroism (CD) spectroscopy and so did the refolded samples as well. As the maximal magnitude of ellipticity in millidegrees (θmax) observed at a given wave length was proportional to the concentrations of the respective reference samples, we could draw linear regression lines for the magnitudes vs. sample concentrations. By using these lines, we measured the concentrations for the refolded PM1 and A6 samples purified from solubilized cytoplasmic insoluble fractions. The refolding efficiency of PM1 was almost 50% following TCDR and 40% and 30% following OHDR and OCDR, respectively, whereas the value of A6 was around 30% following TCDR, and out of bound for quantitation following the other two recipes. The ELISA curves, which were derived from the refolded samples, coincided better with those obtained from the reference samples after converting the values from the protein-concentrations at recovery to the ones of refolded proteins using recovery ratios, indicating that such a correction gives better results for the accurate measure of the ELISA curves than those without correction. Our method require constructing a dual expression system, expressed both in

  3. Generation of monoclonal antibodies against peptidylarginine deiminase 2 (PAD2) and development of a PAD2-specific enzyme-linked immunosorbent assay

    DEFF Research Database (Denmark)

    Damgaard, Dres; Palarasah, Yaseelan; Skjødt, Karsten

    2014-01-01

    Abs) against rabbit PAD2 and evaluated their cross-reactivity with human PAD2 by indirect enzyme-linked immunosorbent assay (ELISA), western blotting and immunohistological staining of inflamed synovial tissue. Moreover, we established a sandwich ELISA detecting human PAD2, based on two different monoclonal...

  4. Enzyme-Linked Immunosorbent Assay To Differentiate the Antibody Responses of Animals Infected with Brucella Species from Those of Animals Infected with Yersinia enterocolitica O9

    OpenAIRE

    Erdenebaatar, Janchivdorj; Bayarsaikhan, Balgan; Watarai, Masahisa; Makino, Sou-ichi; Shirahata, Toshikazu

    2003-01-01

    Enzyme-linked immunosorbent assays using antigens extracted from Brucella abortus with n-lauroylsarcosine differentiated natural Brucella-infected animals from Brucella-vaccinated or Yersinia enterocolitica O9-infected animals. A field trial in Mongolia showed cattle, sheep, goat, reindeer, camel, and human sera without infection could be distinguished from Brucella-infected animals by conventional serological tests.

  5. Enzyme-linked immunosorbent assay to differentiate the antibody responses of animals infected with Brucella species from those of animals infected with Yersinia enterocolitica O9.

    Science.gov (United States)

    Erdenebaatar, Janchivdorj; Bayarsaikhan, Balgan; Watarai, Masahisa; Makino, Sou-ichi; Shirahata, Toshikazu

    2003-07-01

    Enzyme-linked immunosorbent assays using antigens extracted from Brucella abortus with n-lauroylsarcosine differentiated natural Brucella-infected animals from Brucella-vaccinated or Yersinia enterocolitica O9-infected animals. A field trial in Mongolia showed cattle, sheep, goat, reindeer, camel, and human sera without infection could be distinguished from Brucella-infected animals by conventional serological tests.

  6. A specific assay for quantification of human C4c by use of an anti-C4c monoclonal antibody