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Sample records for neutralizing antibody assays

  1. A safe and reliable neutralization assay based on pseudovirus to measure neutralizing antibody titer against poliovirus.

    Science.gov (United States)

    Liu, Shaohua; Song, Dongmei; Bai, Han; Lu, Weiwei; Dai, Xinxian; Hao, Chunsheng; Zhang, Zhongyang; Guo, Huijie; Zhang, Yue; Li, Xiuling

    2017-12-01

    With the promotion of inactivated poliomyelitis vaccine (IPV) and live attenuated oral poliomyelitis vaccine (OPV), the global reported cases of poliomyelitis have reduced sharply from 0.35 million in 1988 to 74 in 2015. The Polio Eradication & Endgame Strategic Plan published by WHO in 2013 included the strategy of implementation of poliovirus safe handling and containment measures to minimize the risks of facility-associated reintroduction of virus into the polio-free community to prevent the re-import of poliovirus. Toward this strategy, we produced replication-incompetent pseudovirus of poliovirus type 1, 2, 3 attenuated strains by constructing poliovirus capsid expression vectors and poliovirus replicon then transfecting HEK293T cells and developed a pseudovirus-based neutralization assay (pNA) to determine neutralizing antibody titer which is more secure, time-saving and reliable than conventional neutralization assay (cNA). By using anti-poliovirus rat serum, we demonstrated excellent correlation between neutralizing antibody titers measured by cNA and pNA. It was concluded that pNA can be a potential alternative to replace cNA as a safe and time-saving system for titer determination after live poliovirus's safekeeping. © 2017 Wiley Periodicals, Inc.

  2. A novel reporter system for neutralizing and enhancing antibody assay against dengue virus.

    Science.gov (United States)

    Song, Ke-Yu; Zhao, Hui; Jiang, Zhen-You; Li, Xiao-Feng; Deng, Yong-Qiang; Jiang, Tao; Zhu, Shun-Ya; Shi, Pei-Yong; Zhang, Bo; Zhang, Fu-Chun; Qin, E-De; Qin, Cheng-Feng

    2014-02-18

    Dengue virus (DENV) still poses a global public health threat, and no vaccine or antiviral therapy is currently available. Antibody plays distinct roles in controlling DENV infections. Neutralizing antibody is protective against DENV infection, whereas sub-neutralizing concentration of antibody can increase DENV infection, termed antibody-dependent enhancement (ADE). Plaque-based assay represents the most widely accepted method measuring neutralizing or enhancing antibodies. In this study, a novel reporter virus-based system was developed for measuring neutralization and ADE activity. A stable Renilla luciferase reporter DENV (Luc-DENV) that can produce robust luciferase signals in BHK-21 and K562 cells were used to establish the assay and validated against traditional plaque-based assay. Luciferase value analysis using various known DENV-specific monoclonal antibodies showed good repeatability and a well linear correlation with conventional plaque-based assays. The newly developed assay was finally validated with clinical samples from infected animals and individuals. This reporter virus-based assay for neutralizing and enhancing antibody evaluation is rapid, lower cost, and high throughput, and will be helpful for laboratory detection and epidemiological investigation for DENV antibodies.

  3. A novel, colorimetric neutralization assay for measuring antibodies to influenza viruses.

    Science.gov (United States)

    Lehtoranta, Liisa; Villberg, Anja; Santanen, Riitta; Ziegler, Thedi

    2009-08-01

    A colorimetric cell proliferation assay for measuring neutralizing antibodies to influenza viruses in human sera is described. Following a 90-min incubation, the serum-virus mixture was transferred to Madin-Darby canine kidney cells cultured in 96-well plates. After further incubation for three days, a tetrazolium salt was added to the wells. Cellular mitochondrial dehydrogenases cleave the tetrazolium salt to formazan, and the resulting color change is read by a spectrophotometer. The absorbance values correlate directly to the number of viable cells in the assay well and thus also to the neutralizing activity of influenza-specific antibodies present in the serum. With the few hands-on manipulations required, this assay allows simultaneous testing of a considerable number of sera, offers opportunities for automation, and is suitable for use under biosafety level-3 conditions. The test was used to study the antibody response after the administration of seasonal, inactivated, trivalent influenza vaccine. Antibody titers determined by the neutralization test in pre- and post-vaccination serum pairs were compared with those obtained by the hemagglutination inhibition assay. The neutralization test yielded higher pre- and post-vaccination titers and a larger number of significant increases in post-vaccination antibody titer than the hemagglutination inhibition test. This new test format could serve as a valuable laboratory tool for influenza vaccine studies.

  4. 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.

  5. Bluetongue virus: comparative evaluation of enzyme-linked immunosorbent assay, immunodiffusion, and serum neutralization for detection of viral antibodies.

    OpenAIRE

    Poli, G; Stott, J; Liu, Y S; Manning, J S

    1982-01-01

    Comparative studies on the detection of bovine serum immunoglobulin G antibodies to bluetongue virus with an enzyme-linked immunosorbent assay, an immunodiffusion method, and a serum neutralization assay demonstrated complete concordance between the enzyme-linked immunosorbent assay and the serum neutralization assay results. However, the immunodiffusion method failed to detect bluetongue virus antibody in a substantial number of sera found to possess bluetongue virus immunoglobulin G with th...

  6. 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.

  7. 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

    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...... 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...

  8. Optimization and validation of a neutralizing antibody assay for HIV-1 in A3R5 cells.

    Science.gov (United States)

    Sarzotti-Kelsoe, Marcella; Daniell, Xiaoju; Todd, Christopher A; Bilska, Miroslawa; Martelli, Amanda; LaBranche, Celia; Perez, Lautaro G; Ochsenbauer, Christina; Kappes, John C; Rountree, Wes; Denny, Thomas N; Montefiori, David C

    2014-07-01

    A3R5 is a human CD4(+) lymphoblastoid cell line that was engineered to express CCR5 and is useful for the detection of weak neutralizing antibody responses against tier 2 strains of HIV-1. Here we describe the optimization and validation of the HIV-1 neutralizing antibody assay that utilizes A3R5 cells, performed in compliance with Good Clinical Laboratory Practice (GCLP) guidelines. The assay utilizes Renilla luciferase-expressing replication competent infectious molecular clones (IMC) encoding heterologous env genes from different HIV-1 clades. Key assay validation parameters tested included specificity, accuracy, precision, limit of detection and quantitation, specificity, linearity and range, and robustness. Plasma samples demonstrated higher non-specific activity than serum samples in the A3R5 assay. This assay can tolerate a wide range of virus input but is more sensitive to cell concentration. The higher sensitivity of the A3R5 assay in neutralization responses to tier 2 strains of HIV-1 makes it complementary to, but not a substitute for the TZM-bl assay. The validated A3R5 assay is employed as an endpoint immunogenicity test for vaccine-elicited neutralizing antibodies against tier 2 strains of HIV-1, and to identify correlates of protection in HIV-1 vaccine trials conducted globally. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    International Nuclear Information System (INIS)

    Hovi, T.; Roivainen, M.

    1989-01-01

    We have developed a new rapid test, the radiometric cytolysis inhibition assay (RACINA), for the determination of neutralizing poliovirus antibodies. HeLa cells prelabeled with 51 Cr, [ 3 H]leucine, or, preferentially, with [ 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

  10. A rapid and quantitative assay for measuring antibody-mediated neutralization of West Nile virus infection

    International Nuclear Information System (INIS)

    Pierson, Theodore C.; Sanchez, Melissa D.; Puffer, Bridget A.; Ahmed, Asim A.; Geiss, Brian J.; Valentine, Laura E.; Altamura, Louis A.; Diamond, Michael S.; Doms, Robert W.

    2006-01-01

    West Nile virus (WNV) is a neurotropic flavivirus within the Japanese encephalitis antigenic complex that is responsible for causing West Nile encephalitis in humans. The surface of WNV virions is covered by a highly ordered icosahedral array of envelope proteins that is responsible for mediating attachment and fusion with target cells. These envelope proteins are also primary targets for the generation of neutralizing antibodies in vivo. In this study, we describe a novel approach for measuring antibody-mediated neutralization of WNV infection using virus-like particles that measure infection as a function of reporter gene expression. These reporter virus particles (RVPs) are produced by complementation of a sub-genomic replicon with WNV structural proteins provided in trans using conventional DNA expression vectors. The precision and accuracy of this approach stem from an ability to measure the outcome of the interaction between antibody and viral antigens under conditions that satisfy the assumptions of the law of mass action as applied to virus neutralization. In addition to its quantitative strengths, this approach allows the production of WNV RVPs bearing the prM-E proteins of different WNV strains and mutants, offering considerable flexibility for the study of the humoral immune response to WNV in vitro. WNV RVPs are capable of only a single round of infection, can be used under BSL-2 conditions, and offer a rapid and quantitative approach for detecting virus entry and its inhibition by neutralizing antibody

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

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

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    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.

  13. Recent advances in the characterization of HIV-1 neutralization assays for standardized evaluation of the antibody response to infection and vaccination.

    Science.gov (United States)

    Polonis, Victoria R; Brown, Bruce K; Rosa Borges, Andrew; Zolla-Pazner, Susan; Dimitrov, Dimiter S; Zhang, Mei-Yun; Barnett, Susan W; Ruprecht, Ruth M; Scarlatti, Gabriella; Fenyö, Eva-Maria; Montefiori, David C; McCutchan, Francine E; Michael, Nelson L

    2008-06-05

    In AIDS vaccine development the pendulum has swung towards a renewed emphasis on the potential role for neutralizing antibodies in a successful global vaccine. It is recognized that vaccine-induced antibody performance, as assessed in the available neutralization assays, may well serve as a "gatekeeper" for HIV-1 subunit vaccine prioritization and advancement. As a result, development of a standardized platform for reproducible measurement of neutralizing antibodies has received considerable attention. Here we review current advancements in our knowledge of the performance of different types of antibodies in a traditional primary cell neutralization assay and the newer, more standardized TZM-bl reporter cell line assay. In light of recently revealed differences (see accompanying article) in the results obtained in these two neutralization formats, parallel evaluation with both platforms should be contemplated as an interim solution until a better understanding of immune correlates of protection is achieved.

  14. 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.

  15. Development and characterization of a pre-treatment procedure to eliminate human monoclonal antibody therapeutic drug and matrix interference in cell-based functional neutralizing antibody assays.

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    Xu, Weifeng; Jiang, Hao; Titsch, Craig; Haulenbeek, Jonathan R; Pillutla, Renuka C; Aubry, Anne-Françoise; DeSilva, Binodh S; Arnold, Mark E; Zeng, Jianing; Dodge, Robert W

    2015-01-01

    Biological therapeutics can induce an undesirable immune response resulting in the formation of anti-drug antibodies (ADA), including neutralizing antibodies (NAbs). Functional (usually cell-based) NAb assays are preferred to determine NAb presence in patient serum, but are often subject to interferences from numerous serum factors, such as growth factors and disease-related cytokines. Many functional cell-based NAb assays are essentially drug concentration assays that imply the presence of NAbs by the detection of small changes in functional drug concentration. Any drug contained in the test sample will increase the total amount of drug in the assay, thus reducing the sensitivity of NAb detection. Biotin-drug Extraction with Acid Dissociation (BEAD) has been successfully applied to extract ADA, thereby removing drug and other interfering factors from human serum samples. However, to date there has been no report to estimate the residual drug level after BEAD treatment when the drug itself is a human monoclonal antibody; mainly due to the limitation of traditional ligand-binding assays. Here we describe a universal BEAD optimization procedure for human monoclonal antibody (mAb) drugs by using a LC-MS/MS method to simultaneously measure drug (a mutant human IgG4), NAb positive control (a mouse IgG), and endogenous human IgGs as an indicator of nonspecific carry-over in the BEAD eluate. This is the first report demonstrating that residual human mAb drug level in clinical sample can be measured after BEAD pre-treatment, which is critical for further BEAD procedure optimization and downstream immunogenicity testing. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Comparison of two high-throughput assays for quantification of adenovirus type 5 neutralizing antibodies in a population of donors in China.

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    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

  17. 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

    a normal distribution for the majority of runs, allowing a parametric approach for cut-point calculation to be used, where NAb positive samples could be identified with 95% confidence. An analysis of means and variances indicated that a floating cut-point should be used for all assays. The assays......Neutralizing anti-drug antibodies (NAbs) against therapeutic interferon beta (IFNβ) in people with multiple sclerosis (MS) are measured with cell-based bioassays. The aim of this study was to redevelop and validate two luciferase reporter-gene bioassays, LUC and iLite, using a cut-point approach...... to identify NAb positive samples. Such an approach is favored by the pharmaceutical industry and governmental regulatory agencies as it has a clear statistical basis and overcomes the limitations of the current assays based on the Kawade principle. The work was conducted following the latest assay guidelines...

  18. Recommendations for the validation of cell-based assays used for the detection of neutralizing antibody immune responses elicited against biological therapeutics.

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    Gupta, Shalini; Devanarayan, Viswanath; Finco, Deborah; Gunn, George R; Kirshner, Susan; Richards, Susan; Rup, Bonita; Song, An; Subramanyam, Meena

    2011-07-15

    The administration of biological therapeutics may result in the development of anti-drug antibodies (ADAs) in treated subjects. In some cases, ADA responses may result in the loss of therapeutic efficacy due to the formation of neutralizing ADAs (NAbs). An important characteristic of anti-drug NAbs is their direct inhibitory effect on the pharmacological activity of the therapeutic. Neutralizing antibody responses are of particular concern for biologic products with an endogenous homolog whose activity can be potentially dampened or completely inhibited by the NAbs leading to an autoimmune-type deficiency syndrome. Therefore, it is important that ADAs are detected and characterized appropriately using sensitive and reliable methods. The design, development and optimization of cell-based assays used for detection of NAbs have been published previously by Gupta et al. 2007 [1]. This paper provides recommendations on best practices for the validation of cell-based NAb assay and suggested validation parameters based on the experience of the authors. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Development and validation of cell-based luciferase reporter gene assays for measuring neutralizing anti-drug antibodies against interferon beta.

    Science.gov (United States)

    Hermanrud, Christina; Ryner, Malin; Luft, Thomas; Jensen, Poul Erik; Ingenhoven, Kathleen; Rat, Dorothea; Deisenhammer, Florian; Sørensen, Per Soelberg; Pallardy, Marc; Sikkema, Dan; Bertotti, Elisa; Kramer, Daniel; Creeke, Paul; Fogdell-Hahn, Anna

    2016-03-01

    Neutralizing anti-drug antibodies (NAbs) against therapeutic interferon beta (IFNβ) in people with multiple sclerosis (MS) are measured with cell-based bioassays. The aim of this study was to redevelop and validate two luciferase reporter-gene bioassays, LUC and iLite, using a cut-point approach to identify NAb positive samples. Such an approach is favored by the pharmaceutical industry and governmental regulatory agencies as it has a clear statistical basis and overcomes the limitations of the current assays based on the Kawade principle. The work was conducted following the latest assay guidelines. 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 was validated at Innsbruck Medical University (LUCIMU) and at Rigshospitalet (LUCRH) Copenhagen, and the iLite assay at Karolinska Institutet, Stockholm. For both assays, the optimal serum sample concentration in relation to sensitivity and recovery was 2.5% (v/v) in assay media. A Shapiro-Wilk test indicated a normal distribution for the majority of runs, allowing a parametric approach for cut-point calculation to be used, where NAb positive samples could be identified with 95% confidence. An analysis of means and variances indicated that a floating cut-point should be used for all assays. The assays demonstrated acceptable sensitivity for being cell-based assays, with a confirmed limit of detection in neat serum of 1519 ng/mL for LUCIMU, 814 ng/mL for LUCRH, and 320 ng/mL for iLite. Use of the validated cut-point assay, in comparison with the previously used Kawade method, identified 14% more NAb positive samples. In conclusion, implementation of the cut-point design resulted in increased sensitivity to detect NAbs. However, the clinical significance of these low

  20. Comparison of cell-based and non-cell-based assay platforms for the detection of clinically relevant anti-drug neutralizing antibodies for immunogenicity assessment of therapeutic proteins.

    Science.gov (United States)

    Hu, Jenny; Wala, Iwona; Han, Hong; Nagatani, Janice; Barger, Troy; Civoli, Francesca; Kaliyaperumal, Arunan; Zhuang, Yao; Gupta, Shalini

    2015-04-01

    Anti-drug neutralizing antibodies (NAbs) formed due to unwanted immunogenicity of a therapeutic protein point towards a mature immune response. NAb detection is important in interpreting the therapeutic's efficacy and safety in vivo. In vitro cell-based NAb assays provide a physiological system for NAb detection, however are complex assays. Non-cell-based competitive ligand binding (CLB) approaches are also employed for NAb detection. Instead of cells, CLB assays use soluble receptor and conjugated reagents and are easier to perform, however have reduced physiological relevance. The aim of this study was to compare the performance of CLB assays to established cell-based assays to determine the former's ability to detect clinically relevant NAbs towards therapeutics that (i) acted as an agonist or (ii) acted as antagonists by binding to a target receptor. We performed a head-to-head comparison of the performance of cell-based and CLB NAb assays for erythropoietin (EPO) and two anti-receptor monoclonal antibodies (AMG-X and AMG 317). Clinically relevant NAb-positive samples identified previously by a cell-based assay were assessed in the corresponding CLB format(s). A panel of 12 engineered fully human anti-EPO monoclonal antibodies (MAbs) was tested in both EPO NAb assay formats. Our results showed that the CLB format was (i) capable of detecting human anti-EPO MAbs of differing neutralizing capabilities and affinities and (ii) provided similar results as the cell-based assay for detecting NAbs in patient samples. The cell-based and CLB assays also behaved comparably in detecting NAbs in clinical samples for AMG-X. In the case of anti-AMG 317 NAbs, the CLB format failed to detect NAbs in more than 50% of the tested samples. We conclude that assay sensitivity, drug tolerance and the selected assay matrix played an important role in the inability of AMG 317 CLB assays to detect clinically relevant NAbs. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Comparison of in-house biotin-avidin tetanus IgG enzyme-linked-immunosorbent assay (ELISA) with gold standard in vivo mouse neutralization test for the detection of low level antibodies.

    Science.gov (United States)

    Sonmez, Cemile; Coplu, Nilay; Gozalan, Aysegul; Akin, Lutfu; Esen, Berrin

    2017-06-01

    Detection of anti-tetanus antibody levels is necessary for both determination of the immune status of individuals and also for planning preventive measures. ELISA is the preferred test among in vitro tests however it can be affected by the cross reacting antibodies. A previously developed in-house ELISA test was found not reliable for the antibody levels ≤1.0IU/ml. A new method was developed to detect low antibody levels correctly. The aim of the present study was to compare the results of the newly developed in-house biotin-avidin tetanus IgG ELISA test with the in vivo mouse neutralization test, for the antibody levels ≤1.0IU/ml. A total of 54 serum samples with the antibody levels of three different levels, =0.01IU/ml, 0.01-0.1IU/ml, 0.1-1IU/ml, which were detected by in vivo mouse neutralization test were studied by the newly developed in-house biotin-avidin tetanus IgG ELISA test. Test was validated by using five different concentrations (0.01IU/ml, 0.06IU/ml, 0.2IU/ml, 0.5IU/ml, 1.0IU/ml). A statistically significant correlation (r 2 =0.9967 p=0,001) between in vivo mouse neutralization test and in-house biotin-avidin tetanus IgG ELISA test, was observed. For the tested concentrations intra-assay, inter-assay, accuracy, sensitivity, specificity and coefficients of variations were determined as ≤15%. In-house biotin-avidin tetanus IgG ELISA test can be an alternative method to in vivo mouse neutralization method for the detection of levels ≤1.0IU/ml. By using in-house biotin-avidin tetanus IgG ELISA test, individuals with non protective levels, will be reliably detected. Copyright © 2017. Published by Elsevier B.V.

  2. Assaying Cellular Viability Using the Neutral Red Uptake Assay.

    Science.gov (United States)

    Ates, Gamze; Vanhaecke, Tamara; Rogiers, Vera; Rodrigues, Robim M

    2017-01-01

    The neutral red uptake assay is a cell viability assay that allows in vitro quantification of xenobiotic-induced cytotoxicity. The assay relies on the ability of living cells to incorporate and bind neutral red, a weak cationic dye, in lysosomes. As such, cytotoxicity is expressed as a concentration-dependent reduction of the uptake of neutral red after exposure to the xenobiotic under investigation. The neutral red uptake assay is mainly used for hazard assessment in in vitro toxicology applications. This method has also been introduced in regulatory recommendations as part of 3T3-NRU-phototoxicity-assay, which was regulatory accepted in all EU member states in 2000 and in the OECD member states in 2004 as a test guideline (TG 432). The present protocol describes the neutral red uptake assay using the human hepatoma cell line HepG2, which is often employed as an alternative in vitro model for human hepatocytes. As an example, the cytotoxicity of acetaminophen and acetyl salicylic acid is assessed.

  3. Radioimmunoassay for detection of VP1 specific neutralizing antibodies of foot and mouse disease virus

    International Nuclear Information System (INIS)

    Patzer, E.J.; Jackson, M.L.; Moore, D.M.

    1985-01-01

    A solid-phase radioimmunoassay was developed for the detection of antibodies against a specific region of the VP1 protein of the A24 and O1 serotypes of foot and mouth disease virus. The antibody titers from the radioimmunoassay showed a positive correlation with neutralizing antibody titers determined by a mouse protection assay. The specificity of the assay resides in the peptide used as antigen. The assay is rapid, reproducible and does not require the use of whole virions. (orig.)

  4. Antibody neutralization of retargeted measles viruses

    Science.gov (United States)

    Lech, Patrycja J.; Pappoe, Roland; Nakamura, Takafumi; Tobin, Gregory J.; Nara, Peter L.; Russell, Stephen J.

    2014-01-01

    The measles virus (MV) vaccine lineage is a promising oncolytic but prior exposure to the measles vaccine or wild-type MV strains limits treatment utility due to the presence of anti-measles antibodies. MV entry can be redirected by displaying a polypeptide ligand on the Hemagglutinin (H) C-terminus. We hypothesized that retargeted MV would escape neutralization by monoclonal antibodies (mAbs) recognizing the H receptor-binding surface and be less susceptible to neutralization by human antisera. Using chimeric H proteins, with and without mutations that ablate MV receptor binding, we show that retargeted MVs escape mAbs that target the H receptor-binding surface by virtue of mutations that ablate infection via SLAM and CD46. However, C-terminally displayed domains do not mediate virus entry in the presence of human antibodies that bind to the underlying H domain. In conclusion, utility of retargeted oncolytic measles viruses does not extend to evasion of human serum neutralization. PMID:24725950

  5. Kinetics of Epstein-Barr Virus (EBV) Neutralizing and Virus-Specific Antibodies after Primary Infection with EBV

    Science.gov (United States)

    Bu, Wei; Hayes, Gregory M.; Liu, Hui; Gemmell, Lorraine; Schmeling, David O.; Radecki, Pierce; Aguilar, Fiona; Burbelo, Peter D.; Woo, Jennifer; Balfour, Henry H.

    2016-01-01

    Prospective studies of antibodies to multiple Epstein-Barr virus (EBV) proteins and EBV neutralizing antibodies in the same individuals before, during, and after primary EBV infection have not been reported. We studied antibody responses to EBV in college students who acquired primary EBV infection during prospective surveillance and correlated the kinetics of antibody response with the severity of disease. Neutralizing antibodies and enzyme-linked immunosorbent assay (ELISA) antibodies to gp350, the major target of neutralizing antibody, reached peak levels at medians of 179 and 333 days after the onset of symptoms of infectious mononucleosis, respectively. No clear correlation was found between the severity of the symptoms of infectious mononucleosis and the peak levels of antibody to individual viral proteins or to neutralizing antibody. In summary, we found that titers of neutralizing antibody and antibodies to multiple EBV proteins increase over many months after primary infection with EBV. PMID:26888186

  6. Dengue-Immune Humans Have Higher Levels of Complement-Independent Enhancing Antibody than Complement-Dependent Neutralizing Antibody.

    Science.gov (United States)

    Yamanaka, Atsushi; Konishi, Eiji

    2017-09-25

    Dengue is the most important arboviral disease worldwide. We previously reported that most inhabitants of dengue-endemic countries who are naturally immune to the disease have infection-enhancing antibodies whose in vitro activity does not decrease in the presence of complement (complement-independent enhancing antibodies, or CiEAb). Here, we compared levels of CiEAb and complement-dependent neutralizing antibodies (CdNAb) in dengue-immune humans. A typical antibody dose-response pattern obtained in our assay system to measure the balance between neutralizing and enhancing antibodies showed both neutralizing and enhancing activities depending on serum dilution factor. The addition of complement to the assay system increased the activity of neutralizing antibodies at lower dilutions, indicating the presence of CdNAb. In contrast, similar dose-response curves were obtained with and without complement at higher dilutions, indicating higher levels of CiEAb than CdNAb. For experimental support for the higher CiEAb levels, a cocktail of mouse monoclonal antibodies against dengue virus type 1 was prepared. The antibody dose-response curves obtained in this assay, with or without complement, were similar to those obtained with human serum samples when a high proportion of D1-V-3H12 (an antibody exhibiting only enhancing activity and thus a model for CiEAb) was used in the cocktail. This study revealed higher-level induction of CiEAb than CdNAb in humans naturally infected with dengue viruses.

  7. In-Cell Western Assays to Evaluate Hantaan Virus Replication as a Novel Approach to Screen Antiviral Molecules and Detect Neutralizing Antibody Titers

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    Hong-Wei Ma

    2017-06-01

    Full Text Available Hantaviruses encompass rodent-borne zoonotic pathogens that cause severe hemorrhagic fever disease with high mortality rates in humans. Detection of infectious virus titer lays a solid foundation for virology and immunology researches. Canonical methods to assess viral titers rely on visible cytopathic effects (CPE, but Hantaan virus (HTNV, the prototype hantavirus maintains a relatively sluggish life cycle and does not produce CPE in cell culture. Here, an in-cell Western (ICW assay was utilized to rapidly measure the expression of viral proteins in infected cells and to establish a novel approach to detect viral titers. Compared with classical approaches, the ICW assay is accurate and time- and cost-effective. Furthermore, the ICW assay provided a high-throughput platform to screen and identify antiviral molecules. Potential antiviral roles of several DExD/H box helicase family members were investigated using the ICW assay, and the results indicated that DDX21 and DDX60 reinforced IFN responses and exerted anti-hantaviral effects, whereas DDX50 probably promoted HTNV replication. Additionally, the ICW assay was also applied to assess NAb titers in patients and vaccine recipients. Patients with prompt production of NAbs tended to have favorable disease outcomes. Modest NAb titers were found in vaccinees, indicating that current vaccines still require improvements as they cannot prime host humoral immunity with high efficiency. Taken together, our results indicate that the use of the ICW assay to evaluate non-CPE Hantaan virus titer demonstrates a significant improvement over current infectivity approaches and a novel technique to screen antiviral molecules and detect NAb efficacies.

  8. Cross-reactivity and phospholipase A2 neutralization of anti-irradiated Bothrops jararaca venom antibodies

    International Nuclear Information System (INIS)

    Spencer, P.J.; Nascimento, N. do; Paula, R.A. de; Cardi, B.A.; Rogero, J.R.

    1995-01-01

    The detoxified Bothrops jararaca venom, immunized rabbits with the toxoid obtained and investigated cross-reactivity of the antibodies obtained against autologous and heterelogous venoms was presented. It was also investigated the ability of the IgGs, purified by affinity chromatography, from those sera to neutralize phospholipase. A 2 , an ubiquous enzyme in animal venoms. Results indicate that venom irradiation leads to an attenuation of toxicity of 84%. Cross-reactivity was investigated by ELISA and Western blot and all venoms were reactive to the antibodies. On what refers to phospholipase A 2 activity neutralization, the antibodies neutralized autologous venoms efficiently and, curiously, other venoms from the same genus were not neutralized, while Lachesis muta venom, a remote related specier, was neutralized by this serum. These data suggest that irradiation preserve important epitopes for induction of neutralizing antibodies and that these epitopes are not shared by all venoms assayed. (author). 8 refs, 2 figs, 3 tabs

  9. International Network for Comparison of HIV Neutralization Assays: The NeutNet Report

    NARCIS (Netherlands)

    Fenyö, Eva Maria; Heath, Alan; Dispinseri, Stefania; Holmes, Harvey; Lusso, Paolo; Zolla-Pazner, Susan; Donners, Helen; Heyndrickx, Leo; Alcami, Jose; Bongertz, Vera; Jassoy, Christian; Malnati, Mauro; Montefiori, David; Moog, Christiane; Morris, Lynn; Osmanov, Saladin; Polonis, Victoria; Sattentau, Quentin; Schuitemaker, Hanneke; Sutthent, Ruengpung; Wrin, Terri; Scarlatti, Gabriella

    2009-01-01

    BACKGROUND: Neutralizing antibody assessments play a central role in human immunodeficiency virus type-1 (HIV-1) vaccine development but it is unclear which assay, or combination of assays, will provide reliable measures of correlates of protection. To address this, an international collaboration

  10. Egg yolk antibodies for detection and neutralization of Clostridium botulinum type A neurotoxin.

    Science.gov (United States)

    Trott, D L; Yang, M; Gonzalez, J; Larson, A E; Tepp, W H; Johnson, E A; Cook, M E

    2009-05-01

    The objective of this research project was to determine the usefulness of an egg antibody platform for producing materials for the detection and neutralization of botulinum type A neurotoxin. Yield estimates for detection and neutralizing antibodies produced using methods described were calculated. Antibody specific to botulinum toxoid A (aToxoid) and toxin A (aBoNT/A) was produced by immunizing hens with botulinum toxoid A (toxoid) followed by increasing amounts of botulinum neurotoxin A (BoNT/A) in Freund incomplete adjuvant. Egg yolks were extracted with polyethylene glycol (PEG) for antibody detection and neutralization experiments. A model aToxoid/toxoid immunoassay using only egg yolk antibody was developed and had a detection limit of 1 pg/ml of toxoid. In an indirect enzyme-linked immunosorbent assay of BoNT/A-specific antibody, the aBoNT/A contained more BoNT/A-specific antibody than did the aToxoid, and aBoNT/A was as effective as commercial rabbit antibody. The aToxoid provided no protection against BoNT/A in a standard mouse neutralization assay; however, 1 mg of PEG-extracted aBoNT/A neutralized 4,000 lethal doses of BoNT/A injected intraperitoneally. Based on these results, we calculated that in 1 month one hen could produce more than 100 liters of antibody detection reagents or enough antibody to neutralize approximately 11.6 million mouse lethal doses of botulinum toxin. Utilization of an egg antibody platform is potentially rapid (28 to 70 days) and scalable to kilogram quantities using current egg production facilities with as few as 1,000 hens.

  11. International Network for Comparison of HIV Neutralization Assays: The NeutNet Report II

    NARCIS (Netherlands)

    Heyndrickx, Leo; Heath, Alan; Sheik-Khalil, Enas; Alcami, Jose; Bongertz, Vera; Jansson, Marianne; Malnati, Mauro; Montefiori, David; Moog, Christiane; Morris, Lynn; Osmanov, Saladin; Polonis, Victoria; Ramaswamy, Meghna; Sattentau, Quentin; Tolazzi, Monica; Schuitemaker, Hanneke; Willems, Betty; Wrin, Terri; Fenyö, Eva Maria; Scarlatti, Gabriella

    2012-01-01

    Background: Neutralizing antibodies provide markers for vaccine-induced protective immunity in many viral infections. By analogy, HIV-1 neutralizing antibodies induced by immunization may well predict vaccine effectiveness. Assessment of neutralizing antibodies is therefore of primary importance,

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

    Directory of Open Access Journals (Sweden)

    Michael A. Partridge

    2016-01-01

    Full Text Available 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, and electrochemiluminescence-based technologies. The most commonly used method is a bridging assay, performed in an ELISA or on the Meso Scale Discovery platform. In this report, we aim to review the emerging new assay technologies that can complement or address challenges associated with the bridging assay format in screening and confirmation of ADAs. We also summarize generic anti-drug antibody assays that do not require drug-specific reagents for nonclinical studies. These generic assays significantly reduce assay development efforts and, therefore, shorten the assay readiness timeline.

  13. Neutralizing and non-neutralizing monoclonal antibodies against dengue virus E protein derived from a naturally infected patient

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    Isern Sharon

    2010-02-01

    Full Text Available Abstract Background Antibodies produced in response to infection with any of the four serotypes of dengue virus generally provide homotypic immunity. However, prior infection or circulating maternal antibodies can also mediate a non-protective antibody response that can enhance the course of disease in a subsequent heterotypic infection. Naturally occurring human monoclonal antibodies can help us understand the protective and pathogenic roles of the humoral immune system in dengue virus infection. Results Epstein-Barr Virus (EBV transformation of B cells isolated from the peripheral blood of a human subject with previous dengue infection was performed. B cell cultures were screened by ELISA for antibodies to dengue (DENV envelope (E protein. ELISA positive cultures were cloned by limiting dilution. Three IgG1 human monoclonal antibodies (HMAbs were purified and their binding specificity to E protein was verified by ELISA and biolayer interferometry. Neutralization and enhancement assays were conducted in epithelial and macrophage-like cell lines, respectively. All three HMAbs bound to E from at least two of the four DENV serotypes, one of the HMAbs was neutralizing, and all were able to enhance DENV infection. Conclusions HMAbs against DENV can be successfully generated by EBV transformation of B cells from patients at least two years after naturally acquired DENV infections. These antibodies show different patterns of cross-reactivity, neutralizing, and enhancement activity.

  14. International network for comparison of HIV neutralization assays: the NeutNet report II.

    Directory of Open Access Journals (Sweden)

    Leo Heyndrickx

    Full Text Available BACKGROUND: Neutralizing antibodies provide markers for vaccine-induced protective immunity in many viral infections. By analogy, HIV-1 neutralizing antibodies induced by immunization may well predict vaccine effectiveness. Assessment of neutralizing antibodies is therefore of primary importance, but is hampered by the fact that we do not know which assay(s can provide measures of protective immunity. An international collaboration (NeutNet involving 18 different laboratories previously compared different assays using monoclonal antibodies (mAbs and soluble CD4 (Phase I study. METHODS: In the present study (Phase II, polyclonal reagents were evaluated by 13 laboratories. Each laboratory evaluated nine plasmas against an 8 virus panel representing different genetic subtypes and phenotypes. TriMab, a mixture of three mAbs, was used as a positive control allowing comparison of the results with Phase I in a total of nine different assays. The assays used either uncloned virus produced in peripheral blood mononuclear cells (PBMCs (Virus Infectivity Assays, VIA, or Env (gp160-pseudotyped viruses (pseudoviruses, PSV produced in HEK293T cells from molecular clones or from uncloned virus. Target cells included PBMC and genetically engineered cell lines in either single- or multiple-cycle infection format. Infection was quantified by using a range of assay read-outs including extra- or intra-cellular p24 antigen detection, luciferase, beta-galactosidase or green fluorescent protein (GFP reporter gene expression. FINDINGS: Using TriMab, results of Phase I and Phase II were generally in agreement for six of the eight viruses tested and confirmed that the PSV assay is more sensitive than PBMC (p = 0.014. Comparisons with the polyclonal reagents showed that sensitivities were dependent on both virus and plasma. CONCLUSIONS: Here we further demonstrate clear differences in assay sensitivities that were dependent on both the neutralizing reagent and the virus

  15. International network for comparison of HIV neutralization assays: the NeutNet report II.

    Science.gov (United States)

    Heyndrickx, Leo; Heath, Alan; Sheik-Khalil, Enas; Alcami, Jose; Bongertz, Vera; Jansson, Marianne; Malnati, Mauro; Montefiori, David; Moog, Christiane; Morris, Lynn; Osmanov, Saladin; Polonis, Victoria; Ramaswamy, Meghna; Sattentau, Quentin; Tolazzi, Monica; Schuitemaker, Hanneke; Willems, Betty; Wrin, Terri; Fenyö, Eva Maria; Scarlatti, Gabriella

    2012-01-01

    Neutralizing antibodies provide markers for vaccine-induced protective immunity in many viral infections. By analogy, HIV-1 neutralizing antibodies induced by immunization may well predict vaccine effectiveness. Assessment of neutralizing antibodies is therefore of primary importance, but is hampered by the fact that we do not know which assay(s) can provide measures of protective immunity. An international collaboration (NeutNet) involving 18 different laboratories previously compared different assays using monoclonal antibodies (mAbs) and soluble CD4 (Phase I study). In the present study (Phase II), polyclonal reagents were evaluated by 13 laboratories. Each laboratory evaluated nine plasmas against an 8 virus panel representing different genetic subtypes and phenotypes. TriMab, a mixture of three mAbs, was used as a positive control allowing comparison of the results with Phase I in a total of nine different assays. The assays used either uncloned virus produced in peripheral blood mononuclear cells (PBMCs) (Virus Infectivity Assays, VIA), or Env (gp160)-pseudotyped viruses (pseudoviruses, PSV) produced in HEK293T cells from molecular clones or from uncloned virus. Target cells included PBMC and genetically engineered cell lines in either single- or multiple-cycle infection format. Infection was quantified by using a range of assay read-outs including extra- or intra-cellular p24 antigen detection, luciferase, beta-galactosidase or green fluorescent protein (GFP) reporter gene expression. Using TriMab, results of Phase I and Phase II were generally in agreement for six of the eight viruses tested and confirmed that the PSV assay is more sensitive than PBMC (p = 0.014). Comparisons with the polyclonal reagents showed that sensitivities were dependent on both virus and plasma. Here we further demonstrate clear differences in assay sensitivities that were dependent on both the neutralizing reagent and the virus. Consistent with the Phase I study, we recommend

  16. Ocular Safety of Intravitreal Connective Tissue Growth Factor Neutralizing Antibody.

    Science.gov (United States)

    Motevasseli, Tahmineh; Daftarian, Narsis; Kanavi, Mozhgan Rezaei; Ahmadieh, Hamid; Bagheri, Abouzar; Hosseini, Seyed Bagher; Ansari, Shabnam; Soheili, Zahra-Soheila

    2017-08-01

    To detect the safety of intravitreal injection of anti-connective tissue growth factor (CTGF) (IVAC) in rat eyes in order to apply this neutralizing antibody for experimental animal studies. Forty-five Lister Hooded male pigmented rats were divided into five groups that received IVAC (2 μl) corresponding to the doses of 10 (B), 20 (C), 50 (D), and 100 μg/ml (E), equal to 1.25, 2.5, 6.25, and 12.5 µg/ml of antibody concentration in rat vitreous, respectively. The sham group (A) received 2 μl of normal saline. Full field electroretinography (ERG) was performed at baseline and on days 7 and 28 after IVAC. The animals were euthanized and the corresponding eyes were subjected to routine histopathology, immunohistochemistry for glial fibrillary acidic protein (GFAP), and terminal transferase dUTP nick end-labeling (TUNEL) assay. Scotopic rod b-wave amplitude and maximal combined b-wave amplitude were 111.89 ± 71.2 and 178.57 ± 55.58 μV, respectively, at baseline which significantly reduced to 79.31 ± 52.59 and 128.73 ± 41.61 μV, respectively, after 28 days in group E (p < 0.05). There was no significant reduction of amplitudes in other groups with lower doses of anti-CTGF antibody. Retinal ganglion cells were significantly decreased in group E as compared to other groups. GFAP immune reactivity was not significant in any of the groups. TUNEL test showed inner retinal neural cell apoptosis only in group E. ERG, histopathologic, and apoptotic assays revealed no toxic effects of 10-50 μg/ml of IVAC in rat eyes. Using 100 μg/ml IVAC led to a significant toxic effect in terms of functional, histopathologic, and TUNEL findings.

  17. Induction of human immunodeficiency virus neutralizing antibodies using fusion complexes.

    Science.gov (United States)

    Zipeto, Donato; Matucci, Andrea; Ripamonti, Chiara; Scarlatti, Gabriella; Rossolillo, Paola; Turci, Marco; Sartoris, Silvia; Tridente, Giuseppe; Bertazzoni, Umberto

    2006-05-01

    Human immunodeficiency virus-1 (HIV-1) infects cells by membrane fusion that is mediated by the envelope proteins gp120/gp41 and the cellular receptors CD4 and CCR5. During this process, some conserved viral epitopes are temporarily exposed and may induce a neutralizing antibody response when fixed in the fusogenic conformation. These transient structures are conserved and may be effective antigens for use in an anti-HIV-1 vaccine. In this study we tested different conditions of preparation of fusion complexes inducing neutralizing antibodies against both R5 and X4 tropic HIV-1 strains. Cell lines expressing HIV-1 gp120/gp41 and CD4-CCR5 were prepared and conditions for producing fusion complexes were tested. Complexes produced at different temperature and fixative combinations were used to immunize mice. Results indicated that (a) fusion complexes prepared at either 21 degrees C, 30 degrees C or 37 degrees C were immunogenic and induced neutralizing antibodies against both R5 and X4 HIV-1 heterologous isolates; (b) after extensive purification of antibodies there was no cytotoxic effect; (c) complexes prepared at 37 degrees C were more immunogenic and induced higher titers of neutralizing antibodies than complexes prepared at either 21 degrees C or 30 degrees C; (d) the fixative used did not affect the titer of neutralizing antibodies except for glutaraldehyde which was ineffective; (e) the neutralizing activity was retained after CD4-CCR5 antibody removal. The production of higher titers of neutralizing antibody with fusion complexes prepared at 37 degrees C, as compared to lower temperatures, may be related to the induction of antibodies against many different conformation intermediates that subsequently act synergistically at different steps in the fusion process.

  18. Antiviral Therapy by HIV-1 Broadly Neutralizing and Inhibitory Antibodies

    Directory of Open Access Journals (Sweden)

    Zhiqing Zhang

    2016-11-01

    Full Text Available Human immunodeficiency virus type 1 (HIV-1 infection causes acquired immune deficiency syndrome (AIDS, a global epidemic for more than three decades. HIV-1 replication is primarily controlled through antiretroviral therapy (ART but this treatment does not cure HIV-1 infection. Furthermore, there is increasing viral resistance to ART, and side effects associated with long-term therapy. Consequently, there is a need of alternative candidates for HIV-1 prevention and therapy. Recent advances have discovered multiple broadly neutralizing antibodies against HIV-1. In this review, we describe the key epitopes on the HIV-1 Env protein and the reciprocal broadly neutralizing antibodies, and discuss the ongoing clinical trials of broadly neutralizing and inhibitory antibody therapy as well as antibody combinations, bispecific antibodies, and methods that improve therapeutic efficacy by combining broadly neutralizing antibodies (bNAbs with latency reversing agents. Compared with ART, HIV-1 therapeutics that incorporate these broadly neutralizing and inhibitory antibodies offer the advantage of decreasing virus load and clearing infected cells, which is a promising prospect in HIV-1 prevention and treatment.

  19. HIV-1 binding and neutralizing antibodies of injecting drug users

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    E.P. Ouverney

    2005-09-01

    Full Text Available Previous studies have demonstrated a stronger seroreactivity against some synthetic peptides responsible for inducing neutralizing antibodies in injecting drug users (IDU compared to that of individuals sexually infected with HIV-1 (S, but the effectiveness in terms of the neutralizing ability of these antibodies has not been evaluated. Our objective was to study the humoral immune response of IDU by determining the specificity of their antibodies and the presence of neutralizing antibodies. The neutralization capacity against the HIV-1 isolate MN (genotype B, the primary HIV-1 isolate 95BRRJ021 (genotype F, and the seroreactivity with peptides known to induce neutralizing antibodies, from the V2 and V3 loops of different HIV-1 subtypes, were analyzed. Seroreactivity indicates that IDU plasma are more likely to recognize a broader range of peptides than S plasma, with significantly higher titers, especially of V3 peptides. Similar neutralization frequencies of the MN isolate were observed in plasma of the IDU (16/47 and S (20/60 groups in the 1:10 dilution. The neutralization of the 95BRRJ021 isolate was more frequently observed for plasma from the S group (15/23 than from the IDU group (15/47, P = 0.0108. No correlation between neutralization and seroreactivity with the peptides tested was observed. These results suggest that an important factor responsible for the extensive and broad humoral immune response observed in IDU is their infection route. There was very little difference in neutralizing antibody response between the IDU and S groups despite their differences in seroreactivity and health status.

  20. International network for comparison of HIV neutralization assays: the NeutNet report.

    Science.gov (United States)

    Fenyö, Eva Maria; Heath, Alan; Dispinseri, Stefania; Holmes, Harvey; Lusso, Paolo; Zolla-Pazner, Susan; Donners, Helen; Heyndrickx, Leo; Alcami, Jose; Bongertz, Vera; Jassoy, Christian; Malnati, Mauro; Montefiori, David; Moog, Christiane; Morris, Lynn; Osmanov, Saladin; Polonis, Victoria; Sattentau, Quentin; Schuitemaker, Hanneke; Sutthent, Ruengpung; Wrin, Terri; Scarlatti, Gabriella

    2009-01-01

    Neutralizing antibody assessments play a central role in human immunodeficiency virus type-1 (HIV-1) vaccine development but it is unclear which assay, or combination of assays, will provide reliable measures of correlates of protection. To address this, an international collaboration (NeutNet) involving 18 independent participants was organized to compare different assays. Each laboratory evaluated four neutralizing reagents (TriMab, 447-52D, 4E10, sCD4) at a given range of concentrations against a panel of 11 viruses representing a wide range of genetic subtypes and phenotypes. A total of 16 different assays were compared. The assays utilized either uncloned virus produced in peripheral blood mononuclear cells (PBMCs) (virus infectivity assays, VI assays), or their Env-pseudotyped (gp160) derivatives produced in 293T cells (PSV assays) from molecular clones or uncloned virus. Target cells included PBMC and genetically-engineered cell lines in either a single- or multiple-cycle infection format. Infection was quantified by using a range of assay read-outs that included extracellular or intracellular p24 antigen detection, RNA quantification and luciferase and beta-galactosidase reporter gene expression. PSV assays were generally more sensitive than VI assays, but there were important differences according to the virus and inhibitor used. For example, for TriMab, the mean IC50 was always lower in PSV than in VI assays. However, with 4E10 or sCD4 some viruses were neutralized with a lower IC50 in VI assays than in the PSV assays. Inter-laboratory concordance was slightly better for PSV than for VI assays with some viruses, but for other viruses agreement between laboratories was limited and depended on both the virus and the neutralizing reagent. The NeutNet project demonstrated clear differences in assay sensitivity that were dependent on both the neutralizing reagent and the virus. No single assay was capable of detecting the entire spectrum of neutralizing

  1. International network for comparison of HIV neutralization assays: the NeutNet report.

    Directory of Open Access Journals (Sweden)

    Eva Maria Fenyö

    Full Text Available Neutralizing antibody assessments play a central role in human immunodeficiency virus type-1 (HIV-1 vaccine development but it is unclear which assay, or combination of assays, will provide reliable measures of correlates of protection. To address this, an international collaboration (NeutNet involving 18 independent participants was organized to compare different assays.Each laboratory evaluated four neutralizing reagents (TriMab, 447-52D, 4E10, sCD4 at a given range of concentrations against a panel of 11 viruses representing a wide range of genetic subtypes and phenotypes. A total of 16 different assays were compared. The assays utilized either uncloned virus produced in peripheral blood mononuclear cells (PBMCs (virus infectivity assays, VI assays, or their Env-pseudotyped (gp160 derivatives produced in 293T cells (PSV assays from molecular clones or uncloned virus. Target cells included PBMC and genetically-engineered cell lines in either a single- or multiple-cycle infection format. Infection was quantified by using a range of assay read-outs that included extracellular or intracellular p24 antigen detection, RNA quantification and luciferase and beta-galactosidase reporter gene expression.PSV assays were generally more sensitive than VI assays, but there were important differences according to the virus and inhibitor used. For example, for TriMab, the mean IC50 was always lower in PSV than in VI assays. However, with 4E10 or sCD4 some viruses were neutralized with a lower IC50 in VI assays than in the PSV assays. Inter-laboratory concordance was slightly better for PSV than for VI assays with some viruses, but for other viruses agreement between laboratories was limited and depended on both the virus and the neutralizing reagent.The NeutNet project demonstrated clear differences in assay sensitivity that were dependent on both the neutralizing reagent and the virus. No single assay was capable of detecting the entire spectrum of

  2. Development and characterization of human monoclonal antibodies that neutralize multiple TGFβ isoforms.

    Science.gov (United States)

    Bedinger, Daniel; Lao, Llewelyn; Khan, Shireen; Lee, Steve; Takeuchi, Toshihiko; Mirza, Amer M

    2016-01-01

    Transforming growth factor (TGF)β levels are elevated in, and drive the progression of, numerous disease states such as advanced metastatic cancer and systemic and ocular fibrosis. There are 3 main isoforms, TGFβ1, 2, and 3. As multiple TGFβ isoforms are involved in disease processes, maximal therapeutic efficacy may require neutralization of 2 or more of the TGFβ isoforms. Fully human antibody phage display libraries were used to discover a number of antibodies that bind and neutralize various combinations of TGFβ1, 2 or 3. The primary panning did not yield any uniformly potent pan-isoform neutralizing antibodies; therefore, an antibody that displayed potent TGFβ 1, 2 inhibition, but more modest affinity versus TGFβ3, was affinity matured by shuffling with a light chain sub-library and further screening. This process yielded a high affinity pan-isoform neutralizing clone. Antibodies were analyzed and compared by binding affinity, as well as receptor and epitope competition by surface plasmon resonance methods. The antibodies were also shown to neutralize TGFβ effects in vitro in 3 assays: 1) interleukin (IL)-4 induced HT-2 cell proliferation; 2) TGFβ-mediated IL-11 release by A549 cells; and 3) decreasing SMAD2 phosphorylation in Detroit 562 cells. The antibodies' potency in these in vitro assays correlated well with their isoform-specific affinities. Furthermore, the ability of the affinity-matured clone to decrease tumor burden in a Detroit 562 xenograft study was superior to that of the parent clone. This affinity-matured antibody acts as a very potent inhibitor of all 3 main isoforms of TGFβ and may have utility for therapeutic intervention in human disease.

  3. Neutralizing Antibodies and Pathogenesis of Hepatitis C Virus Infection

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    Françoise Stoll-Keller

    2012-10-01

    Full Text Available Hepatitis C virus (HCV infection is a major cause of chronic liver disease worldwide. The interplay between the virus and host innate and adaptive immune responses determines the outcome of infection. There is increasing evidence that host neutralizing responses play a relevant role in the resulting pathogenesis. Furthermore, viral evasion from host neutralizing antibodies has been revealed to be an important contributor in leading both to viral persistence in acute liver graft infection following liver transplantation, and to chronic viral infection. The development of novel model systems to study HCV entry and neutralization has allowed a detailed understanding of the molecular mechanisms of virus-host interactions during antibody-mediated neutralization. The understanding of these mechanisms will ultimately contribute to the development of novel antiviral preventive strategies for liver graft infection and an urgently needed vaccine. This review summarizes recent concepts of the role of neutralizing antibodies in viral clearance and protection, and highlights consequences of viral escape from neutralizing antibodies in the pathogenesis of HCV infection.

  4. Production and assay of forskolin antibodies

    International Nuclear Information System (INIS)

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

    1986-01-01

    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 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 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 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

  5. Maturation Pathways of Cross-Reactive HIV-1 Neutralizing Antibodies

    Directory of Open Access Journals (Sweden)

    Dimiter S. Dimitrov

    2009-11-01

    Full Text Available Several human monoclonal antibodies (hmAbs and antibody fragments, including the best characterized in terms of structure-function b12 and Fab X5, exhibit relatively potent and broad HIV-1 neutralizing activity. However, the elicitation of b12 or b12-like antibodies in vivo by vaccine immunogens based on the HIV-1 envelope glycoprotein (Env has not been successful. B12 is highly divergent from the closest corresponding germline antibody while X5 is less divergent. We have hypothesized that the relatively high degree of specific somatic hypermutations may preclude binding of the HIV-1 envelope glycoprotein (Env to closest germline antibodies, and that identifying antibodies that are intermediates in the pathways to maturation could help design novel vaccine immunogens to guide the immune system for their enhanced elicitation. In support of this hypothesis we have previously found that a germline-like b12 (monovalent and bivalent scFv as an Fc fusion protein or IgG lacks measurable binding to an Env as measured by ELISA with a sensitivity in the μM range [1]; here we present evidence confirming and expanding these findings for a panel of Envs. In contrast, a germline-like scFv X5 bound Env with high (nM affinity. To begin to explore the maturation pathways of these antibodies we identified several possible b12 intermediate antibodies and tested their neutralizing activity. These intermediate antibodies neutralized only some HIV-1 isolates and with relatively weak potency. In contrast, germline-like scFv X5 neutralized a subset of the tested HIV-1 isolates with comparable efficiencies to that of the mature X5. These results could help explain the relatively high immunogenicity of the coreceptor binding site on gp120 and the abundance of CD4-induced (CD4i antibodies in HIV-1-infected patients (X5 is a CD4i antibody as well as the maturation pathway of X5. They also can help identify antigens that can bind specifically to b12 germline and

  6. Broadly-Reactive Neutralizing and Non-neutralizing Antibodies Directed against the H7 Influenza Virus Hemagglutinin Reveal Divergent Mechanisms of Protection.

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    Gene S Tan

    2016-04-01

    Full Text Available In the early spring of 2013, Chinese health authorities reported several cases of H7N9 influenza virus infections in humans. Since then the virus has established itself at the human-animal interface in Eastern China and continues to cause several hundred infections annually. In order to characterize the antibody response to the H7N9 virus we generated several mouse monoclonal antibodies against the hemagglutinin of the A/Shanghai/1/13 (H7N9 virus. Of particular note are two monoclonal antibodies, 1B2 and 1H5, that show broad reactivity to divergent H7 hemagglutinins. Monoclonal antibody 1B2 binds to viruses of the Eurasian and North American H7 lineages and monoclonal antibody 1H5 reacts broadly to virus isolates of the Eurasian lineage. Interestingly, 1B2 shows broad hemagglutination inhibiting and neutralizing activity, while 1H5 fails to inhibit hemagglutination and demonstrates no neutralizing activity in vitro. However, both monoclonal antibodies were highly protective in an in vivo passive transfer challenge model in mice, even at low doses. Experiments using mutant antibodies that lack the ability for Fc/Fc-receptor and Fc/complement interactions suggest that the protection provided by mAb 1H5 is, at least in part, mediated by the Fc-fragment of the mAb. These findings highlight that a protective response to a pathogen may not only be due to neutralizing antibodies, but can also be the result of highly efficacious non-neutralizing antibodies not readily detected by classical in vitro neutralization or hemagglutination inhibition assays. This is of interest because H7 influenza virus vaccines induce only low hemagglutination inhibiting antibody titers while eliciting robust antibody titers as measured by ELISA. Our data suggest that these binding but non-neutralizing antibodies contribute to protection in vivo.

  7. Neutralizing activities of caprine antibodies towards conserved regions of the HCV envelope glycoprotein E2

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    El-Shenawy Reem

    2011-08-01

    Full Text Available Abstract Anti HCV vaccine is not currently available and the present antiviral therapies fail to cure approximately half of the treated HCV patients. This study was designed to assess the immunogenic properties of genetically conserved peptides derived from the C-terminal region of HVR-1 and test their neutralizing activities in a step towards developing therapeutic and/or prophylactic immunogens against HCV infection. Antibodies were generated by vaccination of goats with synthetic peptides derived from HCV E2. Viral neutralizing capacity of the generated anti E2 antibodies was tested using in vitro assays. Goats immunized with E2 synthetic peptides termed p412 [a.a 412-419], p430 [a.a 430-447] and p517 [a.a 517-531] generated high titers of antibody responses 2 to 4.5 fold higher than comparable titers of antibodies to the same epitopes in chronic HCV patients. In post infection experiments of native HCV into cultured Huh7.5 cells anti p412 and anti p 517 were proven to be neutralizing to HCV genotype 4a from patients' sera (87.5% and 75% respectively. On the contrary anti p430 exhibited weak viral neutralization capacity on the same samples (31.25%. Furthermore Ab mixes containing anti p430 exhibited reduced viral neutralization properties. From these experiments one could predict that neutralization by Abs towards different E2-epitopes varies considerably and success in the enrichment of neutralization epitope-specific antibodies may be accompanied by favorable results in combating HCV infection. Also, E2 conserved peptides p517 and p412 represent potential components of a candidate peptide vaccine against HCV infection.

  8. Thermodynamic Mechanism for the Evasion of Antibody Neutralization in Flaviviruses

    Science.gov (United States)

    2015-01-01

    Mutations in the epitopes of antigenic proteins can confer viral resistance to antibody-mediated neutralization. However, the fundamental properties that characterize epitope residues and how mutations affect antibody binding to alter virus susceptibility to neutralization remain largely unknown. To address these questions, we used an ensemble-based algorithm to characterize the effects of mutations on the thermodynamics of protein conformational fluctuations. We applied this method to the envelope protein domain III (ED3) of two medically important flaviviruses: West Nile and dengue 2. We determined an intimate relationship between the susceptibility of a residue to thermodynamic perturbations and epitope location. This relationship allows the successful identification of the primary epitopes in each ED3, despite their high sequence and structural similarity. Mutations that allow the ED3 to evade detection by the antibody either increase or decrease conformational fluctuations of the epitopes through local effects or long-range interactions. Spatially distant interactions originate in the redistribution of conformations of the ED3 ensembles, not through a mechanically connected array of contiguous amino acids. These results reconcile previous observations of evasion of neutralization by mutations at a distance from the epitopes. Finally, we established a quantitative correlation between subtle changes in the conformational fluctuations of the epitope and large defects in antibody binding affinity. This correlation suggests that mutations that allow viral growth, while reducing neutralization, do not generate significant structural changes and underscores the importance of protein fluctuations and long-range interactions in the mechanism of antibody-mediated neutralization resistance. PMID:24950171

  9. Structural Basis for Recognition of Human Enterovirus 71 by a Bivalent Broadly Neutralizing Monoclonal Antibody.

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    Xiaohua Ye

    2016-03-01

    Full Text Available Enterovirus 71 (EV71 is the main pathogen responsible for hand, foot and mouth disease with severe neurological complications and even death in young children. We have recently identified a highly potent anti-EV71 neutralizing monoclonal antibody, termed D5. Here we investigated the structural basis for recognition of EV71 by the antibody D5. Four three-dimensional structures of EV71 particles in complex with IgG or Fab of D5 were reconstructed by cryo-electron microscopy (cryo-EM single particle analysis all at subnanometer resolutions. The most critical EV71 mature virion-Fab structure was resolved to a resolution of 4.8 Å, which is rare in cryo-EM studies of virus-antibody complex so far. The structures reveal a bivalent binding pattern of D5 antibody across the icosahedral 2-fold axis on mature virion, suggesting that D5 binding may rigidify virions to prevent their conformational changes required for subsequent RNA release. Moreover, we also identified that the complementary determining region 3 (CDR3 of D5 heavy chain directly interacts with the extremely conserved VP1 GH-loop of EV71, which was validated by biochemical and virological assays. We further showed that D5 is indeed able to neutralize a variety of EV71 genotypes and strains. Moreover, D5 could potently confer protection in a mouse model of EV71 infection. Since the conserved VP1 GH-loop is involved in EV71 binding with its uncoating receptor, the scavenger receptor class B, member 2 (SCARB2, the broadly neutralizing ability of D5 might attribute to its inhibition of EV71 from binding SCARB2. Altogether, our results elucidate the structural basis for the binding and neutralization of EV71 by the broadly neutralizing antibody D5, thereby enhancing our understanding of antibody-based protection against EV71 infection.

  10. Neutralizing antibodies in cats infected with feline immunodeficiency virus.

    NARCIS (Netherlands)

    F. Tozzini; D. Matteucci; P. Bandecchi; F. Baldinotti; C.H.J. Siebelink (Kees); A.D.M.E. Osterhaus (Albert); M. Bendinelli

    1993-01-01

    textabstractSera from cats experimentally infected with five isolates of feline immunodeficiency virus (FIV) from various geographical regions and from FIV enzyme-linked immunosorbent assay-seropositive field cats from four European countries neutralized the Petaluma strain of FIV (FIV-P),

  11. Study on quantification of HBs-antibody by immunoradiometric assay

    International Nuclear Information System (INIS)

    Kondo, Yuichi; Itoi, Yoshihiro; Kajiyama, Shizuo

    1989-01-01

    Quantification of HBs-antibody assay was carried out using a commercialized assay kit and standard solutions of HBs-antibody recognised as 1 st reference preparation of hepatitis B immunogloblin by WHO. Standard curve of HBs-antibody was drawn with the function of 3D-spline and the correlation factor was obtained as r = 0.999. Coefficient of intra-assay variance was 3.8 % and that of inter-assay variance was 7.8 %. Dilution tests showed satisfactory results in the range of 2-16 times. Correlation between value of cut-off indices and concentration of HBs-antibody was obtained as the formula of y = 2.599 x-3.894 (r = 0.992) and 2.1 of cut-off index corresponded to about 5 mIU/ml of HBs-antibody concentration. (author)

  12. Characterization of human monoclonal antibodies that neutralize multiple poliovirus serotypes.

    Science.gov (United States)

    Puligedda, Rama Devudu; Kouiavskaia, Diana; Al-Saleem, Fetweh H; Kattala, Chandana Devi; Nabi, Usman; Yaqoob, Hamid; Bhagavathula, V Sandeep; Sharma, Rashmi; Chumakov, Konstantin; Dessain, Scott K

    2017-10-04

    Following the eradication of wild poliovirus (PV), achieving and maintaining a polio-free status will require eliminating potentially pathogenic PV strains derived from the oral attenuated vaccine. For this purpose, a combination of non-cross-resistant drugs, such as small molecules and neutralizing monoclonal antibodies (mAbs), may be ideal. We previously isolated chimpanzee and human mAbs capable of neutralizing multiple PV types (cross-neutralization). Here, we describe three additional human mAbs that neutralize types 1 and 2 PV and one mAb that neutralizes all three types. Most bind conformational epitopes and have unusually long heavy chain complementarity determining 3 domains (HC CDR3). We assessed the ability of the mAbs to neutralize A12 escape mutant PV strains, and found that the neutralizing activities of the mAbs were disrupted by different amino acid substitutions. Competitive binding studies further suggested that the specific mAb:PV interactions that enable cross-neutralization differ among mAbs and serotypes. All of the cloned mAbs bind PV in the vicinity of the "canyon", a circular depression around the 5-fold axis of symmetry through which PV recognizes its cellular receptor. We were unable to generate escape mutants to two of the mAbs, suggesting that their epitopes are important for the PV life cycle. These data indicate that PV cross-neutralization involves binding to highly conserved structures within the canyon that binds to the cellular receptor. These may be facilitated by the long HC CDR3 domains, which may adopt alternative binding configurations. We propose that the human and chimpanzee mAbs described here could have potential as anti-PV therapeutics. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Analysis of memory B cell responses and isolation of novel monoclonal antibodies with neutralizing breadth from HIV-1-infected individuals.

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    Davide Corti

    2010-01-01

    Full Text Available The isolation of human monoclonal antibodies (mAbs that neutralize a broad spectrum of primary HIV-1 isolates and the characterization of the human neutralizing antibody B cell response to HIV-1 infection are important goals that are central to the design of an effective antibody-based vaccine.We immortalized IgG(+ memory B cells from individuals infected with diverse clades of HIV-1 and selected on the basis of plasma neutralization profiles that were cross-clade and relatively potent. Culture supernatants were screened using various recombinant forms of the envelope glycoproteins (Env in multiple parallel assays. We isolated 58 mAbs that were mapped to different Env surfaces, most of which showed neutralizing activity. One mAb in particular (HJ16 specific for a novel epitope proximal to the CD4 binding site on gp120 selectively neutralized a multi-clade panel of Tier-2 HIV-1 pseudoviruses, and demonstrated reactivity that was comparable in breadth, but distinct in neutralization specificity, to that of the other CD4 binding site-specific neutralizing mAb b12. A second mAb (HGN194 bound a conserved epitope in the V3 crown and neutralized all Tier-1 and a proportion of Tier-2 pseudoviruses tested, irrespective of clade. A third mAb (HK20 with broad neutralizing activity, particularly as a Fab fragment, recognized a highly conserved epitope in the HR-1 region of gp41, but showed striking assay-dependent selectivity in its activity.This study reveals that by using appropriate screening methods, a large proportion of memory B cells can be isolated that produce mAbs with HIV-1 neutralizing activity. Three of these mAbs show unusual breadth of neutralization and therefore add to the current panel of HIV-1 neutralizing antibodies with potential for passive protection and template-based vaccine design.

  14. A fluorescence sedimentation assay for dsDNA antibodies

    DEFF Research Database (Denmark)

    Duus, K; Draborg, A H; Güven, E

    2017-01-01

    The Farr assay is a radioimmunoassay (RIA) for dsDNA antibodies, based on antibody precipitation using ammonium sulphate and quantification using radio-labelled dsDNA. The RIA-Farr assay offers outstanding clinical specificity and sensitivity for systemic lupus erythematosus (SLE) compared to other...... on precipitation with polyethylene glycol (PEG) and fluorescence of EvaGreen intercalated in dsDNA as detection principle. As dsDNA antibodies are quantified using fluorescence, the disadvantages of working with radioactivity are eliminated. The Fluoro-Farr assay was developed and validated, and the diagnostic...

  15. HIV-1 subtype C superinfected individuals mount low autologous neutralizing antibody responses prior to intrasubtype superinfection

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    Basu Debby

    2012-09-01

    Full Text Available Abstract Background The potential role of antibodies in protection against intra-subtype HIV-1 superinfection remains to be understood. We compared the early neutralizing antibody (NAb responses in three individuals, who were superinfected within one year of primary infection, to ten matched non-superinfected controls from a Zambian cohort of subtype C transmission cases. Sequence analysis of single genome amplified full-length envs from a previous study showed limited diversification in the individuals who became superinfected with the same HIV-1 subtype within year one post-seroconversion. We hypothesized that this reflected a blunted NAb response, which may have made these individuals more susceptible to superinfection. Results Neutralization assays showed that autologous plasma NAb responses to the earliest, and in some cases transmitted/founder, virus were delayed and had low to undetectable titers in all three superinfected individuals prior to superinfection. In contrast, NAbs with a median IC50 titer of 1896 were detected as early as three months post-seroconversion in non-superinfected controls. Early plasma NAbs in all subjects showed limited but variable levels of heterologous neutralization breadth. Superinfected individuals also exhibited a trend toward lower levels of gp120- and V1V2-specific IgG binding antibodies but higher gp120-specific plasma IgA binding antibodies. Conclusions These data suggest that the lack of development of IgG antibodies, as reflected in autologous NAbs as well as gp120 and V1V2 binding antibodies to the primary infection virus, combined with potentially competing, non-protective IgA antibodies, may increase susceptibility to superinfection in the context of settings where a single HIV-1 subtype predominates.

  16. Neutralization potential as an assay of alkalinity of environmental solids

    International Nuclear Information System (INIS)

    Grube, W.E.Jr.; Ammons, J.T.

    1993-01-01

    The method to determine neutralizing equivalence of agricultural limestone has been applied to quantify the amount of bases present in a broad diversity of mineral materials, solid reagents, and products involved in environmental processes. The capacity to neutralize native or imposed acidity must be known in many processes in order to preserve near-neutral material. The standard method for assaying agricultural limestones was adapted to quantify native alkalinity in calcareous rocks exposed by coal surface mining. Data from these analyses continue to provide the surface mining industry and regulating agencies with a measure of the extent to which acidic mine drainage may be neutralized by the natural components of surrounding rock strata and disturbed materials. This approach to determine base content has also been applied to commercially available industrial byproducts added to soils or wastes. Kiln dust, fly ash, sludge, and other additives have been evaluated routinely to measure their alkalinity contribution and also batch-to-batch uniformity. The application of this technique to monitor amounts of reagents added to neutralize acid waste materials by adding alkalis is discussed. Use of this procedure to evaluate different materials is documented with exemplary data. Results of analyses of a broad variety of rock and soil materials, amended soils, soil additives or amendments, industrial waste byproducts, sludge, and treated wastes are presented. Utility of the procedure for routine quality control in soil treatment, amendment uniformity, and product analysis is discussed

  17. Immunoradiometric assay for cytomegalovirus-specific IgG antibodies

    International Nuclear Information System (INIS)

    Klapper, P.E.; Cleator, G.M.; Prinja-Wolks, D.; Morris, D.J.

    1990-01-01

    An immunoradiometric assay (radio-immunosorbent test; RIST) for the detection of IgG antibodies to human herpesvirus 4 [human cytomegalovirus (CMV)] has been developed. The technique utilizes CMV antigen passively adsorbed to a polyvinyl microtitration plate and a radiolabelled murine monoclonal anti-human IgG antibody to detect binding of human antibody to the 'solid phase' reagent. The assay was optimized, and its specifity confirmed by testing paired acute and convalescent sera from patients with acute CMV or other human herpesvirus infections. To determine the assay's sensitivity 1433 blood donor sera were examined. The RIST was more sensitive than a standard complement fixation (CFT). Use of a monoclonal anti-human IgG antibody in the RIST reduced non-specific binding to the control uninfected cell antigen such that blood donor sera could be tested in the assay using only a CMV antigen without generating an unacceptable false positive rate. (author). 23 refs.; 1 tab

  18. Non-Neutralizing Antibodies Directed against HIV and Their Functions

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    Luzia M. Mayr

    2017-11-01

    Full Text Available B cells produce a plethora of anti-HIV antibodies (Abs but only few of them exhibit neutralizing activity. This was long considered a profound limitation for the enforcement of humoral immune responses against HIV-1 infection, especially since these neutralizing Abs (nAbs are extremely difficult to induce. However, increasing evidence shows that additional non-neutralizing Abs play a significant role in decreasing the viral load, leading to partial and sometimes even total protection. Mechanisms suspected to participate in protection are numerous. They involve the Fc domain of Abs as well as their Fab part, and consequently the induced Ab isotype will be determinant for their functions, as well as the quantity and quality of the Fc-receptors (FcRs expressed on immune cells. Fc-mediated inhibitory functions, such as Ab-dependent cellular cytotoxicity, antibody-dependent cellular phagocytosis, aggregation, and even immune activation have been proposed. However, as for nAbs, the non-neutralizing activities are limited to a subset of anti-HIV Abs. An improved in-depth characterization of the Abs displaying these functional responses is required for the development of new vaccination strategies, which aim to selectively trigger the B cells able to induce the right functional Ab combinations both at the right place and at the right time. This review summarizes our current knowledge on non-neutralizing functional inhibitory Abs and discusses the potential benefit of inducing them via vaccination. We also provide new insight into the roles of the FcγR-mediated Ab therapeutics in clinical trials for HIV diseases.

  19. Structural basis for the antibody neutralization of Herpes simplex virus

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Cheng-Chung; Lin, Li-Ling [Academia Sinica, Taipei 115, Taiwan (China); Academia Sinica, Taipei 115, Taiwan (China); Chan, Woan-Eng [Development Center for Biotechnology, New Taipei City 221, Taiwan (China); Ko, Tzu-Ping [Academia Sinica, Taipei 115, Taiwan (China); Academia Sinica, Taipei 115, Taiwan (China); Lai, Jiann-Shiun [Development Center for Biotechnology, New Taipei City 221, Taiwan (China); Ministry of Economic Affairs, Taipei 100, Taiwan (China); Wang, Andrew H.-J., E-mail: ahjwang@gate.sinica.edu.tw [Academia Sinica, Taipei 115, Taiwan (China); Academia Sinica, Taipei 115, Taiwan (China); Taipei Medical University, Taipei 110, Taiwan (China)

    2013-10-01

    The gD–E317-Fab complex crystal revealed the conformational epitope of human mAb E317 on HSV gD, providing a molecular basis for understanding the viral neutralization mechanism. Glycoprotein D (gD) of Herpes simplex virus (HSV) binds to a host cell surface receptor, which is required to trigger membrane fusion for virion entry into the host cell. gD has become a validated anti-HSV target for therapeutic antibody development. The highly inhibitory human monoclonal antibody E317 (mAb E317) was previously raised against HSV gD for viral neutralization. To understand the structural basis of antibody neutralization, crystals of the gD ectodomain bound to the E317 Fab domain were obtained. The structure of the complex reveals that E317 interacts with gD mainly through the heavy chain, which covers a large area for epitope recognition on gD, with a flexible N-terminal and C-terminal conformation. The epitope core structure maps to the external surface of gD, corresponding to the binding sites of two receptors, herpesvirus entry mediator (HVEM) and nectin-1, which mediate HSV infection. E317 directly recognizes the gD–nectin-1 interface and occludes the HVEM contact site of gD to block its binding to either receptor. The binding of E317 to gD also prohibits the formation of the N-terminal hairpin of gD for HVEM recognition. The major E317-binding site on gD overlaps with either the nectin-1-binding residues or the neutralizing antigenic sites identified thus far (Tyr38, Asp215, Arg222 and Phe223). The epitopes of gD for E317 binding are highly conserved between two types of human herpesvirus (HSV-1 and HSV-2). This study enables the virus-neutralizing epitopes to be correlated with the receptor-binding regions. The results further strengthen the previously demonstrated therapeutic and diagnostic potential of the E317 antibody.

  20. Post-infection immunodeficiency virus control by neutralizing antibodies.

    Directory of Open Access Journals (Sweden)

    Hiroyuki Yamamoto

    Full Text Available BACKGROUND: Unlike most acute viral infections controlled with the appearance of virus-specific neutralizing antibodies (NAbs, primary HIV infections are not met with such potent and early antibody responses. This brings into question if or how the presence of potent antibodies can contribute to primary HIV control, but protective efficacies of antiviral antibodies in primary HIV infections have remained elusive; and, it has been speculated that even NAb induction could have only a limited suppressive effect on primary HIV replication once infection is established. Here, in an attempt to answer this question, we examined the effect of passive NAb immunization post-infection on primary viral replication in a macaque AIDS model. METHODS AND FINDINGS: The inoculums for passive immunization with simian immunodeficiency virus mac239 (SIVmac239-specific neutralizing activity were prepared by purifying polyclonal immunoglobulin G from pooled plasma of six SIVmac239-infected rhesus macaques with NAb induction in the chronic phase. Passive immunization of rhesus macaques with the NAbs at day 7 after SIVmac239 challenge resulted in significant reduction of set-point plasma viral loads and preservation of central memory CD4 T lymphocyte counts, despite the limited detection period of the administered NAb responses. Peripheral lymph node dendritic cell (DC-associated viral RNA loads showed a remarkable peak with the NAb administration, and DCs stimulated in vitro with NAb-preincubated SIV activated virus-specific CD4 T lymphocytes in an Fc-dependent manner, implying antibody-mediated virion uptake by DCs and enhanced T cell priming. CONCLUSIONS: Our results present evidence indicating that potent antibody induction post-infection can result in primary immunodeficiency virus control and suggest direct and indirect contribution of its absence to initial control failure in HIV infections. Although difficulty in achieving requisite neutralizing titers for

  1. Development of Broadly Neutralizing Antibody Mimitopes for Characterization of CRF01_AE HIV-1 Antibody Responses

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    Jesse V. Schoen

    2017-10-01

    Full Text Available Mapping humoral immune responses to HIV-1 over the course of natural infection is important in understanding epitope exposure in relation to elicitation of broadly neutralizing antibodies (bNAbs, which is considered imperative for effective vaccine design. When analyzing HIV-specific immune responses, the antibody binding profiles may be a correlate for functional antibody activity. In this study, we utilized phage display technology to identify novel mimitopes that may represent Env epitope structures bound by bNAbs directed at V1V2 and V3 domains, CD4 binding site (CD4bs and the membrane proximal external region (MPER of Env. Mimitope sequence motifs were determined for each bNAb epitope. Given the ongoing vaccine development efforts in Thailand, these mimitopes that represent CD4bs and MPER epitopes were used to map immune responses of HIV-1 CRF01_AE-infected individuals with known neutralizing responses from two distinct time periods, 1996-98 and 2012-15. The more contemporary cohort showed an increase in binding breadth with binding observed for all MPER and CD4bs mimitopes, while the older cohort showed only 75% recognition of the CD4bs mimitopes and no MPER mimotope binding. Furthermore, mimitope binding profiles correlated significantly with magnitude (p=0.0036 and breadth (p=0.0358 of neutralization of a multi-subtype Tier 1 panel of pseudoviruses. These results highlight the utility of this mimitope mapping approach for detecting human plasma IgG-specificities that target known neutralizing antibody epitopes, and may also provide an indication of the plasticity of antibody binding within HIV-1 Env neutralization determinants.

  2. Towards HIV-1 remission: potential roles for broadly neutralizing antibodies.

    Science.gov (United States)

    Halper-Stromberg, Ariel; Nussenzweig, Michel C

    2016-02-01

    Current antiretroviral drug therapies do not cure HIV-1 because they do not eliminate a pool of long-lived cells harboring immunologically silent but replication-competent proviruses - termed the latent reservoir. Eliminating this reservoir and stimulating the immune response to control infection in the absence of therapy remain important but unsolved goals of HIV-1 cure research. Recently discovered broadly neutralizing antibodies (bNAbs) exhibit remarkable breadth and potency in their ability to neutralize HIV-1 in vitro, and recent studies have demonstrated new therapeutic applications for passively administered bNAbs in vivo. This Review discusses the roles bNAbs might play in HIV-1 treatment regimens, including prevention, therapy, and cure.

  3. Hepatitis C virus resistance to broadly neutralizing antibodies measured using replication-competent virus and pseudoparticles.

    Science.gov (United States)

    Wasilewski, Lisa N; Ray, Stuart C; Bailey, Justin R

    2016-11-01

    A better understanding of natural variation in neutralization resistance and fitness of diverse hepatitis C virus (HCV) envelope (E1E2) variants will be critical to guide rational development of an HCV vaccine. This work has been hindered by inadequate genetic diversity in viral panels and by a lack of standardization of HCV entry assays. Neutralization assays generally use lentiviral pseudoparticles expressing HCV envelope proteins (HCVpp) or chimeric full-length viruses that are replication competent in cell culture (HCVcc). There have been few systematic comparisons of specific infectivities of E1E2-matched HCVcc and HCVpp, and to our knowledge, neutralization of E1E2-matched HCVpp and HCVcc has never been compared using a diverse panel of human broadly neutralizing monoclonal antibodies (bNAbs) targeting distinct epitopes. Here, we describe an efficient method for introduction of naturally occurring E1E2 genes into a full-length HCV genome, producing replication-competent chimeric HCVcc. We generated diverse panels of E1E2-matched HCVcc and HCVpp and measured the entry-mediating fitness of E1E2 variants using the two systems. We also compared neutralization of E1E2-matched HCVcc and HCVpp by a diverse panel of human bNAbs targeting epitopes across E1E2. We found no correlation between specific infectivities of E1E2-matched HCVcc versus HCVpp, but found a very strong positive correlation between relative neutralization resistance of these same E1E2-matched HCVcc and HCVpp variants. These results suggest that quantitative comparisons of neutralization resistance of E1E2 variants can be made with confidence using either HCVcc or HCVpp, allowing the use of either or both systems to maximize diversity of neutralization panels.

  4. 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...

  5. Use of Monoclonal Antibodies in the Sensitive Detection and Neutralization of Botulinum Neurotoxin Serotype B

    Directory of Open Access Journals (Sweden)

    Luisa W. Cheng

    2015-11-01

    Full Text Available Botulinum neurotoxins (BoNT are some of nature’s most potent toxins. Due to potential food contamination, and bioterrorism concerns, the development of detection reagents, therapeutics and countermeasures are of urgent interest. Recently, we have developed a sensitive electrochemiluminescent (ECL immunoassay for BoNT/B, using monoclonal antibodies (mAbs MCS6-27 and anti-BoNT/B rabbit polyclonal antibodies as the capture and detector. The ECL assay detected as little as 1 pg/mL BoNT/B in the buffer matrix, surpassing the detection sensitivities of the gold standard mouse bioassays. The ECL assay also allowed detection of BoNT/B in sera matrices of up to 100% sera with negligible matrix effects. This highly-sensitive assay allowed the determination of the biological half-lives of BoNT/B holotoxin in vivo. We further tested the toxin neutralization potential of our monoclonal antibodies using the mouse systemic and oral intoxication models. A combination of mAbs protected mice in both pre- and post-exposure models to lethal doses of BoNT/B. MAbs were capable of increasing survival of animals when administered even 10 h post-intoxication in an oral model, suggesting a likely time for BoNT/B complexes to reach the blood stream. More sensitive detection assays and treatments against BoNT intoxication will greatly enhance efforts to combat botulism.

  6. Fluorescence Adherence Inhibition Assay: A Novel Functional Assessment of Blocking Virus Attachment by Vaccine-Induced Antibodies.

    Directory of Open Access Journals (Sweden)

    Atul Asati

    Full Text Available Neutralizing antibodies induced by vaccination or natural infection play a critically important role in protection against the viral diseases. In general, neutralization of the viral infection occurs via two major pathways: pre- and post-attachment modes, the first being the most important for such infections as influenza and polio, the latter being significant for filoviruses. Neutralizing capacity of antibodies is typically evaluated by virus neutralization assays that assess reduction of viral infectivity to the target cells in the presence of functional antibodies. Plaque reduction neutralization test, microneutralization and immunofluorescent assays are often used as gold standard virus neutralization assays. However, these methods are associated with several important prerequisites such as use of live virus requiring safety precautions, tedious evaluation procedure and long assessment time. Hence, there is a need for a robust, inexpensive high throughput functional assay that can be performed rapidly using inactivated virus, without extensive safety precautions. Herein, we report a novel high throughput Fluorescence Adherence Inhibition assay (fADI using inactivated virus labeled with fluorescent secondary antibodies virus and Vero cells or erythrocytes as targets. It requires only few hours to assess pre-attachment neutralizing capacity of donor sera. fADI assay was tested successfully on donors immunized with polio, yellow fever and influenza vaccines. To further simplify and improve the throughput of the assay, we have developed a mathematical approach for calculating the 50% titers from a single sample dilution, without the need to analyze multi-point titration curves. Assessment of pre- and post-vaccination human sera from subjects immunized with IPOL®, YF-VAX® and 2013-2014 Fluzone® vaccines demonstrated high efficiency of the assay. The results correlated very well with microneutralization assay performed independently by the FDA

  7. Screening test for neutralizing antibodies against yellow fever virus, based on a flavivirus pseudotype.

    Directory of Open Access Journals (Sweden)

    Séverine Mercier-Delarue

    Full Text Available Given the possibility of yellow fever virus reintroduction in epidemiologically receptive geographic areas, the risk of vaccine supply disruption is a serious issue. New strategies to reduce the doses of injected vaccines should be evaluated very carefully in terms of immunogenicity. The plaque reduction test for the determination of neutralizing antibodies (PRNT is particularly time-consuming and requires the use of a confinement laboratory. We have developed a new test based on the use of a non-infectious pseudovirus (WN/YF17D. The presence of a reporter gene allows sensitive determination of neutralizing antibodies by flow cytometry. This WN/YF17D test was as sensitive as PRNT for the follow-up of yellow fever vaccinees. Both tests lacked specificity with sera from patients hospitalized for acute Dengue virus infection. Conversely, both assays were strictly negative in adults never exposed to flavivirus infection or vaccination, and in patients sampled some time after acute Dengue infection. This WN/YF17D test will be particularly useful for large epidemiological studies and for screening for neutralizing antibodies against yellow fever virus.

  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. Global panel of HIV-1 Env reference strains for standardized assessments of vaccine-elicited neutralizing antibodies.

    Science.gov (United States)

    deCamp, Allan; Hraber, Peter; Bailer, Robert T; Seaman, Michael S; Ochsenbauer, Christina; Kappes, John; Gottardo, Raphael; Edlefsen, Paul; Self, Steve; Tang, Haili; Greene, Kelli; Gao, Hongmei; Daniell, Xiaoju; Sarzotti-Kelsoe, Marcella; Gorny, Miroslaw K; Zolla-Pazner, Susan; LaBranche, Celia C; Mascola, John R; Korber, Bette T; Montefiori, David C

    2014-03-01

    Standardized assessments of HIV-1 vaccine-elicited neutralizing antibody responses are complicated by the genetic and antigenic variability of the viral envelope glycoproteins (Envs). To address these issues, suitable reference strains are needed that are representative of the global epidemic. Several panels have been recommended previously, but no clear answers have been available on how many and which strains are best suited for this purpose. We used a statistical model selection method to identify a global panel of reference Env clones from among 219 Env-pseudotyped viruses assayed in TZM-bl cells with sera from 205 HIV-1-infected individuals. The Envs and sera were sampled globally from diverse geographic locations and represented all major genetic subtypes and circulating recombinant forms of the virus. Assays with a panel size of only nine viruses adequately represented the spectrum of HIV-1 serum neutralizing activity seen with the larger panel of 219 viruses. An optimal panel of nine viruses was selected and augmented with three additional viruses for greater genetic and antigenic coverage. The spectrum of HIV-1 serum neutralizing activity seen with the final 12-virus panel closely approximated the activity seen with subtype-matched viruses. Moreover, the final panel was highly sensitive for detection of many of the known broadly neutralizing antibodies. For broader assay applications, all 12 Env clones were converted to infectious molecular clones using a proviral backbone carrying a Renilla luciferase reporter gene (Env.IMC.LucR viruses). This global panel should facilitate highly standardized assessments of vaccine-elicited neutralizing antibodies across multiple HIV-1 vaccine platforms in different parts of the world. An effective HIV-1 vaccine will need to overcome the extraordinary genetic variability of the virus, where most variation occurs in the viral envelope glycoproteins that are the sole targets for neutralizing antibodies. Efforts to elicit

  10. A Diverse Panel of Hepatitis C Virus Glycoproteins for Use in Vaccine Research Reveals Extremes of Monoclonal Antibody Neutralization Resistance.

    Science.gov (United States)

    Urbanowicz, Richard A; McClure, C Patrick; Brown, Richard J P; Tsoleridis, Theocharis; Persson, Mats A A; Krey, Thomas; Irving, William L; Ball, Jonathan K; Tarr, Alexander W

    2015-12-23

    Despite significant advances in the treatment of hepatitis C virus (HCV) infection, the need to develop preventative vaccines remains. Identification of the best vaccine candidates and evaluation of their performance in preclinical and clinical development will require appropriate neutralization assays utilizing diverse HCV isolates. We aimed to generate and characterize a panel of HCV E1E2 glycoproteins suitable for subsequent use in vaccine and therapeutic antibody testing. Full-length E1E2 clones were PCR amplified from patient-derived serum samples, cloned into an expression vector, and used to generate viral pseudoparticles (HCVpp). In addition, some of these clones were used to generate cell culture infectious (HCVcc) clones. The infectivity and neutralization sensitivity of these viruses were then determined. Bioinformatic and HCVpp infectivity screening of approximately 900 E1E2 clones resulted in the assembly of a panel of 78 functional E1E2 proteins representing distinct HCV genotypes and different stages of infection. These HCV glycoproteins differed markedly in their sensitivity to neutralizing antibodies. We used this panel to predict antibody efficacy against circulating HCV strains, highlighting the likely reason why some monoclonal antibodies failed in previous clinical trials. This study provides the first objective categorization of cross-genotype patient-derived HCV E1E2 clones according to their sensitivity to antibody neutralization. It has shown that HCV isolates have clearly distinguishable neutralization-sensitive, -resistant, or -intermediate phenotypes, which are independent of genotype. The panel provides a systematic means for characterization of the neutralizing response elicited by candidate vaccines and for defining the therapeutic potential of monoclonal antibodies. Hepatitis C virus (HCV) has a global burden of more than 170 million people, many of whom cannot attain the new, expensive, direct-acting antiviral therapies. A safe and

  11. Analysis of variola and vaccinia virus neutralization assays for smallpox vaccines.

    Science.gov (United States)

    Hughes, Christine M; Newman, Frances K; Davidson, Whitni B; Olson, Victoria A; Smith, Scott K; Holman, Robert C; Yan, Lihan; Frey, Sharon E; Belshe, Robert B; Karem, Kevin L; Damon, Inger K

    2012-07-01

    Possible smallpox reemergence drives research for third-generation vaccines that effectively neutralize variola virus. A comparison of neutralization assays using different substrates, variola and vaccinia (Dryvax and modified vaccinia Ankara [MVA]), showed significantly different 90% neutralization titers; Dryvax underestimated while MVA overestimated variola neutralization. Third-generation vaccines may rely upon neutralization as a correlate of protection.

  12. Inactivated H7 Influenza Virus Vaccines Protect Mice despite Inducing Only Low Levels of Neutralizing Antibodies.

    Science.gov (United States)

    Kamal, Ram P; Blanchfield, Kristy; Belser, Jessica A; Music, Nedzad; Tzeng, Wen-Pin; Holiday, Crystal; Burroughs, Ashley; Sun, Xiangjie; Maines, Taronna R; Levine, Min Z; York, Ian A

    2017-10-15

    Avian influenza viruses of the H7 hemagglutinin (HA) subtype present a significant public health threat, as evidenced by the ongoing outbreak of human A(H7N9) infections in China. When evaluated by hemagglutination inhibition (HI) and microneutralization (MN) assays, H7 viruses and vaccines are found to induce lower level of neutralizing antibodies (nAb) than do their seasonal counterparts, making it difficult to develop and evaluate prepandemic vaccines. We have previously shown that purified recombinant H7 HA appear to be poorly immunogenic in that they induce low levels of HI and MN antibodies. In this study, we immunized mice with whole inactivated reverse genetics reassortant (RG) viruses expressing HA and neuraminidase (NA) from 3 different H7 viruses [A/Shanghai/2/2013(H7N9), A/Netherlands/219/2003(H7N7), and A/New York/107/2003(H7N2)] or with human A(H1N1)pdm09 (A/California/07/2009-like) or A(H3N2) (A/Perth16/2009) viruses. Mice produced equivalent titers of antibodies to all viruses as measured by enzyme-linked immunosorbent assay (ELISA). However, the antibody titers induced by H7 viruses were significantly lower when measured by HI and MN assays. Despite inducing very low levels of nAb, H7 vaccines conferred complete protection against homologous virus challenge in mice, and the serum antibodies directed against the HA head region were capable of mediating protection. The apparently low immunogenicity associated with H7 viruses and vaccines may be at least partly related to measuring antibody titers with the traditional HI and MN assays, which may not provide a true measure of protective immunity associated with H7 immunization. This study underscores the need for development of additional correlates of protection for prepandemic vaccines. IMPORTANCE H7 avian influenza viruses present a serious risk to human health. Preparedness efforts include development of prepandemic vaccines. For seasonal influenza viruses, protection is correlated with antibody

  13. Neutralization Assay for Zika and Dengue Viruses by Use of Real-Time-PCR-Based Endpoint Assessment.

    Science.gov (United States)

    Wilson, Heather L; Tran, Thomas; Druce, Julian; Dupont-Rouzeyrol, Myrielle; Catton, Michael

    2017-10-01

    The global spread and infective complications of Zika virus (ZKV) and dengue virus (DENV) have made them flaviviruses of public health concern. Serological diagnosis can be challenging due to antibody cross-reactivity, particularly in secondary flavivirus infections or when there is a history of flavivirus vaccination. The virus neutralization assay is considered to be the most specific assay for measurement of anti-flavivirus antibodies. This study describes an assay where the neutralization endpoint is measured by real-time PCR, providing results within 72 h. It demonstrated 100% sensitivity (24/24 ZKV and 15/15 DENV) and 100% specificity (11/11 specimens) when testing well-characterized sera. In addition, the assay was able to determine the correct DENV serotype in 91.7% of cases. The high sensitivity and specificity of the real-time PCR neutralization assay makes it suitable to use as a confirmatory test for sera that are reactive in commercial IgM/IgG enzyme immunoassays. Results are objective and the PCR-based measurement of the neutralization endpoint lends itself to automation so that throughput may be increased in times of high demand. Copyright © 2017 American Society for Microbiology.

  14. Development and characterization of neutralizing monoclonal antibodies against canine distemper virus hemagglutinin protein.

    Science.gov (United States)

    Bi, Zhenwei; Xia, Xingxia; Wang, Yongshan; Mei, Yongjie

    2015-04-01

    Canine distemper virus (CDV) causes a serious multisystemic disease in dogs and other carnivora. Hemagglutinin (H) protein-specific antibodies are mainly responsible for protective immunity against CDV infection. In the present study, six neutralizing MAbs to the H protein of CDV were newly obtained and characterized by immunizing BALB/c mice with a recent Chinese field isolate. Competitive binding inhibition assay revealed that they recognized four distinct antigenic regions of the H protein. Immunofluorescence assay and western blotting showed that all MAbs recognize the conformational rather than the linear epitopes of the H protein. Furthermore, in immunofluorescence and virus neutralization assays, two of the MAbs were found to react only with the recent Chinese field isolate and not with older CDV strains, including vaccine strain Onderstepoort, indicating there are neutralization-related antigenic variations between the recent Chinese field isolate and the older CDV strains examined in this study. The newly established MAbs are useful for differentiating the expanding CDV strains and could be used in immunotherapy and immunodiagnosis against infection with CDV. © 2015 The Societies and Wiley Publishing Asia Pty Ltd.

  15. Rapid High-Level Production of Functional HIV Broadly Neutralizing Monoclonal Antibodies in Transient Plant Expression Systems

    Science.gov (United States)

    Rosenberg, Yvonne; Sack, Markus; Montefiori, David; Forthal, Donald; Mao, Lingjun; -Abanto, Segundo Hernandez; Urban, Lori; Landucci, Gary; Fischer, Rainer; Jiang, Xiaoming

    2013-01-01

    Passive immunotherapy using anti-HIV broadly neutralizing monoclonal antibodies (mAbs) has shown promise as an HIV treatment, reducing mother-to-child-transmission (MTCT) of simian/human immunodeficiency virus (SHIV) in non-human primates and decreasing viral rebound in patients who ceased receiving anti-viral drugs. In addition, a cocktail of potent mAbs may be useful as mucosal microbicides and provide an effective therapy for post-exposure prophylaxis. However, even highly neutralizing HIV mAbs used today may lose their effectiveness if resistance occurs, requiring the rapid production of new or engineered mAbs on an ongoing basis in order to counteract the viral resistance or the spread of a certain HIV-1 clade in a particular region or patient. Plant-based expression systems are fast, inexpensive and scalable and are becoming increasingly popular for the production of proteins and monoclonal antibodies. In the present study, Agrobacterium-mediated transient transfection of plants, utilizing two species of Nicotiana, have been tested to rapidly produce high levels of an HIV 89.6PΔ140env and several well-studied anti-HIV neutralizing monoclonal antibodies (b12, 2G12, 2F5, 4E10, m43, VRC01) or a single chain antibody construct (m9), for evaluation in cell-based viral inhibition assays. The protein-A purified plant-derived antibodies were intact, efficiently bound HIV envelope, and were equivalent to, or in one case better than, their counterparts produced in mammalian CHO or HEK-293 cells in both neutralization and antibody dependent viral inhibition assays. These data indicate that transient plant-based transient expression systems are very adaptable and could rapidly generate high levels of newly identified functional recombinant HIV neutralizing antibodies when required. In addition, they warrant detailed cost-benefit analysis of prolonged incubation in plants to further increase mAb production. PMID:23533588

  16. Rapid high-level production of functional HIV broadly neutralizing monoclonal antibodies in transient plant expression systems.

    Directory of Open Access Journals (Sweden)

    Yvonne Rosenberg

    Full Text Available Passive immunotherapy using anti-HIV broadly neutralizing monoclonal antibodies (mAbs has shown promise as an HIV treatment, reducing mother-to-child-transmission (MTCT of simian/human immunodeficiency virus (SHIV in non-human primates and decreasing viral rebound in patients who ceased receiving anti-viral drugs. In addition, a cocktail of potent mAbs may be useful as mucosal microbicides and provide an effective therapy for post-exposure prophylaxis. However, even highly neutralizing HIV mAbs used today may lose their effectiveness if resistance occurs, requiring the rapid production of new or engineered mAbs on an ongoing basis in order to counteract the viral resistance or the spread of a certain HIV-1 clade in a particular region or patient. Plant-based expression systems are fast, inexpensive and scalable and are becoming increasingly popular for the production of proteins and monoclonal antibodies. In the present study, Agrobacterium-mediated transient transfection of plants, utilizing two species of Nicotiana, have been tested to rapidly produce high levels of an HIV 89.6PΔ140env and several well-studied anti-HIV neutralizing monoclonal antibodies (b12, 2G12, 2F5, 4E10, m43, VRC01 or a single chain antibody construct (m9, for evaluation in cell-based viral inhibition assays. The protein-A purified plant-derived antibodies were intact, efficiently bound HIV envelope, and were equivalent to, or in one case better than, their counterparts produced in mammalian CHO or HEK-293 cells in both neutralization and antibody dependent viral inhibition assays. These data indicate that transient plant-based transient expression systems are very adaptable and could rapidly generate high levels of newly identified functional recombinant HIV neutralizing antibodies when required. In addition, they warrant detailed cost-benefit analysis of prolonged incubation in plants to further increase mAb production.

  17. High Concentrations of Measles Neutralizing Antibodies and High-Avidity Measles IgG Accurately Identify Measles Reinfection Cases

    Science.gov (United States)

    Rota, Jennifer S.; Hickman, Carole J.; Mercader, Sara; Redd, Susan; McNall, Rebecca J.; Williams, Nobia; McGrew, Marcia; Walls, M. Laura; Rota, Paul A.; Bellini, William J.

    2016-01-01

    In the United States, approximately 9% of the measles cases reported from 2012 to 2014 occurred in vaccinated individuals. Laboratory confirmation of measles in vaccinated individuals is challenging since IgM assays can give inconclusive results. Although a positive reverse transcription (RT)-PCR assay result from an appropriately timed specimen can provide confirmation, negative results may not rule out a highly suspicious case. Detection of high-avidity measles IgG in serum samples provides laboratory evidence of a past immunologic response to measles from natural infection or immunization. High concentrations of measles neutralizing antibody have been observed by plaque reduction neutralization (PRN) assays among confirmed measles cases with high-avidity IgG, referred to here as reinfection cases (RICs). In this study, we evaluated the utility of measuring levels of measles neutralizing antibody to distinguish RICs from noncases by receiver operating characteristic curve analysis. Single and paired serum samples with high-avidity measles IgG from suspected measles cases submitted to the CDC for routine surveillance were used for the analysis. The RICs were confirmed by a 4-fold rise in PRN titer or by RT-quantitative PCR (RT-qPCR) assay, while the noncases were negative by both assays. Discrimination accuracy was high with serum samples collected ≥3 days after rash onset (area under the curve, 0.953; 95% confidence interval [CI], 0.854 to 0.993). Measles neutralizing antibody concentrations of ≥40,000 mIU/ml identified RICs with 90% sensitivity (95% CI, 74 to 98%) and 100% specificity (95% CI, 82 to 100%). Therefore, when serological or RT-qPCR results are unavailable or inconclusive, suspected measles cases with high-avidity measles IgG can be confirmed as RICs by measles neutralizing antibody concentrations of ≥40,000 mIU/ml. PMID:27335386

  18. SPECT assay of radiolabeled monoclonal antibodies

    International Nuclear Information System (INIS)

    Jaszczak, R.J.

    1992-02-01

    The long-term goal of this research project is to develop methods to improve the utility of single photon emission computed tomography (SPECI) to quantify the biodistribution of monoclonal antibodies (MoAbs) labeled with clinically relevant radionuclides ( 123 I, 131 I, and 111 In) and with another radionuclide, 211 At, recently used in therapy. We describe here our progress in developing quantitative SPECT methodology for 111 In and 123 I. We have focused our recent research thrusts on the following aspects of SPECT: (1) The development of improved SPECT hardware, such as improved acquisition geometries. (2) The development of better reconstruction methods that provide accurate compensation for the physical factors that affect SPECT quantification. (3) The application of carefully designed simulations and experiments to validate our hardware and software approaches

  19. Detection of antibodies against H5 and H7 strains in birds: evaluation of influenza pseudovirus particle neutralization tests

    Directory of Open Access Journals (Sweden)

    Sofie Wallerström

    2014-01-01

    Full Text Available Introduction: Avian influenza viruses circulate in bird populations, and it is important to maintain and uphold our knowledge of the viral strains that are currently of interest in this context. Here, we describe the use of hemagglutinin-pseudotype retroviruses based on highly pathogenic influenza viruses for the screening of avian sera for influenza A antibodies. Our aim was also to determine whether the pseudovirus neutralization tests that we assessed were sensitive and simple to use compared to the traditional methods, including hemagglutination inhibition assays and microneutralization tests. Material and methods: H5 and H7 pseudovirus neutralization tests were evaluated by using serum from infected rabbits. Subsequently, the assays were further investigated using a panel of serum samples from avian species. The panel contained samples that were seropositive for five different hemagglutinin subtypes as well as influenza A seronegative samples. Results and discussion: The results suggest that the pseudovirus neutralization test is an alternative to hemagglutination inhibition assays, as we observed comparable titers to those of both standard microneutralizations assays as well as hemagglutinin inhibition assays. When evaluated by a panel of avian sera, the method also showed its capability to recognize antibodies directed toward low-pathogenic H5 and H7. Hence, we conclude that it is possible to use pseudoviruses based on highly pathogenic avian influenza viruses to screen avian sera for antibodies directed against influenza A subtypes H5 and H7.

  20. Neutralization of White Spot Syndrome Virus by Monoclonal Antibodies against Viral Envelope Proteins

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    Hsiu-Hui Shih

    2004-09-01

    Full Text Available Two monoclonal antibodies (MAbs recognizing envelope proteins of the white spot syndrome virus (WSSV, 6E1 against VP28 and 3E8 against VP19, were applied to demonstrate their neutralizing ability to this virus by using both in vitro and in vivo assays. Mixtures of MAb 6E1 with virus filtrate were inoculated into the primary explant monolayer culture derived from the lymphoid Oka organs of Penaeus monodon. Mab was likely to neutralize the infectivity of virus to monolayer since cytopathic effects were apparently blocked in experiment group. WSSV was titrated using Blue-Cell ELISA and the neutralizing index was calculated to be 6.90 for 6EI and 5.83 for 3E8. Neutralized virus fluids injected intramuscularly into post larvae of P. monodon. The shrimp in the positive control, which were injected with WSSV only showed an increasing mortality and a 100% mortality was reached at day 34, whereas no shrimp died in the negative control. The mortality for 6E1 was 6.7% and for 3E8 was 13.3%. These results suggest that Mabs recognizing the WSSV envelope proteins could neutralize viral infectivity to both cultured cells and shrimp.

  1. Detection of canine distemper virus serum neutralizing antibodies in captive U.S. phocids.

    Science.gov (United States)

    Clancy, Meredith M; Gamble, Kathryn C; Travis, Dominic A

    2013-03-01

    Antibodies to morbilliviruses have been documented in free-ranging pinnipeds throughout populations in the Atlantic and Arctic Oceans, but not from the Pacific Ocean. As a symbolic geographic barrier between the exposed Atlantic and naive Pacific populations, the captive phocid population in North America had undocumented serologic status. In this study, canine distemper virus (CDV) serum neutralization assays were used to assess the prevalence of antibodies in this population with participation of 25 U.S. institutions from grey seals (Halichoerus grypus, n = 6) and harbor seals (Phoca vitulina, n = 108). Historic and environmental risk factors associated with the epidemiology of distemper virus were collected by survey. Based on antibodies to canine distemper virus, the prevalence of exposure in this population was 25.5%, with 28 seals (grey, n = 2; harbor, n = 26) demonstrating antibody titers > or = 1:16, and positive titers ranged from 1:4 to 1:1,536. By survey analysis, strong associations with seropositive status were identified for captive origin (P = 0.013) and movement among institutions (P = 0.024). Size of population has positive correlation with likelihood of seropositive seals at an institution (P = 0.020). However, no major husbandry or enclosure-based risk factors were identified in institutions with seropositive seals, and no interaction between individual or institutional risk factors was identified. Previously undocumented prior to this study, CDV antibodies were measured in harbor seals (n = 2) recently stranded from the Pacific coast.

  2. Delivery of Flightless I Neutralizing Antibody from Porous Silicon Nanoparticles Improves Wound Healing in Diabetic Mice.

    Science.gov (United States)

    Turner, Christopher T; McInnes, Steven J P; Melville, Elizabeth; Cowin, Allison J; Voelcker, Nicolas H

    2017-01-01

    Flightless I (Flii) is elevated in human chronic wounds and is a negative regulator of wound repair. Decreasing its activity improves healing responses. Flii neutralizing antibodies (FnAbs) decrease Flii activity in vivo and hold significant promise as healing agents. However, to avoid the need for repeated application in a clinical setting and to protect the therapeutic antibody from the hostile environment of the wound, suitable delivery vehicles are required. In this study, the use of porous silicon nanoparticles (pSi NPs) is demonstrated for the controlled release of FnAb to diabetic wounds. We achieve FnAb loading regimens exceeding 250 µg antibody per mg of vehicle. FnAb-loaded pSi NPs increase keratinocyte proliferation and enhance migration in scratch wound assays. Release studies confirm the functionality of the FnAb in terms of Flii binding. Using a streptozotocin-induced model of diabetic wound healing, a significant improvement in healing is observed for mice treated with FnAb-loaded pSi NPs compared to controls, including FnAb alone. FnAb-loaded pSi NPs treated with proteases show intact and functional antibody for up to 7 d post-treatment, suggesting protection of the antibodies from proteolytic degradation in wound fluid. pSi NPs may therefore enable new therapeutic approaches for the treatment of diabetic ulcers. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Automated image-based assay for evaluation of HIV neutralization and cell-to-cell fusion inhibition.

    Science.gov (United States)

    Sheik-Khalil, Enas; Bray, Mark-Anthony; Özkaya Şahin, Gülsen; Scarlatti, Gabriella; Jansson, Marianne; Carpenter, Anne E; Fenyö, Eva Maria

    2014-08-30

    Standardized techniques to detect HIV-neutralizing antibody responses are of great importance in the search for an HIV vaccine. Here, we present a high-throughput, high-content automated plaque reduction (APR) assay based on automated microscopy and image analysis that allows evaluation of neutralization and inhibition of cell-cell fusion within the same assay. Neutralization of virus particles is measured as a reduction in the number of fluorescent plaques, and inhibition of cell-cell fusion as a reduction in plaque area. We found neutralization strength to be a significant factor in the ability of virus to form syncytia. Further, we introduce the inhibitory concentration of plaque area reduction (ICpar) as an additional measure of antiviral activity, i.e. fusion inhibition. We present an automated image based high-throughput, high-content HIV plaque reduction assay. This allows, for the first time, simultaneous evaluation of neutralization and inhibition of cell-cell fusion within the same assay, by quantifying the reduction in number of plaques and mean plaque area, respectively. Inhibition of cell-to-cell fusion requires higher quantities of inhibitory reagent than inhibition of virus neutralization.

  4. Induction of neutralizing antibodies by a tobacco chloroplast-derived vaccine based on a B cell epitope from canine parvovirus.

    Science.gov (United States)

    Molina, Andrea; Veramendi, Jon; Hervás-Stubbs, Sandra

    2005-11-25

    The 2L21 epitope of the VP2 protein from the canine parvovirus (CPV), fused to the cholera toxin B subunit (CTB-2L21), was expressed in transgenic tobacco chloroplasts. Mice and rabbits that received protein-enriched leaf extracts by parenteral route produced high titers of anti-2L21 antibodies able to recognize the VP2 protein. Rabbit sera were able to neutralize CPV in an in vitro infection assay with an efficacy similar to the anti-2L21 neutralizing monoclonal antibody 3C9. Anti-2L21 IgG and seric IgA antibodies were elicited when mice were gavaged with a suspension of pulverized tissues from CTB-2L21 transformed plants. Combined immunization (a single parenteral injection followed by oral boosters) shows that oral boosters help to maintain the anti-2L21 IgG response induced after a single injection, whereas parenteral administration of the antigen primes the subsequent oral boosters by promoting the induction of anti-2L21 seric IgA antibodies. Despite the induced humoral response, antibodies elicited by oral delivery did not show neutralizing capacity in the in vitro assay. The high yield of the fusion protein permits the preparation of a high number of vaccine doses from a single plant and makes feasible the oral vaccination using a small amount of crude plant material. However, a big effort has still to be done to enhance the protective efficacy of subunit vaccines by the oral route.

  5. Induction of neutralizing antibodies by a tobacco chloroplast-derived vaccine based on a B cell epitope from canine parvovirus

    International Nuclear Information System (INIS)

    Molina, Andrea; Veramendi, Jon; Hervas-Stubbs, Sandra

    2005-01-01

    The 2L21 epitope of the VP2 protein from the canine parvovirus (CPV), fused to the cholera toxin B subunit (CTB-2L21), was expressed in transgenic tobacco chloroplasts. Mice and rabbits that received protein-enriched leaf extracts by parenteral route produced high titers of anti-2L21 antibodies able to recognize the VP2 protein. Rabbit sera were able to neutralize CPV in an in vitro infection assay with an efficacy similar to the anti-2L21 neutralizing monoclonal antibody 3C9. Anti-2L21 IgG and seric IgA antibodies were elicited when mice were gavaged with a suspension of pulverized tissues from CTB-2L21 transformed plants. Combined immunization (a single parenteral injection followed by oral boosters) shows that oral boosters help to maintain the anti-2L21 IgG response induced after a single injection, whereas parenteral administration of the antigen primes the subsequent oral boosters by promoting the induction of anti-2L21 seric IgA antibodies. Despite the induced humoral response, antibodies elicited by oral delivery did not show neutralizing capacity in the in vitro assay. The high yield of the fusion protein permits the preparation of a high number of vaccine doses from a single plant and makes feasible the oral vaccination using a small amount of crude plant material. However, a big effort has still to be done to enhance the protective efficacy of subunit vaccines by the oral route

  6. Soluble HIV-1 envelope immunogens derived from an elite neutralizer elicit cross-reactive V1V2 antibodies and low potency neutralizing antibodies.

    Directory of Open Access Journals (Sweden)

    Sara Carbonetti

    Full Text Available We evaluated four gp140 Envelope protein vaccine immunogens that were derived from an elite neutralizer, subject VC10042, whose plasma was able to potently neutralize a wide array of genetically distinct HIV-1 isolates. We sought to determine whether soluble Envelope proteins derived from the viruses circulating in VC10042 could be used as immunogens to elicit similar neutralizing antibody responses by vaccination. Each gp140 was tested in its trimeric and monomeric forms, and we evaluated two gp140 trimer vaccine regimens in which adjuvant was supplied at all four immunizations or at only the first two immunizations. Interestingly, all four Envelope immunogens elicited high titers of cross-reactive antibodies that recognize the variable regions V1V2 and are potentially similar to antibodies linked with a reduced risk of HIV-1 acquisition in the RV144 vaccine trial. Two of the four immunogens elicited neutralizing antibody responses that neutralized a wide array of HIV-1 isolates from across genetic clades, but those responses were of very low potency. There were no significant differences in the responses elicited by trimers or monomers, nor was there a significant difference between the two adjuvant regimens. Our study identified two promising Envelope immunogens that elicited anti-V1V2 antibodies and broad, but low potency, neutralizing antibody responses.

  7. Protective levels of canine distemper virus antibody in an urban dog population using plaque reduction neutralization test

    Directory of Open Access Journals (Sweden)

    O.I. Oyedele

    2004-11-01

    Full Text Available Blood samples from 50 dogs were collected at three veterinary clinics in Ibadan and Abuja, Nigeria and the serum from each sample was evaluated serologically for neutralizing antibodies against canine distemper virus (CDV by the highly sensitive plaque reduction (PRN neutralization assay. Thirteen dogs had plaque reduction neutralization titres of 0-100, seven had titres of 100-1 000 while 30 had titres ranging from 1 000-6 000. The PRN titres of vaccinated dogs were found to be significantly higher than unvaccinated dogs. The widespread use of the highly reproducible PRN test for the evaluation of antibody response to CDV may be very important in the generation of international CDV positive serum standards that should help to improve pre-and post-vaccination testing of dogs worldwide.

  8. Co-evolution of a broadly neutralizing HIV-1 antibody and founder virus

    Science.gov (United States)

    Liao, Hua-Xin; Lynch, Rebecca; Zhou, Tongqing; Gao, Feng; Alam, S. Munir; Boyd, Scott D.; Fire, Andrew Z.; Roskin, Krishna M.; Schramm, Chaim A.; Zhang, Zhenhai; Zhu, Jiang; Shapiro, Lawrence; Mullikin, James C.; Gnanakaran, S.; Hraber, Peter; Wiehe, Kevin; Kelsoe, Garnett; Yang, Guang; Xia, Shi-Mao; Montefiori, David C.; Parks, Robert; Lloyd, Krissey E.; Scearce, Richard M.; Soderberg, Kelly A.; Cohen, Myron; Kaminga, Gift; Louder, Mark K.; Tran, Lillan M.; Chen, Yue; Cai, Fangping; Chen, Sheri; Moquin, Stephanie; Du, Xiulian; Joyce, Gordon M.; Srivatsan, Sanjay; Zhang, Baoshan; Zheng, Anqi; Shaw, George M.; Hahn, Beatrice H.; Kepler, Thomas B.; Korber, Bette T.M.; Kwong, Peter D.; Mascola, John R.; Haynes, Barton F.

    2013-01-01

    Current HIV-1 vaccines elicit strain-specific neutralizing antibodies. However, cross-reactive neutralizing antibodies arise in ~20% of HIV-1-infected individuals, and details of their generation could provide a roadmap for effective vaccination. Here we report the isolation, evolution and structure of a broadly neutralizing antibody from an African donor followed from time of infection. The mature antibody, CH103, neutralized ~55% of HIV-1 isolates, and its co-crystal structure with gp120 revealed a novel loop-based mechanism of CD4-binding site recognition. Virus and antibody gene sequencing revealed concomitant virus evolution and antibody maturation. Notably, the CH103-lineage unmutated common ancestor avidly bound the transmitted/founder HIV-1 envelope glycoprotein, and evolution of antibody neutralization breadth was preceded by extensive viral diversification in and near the CH103 epitope. These data elucidate the viral and antibody evolution leading to induction of a lineage of HIV-1 broadly neutralizing antibodies and provide insights into strategies to elicit similar antibodies via vaccination. PMID:23552890

  9. A Three Monoclonal Antibody Combination Potently Neutralizes Multiple Botulinum Neurotoxin Serotype E Subtypes.

    Science.gov (United States)

    Garcia-Rodriguez, Consuelo; Razai, Ali; Geren, Isin N; Lou, Jianlong; Conrad, Fraser; Wen, Wei-Hua; Farr-Jones, Shauna; Smith, Theresa J; Brown, Jennifer L; Skerry, Janet C; Smith, Leonard A; Marks, James D

    2018-03-01

    Human botulism is most commonly caused by botulinum neurotoxin (BoNT) serotypes A, B, and E. For this work, we sought to develop a human monoclonal antibody (mAb)-based antitoxin capable of binding and neutralizing multiple subtypes of BoNT/E. Libraries of yeast-displayed single chain Fv (scFv) antibodies were created from the heavy and light chain variable region genes of humans immunized with pentavalent-toxoid- and BoNT/E-binding scFv isolated by Fluorescence-Activated Cell Sorting (FACS). A total of 10 scFv were isolated that bound one or more BoNT/E subtypes with nanomolar-level equilibrium dissociation constants (K D ). By diversifying the V-regions of the lead mAbs and selecting for cross-reactivity, we generated three scFv that bound all four BoNT/E subtypes tested at three non-overlapping epitopes. The scFvs were converted to IgG that had K D values for the different BoNT/E subtypes ranging from 9.7 nM to 2.28 pM. An equimolar combination of the three mAbs was able to potently neutralize BoNT/E1, BoNT/E3, and BoNT/E4 in a mouse neutralization assay. The mAbs have potential utility as therapeutics and as diagnostics capable of recognizing multiple BoNT/E subtypes. A derivative of the three-antibody combination (NTM-1633) is in pre-clinical development with an investigational new drug (IND) application filing expected in 2018.

  10. A Three Monoclonal Antibody Combination Potently Neutralizes Multiple Botulinum Neurotoxin Serotype E Subtypes

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    Consuelo Garcia-Rodriguez

    2018-03-01

    Full Text Available Human botulism is most commonly caused by botulinum neurotoxin (BoNT serotypes A, B, and E. For this work, we sought to develop a human monoclonal antibody (mAb-based antitoxin capable of binding and neutralizing multiple subtypes of BoNT/E. Libraries of yeast-displayed single chain Fv (scFv antibodies were created from the heavy and light chain variable region genes of humans immunized with pentavalent-toxoid- and BoNT/E-binding scFv isolated by Fluorescence-Activated Cell Sorting (FACS. A total of 10 scFv were isolated that bound one or more BoNT/E subtypes with nanomolar-level equilibrium dissociation constants (KD. By diversifying the V-regions of the lead mAbs and selecting for cross-reactivity, we generated three scFv that bound all four BoNT/E subtypes tested at three non-overlapping epitopes. The scFvs were converted to IgG that had KD values for the different BoNT/E subtypes ranging from 9.7 nM to 2.28 pM. An equimolar combination of the three mAbs was able to potently neutralize BoNT/E1, BoNT/E3, and BoNT/E4 in a mouse neutralization assay. The mAbs have potential utility as therapeutics and as diagnostics capable of recognizing multiple BoNT/E subtypes. A derivative of the three-antibody combination (NTM-1633 is in pre-clinical development with an investigational new drug (IND application filing expected in 2018.

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

    International Nuclear Information System (INIS)

    Spitz, M.; Fossati, C.A.; Schild, G.C.; Spitz, L.; Brasher, M.

    1982-01-01

    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. (Auth.)

  12. 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.

  13. Neutralization of Clostridium difficile Toxin B Mediated by Engineered Lactobacilli That Produce Single-Domain Antibodies

    Science.gov (United States)

    Andersen, Kasper Krogh; Strokappe, Nika M.; Hultberg, Anna; Truusalu, Kai; Smidt, Imbi; Mikelsaar, Raik-Hiio; Mikelsaar, Marika; Verrips, Theo; Hammarström, Lennart

    2015-01-01

    Clostridium difficile is the primary cause of nosocomial antibiotic-associated diarrhea in the Western world. The major virulence factors of C. difficile are two exotoxins, toxin A (TcdA) and toxin B (TcdB), which cause extensive colonic inflammation and epithelial damage manifested by episodes of diarrhea. In this study, we explored the basis for an oral antitoxin strategy based on engineered Lactobacillus strains expressing TcdB-neutralizing antibody fragments in the gastrointestinal tract. Variable domain of heavy chain-only (VHH) antibodies were raised in llamas by immunization with the complete TcdB toxin. Four unique VHH fragments neutralizing TcdB in vitro were isolated. When these VHH fragments were expressed in either secreted or cell wall-anchored form in Lactobacillus paracasei BL23, they were able to neutralize the cytotoxic effect of the toxin in an in vitro cell-based assay. Prophylactic treatment with a combination of two strains of engineered L. paracasei BL23 expressing two neutralizing anti-TcdB VHH fragments (VHH-B2 and VHH-G3) delayed killing in a hamster protection model where the animals were challenged with spores of a TcdA− TcdB+ strain of C. difficile (P survived until the termination of the experiment at day 5 and showed either no damage or limited inflammation of the colonic mucosa despite having been colonized with C. difficile for up to 4 days. The protective effect in the hamster model suggests that the strategy could be explored as a supplement to existing therapies for patients. PMID:26573738

  14. Early low-titer neutralizing antibodies impede HIV-1 replication and select for virus escape.

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    Katharine J Bar

    Full Text Available Single genome sequencing of early HIV-1 genomes provides a sensitive, dynamic assessment of virus evolution and insight into the earliest anti-viral immune responses in vivo. By using this approach, together with deep sequencing, site-directed mutagenesis, antibody adsorptions and virus-entry assays, we found evidence in three subjects of neutralizing antibody (Nab responses as early as 2 weeks post-seroconversion, with Nab titers as low as 1∶20 to 1∶50 (IC(50 selecting for virus escape. In each of the subjects, Nabs targeted different regions of the HIV-1 envelope (Env in a strain-specific, conformationally sensitive manner. In subject CH40, virus escape was first mediated by mutations in the V1 region of the Env, followed by V3. HIV-1 specific monoclonal antibodies from this subject mapped to an immunodominant region at the base of V3 and exhibited neutralizing patterns indistinguishable from polyclonal antibody responses, indicating V1-V3 interactions within the Env trimer. In subject CH77, escape mutations mapped to the V2 region of Env, several of which selected for alterations of glycosylation. And in subject CH58, escape mutations mapped to the Env outer domain. In all three subjects, initial Nab recognition was followed by sequential rounds of virus escape and Nab elicitation, with Nab escape variants exhibiting variable costs to replication fitness. Although delayed in comparison with autologous CD8 T-cell responses, our findings show that Nabs appear earlier in HIV-1 infection than previously recognized, target diverse sites on HIV-1 Env, and impede virus replication at surprisingly low titers. The unexpected in vivo sensitivity of early transmitted/founder virus to Nabs raises the possibility that similarly low concentrations of vaccine-induced Nabs could impair virus acquisition in natural HIV-1 transmission, where the risk of infection is low and the number of viruses responsible for transmission and productive clinical

  15. Neutralizing Activity of Broadly Neutralizing Anti-HIV-1 Antibodies against Clade B Clinical Isolates Produced in Peripheral Blood Mononuclear Cells.

    Science.gov (United States)

    Cohen, Yehuda Z; Lorenzi, Julio C C; Seaman, Michael S; Nogueira, Lilian; Schoofs, Till; Krassnig, Lisa; Butler, Allison; Millard, Katrina; Fitzsimons, Tomas; Daniell, Xiaoju; Dizon, Juan P; Shimeliovich, Irina; Montefiori, David C; Caskey, Marina; Nussenzweig, Michel C

    2018-03-01

    Recently discovered broadly neutralizing antibodies (bNAbs) against HIV-1 demonstrate extensive breadth and potency against diverse HIV-1 strains and represent a promising approach for the treatment and prevention of HIV-1 infection. The breadth and potency of these antibodies have primarily been evaluated by using panels of HIV-1 Env-pseudotyped viruses produced in 293T cells expressing molecularly cloned Env proteins. Here we report on the ability of five bNAbs currently in clinical development to neutralize circulating primary HIV-1 isolates derived from peripheral blood mononuclear cells (PBMCs) and compare the results to those obtained with the pseudovirus panels used to characterize the bNAbs. The five bNAbs demonstrated significantly less breadth and potency against clinical isolates produced in PBMCs than against Env-pseudotyped viruses. The magnitude of this difference in neutralizing activity varied, depending on the antibody epitope. Glycan-targeting antibodies showed differences of only 3- to 4-fold, while antibody 10E8, which targets the membrane-proximal external region, showed a nearly 100-fold decrease in activity between published Env-pseudotyped virus panels and PBMC-derived primary isolates. Utilizing clonal PBMC-derived primary isolates and molecular clones, we determined that the observed discrepancy in bNAb performance is due to the increased sensitivity to neutralization exhibited by 293T-produced Env-pseudotyped viruses. We also found that while full-length molecularly cloned viruses produced in 293T cells exhibit greater sensitivity to neutralization than PBMC-derived viruses do, Env-pseudotyped viruses produced in 293T cells generally exhibit even greater sensitivity to neutralization. As the clinical development of bNAbs progresses, it will be critical to determine the relevance of each of these in vitro neutralization assays to in vivo antibody performance. IMPORTANCE Novel therapeutic and preventive strategies are needed to contain the

  16. Kinetic and HPV infection effects on cross-type neutralizing antibody and avidity responses induced by Cervarix®

    Science.gov (United States)

    Kemp, Troy J.; Safaeian, Mahboobeh; Hildesheim, Allan; Pan, Yuanji; Penrose, Kerri J.; Porras, Carolina; Schiller, John T.; Lowy, Douglas R.; Herrero, Rolando; Pinto, Ligia A.

    2012-01-01

    Background We previously demonstrated that Cervarix® elicits antibody responses against vaccine-related types for which clinical efficacy was demonstrated (HPV-31 and -45). Here, we evaluated the kinetics of neutralization titers and avidity of Cervarix®-induced antibodies up to 36 months of follow-up in unexposed and HPV infected women. Methods A subset of women who participated in the Cost Rica HPV-16/18 Vaccine Trial had pre- and post-vaccination sera tested for antibody responses to HPV-16, -18, -31, -45, and -58 using a pseudovirion-based neutralization assay, and HPV-16 antibody avidity using an HPV-16 L1 VLP (virus-like particle)-based ELISA developed in our laboratory. Results In uninfected women, neutralizing antibody titers did not reach significance until after the 3rd dose for HPV-31 (month 12, p=0.009) and HPV-45 (month 12, p=0.003), but then persisted up to month 36 (HPV-31, p=0.01; HPV-45, p=0.002). Individuals infected with HPV-16 or HPV-31 at enrollment developed a significantly higher median antibody response to the corresponding HPV type after one dose, but there was not a difference between median titers after three doses compared to the HPV negative group. Median HPV-16 antibody avidity and titer increased over time up to month 12; however, the HPV-16 avidity did not correlate well with HPV-16 neutralizing antibody titers at each time point examined, except for month 6. The median avidity levels were higher in HPV-16 infected women at month 1 (p=0.04) and lower in HPV-16 infected women at month 12 (p=0.006) compared to the HPV negative women. Conclusions The persistence of cross-neutralization titers at month 36 suggests cross-reactive antibody responses are likely to persist long-term and are not influenced by infection status at enrollment. However, the weak correlation between avidity and neutralization titers emphasizes the need for examining avidity in efficacy studies to determine if high avidity antibodies play a critical role in

  17. Neutralizing antibody fails to impact the course of Ebola virus infection in monkeys.

    Directory of Open Access Journals (Sweden)

    Wendelien B Oswald

    2007-01-01

    Full Text Available Prophylaxis with high doses of neutralizing antibody typically offers protection against challenge with viruses producing acute infections. In this study, we have investigated the ability of the neutralizing human monoclonal antibody, KZ52, to protect against Ebola virus in rhesus macaques. This antibody was previously shown to fully protect guinea pigs from infection. Four rhesus macaques were given 50 mg/kg of neutralizing human monoclonal antibody KZ52 intravenously 1 d before challenge with 1,000 plaque-forming units of Ebola virus, followed by a second dose of 50 mg/kg antibody 4 d after challenge. A control animal was exposed to virus in the absence of antibody treatment. Passive transfer of the neutralizing human monoclonal antibody not only failed to protect macaques against challenge with Ebola virus but also had a minimal effect on the explosive viral replication following infection. We show that the inability of antibody to impact infection was not due to neutralization escape. It appears that Ebola virus has a mechanism of infection propagation in vivo in macaques that is uniquely insensitive even to high concentrations of neutralizing antibody.

  18. Measurement of neutralizing serum antibodies of patients vaccinated with human papillomavirus L1 or L2-based immunogens using furin-cleaved HPV Pseudovirions.

    Directory of Open Access Journals (Sweden)

    Joshua W Wang

    Full Text Available Antibodies specific for neutralizing epitopes in either Human papillomavirus (HPV capsid protein L1 or L2 can mediate protection from viral challenge and thus their accurate and sensitive measurement at high throughput is likely informative for monitoring response to prophylactic vaccination. Here we compare measurement of L1 and L2-specific neutralizing antibodies in human sera using the standard Pseudovirion-Based Neutralization Assay (L1-PBNA with the newer Furin-Cleaved Pseudovirion-Based Neutralization Assay (FC-PBNA, a modification of the L1-PBNA intended to improve sensitivity towards L2-specific neutralizing antibodies without compromising assay of L1-specific responses. For detection of L1-specific neutralizing antibodies in human sera, the FC- PBNA and L1-PBNA assays showed similar sensitivity and a high level of correlation using WHO standard sera (n = 2, and sera from patients vaccinated with Gardasil (n = 30 or an experimental human papillomavirus type 16 (HPV16 L1 VLP vaccine (n = 70. The detection of L1-specific cross-neutralizing antibodies in these sera using pseudovirions of types phylogenetically-related to those targeted by the L1 virus-like particle (VLP vaccines was also consistent between the two assays. However, for sera from patients (n = 17 vaccinated with an L2-based immunogen (TA-CIN, the FC-PBNA was more sensitive than the L1-PBNA in detecting L2-specific neutralizing antibodies. Further, the neutralizing antibody titers measured with the FC-PBNA correlated with those determined with the L2-PBNA, another modification of the L1-PBNA that spacio-temporally separates primary and secondary receptor engagement, as well as the protective titers measured using passive transfer studies in the murine genital-challenge model. In sum, the FC-PBNA provided sensitive measurement for both L1 VLP and L2-specific neutralizing antibody in human sera. Vaccination with TA-CIN elicits weak cross-protective antibody in a

  19. Myostatin inhibitors in sports drug testing: Detection of myostatin-neutralizing antibodies in plasma/serum by affinity purification and Western blotting.

    Science.gov (United States)

    Walpurgis, Katja; Thomas, Andreas; Schänzer, Wilhelm; Thevis, Mario

    2016-02-01

    Myostatin is a key regulator of skeletal muscle growth and inhibition of its signaling pathway results in an increased muscle mass and function. The aim of this study was to develop a qualitative detection assay for myostatin-neutralizing antibodies for doping control purposes by using immunological approaches. To detect different types of myostatin-neutralizing antibodies irrespective of their amino acid sequence, an immunological assay specific for antibodies directed against myostatin and having a human Fc domain was established. Affinity purification and Western blotting strategies were combined to allow extracting and identifying relevant analytes from 200 μL of plasma/serum in a non-targeted approach. The assay was characterized regarding specificity, linearity, precision, robustness, and recovery. The assay was found to be highly specific, robust, and linear from 0.1 to 1 μg/mL. The precision was successfully specified at three different concentrations and the recovery of the affinity purification was 58%. Within this study, an immunological detection assay for myostatin-neutralizing antibodies present in plasma/serum specimens was developed and successfully characterized. The presented approach can easily be modified to include other therapeutic antibodies and serves as proof-of-concept for the detection of antibody-based myostatin inhibitors in doping control samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. A murine monoclonal antibody based enzyme-linked immunosorbent assay for almond (Prunus dulcis L.) detection.

    Science.gov (United States)

    Su, Mengna; Venkatachalam, Mahesh; Liu, Changqi; Zhang, Ying; Roux, Kenneth H; Sathe, Shridhar K

    2013-11-13

    A sandwich enzyme-linked immunosorbent assay (ELISA) using anti-almond soluble protein rabbit polyclonal antibodies as capture antibodies and murine monoclonal antibody 4C10 as the detection antibodies was developed. The assay is specific and sensitive (3-200 ng almond protein/mL) for almond detection. The standardized assay is accurate (assay variability assay did not register any cross-reactivity with the tested food matrices, suggesting the assay to be almond amandin specific. The assay could detect the presence of declared almond in the tested matched commercial samples. Further, the assay reliably detected the presence of almonds in the laboratory prepared food samples spiked with almond flour.

  1. Development of a blocking ELISA for detection of serum neutralizing antibodies against newly emerged duck Tembusu virus.

    Directory of Open Access Journals (Sweden)

    Xuesong Li

    Full Text Available BACKGROUND: Since April 2010, domesticated ducks in China have been suffering from an emerging infectious disease characterized by retarded growth, high fever, loss of appetite, decline in egg production, and death. The causative agent was identified as a duck Tembusu virus (DTMUV, a member of the Ntaya virus (NTAV group within the genus Flavivirus, family Flaviviridae. DTMUV is highly contagious and spreads rapidly in many species of ducks. More than 10 million shelducks have been infected and approximately 1 million died in 2010. The disease remains a constant threat to the duck industry; however, it is not known whether DTMUV can infect humans or other mammalians, despite the fact that the virus has spread widely in southeast China, one of the most densely populated areas in the world. The lack of reliable methods to detect the serum antibodies against DTMUV has limited our ability to conduct epidemiological investigations in various natural hosts and to evaluate the efficiency of vaccines to DTMUV. METHODOLOGY/PRINCIPAL FINDINGS: A neutralizing monoclonal antibody (mAb 1F5 binding specifically to the E protein was developed. Based on the mAb, a blocking enzyme-linked immunosorbent assay (ELISA was developed for the detection of neutralizing antibodies against DTMUV. The average value of percent inhibition (PI of 350 duck serum samples obtained from DTMUV-free farms was 1.0% ± 5.8% (mean ± SD. The selected cut-off PI values for negative and positive sera were 12.6% (mean +2SD and 18.4% (mean +3SD, respectively. When compared with a serum neutralizing antibody test (SNT using chicken embryonated eggs, the rate of coincidence was 70.6% between the blocking ELISA and SNT, based on the titration of 20 duck DTMUV-positive serum samples. CONCLUSIONS/SIGNIFICANCE: The blocking ELISA based on a neutralizing mAb allowed rapid, sensitive, and specific detection of neutralization-related antibodies against DTMUV.

  2. Reactivity of human sera in a sensitive, high-throughput pseudovirus-based papillomavirus neutralization assay for HPV16 and HPV18

    International Nuclear Information System (INIS)

    Pastrana, Diana V.; Buck, Christopher B.; Pang, Y.-Y. S.; Thompson, Cynthia D.; Castle, Philip E.; FitzGerald, Peter C.; Krueger Kjaer, Susanne; Lowy, Douglas R.; Schiller, John T.

    2004-01-01

    Sensitive high-throughput neutralization assays, based upon pseudoviruses carrying a secreted alkaline phosphatase (SEAP) reporter gene, were developed and validated for human papillomavirus (HPV)16, HPV18, and bovine papillomavirus 1 (BPV1). SEAP pseudoviruses were produced by transient transfection of codon-modified papillomavirus structural genes into an SV40 T antigen expressing line derived from 293 cells, yielding sufficient pseudovirus from one flask for thousands of titrations. In a 96-well plate format, in this initial characterization, the assay was reproducible and appears to be as sensitive as, but more specific than, a standard papillomavirus-like particle (VLP)-based enzyme-linked immunosorbent assay (ELISA). The neutralization assay detected type-specific HPV16 or HPV18 neutralizing antibodies (titers of 160-10240) in sera of the majority of a group of women infected with the corresponding HPV type, but not in virgin women. Sera from HPV16 VLP vaccinees had high anti-HPV16 neutralizing titers (mean: 45000; range: 5120-163840), but no anti-HPV18 neutralizing activity. The SEAP pseudovirus-based neutralization assay should be a practical method for quantifying potentially protective antibody responses in HPV natural history and prophylactic vaccine studies

  3. Prevalence and titers of yellow fever virus neutralizing antibodies in previously vaccinated adults.

    Science.gov (United States)

    Miyaji, Karina Takesaki; Avelino-Silva, Vivian Iida; Simões, Marisol; Freire, Marcos da Silva; Medeiros, Carlos Roberto de; Braga, Patrícia Emilia; Neves, Maria Angélica Acalá; Lopes, Marta Heloisa; Kallas, Esper Georges; Sartori, Ana Marli Christovam

    2017-04-03

    The World Health Organization (WHO) recommends one single dose of the Yellow Fever (YF) vaccine based on studies of antibody persistency in healthy adults. We assessed the prevalence and titers of YF virus neutralizing antibodies in previously vaccinated persons aged  60 years, in comparison to younger adults. We also evaluated the correlation between antibody titers and the time since vaccination among participants who received one vaccine dose, and the seropositivity among participants vaccinated prior to or within the past 10 years. previously vaccinated healthy persons aged  18 years were included. YF virus neutralizing antibody titers were determined by means of the 50% Plaque Reduction Neutralization Test. 46 persons aged  60 years and 48 persons aged 18 to 59 years were enrolled. There was no significant difference in the prevalence of YF virus neutralizing antibodies between the two groups (p = 0.263). However, titers were significantly lower in the elderly (p = 0.022). There was no correlation between YF virus neutralizing antibody titers and the time since vaccination. There was no significant difference in seropositivity among participants vaccinated prior to or within the past 10 years. the clinical relevance of the observed difference in YF virus neutralizing antibody titers between the two groups is not clear.

  4. Neutralization of botulinum neurotoxin by a human monoclonal antibody specific for the catalytic light chain.

    Directory of Open Access Journals (Sweden)

    Sharad P Adekar

    2008-08-01

    Full Text Available Botulinum neurotoxins (BoNT are a family of category A select bioterror agents and the most potent biological toxins known. Cloned antibody therapeutics hold considerable promise as BoNT therapeutics, but the therapeutic utility of antibodies that bind the BoNT light chain domain (LC, a metalloprotease that functions in the cytosol of cholinergic neurons, has not been thoroughly explored.We used an optimized hybridoma method to clone a fully human antibody specific for the LC of serotype A BoNT (BoNT/A. The 4LCA antibody demonstrated potent in vivo neutralization when administered alone and collaborated with an antibody specific for the HC. In Neuro-2a neuroblastoma cells, the 4LCA antibody prevented the cleavage of the BoNT/A proteolytic target, SNAP-25. Unlike an antibody specific for the HC, the 4LCA antibody did not block entry of BoNT/A into cultured cells. Instead, it was taken up into synaptic vesicles along with BoNT/A. The 4LCA antibody also directly inhibited BoNT/A catalytic activity in vitro.An antibody specific for the BoNT/A LC can potently inhibit BoNT/A in vivo and in vitro, using mechanisms not previously associated with BoNT-neutralizing antibodies. Antibodies specific for BoNT LC may be valuable components of an antibody antidote for BoNT exposure.

  5. Respiratory syncytial virus neutralizing antibodies in cord blood, respiratory syncytial virus hospitalization, and recurrent wheeze

    DEFF Research Database (Denmark)

    Stensballe, Lone Graff; Ravn, Henrik; Kristensen, Kim

    2008-01-01

    BACKGROUND: Respiratory syncytial virus (RSV) hospitalization is associated with wheeze. OBJECTIVE: To examine the influence of maternally derived RSV neutralizing antibodies in cord blood on RSV hospitalization and recurrent wheeze in infancy. METHODS: Among children from the Danish National Birth...

  6. Predicting HIV-1 transmission and antibody neutralization efficacy in vivo from stoichiometric parameters.

    Directory of Open Access Journals (Sweden)

    Oliver F Brandenberg

    2017-05-01

    Full Text Available The potential of broadly neutralizing antibodies targeting the HIV-1 envelope trimer to prevent HIV-1 transmission has opened new avenues for therapies and vaccines. However, their implementation remains challenging and would profit from a deepened mechanistic understanding of HIV-antibody interactions and the mucosal transmission process. In this study we experimentally determined stoichiometric parameters of the HIV-1 trimer-antibody interaction, confirming that binding of one antibody is sufficient for trimer neutralization. This defines numerical requirements for HIV-1 virion neutralization and thereby enables mathematical modelling of in vitro and in vivo antibody neutralization efficacy. The model we developed accurately predicts antibody efficacy in animal passive immunization studies and provides estimates for protective mucosal antibody concentrations. Furthermore, we derive estimates of the probability for a single virion to start host infection and the risks of male-to-female HIV-1 transmission per sexual intercourse. Our work thereby delivers comprehensive quantitative insights into both the molecular principles governing HIV-antibody interactions and the initial steps of mucosal HIV-1 transmission. These insights, alongside the underlying, adaptable modelling framework presented here, will be valuable for supporting in silico pre-trial planning and post-hoc evaluation of HIV-1 vaccination or antibody treatment trials.

  7. 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.

  8. Hexon and fiber of adenovirus type 14 and 55 are major targets of neutralizing antibody but only fiber-specific antibody contributes to cross-neutralizing activity.

    Science.gov (United States)

    Feng, Ying; Sun, Xikui; Ye, Xianmiao; Feng, Yupeng; Wang, Jinlin; Zheng, Xuehua; Liu, Xinglong; Yi, Changhua; Hao, Mingli; Wang, Qian; Li, Feng; Xu, Wei; Li, Liang; Li, Chufang; Zhou, Rong; Chen, Ling; Feng, Liqiang

    2018-05-01

    Re-emerging human adenoviruses type 14 (HAdV14) and 55 (HAdV55) represent two highly virulent adenoviruses. The neutralizing antibody (nAb) responses elicited by infection or immunization remain largely unknown. Herein, we generated hexon-chimeric HAdV14 viruses harboring each single or entire hexon hyper-variable-regions (HVR) from HAdV55, and determined the neutralizing epitopes of human and mouse nAbs. In human sera, hexon-targeting nAbs are type-specific and mainly recognize HVR2, 5, and 7. Fiber-targeting nAbs are only detectable in sera cross-neutralizing HAdV14 and HAdV55 and contribute substantially to cross-neutralization. Penton-binding antibodies, however, show no significant neutralizing activities. In mice immunized with HAdV14 or HAdV55, a single immunization mainly elicited hexon-specific nAbs, which recognized HAdV14 HVR1, 2, and 7 and HAdV55 HVR1 and 2, respectively. After a booster immunization, cross-neutralizing fiber-specific nAbs became detectable. These results indicated that hexon elicits type-specific nAbs whereas fiber induces cross-neutralizing nAbs to HAdV14 and HAdV55, which are of significance in vaccine development. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. HIV-1 neutralizing antibodies induced by native-like envelope trimers

    NARCIS (Netherlands)

    Sanders, Rogier W.; van Gils, Marit J.; Derking, Ronald; Sok, Devin; Ketas, Thomas J.; Burger, Judith A.; Ozorowski, Gabriel; Cupo, Albert; Simonich, Cassandra; Goo, Leslie; Arendt, Heather; Kim, Helen J.; Lee, Jeong Hyun; Pugach, Pavel; Williams, Melissa; Debnath, Gargi; Moldt, Brian; van Breemen, Mariëlle J.; Isik, Gözde; Medina-Ramírez, Max; Back, Jaap Willem; Koff, Wayne C.; Julien, Jean-Philippe; Rakasz, Eva G.; Seaman, Michael S.; Guttman, Miklos; Lee, Kelly K.; Klasse, Per Johan; Labranche, Celia; Schief, William R.; Wilson, Ian A.; Overbaugh, Julie; Burton, Dennis R.; Ward, Andrew B.; Montefiori, David C.; Dean, Hansi; Moore, John P.

    2015-01-01

    A challenge for HIV-1 immunogen design is the difficulty of inducing neutralizing antibodies (NAbs) against neutralization-resistant (tier 2) viruses that dominate human transmissions. We show that a soluble recombinant HIV-1 envelope glycoprotein trimer that adopts a native conformation, BG505

  10. Homology of ab1 and ab3 monoclonal antibodies that neutralize Semliki Forest virus

    NARCIS (Netherlands)

    Fernandez, IM; Bos, NA; Harmsen, M; Verheul, AFM; Snippe, H; Kraaijeveld, CA

    2001-01-01

    A noninternal image monoclonal antiidiotypic antibody (ab2 mAb), designated 1,13A321, that had proved its efficacy as vaccine against infection with Semliki Forest virus (SFV) in BALB/c mice, was used as immunogen to generate a panel of SFV-neutralizing monoclonal anti-anti-idiotypic antibodies (ab3

  11. Importance of Neutralizing Monoclonal Antibodies Targeting Multiple Antigenic Sites on the Middle East Respiratory Syndrome Coronavirus Spike Glycoprotein To Avoid Neutralization Escape

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lingshu; Shi, Wei; Chappell, James D.; Joyce, M. Gordon; Zhang, Yi; Kanekiyo, Masaru; Becker, Michelle M.; van Doremalen, Neeltje; Fischer, Robert; Wang, Nianshuang; Corbett, Kizzmekia S.; Choe, Misook; Mason, Rosemarie D.; Van Galen, Joseph G.; Zhou, Tongqing; Saunders, Kevin O.; Tatti, Kathleen M.; Haynes, Lia M.; Kwong, Peter D.; Modjarrad, Kayvon; Kong, Wing-Pui; McLellan, Jason S.; Denison, Mark R.; Munster, Vincent J.; Mascola, John R.; Graham, Barney S.; Gallagher, Tom

    2018-03-07

    ABSTRACT

    Middle East respiratory syndrome coronavirus (MERS-CoV) causes a highly lethal pulmonary infection with ~35% mortality. The potential for a future pandemic originating from animal reservoirs or health care-associated events is a major public health concern. There are no vaccines or therapeutic agents currently available for MERS-CoV. Using a probe-based single B cell cloning strategy, we have identified and characterized multiple neutralizing monoclonal antibodies (MAbs) specifically binding to the receptor-binding domain (RBD) or S1 (non-RBD) regions from a convalescent MERS-CoV-infected patient and from immunized rhesus macaques. RBD-specific MAbs tended to have greater neutralizing potency than non-RBD S1-specific MAbs. Six RBD-specific and five S1-specific MAbs could be sorted into four RBD and three non-RBD distinct binding patterns, based on competition assays, mapping neutralization escape variants, and structural analysis. We determined cocrystal structures for two MAbs targeting the RBD from different angles and show they can bind the RBD only in the “out” position. We then showed that selected RBD-specific, non-RBD S1-specific, and S2-specific MAbs given prophylactically prevented MERS-CoV replication in lungs and protected mice from lethal challenge. Importantly, combining RBD- and non-RBD MAbs delayed the emergence of escape mutations in a cell-based virus escape assay. These studies identify MAbs targeting different antigenic sites on S that will be useful for defining mechanisms of MERS-CoV neutralization and for developing more effective interventions to prevent or treat MERS-CoV infections.

    IMPORTANCEMERS-CoV causes a highly lethal respiratory infection for which no vaccines or antiviral therapeutic options are currently available. Based on continuing exposure from established reservoirs in dromedary camels and bats, transmission of MERS-CoV into humans and future outbreaks are expected. Using

  12. Enzyme-linked immunosorbent assay (ELISA for measles antibody: a comparison with haemagglutination inhibition, immunofluorescence and plaque neutralization tests Reação imunoenzimática (ELISA para detecção de anticorpos para o vírus do sarampo: comparação com reações de inibição da hema-glutinação, imunofluorescência indireta e neutralização de placas

    Directory of Open Access Journals (Sweden)

    Vanda Akico Ueda Fick de Souza

    1991-02-01

    Full Text Available An enzyme-linked immunosorbent assay (ELISA for measles antibodies was compared with Plaque Neutralization (PRN, Haemagglutination inhibition (HI and Fluorescent antibody (IFA tests in 181 sera from vaccinated children and umbilical cord. Of 179 positive samples by the sensitive PRN, only two, with titers of 8, were negative by ELISA (copositivity of 98.9%. IFA and HI presented, respectively, copo-sitivities of 93.3% and 82.7%. The ELISA presented a high sensitivity as well as a good reproducibility and represents an alternative for the time consuming PRN for detection of low measles antibodies.A reação imunoenzimática (ELISA para determinação de anticorpos para o vírus do sarampo foi comparada com a reação de neutralização de placas (RNP, inibição da hemaglutinação (RIH e imunofluorescência indireta (RIF. Das 179 amostras positivas pela RNP, somente 2, com títulos iguais a 8, se apresentaram negativas por ELISA (copositividade de 98.9%. A RIF e RIH apresentaram, respectivamente, copositividade de 93.3 e 82.7%. ELISA apresentou sensibilidade equivalente à complexa RNP, boa reprodutibilidade e representa uma alternativa para a detecção de baixos títulos de anticorpos contra o sarampo.

  13. Sandwich enzyme-linked immunosorbent assay (ELISA) for measuring the concentration of, and detection of antibodies to, Aujeszky's disease virus.

    Science.gov (United States)

    Kardi, V; Szegletes, E; Perényi, T; Pergel, I; Smal, Z

    1990-01-01

    A double antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed for measuring Aujeszky's disease virus (ADV) antigen concentration and an inhibition technique based on the former was developed for detection of antibodies to ADV. The results were checked by determining the cytopathic and serum neutralization titres. The correlation was satisfactory in both cases, with correlation coefficients above 0.8. When measuring ADV antigen concentration, the lower limit of detection was 10(3) TCID 50/0.2 ml. The sensitivity of ELISA in detecting antibodies to ADV was found to be superior to that of the serum neutralization test and, thus, enabled the testing of rabbit and guinea-pig sera.

  14. Characterization of broadly neutralizing antibody responses to HIV-1 in a cohort of long term non-progressors.

    Science.gov (United States)

    González, Nuria; McKee, Krisha; Lynch, Rebecca M; Georgiev, Ivelin S; Jimenez, Laura; Grau, Eulalia; Yuste, Eloísa; Kwong, Peter D; Mascola, John R; Alcamí, José

    2018-01-01

    Only a small fraction of HIV-1-infected patients develop broadly neutralizing antibodies (bNAbs), a process generally associated to chronic antigen stimulation. It has been described that rare aviremic HIV-1-infected patients can generate bNAbs but this issue remains controversial. To address this matter we have assessed bNAb responses in a large cohort of long-term non-progressors (LTNPs) with low or undetectable viremia. Samples from the LTNP cohort of the Spanish AIDS Research Network (87 elite and 42 viremic controllers) and a control population of 176 viremic typical-progressors (TPs) were screened for bNAbs using Env-recombinant viruses. bNAb specificities were studied by ELISA using mutated gp120, neutralization assays with mutated viruses, and peptide competition. Epitope specificities were also elucidated from the serum pattern of neutralization against a panel of diverse HIV-1 isolates. Broadly neutralizing sera were found among 9.3% LTNPs, both elite (7%) and viremic controllers (14%). Within the broadly neutralizing sera, CD4 binding site antibodies were detected by ELISA in 4/12 LTNPs (33%), and 16/33 of TPs (48%). Anti-MPER antibodies were detected in 6/12 LTNPs (50%) and 14/33 TPs (42%) whereas glycan-dependent HIV-1 bNAbs were more frequent in LTNPs (11/12, 92%) as compared to TPs (12/33, 36%). A good concordance between standard serum mapping and neutralization-based mapping was observed. LTNPs, both viremic and elite controllers, showed broad humoral immune responses against HIV-1, including activity against many major epitopes involved in bNAbs-mediated protection.

  15. Differential neutralizing activities of a single domain camelid antibody (VHH specific for ricin toxin's binding subunit (RTB.

    Directory of Open Access Journals (Sweden)

    Cristina Herrera

    Full Text Available Ricin, a member of the A-B family of ribosome-inactivating proteins, is classified as a Select Toxin by the Centers for Disease Control and Prevention because of its potential use as a biothreat agent. In an effort to engineer therapeutics for ricin, we recently produced a collection of alpaca-derived, heavy-chain only antibody VH domains (VHH or "nanobody" specific for ricin's enzymatic (RTA and binding (RTB subunits. We reported that one particular RTB-specific VHH, RTB-B7, when covalently linked via a peptide spacer to different RTA-specific VHHs, resulted in heterodimers like VHH D10/B7 that were capable of passively protecting mice against a lethal dose challenge with ricin. However, RTB-B7 itself, when mixed with ricin at a 1 ∶ 10 toxin:antibody ratio did not afford any protection in vivo, even though it had demonstrable toxin-neutralizing activity in vitro. To better define the specific attributes of antibodies associated with ricin neutralization in vitro and in vivo, we undertook a more thorough characterization of RTB-B7. We report that RTB-B7, even at 100-fold molar excess (toxin:antibody was unable to alter the toxicity of ricin in a mouse model. On the other hand, in two well-established cytotoxicity assays, RTB-B7 neutralized ricin with a 50% inhibitory concentration (IC50 that was equivalent to that of 24B11, a well-characterized and potent RTB-specific murine monoclonal antibody. In fact, RTB-B7 and 24B11 were virtually identical when compared across a series of in vitro assays, including adherence to and neutralization of ricin after the toxin was pre-bound to cell surface receptors. RTB-B7 differed from both 24B11 and VHH D10/B7 in that it was relatively less effective at blocking ricin attachment to receptors on host cells and was not able to form high molecular weight toxin:antibody complexes in solution. Whether either of these activities is important in ricin toxin neutralizing activity in vivo remains to be determined.

  16. 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.

  17. Antibody to gp41 MPER alters functional properties of HIV-1 Env without complete neutralization.

    Directory of Open Access Journals (Sweden)

    Arthur S Kim

    2014-07-01

    Full Text Available Human antibody 10E8 targets the conserved membrane proximal external region (MPER of envelope glycoprotein (Env subunit gp41 and neutralizes HIV-1 with exceptional potency. Remarkably, HIV-1 containing mutations that reportedly knockout 10E8 binding to linear MPER peptides are partially neutralized by 10E8, producing a local plateau in the dose response curve. Here, we found that virus partially neutralized by 10E8 becomes significantly less neutralization sensitive to various MPER antibodies and to soluble CD4 while becoming significantly more sensitive to antibodies and fusion inhibitors against the heptad repeats of gp41. Thus, 10E8 modulates sensitivity of Env to ligands both pre- and post-receptor engagement without complete neutralization. Partial neutralization by 10E8 was influenced at least in part by perturbing Env glycosylation. With unliganded Env, 10E8 bound with lower apparent affinity and lower subunit occupancy to MPER mutant compared to wild type trimers. However, 10E8 decreased functional stability of wild type Env while it had an opposite, stabilizing effect on MPER mutant Envs. Clade C isolates with natural MPER polymorphisms also showed partial neutralization by 10E8 with altered sensitivity to various gp41-targeted ligands. Our findings suggest a novel mechanism of virus neutralization by demonstrating how antibody binding to the base of a trimeric spike cross talks with adjacent subunits to modulate Env structure and function. The ability of an antibody to stabilize, destabilize, partially neutralize as well as alter neutralization sensitivity of a virion spike pre- and post-receptor engagement may have implications for immunotherapy and vaccine design.

  18. Hepatitis C virus epitope exposure and neutralization by antibodies is affected by time and temperature

    DEFF Research Database (Denmark)

    Sabo, Michelle C; Luca, Vincent C; Ray, Stuart C

    2012-01-01

    A recent study with flaviviruses suggested that structural dynamics of the virion impact antibody neutralization via exposure of ostensibly cryptic epitopes. To determine whether this holds true for the distantly related hepatitis C virus (HCV), whose neutralizing epitopes may be obscured...... by a glycan shield, apolipoprotein interactions, and the hypervariable region on the E2 envelope protein, we assessed how time and temperature of pre-incubation altered monoclonal antibody (MAb) neutralization of HCV. Notably, several MAbs showed increased inhibitory activity when pre-binding was performed...

  19. Molecular evolution of broadly neutralizing Llama antibodies to the CD4-binding site of HIV-1.

    Science.gov (United States)

    McCoy, Laura E; Rutten, Lucy; Frampton, Dan; Anderson, Ian; Granger, Luke; Bashford-Rogers, Rachael; Dekkers, Gillian; Strokappe, Nika M; Seaman, Michael S; Koh, Willie; Grippo, Vanina; Kliche, Alexander; Verrips, Theo; Kellam, Paul; Fassati, Ariberto; Weiss, Robin A

    2014-12-01

    To date, no immunization of humans or animals has elicited broadly neutralizing sera able to prevent HIV-1 transmission; however, elicitation of broad and potent heavy chain only antibodies (HCAb) has previously been reported in llamas. In this study, the anti-HIV immune responses in immunized llamas were studied via deep sequencing analysis using broadly neutralizing monoclonal HCAbs as a guides. Distinct neutralizing antibody lineages were identified in each animal, including two defined by novel antibodies (as variable regions called VHH) identified by robotic screening of over 6000 clones. The combined application of five VHH against viruses from clades A, B, C and CRF_AG resulted in neutralization as potent as any of the VHH individually and a predicted 100% coverage with a median IC50 of 0.17 µg/ml for the panel of 60 viruses tested. Molecular analysis of the VHH repertoires of two sets of immunized animals showed that each neutralizing lineage was only observed following immunization, demonstrating that they were elicited de novo. Our results show that immunization can induce potent and broadly neutralizing antibodies in llamas with features similar to human antibodies and provide a framework to analyze the effectiveness of immunization protocols.

  20. Lack of Durable Cross-Neutralizing Antibodies Against Zika Virus from Dengue Virus Infection.

    Science.gov (United States)

    Collins, Matthew H; McGowan, Eileen; Jadi, Ramesh; Young, Ellen; Lopez, Cesar A; Baric, Ralph S; Lazear, Helen M; de Silva, Aravinda M

    2017-05-01

    Cross-reactive antibodies elicited by dengue virus (DENV) infection might affect Zika virus infection and confound serologic tests. Recent data demonstrate neutralization of Zika virus by monoclonal antibodies or human serum collected early after DENV infection. Whether this finding is true in late DENV convalescence (>6 months after infection) is unknown. We studied late convalescent serum samples from persons with prior DENV or Zika virus exposure. Despite extensive cross-reactivity in IgG binding, Zika virus neutralization was not observed among primary DENV infections. We observed low-frequency (23%) Zika virus cross-neutralization in repeat DENV infections. DENV-immune persons who had Zika virus as a secondary infection had distinct populations of antibodies that neutralized DENVs and Zika virus, as shown by DENV-reactive antibody depletion experiments. These data suggest that most DENV infections do not induce durable, high-level Zika virus cross-neutralizing antibodies. Zika virus-specific antibody populations develop after Zika virus infection irrespective of prior DENV immunity.

  1. A rapid one-step radiometric assay for hepatitis B surface antigen utilising monoclonal antibodies

    International Nuclear Information System (INIS)

    Goodall, A.H.; Meek, F.L.; Waters, J.A.; Miescher, G.C.; Janossy, G.; Thomas, H.C.

    1982-01-01

    A two-site antigen assay for HBsAg has been developed that employs 3 monoclonal antibodies. The antibodies were selected for their high affinity and their particular epitope specificity to establish an assay with a sensitivity for the antigen comparable with that of a conventional assay with heterologous antisera. In addition, by selecting a monoclonal antibody for use as a tracer which does not compete for antigenic binding sites with the solid-phase monoclonal antibodies, it has been possible to perform a two-site assay in a single 1 h incubation step, achieving the same degree of sensitivity. This principle of using monoclonal antibodies in a one-step assay therefore gives advantages of speed and simplicity over assays using heterologous antisera and would be applicable to a variety of antigen assays for which appropriate monoclonal antibodies are available. (Auth.)

  2. Mimotopes selected by biopanning with high-titer HIV-neutralizing antibodies in plasma from Chinese slow progressors

    Directory of Open Access Journals (Sweden)

    Xiaoli Zhang

    Full Text Available OBJECTIVE: One approach to identifying HIV-1 vaccine candidates is to dissect the natural antiviral immune response in treatment-naïve individuals infected for over ten years, considered slow progressor patients (SPs. It is suspected that SP plasma has strongly neutralizing antibodies (NAb targeting specific HIV viral epitopes. METHODS: NAbs levels of 11 HIV-1-infected SPs were detected by PBMC-based neutralization assays. To investigate SP NAb epitope, this study used a biopanning approach to obtain mimotopes of HIV-1 that were recognized by SP plasma NAbs. IgG was purified from hightiter NAb SP plasma, and used as the ligand for three rounds of biopanning to select HIV-specific mimotopes from a phage-displayed random peptide library. Double-antibody sandwich ELISA, competitive inhibition assays, and peptide sequence analysis were used to evaluate the characteristics of phage-borne mimotopes. RESULTS: SPs had significantly more plasma neutralizing activity than typical progressors (TPs (p = 0.04. P2 and P9 plasma, which have highest-titer HIV-NAb, were selected as ligands for biopanning. After three rounds of biopanning, 48 phage clones were obtained, of which 22 clones were consistent with requirement, binding with HIV-1 positive plasma and unbinding with HIV-1 negative plasma. Compared with linear HIV-1 protein sequence and HIV-1 protein structure files, only 12 clones were possible linear mimotopes of NAbs. In addition, the C40 clone located in gp41 CHR was found to be a neutralizing epitope, which could inhibit pooled HIV-1 positive plasma reaction. CONCLUSION: Biopanning of serum IgG can yield mimotopes of HIV-1-related antigen epitopes. This methodology provides a basis for exploration into HIV-1-related antigen-antibody interactions and furthers NAb immunotherapy and vaccine design.

  3. Comparison of Six Automated Treponema-Specific Antibody Assays.

    Science.gov (United States)

    Park, Borae G; Yoon, Jihoon G; Rim, John Hoon; Lee, Anna; Kim, Hyon-Suk

    2016-01-01

    Six different Treponema (TP)-specific immunoassays were compared to the fluorescent treponemal antibody absorption (FTA-ABS) test. A total of 615 samples were tested. The overall percent agreement, analytical sensitivity, and analytical specificity of each assay compared to the FTA-ABS test were as follows: Architect Syphilis TP, 99.2%, 96.8%, and 100%; Cobas Syphilis, 99.8%, 99.4%, and 100%; ADVIA Centaur Syphilis, 99.8%, 99.4%, and 100%; HISCL Anti-TP assay kit, 99.7%, 98.7%, and 100%; Immunoticles Auto3 TP, 99.0%, 97.5%, and 99.6%; Mediace TPLA, 98.0%, 98.1%, and 98.0%. All results that were discrepant between the TP-specific assays were associated with samples from noninfectious cases (11 immunoassay false positives and 7 from previous syphilis cases). Our study demonstrated that TP-specific immunoassays generally showed high sensitivities, specificities, and percentages of agreement compared to FTA-ABS, with rare cases of false-positive or false-negative results. Therefore, most TP-specific immunoassays are acceptable for use in screening for syphilis. However, it is important to perform a thorough review of a patient's clinical and treatment history for interpreting the results of syphilis serology. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  4. In vitro neutralization of HCV by goat antibodies against peptides encompassing regions downstream of HVR-1 of E2 glycoprotein.

    Science.gov (United States)

    Tabll, Ashraf A; Atef, Khaled; Bader El Din, Noha G; El Abd, Yasmine S; Salem, Ahmed; Sayed, Ahmed A; Dawood, Reham M; Omran, Moataza H; El-Awady, Mostafa K

    2014-01-01

    This article aims at testing several in vitro systems with various viral sources and cell lines for propagation of HCV to evaluate goat antibodies raised against three E2 epitopes in viral neutralization experiments. Four human cell lines (Huh-7, Huh-7.5, HepG2, and CaCo2) were tested using two different HCV viral sources; Genotype 4 infected sera and J6/JFH HCV cc particles. Neutralization capacity of goat Abs against conserved E2 epitopes; p412 (a.a 412-419), p517 (a.a 517-531), and p430 (a.a 430-447) were examined in the above mentioned in vitro systems. Although infection with patients' sera seems to mimic the in vitro situation, it has limited replication rates as compared with HCV cc particularly in Huh7.5 cells. Non-HCV adapted Huh-7 cells were also found susceptible for transfection with J6/JFH virus but at much slower kinetics. The results of the neutralization assay showed that anti p412 and anti p517 were highly neutralizing to HCVcc. Our data demonstrate that antibodies directed against the viral surface glycoprotein E2 reduced the infectivity of the J6/JFH virus and are promising agents for immunotherapy and HCV vaccine development.

  5. Therapeutic efficacy of antibodies lacking Fcγ receptor binding against lethal dengue virus infection is due to neutralizing potency and blocking of enhancing antibodies [corrected].

    Directory of Open Access Journals (Sweden)

    Katherine L Williams

    2013-02-01

    Full Text Available Dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS are life-threatening complications following infection with one of the four serotypes of dengue virus (DENV. At present, no vaccine or antiviral therapies are available against dengue. Here, we characterized a panel of eight human or mouse-human chimeric monoclonal antibodies (MAbs and their modified variants lacking effector function and dissected the mechanism by which some protect against antibody-enhanced lethal DENV infection. We found that neutralizing modified MAbs that recognize the fusion loop or the A strand epitopes on domains II and III of the envelope protein, respectively, act therapeutically by competing with and/or displacing enhancing antibodies. By analyzing these relationships, we developed a novel in vitro suppression-of-enhancement assay that predicts the ability of modified MAbs to act therapeutically against antibody-enhanced disease in vivo. These studies provide new insight into the biology of DENV pathogenesis and the requirements for antibodies to treat lethal DENV disease.

  6. Neutralizing Antibody Response in Dogs and Cats Inoculated with Commercial Inactivated Rabies Vaccines

    Science.gov (United States)

    SHIRAISHI, Rikiya; NISHIMURA, Masaaki; NAKASHIMA, Ryuji; ENTA, Chiho; HIRAYAMA, Norio

    2013-01-01

    ABSTRACT In Japan, the import quarantine regulation against rabies has required from 2005 that dogs and cats should be inoculated with the rabies vaccine and that the neutralizing antibody titer should be confirmed to be at least 0.5 international units (IU)/ml. The fluorescent antibody virus neutralization (FAVN) test is used as an international standard method for serological testing for rabies. To achieve proper immunization of dogs and cats at the time of import and export, changes in the neutralizing antibody titer after inoculation of the rabies vaccine should be understood in detail. However, few reports have provided this information. In this study, we aimed to determine evaluated, such changes by using sera from experimental dogs and cats inoculated with the rabies vaccine, and we tested samples using the routine FAVN test. In both dogs and cats, proper, regular vaccination enabled the necessary titer of neutralizing antibodies to be maintained in the long term. However, inappropriate timing of blood sampling after vaccination could result in insufficient detected levels of neutralizing antibodies. PMID:24389741

  7. Prevalence of measles neutralizing antibody in children under 15 ...

    African Journals Online (AJOL)

    The immune status of children under 15 years in the Southwestern region of Nigeria against measles virus was determined using the neutralization test with a view to assessing the herd immunity to the virus in these communities. A total of 256 serum samples collected from children were tested by the beta method of ...

  8. Antibodies against Marinobacter algicola and Salmonella typhimurium flagellins do not cross-neutralize TLR5 activation.

    Directory of Open Access Journals (Sweden)

    Raul Terron-Exposito

    Full Text Available Flagellins evoke strong innate and adaptive immune responses. These proteins may play a key role as radioprotectors, exert antitumoral activity in certain types of tumor and reduce graft-versus-host disease in allogeneic hematopoietic stem cell transplant recipients. Notwithstanding, flagellins are highly immunogenic, and repeated use leads to their neutralization by systemic antibodies. This neutralization is not prevented by using functional deleted flagellins. These observations led us to explore the possibility of preventing initial neutralization by means of another functional flagellin that does not belong to common pathogenic bacteria but that has the capacity to activate TLR5. Here we characterized the functional capacity of the two-phase Marinobacter algicola (MA-derived flagellins (F and FR as systemic and mucosal adjuvants and compared their performance with that of Salmonella typhimurium (STF flagellins (FljB and FliC. We also report for the first time on the in vitro and in vivo capacity of various flagellins to trigger TLR5 activation in the presence of species-specific anti-flagellin antibodies, the cross-neutralization mediated by these antibodies, and the sequential use of these flagellins for TLR5 activation. Our results showed that MA flagellins behave in a similar way to STF ones, inducing pro-inflammatory cytokines (IL8, CCL20, CCL2 and evoking a strong in vivo antibody response against a model epitope. More importantly, MA flagellins were fully functional, in vitro or in vivo, in the presence of a high concentration of neutralizing anti-flagellin STF antibodies, and STF flagellin was not inhibited by neutralizing anti-flagellin MA antibodies. The use of active flagellins from distinct bacteria could be a useful approach to prevent systemic neutralization of this group of adjuvants and to facilitate the rational design of flagellin-based vaccines and/or other therapeutic treatments (against ischemia, acute renal failure

  9. Association between HIV-1 coreceptor usage and resistance to broadly neutralizing antibodies.

    Science.gov (United States)

    Pfeifer, Nico; Walter, Hauke; Lengauer, Thomas

    2014-10-01

    Recently discovered broadly neutralizing antibodies have revitalized hopes of developing a universal vaccine against HIV-1. Mainly responsible for new infections are variants only using CCR5 for cell entry, whereas CXCR4-using variants can become dominant in later infection stages. We performed a statistical analysis on two different previously published data sets. The first data set was a panel of 199 diverse HIV-1 isolates for which IC50 neutralization titers were determined for the broadly neutralizing antibodies VRC01, VRC-PG04, PG9, and PG16. The second data set contained env sequences of viral variants extracted from HIV-1-infected humanized mice treated with the antibody PGT128 and from untreated control mice. For the panel of 199 diverse HIV-1 isolates, we found a statistically significant association between viral resistance to PG9 and PG16 and CXCR4 coreceptor usage (P = 0.0011 and P = 0.0010, respectively). Our analysis of viral variants from HIV-1-infected humanized mice under treatment with the broadly neutralizing antibody PGT128 indicated that certain antibodies might drive a viral population toward developing CXCR4 coreceptor usage capability (P = 0.0011 for the comparison between PGT128 and control measurement). These analyses highlight the importance of accounting for a possible coreceptor usage bias pertaining to the effectiveness of an HIV vaccine and to passive antibody transfer as therapeutic approach.

  10. [EIA-IgG antibody measles prevention level estimated from measles neutralizing, particle agglutination and hemagglutination-inhibition antibody titer].

    Science.gov (United States)

    Takayama, Naohide; Saika, Shizuko; Ichinohe, Sadato

    2009-09-01

    Measles hemagglutination inhibition (HI) antibody titer, widely used in clinical practice to simply and easily determine the measles immunity level has, in recent years, been increasingly replaced by measles IgG-antibody titer determined by enzyme-immunoassay (EIA). HI antibody titer appears to reflect this protective level, because HI measures the antibody against H protein required for the measles virus to adhere to host cells. EIA-IgG antibody titer does not correlate with the protective level, similar to particle agglutination (PA) titer, because EIA measures different antibodies, including those unrelated to measles protection. After determining HI, PA, neutralizing test (NT) results, and EIA-IgG antibody titer for individual specimens, we compared EIA-IgG antibody titer obtained using an EIA-Kit (Denka Seiken) to HI, PA, and NT titer with the following results: (1) Subjects with EIA-IgG titer of > or = 12.0 may be protected against measles: (2) Subjects with EIA-IgG titer of 4.0 to 8.0 appear to be protected insufficiently requiring a booster dose against measles: (3) Subjects with EIA-IgG titer of 8.0 to 12.0 may benefit from booster vaccination.

  11. A simple assay for the detection of antibodies to endocrine islet cell surface antigens

    International Nuclear Information System (INIS)

    Contreas, G.; Madsen, O.D.; Vissing, H.; Lernmark, Aa.

    1986-01-01

    A simple and sensitive immunoradiometric assay for the detection of islet cell surface antibodies (CIRMA) has been developed. Live, transformed islet cells derived from a liver metastasis of a transplantable islet cell tumor were grown in removable microtiter wells and incubated with antibody. Cell-bound antibodies were quantitated using 125 I-labelled second antibodies. The assay was used to detect islet cell antibodies present in sera from non-diabetic and diabetic BB rats and proved to be particularly effective for screening hybridoma supernatants in order to identify monoclonal antibodies recognizing islet cell surface antigens. (Auth.)

  12. Antibody-Mediated Neutralization of the Exotoxin Mycolactone, the Main Virulence Factor Produced by Mycobacterium ulcerans.

    Directory of Open Access Journals (Sweden)

    Jean-Pierre Dangy

    2016-06-01

    Full Text Available Mycolactone, the macrolide exotoxin produced by Mycobacterium ulcerans, causes extensive tissue destruction by inducing apoptosis of host cells. In this study, we aimed at the production of antibodies that could neutralize the cytotoxic activities of mycolactone.Using the B cell hybridoma technology, we generated a series of monoclonal antibodies with specificity for mycolactone from spleen cells of mice immunized with the protein conjugate of a truncated synthetic mycolactone derivative. L929 fibroblasts were used as a model system to investigate whether these antibodies can inhibit the biological effects of mycolactone. By measuring the metabolic activity of the fibroblasts, we found that anti-mycolactone mAbs can completely neutralize the cytotoxic activity of mycolactone.The toxin neutralizing capacity of anti-mycolactone mAbs supports the concept of evaluating the macrolide toxin as vaccine target.

  13. Recombinant Sheep Pox Virus Proteins Elicit Neutralizing Antibodies.

    Science.gov (United States)

    Chervyakova, Olga V; Zaitsev, Valentin L; Iskakov, Bulat K; Tailakova, Elmira T; Strochkov, Vitaliy M; Sultankulova, Kulyaisan T; Sandybayev, Nurlan T; Stanbekova, Gulshan E; Beisenov, Daniyar K; Abduraimov, Yergali O; Mambetaliyev, Muratbay; Sansyzbay, Abylay R; Kovalskaya, Natalia Y; Nemchinov, Lev G; Hammond, Rosemarie W

    2016-06-07

    The aim of this work was to evaluate the immunogenicity and neutralizing activity of sheep pox virus (SPPV; genus Capripoxvirus, family Poxviridae) structural proteins as candidate subunit vaccines to control sheep pox disease. SPPV structural proteins were identified by sequence homology with proteins of vaccinia virus (VACV) strain Copenhagen. Four SPPV proteins (SPPV-ORF 060, SPPV-ORF 095, SPPV-ORF 117, and SPPV-ORF 122), orthologs of immunodominant L1, A4, A27, and A33 VACV proteins, respectively, were produced in Escherichia coli. Western blot analysis revealed the antigenic and immunogenic properties of SPPV-060, SPPV-095, SPPV-117 and SPPV-122 proteins when injected with adjuvant into experimental rabbits. Virus-neutralizing activity against SPPV in lamb kidney cell culture was detected for polyclonal antisera raised to SPPV-060, SPPV-117, and SPPV-122 proteins. To our knowledge, this is the first report demonstrating the virus-neutralizing activities of antisera raised to SPPV-060, SPPV-117, and SPPV-122 proteins.

  14. Recombinant Sheep Pox Virus Proteins Elicit Neutralizing Antibodies

    Directory of Open Access Journals (Sweden)

    Olga V. Chervyakova

    2016-06-01

    Full Text Available The aim of this work was to evaluate the immunogenicity and neutralizing activity of sheep pox virus (SPPV; genus Capripoxvirus, family Poxviridae structural proteins as candidate subunit vaccines to control sheep pox disease. SPPV structural proteins were identified by sequence homology with proteins of vaccinia virus (VACV strain Copenhagen. Four SPPV proteins (SPPV-ORF 060, SPPV-ORF 095, SPPV-ORF 117, and SPPV-ORF 122, orthologs of immunodominant L1, A4, A27, and A33 VACV proteins, respectively, were produced in Escherichia coli. Western blot analysis revealed the antigenic and immunogenic properties of SPPV-060, SPPV-095, SPPV-117 and SPPV-122 proteins when injected with adjuvant into experimental rabbits. Virus-neutralizing activity against SPPV in lamb kidney cell culture was detected for polyclonal antisera raised to SPPV-060, SPPV-117, and SPPV-122 proteins. To our knowledge, this is the first report demonstrating the virus-neutralizing activities of antisera raised to SPPV-060, SPPV-117, and SPPV-122 proteins.

  15. Milk from Brazilian women presents secretory IgA antibodies and neutralizes rotavirus G9P[5

    Directory of Open Access Journals (Sweden)

    Simone M.R. Santos

    2013-09-01

    Conclusions: The high correlation between anti-rotavirus antibody levels and neutralizing capacity of the milk samples suggests a possible protective role of these antibodies against infection. These results also support the encouragement of the breast-feeding practice.

  16. Structure of a Human Astrovirus Capsid-Antibody Complex and Mechanistic Insights into Virus Neutralization

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanoff, Walter A.; Campos, Jocelyn; Perez, Edmundo I.; Yin, Lu; Alexander, David L.; DuBois, Rebecca M. (UCSC)

    2016-11-02

    ABSTRACT

    Human astroviruses (HAstVs) are a leading cause of viral diarrhea in young children, the immunocompromised, and the elderly. There are no vaccines or antiviral therapies against HAstV disease. Several lines of evidence point to the presence of protective antibodies in healthy adults as a mechanism governing protection against reinfection by HAstV. However, development of anti-HAstV therapies is hampered by the gap in knowledge of protective antibody epitopes on the HAstV capsid surface. Here, we report the structure of the HAstV capsid spike domain bound to the neutralizing monoclonal antibody PL-2. The antibody uses all six complementarity-determining regions to bind to a quaternary epitope on each side of the dimeric capsid spike. We provide evidence that the HAstV capsid spike is a receptor-binding domain and that the antibody neutralizes HAstV by blocking virus attachment to cells. We identify patches of conserved amino acids that overlap the antibody epitope and may comprise a receptor-binding site. Our studies provide a foundation for the development of therapies to prevent and treat HAstV diarrheal disease.

    IMPORTANCEHuman astroviruses (HAstVs) infect nearly every person in the world during childhood and cause diarrhea, vomiting, and fever. Despite the prevalence of this virus, little is known about how antibodies in healthy adults protect them against reinfection. Here, we determined the crystal structure of a complex of the HAstV capsid protein and a virus-neutralizing antibody. We show that the antibody binds to the outermost spike domain of the capsid, and we provide evidence that the antibody blocks virus attachment to human cells. Importantly, our findings suggest that a subunit-based vaccine focusing the immune system on the HAstV capsid spike domain could be effective in protecting children against HAstV disease.

  17. Mechanistic insights into the neutralization of cytotoxic abrin by the monoclonal antibody D6F10.

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    Shradha Bagaria

    Full Text Available Abrin, an A/B toxin obtained from the Abrus precatorius plant is extremely toxic and a potential bio-warfare agent. Till date there is no antidote or vaccine available against this toxin. The only known neutralizing monoclonal antibody against abrin, namely D6F10, has been shown to rescue the toxicity of abrin in cells as well as in mice. The present study focuses on mapping the epitopic region to understand the mechanism of neutralization of abrin by the antibody D6F10. Truncation and mutational analysis of abrin A chain revealed that the amino acids 74-123 of abrin A chain contain the core epitope and the residues Thr112, Gly114 and Arg118 are crucial for binding of the antibody. In silico analysis of the position of the mapped epitope indicated that it is present close to the active site cleft of abrin A chain. Thus, binding of the antibody near the active site blocks the enzymatic activity of abrin A chain, thereby rescuing inhibition of protein synthesis by the toxin in vitro. At 1∶10 molar concentration of abrin:antibody, the antibody D6F10 rescued cells from abrin-mediated inhibition of protein synthesis but did not prevent cell attachment of abrin. Further, internalization of the antibody bound to abrin was observed in cells by confocal microscopy. This is a novel finding which suggests that the antibody might function intracellularly and possibly explains the rescue of abrin's toxicity by the antibody in whole cells and animals. To our knowledge, this study is the first report on a neutralizing epitope for abrin and provides mechanistic insights into the poorly understood mode of action of anti-A chain antibodies against several toxins including ricin.

  18. Phage Display-Derived Cross-Reactive Neutralizing Antibody against Enterovirus 71 and Coxsackievirus A16.

    Science.gov (United States)

    Zhang, Xiao; Sun, Chunyun; Xiao, Xiangqian; Pang, Lin; Shen, Sisi; Zhang, Jie; Cen, Shan; Yang, Burton B; Huang, Yuming; Sheng, Wang; Zeng, Yi

    2016-01-01

    Enterovirus 71 (EV71) and coxsackievirus A16 (CVA16) are members of the Picornaviridae family and are considered the main causative agents of hand, foot and mouth disease (HFMD). In recent decades large HFMD outbreaks caused by EV71 and CVA16 have become significant public health concerns in the Asia-Pacific region. Vaccines and antiviral drugs are unavailable to prevent EV71 and CVA16 infection. In the current study, a chimeric antibody targeting a highly conserved peptide in the EV71 VP4 protein was isolated by using a phage display technique. The antibody showed cross-neutralizing capability against EV71 and CVA16 in vitro. The results suggest that this phage display-derived antibody will have great potential as a broad neutralizing antibody against EV71 and CVA16 after affinity maturation and humanization.

  19. Neutralizing Antibody Response and Efficacy of Novel Recombinant Tetravalent Dengue DNA Vaccine Comprising Envelope Domain III in Mice

    Directory of Open Access Journals (Sweden)

    Ajit Kulkarni

    2017-03-01

    Full Text Available Background: Dengue is a global arboviral threat to humans; causing 390 million infections per year. The availability of safe and effective tetravalent dengue vaccine is a global requirement to prevent epidemics, morbidity, and mortality associated with it. Methods: Five experimental groups (6 mice per group each of 5-week-old BALB/c mice were immunized with vaccine and placebo (empty plasmid (100 µg, i.m. on days 0, 14 and 28. Among these, four groups (one group per serotype of each were subsequently challenged 3 weeks after the last boost with dengue virus (DENV serotypes 1-4 (100 LD50, 20 µl intracerebrally to determine vaccine efficacy. The fifth group of each was used as a control. The PBS immunized group was used as mock control. Serum samples were collected before and after subsequent immunizations. EDIII fusion protein expression was determined by Western blot. Total protein concentration was measured by Bradford assay. Neutralizing antibodies were assessed by TCID50-CPE inhibition assay. Statistical analysis was performed using Stata/IC 10.1 software for Windows. One-way repeated measures ANOVA and Mann-Whitney test were used for neutralizing antibody analysis and vaccine efficacy, respectively. Results: The recombinant EDIII fusion protein was expressed adequately in transfected 293T cells. Total protein concentration was almost 3 times more than the control. Vaccine candidate induced neutralizing antibodies against all four DENV serotypes with a notable increase after subsequent boosters. Vaccine efficacy was 83.3% (DENV-1, -3, -4 and 50% (DENV-2. Conclusion: Our results suggest that vaccine is immunogenic and protective; however, further studies are required to improve the immunogenicity particularly against DENV-2.

  20. Challenges to the development of vaccines to hepatitis C virus that elicit neutralizing antibodies.

    Directory of Open Access Journals (Sweden)

    Heidi Edelgard Drummer

    2014-07-01

    Full Text Available Despite 20 years of research, a vaccine to prevent hepatitis C virus (HCV infection has not been developed. A vaccine to prevent HCV will need to induce broadly reactive immunity able to prevent infection by the 7 genetically and antigenically distinct genotypes circulating world-wide. Hepatitis C virus encodes two surface exposed glycoproteins, E1 and E2 that function as a heterodimer to mediate viral entry. Neutralizing antibodies (NAbs to both E1 and E2 have been described with the major NAb target being E2. The function of E2 is to attach virions to host cells via cell surface receptors that include, but is not limited to, the tetraspanin CD81 and scavenger receptor B class I. However, E2 has developed a number of immune evasion strategies to limit the effectiveness of the NAb response and possibly limit the ability of the immune system to generate potent NAbs in natural infection. Hypervariable regions that shield the underlying core domain, subdominant neutralization epitopes and glycan shielding combine to make E2 a difficult target for the immune system. This review summarizes recent information on the role of neutralizing antibodies to prevent HCV infection, the targets of the neutralizing antibody response and structural information on glycoprotein E2 in complex with neutralizing antibodies. This new information should provide a framework for the rational design of new vaccine candidates that elicit highly potent broadly reactive NAbs to prevent HCV infection.

  1. Potent neutralizing anti-CD1d antibody reduces lung cytokine release in primate asthma model.

    Science.gov (United States)

    Nambiar, Jonathan; Clarke, Adam W; Shim, Doris; Mabon, David; Tian, Chen; Windloch, Karolina; Buhmann, Chris; Corazon, Beau; Lindgren, Matilda; Pollard, Matthew; Domagala, Teresa; Poulton, Lynn; Doyle, Anthony G

    2015-01-01

    CD1d is a receptor on antigen-presenting cells involved in triggering cell populations, particularly natural killer T (NKT) cells, to release high levels of cytokines. NKT cells are implicated in asthma pathology and blockade of the CD1d/NKT cell pathway may have therapeutic potential. We developed a potent anti-human CD1d antibody (NIB.2) that possesses high affinity for human and cynomolgus macaque CD1d (KD ∼100 pM) and strong neutralizing activity in human primary cell-based assays (IC50 typically <100 pM). By epitope mapping experiments, we showed that NIB.2 binds to CD1d in close proximity to the interface of CD1d and the Type 1 NKT cell receptor β-chain. Together with data showing that NIB.2 inhibited stimulation via CD1d loaded with different glycolipids, this supports a mechanism whereby NIB.2 inhibits NKT cell activation by inhibiting Type 1 NKT cell receptor β-chain interactions with CD1d, independent of the lipid antigen in the CD1d antigen-binding cleft. The strong in vitro potency of NIB.2 was reflected in vivo in an Ascaris suum cynomolgus macaque asthma model. Compared with vehicle control, NIB.2 treatment significantly reduced bronchoalveolar lavage (BAL) levels of Ascaris-induced cytokines IL-5, IL-8 and IL-1 receptor antagonist, and significantly reduced baseline levels of GM-CSF, IL-6, IL-15, IL-12/23p40, MIP-1α, MIP-1β, and VEGF. At a cellular population level NIB.2 also reduced numbers of BAL lymphocytes and macrophages, and blood eosinophils and basophils. We demonstrate that anti-CD1d antibody blockade of the CD1d/NKT pathway modulates inflammatory parameters in vivo in a primate inflammation model, with therapeutic potential for diseases where the local cytokine milieu is critical.

  2. Recombinant Protein Containing B-Cell Epitopes of Different Loxosceles Spider Toxins Generates Neutralizing Antibodies in Immunized Rabbits.

    Science.gov (United States)

    Lima, Sabrina de Almeida; Guerra-Duarte, Clara; Costal-Oliveira, Fernanda; Mendes, Thais Melo; Figueiredo, Luís F M; Oliveira, Daysiane; Machado de Avila, Ricardo A; Ferrer, Valéria Pereira; Trevisan-Silva, Dilza; Veiga, Silvio S; Minozzo, João C; Kalapothakis, Evanguedes; Chávez-Olórtegui, Carlos

    2018-01-01

    Loxoscelism is the most important form of araneism in South America. The treatment of these accidents uses heterologous antivenoms obtained from immunization of production animals with crude loxoscelic venom. Due to the scarcity of this immunogen, new alternatives for its substitution in antivenom production are of medical interest. In the present work, three linear epitopes for Loxosceles astacin-like protease 1 (LALP-1) (SLGRGCTDFGTILHE, ENNTRTIGPFDYDSIMLYGAY, and KLYKCPPVNPYPGGIRPYVNV) and two for hyaluronidase (LiHYAL) (NGGIPQLGDLKAHLEKSAVDI and ILDKSATGLRIIDWEAWR) from Loxosceles intermedia spider venom were identified by SPOT-synthesis technique. One formerly characterized linear epitope (DFSGPYLPSLPTLDA) of sphingomyelinase D (SMase D) SMase-I from Loxosceles laeta was also chosen to constitute a new recombinant multiepitopic protein. These epitopes were combined with a previously produced chimeric multiepitopic protein (rCpLi) composed by linear and conformational B-cell epitopes from SMase D from L. intermedia venom, generating a new recombinant multiepitopic protein derived from loxoscelic toxins (rMEPLox). We demonstrated that rMEPLox is non-toxic and antibodies elicited in rabbits against this antigen present reactivity in ELISA and immunoblot assays with Brazilian L. intermedia, L. laeta, L. gaucho , and L. similis spider venoms. In vivo and in vitro neutralization assays showed that anti-rMEPLox antibodies can efficiently neutralize the sphingomyelinase, hyaluronidase, and metalloproteinase activity of L. intermedia venom. This study suggests that this multiepitopic protein can be a suitable candidate for experimental vaccination approaches or for antivenom production against Loxosceles spp. venoms.

  3. Recombinant Protein Containing B-Cell Epitopes of Different Loxosceles Spider Toxins Generates Neutralizing Antibodies in Immunized Rabbits

    Science.gov (United States)

    Lima, Sabrina de Almeida; Guerra-Duarte, Clara; Costal-Oliveira, Fernanda; Mendes, Thais Melo; Figueiredo, Luís F. M.; Oliveira, Daysiane; Machado de Avila, Ricardo A.; Ferrer, Valéria Pereira; Trevisan-Silva, Dilza; Veiga, Silvio S.; Minozzo, João C.; Kalapothakis, Evanguedes; Chávez-Olórtegui, Carlos

    2018-01-01

    Loxoscelism is the most important form of araneism in South America. The treatment of these accidents uses heterologous antivenoms obtained from immunization of production animals with crude loxoscelic venom. Due to the scarcity of this immunogen, new alternatives for its substitution in antivenom production are of medical interest. In the present work, three linear epitopes for Loxosceles astacin-like protease 1 (LALP-1) (SLGRGCTDFGTILHE, ENNTRTIGPFDYDSIMLYGAY, and KLYKCPPVNPYPGGIRPYVNV) and two for hyaluronidase (LiHYAL) (NGGIPQLGDLKAHLEKSAVDI and ILDKSATGLRIIDWEAWR) from Loxosceles intermedia spider venom were identified by SPOT-synthesis technique. One formerly characterized linear epitope (DFSGPYLPSLPTLDA) of sphingomyelinase D (SMase D) SMase-I from Loxosceles laeta was also chosen to constitute a new recombinant multiepitopic protein. These epitopes were combined with a previously produced chimeric multiepitopic protein (rCpLi) composed by linear and conformational B-cell epitopes from SMase D from L. intermedia venom, generating a new recombinant multiepitopic protein derived from loxoscelic toxins (rMEPLox). We demonstrated that rMEPLox is non-toxic and antibodies elicited in rabbits against this antigen present reactivity in ELISA and immunoblot assays with Brazilian L. intermedia, L. laeta, L. gaucho, and L. similis spider venoms. In vivo and in vitro neutralization assays showed that anti-rMEPLox antibodies can efficiently neutralize the sphingomyelinase, hyaluronidase, and metalloproteinase activity of L. intermedia venom. This study suggests that this multiepitopic protein can be a suitable candidate for experimental vaccination approaches or for antivenom production against Loxosceles spp. venoms. PMID:29666624

  4. MP-4 Contributes to Snake Venom Neutralization by Mucuna pruriens Seeds through an Indirect Antibody-mediated Mechanism*

    Science.gov (United States)

    Kumar, Ashish; Gupta, Chitra; Salunke, Dinakar M.

    2016-01-01

    Mortality due to snakebite is a serious public health problem, and available therapeutics are known to induce debilitating side effects. Traditional medicine suggests that seeds of Mucuna pruriens can provide protection against the effects of snakebite. Our aim is to identify the protein(s) that may be important for snake venom neutralization and elucidate its mechanism of action. To this end, we have identified and purified a protein from M. pruriens, which we have named MP-4. The full-length polypeptide sequence of MP-4 was obtained through N-terminal sequencing of peptide fragments. Sequence analysis suggested that the protein may belong to the Kunitz-type protease inhibitor family and therefore may potentially neutralize the proteases present in snake venom. Using various structural and biochemical tools coupled with in vivo assays, we are able to show that MP-4 does not afford direct protection against snake venom because it is actually a poor inhibitor of serine proteases. Further experiments showed that antibodies generated against MP-4 cross-react with the whole venom and provide protection to mice against Echis carinatus snake venom. This study shows that the MP-4 contributes significantly to the snake venom neutralization activity of M. pruriens seeds through an indirect antibody-mediated mechanism. PMID:26987900

  5. MP-4 Contributes to Snake Venom Neutralization by Mucuna pruriens Seeds through an Indirect Antibody-mediated Mechanism.

    Science.gov (United States)

    Kumar, Ashish; Gupta, Chitra; Nair, Deepak T; Salunke, Dinakar M

    2016-05-20

    Mortality due to snakebite is a serious public health problem, and available therapeutics are known to induce debilitating side effects. Traditional medicine suggests that seeds of Mucuna pruriens can provide protection against the effects of snakebite. Our aim is to identify the protein(s) that may be important for snake venom neutralization and elucidate its mechanism of action. To this end, we have identified and purified a protein from M. pruriens, which we have named MP-4. The full-length polypeptide sequence of MP-4 was obtained through N-terminal sequencing of peptide fragments. Sequence analysis suggested that the protein may belong to the Kunitz-type protease inhibitor family and therefore may potentially neutralize the proteases present in snake venom. Using various structural and biochemical tools coupled with in vivo assays, we are able to show that MP-4 does not afford direct protection against snake venom because it is actually a poor inhibitor of serine proteases. Further experiments showed that antibodies generated against MP-4 cross-react with the whole venom and provide protection to mice against Echis carinatus snake venom. This study shows that the MP-4 contributes significantly to the snake venom neutralization activity of M. pruriens seeds through an indirect antibody-mediated mechanism. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. Evaluation of five hepatitis delta virus marker assays for detection of antigen and antibody.

    OpenAIRE

    Bezeaud, A; Rosenswajg, M; Guillin, M C

    1989-01-01

    Five commercially available assays for hepatitis delta (HD) virus markers were compared for sensitivity, specificity, and reproducibility: three assays for antibody (anti-HD), provided by Diagnostics Pasteur, Organon Teknika, and Abbott Laboratories, and two assays for antigen (HD Ag), from Pasteur and Organon Teknika. The assay from Organon Teknika is the less sensitive assay for anti-HD detection. Although the sensitivities of the Pasteur and Abbott assays for anti-HD detection are similar,...

  7. Enhanced neutralization potency of botulinum neurotoxin antibodies using a red blood cell-targeting fusion protein.

    Directory of Open Access Journals (Sweden)

    Sharad P Adekar

    2011-03-01

    Full Text Available Botulinum neurotoxin (BoNT potently inhibits cholinergic signaling at the neuromuscular junction. The ideal countermeasures for BoNT exposure are monoclonal antibodies or BoNT antisera, which form BoNT-containing immune complexes that are rapidly cleared from the general circulation. Clearance of opsonized toxins may involve complement receptor-mediated immunoadherence to red blood cells (RBC in primates or to platelets in rodents. Methods of enhancing immunoadherence of BoNT-specific antibodies may increase their potency in vivo. We designed a novel fusion protein (FP to link biotinylated molecules to glycophorin A (GPA on the RBC surface. The FP consists of an scFv specific for murine GPA fused to streptavidin. FP:mAb:BoNT complexes bound specifically to the RBC surface in vitro. In a mouse model of BoNT neutralization, the FP increased the potency of single and double antibody combinations in BoNT neutralization. A combination of two antibodies with the FP gave complete neutralization of 5,000 LD50 BoNT in mice. Neutralization in vivo was dependent on biotinylation of both antibodies and correlated with a reduction of plasma BoNT levels. In a post-exposure model of intoxication, FP:mAb complexes gave complete protection from a lethal BoNT/A1 dose when administered within 2 hours of toxin exposure. In a pre-exposure prophylaxis model, mice were fully protected for 72 hours following administration of the FP:mAb complex. These results demonstrate that RBC-targeted immunoadherence through the FP is a potent enhancer of BoNT neutralization by antibodies in vivo.

  8. Engineering Venom’s Toxin-Neutralizing Antibody Fragments and Its Therapeutic Potential

    Directory of Open Access Journals (Sweden)

    Larissa M. Alvarenga

    2014-08-01

    Full Text Available Serum therapy remains the only specific treatment against envenoming, but anti-venoms are still prepared by fragmentation of polyclonal antibodies isolated from hyper-immunized horse serum. Most of these anti-venoms are considered to be efficient, but their production is tedious, and their use may be associated with adverse effects. Recombinant antibodies and smaller functional units are now emerging as credible alternatives and constitute a source of still unexploited biomolecules capable of neutralizing venoms. This review will be a walk through the technologies that have recently been applied leading to novel antibody formats with better properties in terms of homogeneity, specific activity and possible safety.

  9. Interplay of foot-and-mouth disease virus, antibodies and plasmacytoid dendritic cells: virus opsonization under non-neutralizing conditions results in enhanced interferon-alpha responses

    Directory of Open Access Journals (Sweden)

    Lannes Nils

    2012-08-01

    Full Text Available Abstract Foot-and-mouth disease virus (FMDV is a highly infectious member of the Picornaviridae inducing an acute disease of cloven-hoofed species. Vaccine-induced immune protection correlates with the presence of high levels of neutralizing antibodies but also opsonising antibodies have been proposed as an important mechanism of the immune response contributing to virus clearance by macrophages and leading to the production of type-I interferon (IFN by plasmacytoid dendritic cells (pDC. The present study demonstrates that the opsonising antibody titres mediating enhanced IFN-α responses in pDC were similar to neutralizing titres, when antigenically related viruses from the same serotype were employed. However, sera cross-reacted also with non-neutralized isolates of multiple serotypes, when tested in this assay. Both uncomplexed virus and immune complexed virus stimulated pDC via Toll-like receptor 7. An additional finding of potential importance for strain-specific differences in virulence and/or immunogenicity was that pDC activation by FMDV strongly differed between viral isolates. Altogether, our results indicate that opsonising antibodies can have a broader reactivity than neutralizing antibodies and may contribute to antiviral responses induced against antigenically distant viruses.

  10. Comprehensive analysis of sperm DNA fragmentation by five different assays: TUNEL assay, SCSA, SCD test and alkaline and neutral Comet assay.

    Science.gov (United States)

    Ribas-Maynou, J; García-Peiró, A; Fernández-Encinas, A; Abad, C; Amengual, M J; Prada, E; Navarro, J; Benet, J

    2013-09-01

    Sperm DNA fragmentation (SDF) is becoming an important test to assess male infertility. Several different tests are available, but no consensus has yet been reached as to which tests are most predictive of infertility. Few publications have reported a comprehensive analysis comparing these methods within the same population. The objective of this study was to analyze the differences between the five most common methodologies, to study their correlations and to establish their cut-off values, sensitivity and specificity in predicting male infertility. We found differences in SDF between fertile donors and infertile patients in TUNEL, SCSA, SCD and alkaline Comet assays, but none with the neutral Comet assay. The alkaline COMET assay was the best in predicting male infertility followed by TUNEL, SCD and SCSA, whereas the neutral COMET assay had no predictive power. For our patient population, threshold values for infertility were 20.05% for TUNEL assay, 18.90% for SCSA, 22.75% for the SCD test, 45.37% for alkaline Comet and 34.37% for neutral Comet. This work establishes in a comprehensive study that the all techniques except neutral Comet are useful to distinguish fertile and infertile men. © 2013 American Society of Andrology and European Academy of Andrology.

  11. Modeling neutralization kinetics of HIV by broadly neutralizing monoclonal antibodies in genital secretions coating the cervicovaginal mucosa.

    Directory of Open Access Journals (Sweden)

    Scott A McKinley

    Full Text Available Eliciting broadly neutralizing antibodies (bnAb in cervicovaginal mucus (CVM represents a promising "first line of defense" strategy to reduce vaginal HIV transmission. However, it remains unclear what levels of bnAb must be present in CVM to effectively reduce infection. We approached this complex question by modeling the dynamic tally of bnAb coverage on HIV. This analysis introduces a critical, timescale-dependent competition: to protect, bnAb must accumulate at sufficient stoichiometry to neutralize HIV faster than virions penetrate CVM and reach target cells. We developed a model that incorporates concentrations and diffusivities of HIV and bnAb in semen and CVM, kinetic rates for binding (kon and unbinding (koff of select bnAb, and physiologically relevant thicknesses of CVM and semen layers. Comprehensive model simulations lead to robust conclusions about neutralization kinetics in CVM. First, due to the limited time virions in semen need to penetrate CVM, substantially greater bnAb concentrations than in vitro estimates must be present in CVM to neutralize HIV. Second, the model predicts that bnAb with more rapid kon, almost independent of koff, should offer greater neutralization potency in vivo. These findings suggest the fastest arriving virions at target cells present the greatest likelihood of infection. It also implies the marked improvements in in vitro neutralization potency of many recently discovered bnAb may not translate to comparable reduction in the bnAb dose needed to confer protection against initial vaginal infections. Our modeling framework offers a valuable tool to gaining quantitative insights into the dynamics of mucosal immunity against HIV and other infectious diseases.

  12. Modeling neutralization kinetics of HIV by broadly neutralizing monoclonal antibodies in genital secretions coating the cervicovaginal mucosa.

    Science.gov (United States)

    McKinley, Scott A; Chen, Alex; Shi, Feng; Wang, Simi; Mucha, Peter J; Forest, M Gregory; Lai, Samuel K

    2014-01-01

    Eliciting broadly neutralizing antibodies (bnAb) in cervicovaginal mucus (CVM) represents a promising "first line of defense" strategy to reduce vaginal HIV transmission. However, it remains unclear what levels of bnAb must be present in CVM to effectively reduce infection. We approached this complex question by modeling the dynamic tally of bnAb coverage on HIV. This analysis introduces a critical, timescale-dependent competition: to protect, bnAb must accumulate at sufficient stoichiometry to neutralize HIV faster than virions penetrate CVM and reach target cells. We developed a model that incorporates concentrations and diffusivities of HIV and bnAb in semen and CVM, kinetic rates for binding (kon) and unbinding (koff) of select bnAb, and physiologically relevant thicknesses of CVM and semen layers. Comprehensive model simulations lead to robust conclusions about neutralization kinetics in CVM. First, due to the limited time virions in semen need to penetrate CVM, substantially greater bnAb concentrations than in vitro estimates must be present in CVM to neutralize HIV. Second, the model predicts that bnAb with more rapid kon, almost independent of koff, should offer greater neutralization potency in vivo. These findings suggest the fastest arriving virions at target cells present the greatest likelihood of infection. It also implies the marked improvements in in vitro neutralization potency of many recently discovered bnAb may not translate to comparable reduction in the bnAb dose needed to confer protection against initial vaginal infections. Our modeling framework offers a valuable tool to gaining quantitative insights into the dynamics of mucosal immunity against HIV and other infectious diseases.

  13. 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...

  14. MERS Coronavirus Neutralizing Antibodies in Camels, Eastern Africa, 1983-1997

    NARCIS (Netherlands)

    Müller, Marcel A; Corman, Victor Max; Jores, Joerg; Meyer, Benjamin; Younan, Mario; Liljander, Anne; Bosch, Berend-Jan; Lattwein, Erik; Hilali, Mosaad; Musa, Bakri E; Bornstein, Set; Drosten, Christian

    2014-01-01

    To analyze the distribution of Middle East respiratory syndrome coronavirus (MERS-CoV)-seropositive dromedary camels in eastern Africa, we tested 189 archived serum samples accumulated during the past 30 years. We identified MERS-CoV neutralizing antibodies in 81.0% of samples from the main

  15. Interplay of HIV-1 phenotype and neutralizing antibody response in pathogenesis of AIDS.

    Science.gov (United States)

    Scarlatti, G; Leitner, T; Hodara, V; Jansson, M; Karlsson, A; Wahlberg, J; Rossi, P; Uhlén, M; Fenyö, E M; Albert, J

    1996-06-01

    A majority of human immunodeficiency virus type 1 (HIV-1) infected individuals display a rapid loss of CD4+ lymphocytes with fast progression towards overt acquired immunodeficiency syndrome (AIDS). However, a small proportion of individuals infected by HIV-1 remain immunologically intact for many years. In order to identify factors that might influence the pathogenesis of HIV-1 infection, 21 Italian mothers and 11 Swedish homosexual men were studied for the presence of autologous neutralizing antibodies in serum, biological phenotype of virus isolates and envelope variable region 3 (V3) sequences. The results were compared to the risk of mother-to-child transmission and progression of the disease. The presence of a neutralizing antibody response to the autologous virus as well as a virus with slow replicative capacity were linked both to low risk of mother-to-child transmission and non-progression of the disease. Patients whose peripheral blood mononuclear cells contained a mutation in the tip of the V3 loop (Arg318 to serine, lysine or leucine) significantly more often had neutralizing antibodies to autologous virus isolates containing arginine at this position. Thus, it appears that the interplay and balance between neutralizing antibody response of the host and the biological phenotype of HIV-1 strongly influence pathogenesis.

  16. HIV-specific Fc effector function early in infection predicts the development of broadly neutralizing antibodies.

    Directory of Open Access Journals (Sweden)

    Simone I Richardson

    2018-04-01

    Full Text Available While the induction of broadly neutralizing antibodies (bNAbs is a major goal of HIV vaccination strategies, there is mounting evidence to suggest that antibodies with Fc effector function also contribute to protection against HIV infection. Here we investigated Fc effector functionality of HIV-specific IgG plasma antibodies over 3 years of infection in 23 individuals, 13 of whom developed bNAbs. Antibody-dependent cellular phagocytosis (ADCP, complement deposition (ADCD, cellular cytotoxicity (ADCC and cellular trogocytosis (ADCT were detected in almost all individuals with levels of activity increasing over time. At 6 months post-infection, individuals with bNAbs had significantly higher levels of ADCD and ADCT that correlated with antibody binding to C1q and FcγRIIa respectively. In addition, antibodies from individuals with bNAbs showed more IgG subclass diversity to multiple HIV antigens which also correlated with Fc polyfunctionality. Germinal center activity represented by CXCL13 levels and expression of activation-induced cytidine deaminase (AID was found to be associated with neutralization breadth, Fc polyfunctionality and IgG subclass diversity. Overall, multivariate analysis by random forest classification was able to group bNAb individuals with 85% sensitivity and 80% specificity based on the properties of their antibody Fc early in HIV infection. Thus, the Fc effector function profile predicted the development of neutralization breadth in this cohort, suggesting that intrinsic immune factors within the germinal center provide a mechanistic link between the Fc and Fab of HIV-specific antibodies.

  17. HIV-specific Fc effector function early in infection predicts the development of broadly neutralizing antibodies.

    Science.gov (United States)

    Richardson, Simone I; Chung, Amy W; Natarajan, Harini; Mabvakure, Batsirai; Mkhize, Nonhlanhla N; Garrett, Nigel; Abdool Karim, Salim; Moore, Penny L; Ackerman, Margaret E; Alter, Galit; Morris, Lynn

    2018-04-01

    While the induction of broadly neutralizing antibodies (bNAbs) is a major goal of HIV vaccination strategies, there is mounting evidence to suggest that antibodies with Fc effector function also contribute to protection against HIV infection. Here we investigated Fc effector functionality of HIV-specific IgG plasma antibodies over 3 years of infection in 23 individuals, 13 of whom developed bNAbs. Antibody-dependent cellular phagocytosis (ADCP), complement deposition (ADCD), cellular cytotoxicity (ADCC) and cellular trogocytosis (ADCT) were detected in almost all individuals with levels of activity increasing over time. At 6 months post-infection, individuals with bNAbs had significantly higher levels of ADCD and ADCT that correlated with antibody binding to C1q and FcγRIIa respectively. In addition, antibodies from individuals with bNAbs showed more IgG subclass diversity to multiple HIV antigens which also correlated with Fc polyfunctionality. Germinal center activity represented by CXCL13 levels and expression of activation-induced cytidine deaminase (AID) was found to be associated with neutralization breadth, Fc polyfunctionality and IgG subclass diversity. Overall, multivariate analysis by random forest classification was able to group bNAb individuals with 85% sensitivity and 80% specificity based on the properties of their antibody Fc early in HIV infection. Thus, the Fc effector function profile predicted the development of neutralization breadth in this cohort, suggesting that intrinsic immune factors within the germinal center provide a mechanistic link between the Fc and Fab of HIV-specific antibodies.

  18. Measles Virus Hemagglutinin epitopes immunogenic in natural infection and vaccination are targeted by broad or genotype-specific neutralizing monoclonal antibodies.

    Science.gov (United States)

    Muñoz-Alía, Miguel Angel; Casasnovas, José M; Celma, María Luisa; Carabaña, Juan; Liton, Paloma B; Fernandez-Muñoz, Rafael

    2017-05-15

    Measles virus (MV) remains a leading cause of vaccine-preventable deaths in children. Protection against MV is associated with neutralizing antibodies that preferentially recognize the viral hemagglutinin (MV-H), and to a lesser extent, the fusion protein (MV-F). Although MV is serologically monotypic, 24 genotypes have been identified. Here we report three neutralization epitopes conserved in the more prevalent circulating MV genotypes, two located in the MV-H receptor binding site (RBS) (antigenic site III) and a third in MV-H/MV-F interphase (antigenic site Ia) which are essential for MV multiplication. In contrast, two MV-H neutralization epitopes, showed a genotype-specific neutralization escape due to a single amino acid change, that we mapped in the "noose" antigenic site, or an enhanced neutralization epitope (antigenic site IIa). The monoclonal antibody (mAb) neutralization potency correlated with its binding affinity and was mainly driven by kinetic dissociation rate (k off ). We developed an immunoassay for mAb binding to MV-H in its native hetero-oligomeric structure with MV-F on the surface of a MV productive steady-state persistently infected (p.i.) human cell lines, and a competitive-binding assay with serum from individuals with past infection by different MV genotypes. Binding assays revealed that a broad neutralization epitope, in RBS antigenic site, a genotype specific neutralization epitopes, in noose and IIa sites, were immunogenic in natural infection and vaccination and may elicit long-lasting humoral immunity that might contribute to explain MV immunogenic stability. These results support the design of improved measles vaccines, broad-spectrum prophylactic or therapeutic antibodies and MV-used in oncolytic therapies. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Antibody-mediated neutralization of Ebola virus can occur by two distinct mechanisms

    International Nuclear Information System (INIS)

    Shedlock, Devon J.; Bailey, Michael A.; Popernack, Paul M.; Cunningham, James M.; Burton, Dennis R.; Sullivan, Nancy J.

    2010-01-01

    Human Ebola virus causes severe hemorrhagic fever disease with high mortality and there is no vaccine or treatment. Antibodies in survivors occur early, are sustained, and can delay infection when transferred into nonhuman primates. Monoclonal antibodies (mAbs) from survivors exhibit potent neutralizing activity in vitro and are protective in rodents. To better understand targets and mechanisms of neutralization, we investigated a panel of mAbs shown previously to react with the envelope glycoprotein (GP). While one non-neutralizing mAb recognized a GP epitope in the nonessential mucin-like domain, the rest were specific for GP1, were neutralizing, and could be further distinguished by reactivity with secreted GP. We show that survivor antibodies, human KZ52 and monkey JP3K11, were specific for conformation-dependent epitopes comprising residues in GP1 and GP2 and that neutralization occurred by two distinct mechanisms; KZ52 inhibited cathepsin cleavage of GP whereas JP3K11 recognized the cleaved, fusion-active form of GP.

  20. Development and characterization of novel chimeric monoclonal antibodies for broad spectrum neutralization of rabies virus.

    Directory of Open Access Journals (Sweden)

    Pan Kyeom Kim

    Full Text Available Current post-exposure prophylaxis for rabies virus infection has several limitations in terms of supply, cost, safety, and efficacy. Attempts to replace human or equine rabies immune globulins (HRIG or ERIG have been made by several companies and institutes. We developed potent monoclonal antibodies to neutralize a broad spectrum of rabies viruses by screening hybridomas received from the U.S. Centers for Disease Control and Prevention (CDC. Two kinds of chimeric human antibodies (chimeric #7 and #17 were constructed by cloning the variable regions from selected hybridomas and the constant region of a human antibody. Two antibodies were bound to antigenic site III and I/IV, respectively, and were able to neutralize 51 field isolates of rabies virus that were isolated at different times and places such as Asia, Africa, North America, South America, and Australia. These two antibodies neutralize rabies viruses with high efficacy in an in vivo test using Syrian hamster and mouse models and show low risk for adverse immunogenicity.

  1. Development and characterization of novel chimeric monoclonal antibodies for broad spectrum neutralization of rabies virus.

    Science.gov (United States)

    Kim, Pan Kyeom; Keum, Sun Ju; Osinubi, Modupe O V; Franka, Richard; Shin, Ji Young; Park, Sang Tae; Kim, Man Su; Park, Mi Jung; Lee, Soo Young; Carson, William; Greenberg, Lauren; Yu, Pengcheng; Tao, Xiaoyan; Lihua, Wang; Tang, Qing; Liang, Guodong; Shampur, Madhusdana; Rupprecht, Charles E; Chang, Shin Jae

    2017-01-01

    Current post-exposure prophylaxis for rabies virus infection has several limitations in terms of supply, cost, safety, and efficacy. Attempts to replace human or equine rabies immune globulins (HRIG or ERIG) have been made by several companies and institutes. We developed potent monoclonal antibodies to neutralize a broad spectrum of rabies viruses by screening hybridomas received from the U.S. Centers for Disease Control and Prevention (CDC). Two kinds of chimeric human antibodies (chimeric #7 and #17) were constructed by cloning the variable regions from selected hybridomas and the constant region of a human antibody. Two antibodies were bound to antigenic site III and I/IV, respectively, and were able to neutralize 51 field isolates of rabies virus that were isolated at different times and places such as Asia, Africa, North America, South America, and Australia. These two antibodies neutralize rabies viruses with high efficacy in an in vivo test using Syrian hamster and mouse models and show low risk for adverse immunogenicity.

  2. Structural Basis for Escape of Human Astrovirus from Antibody Neutralization: Broad Implications for Rational Vaccine Design

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanoff, Walter A.; Perez, Edmundo I.; López, Tomás; Arias, Carlos F.; DuBois, Rebecca M. (UNAM-Mexico); (UCSC)

    2017-10-25

    ABSTRACT

    Human astroviruses are recognized as a leading cause of viral diarrhea worldwide in children, immunocompromised patients, and the elderly. There are currently no vaccines available to prevent astrovirus infection; however, antibodies developed by healthy individuals during previous infection correlate with protection from reinfection, suggesting that an effective vaccine could be developed. In this study, we investigated the molecular mechanism by which several strains of human astrovirus serotype 2 (HAstV-2) are resistant to the potent HAstV-2-neutralizing monoclonal antibody PL-2 (MAb PL-2). Sequencing of the HAstV-2 capsid genes reveals mutations in the PL-2 epitope within the capsid's spike domain. To understand the molecular basis for resistance from MAb PL-2 neutralization, we determined the 1.35-Å-resolution crystal structure of the capsid spike from one of these HAstV-2 strains. Our structure reveals a dramatic conformational change in a loop within the PL-2 epitope due to a serine-to-proline mutation, locking the loop in a conformation that sterically blocks binding and neutralization by MAb PL-2. We show that mutation to serine permits loop flexibility and recovers MAb PL-2 binding. Importantly, we find that HAstV-2 capsid spike containing a serine in this loop is immunogenic and elicits antibodies that neutralize all HAstV-2 strains. Taken together, our results have broad implications for rational selection of vaccine strains that do not contain prolines in antigenic loops, so as to elicit antibodies against diverse loop conformations.

    IMPORTANCEHuman astroviruses (HAstVs) infect nearly every person in the world during childhood and cause diarrhea, vomiting, and fever. In this study, we investigated how several strains of HAstV are resistant to a virus-neutralizing monoclonal antibody. We determined the crystal structure of the capsid protein spike domain from one of these HAstV strains and found that

  3. Generation and characterization of ixekizumab, a humanized monoclonal antibody that neutralizes interleukin-17A

    Directory of Open Access Journals (Sweden)

    Liu L

    2016-04-01

    Full Text Available Ling Liu,1 Jirong Lu,1 Barrett W Allan,2 Ying Tang,2 Jonathan Tetreault,1 Chi-kin Chow,1 Barbra Barmettler,2 James Nelson,2 Holly Bina,1 Lihua Huang,3 Victor J Wroblewski,4 Kristine Kikly1 1Biotechnology Discovery Research, Indianapolis, IN, 2Applied Molecular Evolution, Lilly Biotechnology Center, San Diego, CA, 3Bioproduct Research and Development, 4Drug Disposition, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, USA Abstract: Interleukin (IL-17A exists as a homodimer (A/A or as a heterodimer (A/F with IL-17F. IL-17A is expressed by a subset of T-cells, called Th17 cells, at inflammatory sites. Most cell types can respond to the local production of IL-17A because of the near ubiquitous expression of IL-17A receptors, IL-17RA and IL-17RC. IL-17A stimulates the release of cytokines and chemokines designed to recruit and activate both neutrophils and memory T-cells to the site of injury or inflammation and maintain a proinflammatory state. IL-17A-producing pathogenic T-cells contribute to the pathogenesis of autoimmune diseases, including psoriasis, psoriatic arthritis, rheumatoid arthritis, and ankylosing spondylitis. This study describes the generation and characterization of ixekizumab, a humanized IgG4 variant IL-17A-neutralizing antibody. Ixekizumab binds human and cynomolgus monkey IL-17A with high affinity and binds rabbit IL-17A weakly but does not bind to rodent IL-17A or other IL-17 family members. Ixekizumab effectively inhibits the interaction between IL-17A and its receptor in binding assays and potently blocks IL-17A-induced GRO or KC secretion in cell-based assays. In an in vivo mouse pharmcodynamic model, ixekizumab blocks human IL-17A-induced mouse KC secretion. These data provide a comprehensive preclinical characterization of ixekizumab, for which the efficacy and safety have been demonstrated in human clinical trials in psoriasis and psoriatic arthritis.Keywords: ixekizumab, IL-17A monoclonal antibody

  4. Ebola virus-like particles produced in insect cells exhibit dendritic cell stimulating activity and induce neutralizing antibodies

    International Nuclear Information System (INIS)

    Ye Ling; Lin Jianguo; Sun Yuliang; Bennouna, Soumaya; Lo, Michael; Wu Qingyang; Bu Zhigao; Pulendran, Bali; Compans, Richard W.; Yang Chinglai

    2006-01-01

    Recombinant baculoviruses (rBV) expressing Ebola virus VP40 (rBV-VP40) or GP (rBV-GP) proteins were generated. Infection of Sf9 insect cells by rBV-VP40 led to assembly and budding of filamentous particles from the cell surface as shown by electron microscopy. Ebola virus-like particles (VLPs) were produced by coinfection of Sf9 cells with rBV-VP40 and rBV-GP, and incorporation of Ebola GP into VLPs was demonstrated by SDS-PAGE and Western blot analysis. Recombinant baculovirus infection of insect cells yielded high levels of VLPs, which were shown to stimulate cytokine secretion from human dendritic cells similar to VLPs produced in mammalian cells. The immunogenicity of Ebola VLPs produced in insect cells was evaluated by immunization of mice. Analysis of antibody responses showed that most of the GP-specific antibodies were of the IgG2a subtype, while no significant level of IgG1 subtype antibodies specific for GP was induced, indicating the induction of a Th1-biased immune response. Furthermore, sera from Ebola VLP immunized mice were able to block infection by Ebola GP pseudotyped HIV virus in a single round infection assay, indicating that a neutralizing antibody against the Ebola GP protein was induced. These results show that production of Ebola VLPs in insect cells using recombinant baculoviruses represents a promising approach for vaccine development against Ebola virus infection

  5. Escape from neutralization by the respiratory syncytial virus-specific neutralizing monoclonal antibody palivizumab is driven by changes in on-rate of binding to the fusion protein

    Energy Technology Data Exchange (ETDEWEB)

    Bates, John T. [The Vanderbilt Vaccine Center, Departments of Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN (United States); Keefer, Christopher J. [The Vanderbilt Vaccine Center, Departments of Pediatrics, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN (United States); Slaughter, James C. [The Vanderbilt Vaccine Center, Departments of Biostatistics and Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN (United States); Kulp, Daniel W. [IAVI Neutralizing Antibody Center and Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA (United States); Schief, William R. [IAVI Neutralizing Antibody Center and Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA (United States); Center for HIV/AIDS Vaccine Immunology and Immunogen Discovery, The Scripps Research Institute, La Jolla, CA (United States); Crowe, James E., E-mail: james.crowe@vanderbilt.edu [The Vanderbilt Vaccine Center, Departments of Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN (United States); The Vanderbilt Vaccine Center, Departments of Pediatrics, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN (United States)

    2014-04-15

    The role of binding kinetics in determining neutralizing potency for antiviral antibodies is poorly understood. While it is believed that increased steady-state affinity correlates positively with increased virus-neutralizing activity, the relationship between association or dissociation rate and neutralization potency is unclear. We investigated the effect of naturally-occurring antibody resistance mutations in the RSV F protein on the kinetics of binding to palivizumab. Escape from palivizumab-mediated neutralization of RSV occurred with reduced association rate (K{sub on}) for binding to RSV F protein, while alteration of dissociation rate (K{sub off}) did not significantly affect neutralizing activity. Interestingly, linkage of reduced K{sub on} with reduced potency mirrored the effect of increased K{sub on} found in a high-affinity enhanced potency palivizumab variant (motavizumab). These data suggest that association rate is the dominant factor driving neutralization potency for antibodies to RSV F protein antigenic site A and determines the potency of antibody somatic variants or efficiency of escape of viral glycoprotein variants. - Highlights: • The relationship of affinity to neutralization for virus antibodies is uncertain. • Palivizumab binds to RSV escape mutant fusion proteins, but with reduced affinity. • Association rate (K{sub on}) correlated well with the potency of neutralization.

  6. Escape from neutralization by the respiratory syncytial virus-specific neutralizing monoclonal antibody palivizumab is driven by changes in on-rate of binding to the fusion protein

    International Nuclear Information System (INIS)

    Bates, John T.; Keefer, Christopher J.; Slaughter, James C.; Kulp, Daniel W.; Schief, William R.; Crowe, James E.

    2014-01-01

    The role of binding kinetics in determining neutralizing potency for antiviral antibodies is poorly understood. While it is believed that increased steady-state affinity correlates positively with increased virus-neutralizing activity, the relationship between association or dissociation rate and neutralization potency is unclear. We investigated the effect of naturally-occurring antibody resistance mutations in the RSV F protein on the kinetics of binding to palivizumab. Escape from palivizumab-mediated neutralization of RSV occurred with reduced association rate (K on ) for binding to RSV F protein, while alteration of dissociation rate (K off ) did not significantly affect neutralizing activity. Interestingly, linkage of reduced K on with reduced potency mirrored the effect of increased K on found in a high-affinity enhanced potency palivizumab variant (motavizumab). These data suggest that association rate is the dominant factor driving neutralization potency for antibodies to RSV F protein antigenic site A and determines the potency of antibody somatic variants or efficiency of escape of viral glycoprotein variants. - Highlights: • The relationship of affinity to neutralization for virus antibodies is uncertain. • Palivizumab binds to RSV escape mutant fusion proteins, but with reduced affinity. • Association rate (K on ) correlated well with the potency of neutralization

  7. Human Neutralizing Monoclonal Antibody Inhibition of Middle East Respiratory Syndrome Coronavirus Replication in the Common Marmoset.

    Science.gov (United States)

    Chen, Zhe; Bao, Linlin; Chen, Cong; Zou, Tingting; Xue, Ying; Li, Fengdi; Lv, Qi; Gu, Songzhi; Gao, Xiaopan; Cui, Sheng; Wang, Jianmin; Qin, Chuan; Jin, Qi

    2017-06-15

    Middle East respiratory syndrome coronavirus (MERS-CoV) infection in humans is highly lethal, with a fatality rate of 35%. New prophylactic and therapeutic strategies to combat human infections are urgently needed. We isolated a fully human neutralizing antibody, MCA1, from a human survivor. The antibody recognizes the receptor-binding domain of MERS-CoV S glycoprotein and interferes with the interaction between viral S and the human cellular receptor human dipeptidyl peptidase 4 (DPP4). To our knowledge, this study is the first to report a human neutralizing monoclonal antibody that completely inhibits MERS-CoV replication in common marmosets. Monotherapy with MCA1 represents a potential alternative treatment for human infections with MERS-CoV worthy of evaluation in clinical settings. © Crown copyright 2017.

  8. Neutralizing monoclonal antibodies against hepatitis C virus E2 protein bind discontinuous epitopes and inhibit infection at a postattachment step

    DEFF Research Database (Denmark)

    Sabo, Michelle C; Luca, Vincent C; Prentoe, Jannick

    2011-01-01

    The E2 glycoprotein of hepatitis C virus (HCV) mediates viral attachment and entry into target hepatocytes and elicits neutralizing antibodies in infected patients. To characterize the structural and functional basis of HCV neutralization, we generated a novel panel of 78 monoclonal antibodies (M...

  9. Determination of low tetanus or diphtheria antitoxin titers in sera by a toxin neutralization assay and a modified toxin-binding inhibition test

    Directory of Open Access Journals (Sweden)

    M.H. Sonobe

    2007-01-01

    Full Text Available A method for the screening of tetanus and diphtheria antibodies in serum using anatoxin (inactivated toxin instead of toxin was developed as an alternative to the in vivo toxin neutralization assay based on the toxin-binding inhibition test (TOBI test. In this study, the serum titers (values between 1.0 and 19.5 IU measured by a modified TOBI test (Modi-TOBI test and toxin neutralization assays were correlated (P < 0.0001. Titers of tetanus or diphtheria antibodies were evaluated in serum samples from guinea pigs immunized with tetanus toxoid, diphtheria-tetanus or triple vaccine. For the Modi-TOBI test, after blocking the microtiter plates, standard tetanus or diphtheria antitoxin and different concentrations of guinea pig sera were incubated with the respective anatoxin. Twelve hours later, these samples were transferred to a plate previously coated with tetanus or diphtheria antitoxin to bind the remaining anatoxin. The anatoxin was then detected using a peroxidase-labeled tetanus or diphtheria antitoxin. Serum titers were calculated using a linear regression plot of the results for the corresponding standard antitoxin. For the toxin neutralization assay, L+/10/50 doses of either toxin combined with different concentrations of serum samples were inoculated into mice for anti-tetanus detection, or in guinea pigs for anti-diphtheria detection. Both assays were suitable for determining wide ranges of antitoxin levels. The linear regression plots showed high correlation coefficients for tetanus (r² = 0.95, P < 0.0001 and for diphtheria (r² = 0.93, P < 0.0001 between the in vitro and the in vivo assays. The standardized method is appropriate for evaluating titers of neutralizing antibodies, thus permitting the in vitro control of serum antitoxin levels.

  10. 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.

  11. Specific-pathogen-free chickens vaccinated with a live FAdV-4 vaccine are fully protected against a severe challenge even in the absence of neutralizing antibodies.

    Science.gov (United States)

    Schonewille, Esther; Jaspers, Ron; Paul, Guntram; Hess, Michael

    2010-06-01

    By adapting a very virulent fowl adenovirus serotype 4 (FAdV-4) to a fibroblast cell line (QT35) instead of growing the virus in chicken embryo liver cells or chicken kidney cells, it was possible to attenuate the virus. Birds infected with the attenuated virus (FAdV-4/QT35) on the first day of life expressed no adverse clinical signs and no mortality. Intramuscular challenge with the virulent virus grown on chicken embryo liver cells (FAdV-4/CEL) at 21 days of life induced high mortality in previously nonvaccinated birds, whereas none of the birds vaccinated at 1 day old with FAdV-4/QT35 died due to this challenge. Applying enzyme-linked immunosorbent assay and virus neutralization assay, only a weak antibody response could be detected in some birds following vaccination, a response that increased directly after challenge. Nonvaccinated birds displayed a delayed development of antibodies after challenge as compared to previously vaccinated birds. Even birds that did not develop a measurable neutralizing antibody titer prior to challenge were protected from the adverse effects of the virulent FAdV-4/CEL, a phenomenon not described so far for FAdVs. Altogether, the present investigation underlines that neutralizing antibodies are not needed to protect chickens against a severe infection with a virulent fowl adenovirus.

  12. Monoclonal antibodies against human angiotensinogen, their characterization and use in an angiotensinogen enzyme linked immunosorbent assay.

    Science.gov (United States)

    Rubin, I; Lykkegaard, S; Olsen, A A; Selmer, J; Ballegaard, M

    1988-01-01

    Monoclonal antibodies were produced against human angiotensinogen. An enzyme linked immunosorbent assay (ELISA) was developed using a high affinity monoclonal antibody as catching antibody and a polyclonal rabbit anti human angiotensinogen antibody as detecting antibody in a "sandwich" ELISA. Linear range of the ELISA was 15-450 pmol/l of human angiotensinogen. Intra- and inter- assay variation coefficients were in the range of 2% to 8%. A correlation coefficient, r = 0.97, (n = 20), with values obtained by radioimmunoassay. This correlation coefficient, obtained by using both normal and pregnant sera, confirmed that the ELISA fulfill the requirements for clinical useful assay. Characterization of the antibodies were performed with respect to affinity constant and epitopes.

  13. Cellular impedance measurement as a new tool for poxvirus titration, antibody neutralization testing and evaluation of antiviral substances

    International Nuclear Information System (INIS)

    Witkowski, Peter T.; Schuenadel, Livia; Wiethaus, Julia; Bourquain, Daniel R.; Kurth, Andreas; Nitsche, Andreas

    2010-01-01

    Research highlights: → Real-time data acquisition by RT-CES requires low operative effort. → Time to result is reduced by using RT-CES instead of conventional methods. → RT-CES enables quantification of virus titers in unknown samples. → RT-CES is a useful tool for high-throughput characterization of antiviral agents. → An RT-CES-based virus neutralization test was established. -- Abstract: Impedance-based biosensing known as real-time cell electronic sensing (RT-CES) belongs to an emerging technology for analyzing the status of cells in vitro. In the present study protocols were developed for an RT-CES-based system (xCELLigence TM , Roche Applied Science, ACEA Biosciences Inc.) to supplement conventional techniques in pox virology. First, proliferation of cells susceptible to orthopoxviruses was monitored. For virus titration cells were infected with vaccinia virus and cell status, represented by the dimensionless impedance-based cell index (CI), was monitored. A virus-dose dependent decrease in electrical impedance could be shown. Calculation of calibration curves at a suitable CI covering a dynamic range of 4 log enabled the quantification of virus titers in unknown samples. Similarly, antiviral effects could be determined as shown for anti-poxviral agents ST-246 and Cidofovir. Published values for the in vitro concentration that inhibited virus replication by 50% (IC 50 ) could be confirmed while cytotoxicity in effective concentrations was excluded in long-term incubation experiments. Finally, an RT-CES-based virus neutralization test was established. Various poxvirus-specific antibodies were examined for their neutralizing activity and a calculation mode for the neutralizing antibody titer was introduced. In summary, the presented RT-CES-based methods outmatch end-point assays by observing the cell population throughout the entire experiment while workload and time to result are reduced.

  14. Supersensitive gastrin assay using antibodies raised against a cholecystokinin homolog

    DEFF Research Database (Denmark)

    Rehfeld, Jens F; Ericsson, Peter

    2012-01-01

    Peptide hormones may occur in particularly low amounts in samples from small animals. Hence, in a rat microdialysis study conventional immunoassays were not sufficiently sensitive to measure gastrin in the dialysis samples. We therefore exploited the observation that antibodies raised against...... that obtained with the most avid conventional gastrin antibodies. The results may encourage similar approaches for other peptides using homologue-raised antibodies when supersensitivity is required....

  15. Genetic signatures in the envelope glycoproteins of HIV-1 that associate with broadly neutralizing antibodies.

    Directory of Open Access Journals (Sweden)

    S Gnanakaran

    Full Text Available A steady increase in knowledge of the molecular and antigenic structure of the gp120 and gp41 HIV-1 envelope glycoproteins (Env is yielding important new insights for vaccine design, but it has been difficult to translate this information to an immunogen that elicits broadly neutralizing antibodies. To help bridge this gap, we used phylogenetically corrected statistical methods to identify amino acid signature patterns in Envs derived from people who have made potently neutralizing antibodies, with the hypothesis that these Envs may share common features that would be useful for incorporation in a vaccine immunogen. Before attempting this, essentially as a control, we explored the utility of our computational methods for defining signatures of complex neutralization phenotypes by analyzing Env sequences from 251 clonal viruses that were differentially sensitive to neutralization by the well-characterized gp120-specific monoclonal antibody, b12. We identified ten b12-neutralization signatures, including seven either in the b12-binding surface of gp120 or in the V2 region of gp120 that have been previously shown to impact b12 sensitivity. A simple algorithm based on the b12 signature pattern was predictive of b12 sensitivity/resistance in an additional blinded panel of 57 viruses. Upon obtaining these reassuring outcomes, we went on to apply these same computational methods to define signature patterns in Env from HIV-1 infected individuals who had potent, broadly neutralizing responses. We analyzed a checkerboard-style neutralization dataset with sera from 69 HIV-1-infected individuals tested against a panel of 25 different Envs. Distinct clusters of sera with high and low neutralization potencies were identified. Six signature positions in Env sequences obtained from the 69 samples were found to be strongly associated with either the high or low potency responses. Five sites were in the CD4-induced coreceptor binding site of gp120, suggesting an

  16. Structures of phlebovirus glycoprotein Gn and identification of a neutralizing antibody epitope.

    Science.gov (United States)

    Wu, Yan; Zhu, Yaohua; Gao, Feng; Jiao, Yongjun; Oladejo, Babayemi O; Chai, Yan; Bi, Yuhai; Lu, Shan; Dong, Mengqiu; Zhang, Chang; Huang, Guangmei; Wong, Gary; Li, Na; Zhang, Yanfang; Li, Yan; Feng, Wen-Hai; Shi, Yi; Liang, Mifang; Zhang, Rongguang; Qi, Jianxun; Gao, George F

    2017-09-05

    Severe fever with thrombocytopenia syndrome virus (SFTSV) and Rift Valley fever virus (RVFV) are two arthropod-borne phleboviruses in the Bunyaviridae family, which cause severe illness in humans and animals. Glycoprotein N (Gn) is one of the envelope proteins on the virus surface and is a major antigenic component. Despite its importance for virus entry and fusion, the molecular features of the phleboviruse Gn were unknown. Here, we present the crystal structures of the Gn head domain from both SFTSV and RVFV, which display a similar compact triangular shape overall, while the three subdomains (domains I, II, and III) making up the Gn head display different arrangements. Ten cysteines in the Gn stem region are conserved among phleboviruses, four of which are responsible for Gn dimerization, as revealed in this study, and they are highly conserved for all members in Bunyaviridae Therefore, we propose an anchoring mode on the viral surface. The complex structure of the SFTSV Gn head and human neutralizing antibody MAb 4-5 reveals that helices α6 in subdomain III is the key component for neutralization. Importantly, the structure indicates that domain III is an ideal region recognized by specific neutralizing antibodies, while domain II is probably recognized by broadly neutralizing antibodies. Collectively, Gn is a desirable vaccine target, and our data provide a molecular basis for the rational design of vaccines against the diseases caused by phleboviruses and a model for bunyavirus Gn embedding on the viral surface.

  17. Neutralizing antibodies against flaviviruses, Babanki virus, and Rift Valley fever virus in Ugandan bats.

    Science.gov (United States)

    Kading, Rebekah C; Kityo, Robert M; Mossel, Eric C; Borland, Erin M; Nakayiki, Teddie; Nalikka, Betty; Nyakarahuka, Luke; Ledermann, Jeremy P; Panella, Nicholas A; Gilbert, Amy T; Crabtree, Mary B; Peterhans, Julian Kerbis; Towner, Jonathan S; Amman, Brian R; Sealy, Tara K; Nichol, Stuart T; Powers, Ann M; Lutwama, Julius J; Miller, Barry R

    2018-01-01

    Introduction: A number of arboviruses have previously been isolated from naturally-infected East African bats, however the role of bats in arbovirus maintenance is poorly understood. The aim of this study was to investigate the exposure history of Ugandan bats to a panel of arboviruses. Materials and methods: Insectivorous and fruit bats were captured from multiple locations throughout Uganda during 2009 and 2011-2013. All serum samples were tested for neutralizing antibodies against West Nile virus (WNV), yellow fever virus (YFV), dengue 2 virus (DENV-2), Zika virus (ZIKV), Babanki virus (BBKV), and Rift Valley fever virus (RVFV) by plaque reduction neutralization test (PRNT). Sera from up to 626 bats were screened for antibodies against each virus. Results and Discussion:  Key findings include the presence of neutralizing antibodies against RVFV in 5/52 (9.6%) of little epauletted fruit bats ( Epomophorus labiatus ) captured from Kawuku and 3/54 (5.6%) Egyptian rousette bats from Kasokero cave. Antibodies reactive to flaviviruses were widespread across bat taxa and sampling locations. Conclusion: The data presented demonstrate the widespread exposure of bats in Uganda to arboviruses, and highlight particular virus-bat associations that warrant further investigation.

  18. Broad antibody mediated cross-neutralization and preclinical immunogenicity of new codon-optimized HIV-1 clade CRF02_AG and G primary isolates.

    Directory of Open Access Journals (Sweden)

    Simon M Agwale

    Full Text Available Creation of an effective vaccine for HIV has been an elusive goal of the scientific community for almost 30 years. Neutralizing antibodies are assumed to be pivotal to the success of a prophylactic vaccine but previous attempts to make an immunogen capable of generating neutralizing antibodies to primary "street strain" isolates have resulted in responses of very limited breadth and potency. The objective of the study was to determine the breadth and strength of neutralizing antibodies against autologous and heterologous primary isolates in a cohort of HIV-1 infected Nigerians and to characterize envelopes from subjects with particularly broad or strong immune responses for possible use as vaccine candidates in regions predominated by HIV-1 CRF02_AG and G subtypes. Envelope vectors from a panel of primary Nigerian isolates were constructed and tested with plasma/sera from the same cohort using the PhenoSense HIV neutralizing antibody assay (Monogram Biosciences Inc, USA to assess the breadth and potency of neutralizing antibodies. The immediate goal of this study was realized by the recognition of three broadly cross-neutralizing sera: (NG2-clade CRF02_AG, NG3-clade CRF02_AG and NG9- clade G. Based on these findings, envelope gp140 sequences from NG2 and NG9, complemented with a gag sequence (Clade G and consensus tat (CRF02_AG and G antigens have been codon-optimized, synthesized, cloned and evaluated in BALB/c mice. The intramuscular administration of these plasmid DNA constructs, followed by two booster DNA immunizations, induced substantial specific humoral response against all constructs and strong cellular responses against the gag and tat constructs. These preclinical findings provide a framework for the design of candidate vaccine for use in regions where the HIV-1 epidemic is driven by clades CRF02_AG and G.

  19. Broad antibody mediated cross-neutralization and preclinical immunogenicity of new codon-optimized HIV-1 clade CRF02_AG and G primary isolates.

    Science.gov (United States)

    Agwale, Simon M; Forbi, Joseph C; Notka, Frank; Wrin, Terri; Wild, Jens; Wagner, Ralf; Wolf, Hans

    2011-01-01

    Creation of an effective vaccine for HIV has been an elusive goal of the scientific community for almost 30 years. Neutralizing antibodies are assumed to be pivotal to the success of a prophylactic vaccine but previous attempts to make an immunogen capable of generating neutralizing antibodies to primary "street strain" isolates have resulted in responses of very limited breadth and potency. The objective of the study was to determine the breadth and strength of neutralizing antibodies against autologous and heterologous primary isolates in a cohort of HIV-1 infected Nigerians and to characterize envelopes from subjects with particularly broad or strong immune responses for possible use as vaccine candidates in regions predominated by HIV-1 CRF02_AG and G subtypes. Envelope vectors from a panel of primary Nigerian isolates were constructed and tested with plasma/sera from the same cohort using the PhenoSense HIV neutralizing antibody assay (Monogram Biosciences Inc, USA) to assess the breadth and potency of neutralizing antibodies. The immediate goal of this study was realized by the recognition of three broadly cross-neutralizing sera: (NG2-clade CRF02_AG, NG3-clade CRF02_AG and NG9- clade G). Based on these findings, envelope gp140 sequences from NG2 and NG9, complemented with a gag sequence (Clade G) and consensus tat (CRF02_AG and G) antigens have been codon-optimized, synthesized, cloned and evaluated in BALB/c mice. The intramuscular administration of these plasmid DNA constructs, followed by two booster DNA immunizations, induced substantial specific humoral response against all constructs and strong cellular responses against the gag and tat constructs. These preclinical findings provide a framework for the design of candidate vaccine for use in regions where the HIV-1 epidemic is driven by clades CRF02_AG and G.

  20. Adjuvant-Mediated Epitope Specificity and Enhanced Neutralizing Activity of Antibodies Targeting Dengue Virus Envelope Protein

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    Denicar Lina Nascimento Fabris Maeda

    2017-09-01

    Full Text Available The heat-labile toxins (LT produced by enterotoxigenic Escherichia coli display adjuvant effects to coadministered antigens, leading to enhanced production of serum antibodies. Despite extensive knowledge of the adjuvant properties of LT derivatives, including in vitro-generated non-toxic mutant forms, little is known about the capacity of these adjuvants to modulate the epitope specificity of antibodies directed against antigens. This study characterizes the role of LT and its non-toxic B subunit (LTB in the modulation of antibody responses to a coadministered antigen, the dengue virus (DENV envelope glycoprotein domain III (EDIII, which binds to surface receptors and mediates virus entry into host cells. In contrast to non-adjuvanted or alum-adjuvanted formulations, antibodies induced in mice immunized with LT or LTB showed enhanced virus-neutralization effects that were not ascribed to a subclass shift or antigen affinity. Nonetheless, immunosignature analyses revealed that purified LT-adjuvanted EDIII-specific antibodies display distinct epitope-binding patterns with regard to antibodies raised in mice immunized with EDIII or the alum-adjuvanted vaccine. Notably, the analyses led to the identification of a specific EDIII epitope located in the EF to FG loop, which is involved in the entry of DENV into eukaryotic cells. The present results demonstrate that LT and LTB modulate the epitope specificity of antibodies generated after immunization with coadministered antigens that, in the case of EDIII, was associated with the induction of neutralizing antibody responses. These results open perspectives for the more rational development of vaccines with enhanced protective effects against DENV infections.

  1. Crystal structure and size-dependent neutralization properties of HK20, a human monoclonal antibody binding to the highly conserved heptad repeat 1 of gp41.

    Science.gov (United States)

    Sabin, Charles; Corti, Davide; Buzon, Victor; Seaman, Mike S; Lutje Hulsik, David; Hinz, Andreas; Vanzetta, Fabrizia; Agatic, Gloria; Silacci, Chiara; Mainetti, Lara; Scarlatti, Gabriella; Sallusto, Federica; Weiss, Robin; Lanzavecchia, Antonio; Weissenhorn, Winfried

    2010-11-18

    The human monoclonal antibody (mAb) HK20 neutralizes a broad spectrum of primary HIV-1 isolates by targeting the highly conserved heptad repeat 1 (HR1) of gp41, which is transiently exposed during HIV-1 entry. Here we present the crystal structure of the HK20 Fab in complex with a gp41 mimetic 5-Helix at 2.3 Å resolution. HK20 employs its heavy chain CDR H2 and H3 loops to bind into a conserved hydrophobic HR1 pocket that is occupied by HR2 residues in the gp41 post fusion conformation. Compared to the previously described HR1-specific mAb D5, HK20 approaches its epitope with a different angle which might favor epitope access and thus contribute to its higher neutralization breadth and potency. Comparison of the neutralization activities of HK20 IgG, Fab and scFv employing both single cycle and multiple cycle neutralization assays revealed much higher potencies for the smaller Fab and scFv over IgG, implying that the target site is difficult to access for complete antibodies. Nevertheless, two thirds of sera from HIV-1 infected individuals contain significant titers of HK20-inhibiting antibodies. The breadth of neutralization of primary isolates across all clades, the higher potencies for C-clade viruses and the targeting of a distinct site as compared to the fusion inhibitor T-20 demonstrate the potential of HK20 scFv as a therapeutic tool.

  2. Genotoxicity testing: Comparison of the γH2AX focus assay with the alkaline and neutral comet assays.

    Science.gov (United States)

    Nikolova, Teodora; Marini, Federico; Kaina, Bernd

    2017-10-01

    Genotoxicity testing relies on the quantitative measurement of adverse effects, such as chromosome aberrations, micronuclei, and mutations, resulting from primary DNA damage. Ideally, assays will detect DNA damage and cellular responses with high sensitivity, reliability, and throughput. Several novel genotoxicity assays may fulfill these requirements, including the comet assay and the more recently developed γH2AX assay. Although they are thought to be specific for genotoxicants, a systematic comparison of the assays has not yet been undertaken. In the present study, we compare the γH2AX focus assay with the alkaline and neutral versions of the comet assay, as to their sensitivities and limitations for detection of genetic damage. We investigated the dose-response relationships of γH2AX foci and comet tail intensities at various times following treatment with four prototypical genotoxicants, methyl methanesulfonate (MMS), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), mitomycin C, and hydrogen peroxide (H 2 O 2 ) and we tested whether there is a correlation between the endpoints, i.e., alkali-labile sites and DNA strand breaks on the one hand and the cell's response to DNA double-strand breaks and blocked replication forks on the other. Induction of γH2AX foci gave a linear dose response and all agents tested were positive in the assay. The increase in comet tail intensity was also a function of dose; however, mitomycin C was almost completely ineffective in the comet assay, and the doses needed to achieve a significant effect were somewhat higher for some treatments in the comet assay than in the γH2AX foci assay, which was confirmed by threshold analysis. There was high correlation between tail intensity and γH2AX foci for MMS and H 2 O 2 , less for MNNG, and none for mitomycin C. From this we infer that the γH2AX foci assay is more reliable, sensitive, and robust than the comet assay for detecting genotoxicant-induced DNA damage. Copyright © 2017 Elsevier

  3. Development and evaluation of an anti-rabies virus phosphoprotein-specific monoclonal antibody for detection of rabies neutralizing antibodies using RFFIT.

    Science.gov (United States)

    Um, Jihye; Chun, Byung Chul; Lee, Yeong Seon; Hwang, Kyu Jam; Yang, Dong-Kun; Park, Jun-Sun; Kim, Su Yeon

    2017-12-01

    Rabies is a major public health problem with a fatality rate close to 100%; however, complete prevention can be achieved through pre- or post-exposure prophylaxis. The rapid fluorescent focus inhibition test (RFFIT) is one of the recommended testing methods to determine the production of neutralizing antibodies after vaccination. Here, we report the development of a new monoclonal antibody (mAb) designed to react specifically with Rabies virus (RABV) phosphoprotein (P protein), and the evaluation of its applicability to the RFFIT and its effectiveness as a diagnostic reagent for human rabies. The mAb KGH P 16B8 was produced to target the P protein of the Korean KGH RABV strain. An indirect immunofluorescence assay (IFA) was conducted to detect various strains of RABV in various cell lines. Alexa-conjugated KGH P 16B8 (16B8-Alexa) was developed for the RFFIT. The IFA test could detect RABV up to a 1:2,500 dilution, with a detection limit comparable to that of a commercial diagnostic reagent. The sensitivity, specificity, positive predictive value, and negative predictive value of the RFFIT using 16B8-Alexa in 414 clinical specimens were 98.67%, 99.47%, 99.55%, and 98.42%, respectively. The results of the RFFIT with 16B8-Alexa were strongly correlated with those obtained using an existing commercial diagnostic reagent (r = 0.995, prabies neutralizing antibody titer and establish a diagnosis in human. Thus, 16B8-Alexa is expected to serve as an alternative diagnostic reagent that is widely accessible, with potentially broad applications beyond those of the RFFIT in Korea. Further studies with 16B8-Alexa should provide insight into the immunological mechanism of the P protein of Korean RABV.

  4. [A double antibody sandwich ELISA based assay for titration of severe fever with thrombocytopenia syndrome virus].

    Science.gov (United States)

    Liu, Lin; Zhang, Quan-Fu; Li, Chuan; Li, Jian-Dong; Jiang, Xiao-Lin; Zhang, Fu-Shun; Wu, Wei; Liang, Mi-Fang; Li, De-Xin

    2013-06-01

    To develop an assay for titration of severe fever with thrombocytopenia syndrome virus (SFTSV) based on double antibody sandwich ELISA. A double antibody sandwich ELISA was developed for detection of SFTSV based on SFTSV nucleocapsid (N) protein specific poly- and monoclonal antibodies, procedures were optimized and evaluated. This ELISA based titration assay was compared with fluorescence assasy and plaque assay based titration method. The results suggested that the titers obtained by ELISA based method are consistent with those obtained by IFA based method (R = 0.999) and the plaque assay titration method (R = 0.949). The novel ELISA based titration method with high sensitivity and specificity is easy to manage and perform, and can overcome the subjectivity associated with result determination of the fluorescence assay and plaque assay based methods. The novel ELISA based titration method can also be applied to high throughput detection.

  5. Antibody-dependent cellular cytotoxicity and neutralizing activity in sera of HIV-1-infected mothers and their children.

    Science.gov (United States)

    Broliden, K; Sievers, E; Tovo, P A; Moschese, V; Scarlatti, G; Broliden, P A; Fundaro, C; Rossi, P

    1993-01-01

    The prognostic and protective role of antibodies mediating cellular cytotoxicity (ADCC) and neutralization was evaluated in sera of HIV-1-infected mothers and their consecutively followed children. The presence and titres of ADCC mediating and/or neutralizing antibodies in maternal sera did not predict HIV-1 infection in their respective children. No significant difference in the sera from the children was seen when comparing the presence of neutralizing antibodies between the uninfected and infected children. Stratification of the infected group according to clinical status revealed differences. Only one of 24 AIDS patients had a high neutralizing titre against IIIB. Four patients had a very low titre and the remaining had no detectable neutralizing antibodies at all. In contrast, 10/17 infected non-AIDS children had neutralizing antibodies. Similarly, no significant difference was seen when comparing the presence of ADCC-mediating antibodies between the uninfected and the infected group of children. However, a significantly higher frequency of ADCC was seen in the seropositive non-AIDS children compared with the AIDS children. This study clearly shows that the presence of antibodies mediating ADCC and neutralization in infected children, 0-2 years old, is associated with a better clinical status and delayed disease progression. PMID:8324904

  6. Role of the Antigen Capture Pathway in the Induction of a Neutralizing Antibody Response to Anthrax Protective Antigen

    Directory of Open Access Journals (Sweden)

    Anita Verma

    2018-02-01

    Full Text Available Toxin neutralizing antibodies represent the major mode of protective immunity against a number of toxin-mediated bacterial diseases, including anthrax; however, the cellular mechanisms that lead to optimal neutralizing antibody responses remain ill defined. Here we show that the cellular binding pathway of anthrax protective antigen (PA, the binding component of anthrax toxin, determines the toxin neutralizing antibody response to this antigen. PA, which binds cellular receptors and efficiently enters antigen-presenting cells by receptor-mediated endocytosis, was found to elicit robust anti-PA IgG and toxin neutralizing antibody responses. In contrast, a receptor binding-deficient mutant of PA, which does not bind receptors and only inefficiently enters antigen-presenting cells by macropinocytosis, elicited very poor antibody responses. A chimeric protein consisting of the receptor binding-deficient PA mutant tethered to the binding subunit of cholera toxin, which efficiently enters cells using the cholera toxin receptor rather than the PA receptor, elicited an anti-PA IgG antibody response similar to that elicited by wild-type PA; however, the chimeric protein elicited a poor toxin neutralizing antibody response. Taken together, our results demonstrate that the antigen capture pathway can dictate the magnitudes of the total IgG and toxin neutralizing antibody responses to PA as well as the ratio of the two responses.

  7. The Effect of Induced Antibodies with Respect to Neutralization, Clearance Rate and Functional Activity in a Rabbit/Infliximab Model

    DEFF Research Database (Denmark)

    Henriksen, Maiken Lumby; Teisner, Ane; Kjeldsen, Jens

    2016-01-01

    Background: Therapeutic antibodies are a developing field for treatment of an expanding number of inflammatory diseases, including Crohn's disease. Treatment with monoclonal antibodies is frequently hampered by development of anti-drug antibodies (ADAs) that may compromise the treatment. Materials...... in patients. The applied assay technology is easily adapted to human plasma samples and/or other therapeutic antibodies, including fully humanized antibodies, for which immunogenicity also is observed....

  8. Neutralizing antibodies hamper IFNbeta bioactivity and treatment effect on MRI in patients with MS

    DEFF Research Database (Denmark)

    Sorensen, P Soelberg; Petersen, Thomas Tscherning; Kahr Mathiesen, Henrik

    2006-01-01

    We measured neutralizing antibodies (NABs) and the in vivo biologic response to interferon-beta on neopterin and beta(2)-microglobulin blood levels. All NAB-negative patients had an in vivo biologic response (full or partial), whereas all high-level positive patients had no response. High-level NAB...... patients had more MRI activity than NAB-negative patients (p = 0.031). Patients with a full response had less MRI activity than patients without biologic response (p = 0.032)....

  9. Vaccine-induced cross-genotype reactive neutralizing antibodies against hepatitis C virus

    DEFF Research Database (Denmark)

    Meunier, Jean-Christophe; Gottwein, Judith M; Houghton, Michael

    2011-01-01

    We detected cross-reactive neutralizing antibodies (NtAb) against hepatitis C virus (HCV) in chimpanzees vaccinated with HCV-1 (genotype 1a) recombinant E1/E2 envelope glycoproteins. Five vaccinated chimpanzees, protected following HCV-1 challenge, were initially studied using the heterologous H77......a, with limited reactivity against 2a and 3a. Our study provides encouragement for the development of a recombinant envelope-based vaccine against hepatitis C....

  10. Structure-based, targeted deglycosylation of HIV-1 gp120 and effects on neutralization sensitivity and antibody recognition

    International Nuclear Information System (INIS)

    Koch, Markus; Pancera, Marie; Kwong, Peter D.; Kolchinsky, Peter; Grundner, Christoph; Wang Liping; Hendrickson, Wayne A.; Sodroski, Joseph; Wyatt, Richard

    2003-01-01

    The human immunodeficiency virus (HIV-1) exterior envelope glycoprotein, gp120, mediates receptor binding and is the major target for neutralizing antibodies. Primary HIV-1 isolates are characteristically more resistant to broadly neutralizing antibodies, although the structural basis for this resistance remains obscure. Most broadly neutralizing antibodies are directed against functionally conserved gp120 regions involved in binding to either the primary virus receptor, CD4, or the viral coreceptor molecules that normally function as chemokine receptors. These antibodies are known as CD4 binding site (CD4BS) and CD4-induced (CD4i) antibodies, respectively. Inspection of the gp120 crystal structure reveals that although the receptor-binding regions lack glycosylation, sugar moieties lie proximal to both receptor-binding sites on gp120 and thus in proximity to both the CD4BS and the CD4i epitopes. In this study, guided by the X-ray crystal structure of gp120, we deleted four N-linked glycosylation sites that flank the receptor-binding regions. We examined the effects of selected changes on the sensitivity of two prototypic HIV-1 primary isolates to neutralization by antibodies. Surprisingly, removal of a single N-linked glycosylation site at the base of the gp120 third variable region (V3 loop) increased the sensitivity of the primary viruses to neutralization by CD4BS antibodies. Envelope glycoprotein oligomers on the cell surface derived from the V3 glycan-deficient virus were better recognized by a CD4BS antibody and a V3 loop antibody than were the wild-type glycoproteins. Absence of all four glycosylation sites rendered a primary isolate sensitive to CD4i antibody-mediated neutralization. Thus, carbohydrates that flank receptor-binding regions on gp120 protect primary HIV-1 isolates from antibody-mediated neutralization

  11. An efficiently cleaved HIV-1 clade C Env selectively binds to neutralizing antibodies.

    Directory of Open Access Journals (Sweden)

    Saikat Boliar

    Full Text Available An ideal HIV-1 Env immunogen is expected to mimic the native trimeric conformation for inducing broadly neutralizing antibody responses. The native conformation is dependent on efficient cleavage of HIV-1 Env. The clade B isolate, JRFL Env is efficiently cleaved when expressed on the cell surface. Here, for the first time, we report the identification of a native clade C Env, 4-2.J41 that is naturally and efficiently cleaved on the cell surface as confirmed by its biochemical and antigenic characteristics. In addition to binding to several conformation-dependent neutralizing antibodies, 4-2.J41 Env binds efficiently to the cleavage-dependent antibody PGT151; thus validating its native cleaved conformation. In contrast, 4-2.J41 Env occludes non-neutralizing epitopes. The cytoplasmic-tail of 4-2.J41 Env plays an important role in maintaining its conformation. Furthermore, codon optimization of 4-2.J41 Env sequence significantly increases its expression while retaining its native conformation. Since clade C of HIV-1 is the prevalent subtype, identification and characterization of this efficiently cleaved Env would provide a platform for rational immunogen design.

  12. Cross neutralizing antibodies in hamsters vaccinated with leptospiral bacterins produced with three serovars of serogroup Sejroe

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    Rosana Tabata

    2002-09-01

    Full Text Available Three leptospiral bacterins, produced with different serovars of Serogroup Sejroe, namely the hardjo (bacterin A, wolffi (bacterin B and guaricura (bacterin C, were evaluated in male hamsters (Mesocricetus auratus by comparing the agglutinating and neutralizing antibodies titers using microscopic agglutination (MAT and in vitro growth inhibition (GIT tests. The immunization schedule was based on two 1.0 mL doses of non-diluted formalininactivated whole culture bacterin given through subcutaneous route with 10-day interval. The challenge was performed ten days after the second vaccine dose, when the animals were inoculated with 0.2 mL of non-inactivated cultures of each serovar through intraperitoneal route. On the 21st post-challenge day (PCD, all animals were bled and their sera were joined in pools (n=8 and tested by MAT and GIT. All vaccinated and control animals presented no clinical signs of leptospirosis after the challenge, but the serovar guaricura was isolated from the kidneys of control animals on the 21st PCD. The MAT results showed cross agglutinins between serovars hardjo and wolffi, and between wolffi and guaricura. The GIT results revealed the presence of cross neutralizing antibodies between serovars wolffi or guaricura against hardjo, wolffi and guaricura. It was found that the tested strain of serovar hardjo did not produce detectable levels of neutralizing antibodies, indicating its poor immunogenicity.

  13. Quantification of Lyssavirus-Neutralizing Antibodies Using Vesicular Stomatitis Virus Pseudotype Particles

    Directory of Open Access Journals (Sweden)

    Sarah Moeschler

    2016-09-01

    Full Text Available Rabies is a highly fatal zoonotic disease which is primarily caused by rabies virus (RABV although other members of the genus Lyssavirus can cause rabies as well. As yet, 14 serologically and genetically diverse lyssaviruses have been identified, mostly in bats. To assess the quality of rabies vaccines and immunoglobulin preparations, virus neutralization tests with live RABV are performed in accordance with enhanced biosafety standards. In the present work, a novel neutralization test is presented which takes advantage of a modified vesicular stomatitis virus (VSV from which the glycoprotein G gene has been deleted and replaced by reporter genes. This single-cycle virus was trans-complemented with RABV envelope glycoprotein. Neutralization of this pseudotype virus with RABV reference serum or immune sera from vaccinated mice showed a strong correlation with the rapid fluorescent focus inhibition test (RFFIT. Importantly, pseudotype viruses containing the envelope glycoproteins of other lyssaviruses were neutralized by reference serum to a significantly lesser extent or were not neutralized at all. Taken together, a pseudotype virus system has been successfully developed which allows the safe, fast, and sensitive detection of neutralizing antibodies directed against different lyssaviruses.

  14. Quantification of Lyssavirus-Neutralizing Antibodies Using Vesicular Stomatitis Virus Pseudotype Particles.

    Science.gov (United States)

    Moeschler, Sarah; Locher, Samira; Conzelmann, Karl-Klaus; Krämer, Beate; Zimmer, Gert

    2016-09-16

    Rabies is a highly fatal zoonotic disease which is primarily caused by rabies virus (RABV) although other members of the genus Lyssavirus can cause rabies as well. As yet, 14 serologically and genetically diverse lyssaviruses have been identified, mostly in bats. To assess the quality of rabies vaccines and immunoglobulin preparations, virus neutralization tests with live RABV are performed in accordance with enhanced biosafety standards. In the present work, a novel neutralization test is presented which takes advantage of a modified vesicular stomatitis virus (VSV) from which the glycoprotein G gene has been deleted and replaced by reporter genes. This single-cycle virus was trans-complemented with RABV envelope glycoprotein. Neutralization of this pseudotype virus with RABV reference serum or immune sera from vaccinated mice showed a strong correlation with the rapid fluorescent focus inhibition test (RFFIT). Importantly, pseudotype viruses containing the envelope glycoproteins of other lyssaviruses were neutralized by reference serum to a significantly lesser extent or were not neutralized at all. Taken together, a pseudotype virus system has been successfully developed which allows the safe, fast, and sensitive detection of neutralizing antibodies directed against different lyssaviruses.

  15. Lack of protection following passive transfer of polyclonal highly functional low-dose non-neutralizing antibodies.

    Directory of Open Access Journals (Sweden)

    Anne-Sophie Dugast

    Full Text Available Recent immune correlates analysis from the RV144 vaccine trial has renewed interest in the role of non-neutralizing antibodies in mediating protection from infection. While neutralizing antibodies have proven difficult to induce through vaccination, extra-neutralizing antibodies, such as those that mediate antibody-dependent cellular cytotoxicity (ADCC, are associated with long-term control of infection. However, while several non-neutralizing monoclonal antibodies have been tested for their protective efficacy in vivo, no studies to date have tested the protective activity of naturally produced polyclonal antibodies from individuals harboring potent ADCC activity. Because ADCC-inducing antibodies are highly enriched in elite controllers (EC, we passively transferred highly functional non-neutralizing polyclonal antibodies, purified from an EC, to assess the potential impact of polyclonal non-neutralizing antibodies on a stringent SHIV-SF162P3 challenge in rhesus monkeys. Passive transfer of a low-dose of ADCC inducing antibodies did not protect from infection following SHIV-SF162P3 challenge. Passively administered antibody titers and gp120-specific, but not gp41-specific, ADCC and antibody induced phagocytosis (ADCP were detected in the majority of the monkeys, but did not correlate with post infection viral control. Thus these data raise the possibility that gp120-specific ADCC activity alone may not be sufficient to control viremia post infection but that other specificities or Fc-effector profiles, alone or in combination, may have an impact on viral control and should be tested in future passive transfer experiments.

  16. Effective multiple oral administration of reverse genetics engineered infectious bursal disease virus in mice in the presence of neutralizing antibodies.

    Science.gov (United States)

    Hornyák, Ákos; Lipinski, Kai S; Bakonyi, Tamás; Forgách, Petra; Horváth, Ernő; Farsang, Attila; Hedley, Susan J; Palya, Vilmos; Bakács, Tibor; Kovesdi, Imre

    2015-01-01

    Despite spectacular successes in hepatitis B and C therapies, severe hepatic impairment is still a major treatment problem. The clinically tested infectious bursal disease virus (IBDV) superinfection therapy promises an innovative, interferon-free solution to this great unmet need, provided that a consistent manufacturing process preventing mutations or reversions to virulent strains is obtained. To address safety concerns, a tissue culture adapted IBDV vaccine strain V903/78 was cloned into cDNA plasmids ensuring reproducible production of a reverse engineered virus R903/78. The therapeutic drug candidate was characterized by immunocytochemistry assay, virus particle determination and immunoblot analysis. The biodistribution and potential immunogenicity of the IBDV agent was determined in mice, which is not a natural host of this virus, by quantitative detection of IBDV RNA by a quantitative reverse transcriptase-polymerase chain reaction and virus neutralization test, respectively. Several human cell lines supported IBDV propagation in the absence of visible cytopathic effect. The virus was stable from pH 8 to pH 6 and demonstrated significant resistance to low pH and also proved to be highly resistant to high temperatures. No pathological effects were observed in mice. Single and multiple oral administration of IBDV elicited antibodies with neutralizing activities in vitro. Repeat oral administration of R903/78 was successful despite the presence of neutralizing antibodies. Single oral and intravenous administration indicated that IBDV does not replicate in mammalian liver alleviating some safety related concerns. These data supports the development of an orally delivered anti-hepatitis B virus/ anti-hepatitis C virus viral agent for human use. Copyright © 2015 John Wiley & Sons, Ltd.

  17. Prediction of HIV-1 sensitivity to broadly neutralizing antibodies shows a trend towards resistance over time.

    Science.gov (United States)

    Hake, Anna; Pfeifer, Nico

    2017-10-01

    Treatment with broadly neutralizing antibodies (bNAbs) has proven effective against HIV-1 infections in humanized mice, non-human primates, and humans. Due to the high mutation rate of HIV-1, resistance testing of the patient's viral strains to the bNAbs is still inevitable. So far, bNAb resistance can only be tested in expensive and time-consuming neutralization experiments. Here, we introduce well-performing computational models that predict the neutralization response of HIV-1 to bNAbs given only the envelope sequence of the virus. Using non-linear support vector machines based on a string kernel, the models learnt even the important binding sites of bNAbs with more complex epitopes, i.e., the CD4 binding site targeting bNAbs, proving thereby the biological relevance of the models. To increase the interpretability of the models, we additionally provide a new kind of motif logo for each query sequence, visualizing those residues of the test sequence that influenced the prediction outcome the most. Moreover, we predicted the neutralization sensitivity of around 34,000 HIV-1 samples from different time points to a broad range of bNAbs, enabling the first analysis of HIV resistance to bNAbs on a global scale. The analysis showed for many of the bNAbs a trend towards antibody resistance over time, which had previously only been discovered for a small non-representative subset of the global HIV-1 population.

  18. A potent human neutralizing antibody Fc-dependently reduces established HBV infections.

    Science.gov (United States)

    Li, Dan; He, Wenhui; Liu, Ximing; Zheng, Sanduo; Qi, Yonghe; Li, Huiyu; Mao, Fengfeng; Liu, Juan; Sun, Yinyan; Pan, Lijing; Du, Kaixin; Ye, Keqiong; Li, Wenhui; Sui, Jianhua

    2017-09-26

    Hepatitis B virus (HBV) infection is a major global health problem. Currently-available therapies are ineffective in curing chronic HBV infection. HBV and its satellite hepatitis D virus (HDV) infect hepatocytes via binding of the preS1 domain of its large envelope protein to sodium taurocholate cotransporting polypeptide (NTCP). Here, we developed novel human monoclonal antibodies that block the engagement of preS1 with NTCP and neutralize HBV and HDV with high potency. One antibody, 2H5-A14, functions at picomolar level and exhibited neutralization-activity-mediated prophylactic effects. It also acts therapeutically by eliciting antibody-Fc-dependent immunological effector functions that impose durable suppression of viral infection in HBV-infected mice, resulting in reductions in the levels of the small envelope antigen and viral DNA, with no emergence of escape mutants. Our results illustrate a novel antibody-Fc-dependent approach for HBV treatment and suggest 2H5-A14 as a novel clinical candidate for HBV prevention and treatment of chronic HBV infection.

  19. Neutralizing antibody response during human immunodeficiency virus type 1 infection: type and group specificity and viral escape

    DEFF Research Database (Denmark)

    Arendrup, M; Sönnerborg, A; Svennerholm, B

    1993-01-01

    The paradox that group-specific neutralizing antibodies (NA) exist in the majority of human immunodeficiency virus type 1 (HIV-1)-infected patients, whereas the NA response against autologous HIV-1 virus isolates is highly type-specific, motivated us to study the type- and group-specific NA...... demonstrated, suggesting that the majority of the change in neutralization sensitivity is driven by the selective pressure of type-specific NA. Furthermore, no differences were observed in sensitivity to neutralization by anti-carbohydrate neutralizing monoclonal antibodies or the lectin concanavalin A...

  20. Neutral Red versus MTT assay of cell viability in the presence of copper compounds.

    Science.gov (United States)

    Gomez Perez, Mariela; Fourcade, Lyvia; Mateescu, Mircea Alexandru; Paquin, Joanne

    2017-10-15

    Copper is essential for numerous physiological functions, and copper compounds may display therapeutic as well as cytotoxic effects. The MTT (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide) assay is a standard test largely used in cytotoxicity studies. This report shows that low micromolar levels of copper compounds such as Cu(II)Urea 2 , Cu(II)Ser 2 and CuCl 2 can interfere with the MTT assay making improper the detection of formazan product of MTT reduction. Comparatively, the Neutral Red assay appears to be sensitive and showing no interference with these compounds. The lactate dehydrogenase alternative assay cannot be used because of inhibitory effect of these copper compounds on the enzyme activity. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Broadly Neutralizing Antibody Responses in a Large Longitudinal Sub-Saharan HIV Primary Infection Cohort.

    Directory of Open Access Journals (Sweden)

    Elise Landais

    2016-01-01

    Full Text Available Broadly neutralizing antibodies (bnAbs are thought to be a critical component of a protective HIV vaccine. However, designing vaccines immunogens able to elicit bnAbs has proven unsuccessful to date. Understanding the correlates and immunological mechanisms leading to the development of bnAb responses during natural HIV infection is thus critical to the design of a protective vaccine. The IAVI Protocol C program investigates a large longitudinal cohort of primary HIV-1 infection in Eastern and South Africa. Development of neutralization was evaluated in 439 donors using a 6 cross-clade pseudo-virus panel predictive of neutralization breadth on larger panels. About 15% of individuals developed bnAb responses, essentially between year 2 and year 4 of infection. Statistical analyses revealed no influence of gender, age or geographical origin on the development of neutralization breadth. However, cross-clade neutralization strongly correlated with high viral load as well as with low CD4 T cell counts, subtype-C infection and HLA-A*03(- genotype. A correlation with high overall plasma IgG levels and anti-Env IgG binding titers was also found. The latter appeared not associated with higher affinity, suggesting a greater diversity of the anti-Env responses in broad neutralizers. Broadly neutralizing activity targeting glycan-dependent epitopes, largely the N332-glycan epitope region, was detected in nearly half of the broad neutralizers while CD4bs and gp41-MPER bnAb responses were only detected in very few individuals. Together the findings suggest that both viral and host factors are critical for the development of bnAbs and that the HIV Env N332-glycan supersite may be a favorable target for vaccine design.

  2. Immunoradiometric assay for cytomegalovirus-specific IgG antibodies; Assay development and evaluation in blood transfusion practice

    Energy Technology Data Exchange (ETDEWEB)

    Klapper, P.E.; Cleator, G.M.; Prinja-Wolks, D.; Morris, D.J. (Medical School, Manchester (United Kingdom). Department of Medical microbiology, Virology Unit); Morell, G. (Regional Blood Transfusion Centre, manchester (United Kingdom))

    1990-03-01

    An immunoradiometric assay (radio-immunosorbent test; RIST) for the detection of IgG antibodies to human herpesvirus 4 (human cytomegalovirus (CMV)) has been developed. The technique utilizes CMV antigen passively adsorbed to a polyvinyl microtitration plate and a radiolabelled murine monoclonal anti-human IgG antibody to detect binding of human antibody to the 'solid phase' reagent. The assay was optimized, and its specifity confirmed by testing paired acute and convalescent sera from patients with acute CMV or other human herpesvirus infections. To determine the assay's sensitivity 1433 blood donor sera were examined. The RIST was more sensitive than a standard complement fixation (CFT). Use of a monoclonal anti-human IgG antibody in the RIST reduced non-specific binding to the control uninfected cell antigen such that blood donor sera could be tested in the assay using only a CMV antigen without generating an unacceptable false positive rate. (author). 23 refs.; 1 tab.

  3. Solid phase radioimmunoassays using labelled antibodies: a conceptual framework for designing assays

    International Nuclear Information System (INIS)

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

    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 radioimmunoassays (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, the direct 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(>1), and that the formation of the antigen-antibody complex is dependent on the mass action effect

  4. Structural bases of coronavirus attachment to host aminopeptidase N and its inhibition by neutralizing antibodies.

    Directory of Open Access Journals (Sweden)

    Juan Reguera

    Full Text Available The coronaviruses (CoVs are enveloped viruses of animals and humans associated mostly with enteric and respiratory diseases, such as the severe acute respiratory syndrome and 10-20% of all common colds. A subset of CoVs uses the cell surface aminopeptidase N (APN, a membrane-bound metalloprotease, as a cell entry receptor. In these viruses, the envelope spike glycoprotein (S mediates the attachment of the virus particles to APN and subsequent cell entry, which can be blocked by neutralizing antibodies. Here we describe the crystal structures of the receptor-binding domains (RBDs of two closely related CoV strains, transmissible gastroenteritis virus (TGEV and porcine respiratory CoV (PRCV, in complex with their receptor, porcine APN (pAPN, or with a neutralizing antibody. The data provide detailed information on the architecture of the dimeric pAPN ectodomain and its interaction with the CoV S. We show that a protruding receptor-binding edge in the S determines virus-binding specificity for recessed glycan-containing surfaces in the membrane-distal region of the pAPN ectodomain. Comparison of the RBDs of TGEV and PRCV to those of other related CoVs, suggests that the conformation of the S receptor-binding region determines cell entry receptor specificity. Moreover, the receptor-binding edge is a major antigenic determinant in the TGEV envelope S that is targeted by neutralizing antibodies. Our results provide a compelling view on CoV cell entry and immune neutralization, and may aid the design of antivirals or CoV vaccines. APN is also considered a target for cancer therapy and its structure, reported here, could facilitate the development of anti-cancer drugs.

  5. Assay for Serum Antibodies to Infectious Bursal Disease Virus in ...

    African Journals Online (AJOL)

    Infectious bursal disease (IBD) is an acute, lymphocidal disease that has been a threat to poultry production in Nigeria and a major disease problem of poultry producing areas of the world. A serological detection of antibodies to the virus was conducted on 300 sera samples derived from local chickens slaughtered at Sheik ...

  6. Neutralization resistance of hepatitis C virus can be overcome by recombinant human monoclonal antibodies

    DEFF Research Database (Denmark)

    Pedersen, Jannie L; Carlsen, Thomas H R; Prentoe, Jannick

    2013-01-01

    Immunotherapy and vaccine development for hepatitis C virus (HCV) will depend on broadly reactive neutralizing antibodies (NAbs). However, studies in infectious strain JFH1-based culture systems expressing patient-derived Core-NS2 proteins have suggested neutralization resistance for specific HCV...... demonstrated that the novel genotype 2 viruses as well as prototype strains J6/JFH1(2a) and J8/JFH1(2b), all with authentic envelope proteins, were resistant to neutralization by genotype 2a, 2b, 2c, 2j, 2i, and 2q patient sera. However, these patient sera had high titers of HCV-specific NAbs, because...... they efficiently reduced the infectivity of J6(2a) and J8(2b) with deleted hypervariable region 1. The genotype 2a, 2b, and 2c viruses, found resistant to polyclonal patient sera neutralization, were efficiently neutralized by two lead HMAbs (AR4A and HC84.26). Conclusion: Using novel 2a, 2b, and 2c cell...

  7. 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

    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...

  8. Rapid Active Assay for the Detection of Antibodies to West Nile Virus in Chickens

    National Research Council Canada - National Science Library

    Groves, Stephanie S; Turell, Michael J; Bailey, Charles L; Morozov, Victor N

    2008-01-01

    ... by detection of bound IgM molecules with functionalized magnetic beads as active labels. This assay takes only 15 minutes and has the same sensitivity as a commercially available human WNV IgM antibody-capture enzyme-linked immunosorbent assay...

  9. Interference by antiruthenium antibodies in the Roche thyroid-stimulating hormone assay

    NARCIS (Netherlands)

    Buijs, M. M.; Gorgels, J. P. M. C.; Endert, E.

    2011-01-01

    There are many causes of interference in immunoassays causing erratic patient results. A method-specific interference due to antiruthenium antibodies in Roche free thyroxine (fT4) and free triiodothyronine (fT3) assays has been described previously. As a result, a new generation fT4 assay has been

  10. 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...

  11. Neutralizing antibody response in the patients with hand, foot and mouth disease to enterovirus 71 and its clinical implications

    Directory of Open Access Journals (Sweden)

    Zhu Liye

    2011-06-01

    Full Text Available Abstract Enterovirus 71 (EV71 has emerged as a significant pathogen causing large outbreaks in China for the past 3 years. Developing an EV71 vaccine is urgently needed to stop the spread of the disease; however, the adaptive immune response of humans to EV71 infection remains unclear. We examined the neutralizing antibody titers in HFMD patients and compared them to those of asymptomatic healthy children and young adults. We found that 80% of HFMD patients became positive for neutralizing antibodies against EV71 (GMT = 24.3 one day after the onset of illness. The antibody titers in the patients peaked two days (GMT = 79.5 after the illness appeared and were comparable to the level of adults (GMT = 45.2. Noticeably, the antibody response was not correlated with disease severity, suggesting that cellular immune response, besides neutralizing antibodies, could play critical role in controlling the outcome of EV71 infection in humans.

  12. Llama Antibody Fragments Recognizing Various Epitopes of the CD4bs Neutralize a Broad Range of HIV-1 Subtypes A, B and C

    Science.gov (United States)

    Aasa-Chapman, Marlèn; Gorlani, Andrea; Forsman Quigley, Anna; Hulsik, David Lutje; Chen, Lei; Weiss, Robin; de Haard, Hans; Verrips, Theo

    2012-01-01

    Many of the neutralising antibodies, isolated to date, display limited activities against the globally most prevalent HIV-1 subtypes A and C. Therefore, those subtypes are considered to be an important target for antibody-based therapy. Variable domains of llama heavy chain antibodies (VHH) have some superior properties compared with classical antibodies. Therefore we describe the application of trimeric forms of envelope proteins (Env), derived from HIV-1 of subtype A and B/C, for a prolonged immunization of two llamas. A panel of VHH, which interfere with CD4 binding to HIV-1 Env were selected with use of panning. The results of binding and competition assays to various Env, including a variant with a stabilized CD4-binding state (gp120Ds2), cross-competition experiments, maturation analysis and neutralisation assays, enabled us to classify the selected VHH into three groups. The VHH of group I were efficient mainly against viruses of subtype A, C and B′/C. The VHH of group II resemble the broadly neutralising antibody (bnmAb) b12, neutralizing mainly subtype B and C viruses, however some had a broader neutralisation profile. A representative of the third group, 2E7, had an even higher neutralization breadth, neutralizing 21 out of the 26 tested strains belonging to the A, A/G, B, B/C and C subtypes. To evaluate the contribution of certain amino acids to the potency of the VHH a small set of the mutants were constructed. Surprisingly this yielded one mutant with slightly improved neutralisation potency against 92UG37.A9 (subtype A) and 96ZM651.02 (subtype C). These findings and the well-known stability of VHH indicate the potential application of these VHH as anti-HIV-1 microbicides. PMID:22438910

  13. Variables affecting viral plaque formation in microculture plaque assays using homologous antibody in a liquid overlay.

    Science.gov (United States)

    Randhawa, A S; Stanton, G J; Green, J A; Baron, S

    1977-05-01

    A liquid antibody microculture plaque assay and the variables that govern its effectiveness are described. The assay is based on the principle that low concentrations of homologous antibody can inhibit secondary plaque formation without inhibiting formation of primary plaques. Thus, clear plaques that followed a linear dose response were produced. The assay was found to be more rapid, less cumbersome, and less expensive than assays using agar overlays and larger tissue culture plates. It was reproducible, quantitative, and had about the same sensitivity as the agar overlay technique in measuring infectious coxsackievirus type B-3. It was more sensitive in assaying adenovirus type 3 and Western equine encephalomyelitis, vesicular stomatitis, Semliki forest, Sendai, Sindbis, and Newcastle disease viruses than were liquid, carboxymethylcellulose, and methylcellulose microculture plaque assays. The variables influencing sensitivity and accuracy, as determined by using coxsackievirus type B-3, were: (i) the inoculum volume of virus; (ii) the incubation period of virus; and (iii) the incubation temperature.

  14. Neutralizing antibodies against two HIV-1 strains in consecutively collected serum samples: cross neutralization and association to HIV-1 related disease

    DEFF Research Database (Denmark)

    Arendrup, M; Nielsen, C M; Hansen, J E

    1992-01-01

    97 sera collected during a 10-year period from 10 HIV-1 infected individuals were tested for neutralizing capacity against a virus isolate FICPH-22 obtained from a Danish AIDS patient, and the laboratory strain HTLV-IIIB. Three patterns of serum neutralizing activity were demonstrated: (a) patients...... developing high neutralizing activity against both HIV strains; (b) patients developing high neutralizing activity against the Danish virus isolate; and (c) patients developing only low titers of neutralizing antibodies (NA) against both HIV strains. The HTLV-IIIB strain was less sensitive to serum...... neutralization than the FICPH-22 isolate and the appearance of NA against HTLV-IIIB was typically lacking several years behind that against FICPH-22 indicating a broadening of the NA response over time. No difference in clinical outcome was observed comparing patients reaching high titers of NA and patients...

  15. An indirect antibody assay using haptenated antigen and 125I-labelled anti-hapten antibody

    International Nuclear Information System (INIS)

    Aalberse, R.C.; Amsterdam Univ.

    1978-01-01

    Hapten (trinitrophenyl) was coupled to antigen (ovalbumin). The haptenated antigen was bound by anti-ovalbumin antibody and binding was quantitated with 125 I-labelled anti-hapten antibodies. Thus, with a single radioactive reagent, antibodies against a variety of antigens can be detected while the problems inherent in a labelled antiglobulin binding test are avoided. In the ovalbumin system, the haptenated antigen binding test proved to be approximately 20 times as sensitive as the iodinated ovalbumin binding test

  16. 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

    Recent advances in the development of conjugate polysaccharide vaccines for human use have stimulated interest in the use of assays detecting antibody-secreting cells (AbSC) with specificity for bacterial antigens. Here we present improved haemolytic plaque-forming cell (PFC) assays detecting Ab......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 antibodies aggregation of secreted monomeric antibody (IgG) is critical for plaque formation and increases the avidity of binding to target cells....

  17. Human broadly neutralizing antibodies to the envelope glycoprotein complex of hepatitis C virus

    DEFF Research Database (Denmark)

    Giang, Erick; Dorner, Marcus; Prentoe, Jannick C

    2012-01-01

    , and an effective vaccine should target conserved T- and B-cell epitopes of the virus. Conserved B-cell epitopes overlapping the CD81 receptor-binding site (CD81bs) on the E2 viral envelope glycoprotein have been reported previously and provide promising vaccine targets. In this study, we isolated 73 human m......Abs recognizing five distinct antigenic regions on the virus envelope glycoprotein complex E1E2 from an HCV-immune phage-display antibody library by using an exhaustive-panning strategy. Many of these mAbs were broadly neutralizing. In particular, the mAb AR4A, recognizing a discontinuous epitope outside the CD81......bs on the E1E2 complex, has an exceptionally broad neutralizing activity toward diverse HCV genotypes and protects against heterologous HCV challenge in a small animal model. The mAb panel will be useful for the design and development of vaccine candidates to elicit broadly neutralizing antibodies...

  18. Protective efficacy of neutralizing monoclonal antibodies in a nonhuman primate model of Ebola hemorrhagic fever.

    Science.gov (United States)

    Marzi, Andrea; Yoshida, Reiko; Miyamoto, Hiroko; Ishijima, Mari; Suzuki, Yasuhiko; Higuchi, Megumi; Matsuyama, Yukie; Igarashi, Manabu; Nakayama, Eri; Kuroda, Makoto; Saijo, Masayuki; Feldmann, Friederike; Brining, Douglas; Feldmann, Heinz; Takada, Ayato

    2012-01-01

    Ebola virus (EBOV) is the causative agent of severe hemorrhagic fever in primates, with human case fatality rates up to 90%. Today, there is neither a licensed vaccine nor a treatment available for Ebola hemorrhagic fever (EHF). Single monoclonal antibodies (MAbs) specific for Zaire ebolavirus (ZEBOV) have been successfully used in passive immunization experiments in rodent models, but have failed to protect nonhuman primates from lethal disease. In this study, we used two clones of human-mouse chimeric MAbs (ch133 and ch226) with strong neutralizing activity against ZEBOV and evaluated their protective potential in a rhesus macaque model of EHF. Reduced viral loads and partial protection were observed in animals given MAbs ch133 and ch226 combined intravenously at 24 hours before and 24 and 72 hours after challenge. MAbs circulated in the blood of a surviving animal until virus-induced IgG responses were detected. In contrast, serum MAb concentrations decreased to undetectable levels at terminal stages of disease in animals that succumbed to infection, indicating substantial consumption of these antibodies due to virus replication. Accordingly, the rapid decrease of serum MAbs was clearly associated with increased viremia in non-survivors. Our results indicate that EBOV neutralizing antibodies, particularly in combination with other therapeutic strategies, might be beneficial in reducing viral loads and prolonging disease progression during EHF.

  19. Broad neutralizing human monoclonal antibodies against influenza virus from vaccinated healthy donors

    Energy Technology Data Exchange (ETDEWEB)

    Kubota-Koketsu, Ritsuko; Mizuta, Hiroyuki [Department of Virology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871 (Japan); Oshita, Masatoshi; Ideno, Shoji [Osaka Research Laboratory, Benesis Corporation, Yodogawa-ku, Osaka 532-6505 (Japan); Yunoki, Mikihiro [Osaka Research Laboratory, Benesis Corporation, Yodogawa-ku, Osaka 532-6505 (Japan); Department of Virology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871 (Japan); Kuhara, Motoki [Ina Laboratory, Medical and Biological Laboratories Corporation, Ltd., Ina, Nagano 396-0002 (Japan); Yamamoto, Naomasa [Department of Biochemistry, School of Pharmaceutical Sciences, Ohu University, Koriyama, Fukushima 963-8611 (Japan); Okuno, Yoshinobu [Kanonji Institute, The Research Foundation for Microbial Diseases of Osaka University, Kanonji, Kagawa 768-0061 (Japan); Ikuta, Kazuyoshi, E-mail: ikuta@biken.osaka-u.ac.jp [Department of Virology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871 (Japan)

    2009-09-11

    Human monoclonal antibodies (HuMAbs) prepared from patients with viral infections could provide information on human epitopes important for the development of vaccines as well as potential therapeutic applications. Through the fusion of peripheral blood mononuclear cells from a total of five influenza-vaccinated volunteers, with newly developed murine-human chimera fusion partner cells, named SPYMEG, we obtained 10 hybridoma clones stably producing anti-influenza virus antibodies: one for influenza A H1N1, four for influenza A H3N2 and five for influenza B. Surprisingly, most of the HuMAbs showed broad reactivity within subtype and four (two for H3N2 and two for B) showed broad neutralizing ability. Importantly, epitope mapping revealed that the two broad neutralizing antibodies to H3N2 derived from different donors recognized the same epitope located underneath the receptor-binding site of the hemagglutinin globular region that is highly conserved among H3N2 strains.

  20. Protective efficacy of neutralizing monoclonal antibodies in a nonhuman primate model of Ebola hemorrhagic fever.

    Directory of Open Access Journals (Sweden)

    Andrea Marzi

    Full Text Available Ebola virus (EBOV is the causative agent of severe hemorrhagic fever in primates, with human case fatality rates up to 90%. Today, there is neither a licensed vaccine nor a treatment available for Ebola hemorrhagic fever (EHF. Single monoclonal antibodies (MAbs specific for Zaire ebolavirus (ZEBOV have been successfully used in passive immunization experiments in rodent models, but have failed to protect nonhuman primates from lethal disease. In this study, we used two clones of human-mouse chimeric MAbs (ch133 and ch226 with strong neutralizing activity against ZEBOV and evaluated their protective potential in a rhesus macaque model of EHF. Reduced viral loads and partial protection were observed in animals given MAbs ch133 and ch226 combined intravenously at 24 hours before and 24 and 72 hours after challenge. MAbs circulated in the blood of a surviving animal until virus-induced IgG responses were detected. In contrast, serum MAb concentrations decreased to undetectable levels at terminal stages of disease in animals that succumbed to infection, indicating substantial consumption of these antibodies due to virus replication. Accordingly, the rapid decrease of serum MAbs was clearly associated with increased viremia in non-survivors. Our results indicate that EBOV neutralizing antibodies, particularly in combination with other therapeutic strategies, might be beneficial in reducing viral loads and prolonging disease progression during EHF.

  1. Broad neutralizing human monoclonal antibodies against influenza virus from vaccinated healthy donors

    International Nuclear Information System (INIS)

    Kubota-Koketsu, Ritsuko; Mizuta, Hiroyuki; Oshita, Masatoshi; Ideno, Shoji; Yunoki, Mikihiro; Kuhara, Motoki; Yamamoto, Naomasa; Okuno, Yoshinobu; Ikuta, Kazuyoshi

    2009-01-01

    Human monoclonal antibodies (HuMAbs) prepared from patients with viral infections could provide information on human epitopes important for the development of vaccines as well as potential therapeutic applications. Through the fusion of peripheral blood mononuclear cells from a total of five influenza-vaccinated volunteers, with newly developed murine-human chimera fusion partner cells, named SPYMEG, we obtained 10 hybridoma clones stably producing anti-influenza virus antibodies: one for influenza A H1N1, four for influenza A H3N2 and five for influenza B. Surprisingly, most of the HuMAbs showed broad reactivity within subtype and four (two for H3N2 and two for B) showed broad neutralizing ability. Importantly, epitope mapping revealed that the two broad neutralizing antibodies to H3N2 derived from different donors recognized the same epitope located underneath the receptor-binding site of the hemagglutinin globular region that is highly conserved among H3N2 strains.

  2. The Effect of Induced Antibodies with Respect to Neutralization, Clearance Rate and Functional Activity in a Rabbit/Infliximab Model

    DEFF Research Database (Denmark)

    Henriksen, Maiken Lumby; Søgaard Teisner, Ane; Kjeldsen, Jens

    2016-01-01

    BACKGROUND: Therapeutic antibodies are a developing field for treatment of an expanding number of inflammatory diseases, including Crohn's disease. Treatment with monoclonal antibodies is frequently hampered by development of anti-drug antibodies (ADAs) that may compromise the treatment. MATERIALS...... AND METHODS: We addressed this issue in a rabbit model of treatment with the anti-tumor-necrosis factor alpha (TNFα) antibody, infliximab (IFX). We developed an inhibition ELISA to selectively measure absolute concentrations of neutralizing antibodies and another ELISA for measuring the concentration...... of functional IFX in the circulation. RESULTS: We found that the concentration of functional IFX was inversely proportional to the concentration of neutralizing antibodies. CONCLUSION: Administration of IFX to rabbits showed diversity in immune responses/tolerance toward IFX, corresponding to responses observed...

  3. Stoichiometry of monoclonal antibody neutralization of T-cell line-adapted human immunodeficiency virus type 1

    DEFF Research Database (Denmark)

    Schønning, Kristian; Lund, O; Lund, O S

    1999-01-01

    In order to study the stoichiometry of monoclonal antibody (MAb) neutralization of T-cell line-adapted human immunodeficiency virus type 1 (HIV-1) in antibody excess and under equilibrium conditions, we exploited the ability of HIV-1 to generate mixed oligomers when different env genes...

  4. 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. ...... antibodies, require only basic laboratory equipment, are robust, fast, cheap, easy to perform, and readily adapted to automation....

  5. Generation of neutralizing monoclonal antibodies against a conformational epitope of human adenovirus type 7 (HAdv-7 incorporated in capsid encoded in a HAdv-3-based vector.

    Directory of Open Access Journals (Sweden)

    Minglong Liu

    Full Text Available The generation of monoclonal antibodies (MAbs by epitope-based immunization is difficult because the immunogenicity of simple peptides is poor and T cells must be potently stimulated and immunological memory elicited. A strategy in which antigen is incorporated into the adenoviral capsid protein has been used previously to develop antibody responses against several vaccine targets and may offer a solution to this problem. In this study, we used a similar strategy to develop HAdv-7-neutralizing MAbs using rAdMHE3 virions into which hexon hypervariable region 5 (HVR5 of adenovirus type 7 (HAdv-7 was incorporated. The epitope mutant rAdMHE3 was generated by replacing HVR5 of Ad3EGFP, a recombinant HAdv-3-based vector expressing enhanced green fluorescence protein, with HVR5 of HAdv-7. We immunized BALB/c mice with rAdMHE3 virions and produced 22 different MAbs against them, four of which showed neutralizing activity against HAdv-7 in vitro. Using an indirect enzyme-linked immunosorbent assay (ELISA analysis and an antibody-binding-competition ELISA with Ad3EGFP, HAdv-7, and a series of chimeric adenoviral particles containing epitope mutants, we demonstrated that the four MAbs recognize the neutralization site within HVR5 of the HAdv-7 virion. Using an immunoblotting analysis and ELISA with HAdv-7, recombinant peptides, and a synthetic peptide, we also showed that the neutralizing epitope within HVR5 of the HAdv-7 virion is a conformational epitope. These findings suggest that it is feasible to use a strategy in which antigen is incorporated into the adenoviral capsid protein to generate neutralizing MAbs. This strategy may also be useful for developing therapeutic neutralizing MAbs and designing recombinant vector vaccines against HAdv-7, and in structural analysis of adenoviruses.

  6. Solid-phase peptide quantitation assay using labeled monoclonal antibody and glutaraldehyde fixation

    International Nuclear Information System (INIS)

    Kasprzyk, P.G.; Cuttitta, F.; Avis, I.; Nakanishi, Y.; Treston, A.; Wong, H.; Walsh, J.H.; Mulshine, J.L.

    1988-01-01

    A solid-phase radioimmunoassay utilizing iodinated peptide-specific monoclonal antibody as a detection system instead of labeled peptide has been developed. Regional specific monoclonal antibodies to either gastrin-releasing peptide or gastrin were used as models to validate the general application of our modified assay. Conditions for radioactive labeling of the monoclonal antibody were determined to minimize oxidant damage, which compromises the sensitivity of other reported peptide quantitation assays. Pretreatment of 96-well polyvinyl chloride test plates with a 5% glutaraldehyde solution resulted in consistent retention of sufficient target peptide on the solid-phase matrix to allow precise quantitation. This quantitative method is completed within 1 h of peptide solid phasing. Pretreatment of assay plates with glutaraldehyde increased binding of target peptide and maximized antibody binding by optimizing antigen presentation. The hypothesis that glutaraldehyde affects both peptide binding to the plate and orientation of the peptide was confirmed by analysis of several peptide analogs. These studies indicate that peptide binding was mediated through a free amino group leaving the carboxy-terminal portion of the target peptide accessible for antibody binding. It was observed that the length of the peptide also affects the amount of monoclonal antibody that will bind. Under the optimal conditions, results from quantitation of gastrin-releasing peptide in relevant samples agree well with those from previously reported techniques. Thus, we report here a modified microplate assay which may be generally applied for the rapid and sensitive quantitation of peptide hormones

  7. Alterations of HIV-1 envelope phenotype and antibody-mediated neutralization by signal peptide mutations.

    Directory of Open Access Journals (Sweden)

    Chitra Upadhyay

    2018-01-01

    Full Text Available HIV-1 envelope glycoprotein (Env mediates virus attachment and entry into the host cells. Like other membrane-bound and secreted proteins, HIV-1 Env contains at its N terminus a signal peptide (SP that directs the nascent Env to the endoplasmic reticulum (ER where Env synthesis and post-translational modifications take place. SP is cleaved during Env biosynthesis but potentially influences the phenotypic traits of the Env protein. The Env SP sequences of HIV-1 isolates display high sequence variability, and the significance of such variability is unclear. We postulate that changes in the Env SP influence Env transport through the ER-Golgi secretory pathway and Env folding and/or glycosylation that impact on Env incorporation into virions, receptor binding and antibody recognition. We first evaluated the consequences of mutating the charged residues in the Env SP in the context of infectious molecular clone HIV-1 REJO.c/2864. Results show that three different mutations affecting histidine at position 12 affected Env incorporation into virions that correlated with reduction of virus infectivity and DC-SIGN-mediated virus capture and transmission. Mutations at positions 8, 12, and 15 also rendered the virus more resistant to neutralization by monoclonal antibodies against the Env V1V2 region. These mutations affected the oligosaccharide composition of N-glycans as shown by changes in Env reactivity with specific lectins and by mass spectrometry. Increased neutralization resistance and N-glycan composition changes were also observed when analogous mutations were introduced to another HIV-1 strain, JRFL. To the best of our knowledge, this is the first study showing that certain residues in the HIV-1 Env SP can affect virus neutralization sensitivity by modulating oligosaccharide moieties on the Env N-glycans. The HIV-1 Env SP sequences thus may be under selective pressure to balance virus infectiousness with virus resistance to the host antibody

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

    International Nuclear Information System (INIS)

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

    1986-01-01

    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 3 and should be useful for the detection of antibodies to ligand-binding proteins in general

  9. Development of an anti-HIV vaccine eliciting broadly neutralizing antibodies.

    Science.gov (United States)

    Ahmed, Yousuf; Tian, Meijuan; Gao, Yong

    2017-09-12

    The extreme HIV diversity posts a great challenge on development of an effective anti-HIV vaccine. To solve this problem, it is crucial to discover an appropriate immunogens and strategies that are able to prevent the transmission of the diverse viruses that are circulating in the world. Even though there have been a number of broadly neutralizing anti-HIV antibodies (bNAbs) been discovered in recent years, induction of such antibodies to date has only been observed in HIV-1 infection. Here, in this mini review, we review the progress in development of HIV vaccine in eliciting broad immune response, especially production of bNAbs, discuss possible strategies, such as polyvalent sequential vaccination, that facilitates B cell maturation leading to bNAb response.

  10. 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.

  11. IgA and neutralizing antibodies to influenza a virus in human milk: a randomized trial of antenatal influenza immunization.

    Science.gov (United States)

    Schlaudecker, Elizabeth P; Steinhoff, Mark C; Omer, Saad B; McNeal, Monica M; Roy, Eliza; Arifeen, Shams E; Dodd, Caitlin N; Raqib, Rubhana; Breiman, Robert F; Zaman, K

    2013-01-01

    Antenatal immunization of mothers with influenza vaccine increases serum antibodies and reduces the rates of influenza illness in mothers and their infants. We report the effect of antenatal immunization on the levels of specific anti-influenza IgA levels in human breast milk. (ClinicalTrials.gov identifier NCT00142389; http://clinicaltrials.gov/ct2/show/NCT00142389). The Mother's Gift study was a prospective, blinded, randomized controlled trial that assigned 340 pregnant Bangladeshi mothers to receive either trivalent inactivated influenza vaccine, or 23-valent pneumococcal polysaccharide vaccine during the third trimester. We evaluated breast milk at birth, 6 weeks, 6 months, and 12 months, and serum at 10 weeks and 12 months. Milk and serum specimens from 57 subjects were assayed for specific IgA antibody to influenza A/New Caledonia (H1N1) using an enzyme-linked immunosorbent assay (ELISA) and a virus neutralization assay, and for total IgA using ELISA. Influenza-specific IgA levels in breast milk were significantly higher in influenza vaccinees than in pneumococcal controls for at least 6 months postpartum (p = 0.04). Geometric mean concentrations ranged from 8.0 to 91.1 ELISA units/ml in vaccinees, versus 2.3 to 13.7 ELISA units/mL in controls. Virus neutralization titers in milk were 1.2 to 3 fold greater in vaccinees, and correlated with influenza-specific IgA levels (r = 0.86). Greater exclusivity of breastfeeding in the first 6 months of life significantly decreased the expected number of respiratory illness with fever episodes in infants of influenza-vaccinated mothers (p = 0.0042) but not in infants of pneumococcal-vaccinated mothers (p = 0.4154). The sustained high levels of actively produced anti-influenza IgA in breast milk and the decreased infant episodes of respiratory illness with fever suggest that breastfeeding may provide local mucosal protection for the infant for at least 6 months. Studies are needed to determine the

  12. Diagnostic sensitivity of two radio receptor assays (TRAK Assay and TRAK Dyno human) for the detection of TSH receptor antibodies

    International Nuclear Information System (INIS)

    Paunkovic, N.; Paunkovic, J.

    2003-01-01

    Radio receptor assays for the detection of TSH receptor antibodies in serum are typically based on binding the competition of TSH-R antibodies and 125I -labelled-TSH for membrane preparation of thyrocytes (TBII tests). The sensitivity of the available tests utilizing porcine cell membranes was found to be around 80%. A new test (TRAK Dyno human, BRAHMS) utilizes human recombinant TSH receptor and human standard material that is supposed to improve the performance of the test. We have compared the results of these two assays. The sensitivity of the TRAK Assay tested in 356 patients with untreated Grave's disease was found to be 85%, and 97.5% for TRAK Dyno human in 111 newly diagnosed patients. Both tests were performed from the same serum specimen for 60 of the investigated patients. The TRAK Assay was positive in 50 patients (83.2%) and TRAK Dyno human in 59 patients (98.3%). The specificity of the new radio receptor assay was also improved. (author)

  13. A Lateral Flow Protein Microarray for Rapid and Sensitive Antibody Assays

    Directory of Open Access Journals (Sweden)

    Helene Andersson-Svahn

    2011-11-01

    Full Text Available Protein microarrays are useful tools for highly multiplexed determination of presence or levels of clinically relevant biomarkers in human tissues and biofluids. However, such tools have thus far been restricted to laboratory environments. Here, we present a novel 384-plexed easy to use lateral flow protein microarray device capable of sensitive (< 30 ng/mL determination of antigen-specific antibodies in ten minutes of total assay time. Results were developed with gold nanobeads and could be recorded by a cell-phone camera or table top scanner. Excellent accuracy with an area under curve (AUC of 98% was achieved in comparison with an established glass microarray assay for 26 antigen-specific antibodies. We propose that the presented framework could find use in convenient and cost-efficient quality control of antibody production, as well as in providing a platform for multiplexed affinity-based assays in low-resource or mobile settings.

  14. Assay dependence of Brucella antibody prevalence in a declining Alaskan harbor seal (Phoca vitulina population

    Directory of Open Access Journals (Sweden)

    Hueffer Karsten

    2013-01-01

    Full Text Available Abstract Background Brucella is a group of bacteria that causes brucellosis, which can affect population health and reproductive success in many marine mammals. We investigated the serological prevalence of antibodies against Brucella bacteria in a declining harbor seal population in Glacier Bay National Park, Alaska. Results Prevalence ranged from 16 to 74 percent for those tests detecting antibodies, indicating that harbor seals in Glacier Bay have been exposed to Brucella bacteria. However, the actual level of serological prevalence could not be determined because results were strongly assay-dependent. Conclusions This study reinforces the need to carefully consider assay choice when comparing different studies on the prevalence of anti–Brucella antibodies in pinnipeds and further highlights the need for species- or taxon-specific assay validation for both pathogen and host species.

  15. Heparin removal by ecteola-cellulose pre-treatment enables the use of plasma samples for accurate measurement of anti-Yellow fever virus neutralizing antibodies.

    Science.gov (United States)

    Campi-Azevedo, Ana Carolina; Peruhype-Magalhães, Vanessa; Coelho-Dos-Reis, Jordana Grazziela; Costa-Pereira, Christiane; Yamamura, Anna Yoshida; Lima, Sheila Maria Barbosa de; Simões, Marisol; Campos, Fernanda Magalhães Freire; de Castro Zacche Tonini, Aline; Lemos, Elenice Moreira; Brum, Ricardo Cristiano; de Noronha, Tatiana Guimarães; Freire, Marcos Silva; Maia, Maria de Lourdes Sousa; Camacho, Luiz Antônio Bastos; Rios, Maria; Chancey, Caren; Romano, Alessandro; Domingues, Carla Magda; Teixeira-Carvalho, Andréa; Martins-Filho, Olindo Assis

    2017-09-01

    Technological innovations in vaccinology have recently contributed to bring about novel insights for the vaccine-induced immune response. While the current protocols that use peripheral blood samples may provide abundant data, a range of distinct components of whole blood samples are required and the different anticoagulant systems employed may impair some properties of the biological sample and interfere with functional assays. Although the interference of heparin in functional assays for viral neutralizing antibodies such as the functional plaque-reduction neutralization test (PRNT), considered the gold-standard method to assess and monitor the protective immunity induced by the Yellow fever virus (YFV) vaccine, has been well characterized, the development of pre-analytical treatments is still required for the establishment of optimized protocols. The present study intended to optimize and evaluate the performance of pre-analytical treatment of heparin-collected blood samples with ecteola-cellulose (ECT) to provide accurate measurement of anti-YFV neutralizing antibodies, by PRNT. The study was designed in three steps, including: I. Problem statement; II. Pre-analytical steps; III. Analytical steps. Data confirmed the interference of heparin on PRNT reactivity in a dose-responsive fashion. Distinct sets of conditions for ECT pre-treatment were tested to optimize the heparin removal. The optimized protocol was pre-validated to determine the effectiveness of heparin plasma:ECT treatment to restore the PRNT titers as compared to serum samples. The validation and comparative performance was carried out by using a large range of serum vs heparin plasma:ECT 1:2 paired samples obtained from unvaccinated and 17DD-YFV primary vaccinated subjects. Altogether, the findings support the use of heparin plasma:ECT samples for accurate measurement of anti-YFV neutralizing antibodies. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Detection of LGI1 and CASPR2 antibodies with a commercial cell-based assay in patients with very high VGKC-complex antibody levels.

    Science.gov (United States)

    Yeo, T; Chen, Z; Chai, J Y H; Tan, K

    2017-07-15

    The presence of VGKC-complex antibodies, without LGI1/CASPR2 antibodies, as a standalone marker for neurological autoimmunity remains controversial. Additionally, the lack of an unequivocal VGKC-complex antibody cut-off level defining neurological autoimmunity makes it important to test for monospecific antibodies. We aim to determine the performance characteristics of a commercial assay (Euroimmun, Lübeck, Germany) for LGI1/CASPR2 antibody detection in patients with very high VGKC-complex antibody levels and report their clinico-serological associations. We identified 8 patients in our cohort with the highest VGKC-complex antibody levels (median 2663.5pM, range 933-6730pM) with VGKC-complex antibody related syndromes (Group A). Two other groups were identified; 1 group with suspected neuronal surface antibody syndromes and negative for VGKC-complex antibodies (Group B, n=8), and another group with cerebellar ataxia and negative for onconeuronal antibodies (Group C, n=8). Seven out of 8 patients (87.5%) in Group A had LGI1 and/or CASPR2 antibodies. One Group B patient had LGI1 antibodies but was negative on re-testing with a live cell assay. No Group C patients had monospecific antibodies. Inter-rater reliability was high; combining Groups A and B patients, the kappa statistic was 0.87 and 1.0 for LGI1 and CASPR2 antibodies respectively. We demonstrated that a high proportion of patients with very high VGKC-complex antibody levels and relevant clinical syndromes have LGI1 and/or CASPR2 antibodies detected by the commercial assay. Our findings lend support to the use of the assay for rapid and reliable detection of LGI1 and CASPR2 antibodies. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Isolation and characterization of broadly neutralizing human monoclonal antibodies to the e1 glycoprotein of hepatitis C virus

    DEFF Research Database (Denmark)

    Meunier, Jean-Christophe; Russell, Rodney S.; Goossens, Vera

    2008-01-01

    The relative importance of humoral and cellular immunity in the prevention or clearance of hepatitis C virus (HCV) infection is poorly understood. However, there is considerable evidence that neutralizing antibodies are involved in disease control. Here we describe the detailed analysis of human...... monoclonal antibodies (MAbs) directed against HCV glycoprotein E1, which may have the potential to control HCV infection. We have identified two MAbs that can strongly neutralize HCV-pseudotyped particles (HCVpp) bearing the envelope glycoproteins of genotypes 1a, 1b, 4a, 5a, and 6a and less strongly...... neutralize HCVpp bearing the envelope glycoproteins of genotype 2a. Genotype 3a was not neutralized. The epitopes for both MAbs were mapped to the region encompassing amino acids 313 to 327. In addition, robust neutralization was also observed against cell culture-adapted viruses of genotypes 1a and 2a...

  18. Limited naturally occurring escape in broadly neutralizing antibody epitopes in hepatitis C glycoprotein E2 and constrained sequence usage in acute infection

    NARCIS (Netherlands)

    Rodrigo, Chaturaka; Walker, Melanie R.; Leung, Preston; Eltahla, Auda A.; Grebely, Jason; Dore, Gregory J.; Applegate, Tanya; Page, Kimberly; Dwivedi, Sunita; Bruneau, Julie; Morris, Meghan D.; Cox, Andrea L.; Osburn, William; Kim, Arthur Y.; Schinkel, Janke; Shoukry, Naglaa H.; Lauer, Georg M.; Maher, Lisa; Hellard, Margaret; Prins, Maria; Luciani, Fabio; Lloyd, Andrew R.; Bull, Rowena A.

    2017-01-01

    Broadly neutralizing antibodies have been associated with spontaneous clearance of the hepatitis C infection as well as viral persistence by immune escape. Further study of neutralizing antibody epitopes is needed to unravel pathways of resistance to virus neutralization, and to identify conserved

  19. Construction and Characterization of a Humanized Anti-Epstein-Barr Virus gp350 Antibody with Neutralizing Activity in Cell Culture

    Directory of Open Access Journals (Sweden)

    Jerome E. Tanner

    2018-04-01

    Full Text Available Acute Epstein-Barr virus (EBV infection in immunosuppressed transplant patients can give rise to a malignant B-cell proliferation known as post-transplant lymphoproliferative disease (PTLD. The EBV major virion surface glycoprotein (gp350 is a principal target of naturally occurring neutralizing antibodies and is viewed as the best target to prevent acute infection and PTLD in at-risk transplant recipients. We have constructed a humanized (hu version of the murine anti-gp350 neutralizing monoclonal antibody 72a1. The hu72a1 IgG1 antibody displayed no significant anti-mouse activity, recognized both gp350 and its splice variant gp220 as well as a gp350 peptide that was shown to constitute the principal EBV gp350 neutralizing epitope when tested in immunoassays. Hu72a1 antibody blocked in vitro EBV infection of B cells at a level which equaled that of a mouse-human chimeric 72a1 antibody construct. This work provides a further structural and immunological understanding of the 72a1 antibody interaction with EBV gp350, and constitutes a launch point for future anti-EBV therapeutic antibodies designed to block EBV infection and prevent PTLD while eliminating the deleterious antigenic murine features of the original 72a1 antibody.

  20. [What EIA assay levels correspond to rubella antibody HI assay titer?].

    Science.gov (United States)

    Terada, Kihei; Inoue, Mika; Wakabayashi, Tokio; Ogita, Satoko; Ouchi, Kazunobu

    2009-01-01

    In 2004, a Japanese-government-supported research group recommended that women without rubella antibody or with low titers or = 15 IU/mL), 98.1% (positive > or = 10 IU/mL), and 93.4%, using the kit from Dade Behring Co. Between HI titers and EIA-IgG measured with the Denka kit, the coefficient index was 0.715 (p or = 4.0) from Denka, and to 30 IU/mL with the kit from Dade. EIA-IgG levels > or = 10 IU/mL are considered globally as protective antibody titers, meaning that the Japanese recommendation of < or = 1:16 for vaccination is too loose. Japanese EIA kit values for the rubella antibody should also be expressed in IU/mL using the global standard.

  1. Crystal structure and size-dependent neutralization properties of HK20, a human monoclonal antibody binding to the highly conserved heptad repeat 1 of gp41.

    Directory of Open Access Journals (Sweden)

    Charles Sabin

    Full Text Available The human monoclonal antibody (mAb HK20 neutralizes a broad spectrum of primary HIV-1 isolates by targeting the highly conserved heptad repeat 1 (HR1 of gp41, which is transiently exposed during HIV-1 entry. Here we present the crystal structure of the HK20 Fab in complex with a gp41 mimetic 5-Helix at 2.3 Å resolution. HK20 employs its heavy chain CDR H2 and H3 loops to bind into a conserved hydrophobic HR1 pocket that is occupied by HR2 residues in the gp41 post fusion conformation. Compared to the previously described HR1-specific mAb D5, HK20 approaches its epitope with a different angle which might favor epitope access and thus contribute to its higher neutralization breadth and potency. Comparison of the neutralization activities of HK20 IgG, Fab and scFv employing both single cycle and multiple cycle neutralization assays revealed much higher potencies for the smaller Fab and scFv over IgG, implying that the target site is difficult to access for complete antibodies. Nevertheless, two thirds of sera from HIV-1 infected individuals contain significant titers of HK20-inhibiting antibodies. The breadth of neutralization of primary isolates across all clades, the higher potencies for C-clade viruses and the targeting of a distinct site as compared to the fusion inhibitor T-20 demonstrate the potential of HK20 scFv as a therapeutic tool.

  2. A camelid single-domain antibody neutralizes botulinum neurotoxin A by blocking host receptor binding

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Guorui; Lam, Kwok-ho; Weisemann, Jasmin; Peng, Lisheng; Krez, Nadja; Perry, Kay; Shoemaker, Charles B.; Dong, Min; Rummel, Andreas; Jin, Rongsheng (BCH); (Cornell); (Tufts CTSI); (UCI); (MHH)

    2017-08-07

    Antibody treatment is currently the only available countermeasure for botulism, a fatal illness caused by flaccid paralysis of muscles due to botulinum neurotoxin (BoNT) intoxication. Among the seven major serotypes of BoNT/A-G, BoNT/A poses the most serious threat to humans because of its high potency and long duration of action. Prior to entering neurons and blocking neurotransmitter release, BoNT/A recognizes motoneurons via a dual-receptor binding process in which it engages both the neuron surface polysialoganglioside (PSG) and synaptic vesicle glycoprotein 2 (SV2). Previously, we identified a potent neutralizing antitoxin against BoNT/A1 termed ciA-C2, derived from a camelid heavy-chain-only antibody (VHH). In this study, we demonstrate that ciA-C2 prevents BoNT/A1 intoxication by inhibiting its binding to neuronal receptor SV2. Furthermore, we determined the crystal structure of ciA-C2 in complex with the receptor-binding domain of BoNT/A1 (HCA1) at 1.68 Å resolution. The structure revealed that ciA-C2 partially occupies the SV2-binding site on HCA1, causing direct interference of HCA1 interaction with both the N-glycan and peptide-moiety of SV2. Interestingly, this neutralization mechanism is similar to that of a monoclonal antibody in clinical trials, despite that ciA-C2 is more than 10-times smaller. Taken together, these results enlighten our understanding of BoNT/A1 interactions with its neuronal receptor, and further demonstrate that inhibiting toxin binding to the host receptor is an efficient countermeasure strategy.

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

    Science.gov (United States)

    Bergmann, S M; Wang, Q; Zeng, W; Li, Y; Wang, Y; Matras, M; Reichert, M; Fichtner, D; Lenk, M; Morin, T; Olesen, N J; Skall, H F; Lee, P-Y; Zheng, S; Monaghan, S; Reiche, S; Fuchs, W; Kotler, M; Way, K; Bräuer, G; Böttcher, K; Kappe, A; Kielpinska, J

    2017-11-01

    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 fully validated for KHV. Therefore, it was developed and validated an enzyme-linked immunosorbent assay (ELISA) to detect KHV antibodies. The assay was optimized with respect to plates, buffers, antigens and assay conditions. It demonstrated high diagnostic and analytical sensitivity and specificity 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. © 2017 John Wiley & Sons Ltd.

  4. Characterization of a Large Panel of Rabbit Monoclonal Antibodies against HIV-1 gp120 and Isolation of Novel Neutralizing Antibodies against the V3 Loop.

    Directory of Open Access Journals (Sweden)

    Yali Qin

    Full Text Available We recently reported the induction of potent, cross-clade neutralizing antibodies (nAbs against Human Immunodeficiency Virus type-1 (HIV-1 in rabbits using gp120 based on an M-group consensus sequence. To better characterize these antibodies, 93 hybridomas were generated, which represent the largest panel of monoclonal antibodies (mAbs ever generated from a vaccinated rabbit. The single most frequently recognized epitope of the isolated mAbs was at the very C-terminal end of the protein (APTKAKRRVVEREKR, followed by the V3 loop. A total of seven anti-V3 loop mAbs were isolated, two of which (10A3 and 10A37 exhibited neutralizing activity. In contrast to 10A3 and most other anti-V3 loop nAbs, 10A37 was atypical with its epitope positioned more towards the C-terminal half of the loop. To our knowledge, 10A37 is the most potent and broadly neutralizing anti-V3 loop mAb induced by vaccination. Interestingly, all seven anti-V3 loop mAbs competed with PGT121, suggesting a possibility that early induction of potent anti-V3 loop antibodies could prevent induction of more broadly neutralizing PGT121-like antibodies that target the conserved base of the V3 loop stem.

  5. Somatic populations of PGT135-137 HIV-1-neutralizing antibodies identified by 454 pyrosequencing and bioinformatics

    Directory of Open Access Journals (Sweden)

    Jiang eZhu

    2012-09-01

    Full Text Available Select HIV-1-infected individuals develop sera capable of neutralizing diverse viral strains. The molecular basis of this neutralization is currently being deciphered by the isolation of HIV-1-neutralizing antibodies. In one infected donor, three neutralizing antibodies, PGT135-137, were identified by assessment of neutralization from individually sorted B cells and found to recognize an epitope containing an N-linked glycan at residue 332 on HIV-1 gp120. Here we use deep sequencing and bioinformatics methods to interrogate the B cell record of this donor to gain a more complete understanding of the humoral immune response. PGT135-137-gene family-specific primers were used to amplify heavy and light chain-variable domain sequences. 454 pyrosequencing produced 141,298 heavy-chain sequences of IGHV4-39 origin and 87,229 light-chain sequences of IGKV3-15 origin. A number of heavy and light chain sequences of ~90% identity to PGT137, several to PGT136, and none of high identity to PGT135 were identified. After expansion of these sequences to include close phylogenetic relatives, a total of 202 heavy-chain sequences and 72 light-chain sequences were identified. These sequences were clustered into populations of 95% identity comprising 15 for heavy chain and 10 for light chain, and a select sequence from each population was synthesized and reconstituted with a PGT137-partner chain. Reconstituted antibodies showed varied neutralization phenotypes for HIV-1 clade A and D isolates. Sequence diversity of the antibody population represented by these tested sequences was notably higher than observed with a 454 pyrosequencing-control analysis on 10 antibodies of defined sequence, suggesting that this diversity results primarily from somatic maturation. Our results thus provide an example of how pathogens like HIV-1 are opposed by a varied humoral immune response, derived from intrinsic mechanisms of antibody development, and embodied by somatic populations

  6. A Simple and Sensitive High-Content Assay for the Characterization of Antiproliferative Therapeutic Antibodies.

    Science.gov (United States)

    Stengl, Andreas; Hörl, David; Leonhardt, Heinrich; Helma, Jonas

    2017-03-01

    Monoclonal antibodies (mAbs) have become a central class of therapeutic agents in particular as antiproliferative compounds. Their often complex modes of action require sensitive assays during early, functional characterization. Current cell-based proliferation assays often detect metabolites that are indicative of metabolic activity but do not directly account for cell proliferation. Measuring DNA replication by incorporation of base analogues such as 5-bromo-2'-deoxyuridine (BrdU) fills this analytical gap but was previously restricted to bulk effect characterization in enzyme-linked immunosorbent assay formats. Here, we describe a cell-based assay format for the characterization of antiproliferative mAbs regarding potency and mode of action in a single experiment. The assay makes use of single cell-based high-content-analysis (HCA) for the reliable quantification of replicating cells and DNA content via 5-ethynyl-2'-deoxyuridine (EdU) and 4',6-diamidino-2-phenylindole (DAPI), respectively, as sensitive measures of antiproliferative mAb activity. We used trastuzumab, an antiproliferative therapeutic antibody interfering with HER2 cell surface receptor-mediated growth signal transduction, and HER2-overexpressing cell lines BT474 and SKBR3 to demonstrate up to 10-fold signal-to-background (S/B) ratios for treated versus untreated cells and a shift in cell cycle profiles indicating antibody-induced cell cycle arrest. The assay is simple, cost-effective, and sensitive, providing a cell-based format for preclinical characterization of therapeutic mAbs.

  7. The effects of variations in the specificities of the antibody components on a two-site immunoradiometric assay for ferritin

    International Nuclear Information System (INIS)

    Cowan, S.I.; Stagg, B.H.; Niemann, E.

    1977-01-01

    Variations in the sub-unit antigenic structure of ferritins derived from various human tissues are reflected in the differing specificities of antisera raised against these ferritin preparations. In this study it was shown that antibody specificity played an important role in determining the sensitivity and overall binding of labelled antibody in a two-site immunoradiometric assay for ferritin. Homologous assay systems, in which solid phase and radiolabelled antibodies were of similar specificities, were generally less sensitive and showed lower binding than heterologous assay systems, in which solid phase and labelled antibodies were of different specificities. The source of the ferritin which was used as assay standard also played an important part in determining the sensitivity and overall binding in homologous antibody systems, spleen ferritin standards yielding assays superior to those obtained with placenta or liver ferritin standards. However, these differences between standards were not seen in a heterologous system employing solid phase antibodies directed against liver ferritin and labelled antibodies directed against placenta ferritin. The nature of the ferritin used to prepare immunoadsorbant for the purification of antibodies prior to radioiodination also affected the assay characteristics; antibodies prepared on spleen ferritin immunoadsorbant being more reactive than antibodies prepared on placenta ferritin immunoadsorbant, which in turn were more reactive then antibodies prepared on liver ferritin immunoadsorbant. (orig.) [de

  8. Characterization of monoclonal antibodies against human thyrotropin and use in an immunoradiometric assay and immunohistochemistry

    International Nuclear Information System (INIS)

    Benkirane, M.; Bon, D.; Bellot, F.; Prince, P.; Delori, P.; Hassoun, J.; Carayon, P.

    1987-01-01

    Monoclonal antibodies were prepared against human thyrotropin. 13 different antibodies were characterized. Ten antibodies were of the IgG1 subclass. The affinities of the antibodies were in the range 10 9 -10 11 mol -1 .l. Four of them were specific for hTSH and did not react with hLH, hFSH, hCG or αhCG. Four reacted with these hormones and recognized the α subunit of hCG. One cross-reacted only with HFSH. The remaining four antibodies recognized the holo-hTSH only, and thus were designated as anti-conformational determinants. Monoclonal antibodies reacting with different antigenic determinants on the hTSH molecule defined seven clusters. Two of them were used to develop a simplified two-site sandwich radioimmunoassay in which one monoclonal antibody was immobilized on tubes (anti-βTSH) and another (anti-α) labelled with 125 I. This assay was highly specific and demonstrated a sensitivity level of 0.1 μIU/ml. Two monoclonal antibodies were used in immunohistochemistry and their quality and specificity was assessed in the detection of hTSH immunoreactivity in human pituitary biological sections. 20 refs.; 6 figs.; 2 tabs

  9. Cloning of the first human anti-JCPyV/VP1 neutralizing monoclonal antibody: epitope definition and implications in risk stratification of patients under natalizumab therapy.

    Science.gov (United States)

    Diotti, Roberta Antonia; Mancini, Nicasio; Clementi, Nicola; Sautto, Giuseppe; Moreno, Guisella Janett; Criscuolo, Elena; Cappelletti, Francesca; Man, Petr; Forest, Eric; Remy, Louise; Giannecchini, Simone; Clementi, Massimo; Burioni, Roberto

    2014-08-01

    JC virus (JCPyV) has gained novel clinical importance as cause of progressive multifocal leukoencephalopathy (PML), a rare demyelinating disease recently associated to immunomodulatory drugs, such as natalizumab used in multiple sclerosis (MS) cases. Little is known about the mechanisms leading to PML, and this makes the need of PML risk stratification among natalizumab-treated patients very compelling. Clinical and laboratory-based risk-stratification markers have been proposed, one of these is represented by the JCPyV-seropositive status, which includes about 54% of MS patients. We recently proposed to investigate the possible protective role of neutralizing humoral immune response in preventing JCPyV reactivation. In this proof-of-concept study, by cloning the first human monoclonal antibody (GRE1) directed against a neutralizing epitope on JCPyV/VP1, we optimized a robust anti-JCPyV neutralization assay. This allowed us to evaluate the neutralizing activity in JCPyV-positive sera from MS patients, demonstrating the lack of correlation between the level of anti-JCPyV antibody and anti-JCPyV neutralizing activity. Relevant consequences may derive from future clinical studies induced by these findings; indeed the study of the serum anti-JCPyV neutralizing activity could allow not only a better risk stratification of the patients during natalizumab treatment, but also a better understanding of the pathophysiological mechanisms leading to PML, highlighting the contribution of peripheral versus central nervous system JCPyV reactivation. Noteworthy, the availability of GRE1 could allow the design of novel immunoprophylactic strategies during the immunomodulatory treatment. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. A human monoclonal antibody with neutralizing activity against highly divergent influenza subtypes.

    Directory of Open Access Journals (Sweden)

    Nicola Clementi

    Full Text Available The interest in broad-range anti-influenza A monoclonal antibodies (mAbs has recently been strengthened by the identification of anti-hemagglutinin (HA mAbs endowed with heterosubtypic neutralizing activity to be used in the design of "universal" prophylactic or therapeutic tools. However, the majority of the single mAbs described to date do not bind and neutralize viral isolates belonging to highly divergent subtypes clustering into the two different HA-based influenza phylogenetic groups: the group 1 including, among others, subtypes H1, H2, H5 and H9 and the group 2 including, among others, H3 subtype. Here, we describe a human mAb, named PN-SIA28, capable of binding and neutralizing all tested isolates belonging to phylogenetic group 1, including H1N1, H2N2, H5N1 and H9N2 subtypes and several isolates belonging to group 2, including H3N2 isolates from the first period of the 1968 pandemic. Therefore, PN-SIA28 is capable of neutralizing isolates belonging to subtypes responsible of all the reported pandemics, as well as other subtypes with pandemic potential. The region recognized by PN-SIA28 has been identified on the stem region of HA and includes residues highly conserved among the different influenza subtypes. A deep characterization of PN-SIA28 features may represent a useful help in the improvement of available anti-influenza therapeutic strategies and can provide new tools for the development of universal vaccinal strategies.

  11. Humanization and characterization of an anti-ricin neutralization monoclonal antibody.

    Directory of Open Access Journals (Sweden)

    Wei-Gang Hu

    Full Text Available Ricin is regarded as a high terrorist risk for the public due to its high toxicity and ease of production. Currently, there is no therapeutic or vaccine available against ricin. D9, a murine monoclonal antibody developed previously in our laboratory, can strongly neutralize ricin and is therefore a good candidate for humanization. Humanization of D9 variable regions was achieved by a complementarity-determining region grafting approach. The humanized D9 (hD9 variable regions were further grafted onto human heavy and light chain constant regions to assemble the complete antibody gene. A foot-and-mouth-disease virus-derived 2A self-processing sequence was introduced between heavy and light chain DNA sequences to cleave the recombinant protein into a functional full-length antibody molecule from a single open reading frame driven by a single promoter in an adenoviral vector. After expression in mammalian cells and purification, the hD9 was demonstrated to have equimolar expression of the full-length antibody heavy and light chains. More importantly, the hD9 exhibited high affinity to ricin with K(D of 1.63 nM, comparable to its parental murine D9 (2.55 nM. In a mouse model, intraperitoneal (i.p. administration of hD9, at a low dose of 5 µg per mouse, 4 hours after the i.p. challenge with 5×LD50 ricin was found to rescue 100% of the mice. In addition, administered 6 hours post-challenge, hD9 could still rescue 50% of the mice. The hD9 has the potential to be used for prophylactic or therapeutic purposes against ricin poisoning.

  12. Immunoradiometric assay for quantification of serum antibodies to dental plaque antigen in immunized dogs

    International Nuclear Information System (INIS)

    Ahlstedt, S.; Rylander, H.

    1975-01-01

    An immunoradiometric assay (IRMA) was used for quantifying dog serum antibodies to antigens from dental plaque collected from full-grown dogs. The antigens were adsorbed onto the inner surface of plastic tubes and then incubated with dog-anti-plaque serum, 125 I-labelled anti-dog plasma-immunoglobulin was used for quantification of the specific antibodies. Four 10 months old Beagle dogs in excellent gingival health were immunized for 10 weeks with ultrasonicated dog dental plaque. The antibody levels in antisera sampled 6, 8, 10 and 11 weeks after the first antigen injection were 2 to 5 times as high as those recorded before the immunizing period. The variability of the assay as judged from the difference between duplicate samples was found to be 18 percent+-4 (p<0.01) of the mean value and the variability between the same serum ran on different test occasions 13 percent+-7 (p<0.01). The specificity of the antigen-antibody reaction in the immuno assay was tested by inhibition experiments. Preincubation of the antisera with dental plaque antigen significantly inhibited the antigen-antibody reaction in the IRMA, while bovine serum albumin did not. (author)

  13. Immunoradiometric assay for quantification of serum antibodies to dental plaque antigen in immunized dogs

    Energy Technology Data Exchange (ETDEWEB)

    Ahlstedt, S; Rylander, H [Goeteborg Univ. (Sweden)

    1975-01-01

    An immunoradiometric assay (IRMA) was used for quantifying dog serum antibodies to antigens from dental plaque collected from full-grown dogs. The antigens were adsorbed onto the inner surface of plastic tubes and then incubated with dog-anti-plaque serum, /sup 125/I-labelled anti-dog plasma-immunoglobulin was used for quantification of the specific antibodies. Four 10 months old Beagle dogs in excellent gingival health were immunized for 10 weeks with ultrasonicated dog dental plaque. The antibody levels in antisera sampled 6, 8, 10 and 11 weeks after the first antigen injection were 2 to 5 times as high as those recorded before the immunizing period. The variability of the assay as judged from the difference between duplicate samples was found to be 18 percent+-4 (p<0.01) of the mean value and the variability between the same serum ran on different test occasions 13 percent+-7 (p<0.01). The specificity of the antigen-antibody reaction in the immuno assay was tested by inhibition experiments. Preincubation of the antisera with dental plaque antigen significantly inhibited the antigen-antibody reaction in the IRMA, while bovine serum albumin did not.

  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. 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.

  16. Development of a dipstick assay for detection of Leishmania-specific canine antibodies

    NARCIS (Netherlands)

    Schallig, Henk D. F. H.; Cardoso, Luís; Hommers, Marieke; Kroon, Nel; Belling, Guus; Rodrigues, Manuela; Semião-Santos, Saul J.; Vetter, Hans

    2004-01-01

    A dipstick assay, based on Leishmania infantum antigen, for the rapid detection of Leishmania-specific antibodies in canine serum samples was developed and evaluated. After determination of optimal dipstick test conditions, test performance was compared with two existing serological tests, i.e., the

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

    Science.gov (United States)

    1990-01-01

    stemic antibody titers to ".actinomycetemcornitans, B.gingivalis, Cochracea, and Eubacterium saburreum either de(., cased or remained similar to...1984b) Serological identification of oral Bacteroides spp . by enzyme-linked immunosorbent assay. J. Clin. Microbiol. 19: 639-644. Ebersole, J.L

  18. Single-dilution enzyme-linked immunosorbent assay for quantification of antigen-specific salmonid antibody

    Science.gov (United States)

    Alcorn, S.W.; Pascho, R.J.

    2000-01-01

    An enzyme-linked immunosorbent assay (ELISA) was developed on the basis of testing a single dilution of serum to quantify the level of antibody to the p57 protein of Renibaclerium salmoninarum in sockeye salmon (Oncorhynchus nerka). The levels of antibody were interpolated from a standard curve constructed by relating the optical densities (OD) produced by several dilutions of a high-titer rainbow trout (O. mykiss) antiserum to the p57 protein. The ELISA OD values produced by as many as 36 test sera on each microplate were compared with the standard curve to calculate the antigen-specific antibody activity. Repeated measurements of 36 samples on 3 microplates on each of 6 assay dates indicated that the mean intraassay coefficient of variation (CV) was 6.68% (range, 0-23%) and the mean interassay CV was 8.29% (range, 4-16%). The antibody levels determined for the serum sample from 24 sockeye salmon vaccinated with a recombinant p57 protein generally were correlated with the levels determined by endpoint titration (r2 = 0.936) and with results from another ELISA that was based on extrapolation of antibody levels from a standard curve (r2 = 0.956). The single-dilution antibody ELISA described here increases the number of samples that can be tested on each microplate compared with immunoassays based on analysis of several dilutions of each test serum. It includes controls for interassay standardization and can be used to test fish weighing <3 g.

  19. Human monoclonal antibodies derived from a patient infected with 2009 pandemic influenza A virus broadly cross-neutralize group 1 influenza viruses

    International Nuclear Information System (INIS)

    Pan, Yang; Sasaki, Tadahiro; Kubota-Koketsu, Ritsuko; Inoue, Yuji; Yasugi, Mayo; Yamashita, Akifumi; Ramadhany, Ririn; Arai, Yasuha; Du, Anariwa; Boonsathorn, Naphatsawan; Ibrahim, Madiha S.

    2014-01-01

    Highlights: • Influenza infection can elicit heterosubtypic antibodies to group 1 influenza virus. • Three human monoclonal antibodies were generated from an H1N1-infected patient. • The antibodies predominantly recognized α-helical stem of viral hemagglutinin (HA). • The antibodies inhibited HA structural activation during the fusion process. • The antibodies are potential candidates for future antibody therapy to influenza. - Abstract: Influenza viruses are a continuous threat to human public health because of their ability to evolve rapidly through genetic drift and reassortment. Three human monoclonal antibodies (HuMAbs) were generated in this study, 1H11, 2H5 and 5G2, and they cross-neutralize a diverse range of group 1 influenza A viruses, including seasonal H1N1, 2009 pandemic H1N1 (H1N1pdm) and avian H5N1 and H9N2. The three HuMAbs were prepared by fusing peripheral blood lymphocytes from an H1N1pdm-infected patient with a newly developed fusion partner cell line, SPYMEG. All the HuMAbs had little hemagglutination inhibition activity but had strong membrane-fusion inhibition activity against influenza viruses. A protease digestion assay showed the HuMAbs targeted commonly a short α-helix region in the stalk of the hemagglutinin. Furthermore, Ile45Phe and Glu47Gly double substitutions in the α-helix region made the HA unrecognizable by the HuMAbs. These two amino acid residues are highly conserved in the HAs of H1N1, H5N1 and H9N2 viruses. The HuMAbs reported here may be potential candidates for the development of therapeutic antibodies against group 1 influenza viruses

  20. Human monoclonal antibodies derived from a patient infected with 2009 pandemic influenza A virus broadly cross-neutralize group 1 influenza viruses

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Yang [Research Institute for Microbial Diseases, Osaka University, Suita, Osaka (Japan); Sasaki, Tadahiro [Research Institute for Microbial Diseases, Osaka University, Suita, Osaka (Japan); JST/JICA, Science and Technology Research Partnership for Sustainable Development (SATREPS), Tokyo (Japan); Kubota-Koketsu, Ritsuko [Research Institute for Microbial Diseases, Osaka University, Suita, Osaka (Japan); Kanonji Institute, The Research Foundation for Microbial Diseases of Osaka University, Kanonji, Kagawa (Japan); JST/JICA, Science and Technology Research Partnership for Sustainable Development (SATREPS), Tokyo (Japan); Inoue, Yuji [Research Institute for Microbial Diseases, Osaka University, Suita, Osaka (Japan); JST/JICA, Science and Technology Research Partnership for Sustainable Development (SATREPS), Tokyo (Japan); Yasugi, Mayo [Research Institute for Microbial Diseases, Osaka University, Suita, Osaka (Japan); Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka (Japan); JST/JICA, Science and Technology Research Partnership for Sustainable Development (SATREPS), Tokyo (Japan); Yamashita, Akifumi; Ramadhany, Ririn; Arai, Yasuha [Research Institute for Microbial Diseases, Osaka University, Suita, Osaka (Japan); Du, Anariwa [Research Institute for Microbial Diseases, Osaka University, Suita, Osaka (Japan); JST/JICA, Science and Technology Research Partnership for Sustainable Development (SATREPS), Tokyo (Japan); Boonsathorn, Naphatsawan [Research Institute for Microbial Diseases, Osaka University, Suita, Osaka (Japan); Department of Medical Sciences, Ministry of Public Health, Muang, Nonthaburi (Thailand); JST/JICA, Science and Technology Research Partnership for Sustainable Development (SATREPS), Tokyo (Japan); Ibrahim, Madiha S. [Research Institute for Microbial Diseases, Osaka University, Suita, Osaka (Japan); Department of Microbiology and Immunology, Faculty of Veterinary Medicine, Damanhour University, Damanhour (Egypt); and others

    2014-07-18

    Highlights: • Influenza infection can elicit heterosubtypic antibodies to group 1 influenza virus. • Three human monoclonal antibodies were generated from an H1N1-infected patient. • The antibodies predominantly recognized α-helical stem of viral hemagglutinin (HA). • The antibodies inhibited HA structural activation during the fusion process. • The antibodies are potential candidates for future antibody therapy to influenza. - Abstract: Influenza viruses are a continuous threat to human public health because of their ability to evolve rapidly through genetic drift and reassortment. Three human monoclonal antibodies (HuMAbs) were generated in this study, 1H11, 2H5 and 5G2, and they cross-neutralize a diverse range of group 1 influenza A viruses, including seasonal H1N1, 2009 pandemic H1N1 (H1N1pdm) and avian H5N1 and H9N2. The three HuMAbs were prepared by fusing peripheral blood lymphocytes from an H1N1pdm-infected patient with a newly developed fusion partner cell line, SPYMEG. All the HuMAbs had little hemagglutination inhibition activity but had strong membrane-fusion inhibition activity against influenza viruses. A protease digestion assay showed the HuMAbs targeted commonly a short α-helix region in the stalk of the hemagglutinin. Furthermore, Ile45Phe and Glu47Gly double substitutions in the α-helix region made the HA unrecognizable by the HuMAbs. These two amino acid residues are highly conserved in the HAs of H1N1, H5N1 and H9N2 viruses. The HuMAbs reported here may be potential candidates for the development of therapeutic antibodies against group 1 influenza viruses.

  1. Neutralization of feline immunodeficiency virus by polyclonal cat antibody: Simultaneous involvement of hypervariable regions 4 and 5 of the surface glycoprotein.

    NARCIS (Netherlands)

    C.H.J. Siebelink (Kees); W. Huisman (Willem); J.A. Karlas (Jos); G.F. Rimmelzwaan (Guus); M.L. Bosch (Marnix); A.D.M.E. Osterhaus (Albert)

    1995-01-01

    textabstractSites involved in antibody-mediated neutralization of feline immunodeficiency virus were mapped by reciprocal exchange of envelope fragments or amino acids between molecular clones of feline immunodeficiency virus with different susceptibilities to neutralization by a polyclonal cat

  2. Evaluation of performance of human immunodeficiency virus antigen/antibody combination assays in Taiwan.

    Science.gov (United States)

    Chang, Chun-Kai; Kao, Cheng-Feng; Lin, Pi-Han; Huang, Hui-Lin; Ho, Shu-Yuan; Wong, Kuo-Chen; Lin, Bo-Chang; Yeh, Chang-Ching; Lee, Chia-Yeh; Kao, Chuan-Liang; Lee, Chun-Nan; Chang, Sui-Yuan; Yang, Jyh-Yuan

    2017-08-01

    The fourth-generation human immunodeficiency virus (HIV) combination assay, which can simultaneously detect the presence of anti-HIV antibody and HIV antigen, has been shown to shorten the window period in HIV diagnosis compared with the third-generation HIV antibody immunoassay. This study was aimed to determine the performance of HIV combination assays in Taiwan, where the HIV-1 seroprevalence is 0.007% and HIV-2 infection has never been reported. Performance of three fourth-generation HIV Ag/Ab combination assays (Dia.Pro, Wantai, and Bio-Rad) and one third-generation HIV Ab immunoassay (AxSYM HIV 1/2 gO) was assessed. A total of 152 specimens, including 86 confirmed HIV-seropositive and 66 HIV-seronegative samples, were used in the study. The sensitivity of four assays varied from 98.8% to 100%, and specificity varied from 98.5% to 100%. Performance of the 75 equivocal samples, the HIV status of which was confirmed later, in terms of negative prediction varied from 81.8% to 87.5%. The Bio-Rad and Dia.Pro assays exhibited higher sensitivity for the detection of p24 antigen among the three fourth-generation HIV combination assays. The three fourth-generation HIV Ag/Ab combination assays exhibited better sensitivity, specificity, and negative prediction than the third-generation HIV Ab immunoassay. Copyright © 2015. Published by Elsevier B.V.

  3. Applying antibody-sensitive hypervariable region 1-deleted hepatitis C virus to the study of escape pathways of neutralizing human monoclonal antibody AR5A

    DEFF Research Database (Denmark)

    Velazquez-Moctezuma, Rodrigo; Law, Mansun; Bukh, Jens

    2017-01-01

    Hepatitis C virus (HCV) is a major cause of end-stage liver diseases. With 3–4 million new HCV infections yearly, a vaccine is urgently needed. A better understanding of virus escape from neutralizing antibodies and their corresponding epitopes are important for this effort. However, for viral is...

  4. 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

    Mucin-1 (MUC1) is a heavily O-glycosylated, transmembrane protein that is expressed on the apical surface of most secretory epithelia. In malignantly transformed epithelia, MUC1 has lost its apical distribution, is underglycosylated and is secreted into the circulation. Due to the underglycosylat......Mucin-1 (MUC1) is a heavily O-glycosylated, transmembrane protein that is expressed on the apical surface of most secretory epithelia. In malignantly transformed epithelia, MUC1 has lost its apical distribution, is underglycosylated and is secreted into the circulation. Due...... 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...... in vaccination studies as well as for functional assays....

  5. Selection and characterization of a human neutralizing antibody to human fibroblast growth factor-2

    International Nuclear Information System (INIS)

    Tao, Jun; Xiang, Jun-Jian; Li, Dan; Deng, Ning; Wang, Hong; Gong, Yi-Ping

    2010-01-01

    Compelling evidences suggest that fibroblast growth factor-2 (FGF-2) plays important roles in tumor growth, angiogenesis and metastasis. Molecules blocking the FGF-2 signaling have been proposed as anticancer agents. Through screening of a human scFv phage display library, we have isolated several human single-chain Fv fragments (scFvs) that bind to human FGF-2. After expression and purification in bacteria, one scFv, named 1A2, binds to FGF-2 with a high affinity and specificity, and completes with FGF-2 binding to its receptor. This 1A2 scFv was then cloned into the pIgG1 vector and expressed in 293T cells. The purified hIgG1-1A2 antibody showed a high binding affinity of 8 x 10 -9 M to rhFGF-2. In a set of vitro assays, it inhibited various biological activities of FGF-2 such as the proliferation, migration and tube formation of human umbilical vein endothelial cells. More importantly, hIgG1-1A2 antibody also efficiently blocked the growth while inducing apoptosis of glioma cells. For the first time, we generated a human anti-FGF-2 antibody with proven in vitro anti-tumor activity. It may therefore present a new therapeutic candidate for the treatment of cancers that are dependent on FGF-2 signaling for growth and survival.

  6. Evaluation of multiplex assay platforms for detection of influenza hemagglutinin subtype specific antibody responses.

    Science.gov (United States)

    Li, Zhu-Nan; Weber, Kimberly M; Limmer, Rebecca A; Horne, Bobbi J; Stevens, James; Schwerzmann, Joy; Wrammert, Jens; McCausland, Megan; Phipps, Andrew J; Hancock, Kathy; Jernigan, Daniel B; Levine, Min; Katz, Jacqueline M; Miller, Joseph D

    2017-05-01

    Influenza hemagglutination inhibition (HI) and virus microneutralization assays (MN) are widely used for seroprevalence studies. However, these assays have limited field portability and are difficult to fully automate for high throughput laboratory testing. To address these issues, three multiplex influenza subtype-specific antibody detection assays were developed using recombinant hemagglutinin antigens in combination with Chembio, Luminex ® , and ForteBio ® platforms. Assay sensitivity, specificity, and subtype cross-reactivity were evaluated using a panel of well characterized human sera. Compared to the traditional HI, assay sensitivity ranged from 87% to 92% and assay specificity in sera collected from unexposed persons ranged from 65% to 100% across the platforms. High assay specificity (86-100%) for A(H5N1) rHA was achieved for sera from exposed or unexposed to hetorosubtype influenza HAs. In contrast, assay specificity for A(H1N1)pdm09 rHA using sera collected from A/Vietnam/1204/2004 (H5N1) vaccinees in 2008 was low (22-30%) in all platforms. Although cross-reactivity against rHA subtype proteins was observed in each assay platform, the correct subtype specific responses were identified 78%-94% of the time when paired samples were available for analysis. These results show that high throughput and portable multiplex assays that incorporate rHA can be used to identify influenza subtype specific infections. Published by Elsevier B.V.

  7. Tandem bispecific broadly neutralizing antibody - a novel approach to HIV-1 treatment.

    Science.gov (United States)

    Ferrari, Guido

    2018-04-23

    The last decade has led to a significant advance in our knowledge of HIV-1 latency and immunity. However, we are still not close to finding a cure for HIV-1. Although combination antiretroviral therapy (cART) has led to increased survival, almost close to that of the general population, it is still not curative. In the current issue of the JCI, Wu et al. studied the prophylactic and therapeutic potential of an engineered tandem bispecific broadly neutralizing antibody (bs-bnAb), BiIA-SG. This bnAb's breadth and potency were highly effective in protection and treatment settings, as measured by complete viremia control following direct infusion, as well as elimination of infected cells and delay in viral rebound when delivered with a recombinant vector. These observations underscore the need for the clinical development of BiIA-SG for the prevention of HIV-1.

  8. A radiolabeled antiglobulin assay to identify human cervical mucus immunoglobulin (Ig) A and IgG antisperm antibodies

    International Nuclear Information System (INIS)

    Haas, G.G. Jr.; D'Cruz, O.J.

    1989-01-01

    Antisperm immunoglobulin (Ig) A and IgG antibodies in human cervical mucus (CM) were identified by a radiolabeled antiglobulin assay. Cervical mucus samples from fertile and infertile women were exposed to a 1:3,200 dilution of 2-mercaptoethanol (2-ME), and 5 micrograms of the solubilized CM protein were assayed for the presence of IgA and IgG antisperm and anti-Candida activity by the radiolabeled antiglobulin assay. Purified human secretory IgA and IgG exposed to 2-ME retained the molecular integrity and functional activity of the untreated antibody molecules. CM aliquots collected after high-performance liquid chromatography (HPLC) fractionation were assessed for antisperm antibody activity; antisperm antibody activity was retained in the appropriate IgA or IgG CM fractions. The incidence of CM antisperm antibodies was minimally affected when the radiolabeled antiglobulin assay was performed with a motile sperm population. Approximately 70% of the CM IgA antisperm antibodies were of the IgA1 subclass; CM IgG was primarily of the IgG4 subclass. When Candida antigen was substituted for sperm in the radiolabeled antiglobulin assay, the CM antisperm antibodies were found to be exclusively sperm-specific. These data indicate that the radiolabeled antiglobulin assay using 2-ME to extract CM antibodies is a specific method for the assay of antisperm antibodies in CM

  9. Neutralization of antibody-enhanced dengue infection by VIS513, a pan serotype reactive monoclonal antibody targeting domain III of the dengue E protein

    Science.gov (United States)

    Robinson, Luke N.; Ong, Li Ching; Rowley, Kirk J.; Winnett, Alexander; Tan, Hwee Cheng; Hobbie, Sven; Shriver, Zachary; Babcock, Gregory J.; Alonso, Sylvie; Ooi, Eng Eong

    2018-01-01

    Dengue virus (DENV) infection imposes enormous health and economic burden worldwide with no approved treatment. Several small molecules, including lovastatin, celgosivir, balapiravir and chloroquine have been tested for potential anti-dengue activity in clinical trials; none of these have demonstrated a protective effect. Recently, based on identification and characterization of cross-serotype neutralizing antibodies, there is increasing attention on the potential for dengue immunotherapy. Here, we tested the ability of VIS513, an engineered cross-neutralizing humanized antibody targeting the DENV E protein domain III, to overcome antibody-enhanced infection and high but brief viremia, which are commonly encountered in dengue patients, in various in vitro and in vivo models. We observed that VIS513 efficiently neutralizes DENV at clinically relevant viral loads or in the presence of enhancing levels of DENV immune sera. Single therapeutic administration of VIS513 in mouse models of primary infection or lethal secondary antibody-enhanced infection, reduces DENV titers and protects from lethal infection. Finally, VIS513 administration does not readily lead to resistance, either in cell culture systems or in animal models of dengue infection. The findings suggest that rapid viral reduction during acute DENV infection with a monoclonal antibody is feasible. PMID:29425203

  10. Quantitative analyses reveal distinct sensitivities of the capture of HIV-1 primary viruses and pseudoviruses to broadly neutralizing antibodies.

    Science.gov (United States)

    Kim, Jiae; Jobe, Ousman; Peachman, Kristina K; Michael, Nelson L; Robb, Merlin L; Rao, Mangala; Rao, Venigalla B

    2017-08-01

    Development of vaccines capable of eliciting broadly neutralizing antibodies (bNAbs) is a key goal to controlling the global AIDS epidemic. To be effective, bNAbs must block the capture of HIV-1 to prevent viral acquisition and establishment of reservoirs. However, the role of bNAbs, particularly during initial exposure of primary viruses to host cells, has not been fully examined. Using a sensitive, quantitative, and high-throughput qRT-PCR assay, we found that primary viruses were captured by host cells and converted into a trypsin-resistant form in less than five minutes. We discovered, unexpectedly, that bNAbs did not block primary virus capture, although they inhibited the capture of pseudoviruses/IMCs and production of progeny viruses at 48h. Further, viruses escaped bNAb inhibition unless the bNAbs were present in the initial minutes of exposure of virus to host cells. These findings will have important implications for HIV-1 vaccine design and determination of vaccine efficacy. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  11. Antibody induced by immunization with the Jeryl Lynn mumps vaccine strain effectively neutralizes a heterologous wild-type mumps virus associated with a large outbreak.

    Science.gov (United States)

    Rubin, Steven A; Qi, Li; Audet, Susette A; Sullivan, Bradley; Carbone, Kathryn M; Bellini, William J; Rota, Paul A; Sirota, Lev; Beeler, Judy

    2008-08-15

    Recent mumps outbreaks in older vaccinated populations were caused primarily by genotype G viruses, which are phylogenetically distinct from the genotype A vaccine strains used in the countries affected by the outbreaks. This finding suggests that genotype A vaccine strains could have reduced efficacy against heterologous mumps viruses. The remote history of vaccination also suggests that waning immunity could have contributed to susceptibility. To examine these issues, we obtained consecutive serum samples from children at different intervals after vaccination and assayed the ability of these samples to neutralize the genotype A Jeryl Lynn mumps virus vaccine strain and a genotype G wild-type virus obtained during the mumps outbreak that occurred in the United States in 2006. Although the geometric mean neutralizing antibody titers against the genotype G virus were approximately one-half the titers measured against the vaccine strain, and although titers to both viruses decreased with time after vaccination, antibody induced by immunization with the Jeryl Lynn mumps vaccine strain effectively neutralized the outbreak-associated virus at all time points tested.

  12. Optimization of Neutral Comet Assay for studying DNA double-strand breaks in pea and wheat

    Directory of Open Access Journals (Sweden)

    Ivelina Nikolova

    2013-01-01

    Full Text Available This study describes an adaptation of the Comet assay under neutral conditions for mono- and dicotyledonous plants pea (Pisum sativum L. and wheat (Triticum aestivum L.. Modifications concern lysis and electrophoresis steps, respectively. Electrophoresis was carried out varying the intensity of the electric field. A linear relationship between the percentages of DNA in the tail from control background with alteration of intensity was found. Trypan blue dye exclusion test was used in order to determine the intactness of nuclear membrane of the isolated nuclei from both plant model systems. Assessment was conducted on non-irradiated and irradiated nuclei on a monolayer with three doses of UVC. It was found that the share of intact nuclei (trypan blue negative ones is about 95% in controls. Gradual dose-related increase of damaged nuclei was observed in both species, reaching statistical significance only at the higher dose applied.

  13. Mouse in Vivo Neutralization of Escherichia coli Shiga Toxin 2 with Monoclonal Antibodies

    Directory of Open Access Journals (Sweden)

    Larry H. Stanker

    2013-10-01

    Full Text Available Shiga toxin-producing Escherichia coli (STEC food contaminations pose serious health concerns, and have been the subject of massive food recalls. STEC has been identified as the major cause of the life-threatening complication of hemolytic uremic syndrome (HUS. Besides supportive care, there currently are no therapeutics available. The use of antibiotics for combating pathogenic E. coli is not recommended because they have been shown to stimulate toxin production. Clearing Stx2 from the circulation could potentially lessen disease severity. In this study, we tested the in vivo neutralization of Stx2 in mice using monoclonal antibodies (mAbs. We measured the biologic half-life of Stx2 in mice and determined the distribution phase or t1/2 α to be 3 min and the clearance phase or t1/2 β to be 40 min. Neutralizing mAbs were capable of clearing Stx2 completely from intoxicated mouse blood within minutes. We also examined the persistence of these mAbs over time and showed that complete protection could be passively conferred to mice 4 weeks before exposure to Stx2. The advent of better diagnositic methods and the availability of a greater arsenal of therapeutic mAbs against Stx2 would greatly enhance treatment outcomes of life threatening E. coli infections.

  14. Tandem bispecific neutralizing antibody eliminates HIV-1 infection in humanized mice.

    Science.gov (United States)

    Wu, Xilin; Guo, Jia; Niu, Mengyue; An, Minghui; Liu, Li; Wang, Hui; Jin, Xia; Zhang, Qi; Lam, Ka Shing; Wu, Tongjin; Wang, Hua; Wang, Qian; Du, Yanhua; Li, Jingjing; Cheng, Lin; Tang, Hang Ying; Shang, Hong; Zhang, Linqi; Zhou, Paul; Chen, Zhiwei

    2018-04-23

    The discovery of an HIV-1 cure remains a medical challenge because the virus rebounds quickly after the cessation of combination antiretroviral therapy (cART). Here, we investigate the potential of an engineered tandem bispecific broadly neutralizing antibody (bs-bnAb) as an innovative product for HIV-1 prophylactic and therapeutic interventions. We discovered that by preserving 2 single-chain variable fragment (scFv) binding domains of each parental bnAb, a single gene-encoded tandem bs-bnAb, BiIA-SG, displayed substantially improved breadth and potency. BiIA-SG neutralized all 124 HIV-1-pseudotyped viruses tested, including global subtypes/recombinant forms, transmitted/founder viruses, variants not susceptible to parental bnAbs and to many other bnAbs with an average IC50 value of 0.073 μg/ml (range HIV-1 stains. Moreover, whereas BiIA-SG delayed viral rebound in a short-term therapeutic setting when combined with cART, a single injection of adeno-associated virus-transferred (AAV-transferred) BiIA-SG gene resulted dose-dependently in prolonged in vivo expression of BiIA-SG, which was associated with complete viremia control and subsequent elimination of infected cells in humanized mice. These results warrant the clinical development of BiIA-SG as a promising bs-bnAb-based biomedical intervention for the prevention and treatment of HIV-1 infection.

  15. Broadly neutralizing antibodies for treatment and prevention of HIV-1 infection.

    Science.gov (United States)

    Cohen, Yehuda Z; Caskey, Marina

    2018-04-24

    Several anti-HIV-1 broadly neutralizing antibodies (bNAbs) with exceptional breadth and potency that target different HIV-1 envelope epitopes have been identified. bNAbs are an attractive new strategy for HIV-1 prevention and therapy, and potentially, for long-term remission or cure. Here, we discuss findings from early clinical studies that have evaluated these novel bNAbs. Phase 1 studies of bNAbs targeting two distinct HIV-1 envelope epitopes have demonstrated their favorable safety and pharmacokinetic profile. Single bNAb infusions led to significant, but transient, decline in viremia with selection of escape variants. A single bNAb also delayed viral rebound in ART-treated participants who discontinued ART. Importantly, in-vivo efficacy was related to antibody potency and to the level of preexisting resistance. Studies in animal models showed that bNAbs can clear HIV-infected cells and modulate host immune responses. These findings suggest that bNAbs may target the latent HIV reservoir in humans and could contribute to long-term remission of HIV-1 infection. bNAbs may offer advantages over traditional ART for both the prevention and treatment of HIV-1 infection. In addition, bNAbs may target the latent viral reservoir. bNAb combinations and bNAbs engineered for prolonged half-life and increased potency are currently undergoing clinical evaluation.

  16. High-sensitivity immunochromatographic assay for fumonisin B1 based on indirect antibody labeling.

    Science.gov (United States)

    Urusov, Alexandr E; Petrakova, Alina V; Gubaydullina, Milyausha K; Zherdev, Anatoly V; Eremin, Sergei A; Kong, Dezhao; Liu, Liqiang; Xu, Chuanlai; Dzantiev, Boris B

    2017-05-01

    To develop a high-sensitivity immunochromatographic test for fumonisin B1 in plant extracts. Unlike conventional immunochromatographic tests, this assay is performed in two stages: competitive reaction with free specific antibodies and identifying immune complexes by their interaction with the anti-species antibody-conjugated gold nanoparticles. The use of a new geometry for the test strip membranes and a novel reagent application method ensures the proper order of these stages without additional manipulations. The contact of the ready-to-use test strip with the liquid sample suffices in initiating all stages of the assay and obtaining test results. The developed test was used on corn extracts; its instrumental limit of fumonisin B1 detection was 0.6 ng ml -1 at 15 min of assay duration. The proposed approach is flexible and can be used for a wide range of low molecular compounds. The use of anti-species antibody-conjugated gold nanoparticles in immunochromatography significantly facilitates the development of test systems by eliminating the need to synthesize and characterize the conjugates with specific antibodies for each new compound to be detected.

  17. Detection of antibodies to the extractable nuclear antigens by enzyme linked immunosorbent assay

    International Nuclear Information System (INIS)

    Aziz, Khalil A.; Fzizal, Abul A.

    2005-01-01

    Anti-extractable nuclear antigen (ENA) antibodies are a group of autoantibodies that are directed against various components of the cell nucleus. Antibodies to these antigens are closely associated with connective tissue disease. Early diagnosis of these diseases can prove very difficult and therefore clinicians rely on the use of anti-ENA antibody testing for the exclusion. Old methods of testing are time consuming and require great skills. For these reasons clinical immunology laboratories are switching to testing for anti-ENA antibodies by enzyme linked immunosorbent assay (ELISA). The latter assays are more sensitive and require little skills. In the present study we have investigated a number of different ELISA preparations. The study was conducted at Birmingham Heartlands Hospital during the period 2003. We tested a number of ENA-positive and negative samples using 3 different commercial ELISA preparations and compared the results with traditional CCIE-assay. The present study revealed that some ELISA preparations can be more sensitive than CCIE method. Laboratories still using later method should switch to ELISA. However it is important that laboratories evaluate a long range of different ELISA preparations before selecting the most optimal one. In addition it is recommended that laboratories then audit results in order to determine true significance of such results. Finally until the true significance of ELISA generated results is known, positive ENA-results should be interpreted in conjunction with the clinical picture and this would require close liaison in between the clinical immunology laboratory and clinicians

  18. In Vivo Neutralization of α-Cobratoxin with High-Affinity Llama Single-Domain Antibodies (VHHs) and a VHH-Fc Antibody

    Science.gov (United States)

    Richard, Gabrielle; Meyers, Ashley J.; McLean, Michael D.; Arbabi-Ghahroudi, Mehdi; MacKenzie, Roger; Hall, J. Christopher

    2013-01-01

    Small recombinant antibody fragments (e.g. scFvs and VHHs), which are highly tissue permeable, are being investigated for antivenom production as conventional antivenoms consisting of IgG or F(ab’)2 antibody fragments do not effectively neutralize venom toxins located in deep tissues. However, antivenoms composed entirely of small antibody fragments may have poor therapeutic efficacy due to their short serum half-lives. To increase serum persistence and maintain tissue penetration, we prepared low and high molecular mass antivenom antibodies. Four llama VHHs were isolated from an immune VHH-displayed phage library and were shown to have high affinity, in the low nM range, for α-cobratoxin (α–Cbtx), the most lethal component of Naja kaouthia venom. Subsequently, our highest affinity VHH (C2) was fused to a human Fc fragment to create a VHH2-Fc antibody that would offer prolonged serum persistence. After in planta (Nicotiana benthamiana) expression and purification, we show that our VHH2-Fc antibody retained high affinity binding to α–Cbtx. Mouse α–Cbtx challenge studies showed that our highest affinity VHHs (C2 and C20) and the VHH2-Fc antibody effectively neutralized lethality induced by α–Cbtx at an antibody:toxin molar ratio as low as ca. 0.75×:1. Further research towards the development of an antivenom therapeutic involving these anti-α-Cbtx VHHs and VHH2-Fc antibody molecules should involve testing them as a combination, to determine whether they maintain tissue penetration capability and low immunogenicity, and whether they exhibit improved serum persistence and therapeutic efficacy. PMID:23894495

  19. A surface plasmon resonance assay for characterisation and epitope mapping of anti-GLP-1 antibodies.

    Science.gov (United States)

    Thomsen, Lasse; Gurevich, Leonid

    2018-04-19

    The incretin hormone glucagon-like peptide-1 (GLP-1) has been subject to substantial pharmaceutical research regarding the treatment of type 2 diabetes mellitus. However, quantification of GLP-1 levels remains complicated due to the low circulation concentration and concurrent existence of numerous metabolites, homologous peptides, and potentially introduced GLP-1 receptor agonists. Surface plasmon resonance (SPR) facilitates real-time monitoring allowing a more detailed characterisation of the interaction compared with conventional enzyme-linked immunosorbent assays (ELISA). In this paper, we describe the development of the first SPR assays for characterisation of anti-GLP-1 antibodies for ELISA purposes. Binding responses were obtained on covalently immobilised anti-GLP-1 antibodies at 12°C, 25°C, and 40°C and fitted to a biomolecular (1:1) interaction model showing association rates of 1.01 × 10 3 to 4.54 × 10 3  M -1  s -1 and dissociation rates of 3.56 × 10 -5 to 1.56 × 10 -3  s -1 leading to affinities of 35.2 to 344 nM, depending on the temperature. Determination of thermodynamic properties revealed an enthalpy driven interaction (ΔH polar amino acids (ΔC p  < 0). Pair-wise epitope mapping was performed on captured anti-GLP-1 antibodies followed by subsequent interaction with GLP-1 (7-36) and other anti-GLP-1 antibodies. A global evaluation of every binding response led to an epitope map elucidating the potential of various anti-GLP-1 antibody pairs for sandwich ELISA and hence pinpointing the optimal antibody combinations. The SPR assays proved capable of providing vital information for ELISA development endorsing it as a useful optimisation tool. Copyright © 2018 John Wiley & Sons, Ltd.

  20. Epitope mapping and characterization of a novel CD4-induced human monoclonal antibody capable of neutralizing primary HIV-1 strains

    International Nuclear Information System (INIS)

    Xiang Shihua; Wang Liping; Abreu, Mariam; Huang, C.-C.; Kwong, Peter D.; Rosenberg, Eric; Robinson, James E.; Sodroski, Joseph

    2003-01-01

    Human immunodeficiency virus (HIV-1) enters target cells by binding its gp120 exterior envelope glycoprotein to CD4 and one of the chemokine receptors, CCR5 or CXCR4. CD4-induced (CD4i) antibodies bind gp120 more efficiently after CD4 binding and block the interaction with the chemokine receptor. Examples of CD4i antibodies are limited, and the prototypes of the CD4i antibodies exhibit only weak neutralizing activity against primary, clinical HIV-1 isolates. Here we report the identification of a novel antibody, E51, that exhibits CD4-induced binding to gp120 and neutralizes primary HIV-1 more efficiently than the prototypic CD4i antibodies. The E51 antibody blocks the interaction of gp120-CD4 complexes with CCR5 and binds to a highly conserved, basic gp120 element composed of the β19-strand and surrounding structures. Thus, on primary HIV-1 isolates, this gp120 region, which has been previously implicated in chemokine receptor binding, is accessible to a subset of CD4i antibodies

  1. Universal antibodies against the highly conserved influenza fusion peptide cross-neutralize several subtypes of influenza A virus

    Energy Technology Data Exchange (ETDEWEB)

    Hashem, Anwar M. [Centre for Vaccine Evaluation, Biologics and Genetic Therapies Directorate, HPFB, Health Canada, Ottawa, ON (Canada); Department of Microbiology, Faculty of Medicine, King Abdulaziz University, Jeddah (Saudi Arabia); Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON (Canada); Van Domselaar, Gary [National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB (Canada); Li, Changgui; Wang, Junzhi [National Institute for the Control of Pharmaceutical and Biological Products, Beijing (China); She, Yi-Min; Cyr, Terry D. [Centre for Vaccine Evaluation, Biologics and Genetic Therapies Directorate, HPFB, Health Canada, Ottawa, ON (Canada); Sui, Jianhua [Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Medicine, Harvard Medical School, 44 Binney Street, Boston, MA 02115 (United States); He, Runtao [National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, MB (Canada); Marasco, Wayne A. [Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Department of Medicine, Harvard Medical School, 44 Binney Street, Boston, MA 02115 (United States); Li, Xuguang, E-mail: Sean.Li@hc-sc.gc.ca [Centre for Vaccine Evaluation, Biologics and Genetic Therapies Directorate, HPFB, Health Canada, Ottawa, ON (Canada); Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON (Canada)

    2010-12-10

    Research highlights: {yields} The fusion peptide is the only universally conserved epitope in all influenza viral hemagglutinins. {yields} Anti-fusion peptide antibodies are universal antibodies that cross-react with all influenza HA subtypes. {yields} The universal antibodies cross-neutralize different influenza A subtypes. {yields} The universal antibodies inhibit the fusion process between the viruses and the target cells. -- Abstract: The fusion peptide of influenza viral hemagglutinin plays a critical role in virus entry by facilitating membrane fusion between the virus and target cells. As the fusion peptide is the only universally conserved epitope in all influenza A and B viruses, it could be an attractive target for vaccine-induced immune responses. We previously reported that antibodies targeting the first 14 amino acids of the N-terminus of the fusion peptide could bind to virtually all influenza virus strains and quantify hemagglutinins in vaccines produced in embryonated eggs. Here we demonstrate that these universal antibodies bind to the viral hemagglutinins in native conformation presented in infected mammalian cell cultures and neutralize multiple subtypes of virus by inhibiting the pH-dependant fusion of viral and cellular membranes. These results suggest that this unique, highly-conserved linear sequence in viral hemagglutinin is exposed sufficiently to be attacked by the antibodies during the course of infection and merits further investigation because of potential importance in the protection against diverse strains of influenza viruses.

  2. Universal antibodies against the highly conserved influenza fusion peptide cross-neutralize several subtypes of influenza A virus

    International Nuclear Information System (INIS)

    Hashem, Anwar M.; Van Domselaar, Gary; Li, Changgui; Wang, Junzhi; She, Yi-Min; Cyr, Terry D.; Sui, Jianhua; He, Runtao; Marasco, Wayne A.; Li, Xuguang

    2010-01-01

    Research highlights: → The fusion peptide is the only universally conserved epitope in all influenza viral hemagglutinins. → Anti-fusion peptide antibodies are universal antibodies that cross-react with all influenza HA subtypes. → The universal antibodies cross-neutralize different influenza A subtypes. → The universal antibodies inhibit the fusion process between the viruses and the target cells. -- Abstract: The fusion peptide of influenza viral hemagglutinin plays a critical role in virus entry by facilitating membrane fusion between the virus and target cells. As the fusion peptide is the only universally conserved epitope in all influenza A and B viruses, it could be an attractive target for vaccine-induced immune responses. We previously reported that antibodies targeting the first 14 amino acids of the N-terminus of the fusion peptide could bind to virtually all influenza virus strains and quantify hemagglutinins in vaccines produced in embryonated eggs. Here we demonstrate that these universal antibodies bind to the viral hemagglutinins in native conformation presented in infected mammalian cell cultures and neutralize multiple subtypes of virus by inhibiting the pH-dependant fusion of viral and cellular membranes. These results suggest that this unique, highly-conserved linear sequence in viral hemagglutinin is exposed sufficiently to be attacked by the antibodies during the course of infection and merits further investigation because of potential importance in the protection against diverse strains of influenza viruses.

  3. Monoclonal antibodies to human factor VII: a one step immunoradiometric assay for VII:Ag.

    OpenAIRE

    Takase, T; Tuddenham, E G; Chand, S; Goodall, A H

    1988-01-01

    Three mouse monoclonal antibodies (RFF-VII/1, RFF-VII/2, and RFF-VII/3) which bind specifically to different epitopes on human factor VII antigen were raised. Two of the antibodies, RFF-VII/1 and RFF-VII/2, bound strongly to factor VII antigen (VII:Ag), but only RFF-VII/1 and RFF-VII/3 were potent inhibitors of factor VII coagulation activity (VII:C). RFF-VII/1 and RFF-VII/2 were used in a one step, double monoclonal immunoradiometric assay for VII:Ag. This was highly reproducible and detecte...

  4. A biotin-drug extraction and acid dissociation (BEAD) procedure to eliminate matrix and drug interference in a protein complex anti-drug antibody (ADA) isotype specific assay.

    Science.gov (United States)

    Niu, Hongmei; Klem, Thomas; Yang, Jinsong; Qiu, Yongchang; Pan, Luying

    2017-07-01

    Monitoring anti-drug antibody (ADA) responses in patients receiving protein therapeutics treatment is an important safety assessment for regulatory agencies, drug manufacturers, clinicians and patients. Recombinant human IGF-1/IGFBP-3 (rhIGF-1/rhIGFBP-3) is a 1:1 formulation of naturally occurring protein complex. The individual IGF-1 and IGFBP-3 proteins have multiple binding partners in serum matrix with high binding affinity to each other, which presents challenges in ADA assay development. We have developed a biotin-drug extraction with acid dissociation (BEAD) procedure followed by an electrochemiluminescence (ECL) direct assay to overcome matrix and drug interference. The method utilizes two step acid dissociation and excess biotin-drug to extract total ADA, which are further captured by soluble biotin-drug and detected in an ECL semi-homogeneous direct assay format. The pre-treatment method effectively eliminates interference by serum matrix and free drug, and enhances assay sensitivity. The assays passed acceptance criteria for all validation parameters, and have been used for clinical sample Ab testing. This method principle exemplifies a new approach for anti-isotype ADA assays, and could be an effective strategy for neutralizing antibody (NAb), pharmacokinetic (PK) and biomarker analysis in need of overcoming interference factors. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Molecular aspects of antibody-antigen interactions : size reduction of a herpes simplex virus neutralizing antibody and its antigen

    NARCIS (Netherlands)

    Schellekens, Gerardus Antonius

    1996-01-01

    Antibody molecules, produced as a response against foreign substances, interact with their antigen in a very specific manner. Antibodies with a predetermined specificity (monoclonal antibodies) can be produced and are widely used in medicine and science as indicator molecules. Genetic engineering of

  6. Induction and characterization of monoclonal anti-idiotypic antibodies reactive with idiotopes of canine parvovirus neutralizing monoclonal antibodies.

    NARCIS (Netherlands)

    G.F. Rimmelzwaan (Guus); J. van Es (Johan); G.A. Drost; F.G.C.M. Uytdehaag (Fons); A.D.M.E. Osterhaus (Albert)

    1991-01-01

    textabstractMonoclonal anti-idiotypic (anti-Id) antibodies (Ab2) were generated against idiotypes (Id) of canine parvovirus (CPV) specific monoclonal antibodies (MoAbs). The binding of most of these anti-Id antibodies to their corresponding Id could be inhibited by antigen, thus classifying these

  7. Detection of extensive cross-neutralization between pandemic and seasonal A/H1N1 Influenza Viruses using a pseudotype neutralization assay.

    Directory of Open Access Journals (Sweden)

    Béatrice Labrosse

    Full Text Available BACKGROUND: Cross-immunity between seasonal and pandemic A/H1N1 influenza viruses remains uncertain. In particular, the extent that previous infection or vaccination by seasonal A/H1N1 viruses can elicit protective immunity against pandemic A/H1N1 is unclear. METHODOLOGY/PRINCIPAL FINDINGS: Neutralizing titers against seasonal A/H1N1 (A/Brisbane/59/2007 and against pandemic A/H1N1 (A/California/04/2009 were measured using an HIV-1-based pseudovirus neutralization assay. Using this highly sensitive assay, we found that a large fraction of subjects who had never been exposed to pandemic A/H1N1 express high levels of pandemic A/H1N1 neutralizing titers. A significant correlation was seen between neutralization of pandemic A/H1N1 and neutralization of a standard seasonal A/H1N1 strain. Significantly higher pandemic A/H1N1 neutralizing titers were measured in subjects who had received vaccination against seasonal influenza in 2008-2009. Higher pandemic neutralizing titers were also measured in subjects over 60 years of age. CONCLUSIONS/SIGNIFICANCE: Our findings reveal that the extent of protective cross-immunity between seasonal and pandemic A/H1N1 influenza viruses may be more important than previously estimated. This cross-immunity could provide a possible explanation of the relatively mild profile of the recent influenza pandemic.

  8. Antibody response to a synthetic peptide covering a LAV-1/HTLV-IIIB neutralization epitope and disease progression

    NARCIS (Netherlands)

    Boucher, C. A.; de Wolf, F.; Houweling, J. T.; Bakker, M.; Dekker, J.; Roos, M. T.; Coutinho, R. A.; van der Noordaa, J.; Goudsmit, J.

    1989-01-01

    Sequential sera of homosexual men participating in a prospective study on the incidence of HIV-1 infection and risk factors for AIDS were tested for the presence of antibodies to a synthetic 17-mer (Neu21; KSIRIQRGPGRAFVTIG) representing a neutralization epitope as present on the LAV-1/HTLV-IIIB

  9. In vivo evaluation of the cross-genotype neutralizing activity of polyclonal antibodies against hepatitis C virus

    DEFF Research Database (Denmark)

    Meuleman, Philip; Bukh, Jens; Verhoye, Lieven

    2011-01-01

    Control of hepatitis C virus (HCV) infection remains a huge challenge of global medical importance. Using a variety of in vitro approaches, neutralizing antibodies (nAbs) have been identified in patients with acute and chronic hepatitis C. The exact role these nAbs play in the resolution of acute...

  10. Isolation and characterization of broadly neutralizing human monoclonal antibodies to the e1 glycoprotein of hepatitis C virus

    DEFF Research Database (Denmark)

    Meunier, Jean-Christophe; Russell, Rodney S; Goossens, Vera

    2008-01-01

    monoclonal antibodies (MAbs) directed against HCV glycoprotein E1, which may have the potential to control HCV infection. We have identified two MAbs that can strongly neutralize HCV-pseudotyped particles (HCVpp) bearing the envelope glycoproteins of genotypes 1a, 1b, 4a, 5a, and 6a and less strongly...

  11. ELISA to measure neutralizing capacity of anti-C1-inhibitor antibodies in plasma of angioedema patients

    NARCIS (Netherlands)

    Engel, Ruchira; Rensink, Irma; Roem, Dorina; Brouwer, Mieke; Kalei, Asma; Perry, Dawn; Zeerleder, Sacha; Wouters, Diana; Hamann, Dörte

    2015-01-01

    Neutralizing autoantibodies (NAbs) against plasma serpin C1-inhibitor (C1-inh) are implicated in the rare disorder, acquired angioedema (AAE). There is insufficient understanding of the process of antibody formation and its correlation with disease progression and severity. We have developed an

  12. Cross-Neutralizing Antibodies in HIV-1 Individuals Infected by Subtypes B, F1, C or the B/Bbr Variant in Relation to the Genetics and Biochemical Characteristics of the env Gene.

    Directory of Open Access Journals (Sweden)

    Dalziza Victalina de Almeida

    Full Text Available Various HIV-1 env genetic and biochemical features impact the elicitation of cross-reactive neutralizing antibodies in natural infections. Thus, we aimed to investigate cross-neutralizing antibodies in individuals infected with HIV-1 env subtypes B, F1, C or the B/Bbr variant as well as env characteristics. Therefore, plasma samples from Brazilian chronically HIV-1 infected individuals were submitted to the TZM-bl neutralization assay. We also analyzed putative N-glycosylation sites (PNGLs and the size of gp120 variable domains in the context of HIV-1 subtypes prevalent in Brazil. We observed a greater breadth and potency of the anti-Env neutralizing response in individuals infected with the F1 or B HIV-1 subtypes compared with the C subtype and the variant B/Bbr. We observed greater V1 B/Bbr and smaller V4 F1 than those of other subtypes (p<0.005, however neither was there a correlation verified between the variable region length and neutralization potency, nor between PNLG and HIV-1 subtypes. The enrichment of W at top of V3 loop in weak neutralizing response viruses and the P in viruses with higher neutralization susceptibility was statistically significant (p = 0.013. Some other signatures sites were associated to HIV-1 subtype-specific F1 and B/Bbr samples might influence in the distinct neutralizing response. These results indicate that a single amino acid substitution may lead to a distinct conformational exposure or load in the association domain of the trimer of gp120 and interfere with the induction power of the neutralizing response, which affects the sensitivity of the neutralizing antibody and has significant implications for vaccine design.

  13. Virus-neutralizing antibody response of mice to consecutive infection with human and avian influenza A viruses.

    Science.gov (United States)

    Janulíková, J; Stropkovská, A; Bobišová, Z; Košík, I; Mucha, V; Kostolanský, F; Varečková, E

    2015-06-01

    In this work we simulated in a mouse model a naturally occurring situation of humans, who overcame an infection with epidemic strains of influenza A, and were subsequently exposed to avian influenza A viruses (IAV). The antibody response to avian IAV in mice previously infected with human IAV was analyzed. We used two avian IAV (A/Duck/Czechoslovakia/1956 (H4N6) and the attenuated virus rA/Viet Nam/1203-2004 (H5N1)) as well as two human IAV isolates (virus A/Mississippi/1/1985 (H3N2) of medium virulence and A/Puerto Rico/8/1934 (H1N1) of high virulence). Two repeated doses of IAV of H4 or of H5 virus elicited virus-specific neutralizing antibodies in mice. Exposure of animals previously infected with human IAV (of H3 or H1 subtype) to IAV of H4 subtype led to the production of antibodies neutralizing H4 virus in a level comparable with the level of antibodies against the human IAV used for primary infection. In contrast, no measurable levels of virus-neutralizing (VN) antibodies specific to H5 virus were detected in mice infected with H5 virus following a previous infection with human IAV. In both cases the secondary infection with avian IAV led to a significant increase of the titer of VN antibodies specific to the corresponding human virus used for primary infection. Moreover, cross-reactive HA2-specific antibodies were also induced by sequential infection. By virtue of these results we suggest that the differences in the ability of avian IAV to induce specific antibodies inhibiting virus replication after previous infection of mice with human viruses can have an impact on the interspecies transmission and spread of avian IAV in the human population.

  14. In vivo neutralization of hepatitis B virus infection by an anti-preS1 humanized antibody in chimpanzees

    International Nuclear Information System (INIS)

    Hong, Hyo Jeong; Ryu, Chun Jeih; Hur, Hyangsuk; Kim, Seho; Oh, Han Kyu; Oh, Mee Sook; Park, Song Yong

    2004-01-01

    Previously, we generated a murine monoclonal antibody (mAb), KR127, that recognizes amino acids (aa) 37-45 of the preS1 of hepatitis B virus (HBV). In this study, we have constructed a humanized version of KR127 and evaluated its HBV-neutralizing activity in chimpanzees. A study chimpanzee was given a single intravenous dose of the humanized antibody, followed by intravenous challenge with adr subtype of wild type HBV, while a control chimpanzee was only challenged with the virus. The result showed that the study chimpanzee did not develop HBV infection during 1 year, while the control chimpanzee was infected, indicating that the humanized antibody exhibited in vivo virus-neutralizing activity and thus protected the chimpanzee from HBV infection. In addition, the humanized antibody bound to the preS1 of all subtypes of HBV. We first demonstrate that an anti-preS1 mAb can neutralize HBV infection in vivo. This humanized antibody will be useful for the immunoprophylaxis of HBV infection

  15. Cooperativity between CD8+ T cells, non-neutralizing antibodies, and alveolar macrophages is important for heterosubtypic influenza virus immunity.

    Directory of Open Access Journals (Sweden)

    Brian J Laidlaw

    2013-03-01

    Full Text Available Seasonal epidemics of influenza virus result in ∼36,000 deaths annually in the United States. Current vaccines against influenza virus elicit an antibody response specific for the envelope glycoproteins. However, high mutation rates result in the emergence of new viral serotypes, which elude neutralization by preexisting antibodies. T lymphocytes have been reported to be capable of mediating heterosubtypic protection through recognition of internal, more conserved, influenza virus proteins. Here, we demonstrate using a recombinant influenza virus expressing the LCMV GP33-41 epitope that influenza virus-specific CD8+ T cells and virus-specific non-neutralizing antibodies each are relatively ineffective at conferring heterosubtypic protective immunity alone. However, when combined virus-specific CD8 T cells and non-neutralizing antibodies cooperatively elicit robust protective immunity. This synergistic improvement in protective immunity is dependent, at least in part, on alveolar macrophages and/or other lung phagocytes. Overall, our studies suggest that an influenza vaccine capable of eliciting both CD8+ T cells and antibodies specific for highly conserved influenza proteins may be able to provide heterosubtypic protection in humans, and act as the basis for a potential "universal" vaccine.

  16. 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.

  17. The breadth and titer of maternal HIV-1-specific heterologous neutralizing antibodies are not associated with a lower rate of mother-to-child transmission of HIV-1.

    Science.gov (United States)

    Chaillon, Antoine; Wack, Thierry; Braibant, Martine; Mandelbrot, Laurent; Blanche, Stéphane; Warszawski, Josiane; Barin, Francis

    2012-10-01

    It has been hypothesized that neutralizing antibodies (NAbs) should have broad specificity to be effective in protection against diverse HIV-1 variants. The mother-to-child transmission model of HIV-1 provides the opportunity to examine whether the breadth of maternal NAbs is associated with protection of infants from infection. Samples were obtained at delivery from 57 transmitting mothers (T) matched with 57 nontransmitting mothers (NT) enrolled in the multicenter French perinatal cohort (ANRS EPF CO1) between 1990 and 1996. Sixty-eight (59.6%) and 46 (40.4%) women were infected by B and non-B viruses, respectively. Neutralization assays were carried out with TZM-bl cells, using a panel of 10 primary isolates of 6 clades (A, B, C, F, CRF01_AE, and CRF02_AG), selected for their moderate or low sensitivity to neutralization. Neutralization breadths were not statistically different between T and NT mothers. However, a few statistically significant differences were observed, with higher frequencies or titers of NAbs toward several individual strains for NT mothers when the clade B-infected or non-clade B-infected mothers were analyzed separately. Our study confirms that the breadth of maternal NAbs is not associated with protection of infants from infection.

  18. Identification of a CD4-Binding-Site Antibody to HIV that Evolved Near-Pan Neutralization Breadth

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jinghe; Kang, Byong H.; Ishida, Elise; Zhou, Tongqing; Griesman, Trevor; Sheng, Zizhang; Wu, Fan; Doria-Rose, Nicole A.; Zhang, Baoshan; McKee, Krisha; O’Dell, Sijy; Chuang, Gwo-Yu; Druz, Aliaksandr; Georgiev, Ivelin S.; Schramm, Chaim A.; Zheng, Anqi; Joyce, M.  Gordon; Asokan, Mangaiarkarasi; Ransier, Amy; Darko, Sam; Migueles, Stephen A.; Bailer, Robert T.; Louder, Mark K.; Alam, S.  Munir; Parks, Robert; Kelsoe, Garnett; Von Holle, Tarra; Haynes, Barton F.; Douek, Daniel C.; Hirsch, Vanessa; Seaman, Michael S.; Shapiro, Lawrence; Mascola, John R.; Kwong, Peter D.; Connors, Mark

    2016-11-01

    Detailed studies of the broadly neutralizing antibodies (bNAbs) that underlie the best available examples of the humoral immune response to HIV are providing important information for the development of therapies and prophylaxis for HIV-1 infection. Here, we report a CD4-binding site (CD4bs) antibody, named N6, that potently neutralized 98% of HIV-1 isolates, including 16 of 20 that were resistant to other members of its class. N6 evolved a mode of recognition such that its binding was not impacted by the loss of individual contacts across the immunoglobulin heavy chain. In addition, structural analysis revealed that the orientation of N6 permitted it to avoid steric clashes with glycans, which is a common mechanism of resistance. Thus, an HIV-1-specific bNAb can achieve potent, near-pan neutralization of HIV-1, making it an attractive candidate for use in therapy and prophylaxis.

  19. Potent neutralization of influenza A virus by a single-domain antibody blocking M2 ion channel protein.

    Directory of Open Access Journals (Sweden)

    Guowei Wei

    Full Text Available Influenza A virus poses serious health threat to humans. Neutralizing antibodies against the highly conserved M2 ion channel is thought to offer broad protection against influenza A viruses. Here, we screened synthetic Camel single-domain antibody (VHH libraries against native M2 ion channel protein. One of the isolated VHHs, M2-7A, specifically bound to M2-expressed cell membrane as well as influenza A virion, inhibited replication of both amantadine-sensitive and resistant influenza A viruses in vitro, and protected mice from a lethal influenza virus challenge. Moreover, M2-7A showed blocking activity for proton influx through M2 ion channel. These pieces of evidence collectively demonstrate for the first time that a neutralizing antibody against M2 with broad specificity is achievable, and M2-7A may have potential for cross protection against a number of variants and subtypes of influenza A viruses.

  20. Human antibodies that neutralize primary human immunodeficiency virus type 1 in vitro do not provide protection in an in vivo model.

    NARCIS (Netherlands)

    M. Schutten (Martin); K. Tenner-Racz; P. Racz; D.W. van Bekkum (Dirk); A.D.M.E. Osterhaus (Albert)

    1996-01-01

    textabstractRecently, conflicting data have been published about the ability of antibodies which efficiently neutralize T cell-adapted human immunodeficiency virus type 1 (HIV-1) strains to neutralize primary HIV-1 strains in vitro and in vivo. Here we present data indicating that such antibodies

  1. Influenza virus neutralizing antibodies and IgG isotype profiles after immunization of mice with influenza A subunit vaccine using various adjuvants

    NARCIS (Netherlands)

    Benne, CA; Harmsen, M; vanderGraaff, W; Verheul, AFM; Snippe, H; Kraaijeveld, CA

    The influence of various adjuvants on the development of influenza virus neutralizing antibodies and distribution of anti-influenza virus IgG isotypes after immunization of mice with influenza A (H3N2) subunit vaccine was investigated. Serum titres of influenza virus neutralizing antibodies and

  2. Neutralizing antibodies induced by recombinant virus-like particles of enterovirus 71 genotype C4 inhibit infection at pre- and post-attachment steps.

    Directory of Open Access Journals (Sweden)

    Zhiqiang Ku

    Full Text Available BACKGROUND: Enterovirus 71 (EV71 is a major causative agent of hand, foot and mouth disease, which has been prevalent in Asia-Pacific regions, causing significant morbidity and mortality in young children. Antibodies elicited by experimental EV71 vaccines could neutralize infection in vitro and passively protect animal models from lethal challenge, indicating that neutralizing antibodies play an essential role in protection. However, how neutralizing antibodies inhibit infection in vitro remains unclear. METHODS/FINDINGS: In the present study, we explored the mechanisms of neutralization by antibodies against EV71 virus-like particles (VLPs. Recombinant VLPs of EV71 genotype C4 were produced in insect cells using baculovirus vectors. Immunization with the VLPs elicited a high-titer, EV71-specific antibody response in mice. Anti-VLP mouse sera potently neutralized EV71 infection in vitro. The neutralizing antibodies in the anti-VLP mouse sera were found to target mainly an extremely conserved epitope (FGEHKQEKDLEYGAC located at the GH loop of the VP1 protein. The neutralizing anti-VLP antisera were able to inhibit virus binding to target cells efficiently. In addition, post-attachment treatment of virus-bound cells with the anti-VLP antisera also neutralized virus infection, although the antibody concentration required was higher than that of the pre-attachment treatment. CONCLUSIONS: Collectively, our findings represent a valuable addition to the understanding of mechanisms of EV71 neutralization and have strong implications for EV71 vaccine development.

  3. Monoclonal antibodies to human factor VII: production of immunodepleted plasma for VII:C assays.

    OpenAIRE

    Takase, T; Tuddenham, E G; Chand, S; Goodall, A H

    1988-01-01

    A high affinity monoclonal antibody to factor VII (RFF-VII/1), coupled to sepharose, was used to immunodeplete factor VII from normal plasma. The plasma could be used as a substrate in a one stage coagulation assay and performed as well as, or better than, commercially available factor VII deficient plasma or plasma from congenitally deficient factor VII patients. Plasma from normal donors (n = 20), patients with liver disease (n = 20), and patients receiving warfarin (n = 20), or congenitall...

  4. Rapid enzyme-linked immunosorbent assay (ELISA) for Aspergillus fumigatus antibodies.

    OpenAIRE

    Richardson, M D; Stubbins, J M; Warnock, D W

    1982-01-01

    A rapid enzyme-linked immunosorbent assay (ELISA) where component incubation periods were shortened to one hour, was compared with agar gel double diffusion (AGDD) and a standard ELISA procedure for detecting antibodies to Aspergillus fumigatus in 28 asthmatic patients with suspected allergic aspergillosis. Using two A fumigatus antigens the rapid ELISA compared well with AGDD and the standard ELISA method. Eleven sera that reacted with both antigens in AGDD were all positive against antigen ...

  5. Detection of thyroid stimulating hormone receptor antibodies (TRAb) by radioreceptor assay (RRA) and enzyme-linked immunosorbent assay (ELISA)

    International Nuclear Information System (INIS)

    Dumrongpisutikul, S.; Tuchinda, S.

    1990-01-01

    Thyroid stimulating hormone receptor antibodies (TRAb) were determined in 100 patients using radioreceptor assay (RRA) and enzyme-linked immunosorbent assay (ELISA). The sensitivity of RRA and ELISA were found to be 70.6% and 88.2% respectively (n=51). The specificity of both assays were 100% (n=16). With RRA as the standard test the sensitivity and specificity of ELISA were 75.8% and 86.8%. In the untreated hyperthyroid the RRA result which expressed as % specific 125 I-TSH inhibition was 33.6% (n=51), decline to 26.9% in the treated hyperthyroid (n=33) and 14.1% in the euthyroid (n=16). The mean 0.D 492nm of TRAb-ELISA were 0.861 in untreated hyperthyroid, 0.437 in treated hyperthyroid and 0.135 in euthyroid Phi coefficient analysis show that the RRA was 60.4% correlated to hyperthyroidism where as TRAb-ELISA was 80.1%

  6. Cross-neutralization of antibodies induced by vaccination with Purified Chick Embryo Cell Vaccine (PCECV) against different Lyssavirus species.

    Science.gov (United States)

    Malerczyk, Claudius; Freuling, Conrad; Gniel, Dieter; Giesen, Alexandra; Selhorst, Thomas; Müller, Thomas

    2014-01-01

    Rabies is a neglected zoonotic disease caused by viruses belonging to the genus lyssavirus. In endemic countries of Asia and Africa, where the majority of the estimated 60,000 human rabies deaths occur, it is mainly caused by the classical rabies virus (RABV) transmitted by dogs. Over the last decade new species within the genus lyssavirus have been identified. Meanwhile 15 (proposed or classified) species exist, including Australian bat lyssavirus (ABLV), European bat lyssavirus (EBLV-1 and -2), Duvenhage virus (DUVV), as well as Lagos bat virus (LBV) and Mokola virus (MOKV) and recently identified novel species like Bokeloh bat lyssavirus (BBLV), Ikoma bat lyssavirus (IKOV) or Lleida bat lyssavirus (LLBV). The majority of these lyssavirus species are found in bat reservoirs and some have caused human infection and deaths. Previous work has demonstrated that Purified Chick Embryo Cell Rabies Vaccine (PCECV) not only induces immune responses against classical RABV, but also elicits cross-neutralizing antibodies against ABLV, EBLV-1 and EBLV-2. Using the same serum samples as in our previous study, this study extension investigated cross-neutralizing activities of serum antibodies measured by rapid fluorescent focus inhibition test (RFFIT) against selected other non-classical lyssavirus species of interest, namely DUVV and BBLV, as well as MOKV and LBV. Antibodies developed after vaccination with PCECV have neutralizing capability against BBLV and DUVV in the same range as against ABLV and EBLV-1 and -2. As expected, for the phylogenetically more distant species LBV no cross-neutralizing activity was found. Interestingly, 15 of 94 serum samples (16%) with a positive neutralizing antibody titer against RABV displayed specific cross-neutralizing activity (65-fold lower than against RABV) against one specific MOKV strain (Ethiopia isolate), which was not seen against a different strain (Nigeria isolate). Cross-neutralizing activities partly correlate with the

  7. Monoclonal antibodies for use in an immunoradiometric assay for α-foetoprotein

    International Nuclear Information System (INIS)

    Hunter, W.M.; Bennie, J.G.

    1982-01-01

    The advantages offered by a mouse IgG 1 monoclonal antibody to human α-foetoprotein (AFP) for the preparation of [ 125 I]antibody for use in an immunoradiometric assay (IRMA) have been investigated. The antibody was isolated from ascites fluid by sodium sulphate precipitation followed by gel filtration on Sephadex G-200. The freeze-dried powder and solutions thereof were stable and were used for iodination to 1 atom 125 I/molecule antibody by the chloramine-T procedure. At high antigen concentrations 70-80% of the added [ 125 ]Ab was present in the sandwich. Linear response curves in the range 1-100 μg antigen/l incubate were obtained when [ 125 I]Ab was in slight excess. In this region an Ag : Ab ratio 1.9 : 1 was obtained which is consistent with the saturation of a bifunctional antibody. Although non-specific binding (in the absence of antigen) was consistently 125 I]Ab, this was the main factor in determining assay detection limits. The serum AFP levels from both non-pregnant and pregnant subjects as measured by the IRMA using the [ 125 I]monoclonal Ab and by radioimmunoassay (RIA) using a sheep antiserum to AFP were in excellent agreement. The IRMA was manipulatively simple, employed a shorter incubation time (2h), required shorter counting times than the RIA and gave a much wider working range. The provision of a monoclonal antibody for labelling removes the one major practicability barrier which otherwise limits the development and use of the potentially superior IRMA system. (Auth.)

  8. Monoclonal antibodies for use in an immunoradiometric assay for. cap alpha. -foetoprotein

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, W.M.; Bennie, J.G. (Medical Research Council, Edinburgh (UK). Immunoassay Team); Brock, D.J.H.; Heyningen, V. van (Western General Hospital, Edinburgh (UK))

    1982-04-29

    The advantages offered by a mouse IgG/sub 1/ monoclonal antibody to human ..cap alpha..-foetoprotein (AFP) for the preparation of (/sup 125/I)antibody for use in an immunoradiometric assay (IRMA) have been investigated. The antibody was isolated from ascites fluid by sodium sulphate precipitation followed by gel filtration on Sephadex G-200. The freeze-dried powder and solutions thereof were stable and were used for iodination to 1 atom /sup 125/I/molecule antibody by the chloramine-T procedure. At high antigen concentrations 70-80% of the added (/sup 125/)Ab was present in the sandwich. Linear response curves in the range 1-100 ..mu..g antigen/l incubate were obtained when (/sup 125/I)Ab was in slight excess. In this region an Ag : Ab ratio 1.9 : 1 was obtained which is consistent with the saturation of a bifunctional antibody. Although non-specific binding (in the absence of antigen) was consistently <0.1% of added (/sup 125/I)Ab, this was the main factor in determining assay detection limits. The serum AFP levels from both non-pregnant and pregnant subjects as measured by the IRMA using the (/sup 125/I)monoclonal Ab and by radioimmunoassay (RIA) using a sheep antiserum to AFP were in excellent agreement. The IRMA was manipulatively simple, employed a shorter incubation time (2h), required shorter counting times than the RIA and gave a much wider working range. The provision of a monoclonal antibody for labelling removes the one major practicability barrier which otherwise limits the development and use of the potentially superior IRMA system.

  9. Structural basis for diverse N-glycan recognition by HIV-1-neutralizing V1-V2-directed antibody PG16

    Energy Technology Data Exchange (ETDEWEB)

    Pancera, Marie; Shahzad-ul-Hussan, Syed; Doria-Rose, Nicole A.; McLellan, Jason S.; Bailer, Robert T.; Dai, Kaifan; Loesgen, Sandra; Louder, Mark K.; Staupe, Ryan P.; Yang, Yongping; Zhang, Baoshan; Parks, Robert; Eudailey, Joshua; Lloyd, Krissey E.; Blinn, Julie; Alam, S. Munir; Haynes, Barton F.; Amin, Mohammed N.; Wang, Lai-Xi; Burton, Dennis R.; Koff, Wayne C.; Nabel, Gary J.; Mascola, John R.; Bewley, Carole A; Kwong, Peter D. [NIH; (Scripps); (Duke); (Maryland-MED); (IAVI)

    2013-08-05

    HIV-1 uses a diverse N-linked-glycan shield to evade recognition by antibody. Select human antibodies, such as the clonally related PG9 and PG16, recognize glycopeptide epitopes in the HIV-1 V1–V2 region and penetrate this shield, but their ability to accommodate diverse glycans is unclear. Here we report the structure of antibody PG16 bound to a scaffolded V1–V2, showing an epitope comprising both high mannose–type and complex-type N-linked glycans. We combined structure, NMR and mutagenesis analyses to characterize glycan recognition by PG9 and PG16. Three PG16-specific residues, arginine, serine and histidine (RSH), were critical for binding sialic acid on complex-type glycans, and introduction of these residues into PG9 produced a chimeric antibody with enhanced HIV-1 neutralization. Although HIV-1–glycan diversity facilitates evasion, antibody somatic diversity can overcome this and can provide clues to guide the design of modified antibodies with enhanced neutralization.

  10. 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.

  11. Evaluation of the neutral comet assay for detection of alpha-particle induced DNA-double-strand-breaks

    International Nuclear Information System (INIS)

    Hofbauer, Daniela

    2010-01-01

    Aim of this study was to differentiate DNA-double-strand-breaks from DNA-single-strand-breaks on a single cell level, using the comet assay after α- and γ-irradiation. Americium-241 was used as a alpha-irradiation-source, Caesium-137 was used for γ-irradiation. Because of technical problems with both the neutral and alkaline comet assay after irradiation of gastric cancer cells and human lymphocytes, no definite differentiation of DNA-damage was possible.

  12. Neutralization antibody response to booster/priming immunization with new equine influenza vaccine in Japan.

    Science.gov (United States)

    Yamanaka, Takashi; Nemoto, Manabu; Bannai, Hiroshi; Tsujimura, Koji; Matsumura, Tomio; Kokado, Hiroshi; Gildea, Sarah; Cullinane, Ann

    2018-03-02

    Equine influenza (EI) vaccine has been widely used. However, the causative EI virus (H3N8) undergoes continuous antigenic drift, and the vaccine strains must be periodically reviewed and if necessary, updated to maintain vaccine efficacy against circulating viruses. In 2016, the Japanese vaccine was updated by replacing the old viruses with the Florida sub-lineage Clade (Fc) 2 virus, A/equine/Yokohama/aq13/2010 (Y10). We investigated the virus neutralization (VN) antibody response to Fc2 viruses currently circulating in Europe, after booster or primary immunization with the new vaccine. These European viruses have the amino acid substitution A144V or I179V of the hemagglutinin. In horses that had previously received a primary course and bi-annual boosters with the old vaccine booster, immunization with the updated vaccine increased the VN antibody levels against the European Fc2 viruses as well as Y10. There were no significant differences in the VN titers against Y10 and the Fc2 viruses with A144V or I179V substitution in horses that had received a primary course of the updated vaccine. However, a mixed primary course where the first dose was the old vaccine and the second dose was the updated vaccine, reduced VN titers against the European viruses compared to that against Y10. In summary, the new vaccine affords horses protective level of VN titers against the Fc2 viruses carrying A144V or I179V substitution, but our results suggest that the combination of the old and new vaccines for primary immunization would not be optimum.

  13. Cleavage-Independent HIV-1 Trimers From CHO Cell Lines Elicit Robust Autologous Tier 2 Neutralizing Antibodies

    Directory of Open Access Journals (Sweden)

    Shridhar Bale

    2018-05-01

    Full Text Available Native flexibly linked (NFL HIV-1 envelope glycoprotein (Env trimers are cleavage-independent and display a native-like, well-folded conformation that preferentially displays broadly neutralizing determinants. The NFL platform simplifies large-scale production of Env by eliminating the need to co-transfect the precursor-cleaving protease, furin that is required by the cleavage-dependent SOSIP trimers. Here, we report the development of a CHO-M cell line that expressed BG505 NFL trimers at a high level of homogeneity and yields of ~1.8 g/l. BG505 NFL trimers purified by single-step lectin-affinity chromatography displayed a native-like closed structure, efficient recognition by trimer-preferring bNAbs, no recognition by non-neutralizing CD4 binding site-directed and V3-directed antibodies, long-term stability, and proper N-glycan processing. Following negative-selection, formulation in ISCOMATRIX adjuvant and inoculation into rabbits, the trimers rapidly elicited potent autologous tier 2 neutralizing antibodies. These antibodies targeted the N-glycan “hole” naturally present on the BG505 Env proximal to residues at positions 230, 241, and 289. The BG505 NFL trimers that did not expose V3 in vitro, elicited low-to-no tier 1 virus neutralization in vivo, indicating that they remained intact during the immunization process, not exposing V3. In addition, BG505 NFL and BG505 SOSIP trimers expressed from 293F cells, when formulated in Adjuplex adjuvant, elicited equivalent BG505 tier 2 autologous neutralizing titers. These titers were lower in potency when compared to the titers elicited by CHO-M cell derived trimers. In addition, increased neutralization of tier 1 viruses was detected. Taken together, these data indicate that both adjuvant and cell-type expression can affect the elicitation of tier 2 and tier 1 neutralizing responses in vivo.

  14. Mimotopes selected with neutralizing antibodies against multiple subtypes of influenza A

    Directory of Open Access Journals (Sweden)

    Zhong Yanwei

    2011-12-01

    Full Text Available Abstract Background The mimotopes of viruses are considered as the good targets for vaccine design. We prepared mimotopes against multiple subtypes of influenza A and evaluate their immune responses in flu virus challenged Balb/c mice. Methods The mimotopes of influenza A including pandemic H1N1, H3N2, H2N2 and H1N1 swine-origin influenza virus were screened by peptide phage display libraries, respectively. These mimotopes were engineered in one protein as multi- epitopes in Escherichia coli (E. coli and purified. Balb/c mice were immunized using the multi-mimotopes protein and specific antibody responses were analyzed using hemagglutination inhibition (HI assay and enzyme-linked immunosorbent assay (ELISA. The lung inflammation level was evaluated by hematoxylin and eosin (HE. Results Linear heptopeptide and dodecapeptide mimotopes were obtained for these influenza virus. The recombinant multi-mimotopes protein was a 73 kDa fusion protein. Comparing immunized infected groups with unimmunized infected subsets, significant differences were observed in the body weight loss and survival rate. The antiserum contained higher HI Ab titer against H1N1 virus and the lung inflammation level were significantly decreased in immunized infected groups. Conclusions Phage-displayed mimotopes against multiple subtypes of influenza A were accessible to the mouse immune system and triggered a humoral response to above virus.

  15. Structure-Based Design of Hepatitis C Virus Vaccines That Elicit Neutralizing Antibody Responses to a Conserved Epitope

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, Brian G.; Boucher, Elisabeth N.; Piepenbrink, Kurt H.; Ejemel, Monir; Rapp, Chelsea A.; Thomas, William D.; Sundberg, Eric J.; Weng, Zhiping; Wang, Yang; Diamond, Michael S.

    2017-08-09

    Despite recent advances in therapeutic options, hepatitis C virus (HCV) remains a severe global disease burden, and a vaccine can substantially reduce its incidence. Due to its extremely high sequence variability, HCV can readily escape the immune response; thus, an effective vaccine must target conserved, functionally important epitopes. Using the structure of a broadly neutralizing antibody in complex with a conserved linear epitope from the HCV E2 envelope glycoprotein (residues 412 to 423; epitope I), we performed structure-based design of immunogens to induce antibody responses to this epitope. This resulted in epitope-based immunogens based on a cyclic defensin protein, as well as a bivalent immunogen with two copies of the epitope on the E2 surface. We solved the X-ray structure of a cyclic immunogen in complex with the HCV1 antibody and confirmed preservation of the epitope conformation and the HCV1 interface. Mice vaccinated with our designed immunogens produced robust antibody responses to epitope I, and their serum could neutralize HCV. Notably, the cyclic designs induced greater epitope-specific responses and neutralization than the native peptide epitope. Beyond successfully designing several novel HCV immunogens, this study demonstrates the principle that neutralizing anti-HCV antibodies can be induced by epitope-based, engineered vaccines and provides the basis for further efforts in structure-based design of HCV vaccines.

    IMPORTANCEHepatitis C virus is a leading cause of liver disease and liver cancer, with approximately 3% of the world's population infected. To combat this virus, an effective vaccine would have distinct advantages over current therapeutic options, yet experimental vaccines have not been successful to date, due in part to the virus's high sequence variability leading to immune escape. In this study, we rationally designed several vaccine immunogens based on the structure of a conserved epitope that

  16. Comparison of monoclonal antibodies and tritiated ligands for estrogen receptor assays in 241 breast cancer cytosols

    International Nuclear Information System (INIS)

    Goussard, J.; Lechevrel, C.; Martin, P.M.; Roussel, G.

    1986-01-01

    Estrogen receptor determinations have been performed on 241 cytosols from 160 breast cancer tumors using both radioactive ligands ([ 3 H]-estradiol, [3H]R2858) and monoclonal antibodies (Abbott ER-EIA Kit) to compare the two methods and to evaluate the clinical usefulness of the new immunological, simplified assay. Intra- and interassay reproducibility of the enzyme immunoassay (EIA) method was studied during a 6-month period on 35 standard curves with 4 different batches of monoclonal antibodies. Intraassay coefficients of variation studied on duplicates were smaller than 5% in most cases and reproducibility of the curves showed coefficients of variation lower than 10% except for standard 0 and 5 fmol/ml. Pooled cytosols used as control for the dextran coated charcoal method had interassay variation coefficients between 3.8 and 11.4%. Reproducibility has been studied on clinical specimens assayed twice at two different periods with either EIA or dextran coated charcoal methods. Slopes obtained were 1.05 and 0.96, respectively. A good stability of EIA results was obtained with protein concentrations in the range 4-0.15 mg/ml cytosol. No significant effects of dithiothreitol or monothioglycerol (1 mM) on EIA and dextran coated charcoal assay were observed. Eighty breast cancer cytosols were assayed with both EIA and Scatchard analysis. The slope of the regression curve obtained was 1.04 (r = 0.963). Cytosols were assayed by EIA and by a saturating concentration of tritiated ligand (5 nM). With 153 cytosols the EIA/5 nM slope was 1.34 (r = 0.978). This slope can be compared with the slope Scatchard/5 nM obtained with 90 cytosols: 1.29 (r = 0.985). Absence of cross-reactivity of monoclonal ER antibodies with progesterone receptor was observed

  17. Pichia pastoris-Expressed Bivalent Virus-Like Particulate Vaccine Induces Domain III-Focused Bivalent Neutralizing Antibodies without Antibody-Dependent Enhancement in Vivo

    Directory of Open Access Journals (Sweden)

    Rahul Shukla

    2018-01-01

    Full Text Available Dengue, a significant public health problem in several countries around the world, is caused by four different serotypes of mosquito-borne dengue viruses (DENV-1, -2, -3, and -4. Antibodies to any one DENV serotype which can protect against homotypic re-infection, do not offer heterotypic cross-protection. In fact, cross-reactive antibodies may augment heterotypic DENV infection through antibody-dependent enhancement (ADE. A recently launched live attenuated vaccine (LAV for dengue, which consists of a mixture of four chimeric yellow-fever/dengue vaccine viruses, may be linked to the induction of disease-enhancing antibodies. This is likely related to viral interference among the replicating viral strains, resulting in an unbalanced immune response, as well as to the fact that the LAV encodes prM, a DENV protein documented to elicit ADE-mediating antibodies. This makes it imperative to explore the feasibility of alternate ADE risk-free vaccine candidates. Our quest for a non-replicating vaccine centered on the DENV envelope (E protein which mediates virus entry into the host cell and serves as an important target of the immune response. Serotype-specific neutralizing epitopes and the host receptor recognition function map to E domain III (EDIII. Recently, we found that Pichia pastoris-expressed DENV E protein, of all four serotypes, self-assembled into virus-like particles (VLPs in the absence of prM. Significantly, these VLPs displayed EDIII and elicited EDIII-focused DENV-neutralizing antibodies in mice. We now report the creation and characterization of a novel non-replicating recombinant particulate vaccine candidate, produced by co-expressing the E proteins of DENV-1 and DENV-2 in P. pastoris. The two E proteins co-assembled into bivalent mosaic VLPs (mVLPs designated as mE1E2bv VLPs. The mVLP, which preserved the serotype-specific antigenic integrity of its two component proteins, elicited predominantly EDIII-focused homotypic virus-neutralizing

  18. 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

  19. How-to-do-it: Immunological Assays for the Classroom 1. Enzyme Linked Immunosorbent Assay (ELISA): A Laboratory Tool for Demonstration of Antibody-Antigen Interaction.

    Science.gov (United States)

    Russo, A. J.; And Others

    1984-01-01

    Background information, list of required materials, and procedures are provided for an immunological assay which has been modified for use as a classroom/laboratory demonstration of antigen-antibody reaction. The assay is designed for a two and one-half hour laboratory period but may be modified for one hour laboratories. (JN)

  20. A simple and rapid Hepatitis A Virus (HAV titration assay based on antibiotic resistance of infected cells: evaluation of the HAV neutralization potency of human immune globulin preparations

    Directory of Open Access Journals (Sweden)

    Kaplan Gerardo G

    2008-12-01

    Full Text Available Abstract Background Hepatitis A virus (HAV, the causative agent of acute hepatitis in humans, is an atypical Picornaviridae that grows poorly in cell culture. HAV titrations are laborious and time-consuming because the virus in general does not cause cytopathic effect and is detected by immunochemical or molecular probes. Simple HAV titration assays could be developed using currently available viral construct containing selectable markers. Results We developed an antibiotic resistance titration assay (ARTA based on the infection of human hepatoma cells with a wild type HAV construct containing a blasticidin (Bsd resistance gene. Human hepatoma cells infected with the HAV-Bsd construct survived selection with 2 μg/ml of blasticidin whereas uninfected cells died within a few days. At 8 days postinfection, the color of the pH indicator phenol red in cell culture media correlated with the presence of HAV-Bsd-infected blasticidin-resistant cells: an orange-to-yellow color indicated the presence of growing cells whereas a pink-to-purple color indicated that the cells were dead. HAV-Bsd titers were determined by an endpoint dilution assay based on the color of the cell culture medium scoring orange-to-yellow wells as positive and pink-to-purple wells as negative for HAV. As a proof-of-concept, we used the ARTA to evaluate the HAV neutralization potency of two commercially available human immune globulin (IG preparations and a WHO International Standard for anti-HAV. The three IG preparations contained comparable levels of anti-HAV antibodies that neutralized approximately 1.5 log of HAV-Bsd. Similar neutralization results were obtained in the absence of blasticidin by an endpoint dilution ELISA at 2 weeks postinfection. Conclusion The ARTA is a simple and rapid method to determine HAV titers without using HAV-specific probes. We determined the HAV neutralization potency of human IG preparations in 8 days by ARTA compared to the 14 days required by the

  1. Comparison of agglutinating and neutralizing antibodies to serovar hardjo in sows immunized with two commercial whole culture polivalent anti-leptospira bacterins

    Science.gov (United States)

    Soto, Francisco Rafael Martins; Pinheiro, Sônia Regina; Morais, Zenaide Maria; Gonçales, Amane Paldês; de Azevedo, Sérgio Santos; Bernardi, Fernanda; Camargo, Sebastião Rodrigues; Vasconcellos, Silvio Arruda

    2008-01-01

    It was performed the comparison of the intensity and duration of agglutinating and neutralizing antibodies to serovar Hardjo in swines vaccinated with two commercial anti-leptospira bacterins. Sows no reactive to 24 Leptospira sp serovars in the microscopic agglutination test (MAT) were divided in three groups: Group A (n=08): received two vaccine A doses with 30 days interval, Group B (n=08) two vaccine B doses with 30 days interval and Group C (n=08): control no vaccinated against leptospirosis.Blood samples were collected each 30 days during six months following the first vaccination. The sera were tested by MAT and growth inhibition test (GIT) to serovar Hardjo in order to evaluate respectively agglutinating and neutralizing antibodies. It was found that neutralizing antibodies persisted for a longer time than the agglutinating ones and that the absence of agglutinating antibodies does not means in the absence of the neutralizing. The peaks of agglutinating antibodies was obtained at least 30 days earlier than that produced by neutralizing. The duration of both kinds of antibodies measured differed between the two bacterines tested. The period for inducing neutralizing antibodies against serovar Hardjo indicated that gilts must be immunized with two doses of whole culture anti-leptospira bacterines applied 30 days each other at least 90 days before the first mating. For the maintenance of hight levels of neutralizing antibodies the revaccinations must be performed every six months after the first vaccination. PMID:24031250

  2. Heterophilic antibody interference affecting multiple hormone assays: Is it due to rheumatoid factor?

    Science.gov (United States)

    Mongolu, Shiva; Armston, Annie E; Mozley, Erin; Nasruddin, Azraai

    2016-01-01

    Assay interference with heterophilic antibodies has been well described in literature. Rheumatoid factor is known to cause similar interference leading to falsely elevated hormone levels when measured by immunometric methods like enzyme-linked immunosorbent assay (ELISA) or multiplex immunoasays (MIA). We report a case of a 60-year-old male patient with a history of rheumatoid arthritis referred to our endocrine clinic for investigation of hypogonadism and was found to have high serum levels of LH, FSH, SHBG, Prolactin, HCG and TSH. We suspected assay interference and further tests were performed. We used Heteroblock tubes and PEG precipitation to eliminate the interference and the hormone levels post treatment were in the normal range. We believe the interference was caused by high serum levels of rheumatoid factor. Although he was treated with thyroxine for 3 years, we believe he may have been treated inappropriately as his Free T4 level was always normal despite high TSH due to assay interference. Our case illustrates the phenomenon of heterophilic antibody interference likely due to high levels of rheumatoid factor. It is essential for clinicians and endocrinologists in particular to be aware of this possibility when making treatment decisions in these groups of patients.

  3. Role of neutralizing antibodies and T-cells in pathogenesis of herpes simplex virus infection in congenitally athymic mice.

    Science.gov (United States)

    Kapoor, A K; Buckmaster, A; Nash, A A; Field, H J; Wildy, P

    1982-11-01

    Congenitally athymic nude mice were infected with 10(4) p.f.u. herpes simplex type 1 (strain SC16). Following the passive transfer of neutralizing monoclonal antibodies (AP7, AP8 and AP12) it was observed that AP7 alone reduced the virus infectivity in the nervous system; AP8 and AP12 failed to protect mice probably due to poor in vivo binding to the neutralization site on the virus. Latent ganglionic infection could be established in nude mice following adoptive transfer of optimum number (2 x 10(7) cells/mouse) of immune lymph node cells from day 7 herpes virus-infected hairy immunocompetent donor mice. Moreover, in some of the immune lymph node cell protected nudes, latency could be maintained even in complete absence of neutralizing antibodies. Results of ear-ablation experiments revealed that removal of primary source of infection after day 5 of infection reduced the amount of virus in the ganglia and spinal cord. Acute neurological infection was not detected following transfer of protective anti-gp-D neutralizing antibody (LP2) in combination with removal of infected pinna. These data suggest that continuous seeding of virus occurs in related ganglia via the axonal route from infected ear pinna. It appears that local T-cell-mediated immune mechanisms are involved in maintenance of latency.

  4. Smoking and risk of treatment-induced neutralizing antibodies to interferon β-1a.

    Science.gov (United States)

    Hedström, Anna Karin; Ryner, Malin; Fink, Katarina; Fogdell-Hahn, Anna; Alfredsson, Lars; Olsson, Tomas; Hillert, Jan

    2014-04-01

    Neutralizing antibodies (NAbs) to interferon β (IFNβ) products that develop during treatment are associated with a loss of clinical efficacy. The aim of this study was to investigate the influence of smoking habits on the risk of developing NAbs to IFNβ, in the treatment of multiple sclerosis (MS). This report is based on 695 MS patients treated with IFNβ-1a, included in two Swedish case-control studies that collected information on smoking habits. Using logistic regression, the development of NAbs to IFNβ-1a among current smokers was compared with that of non-smokers, by calculating the odds ratio (OR) with a 95% confidence interval (CI). Current smokers showed an increased risk of developing NAbs to IFNβ-1a, compared with non-smokers (OR 1.9; 95% CI 1.3-2.8; p = 0.002). There were no gender differences. We observed no association between past smoking and the risk of developing NAbs to IFNβ-1a. The finding that current smokers have an increased risk of developing NAbs to IFNβ-1a has implications, both for the practical care and the treatment of MS; it also provides an interesting perspective of the lungs as an immune-reactive organ, reacting upon irritation.

  5. Serum IFN neutralizing antibodies and neopterin levels in a cross-section of MS patients.

    Science.gov (United States)

    Cook, S D; Quinless, J R; Jotkowitz, A; Beaton, P

    2001-09-25

    To determine levels of serum interferon beta (IFNbeta) neutralizing antibody (NAb) and neopterin-an IFN biologic response marker-in patients with MS treated with Betaseron or Avonex. Controversy exists over the relative immunogenicity of IFNbeta-1a and IFNbeta-1b and the reasons for any such difference. To determine the role of patient profile and test methodology in IFNbeta, NAb levels need to be measured blindly and simultaneously in a predefined closely matched MS patient cohort. Serum NAb and neopterin levels were measured in closely matched patients on Avonex (n = 98) or Betaseron (n = 64). NAb were determined by Athena Diagnostics and serum neopterin levels by Covance Laboratories using a competitive binding radioimmunoassay. More patients taking Betaseron (22%) than Avonex (7%) had elevated titers of NAb (p = 0.008). Mean serum neopterin levels were lower in patients with high as compared to low NAb titers (p = 0.0002). No difference in mean neopterin levels was found comparing the total Betaseron group to the Avonex group; however, in the subset of patients with low NAb titers, mean neopterin levels were higher in the Betaseron than in the Avonex group (p = 0.027). A random cross-sectional sampling of patients on Avonex showed a decrease in neopterin levels over time between weekly doses. NAb are more commonly found with Betaseron than Avonex. More studies are needed to determine the correlation among serum neopterin levels, other biologic response markers, NAb, and disease activity in patients with MS being treated with IFNbeta.

  6. Neutralizing Antibodies to Enterovirus 71 in Belém, Brazil

    Directory of Open Access Journals (Sweden)

    Maria de Lourdes C Gomes

    2002-01-01

    Full Text Available Non-polio enteroviruses (Coxsackievirus A, Coxsackievirus B, Echovirus and EV 68-72 which belong to the enterovirus (EV genus, Picornaviridae family, may be responsible for acute flaccid paralysis, aseptic meningitis, myocarditis, hepatitis, pleurodinia, neonatal sepsis, hand, foot and mouth disease (HFMD even though 50-80% of infections are asymptomatic. EV 71 has been responsible for outbreaks and epidemics of HFMD and acute neurologic disease justifying its study in our country. The aim of this study was to detect neutralizing antibodies (NtAb to EV 71 in individuals up to 15 years of age living in Belém, State of Pará, northern Brazil. Serum samples from 238 patients attending the Virology Sector of Evandro Chagas Institute in Belém, Brazil, were analyzed using microneutralization tests that included RD cells and BrCr strain. Overall 40.8% (97/238 of tested samples had NtAb to EV 71. Regarding the distribution per age group, 85.2% (92/108 of patients aged 0-3 years had no NtAb to this virus and 69.2% of those 12 to15 years of age were seropositive. These results confirm that EV 71 infection occurs in the city of Belém; and that a high rate of individuals in this study were infected aged 3 years and over and, when aged 15 years nearly 70% had EV 71 NtAb.

  7. Comparison of multiple assays for detecting human antibodies directed against antigens on normal and malignant tissue culture cells

    International Nuclear Information System (INIS)

    Rosenberg, S.A.; Schwarz, S.; Anding, H.; Hyatt, C.; Williams, G.M.; Johns Hopkins Univ., Baltimore, Md.

    1977-01-01

    Four separate assays of human antibody reactivity to four separate normal and malignant human tissue culture cells lines from two patients have been evaluated using a single highly-reactive allogeneic serum. The visual end-point cytolysis assay and the chromium-51 release assay were equally sensitive in measuring complement mediated antibody cytotoxicity and both were far more sensitive than a trypan blue dye exclusion assay. The assay of antibody reactivity by hemadsorption technique was about 10 times more sensitive than any of the cytotoxicity assays. This latter assay measures only IgG antibody however. These assays showed that cell lines from different patients may differ greatly in 'reactivity' to an allogeneic serum and emphasized the importance of utilizing tumor and normal cells from the same patient when using tissue culture cells to search for tumor specific reactivity. These observations emphasize the importance of utilizing multiple assays against paired normal and malignant cells from the same patient to be certain of the specificity and magnitude of the measured antibody

  8. Selection of matched pair of monoclonal antibodies for development of immunoradiometric assay (IRMA) : our experience with IRMA of TSH

    International Nuclear Information System (INIS)

    Kadwad, V.B.; Jyotsna, N.; Sivaprasad, N.

    1998-01-01

    Full text: In immunoradiometricassay (IRMA) two antibodies raised against two different epitopes of the same antigen are used, one bound to a solid phase (capture antibody) and the other labelled with 125 I (detector antibody). The development of any IRMA thus involves proper selection of the capture and detector antibody, preparation of solid phase, labelling of the antibody and assay optimization. Extensive studies have been carried out on these aspects in our laboratory with greater emphasis on the behavior of different pairs of antibodies as sandwich partners : monoclonal-monoclonal and monoclonal-polyclonal antibodies. The parameters studied include the ease of radio-iodination of different monoclonal antibodies, the effect of interchange of capture and detector antibody etc. Keeping TSH antibody as a model, two different monoclonal antibodies, a polyclonal antibody and a tracer from a commercial TSH IRMA kit were used in this study. Based on our studies an assay procedure for in-house IRMA of TSH has been developed with a sensitivity of 0.1 μIU/ml and validated

  9. Enhanced inflammation in New Zealand white rabbits when MERS-CoV reinfection occurs in the absence of neutralizing antibody.

    Directory of Open Access Journals (Sweden)

    Katherine V Houser

    2017-08-01

    Full Text Available The Middle East respiratory syndrome coronavirus (MERS-CoV is a zoonotic betacoronavirus that was first detected in humans in 2012 as a cause of severe acute respiratory disease. As of July 28, 2017, there have been 2,040 confirmed cases with 712 reported deaths. While many infections have been fatal, there have also been a large number of mild or asymptomatic cases discovered through monitoring and contact tracing. New Zealand white rabbits are a possible model for asymptomatic infection with MERS-CoV. In order to discover more about non-lethal infections and to learn whether a single infection with MERS-CoV would protect against reinfection, we inoculated rabbits with MERS-CoV and monitored the antibody and inflammatory response. Following intranasal infection, rabbits developed a transient dose-dependent pulmonary infection with moderately high levels of viral RNA, viral antigen, and perivascular inflammation in multiple lung lobes that was not associated with clinical signs. The rabbits developed antibodies against viral proteins that lacked neutralizing activity and the animals were not protected from reinfection. In fact, reinfection resulted in enhanced pulmonary inflammation, without an associated increase in viral RNA titers. Interestingly, passive transfer of serum from previously infected rabbits to naïve rabbits was associated with enhanced inflammation upon infection. We further found this inflammation was accompanied by increased recruitment of complement proteins compared to primary infection. However, reinfection elicited neutralizing antibodies that protected rabbits from subsequent viral challenge. Our data from the rabbit model suggests that people exposed to MERS-CoV who fail to develop a neutralizing antibody response, or persons whose neutralizing antibody titers have waned, may be at risk for severe lung disease on re-exposure to MERS-CoV.

  10. PERFORMANCE EVALUATION OF A PROTOTYPE ARCHITECT ANTIBODY ASSAY FOR BABESIA MICROTI.

    Science.gov (United States)

    Cheng, Kevin; Coller, Kelly E; Marohnic, Christopher C; Pfeiffer, Zachary A; Fino, James R; Elsing, Randee R; Bergsma, Janet; Marcinkus, Marilee A; Kar, Alak K; Gumbs, Orlando H; Otis, Kathy S; Fishpaugh, Jeffrey; Schultz, Phillip W; Pope, Mark R; Narvaez, Alfredo R; Wong, Susan J; Madison-Antenucci, Susan; Leary, Thomas P; Dawson, George J

    2018-05-09

    The tick-borne protozoan Babesia microti is responsible for more than 200 cases of transfusion-transmitted babesiosis (TTB) infection in the United States over the last 30 years. Measures to mitigate the risk of TTB include nucleic acid testing (NAT) and B. microti antibody testing. A fully automated prototype B. microti antibody test was developed on the ARCHITECT instrument. The specificity was determined to be 99.98% in volunteer blood donors (n=28,740) from areas considered as low endemic for B. microti The sensitivity of the prototype test was studied in experimentally-infected macaques; a total of 128 samples were detected compared to 125 with the indirect fluorescent antibody test (IFA), additionally, 83 (89.2%) of the PCR positive samples were detected compared to 81 (87.1%) using the IFA test. All PCR positive samples that tested negative in the prototype antibody test were pre-seroconversion period samples. Following seroconversion, periods of intermittent parasitemia occurred; 17 PCR negative samples drawn in-between PCR positive bleed dates, tested positive both by the prototype test (robust reactivity) and IFA (marginal reactivity) prior to the administration of therapeutic drugs, indicating that the PCR test failed to detect samples from persistently infected macaques. The prototype assay detected 56 of 58 (96.6%) human subjects diagnosed with clinical babesiosis by both PCR and IFA testing. Overall, the prototype anti-babesia assay provides a highly sensitive and specific test for the diagnosis of B. microti infection. While PCR is preferred for detection of window period parasitemia, antibody tests detect infected subjects during periods of low level parasitemia. Copyright © 2018 Cheng et al.

  11. Comparison of a neutralization enzyme immunoassay and an enzyme-linked immunosorbent assay for evaluation of immune status of children vaccinated for mumps.

    Science.gov (United States)

    Harmsen, T; Jongerius, M C; van der Zwan, C W; Plantinga, A D; Kraaijeveld, C A; Berbers, G A

    1992-01-01

    A 50% neutralization enzyme immunoassay (N50-EIA) was compared with an indirect enzyme-linked immunosorbent assay (ELISA) for determining mumps virus antibodies in three consecutive serum samples from 138 children vaccinated with a live mumps vaccine at the age (in years) of 1.5. By the N50-EIA, most (132 of 138) preserum samples did not show neutralizing activity. Eight to 12 weeks after vaccination, 17 of the children were still negative, but only 7 remained so after 2.5 years, resulting in a seroconversion rate of 125 of 132 (95%). Over the same period, the neutralization geometric mean titer rose from 3.6 to 9.9. By an indirect ELISA, 128 of 138 preserum samples were found negative. The early and late postvaccination sera of 8 children were ELISA negative, resulting in a seroconversion rate of 120 of 128 (94%). Only two children remained seronegative by both methods. Seven of the late postvaccination serum samples yielded noncorresponding results, reflecting 95% correlation between both methods. Due to cross-reactivity with parainfluenza viruses, the ELISA proved to be less specific, but on the other hand, it showed a greater sensitivity than the N50-EIA. PMID:1500523

  12. Comparative Assessment of Anti-HLA Antibodies Using Two Commercially Available Luminex-Based Assays.

    Science.gov (United States)

    Clerkin, Kevin J; See, Sarah B; Farr, Maryjane A; Restaino, Susan W; Serban, Geo; Latif, Farhana; Li, Lingzhi; Colombo, Paolo C; Vlad, George; Ray, Bryan; Vasilescu, Elena R; Zorn, Emmanuel

    2017-11-01

    Allospecific anti-HLA antibodies (Abs) are associated with rejection of solid organ grafts. The 2 main kits to detect anti-HLA Ab in patient serum are commercialized by Immucor and One Lambda/ThermoFisher. We sought to compare the performance of both platforms. Background-adjusted mean fluorescence intensity (MFI) values were used from both platforms to compare sera collected from 125 pretransplant and posttransplant heart and lung transplant recipients. Most HLA class I (94.5%) and HLA class II (89%) Abs with moderate to high MFI titer (≥4000) were detected by both assays. A modest correlation was observed between MFI values obtained from the 2 assays for both class I ( r = 0.3, r 2 = 0.09, P < 0.0001) and class II Ab ( r = 0.707, r 2 = 0.5, P < 0.0001). Both assays detected anti-class I and II Ab that the other did not; however, no specific HLA allele was detected preferentially by either of the 2 assays. For a limited number of discrepant sera, dilution resulted in comparable reactivity profiles between the 2 platforms. Immucor and One Lambda/ThermoFisher assays have a similar, albeit nonidentical, ability to detect anti-HLA Ab. Although the correlation between the assays was present, significant variances exist, some of which can be explained by a dilution-sensitive "prozone" effect.

  13. Development of in vitro and in vivo rabies virus neutralization assays based on a high-titer pseudovirus system

    Science.gov (United States)

    Nie, Jianhui; Wu, Xiaohong; Ma, Jian; Cao, Shouchun; Huang, Weijin; Liu, Qiang; Li, Xuguang; Li, Yuhua; Wang, Youchun

    2017-01-01

    Pseudoviruses are useful virological tools because of their safety and versatility; however the low titer of these viruses substantially limits their wider applications. We developed a highly efficient pseudovirus production system capable of yielding 100 times more rabies pseudovirus than the traditional method. Employing the high-titer pseudoviruses, we have developed robust in vitro and in vivo neutralization assays for the evaluation of rabies vaccine, which traditionally relies on live-virus based assays. Compared with current rapid fluorescent focus inhibition test (RFFIT), our in vitro pseudovirus-based neutralization assay (PBNA) is much less labor-intensive while demonstrating better reproducibility. Moreover, the in vivo PBNA assay was also found to be superior to the live virus based assay. Following intravenous administration, the pseudovirus effectively infected the mice, with dynamic viral distributions being sequentially observed in spleen, liver and brain. Furthermore, data from in vivo PBNA showed great agreement with those generated from the live virus model but with the experimental time significantly reduced from 2 weeks to 3 days. Taken together, the effective pseudovirus production system facilitated the development of novel PBNA assays which could replace live virus-based traditional assays due to its safety, rapidity, reproducibility and high throughput capacity. PMID:28218278

  14. Limited diagnostic capacities of two commercial assays for the detection of Leptospira immunoglobulin M antibodies in Laos

    NARCIS (Netherlands)

    Blacksell, Stuart D.; Smythe, Lee; Phetsouvanh, Rattanaphone; Dohnt, Michael; Hartskeerl, Rudy; SymondS, Meegan; Slack, Andrew; Vongsouvath, Manivanh; Davong, Viengmone; Lattana, Olay; Phongmany, Simmaly; Keolouangkot, Valy; White, Nicholas J.; Day, Nicholas P. J.; Newton, Paul N.

    2006-01-01

    The diagnostic utility of immunochromatographic (Leptotek) and enzyme-linked immunosorbent assay (ELISA; Panbio) tests for the detection of Leptospira immunoglobulin M antibodies was assessed in febrile adults admitted in Vientiane, Laos. Both tests demonstrated poor diagnostic accuracy using

  15. 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...

  16. Two-monoclonal-antibody sandwich-type assay for thyrotropin, with use of an avidin-biotin separation technique

    International Nuclear Information System (INIS)

    Odell, W.D.; Griffin, J.; Zahradnik, R.

    1986-01-01

    We have developed a sensitive, specific, noncompetitive, sandwich-type radioimmunoassay for human thyrotropin (hTSH), which can be performed in 30 min. The assay involves two monoclonal antibodies, selected for high affinity and specificity and also for reaction against antigenic sites on hTSH that are distal from each other. One of these antibodies is labeled with 125 I; the other is conjugated covalently to biotin. Polystyrene beads were also conjugated covalently to biotin. After conjugation, the beads were incubated with avidin. These beads represent a rapid, simple method for separating hTSH-bound antibody from free antibody. The biotin-antibody-hTSH- 125 I-labeled antibody complexes bind to the beads and hTSH concentration is directly related to counts per minute. This assay can detect hTSH at a concentration of 0.06 milli-unit/L in serum

  17. Antibody screening by enzyme-linked immunosorbent assay using pooled soluble HLA in renal transplant candidates.

    Science.gov (United States)

    Zaer, F; Metz, S; Scornik, J C

    1997-01-15

    The enzyme-linked immunosorbent assay (ELISA) using HLA class I molecules purified from pooled platelets has the potential to detect HLA antibodies with increased efficiency without sacrificing sensitivity or specificity. This test, which was originally developed in our institution, has been independently validated by recent studies and is now commercially available. We now present evidence of its usefulness as a routine HLA antibody screening test for renal transplant patients. A total of 515 patients were tested monthly by ELISA (13.9 tests/patient) and by antiglobulin-enhanced panel reactivity (6.3 tests/patient). In patients found to be unsensitized, the incidence of false-positive results was less for ELISA than for the panel studies. In patients who were highly sensitized, both tests performed equally well, whereas discordant results were registered mainly in cases of mild sensitization. Because 66% of our patients were not sensitized, the ELISA was effective in reducing the number of more involved tests aimed at characterizing the antibodies. These results provide a foundation to use the pooled platelet HLA ELISA on a routine basis for HLA antibody screening.

  18. Molecular signatures of hemagglutinin stem-directed heterosubtypic human neutralizing antibodies against influenza A viruses.

    Directory of Open Access Journals (Sweden)

    Yuval Avnir

    2014-05-01

    Full Text Available Recent studies have shown high usage of the IGHV1-69 germline immunoglobulin gene for influenza hemagglutinin stem-directed broadly-neutralizing antibodies (HV1-69-sBnAbs. Here we show that a major structural solution for these HV1-69-sBnAbs is achieved through a critical triad comprising two CDR-H2 loop anchor residues (a hydrophobic residue at position 53 (Ile or Met and Phe54, and CDR-H3-Tyr at positions 98±1; together with distinctive V-segment CDR amino acid substitutions that occur in positions sparse in AID/polymerase-η recognition motifs. A semi-synthetic IGHV1-69 phage-display library screen designed to investigate AID/polη restrictions resulted in the isolation of HV1-69-sBnAbs that featured a distinctive Ile52Ser mutation in the CDR-H2 loop, a universal CDR-H3 Tyr at position 98 or 99, and required as little as two additional substitutions for heterosubtypic neutralizing activity. The functional importance of the Ile52Ser mutation was confirmed by mutagenesis and by BCR studies. Structural modeling suggests that substitution of a small amino acid at position 52 (or 52a facilitates the insertion of CDR-H2 Phe54 and CDR-H3-Tyr into adjacent pockets on the stem. These results support the concept that activation and expansion of a defined subset of IGHV1-69-encoded B cells to produce potent HV1-69-sBnAbs does not necessarily require a heavily diversified V-segment acquired through recycling/reentry into the germinal center; rather, the incorporation of distinctive amino acid substitutions by Phase 2 long-patch error-prone repair of AID-induced mutations or by random non-AID SHM events may be sufficient. We propose that these routes of B cell maturation should be further investigated and exploited as a pathway for HV1-69-sBnAb elicitation by vaccination.

  19. A sensitive monoclonal antibody-based enzyme-linked immunosorbent assay for chlorpyrifos residue determination in Chinese agricultural smaples

    Science.gov (United States)

    A monoclonal antibody-based competitive antibody-coated enzyme-linked immunosorbent assay (ELISA) was developed and optimized for determining chlorpyrifos residue in agricultural products. The IC50 and IC10 of this ELISA were 3.3 ng/mL and 0.1 ng/mL respectively. The average recoveries recovery rate...

  20. Quantification of patient specific assay interference in different formats of enzyme linked immunoassays for therapeutic monoclonal antibodies

    NARCIS (Netherlands)

    Grebenchtchikov, N.J.; Geurts-Moespot, A.; Heijmen, L.; Laarhoven, H.W.M. van; Herpen, C.M.L. van; Thijs, A.M.J.; Span, P.N.; Sweep, F.C.

    2014-01-01

    BackgroundThe use of therapeutic monoclonal antibodies for clinical purposes has significantly increased in recent years, and so has the need to monitor antibody concentrations. This may be achieved using the well-established enzyme linked immunoassay (ELISA) methods; however, these assays are

  1. Quantification of patient-specific assay interference in different formats of enzyme-linked immunoassays for therapeutic monoclonal antibodies

    NARCIS (Netherlands)

    Grebenchtchikov, Nicolai; Geurts-Moespot, Anneke J.; Heijmen, Linda; van Laarhoven, Hanneke W. M.; van Herpen, Carla M. L.; Thijs, Annemarie M. J.; Span, Paul N.; Sweep, Fred C. G. J.

    2014-01-01

    The use of therapeutic monoclonal antibodies for clinical purposes has significantly increased in recent years, and so has the need to monitor antibody concentrations. This may be achieved using the well-established enzyme linked immunoassay (ELISA) methods; however, these assays are subject to a

  2. Structural and Functional Characterization of Anti-A33 Antibodies Reveal a Potent Cross-Species Orthopoxviruses Neutralizer.

    Directory of Open Access Journals (Sweden)

    Michael H Matho

    2015-09-01

    Full Text Available Vaccinia virus A33 is an extracellular enveloped virus (EEV-specific type II membrane glycoprotein that is essential for efficient EEV formation and long-range viral spread within the host. A33 is a target for neutralizing antibody responses against EEV. In this study, we produced seven murine anti-A33 monoclonal antibodies (MAbs by immunizing mice with live VACV, followed by boosting with the soluble A33 homodimeric ectodomain. Five A33 specific MAbs were capable of neutralizing EEV in the presence of complement. All MAbs bind to conformational epitopes on A33 but not to linear peptides. To identify the epitopes, we have adetermined the crystal structures of three representative neutralizing MAbs in complex with A33. We have further determined the binding kinetics for each of the three antibodies to wild-type A33, as well as to engineered A33 that contained single alanine substitutions within the epitopes of the three crystallized antibodies. While the Fab of both MAbs A2C7 and A20G2 binds to a single A33 subunit, the Fab from MAb A27D7 binds to both A33 subunits simultaneously. A27D7 binding is resistant to single alanine substitutions within the A33 epitope. A27D7 also demonstrated high-affinity binding with recombinant A33 protein that mimics other orthopoxvirus strains in the A27D7 epitope, such as ectromelia, monkeypox, and cowpox virus, suggesting that A27D7 is a potent cross-neutralizer. Finally, we confirmed that A27D7 protects mice against a lethal challenge with ectromelia virus.

  3. Env-glycoprotein heterogeneity as a source of apparent synergy and enhanced cooperativity in inhibition of HIV-1 infection by neutralizing antibodies and entry inhibitors

    Science.gov (United States)

    Ketas, Thomas J.; Holuigue, Sophie; Matthews, Katie; Moore, John P.

    2011-01-01

    We measured the inhibition of infectivity of HIV-1 isolates and derivative clones by combinations of neutralizing antibodies (NAbs) and other entry inhibitors in a single-cycle-replication assay. Synergy was analyzed both by the current linear and a new nonlinear method. The new method reduced spurious indications of synergy and antagonism. Synergy between NAbs was overall weaker than between other entry inhibitors, and no stronger where one ligand is known to enhance the binding of another. However, synergy was stronger for a genetically heterogeneous HIV-1 R5 isolate than for its derivative clones. Enhanced cooperativity in inhibition by combinations, compared with individual inhibitors, correlated with increased synergy at higher levels of inhibition, while being less variable. Again, cooperativity enhancement was stronger for isolates than clones. We hypothesize that genetic, post-translational or conformational heterogeneity of the Env protein and of other targets for inhibitors can yield apparent synergy and increased cooperativity between inhibitors. PMID:22018634

  4. Precisely Molded Nanoparticle Displaying DENV-E Proteins Induces Robust Serotype-Specific Neutralizing Antibody Responses.

    Directory of Open Access Journals (Sweden)

    Stefan W Metz

    2016-10-01

    Full Text Available Dengue virus (DENV is the causative agent of dengue fever and dengue hemorrhagic fever. The virus is endemic in over 120 countries, causing over 350 million infections per year. Dengue vaccine development is challenging because of the need to induce simultaneous protection against four antigenically distinct DENV serotypes and evidence that, under some conditions, vaccination can enhance disease due to specific immunity to the virus. While several live-attenuated tetravalent dengue virus vaccines display partial efficacy, it has been challenging to induce balanced protective immunity to all 4 serotypes. Instead of using whole-virus formulations, we are exploring the potentials for a particulate subunit vaccine, based on DENV E-protein displayed on nanoparticles that have been precisely molded using Particle Replication in Non-wetting Template (PRINT technology. Here we describe immunization studies with a DENV2-nanoparticle vaccine candidate. The ectodomain of DENV2-E protein was expressed as a secreted recombinant protein (sRecE, purified and adsorbed to poly (lactic-co-glycolic acid (PLGA nanoparticles of different sizes and shape. We show that PRINT nanoparticle adsorbed sRecE without any adjuvant induces higher IgG titers and a more potent DENV2-specific neutralizing antibody response compared to the soluble sRecE protein alone. Antigen trafficking indicate that PRINT nanoparticle display of sRecE prolongs the bio-availability of the antigen in the draining lymph nodes by creating an antigen depot. Our results demonstrate that PRINT nanoparticles are a promising platform for delivering subunit vaccines against flaviviruses such as dengue and Zika.

  5. Structural basis for the binding of the neutralizing antibody, 7D11, to the poxvirus L1 protein

    International Nuclear Information System (INIS)

    Su, Hua-Poo; Golden, Joseph W.; Gittis, Apostolos G.; Hooper, Jay W.; Garboczi, David N.

    2007-01-01

    Medical countermeasures to prevent or treat smallpox are needed due to the potential use of poxviruses as biological weapons. Safety concerns with the currently available smallpox vaccine indicate a need for research on alternative poxvirus vaccine strategies. Molecular vaccines involving the use of proteins and/or genes and recombinant antibodies are among the strategies under current investigation. The poxvirus L1 protein, encoded by the L1R open reading frame, is the target of neutralizing antibodies and has been successfully used as a component of both protein subunit and DNA vaccines. L1-specific monoclonal antibodies (e.g., mouse monoclonal antibody mAb-7D11, mAb-10F5) with potent neutralizing activity bind L1 in a conformation-specific manner. This suggests that proper folding of the L1 protein used in molecular vaccines will affect the production of neutralizing antibodies and protection. Here, we co-crystallized the Fab fragment of mAb-7D11 with the L1 protein. The crystal structure of the complex between Fab-7D11 and L1 reveals the basis for the conformation-specific binding as recognition of a discontinuous epitope containing two loops that are held together by a disulfide bond. The structure of this important conformational epitope of L1 will contribute to the development of molecular poxvirus vaccines and also provides a novel target for anti-poxvirus drugs. In addition, the sequence and structure of Fab-7D11 will contribute to the development of L1-targeted immunotherapeutics

  6. Cross-reactive neutralizing antibody responses to enterovirus 71 infections in young children: implications for vaccine development.

    Directory of Open Access Journals (Sweden)

    Mei-Liang Huang

    Full Text Available BACKGROUND: Recently, enterovirus 71 (EV71 has caused life-threatening outbreaks involving neurological and cardiopulmonary complications in Asian children with unknown mechanism. EV71 has one single serotype but can be phylogenetically classified into 3 main genogroups (A, B and C and 11 genotypes (A, B1∼B5 and C1∼C5. In Taiwan, nationwide EV71 epidemics with different predominant genotypes occurred in 1998 (C2, 2000-2001 (B4, 2004-2005 (C4, and 2008 (B5. In this study, sera were collected to measure cross-reactive neutralizing antibody titers against different genotypes. METHODS: We collected historical sera from children who developed an EV71 infection in 1998, 2000, 2005, 2008, or 2010 and measured cross-reactive neutralizing antibody titers against all 11 EV71 genotypes. In addition, we aligned and compared the amino acid sequences of P1 proteins of the tested viruses. RESULTS: Serology data showed that children infected with genogroups B and C consistently have lower neutralizing antibody titers against genogroup A (>4-fold difference. The sequence comparisons revealed that five amino acid signatures (N143D in VP2; K18R, H116Y, D167E, and S275A in VP1 are specific for genogroup A and may be related to the observed antigenic variations. CONCLUSIONS: This study documented antigenic variations among different EV71 genogroups and identified potential immunodominant amino acid positions. Enterovirus surveillance and vaccine development should monitor these positions.

  7. Hepatitis C Virus E1 and E2 Proteins Used as Separate Immunogens Induce Neutralizing Antibodies with Additive Properties.

    Directory of Open Access Journals (Sweden)

    Elodie Beaumont

    Full Text Available Various strategies involving the use of hepatitis C virus (HCV E1 and E2 envelope glycoproteins as immunogens have been developed for prophylactic vaccination against HCV. However, the ideal mode of processing and presenting these immunogens for effective vaccination has yet to be determined. We used our recently described vaccine candidate based on full-length HCV E1 or E2 glycoproteins fused to the heterologous hepatitis B virus S envelope protein to compare the use of the E1 and E2 proteins as separate immunogens with their use as the E1E2 heterodimer, in terms of immunogenetic potential and the capacity to induce neutralizing antibodies. The specific anti-E1 and anti-E2 antibody responses induced in animals immunized with vaccine particles harboring the heterodimer were profoundly impaired with respect to those in animals immunized with particles harboring E1 and E2 separately. Moreover, the anti-E1 and anti-E2 antibodies had additive neutralizing properties that increase the cross-neutralization of heterologous strains of various HCV genotypes, highlighting the importance of including both E1 and E2 in the vaccine for an effective vaccination strategy. Our study has important implications for the optimization of HCV vaccination strategies based on HCV envelope proteins, regardless of the platform used to present these proteins to the immune system.

  8. Broad and potent HIV-1 neutralization by a human antibody that binds the gp41-gp120 interface

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Jinghe; Kang, Byong H.; Pancera, Marie; Lee, Jeong Hyun; Tong, Tommy; Feng, Yu; Imamichi, Hiromi; Georgiev, Ivelin S.; Chuang, Gwo-Yu; Druz, Aliaksandr; Doria-Rose, Nicole A.; Laub, Leo; Sliepen, Kwinten; van Gils, Marit J.; de la Peña, Alba Torrents; Derking, Ronald; Klasse, Per-Johan; Migueles, Stephen A.; Bailer, Robert T.; Alam, Munir; Pugach, Pavel; Haynes, Barton F.; Wyatt, Richard T.; Sanders, Rogier W.; Binley, James M.; Ward, Andrew B.; Mascola, John R.; Kwong, Peter D.; Connors, Mark [NIH

    2015-10-15

    The isolation of human monoclonal antibodies is providing important insights into the specificities that underlie broad neutralization of HIV-1 (reviewed in ref. 1). Here we report a broad and extremely potent HIV-specific monoclonal antibody, termed 35O22, which binds a novel HIV-1 envelope glycoprotein (Env) epitope. 35O22 neutralized 62% of 181 pseudoviruses with a half-maximum inhibitory concentration (IC50) <50 μg ml-1. The median IC50 of neutralized viruses was 0.033 μg ml-1, among the most potent thus far described. 35O22 did not bind monomeric forms of Env tested, but did bind the trimeric BG505 SOSIP.664. Mutagenesis and a reconstruction by negative-stain electron microscopy of the Fab in complex with trimer revealed that it bound to a conserved epitope, which stretched across gp120 and gp41. The specificity of 35O22 represents a novel site of vulnerability on HIV Env, which serum analysis indicates to be commonly elicited by natural infection. Binding to this new site of vulnerability may thus be an important complement to current monoclonal-antibody-based approaches to immunotherapies, prophylaxis and vaccine design.

  9. Detection of HLA Antibodies in Organ Transplant Recipients – Triumphs and Challenges of the Solid Phase Bead Assay

    Science.gov (United States)

    Tait, Brian D.

    2016-01-01

    This review outlines the development of human leukocyte antigen (HLA) antibody detection assays and their use in organ transplantation in both antibody screening and crossmatching. The development of sensitive solid phase assays such as the enzyme-linked immunosorbent assay technique, and in particular the bead-based technology has revolutionized this field over the last 10–15 years. This revolution however has created a new paradigm in clinical decision making with respect to the detection of low level pretransplant HLA sensitization and its clinical relevance. The relative sensitivities of the assays used are discussed and the relevance of conflicting inter-assay results. Each assay has its advantages and disadvantages and these are discussed. Over the last decade, the bead-based assay utilizing the Luminex® fluorocytometer instrument has become established as the “gold standard” for HLA antibody testing. However, there are still unresolved issues surrounding this technique, such as the presence of denatured HLA molecules on the beads which reveal cryptic epitopes and the issue of appropriate fluorescence cut off values for positivity. The assay has been modified to detect complement binding (CB) in addition to non-complement binding (NCB) HLA antibodies although the clinical relevance of the CB and NCB IgG isotypes is not fully resolved. The increase sensitivity of the Luminex® bead assay over the complement-dependent cytotoxicity crossmatch has permitted the concept of the “virtual crossmatch” whereby the crossmatch is predicted to a high degree of accuracy based on the HLA antibody specificities detected by the solid phase assay. Dialog between clinicians and laboratory staff on an individual patient basis is essential for correct clinical decision making based on HLA antibody results obtained by the various techniques. PMID:28018342

  10. Detection of anti-spermatozoal antibodies by a 125I-protein-A radioimmunological assay

    International Nuclear Information System (INIS)

    Czuppon, A.B.

    1985-01-01

    A newly developed solid-phase radioimmunobinding assay (RIBA) using detergent-solubilized sperm antigen has been used to evaluate anti-sperm antibodies. Results showed that none of the fertile females and males were positive in the RIBA, whereas approximately 6% of the females and 3% of the males with unexplained infertility were positive. These results are similar to those obtained using a chemically synthesized spermatozoal decapeptide antigen. The RIBA is simple to perform, requires no vital or intact spermatozoa, and large numbers of sera (up to 400) can be processed in one day with a total incubation time of 90 min. (Auth.)

  11. Pre-existing neutralizing antibody mitigates B cell dysregulation and enhances the Env-specific antibody response in SHIV-infected rhesus macaques.

    Directory of Open Access Journals (Sweden)

    Juan Pablo Jaworski

    Full Text Available Our central hypothesis is that protection against HIV infection will be powerfully influenced by the magnitude and quality of the B cell response. Although sterilizing immunity, mediated by pre-formed abundant and potent antibodies is the ultimate goal for B cell-targeted HIV vaccine strategies, scenarios that fall short of this may still confer beneficial defenses against viremia and disease progression. We evaluated the impact of sub-sterilizing pre-existing neutralizing antibody on the B cell response to SHIV infection. Adult male rhesus macaques received passive transfer of a sub-sterilizing amount of polyclonal neutralizing immunoglobulin (Ig purified from previously infected animals (SHIVIG or control Ig prior to intra-rectal challenge with SHIVSF162P4 and extensive longitudinal sampling was performed. SHIVIG treated animals exhibited significantly reduced viral load and increased de novo Env-specific plasma antibody. Dysregulation of the B cell profile was grossly apparent soon after infection in untreated animals; exemplified by a ≈50% decrease in total B cells in the blood evident 2-3 weeks post-infection which was not apparent in SHIVIG treated animals. IgD+CD5+CD21+ B cells phenotypically similar to marginal zone-like B cells were highly sensitive to SHIV infection, becoming significantly decreased as early as 3 days post-infection in control animals, while being maintained in SHIVIG treated animals, and were highly correlated with the induction of Env-specific plasma antibody. These results suggest that B cell dysregulation during the early stages of infection likely contributes to suboptimal Env-specific B cell and antibody responses, and strategies that limit this dysregulation may enhance the host's ability to eliminate HIV.

  12. Hidden Lineage Complexity of Glycan-Dependent HIV-1 Broadly Neutralizing Antibodies Uncovered by Digital Panning and Native-Like gp140 Trimer

    Directory of Open Access Journals (Sweden)

    Linling He

    2017-08-01

    Full Text Available Germline precursors and intermediates of broadly neutralizing antibodies (bNAbs are essential to the understanding of humoral response to HIV-1 infection and B-cell lineage vaccine design. Using a native-like gp140 trimer probe, we examined antibody libraries constructed from donor-17, the source of glycan-dependent PGT121-class bNAbs recognizing the N332 supersite on the HIV-1 envelope glycoprotein. To facilitate this analysis, a digital panning method was devised that combines biopanning of phage-displayed antibody libraries, 900 bp long-read next-generation sequencing, and heavy/light (H/L-paired antibodyomics. In addition to single-chain variable fragments resembling the wild-type bNAbs, digital panning identified variants of PGT124 (a member of the PGT121 class with a unique insertion in the heavy chain complementarity-determining region 1, as well as intermediates of PGT124 exhibiting notable affinity for the native-like trimer and broad HIV-1 neutralization. In a competition assay, these bNAb intermediates could effectively compete with mouse sera induced by a scaffolded BG505 gp140.681 trimer for the N332 supersite. Our study thus reveals previously unrecognized lineage complexity of the PGT121-class bNAbs and provides an array of library-derived bNAb intermediates for evaluation of immunogens containing the N332 supersite. Digital panning may prove to be a valuable tool in future studies of bNAb diversity and lineage development.

  13. Hidden Lineage Complexity of Glycan-Dependent HIV-1 Broadly Neutralizing Antibodies Uncovered by Digital Panning and Native-Like gp140 Trimer.

    Science.gov (United States)

    He, Linling; Lin, Xiaohe; de Val, Natalia; Saye-Francisco, Karen L; Mann, Colin J; Augst, Ryan; Morris, Charles D; Azadnia, Parisa; Zhou, Bin; Sok, Devin; Ozorowski, Gabriel; Ward, Andrew B; Burton, Dennis R; Zhu, Jiang

    2017-01-01

    Germline precursors and intermediates of broadly neutralizing antibodies (bNAbs) are essential to the understanding of humoral response to HIV-1 infection and B-cell lineage vaccine design. Using a native-like gp140 trimer probe, we examined antibody libraries constructed from donor-17, the source of glycan-dependent PGT121-class bNAbs recognizing the N332 supersite on the HIV-1 envelope glycoprotein. To facilitate this analysis, a digital panning method was devised that combines biopanning of phage-displayed antibody libraries, 900 bp long-read next-generation sequencing, and heavy/light (H/L)-paired antibodyomics. In addition to single-chain variable fragments resembling the wild-type bNAbs, digital panning identified variants of PGT124 (a member of the PGT121 class) with a unique insertion in the heavy chain complementarity-determining region 1, as well as intermediates of PGT124 exhibiting notable affinity for the native-like trimer and broad HIV-1 neutralization. In a competition assay, these bNAb intermediates could effectively compete with mouse sera induced by a scaffolded BG505 gp140.681 trimer for the N332 supersite. Our study thus reveals previously unrecognized lineage complexity of the PGT121-class bNAbs and provides an array of library-derived bNAb intermediates for evaluation of immunogens containing the N332 supersite. Digital panning may prove to be a valuable tool in future studies of bNAb diversity and lineage development.

  14. Using an improved phagocytosis assay to evaluate the effect of HIV on specific antibodies to pregnancy-associated malaria.

    Science.gov (United States)

    Ataíde, Ricardo; Hasang, Wina; Wilson, Danny W; Beeson, James G; Mwapasa, Victor; Molyneux, Malcolm E; Meshnick, Steven R; Rogerson, Stephen J

    2010-05-25

    Pregnant women residing in malaria endemic areas are highly susceptible to Plasmodium falciparum malaria, particularly during their first pregnancy, resulting in low birth weight babies and maternal anaemia. This susceptibility is associated with placental sequestration of parasitised red blood cells expressing pregnancy-specific variant surface antigens. Acquisition of antibodies against these variant surface antigens may protect women and their offspring. Functions of such antibodies may include prevention of placental sequestration or opsonisation of parasitised cells for phagocytic clearance. Here we report the development and optimisation of a new high-throughput flow cytometry-based phagocytosis assay using undifferentiated Thp-1 cells to quantitate the amount of opsonizing antibody in patient sera, and apply this assay to measure the impact of HIV on the levels of antibodies to a pregnancy malaria-associated parasite line in a cohort of Malawian primigravid women. The assay showed high reproducibility, with inter-experimental correlation of r(2) = 0.99. In primigravid women, concurrent malaria infection was associated with significantly increased antibodies, whereas HIV decreased the ability to acquire opsonising antibodies (Mann-Whitney ranksum: p = 0.013). This decrease was correlated with HIV-induced immunosuppression, with women with less than 350 x 10(6) CD4+ T- cells/L having less opsonising antibodies (coef: -11.95,P = 0.002). Levels of antibodies were not associated with protection from low birth weight or anaemia. This flow cytometry-based phagocytosis assay proved to be efficient and accurate for the measurement of Fc-receptor mediated phagocytosis-inducing antibodies in large cohorts. HIV was found to affect mainly the acquisition of antibodies to pregnancy-specific malaria in primigravidae. Further studies of the relationship between opsonising antibodies to malaria in pregnancy and HIV are indicated.

  15. Neutralizing antibodies in patients with chronic hepatitis C, genotype 1, against a panel of genotype 1 culture viruses

    DEFF Research Database (Denmark)

    Pedersen, Jannie; Jensen, Tanja B; Carlsen, Thomas H R

    2013-01-01

    , infection treated with pegylated interferon-α and ribavirin. Thirty-nine patients with chronic hepatitis C, genotype 1a or 1b, with either sustained virologic response (n = 23) or non-sustained virologic response (n = 16) were enrolled. Samples taken prior to treatment were tested for their ability...... to neutralize 6 different HCV genotype 1 cell culture recombinants (1a: H77/JFH1, TN/JFH1, DH6/JFH1; 1b: J4/JFH1, DH1/JFH1, DH5/JFH1). The results were expressed as the highest dilution yielding 50% neutralization (NAb50-titer). We observed no genotype or subtype specific differences in NAb50-titers between......The correlation of neutralizing antibodies to treatment outcome in patients with chronic hepatitis C virus (HCV) infection has not been established. The aim of this study was to determine whether neutralizing antibodies could be used as an outcome predictor in patients with chronic HCV, genotype 1...

  16. Enterovirus 71 Neutralizing Antibodies Seroepidemiological Research among Children in Guangzhou, China between 2014 and 2015: A Cross-Sectional Study.

    Science.gov (United States)

    Zhang, Dingmei; Chen, Yan; Chen, Xiashi; He, Zhenjian; Zhu, Xun; Hao, Yuantao

    2017-03-20

    A hand-foot-mouth disease outbreak occurred in 2014 around Guangdong. The purpose of this study was investigating the status and susceptibility of infectious neutralizing antibodies to enterovirus 71 among children so as to provide scientific evidence for the population immunity level of hand-foot-mouth disease and prepare for enterovirus 71 vaccination implementation. Serum specimens were collected from children in communities from January 2014 to March 2015 in Guangzhou. A total of 197 serum samples from children 1-5 years old were collected for this cross-sectional study via non-probabilistic sampling from the database of Chinese National Science and Technique Major Project. Neutralization activity was measured via micro neutralization test in vitro. The positive rate of enterovirus 71 neutralizing antibodies was 59.4%, whereas the geometric mean titre was 1:12.7. A statistically significant difference in true positive rates was found between different age groups but not between different genders. Being the most susceptible population of hand-foot-mouth disease, children under 3 years of age are more likely to be infected with enterovirus 71, and the immunity of children increases with increasing age. Further cohort studies should be conducted, and measures for prevention and vaccination should be taken.

  17. Enterovirus 71 Neutralizing Antibodies Seroepidemiological Research among Children in Guangzhou, China between 2014 and 2015: A Cross-Sectional Study

    Directory of Open Access Journals (Sweden)

    Dingmei Zhang

    2017-03-01

    Full Text Available A hand-foot-mouth disease outbreak occurred in 2014 around Guangdong. The purpose of this study was investigating the status and susceptibility of infectious neutralizing antibodies to enterovirus 71 among children so as to provide scientific evidence for the population immunity level of hand-foot-mouth disease and prepare for enterovirus 71 vaccination implementation. Serum specimens were collected from children in communities from January 2014 to March 2015 in Guangzhou. A total of 197 serum samples from children 1–5 years old were collected for this cross-sectional study via non-probabilistic sampling from the database of Chinese National Science and Technique Major Project. Neutralization activity was measured via micro neutralization test in vitro. The positive rate of enterovirus 71 neutralizing antibodies was 59.4%, whereas the geometric mean titre was 1:12.7. A statistically significant difference in true positive rates was found between different age groups but not between different genders. Being the most susceptible population of hand–foot–mouth disease, children under 3 years of age are more likely to be infected with enterovirus 71, and the immunity of children increases with increasing age. Further cohort studies should be conducted, and measures for prevention and vaccination should be taken.

  18. A two-site immunoradiometric assay for human pregnancy-associated plasma protein A (PAPP-A) using monoclonal antibodies

    International Nuclear Information System (INIS)

    Mowles, E.A.; Pinto-Furtado, L.G.; Bolton, A.E.

    1986-01-01

    A rapid, sensitive immunoradiometric assay has been developed for human pregnancy-associated plasma protein A (PAPP-A) using a purified mouse monoclonal antibody as the tracer and a rabbit polyclonal antibody to this protein in the solid-phase antibody preparation. The assay showed no measurable cross-reaction (< 0.1%) against a range of purified human placental proteins, and a good correlation with a previously described radioimmunoassay procedure when tested on samples taken throughout normal human pregnancies. No PAPP-A-like immunological activity could be detected in sera from non-pregnant women, confirming the absence of this protein from the circulation outside pregnancy. (Auth.)

  19. 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.

  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. The use of whole blood in a dipstick assay for detection of antibodies to Mycobacterium leprae: a field evaluation

    NARCIS (Netherlands)

    Bührer-Sekula, S.; Cunha, M. G.; Ferreira, W. A.; Klatser, P. R.

    1998-01-01

    We describe a further simplification of a dipstick assay for the detection of antibodies to phenolic glycolipid I of Mycobacterium leprae by using whole blood and evaluated the assay performance in the leprosy endemic area of Amazonas in Brazil. The agreement with the 'gold' standard ELISA was 94.9%

  2. Antibodies to the A27 protein of vaccinia virus neutralize and protect against infection but represent a minor component of Dryvax vaccine--induced immunity.

    Science.gov (United States)

    He, Yong; Manischewitz, Jody; Meseda, Clement A; Merchlinsky, Michael; Vassell, Russell A; Sirota, Lev; Berkower, Ira; Golding, Hana; Weiss, Carol D

    2007-10-01

    The smallpox vaccine Dryvax, which consists of replication-competent vaccinia virus, elicits antibodies that play a major role in protection. Several vaccinia proteins generate neutralizing antibodies, but their importance for protection is unknown. We investigated the potency of antibodies to the A27 protein of the mature virion in neutralization and protection experiments and the contributions of A27 antibodies to Dryvax-induced immunity. Using a recombinant A27 protein (rA27), we confirmed that A27 contains neutralizing determinants and that vaccinia immune globulin (VIG) derived from Dryvax recipients contains reactivity to A27. However, VIG neutralization was not significantly reduced when A27 antibodies were removed, and antibodies elicited by an rA27 enhanced the protection conferred by VIG in passive transfer experiments. These findings demonstrate that A27 antibodies do not represent the major fraction of neutralizing activity in VIG and suggest that immunity may be augmented by vaccines and immune globulins that include strong antibody responses to A27.

  3. A ''reverse'' solid-phase radio-immuno-assay for IgM-antibodies to hepatitis A virus

    International Nuclear Information System (INIS)

    Meurman, O.H.; Matter, L.; Krishna, R.V.; Krech, U.H.

    1981-01-01

    A ''reverse'' solid-phase radio-immuno-assay for IgM antibodies to hepatitis A virus (HAV) was developed. Anti-human IgM immunoglobulins were bound on the wells of polyvinylchloride microtiter plates. Serum specimens were incubated in the anti-human IgM coated wells and bound IgM antibodies were then assayed for antigen specificity by subsequent incubations with HAV antigen and 125 I-labelled human anti-HAV IgG. The test showed a high sensitivity and specificity for anti-HAV IgM antibodies. No false-positive reactions were observed either in the sera from patients with hepatobiliary disorders other than HAV infection or in the sera containing both rheumatoid factor and anti-HAV IgG antibodies. In acute HAV infections specific IgM antibodies were present already in the first specimens taken within a few days after the onset of jaundice. The persistence of the IgM antibodies was from 4 to 6 months. IgM antibody titers up to 1,000,000 were observed in the acute phase of HAV infection. In routine diagnostic work the titration of the sera was not necessary, since a reliable qualitative result was obtained by testing the sera in a single dilution of 1:100. A similar ''reverse'' immuno-assay principle may be adaptable for the diagnostic determination of IgM antibodies to different viral and microbial antigens. (author)

  4. Naturally selected hepatitis C virus polymorphisms confer broad neutralizing antibody resistance.

    Science.gov (United States)

    Bailey, Justin R; Wasilewski, Lisa N; Snider, Anna E; El-Diwany, Ramy; Osburn, William O; Keck, Zhenyong; Foung, Steven K H; Ray, Stuart C

    2015-01-01

    For hepatitis C virus (HCV) and other highly variable viruses, broadly neutralizing mAbs are an important guide for vaccine development. The development of resistance to anti-HCV mAbs is poorly understood, in part due to a lack of neutralization testing against diverse, representative panels of HCV variants. Here, we developed a neutralization panel expressing diverse, naturally occurring HCV envelopes (E1E2s) and used this panel to characterize neutralizing breadth and resistance mechanisms of 18 previously described broadly neutralizing anti-HCV human mAbs. The observed mAb resistance could not be attributed to polymorphisms in E1E2 at known mAb-binding residues. Additionally, hierarchical clustering analysis of neutralization resistance patterns revealed relationships between mAbs that were not predicted by prior epitope mapping, identifying 3 distinct neutralization clusters. Using this clustering analysis and envelope sequence data, we identified polymorphisms in E2 that confer resistance to multiple broadly neutralizing mAbs. These polymorphisms, which are not at mAb contact residues, also conferred resistance to neutralization by plasma from HCV-infected subjects. Together, our method of neutralization clustering with sequence analysis reveals that polymorphisms at noncontact residues may be a major immune evasion mechanism for HCV, facilitating viral persistence and presenting a challenge for HCV vaccine development.

  5. Two different mutations in the envelope protein of feline immunodeficiency virus allow the virus to escape from neutralization by feline serum antibodies.

    NARCIS (Netherlands)

    C.H.J. Siebelink (Kees); M.L. Bosch (Marnix); G.F. Rimmelzwaan (Guus); R.H. Meloen; A.D.M.E. Osterhaus (Albert)

    1995-01-01

    textabstractViral progeny of two molecular clones of feline immunodeficiency virus (FIV), 19k1 and 19k32, were tested in a virus neutralization assay. In this assay the infection of thymocytes with FIV19k1 was neutralized by serum S1422, derived from an SPF cat 22 weeks after infection with FIV19k1.

  6. 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.

  7. 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

  8. Measurement of anti-IgA antibodies by a two-site immunoradiometric assay

    International Nuclear Information System (INIS)

    Homburger, H.A.; Smith, J.R.; Jacob, G.L.; Laschinger, C.; Naylor, D.H.; Pineda, A.A.

    1981-01-01

    To enable the detection of IgG class, anti-IgA antibodies and to investigate the possible occurrence of IgE class, anti-IgA antibodies, we developed a solid phase immunoradiometric assay, which uses purified IgA coupled covalently to microcrystalline cellulose as an immunosorbent. Radiolabeled, Fc specific anti-IgG and anti-IgE antibodies were used to detect specific aIgA after incubation of test sera or controls with the immunosorbent. IgG-aIgA were detected by the IRA in 100 and 67% of control sera with class specific and limited specificity aIgA. The IRA was sensitive to approximately two ng of class specific IgG-aIgA. IgG-aIgA also were detected by IRA in 7.9% of sera from patients with urticarial transfusion reactions and 73% of sera from patients with ataxia telangiectasia and IgA deficiency. Sera from 50 normal blood donors did not have detectable IgG-aIgA. Tests for IgE-aIgA were negative in all cases, including control sera with class specific IgG-aIgA. We conclude that the IRA is a sensitive and reproducible method for detection of class specific and limited specificity IgG-aIgA, and that IgE-aIgA do not mediate urticarial transfusion reactions

  9. Magnetic nanoparticle based purification and enzyme-linked immunosorbent assay using monoclonal antibody against enrofloxacin

    Science.gov (United States)

    Kim, Nam-Gun; Kim, Myeong-Ae; Park, Young-Il; Jung, Tae-Sung; Son, Seong-Wan; So, ByungJae

    2015-01-01

    Monoclonal anti-enrofloxacin antibody was prepared for a direct competitive enzyme-linked immunosorbent assay (ELISA) and purification system using monoclonal antibody (mAb) coupled magnetic nanoparticles (MNPs). The IC50 values of the developed mAb for enrofloxacin (ENR), ciprofloxacin, difloxacin, sarafloxacin, pefloxacin, and norfloxacin were 5.0, 8.3, 9.7, 21.7, 36.0, and 63.7 ng/mL, respectively. The lowest detectable level of ENR was 0.7 ng/mL in the prepared ELISA system. To validate the developed ELISA in the food matrix, known amounts of ENR were spiked in meat and egg samples at 10, 20 and 30 ng/mL. Recoveries for ENR ranged from 72.9 to 113.16% with a coefficient of variation (CV) of 2.42 to 10.11%. The applicability of the mAb-MNP system was verified by testing the recoveries for ENR residue in three different matrices. Recoveries for ENR ranged from 75.16 to 86.36%, while the CV ranged from 5.08 to 11.53%. Overall, ENR-specific monoclonal antibody was prepared and developed for use in competitive to ELISAs for the detection of ENR in animal meat samples. Furthermore, we suggest that a purification system for ENR using mAb-coupled MNPs could be useful for determination of ENR residue in food. PMID:26040610

  10. Cooperativity in virus neutralization by human monoclonal antibodies to two adjacent regions located at the amino terminus of hepatitis C virus E2 glycoprotein

    DEFF Research Database (Denmark)

    Keck, Zhenyong; Wang, Wenyan; Wang, Yong

    2013-01-01

    A challenge for hepatitis C virus (HCV) vaccine development is defining conserved epitopes that induce protective antibodies against this highly diverse virus. An envelope glycoprotein (E2) segment located at amino acids (aa) 412 to 423 contains highly conserved neutralizing epitopes. While...... at higher concentrations. However, the overall effect was additive neutralization. A similar pattern was observed when these antibodies were combined to block E2 binding to the HCV coreceptor, CD81. These findings demonstrate that both of these E2 regions participate in epitopes mediating virus...... (HCVcc) with various activities. Although nonneutralizing HC33 HMAbs were isolated, they had lower binding affinities than neutralizing HC33 HMAbs. These antibodies could be converted to neutralizing antibodies by affinity maturation. Unidirectional competition for binding to E2 was observed between HC33...

  11. Development and validation of receptor occupancy pharmacodynamic assays used in the clinical development of the monoclonal antibody vedolizumab.

    Science.gov (United States)

    Wyant, Tim; Estevam, Jose; Yang, Lili; Rosario, Maria

    2016-03-01

    Vedolizumab is a monoclonal antibody approved for use in ulcerative colitis and Crohn's disease. By specifically binding to α4 β7 integrin, vedolizumab prevents trafficking of lymphocytes to the gut, thereby interfering with disease pathology. During the clinical development program, the pharmacodynamic effect of vedolizumab was evaluated by 2 flow cytometry receptor occupancy assays: act-1 (ACT-1) and mucosal addressin cell adhesion molecule-1 (MAdCAM-1). Here we describe the development and validation of these assays. The ACT-1 assay is a receptor occupancy free-site assay that uses a monoclonal antibody with the same binding epitope as vedolizumab to detect free (unbound) sites on α4 β7 integrin. The MAdCAM-1 assay used a soluble version of the natural ligand for α4 β7 integrin to detect free sites. The assays were validated using a fit-for-purpose approach throughout the clinical development of vedolizumab. Both the ACT-1 assay and the MAdCAM-1 assay demonstrated acceptable reproducibility and repeatability. The assays were sufficiently stable to allow for clinical use. During clinical testing the assays demonstrated that vedolizumab was able to saturate peripheral cells at all doses tested. Two pharmacodynamic receptor occupancy assays were developed and validated to assess the effect of vedolizumab on peripheral blood cells. The results of these assays demonstrated the practical use of flow cytometry to examine pharmacodynamic response in clinical trials. © 2015 International Clinical Cytometry Society.

  12. 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

    and from herds declared free of infection with Ap. The Ap serotype 12 blocking ELISA showed a herd sensitivity of 0.77 (95% confidence interval, 0.62-0.88) and a herd specificity of 1.00 (0.95-1.00) with a cut-off value at 40% relative absorbance or 60% inhibition. The assay may be used advantageously......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...... 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...

  13. Increased specificity in human cardiac-myosin radioimmunoassay utilizing two monoclonal antibodies in a double sandwich assay

    International Nuclear Information System (INIS)

    Katus, H.A.; Hurrell, J.G.; Matsueda, G.R.; Ehrlich, P.; Zurawski, V.R. Jr.; Khaw, B.-A.; Haber, E.

    1982-01-01

    An immunoradiometric assay that simultaneously measured two different epitopes on the same molecule was devised to differential between cardiac- and skeletal-myosin light chains. Three monoclonal antibodies were examined that were 100% (lC5), 25% (2B9) and 17% (4F10) cross reactive, respectively, between the two antigens. One antibody of the pair to be studied was immobilized to cyanogen bromide-activated Sepharose 4B while the other was iodinated with 125 I using the lactoperoxidase method. The antigen was mixed with the immobilized antibody, the labeled antibody was added and the precipitate then washed and counted in a gamma counter. When both antibodies of the pair to be studied (immobilized and labeled) were the same (2B9), no radioactivity above background was bound to the precipitate, indicating that the second antibody could not bind to an already occupied epitope. When two different antibodies were employed, the specificity of the assay increased over that of a single antibody. The cross reactivity of a pair approximated the product of the cross reactivities of the individual antibodies. Thus, lC5 and 2B9 were 25% cross reactive together, lC5 and 4F10 17% cross reactive, and 2B9 and 4F10 4.3% cross reactive. (author)

  14. Neutralization of tier-2 viruses and epitope profiling of plasma antibodies from human immunodeficiency virus type 1 infected donors from India.

    Directory of Open Access Journals (Sweden)

    Raiees Andrabi

    Full Text Available Broadly cross neutralizing antibodies (NAbs are generated in a group of HIV-1 infected individuals during the natural infection, but little is known about their prevalence in patients infected with viral subtypes from different geographical regions. We tested here the neutralizing efficiency of plasma antibodies from 80 HIV-1 infected antiretroviral drug naive patients against a panel of subtype-B and C tier 2 viruses. We detected cross-neutralizing antibodies in approximately 19-27% of the plasma, however the subtype-C specific neutralization efficiency predominated (p = 0.004. The neutralizing activity was shown to be exclusively mediated by the immunoglobulin G (IgG fraction in the representative plasma samples. Epitope mapping of three, the most cross-neutralizing plasma (CNP AIIMS206, AIIMS239 and AIIMS249 with consensus-C overlapping envelope peptides revealed ten different binding specificities with only V3 and IDR being common. The V3 and IDR were highly antigenic regions but no correlation between their reciprocal Max50 binding titers and neutralization was observed. In addition, the neutralizing activity of CNP was not substantially reduced by V3 and gp41 peptides except a modest contribution of MPER peptide. The MPER was rarely recognized by plasma antibodies though antibody depletion and competition experiments demonstrated MPER dependent neutralization in two out of three CNP. Interestingly, the binding specificity of one of the CNP (AIIMS206 overlapped with broadly neutralizing mAb 2F5 epitope. Overall, the data suggest that, despite the low immunogenicity of HIV-1 MPER, the antibodies directed to this region may serve as crucial reagents for HIV-1 vaccine design.

  15. HIV-1 specific antibody titers and neutralization among chronically infected patients on long-term suppressive antiretroviral therapy (ART: a cross-sectional study.

    Directory of Open Access Journals (Sweden)

    Johannes S Gach

    Full Text Available The majority of potent and broadly neutralizing antibodies against HIV-1 have been isolated from untreated patients with acute or chronic infection. To assess the extent of HIV-1 specific antibody response and neutralization after many years of virologic suppression from potent combination ART, we examined antibody binding titers and neutralization of 51 patients with chronic HIV-1 infection on suppressive ART for at least three years. In this cross-sectional analysis, we found high antibody titers against gp120, gp41, and the membrane proximal external region (MPER in 59%, 43%, and 27% of patients, respectively. We observed significantly higher endpoint binding titers for gp120 and gp41 for patients with >10 compared to ≤ 10 years of detectable HIV RNA. Additionally, we observed higher median gp120 and gp41 antibody titers in patients with HIV RNA 10 years of detectable HIV RNA (8/20 [40.0%] versus 3/31 [9.7%] for ≤ 10 years, p = 0.02 and a trend toward greater neutralization in patients with ≤ 5 years of HIV RNA 5 years, p = 0.08. All patients with neutralizing activity mediated successful phagocytosis of VLPs by THP-1 cells after antibody opsonization. Our findings of highly specific antibodies to several structural epitopes of HIV-1 with antibody effector functions and neutralizing activity after long-term suppressive ART, suggest continuous antigenic stimulation and evolution of HIV-specific antibody response occurs before and after suppression with ART. These patients, particularly those with slower HIV progression and more time with detectable viremia prior to initiation of suppressive ART, are a promising population to identify and further study functional antibodies against HIV-1.

  16. Comparison of two assays for detection of antibodies against canine parvovirus and canine distemper virus in dogs admitted to a Florida animal shelter.

    Science.gov (United States)

    Gray, Lauren K; Crawford, P Cynda; Levy, Julie K; Dubovi, Edward J

    2012-05-01

    To compare 2 assays for use in the identification of dogs with a protective antibody titer (PAT) against canine parvovirus (CPV) and canine distemper virus (CDV). Prospective cross-sectional study. 431 dogs admitted to a municipal animal shelter in north central Florida. Blood samples were collected from dogs on the day of admission to the shelter. Serum was obtained, criterion-referenced assays were used to identify dogs that had PATs against CPV (titers ≥ 80; hemagglutination inhibition assay) and CDV (titers ≥ 32; virus neutralization assay), and results were compared with results of a semiquantitative ELISA and an immunofluorescence assay (IFA). For correct identification of dogs that had PATs against viruses, the ELISA had significantly higher specificity for CPV (98%) and CDV (95%) than did the IFA (82% and 70%, respectively) and had significantly lower sensitivity for CDV (88%) than did the IFA (97%); the sensitivity for CPV was similar (ELISA, 98%; IFA, 97%). Overall diagnostic accuracy was significantly greater with the ELISA than with the IFA. Predictive value of a positive result for PATs was significantly higher with the ELISA for CPV (99%) and CDV (93%) than with the IFA (92% and 71%, respectively). The ELISA had fewer false-positive results than did the IFA and could be performed on-site in shelters in < 1 hour. Accuracy and practicality of the ELISA may be useful for identifying the infection risk of dogs exposed during outbreaks attributable to CPV and CDV infections in shelters.

  17. pH-induced conformational change of the rotavirus VP4 spike: implications for cell entry and antibody neutralization.

    Science.gov (United States)

    Pesavento, Joseph B; Crawford, Sue E; Roberts, Ed; Estes, Mary K; Prasad, B V Venkataram

    2005-07-01

    The rotavirus spike protein, VP4, is a major determinant of infectivity and neutralization. Previously, we have shown that trypsin-enhanced infectivity of rotavirus involves a transformation of the VP4 spike from a flexible to a rigid bilobed structure. Here we show that at elevated pH the spike undergoes a drastic, irreversible conformational change and becomes stunted, with a pronounced trilobed appearance. These particles with altered spikes, at a normal pH of 7.5, despite the loss of infectivity and the ability to hemagglutinate, surprisingly exhibit sialic acid (SA)-independent cell binding in contrast to the SA-dependent cell binding exhibited by native virions. Remarkably, a neutralizing monoclonal antibody that remains bound to spikes throughout the pH changes (pH 7 to 11 and back to pH 7) completely prevents this conformational change, preserving the SA-dependent cell binding and hemagglutinating functions of the virion. A hypothesis that emerges from the present study is that high-pH treatment triggers a conformational change that mimics a post-SA-attachment step to expose an epitope recognized by a downstream receptor in the rotavirus cell entry process. This process involves sequential interactions with multiple receptors, and the mechanism by which the antibody neutralizes is by preventing this conformational change.

  18. An Improved Neutral a-Glucosidase Assay for Assessment of Epididymal Function—Validation and Comparison to the WHO Method

    Directory of Open Access Journals (Sweden)

    Frank Eertmans

    2014-01-01

    Full Text Available Neutral a-glucosidase (NAG activity in human seminal plasma is an important indicator for epididymis functionality. In the present study, the classic World Health Organization (WHO method has been adapted to enhance assay robustness. Changes include modified enzyme reaction buffer composition and usage of an alternative enzyme inhibitor for background correction (glucose instead of castanospermine. Both methods have been tested in parallel on 144 semen samples, obtained from 94 patients/donors and 50 vasectomized men (negative control, respectively. Passing-Bablok regression analysis demonstrated equal assay performance. In terms of assay validation, analytical specificity, detection limit, measuring range, precision, and cut-off values have been calculated. These data confirm that the adapted method is a reliable, improved tool for NAG analysis in human semen.

  19. A comparison of sperm agglutination and immobilization assays with a quantitative ELISA for anti-sperm antibody in serum.

    Science.gov (United States)

    Lynch, D M; Leali, B A; Howe, S E

    1986-08-01

    An enzyme-linked immunosorbent assay (ELISA) that quantitates antisperm antibody in serum was compared with standard sperm agglutination and immobilization assays with the use of sera from 40 normal and 292 subfertile individuals. Quantitation of the assay was accomplished by standardizing assay parameters, including the incorporation of a standard reference curve, the number of whole target sperm, the optimal dilution of serum, the selection of microtiter plate, and the time and temperatures involved in the adsorption and incubation phases. With this method, the level of antisperm antibody binding to target sperm in 40 normal fertile individuals was found to be 2.3 (+/- 1.1 standard deviation [SD]) fg immunoglobulin (Ig)/sperm. An increased mean level of 7.4 +/- 3.7 fg Ig/sperm was determined in 84 infertile patients with positive agglutination and/or immobilization tests. In 208 individuals with negative agglutination and immobilization tests the mean concentration of antisperm antibody was 2.5 +/- 1.3 fg Ig/sperm. Postvasectomy patients assayed by this method had a mean Ig binding value of 7.1 +/- 2.4 fg Ig/sperm. The infertile group with positive agglutination and/or immobilization tests had a significantly higher mean antisperm antibody level than the normal fertile group, according to the Student's t-test for independent samples (P less than 0.001). This indirect serum-based assay reproducibly quantitates antisperm antibody binding to whole target sperm, suggests the normal and abnormal levels of antisperm antibody, and correlates with standard functional assays.

  20. Immunoglobulin with High-Titer In Vitro Cross-Neutralizing Hepatitis C Virus Antibodies Passively Protects Chimpanzees from Homologous, but Not Heterologous, Challenge

    DEFF Research Database (Denmark)

    Bukh, Jens; Engle, Ronald E.; Faulk, Kristina

    2015-01-01

    The importance of neutralizing antibodies (NAbs) in protection against hepatitis C virus (HCV) remains controversial. We infused a chimpanzee with H06 immunoglobulin from a genotype 1a HCV-infected patient and challenged with genotype strains efficiently neutralized by H06 in vitro. Genotype 1a...

  1. Comparison of neutralizing and hemagglutination-inhibiting antibody responses to influenza A virus vaccination of human immunodeficiency virus-infected individuals

    NARCIS (Netherlands)

    Benne, CA; Harmsen, M; Tavares, L; Kraaijeveld, CA; De Jong, JC

    A neutralization enzyme immunoassay (N-EIA) was used to determine the neutralizing serum antibody titers to influenza A/Taiwan/1/86 (H1N1) and Beijing/353/89 (H3N2) viruses after vaccination of 51 human immunodeficiency virus (HIV) type 1-infected individuals and 10 healthy noninfected controls

  2. Hepatitis C virus expressing flag-tagged envelope protein 2 has unaltered infectivity and density, is specifically neutralized by flag antibodies and can be purified by affinity chromatography

    DEFF Research Database (Denmark)

    Prentø, Jannick Cornelius; Bukh, Jens

    2011-01-01

    to the original virus. Flag-tagged virus was susceptible to flag-specific antibody neutralization, and infected cells could be immuno-stained by anti-flag antibodies. Using affinity chromatography with anti-flag resin we repeatedly obtained ~30% recovery of infectious particles. The full viability and unaltered...

  3. A three-layer immunoradiometric assay for antibodies in different immunoglobulin classes and its application to the detection of chicken thyroglobulin autoantibodies and of antibodies to sheep erythrocytes

    International Nuclear Information System (INIS)

    Carvalho, L.C.P. de; Roitt, I.M.; Wick, G.

    1980-01-01

    A versatile solid-phase assay for detection of antibodies in different immunoglobulin classes is described. The assay has been applied to: (1) the detection of IgG and IgM antithyroglobulin autoantibodies in chickens with spontaneous autoimmune thyroiditis, and (2) the detection of anti-sheep cell antibodies in normal chickens. Thyroglobulin-coated plastic tubes or formaldehyde-fixed sheep erythrocytes were used as the solid phase. Antisera were added in succession to the solid-phase antigen so as to form 3 antibody layers: (1) chicken antibody against the solid-phase antigen; (2) heavy-chain-specific rabbit anti-chicken immunoglobulin; and (3) 125 I-labelled goat anti-rabbit immunoglobulin. The assay is suitable for routine determinations on large numbers of samples; its sensitivity enables small volumes of serum to be tested and allows considerable economy in the use of valuable class-specific antisera. The radiolabelled reagent can be readily applied to other assays employing rabbit antisera. (Auth.)

  4. 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...

  5. HCMV Infection of Human Trophoblast Progenitor Cells of the Placenta Is Neutralized by a Human Monoclonal Antibody to Glycoprotein B and Not by Antibodies to the Pentamer Complex

    Directory of Open Access Journals (Sweden)

    Martin Zydek

    2014-03-01

    Full Text Available Human cytomegalovirus (HCMV is the major viral cause of congenital infection and birth defects. Primary maternal infection often results in virus transmission, and symptomatic babies can have permanent neurological deficiencies and deafness. Congenital infection can also lead to intrauterine growth restriction, a defect in placental transport. HCMV replicates in primary cytotrophoblasts (CTBs, the specialized cells of the placenta, and inhibits differentiation/invasion. Human trophoblast progenitor cells (TBPCs give rise to the mature cell types of the chorionic villi, CTBs and multi-nucleated syncytiotrophoblasts (STBs. Here we report that TBPCs are fully permissive for pathogenic and attenuated HCMV strains. Studies with a mutant virus lacking a functional pentamer complex (gH/gL/pUL128-131A showed that virion entry into TBPCs is independent of the pentamer. In addition, infection is blocked by a potent human neutralizing monoclonal antibody (mAb, TRL345, reactive with glycoprotein B (gB, but not mAbs to the pentamer proteins pUL130/pUL131A. Functional studies revealed that neutralization of infection preserved the capacity of TBPCs to differentiate and assemble into trophospheres composed of CTBs and STBs in vitro. Our results indicate that mAbs to gB protect trophoblast progenitors of the placenta and could be included in antibody treatments developed to suppress congenital infection and prevent disease.

  6. Formalin-inactivated EV71 vaccine candidate induced cross-neutralizing antibody against subgenotypes B1, B4, B5 and C4A in adult volunteers.

    Directory of Open Access Journals (Sweden)

    Ai-Hsiang Chou

    Full Text Available Enterovirus 71 (EV71 has caused several epidemics of hand, foot and mouth diseases (HFMD in Asia. No effective EV71 vaccine is available. A randomized and open-label phase I clinical study registered with ClinicalTrials.gov #NCT01268787, aims to evaluate the safety, reactogenicity and immunogenicity of a formalin-inactivated EV71 vaccine candidate (EV71vac at 5- and 10-µg doses. In this study we report the cross-neutralizing antibody responses from each volunteer against different subgenotypes of EV71 and CVA16.Sixty eligible healthy adults were recruited and vaccinated. Blood samples were obtained on day 0, 21 and 42 and tested against B1, B4, B5, C2, C4A, C4B and CVA16 for cross-neutralizing antibody responses.The immunogenicity of both 5- and 10- µg doses were found to be very similar. Approximately 45% of the participants had 4-fold increase in Nt, but there was no further increase in Nt after the second dose. EV71vac induced very strong cross-neutralizing antibody responses in >85% of volunteers without pre-existing Nt against subgenotype B1, B5 and C4A. EV71vac elicited weak cross-neutralizing antibody responses (∼20% of participants against a C4B and Coxsackie virus A16. Over 90% of vaccinated volunteers did not develop cross-neutralizing antibody responses (Nt<8 against a C2 strain. EV71vac can boost and significantly enhance the neutralizing antibody responses in volunteers who already had pre-vaccination antibodies against EV71 and/or CVA16.EV71vac is efficient in eliciting cross-neutralizing antibody responses against EV71 subgenotypes B1, B4, B5, and C4A, and provides the rationale for its evaluation in phase II clinical trials.ClinicalTrials.gov NCT01268787.

  7. Human sperm sex chromosome disomy and sperm DNA damage assessed by the neutral comet assay.

    Science.gov (United States)

    McAuliffe, M E; Williams, P L; Korrick, S A; Dadd, R; Marchetti, F; Martenies, S E; Perry, M J

    2014-10-10

    Is there an association between human sperm sex chromosome disomy and sperm DNA damage? An increase in human sperm XY disomy was associated with higher comet extent; however, there was no other consistent association of sex chromosome disomies with DNA damage. There is limited published research on the association between sex chromosome disomy and sperm DNA damage and the findings are not consistent across studies. We conducted a cross-sectional study of 190 men (25% ever smoker, 75% never smoker) from subfertile couples presenting at the Massachusetts General Hospital Fertility Clinic from January 2000 to May 2003. Multiprobe fluorescence in situ hybridization for chromosomes X, Y and 18 was used to determine XX, YY, XY and total sex chromosome disomy in sperm nuclei using an automated scoring method. The neutral comet assay was used to measure sperm DNA damage, as reflected by comet extent, percentage DNA in the comet tail, and tail distributed moment. Univariate and multiple linear regression models were constructed with sex chromosome disomy (separate models for each of the four disomic conditions) as the independent variable, and DNA damage parameters (separate models for each measure of DNA damage) as the dependent variable. Men with current or past smoking history had significantly greater comet extent (µm: regression coefficients with 95% CI) [XX18: 15.17 (1.98, 28.36); YY18: 14.68 (1.50, 27.86); XY18: 15.41 (2.37, 28.45); Total Sex Chromosome Disomy: 15.23 (2.09, 28.38)], and tail distributed moment [XX18: 3.01 (0.30, 5.72); YY18: 2.95 (0.24, 5.67); XY18: 3.04 (0.36, 5.72); Total Sex Chromosome Disomy: 3.10 (0.31, 5.71)] than men who had never smoked. In regression models adjusted for age and smoking, there was a positive association between XY disomy and comet extent. For an increase in XY disomy from 0.56 to 1.47% (representing the 25th to 75th percentile), there was a mean increase of 5.08 µm in comet extent. No other statistically significant

  8. Novel adenoviral vector induces T-cell responses despite anti-adenoviral neutralizing antibodies in colorectal cancer patients.

    Science.gov (United States)

    Morse, Michael A; Chaudhry, Arvind; Gabitzsch, Elizabeth S; Hobeika, Amy C; Osada, Takuya; Clay, Timothy M; Amalfitano, Andrea; Burnett, Bruce K; Devi, Gayathri R; Hsu, David S; Xu, Younong; Balcaitis, Stephanie; Dua, Rajesh; Nguyen, Susan; Balint, Joseph P; Jones, Frank R; Lyerly, H Kim

    2013-08-01

    First-generation, E1-deleted adenovirus subtype 5 (Ad5)-based vectors, although promising platforms for use as cancer vaccines, are impeded in activity by naturally occurring or induced Ad-specific neutralizing antibodies. Ad5-based vectors with deletions of the E1 and the E2b regions (Ad5 [E1-, E2b-]), the latter encoding the DNA polymerase and the pre-terminal protein, by virtue of diminished late phase viral protein expression, were hypothesized to avoid immunological clearance and induce more potent immune responses against the encoded tumor antigen transgene in Ad-immune hosts. Indeed, multiple homologous immunizations with Ad5 [E1-, E2b-]-CEA(6D), encoding the tumor antigen carcinoembryonic antigen (CEA), induced CEA-specific cell-mediated immune (CMI) responses with antitumor activity in mice despite the presence of preexisting or induced Ad5-neutralizing antibody. In the present phase I/II study, cohorts of patients with advanced colorectal cancer were immunized with escalating doses of Ad5 [E1-, E2b-]-CEA(6D). CEA-specific CMI responses were observed despite the presence of preexisting Ad5 immunity in a majority (61.3 %) of patients. Importantly, there was minimal toxicity, and overall patient survival (48 % at 12 months) was similar regardless of preexisting Ad5 neutralizing antibody titers. The results demonstrate that, in cancer patients, the novel Ad5 [E1-, E2b-] gene delivery platform generates significant CMI responses to the tumor antigen CEA in the setting of both naturally acquired and immunization-induced Ad5-specific immunity.

  9. Phytochrome quantitation in crude extracts of Avena by enzyme-linked immunosorbent assay with monoclonal antibodies

    Energy Technology Data Exchange (ETDEWEB)

    Shimazaki, Y; Cordonnier, M M; Pratt, L H

    1983-01-01

    An enzyme-linked immunosorbent assay (ELISA), which uses both rabbit polyclonal and mouse monoclonal antibodies to phytochrome, has been adapted for quantitation of phytochrome in crude plant extracts. The assay has a detection limit of about 100 pg phytochrome and can be completed within 10 h. Quantitation of phytochrome in crude extracts of etiolated oat seedlings by ELISA gave values that agreed well with those obtained by spectrophotometric assay. When etiolated oat seedlings were irradiated continuously for 24 h, the amount of phytochrome detected by ELISA and by spectrophotometric assay decreased by more than 1000-fold and about 100-fold, respectively. This discrepancy indicates that phytochrome in light-treated plants may be antigenically distinct from that found in fully etiolated plants. When these light-grown oat seedlings were kept in darkness for 48 h, phytochrome content detected by ELISA increased by 50-fold in crude extracts of green oat shoots, but only about 12-fold in extracts of herbicide-treated oat shoots. Phytochrome reaccumulation in green oat shoots was initially more rapid in the more mature cells of the primary leaf tip than near the basal part of the shoot. The inhibitory effect of Norflurazon on phytochrome accumulation was much more evident near the leaf tip than the shoot base. A 5-min red irradiation of oat seedlings at the end of a 48-h dark period resulted in a subsequent, massive decrease in phytochrome content in crude extracts from both green and Norflurazon-bleached oat shoots. These observations eliminate the possibility that substantial accumulation of chromophore-free phytochrome was being detected and indicate that Norflurazon has a substantial effect on phytochrome accumulation during a prolonged dark period. 25 references, 9 figures, 3 tables.

  10. Structural Basis for the Binding of the Neutralizing Antibody, 7D11, to the Poxvirus L1 Protein

    Science.gov (United States)

    2007-08-01

    pCR- 7D11-vHC and pCR-7D11- vLC , respectively. Crystallization of the complex between L1 and 7D11-Fab VACV L1 protein was expressed and purified as...2005. Vaccinia virus H3L envelope protein is a major target of neutralizing antibodies in humans and elicits protection against lethal challenge in...D.M., Schmaljohn, C., Schmaljohn, A., 2000. DNA vaccination with vaccinia virus L1R and A33R genes protects mice against a lethal poxvirus challenge

  11. A novel TNFα antagonizing peptide-Fc fusion protein designed based on CDRs of TNFα neutralizing monoclonal antibody

    International Nuclear Information System (INIS)

    Qin Weisong; Feng Jiannan; Zhang Wei; Li Yan; Shen, Beifen

    2004-01-01

    The variable regions of antibody molecules bind antigens with high affinity and specificity. The binding sites are imparted largely to the hypervariable portions (i.e., CDRs) of the variable region. Peptides derived from CDRs can bind antigen with similar specificity acting as mimic of antibody and become drug-designing core, although with markedly lower affinity. In order to increase the affinity and bioactivity, in this study, a novel peptide (PT) designed on CDRs of a TNFα neutralizing monoclonal antibody Z12 was linked with Fc fragment of human IgG1. The interaction mode of PT-linker-Fc (PLF) with TNFα was analyzed with computer-guided molecular modeling method. After expression in Escherichia coli and purification, recombinant PT-linker-Fc could bind directly with the TNFα coated on the ELISA plates. Furthermore, PLF could competitively inhibit the binding of Z12 to TNFα and also inhibit the TNFα-induced cytotoxicity on L929 cells. The TNFα antagonizing activity of PLF was significantly higher than that of the free peptide. This study highlights the potential of human Fc to enhance the potency of peptides designed on the CDRs of antibodies and could be useful in developing new TNFα antagonists

  12. Enzyme linked immunosorbent assay for detecting antibody to Trichomonas vaginalis: use of whole cells and aqueous extract as antigen.

    OpenAIRE

    Alderete, J F

    1984-01-01

    An enzyme linked immunosorbent assay (ELISA) for detecting antibody to antigenic Trichomonas vaginalis macromolecules has been identified using whole cells or an aqueous protein extract as antigen. The test was developed under optimum conditions using serum samples from experimental animals. The sensitivity of the ELISA was equal to or greater than that obtained by radioimmunoprecipitation and electrophoresis-fluorography techniques. The ELISA was capable of assessing antibody responses durin...

  13. Differentiation of ruminal bacterial species by enzyme-linked immunosorbent assay using egg yolk antibodies from immunized chicken hens.

    OpenAIRE

    Ricke, S C; Schaefer, D M; Cook, M E; Kang, K H

    1988-01-01

    Cross-reactivity among four species of ruminal bacteria was examined by using egg yolk antibodies from immunized Leghorn laying hens and an enzyme-linked-immunosorbent assay. The effects of the four species on the hens were compared on various days postimmunization. Hens injected with the same bacterial species had similar apparent antibody levels over the entire postimmunization period, but only Bacteroides ruminicola B1(4) and Selenomonas ruminantium D antigens elicited early increases in a...

  14. Identification of a Vesicular-Arbuscular Mycorrhizal Fungus by Using Monoclonal Antibodies in an Enzyme-Linked Immunosorbent Assay

    OpenAIRE

    Wright, Sara F.; Morton, Joseph B.; Sworobuk, Janis E.

    1987-01-01

    Spore morphology is currently used to identify species of vesicular-arbuscular mycorrhizal fungi. We report the first use of a highly specific immunological method for identification of a vesicular-arbuscular mycorrhizal fungus. Two monoclonal antibodies were produced against Glomus occultum. Monoclonal antibodies reacted strongly with both spores and hyphae in an indirect enzyme-linked immunosorbent assay. All other mycorrhizal (29 species) and nonmycorrhizal (5 species) fungi tested were no...

  15. Improvement of an enzyme immunosorbent assay for detecting antibodies against Dioctophyma renale.

    Science.gov (United States)

    Pedrassani, Daniela; do Nascimento, Adjair Antonio; André, Marcos Rogério; Machado, Rosangela Zacarias

    2015-09-15

    An available enzyme-linked immunosorbent assay (ELISA) was studied for the detection of anti-Dioctophyma renale antibodies in the sera of dogs using, detection of parasite eggs in urine sediment as a reference test. ELISA uses a soluble antigenic preparation of esophagus of D. renale and the optimal dilutions of the antigen, serum and conjugate were determined by means of checker board titration, using positive (n=13) and negative (n=27) reference serum. The specificity and sensitivity of the ELISA were 93.8% and 92.3% respectively and the kappa index was good (0.76). These results suggest that ELISA described may prove to be an effective serological test for detecting dogs infected and exposed to this parasite mainly dogs that are not eliminating parasite eggs through their urine. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. A radioisotope dilution assay for unlabelled vitamin B12-intrinsic factor complex employing the binding intrinsic factor antibody: probable evidence for two types of binding antibody

    International Nuclear Information System (INIS)

    Jacob, E.; O'Brien, H.A.W.; Mollin, D.L.

    1977-01-01

    A new radioisotope dilution assay for vitamin B 12 -intrinsic factor complex is described. The method is based on the use of the binding type intrinsic antibody (the binding reagent), which when combined with the intrinsic factor-vitamin B 12 complex (labelled ligand), is quantitatively adsorbed onto zirconium phosphate gel pH 6.25. The new assay has been shown to provide a measure of intrinsic factor comparable with other intrinsic factor assays, but it has the important advantage of being able to measure the unlabelled vitamin B 12 -intrinsic factor complex (unlabelled ligand), and will, therefore, be valuable in the study of physiological events in the gastrointestinal tract. During the study, it was found that there is some evidence for at least two types of binding intrinsic factor antibody: One which combines preferentially with the intrinsic factor-vitamin B 12 complex and one which combines equally well with this complex or with free intrinsic factor. (author)

  17. Sero-prevalence of virus neutralizing antibodies for rabies in different groups of dogs following vaccination.

    Science.gov (United States)

    Pimburage, R M S; Gunatilake, M; Wimalaratne, O; Balasuriya, A; Perera, K A D N

    2017-05-18

    Mass vaccination of dogs is considered fundamental for national rabies control programmes in Sri Lanka, as dog is the main reservoir and transmitter of the disease. Dogs were followed to determine the sero-prevalence of antibodies to the rabies virus. Altogether 510 previously vaccinated and unvaccinated dogs with owners (domestic dogs) and dogs without owners (stray dogs) of the local guard dog breed in different age groups recruited from Kalutara District, Sri Lanka. The dogs were vaccinated with a monovalent inactivated vaccine intramuscularly and serum antibody titres on days 0, 30, 180 and 360 were determined by the Rapid Fluorescent Focus Inhibition Test (RFFIT). The results indicated, a single dose of anti-rabies vaccination fails to generate a protective level of immunity (0.5 IU/ml) which lasts until 1 year in 40.42% of dogs without owners and 57.14% of previously unvaccinated juvenile (age: 3 months to 1 year) dogs with owners. More than one vaccination would help to maintain antibody titres above the protective level in the majority of dogs. The pattern of antibody titre development in annually vaccinated and irregularly vaccinated (not annual) adult dogs with owners is closely similar irrespective of regularity in vaccination. Previously vaccinated animals have higher (2 IU/ml) antibody titres to begin with and have a higher antibody titre on day 360 too. They show a very good antibody titre by day 180. Unvaccinated animals start with low antibody titre and return to low titres by day 360, but have a satisfactory antibody titre by day 180. A single dose of anti-rabies vaccination is not sufficient for the maintenance of antibody titres for a period of 1 year in puppies, juvenile dogs with owners and in dogs without owners. Maternal antibodies do not provide adequate protection to puppies of previously vaccinated dams and puppies of previously unvaccinated dams. Immunity development after vaccination seems to be closely similar in both the groups

  18. Evaluation of the Antibody in Lymphocyte Supernatant Assay to Detect Active Tuberculosis.

    Directory of Open Access Journals (Sweden)

    Margaretha Sariko

    Full Text Available We aimed to evaluate the antibody in lymphocyte supernatant (ALS assay as a biomarker to diagnose tuberculosis among adults from Tanzania with and without HIV.Adults admitted with suspicion for tuberculosis had sputa obtained for GeneXpert MTB/RIF, acid-fast bacilli smear and mycobacterial culture; blood was obtained prior to treatment initiation and after 4 weeks. Adults hospitalized with non-infectious conditions served as controls. Peripheral blood mononuclear cells were cultured unstimulated for 72 hours. Anti-mycobacterial antibodies were measured from culture supernatants by ELISA, using BCG vaccine as the coating antigen. Median ALS responses were compared between cases and controls at baseline and between cases over time.Of 97 TB cases, 85 were microbiologically confirmed and 12 were clinically diagnosed. Median ALS responses from TB cases (0.366 OD from confirmed cases and 0.285 from clinical cases were higher compared to controls (0.085, p<0.001. ALS responses did not differ based on HIV status, CD4 count or sputum smear status. Over time, the median ALS values declined significantly (0.357 at baseline; 0.198 after 4-weeks, p<0.001.Robust ALS responses were mounted by patients with TB regardless of HIV status, CD4 count, or low sputum bacillary burden, potentially conferring a unique niche for this immunologic biomarker for TB.

  19. [Virus strain specific serum neutralizing antibodies in children and adolescents immunized with a Russian mumps vaccine].

    Science.gov (United States)

    Otrashevskaia, E V; Krasil'nikov, I V; Ignat'ev, G M

    2010-01-01

    Postvaccination immunity was studied in the children and teenagers without a history of clinical mumps infection, who had been immunized with the Leningrad-3 mumps vaccine. The level of specific lgG in ELISA and that and spectrum of their neutralizing activity against a vaccine strain and three heterologous mumps virus (MV) strains (genotypes A, C, and H) were measured. The investigation included 151 sera from the vaccinees aged 3 to 17 years, possessing the detectable specific IgG titers in ELISA and the detectable neutralizing titers against the vaccine strain. 97.4% of the vaccinees had neutralizing activity against 1-3 heterologous MV strains. A preponderance of neutralizing titers against heterologous MV strains by 1-log2 in some sera (6.5-32.5 depending on age) was most likely to suggest that the vaccinees' had been in contact with these virus strains in the past. In our investigation, a combination of positive IgG titers and neutralizing titers against the vaccine strain 2-log2 or higher provided the protection of the vaccinated children and teenagers against the symptomatic infection. There was a pronounced buster effect of the second immunization and a drop in the neutralizing activity of the sera from the vaccinated children and adolescents over time after the first and second immunization.

  20. Development of microLIPS (Luciferase Immunoprecipitation Systems): a novel microfluidic assay for rapid serum antibody detection

    Science.gov (United States)

    Chandrangsu, Matt; Burbelo, Peter D.; Iadarola, Michael J.; Smith, Paul D.; Morgan, Nicole Y.

    2012-06-01

    There is considerable interest in the development of rapid, point-of-care antibody detection for the diagnosis of infectious and auto-immune diseases. In this paper, we present work on the development of a self-contained microfluidic format for the Luciferase Immunoprecipitation Systems (LIPS) assay. Whereas the majority of immunoassays for antigen-specific antibodies employ either bacteria- or yeast-expressed proteins and require the use of secondary antibodies, the LIPS technique uses a fusion protein comprised of a Renilla luciferase reporter and the antigen of interest produced via mammalian cell culture, ensuring the addition of mammalian post-translational modifications. Patient serum is mixed with the fusion protein and passed over immobilized Protein A/G; after washing, the only remaining luciferase-tagged antigens are those retained by specific antibodies. These can be quantitatively measured using chemiluminescence upon the introduction of coelenterazine. The assay has been successfully employed for a wide variety of diseases in a microwell format. We report on a recent demonstration of rapid HSV-2 diagnosis with the LIPS assay in a microfluidic format, using one microliter of serum and obtaining results in under ten minutes. We will also discuss recent progress on two fronts, both aimed at the deployment of this technology in the field: first, simplifying assay operation through the automation of flow control using power-free means; and second, efforts to increase signal levels, primarily through strategies to increase antibody binding capacity, in order to move towards portable battery powered electronics.

  1. Sequential immunization with V3 peptides from primary human immunodeficiency virus type 1 produces cross-neutralizing antibodies against primary isolates with a matching narrow-neutralization sequence motif.

    Science.gov (United States)

    Eda, Yasuyuki; Takizawa, Mari; Murakami, Toshio; Maeda, Hiroaki; Kimachi, Kazuhiko; Yonemura, Hiroshi; Koyanagi, Satoshi; Shiosaki, Kouichi; Higuchi, Hirofumi; Makizumi, Keiichi; Nakashima, Toshihiro; Osatomi, Kiyoshi; Tokiyoshi, Sachio; Matsushita, Shuzo; Yamamoto, Naoki; Honda, Mitsuo

    2006-06-01

    An antibody response capable of neutralizing not only homologous but also heterologous forms of the CXCR4-tropic human immunodeficiency virus type 1 (HIV-1) MNp and CCR5-tropic primary isolate HIV-1 JR-CSF was achieved through sequential immunization with a combination of synthetic peptides representing HIV-1 Env V3 sequences from field and laboratory HIV-1 clade B isolates. In contrast, repeated immunization with a single V3 peptide generated antibodies that neutralized only type-specific laboratory-adapted homologous viruses. To determine whether the cross-neutralization response could be attributed to a cross-reactive antibody in the immunized animals, we isolated a monoclonal antibody, C25, which neutralized the heterologous primary viruses of HIV-1 clade B. Furthermore, we generated a humanized monoclonal antibody, KD-247, by transferring the genes of the complementary determining region of C25 into genes of the human V region of the antibody. KD-247 bound with high affinity to the "PGR" motif within the HIV-1 Env V3 tip region, and, among the established reference antibodies, it most effectively neutralized primary HIV-1 field isolates possessing the matching neutralization sequence motif, suggesting its promise for clinical applications involving passive immunizations. These results demonstrate that sequential immunization with B-cell epitope peptides may contribute to a humoral immune-based HIV vaccine strategy. Indeed, they help lay the groundwork for the development of HIV-1 vaccine strategies that use sequential immunization with biologically relevant peptides to overcome difficulties associated with otherwise poorly immunogenic epitopes.

  2. The HIV-1 V3 domain on field isolates: participation in generation of escape virus in vivo and accessibility to neutralizing antibodies

    DEFF Research Database (Denmark)

    Arendrup, M; Akerblom, L; Heegaard, P M

    1995-01-01

    The V3 domain is highly variable and induces HIV neutralizing antibodies (NA). Here we addressed the issues of 1) the participation of mutations in V3 in generation of neutralization resistant escape virus in vivo and 2) the applicability of synthetic V3 peptides corresponding to field isolates...... to induce neutralizing immune sera. Seven peptides corresponding to the V3 region of primary and escape virus from 3 HIV-1 infected patients were synthesized and used for antibody (Abs) studies and immunizations. The anti-V3 Abs titre in patient serum was generally low against peptides corresponding...... to autologous virus isolated later than the serum sample in contrast to the titre against peptides corresponding to virus isolated earlier than the serum sample. Furthermore, neutralizing anti-V3 monoclonal antibodies (MAbs) raised against V3 peptides from laboratory strains of HIV-1 showed distinct binding...

  3. Evaluation of the Chagas Stat-Paktm Assay for Detection of Trypanosoma cruzi Antibodies in Wildlife Reservoirs

    Science.gov (United States)

    Yabsley, Michael J.; Brown, Emily L.; Roellig, Dawn M.

    2010-01-01

    An immunochromatographic assay (Chagas Stat-Pak™) was evaluated for the detection of Trypanosoma cruzi antibodies in 4 species of wildlife reservoirs. Antibodies to T. cruzi were detected in raccoons (Procyon lotor) (naturally and experimentally infected) and degus (Octodon degu) (experimentally-infected) using the Chagas Stat-Pak. In naturally exposed wild raccoons, the Chagas Stat-Pak had a sensitivity and specificity of 66.7–80.0% and 96.3%, respectively. Compared with indirect immunofluorescent antibody assay results, serocon-version as determined by Chagas Stat-Pak was delayed for experimentally infected raccoons, but occurred sooner in experimentally infected degus. The Chagas Stat-Pak did not detect antibodies in naturally or experimentally infected Virginia opossums (Didelphis virginiana) or in experimentally infected short-tailed opossums (Monodelphis domestica). These data suggest that the Chagas Stat-Pak might be useful in field studies of raccoons and degus when samples would not be available for more-conventional serologic assays. Because this assay did not work on either species of marsupial, the applicability of the assay should be examined before it is used in other wild species. PMID:19016578

  4. Two-site sandwich immunoradiometric assay of human lymphotoxin with monoclonal antibodies and its applications

    Energy Technology Data Exchange (ETDEWEB)

    Meager, A; Parti, S; Leung, H; Woolley, J; Peil, E; Sidhu, S; Roberts, T

    1987-11-23

    Three monoclonal antibodies (MoAbs L49-15, L81-11 and L238-14) were raised against recombinant human lymphotoxin (rLT) derived from E. coli containing the cDNA sequence specifying LT. These MoAbs were ideal reagents for immunoassay of LT and a very sensitive, highly specific immunoradiometric assay (IRMA) was developed. This assay was rapid to perform and was capable of detecting as little as 10 pg/ml of LT. Application of the LT IRMA in combination with previously developed human gamma-interferon (IFN-..gamma..) and human tumour necrosis factor (TNF)-specific IRMA permitted independent estimations of these three substances to be carried out in parallel. By these means, it was found that RPMI 1788 lymphoblastoid cell line produced both LT and TNF, but not IFN-..gamma... Extensive analyses on cytokine (monokine and lymphokine) preparations derived from a variety of activated lymphocytes are also reported. Co-production of LT, TNF, and IFN-..gamma.. was a common finding, even occurring in alloantigen-specific T helper cell clones. 45 refs.; 3 figs.; 4 tabs.

  5. Human Papillomavirus neutralizing and cross-reactive antibodies induced in HIV-positive subjects after vaccination with quadrivalent and bivalent HPV vaccines

    DEFF Research Database (Denmark)

    Faust, Helena; Nielsen, Lars Toft; Sehr, Peter

    2016-01-01

    Ninety-one HIV-infected individuals (61 men and 30 women) were randomized to vaccination either with quadrivalent (Gardasil™) or bivalent (Cervarix™) HPV vaccine. Neutralizing and specific HPV-binding serum antibodies were measured at baseline and 12 months after the first vaccine dose. Presence...... of neutralizing and binding antibodies had good agreement (average Kappa for HPV types 6, 11, 16, 18, 31, 33 and 45 was 0.65). At baseline, 88% of subjects had antibodies against at least one genital HPV. Following vaccination with Cervarix™, all subjects became seropositive for HPV16 and 18. After Gardasil......™ vaccination, 96% of subjects seroconverted for HPV16 and 73% for HPV18. Levels of HPV16-specific antibodies were 10IU in 85% of study subjects after vaccination. Antibodies against non-vaccine HPV types appeared after Gardasil...

  6. Crystal structure of the Hendra virus attachment G glycoprotein bound to a potent cross-reactive neutralizing human monoclonal antibody.

    Directory of Open Access Journals (Sweden)

    Kai Xu

    Full Text Available The henipaviruses, represented by Hendra (HeV and Nipah (NiV viruses are highly pathogenic zoonotic paramyxoviruses with uniquely broad host tropisms responsible for repeated outbreaks in Australia, Southeast Asia, India and Bangladesh. The high morbidity and mortality rates associated with infection and lack of licensed antiviral therapies make the henipaviruses a potential biological threat to humans and livestock. Henipavirus entry is initiated by the attachment of the G envelope glycoprotein to host cell membrane receptors. Previously, henipavirus-neutralizing human monoclonal antibodies (hmAb have been isolated using the HeV-G glycoprotein and a human naïve antibody library. One cross-reactive and receptor-blocking hmAb (m102.4 was recently demonstrated to be an effective post-exposure therapy in two animal models of NiV and HeV infection, has been used in several people on a compassionate use basis, and is currently in development for use in humans. Here, we report the crystal structure of the complex of HeV-G with m102.3, an m102.4 derivative, and describe NiV and HeV escape mutants. This structure provides detailed insight into the mechanism of HeV and NiV neutralization by m102.4, and serves as a blueprint for further optimization of m102.4 as a therapeutic agent and for the development of entry inhibitors and vaccines.

  7. Evaluation of the Potency, Neutralizing Antibody Response, and Stability of a Recombinant Fusion Protein Vaccine for Streptococcus pyogenes.

    Science.gov (United States)

    Burlet, E; HogenEsch, H; Dunham, A; Morefield, G

    2017-05-01

    Streptococcus pyogenes or group A streptococcus (GAS) is a Gram-positive bacterium that can cause a wide range of diseases, including pharyngitis, impetigo, scarlet fever, necrotizing fasciitis, rheumatic fever, and streptococcal toxic shock syndrome. Despite the increasing burden on global health caused by GAS, there is currently no licensed vaccine available. In this study, we evaluated immunogenicity, induction of neutralizing antibodies, and stability of a new recombinant fusion protein vaccine that targets infections from GAS. The recombinant fusion protein (SpeAB) combines inactive mutant forms of streptococcal pyrogenic exotoxin A (SpeA) and streptococcal pyrogenic exotoxin B (SpeB). The SpeAB vaccine evaluated in this study was adsorbed to an aluminum adjuvant and demonstrated robust immunogenicity, eliciting production of specific neutralizing antibodies against SpeA and SpeB, two major virulence factors of S. pyogenes. Stability studies suggest that the vaccine will retain immunogenicity for at least 2 years when stored at refrigerated temperatures. This novel vaccine shows great potential to provide protection against GAS infections and to reduce the burden of GAS disease globally.

  8. Labelled antibody assays for measuring free triiodothyronine: evaluation and comparison with a labelled analog method

    International Nuclear Information System (INIS)

    Sapin, R.; Gasser, F.; Schlienger, J.L.; Chambron, J.

    1993-01-01

    We evaluated analytically and clinically two new one-step labelled antibody assays for measuring free triiodothyronine (FT3): the first, radiolabelled with 125 I, Amerlex-MAB (MAB) from Kodak diagnostic, and the second, labelled with peroxidase, Enzymum-test FT3 (BM) from Boehringer Mannheim adapted for the Boehringer ES 600 analyzer. The clinical results were compared with those obtained with a radiolabelled analog tracer kit, Amerlex-M (M) from Kodak diagnostic. The latter kit is known to give low FT3 results in sera with low albumin concentrations. Analytical performances of the automated method (BM) were better than those obtained with the manual method (MAB): intra-assay reproducibility (CV<3% vs CV about 5%), inter-assay reproducibility (CV<4% vs CV between 4 and 8%) and mean drift (+1.25% vs -4.3%). The detection limit was low for both kits (<1 pmol/l). In the euthyroid reference group (n = 98) we observed a significant difference between outpatient and hospitalized patient FT3 concentrations as measured with the M kit only. Clinical sensitivity for hyperthyroidism (n = 38) was better for the MAB (92%) than for the BM kit (76%). Specificity in euthyroid L-thyroxine (T4) treated patients (n = 26) was good for both kits (MAB: 92%; BM: 88%) . Hypoalbuminemia (n = 8) decreased FT3 results as follows: M, very significantly; BM, significantly; MAB, only slightly. In patients treated with amiodarone (n = 5), a drug known to lower the metabolic conversion of T4 to T3, the increase of the MAB FT3 results contrasted with the decrease of the BM and M results. In conclusion, results of the two new kits were not strongly influenced by hypoalbuminemia. The MAB results showing lack of decrease in patients with non-thyroidal illness without hypoalbuminemia and in amiodarone-treated patients were unexpected

  9. 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

  10. Development of Two Antibody Detection Enzyme-Linked Immunosorbent Assays for Serodiagnosis of Human Chronic Fascioliasis

    Science.gov (United States)

    Cabán-Hernández, Kimberly; Gaudier, José F.; Ruiz-Jiménez, Caleb

    2014-01-01

    Coprological examination based on egg detection in stool samples is currently used as the gold standard for the diagnosis of human fascioliasis. However, this method is not effective during the acute phase of the disease and has poor sensitivity during the chronic phase. Serodiagnosis has become an excellent alternative to coprological examination in efforts to combat the effects of fascioliasis on human and animal health. Two novel recombinant Fasciola hepatica proteins, i.e., a ferritin (FhFtn-1) and a tegument-associated protein (FhTP16.5), were used as antigens to develop in-house enzyme-linked immunosorbent assay (ELISA) methods. The assays were optimized and validated using 152 serum samples from humans with a known infection status, including healthy subjects, patients with chronic fascioliasis, and patients with other parasitic diseases. The FhFtn-1 ELISA was shown to be 96.6% sensitive and 95.7% specific; the respective parameters for the FhTP16.5 ELISA were 91.4% and 92.4%. The performances of the FhFtn-1 and FhTP16.5 ELISAs were compared with that of an available commercial test (the DRG test) using a subset of serum samples. Our in-house tests were slightly more sensitive than the DRG test in detecting antibodies against F. hepatica, but the differences were not statistically significant. In conclusion, the present study provides evidence for the potential of the FhFtn-1 and FhTP16.5 ELISAs as diagnostic tools for human fascioliasis, as might be implemented in conjunction with standard assays for large-scale screenings in areas where the disease is endemic and for the detection of occasional cases in clinical laboratories. PMID:24353000

  11. Development of two antibody detection enzyme-linked immunosorbent assays for serodiagnosis of human chronic fascioliasis.

    Science.gov (United States)

    Cabán-Hernández, Kimberly; Gaudier, José F; Ruiz-Jiménez, Caleb; Espino, Ana M

    2014-03-01

    Coprological examination based on egg detection in stool samples is currently used as the gold standard for the diagnosis of human fascioliasis. However, this method is not effective during the acute phase of the disease and has poor sensitivity during the chronic phase. Serodiagnosis has become an excellent alternative to coprological examination in efforts to combat the effects of fascioliasis on human and animal health. Two novel recombinant Fasciola hepatica proteins, i.e., a ferritin (FhFtn-1) and a tegument-associated protein (FhTP16.5), were used as antigens to develop in-house enzyme-linked immunosorbent assay (ELISA) methods. The assays were optimized and validated using 152 serum samples from humans with a known infection status, including healthy subjects, patients with chronic fascioliasis, and patients with other parasitic diseases. The FhFtn-1 ELISA was shown to be 96.6% sensitive and 95.7% specific; the respective parameters for the FhTP16.5 ELISA were 91.4% and 92.4%. The performances of the FhFtn-1 and FhTP16.5 ELISAs were compared with that of an available commercial test (the DRG test) using a subset of serum samples. Our in-house tests were slightly more sensitive than the DRG test in detecting antibodies against F. hepatica, but the differences were not statistically significant. In conclusion, the present study provides evidence for the potential of the FhFtn-1 and FhTP16.5 ELISAs as diagnostic tools for human fascioliasis, as might be implemented in conjunction with standard assays for large-scale screenings in areas where the disease is endemic and for the detection of occasional cases in clinical laboratories.

  12. Measles Virus Neutralizing Antibodies in Intravenous Immunoglobulins: Is an Increase by Revaccination of Plasma Donors Possible?

    Science.gov (United States)

    Modrof, Jens; Tille, Björn; Farcet, Maria R; McVey, John; Schreiner, Jessica A; Borders, Charles M; Gudino, Maria; Fitzgerald, Peter; Simon, Toby L; Kreil, Thomas R

    2017-11-15

    We report a screen of plasma donors confirming that widespread use of childhood measles vaccination since 1963 resulted in a decrease in average measles virus antibody titers among plasma donors, which is reflected in intravenous immunoglobulins (IVIGs). The measles virus antibody titer, however, is a potency requirement for IVIGs, as defined in a Food and Drug Administration regulation. To mitigate the decline in measles virus antibody titers in IVIGs and to ensure consistent product release, revaccination of plasma donors was investigated as a means to boost titers. However, revaccination-induced titer increases were only about 2-fold and short-lived. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.

  13. Atypical and classical memory B cells produce Plasmodium falciparum neutralizing antibodies

    DEFF Research Database (Denmark)

    Muellenbeck, Matthias F; Ueberheide, Beatrix; Amulic, Borko

    2013-01-01

    signs of active antibody secretion. AtM and CM were also different in their IgG gene repertoire, suggesting that they develop from different precursors. The findings provide direct evidence that natural Pf infection leads to the development of protective memory B cell antibody responses and suggest......Antibodies can protect from Plasmodium falciparum (Pf) infection and clinical malaria disease. However, in the absence of constant reexposure, serum immunoglobulin (Ig) levels rapidly decline and full protection from clinical symptoms is lost, suggesting that B cell memory is functionally impaired...... that constant immune activation rather than impaired memory function leads to the accumulation of AtM in malaria. Understanding the memory B cell response to natural Pf infection may be key to the development of a malaria vaccine that induces long-lived protection....

  14. 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

  15. Monoclonal Antibodies Follow Distinct Aggregation Pathways During Production-Relevant Acidic Incubation and Neutralization

    DEFF Research Database (Denmark)

    Pedersen, Thomas Skamris; Tian, Xinsheng; Thorolfsson, Matthias

    2016-01-01

    and orthogonal analytical methods, including small-angle X-ray scattering and dynamic light scattering and supplemented the experimental data with crystal structure-based spatial aggregation propensity (SAP) calculations. RESULTS: We revealed distinct solution behaviors between the three mAb models: At acidic p......PURPOSE: Aggregation aspects of therapeutic monoclonal antibodies (mAbs) are of common concern to the pharmaceutical industry. Low pH treatment is applied during affinity purification and to inactivate endogenous retroviruses, directing interest to the mechanisms of acid-induced antibody...... distinguish between reversible and irreversible mAb aggregation pathways at early stages of acidic treatment....

  16. Use of a Granulocyte Immunofluorescence Assay Designed for Humans for Detection of Antineutrophil Cytoplasmic Antibodies in Dogs with Chronic Enteropathies.

    Science.gov (United States)

    Florey, J; Viall, A; Streu, S; DiMuro, V; Riddle, A; Kirk, J; Perazzotti, L; Affeldt, K; Wagner, R; Vaden, S; Harris, T; Allenspach, K

    2017-07-01

    Perinuclear antineutrophil cytoplasmic antibodies (pANCA) previously have been shown to be serum markers in dogs with chronic enteropathies, with dogs that have food-responsive disease (FRD) having higher frequencies of seropositivity than dogs with steroid-responsive disease (SRD). The indirect immunofluorescence (IIF) assay used in previous publications is time-consuming to perform, with low interobserver agreement. We hypothesized that a commercially available granulocyte IIF assay designed for humans could be used to detect perinuclear antineutrophil cytoplasmic antibodies in dogs. Forty-four dogs with FRD, 20 dogs with SRD, 20 control dogs, and 38 soft-coated wheaten terrier (SCWT) or SCWT-cross dogs. A granulocyte assay designed for humans was used to detect pANCA, cANCA, and antinuclear antibodies (ANA), as well as antibodies against proteinase-3 protein (PR-3) and myeloperoxidase protein (MPO) in archived serum samples. Sensitivity of the granulocyte assay to predict FRD in dogs was 0.61 (95% confidence interval (CI), 0.45, 0.75), and specificity was 1.00 (95% CI, 0.91, 1.00). A significant association was identified between positive pANCA or cANCA result and diagnosis of FRD (P < 0.0001). Agreement between the two assays to detect ANCA in the same serum samples from SCWT with protein-losing enteropathy/protein-losing nephropathy (PLE/PLN) was substantial (kappa, 0.77; 95% CI, 0.53, 1.00). Eight ANCA-positive cases were positive for MPO or PR-3 antibodies. The granulocyte immunofluorescence assay used in our pilot study was easy and quick to perform. Agreement with the previously published method was good. Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

  17. The potential value of the neutral comet assay and the expression of genes associated with DNA damage in assessing the radiosensitivity of tumor cells.

    Science.gov (United States)

    Jayakumar, Sundarraj; Bhilwade, Hari N; Pandey, Badri N; Sandur, Santosh K; Chaubey, Ramesh C

    2012-10-09

    The assessment of tumor radiosensitivity would be particularly useful in optimizing the radiation dose during radiotherapy. Therefore, the degree of correlation between radiation-induced DNA damage, as measured by the alkaline and the neutral comet assays, and the clonogenic survival of different human tumor cells was studied. Further, tumor radiosensitivity was compared with the expression of genes associated with the cellular response to radiation damage. Five different human tumor cell lines were chosen and the radiosensitivity of these cells was established by clonogenic assay. Alkaline and neutral comet assays were performed in γ-irradiated cells (2-8Gy; either acute or fractionated). Quantitative PCR was performed to evaluate the expression of DNA damage response genes in control and irradiated cells. The relative radiosensitivity of the cell lines assessed by the extent of DNA damage (neutral comet assay) immediately after irradiation (4Gy or 6Gy) was in agreement with radiosensitivity pattern obtained by the clonogenic assay. The survival fraction of irradiated cells showed a better correlation with the magnitude of DNA damage measured by the neutral comet assay (r=-0.9; Pcomet assay (r=-0.73; Pcomet assay was better than alkaline comet assay for assessment of radiosensitivities of tumor cells after acute or fractionated doses of irradiation. © 2012 Elsevier B.V. All rights reserved.

  18. Targeted Delivery of Neutralizing Anti-C5 Antibody to Renal Endothelium Prevents Complement-Dependent Tissue Damage

    Directory of Open Access Journals (Sweden)

    Paolo Durigutto

    2017-09-01

    Full Text Available Complement activation is largely implicated in the pathogenesis of several clinical conditions and its therapeutic neutralization has proven effective in preventing tissue and organ damage. A problem that still needs to be solved in the therapeutic control of complement-mediated diseases is how to avoid side effects associated with chronic neutralization of the complement system, in particular, the increased risk of infections. We addressed this issue developing a strategy based on the preferential delivery of a C5 complement inhibitor to the organ involved in the pathologic process. To this end, we generated Ergidina, a neutralizing recombinant anti-C5 human antibody coupled with a cyclic-RGD peptide, with a distinctive homing property for ischemic endothelial cells and effective in controlling tissue damage in a rat model of renal ischemia/reperfusion injury (IRI. As a result of its preferential localization on renal endothelium, the molecule induced complete inhibition of complement activation at tissue level, and local protection from complement-mediated tissue damage without affecting circulating C5. The ex vivo binding of Ergidina to surgically removed kidney exposed to cold ischemia supports its therapeutic use to prevent posttransplant IRI leading to delay of graft function. Moreover, the finding that the ex vivo binding of Ergidina was not restricted to the kidney, but was also seen on ischemic heart, suggests that this RGD-targeted anti-C5 antibody may represent a useful tool to treat organs prior to transplantation. Based on this evidence, we propose preliminary data showing that Ergidina is a novel targeted drug to prevent complement activation on the endothelium of ischemic kidney.

  19. Fully human broadly neutralizing monoclonal antibodies against influenza A viruses generated from the memory B cells of a 2009 pandemic H1N1 influenza vaccine recipient

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Weibin [Molecular Virus Unit, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200025 (China); Chen, Aizhong [Key Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031 (China); Miao, Yi [Shanghai Xuhui Central Hospital, Shanghai 200031 (China); Xia, Shengli [Center for Disease Control and Prevention of Henan Province, Zhengzhou 450016 (China); Ling, Zhiyang; Xu, Ke; Wang, Tongyan [Molecular Virus Unit, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200025 (China); Xu, Ying; Cui, Jun; Wu, Hongqiang; Hu, Guiyu; Tian, Lin; Wang, Lingling [Key Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031 (China); Shu, Yuelong [Chinese Center for Disease Control and Prevention, Beijing 102206 (China); Ma, Xiaowei [Hualan Biological Bacterin Company, Xinxiang 453003 (China); Xu, Bianli; Zhang, Jin [Center for Disease Control and Prevention of Henan Province, Zhengzhou 450016 (China); Lin, Xiaojun, E-mail: linxiaojun@hualan.com [Hualan Biological Bacterin Company, Xinxiang 453003 (China); Bian, Chao, E-mail: cbian@sibs.ac.cn [Key Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031 (China); Sun, Bing, E-mail: bsun@sibs.ac.cn [Molecular Virus Unit, Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200025 (China); Key Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031 (China)

    2013-01-20

    Whether the 2009 pandemic H1N1 influenza vaccine can induce heterosubtypic cross-protective anti-hemagglutinin (HA) neutralizing antibodies is an important issue. We obtained a panel of fully human monoclonal antibodies from the memory B cells of a 2009 pandemic H1N1 influenza vaccine recipient. Most of the monoclonal antibodies targeted the HA protein but not the HA1 fragment. Among the analyzed antibodies, seven mAbs exhibited neutralizing activity against several influenza A viruses of different subtypes. The conserved linear epitope targeted by the neutralizing mAbs (FIEGGWTGMVDGWYGYHH) is part of the fusion peptide on HA2. Our work suggests that a heterosubtypic neutralizing antibody response primarily targeting the HA stem region exists in recipients of the 2009 pandemic H1N1 influenza vaccine. The HA stem region contains various conserved neutralizing epitopes with the fusion peptide as an important one. This work may aid in the design of a universal influenza A virus vaccine.

  20. Fully human broadly neutralizing monoclonal antibodies against influenza A viruses generated from the memory B cells of a 2009 pandemic H1N1 influenza vaccine recipient

    International Nuclear Information System (INIS)

    Hu, Weibin; Chen, Aizhong; Miao, Yi; Xia, Shengli; Ling, Zhiyang; Xu, Ke; Wang, Tongyan; Xu, Ying; Cui, Jun; Wu, Hongqiang; Hu, Guiyu; Tian, Lin; Wang, Lingling; Shu, Yuelong; Ma, Xiaowei; Xu, Bianli; Zhang, Jin; Lin, Xiaojun; Bian, Chao; Sun, Bing

    2013-01-01

    Whether the 2009 pandemic H1N1 influenza vaccine can induce heterosubtypic cross-protective anti-hemagglutinin (HA) neutralizing antibodies is an important issue. We obtained a panel of fully human monoclonal antibodies from the memory B cells of a 2009 pandemic H1N1 influenza vaccine recipient. Most of the monoclonal antibodies targeted the HA protein but not the HA1 fragment. Among the analyzed antibodies, seven mAbs exhibited neutralizing activity against several influenza A viruses of different subtypes. The conserved linear epitope targeted by the neutralizing mAbs (FIEGGWTGMVDGWYGYHH) is part of the fusion peptide on HA2. Our work suggests that a heterosubtypic neutralizing antibody response primarily targeting the HA stem region exists in recipients of the 2009 pandemic H1N1 influenza vaccine. The HA stem region contains various conserved neutralizing epitopes with the fusion peptide as an important one. This work may aid in the design of a universal influenza A virus vaccine.

  1. A heterologous prime-boost Ebola virus vaccine regimen induces durable neutralizing antibody response and prevents Ebola virus-like particle entry in mice.

    Science.gov (United States)

    Chen, Tan; Li, Dapeng; Song, Yufeng; Yang, Xi; Liu, Qingwei; Jin, Xia; Zhou, Dongming; Huang, Zhong

    2017-09-01

    Ebola virus (EBOV) is one of the most virulent pathogens known to humans. Neutralizing antibodies play a major role in the protection against EBOV infections. Thus, an EBOV vaccine capable of inducing a long-lasting neutralizing antibody response is highly desirable. We report here that a heterologous prime-boost vaccine regimen can elicit durable EBOV-neutralizing antibody response in mice. A chimpanzee serotype 7 adenovirus expressing EBOV GP (denoted AdC7-GP) was generated and used for priming. A truncated version of EBOV GP1 protein (denoted GP1t) was produced at high levels in Drosophila S2 cells and used for boosting. Mouse immunization studies showed that the AdC7-GP prime/GP1t boost vaccine regimen was more potent in eliciting neutralizing antibodies than either the AdC7-GP or GP1t alone. Neutralizing antibodies induced by the heterologous prime-boost regimen sustained at high titers for at least 18 weeks after immunization. Significantly, in vivo challenge studies revealed that the entry of reporter EBOV-like particles was efficiently blocked in mice receiving the heterologous prime-boost regimen even at 18 weeks after the final dose of immunization. These results suggest that this novel AdC7-GP prime/GP1t boost regimen represents an EBOV vaccine approach capable of establishing long-term protection, and therefore warrants further development. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Nasal Immunization Confers High Avidity Neutralizing Antibody Response and Immunity to Primary and Recurrent Genital Herpes in Guinea Pigs

    Science.gov (United States)

    Persson, Josefine; Zhang, Yuan; Olafsdottir, Thorunn A.; Thörn, Karolina; Cairns, Tina M.; Wegmann, Frank; Sattentau, Quentin J.; Eisenberg, Roselyn J.; Cohen, Gary H.; Harandi, Ali M.

    2016-01-01

    Genital herpes is one of the most prevalent sexually transmitted infections in both the developing and developed world. Following infection, individuals experience life-long latency associated with sporadic ulcerative outbreaks. Despite many efforts, no vaccine has yet been licensed for human use. Herein, we demonstrated that nasal immunization with an adjuvanted HSV-2 gD envelope protein mounts significant protection to primary infection as well as the establishment of latency and recurrent genital herpes in guinea pigs. Nasal immunization was shown to elicit specific T cell proliferative and IFN-γ responses as well as systemic and vaginal gD-specific IgG antibody (Ab) responses. Furthermore, systemic IgG Abs displayed potent HSV-2 neutralizing properties and high avidity. By employing a competitive surface plasmon resonance (SPR) analysis combined with a battery of known gD-specific neutralizing monoclonal Abs (MAbs), we showed that nasal immunization generated IgG Abs directed to two major discontinuous neutralizing epitopes of gD. These results highlight the potential of nasal immunization with an adjuvanted HSV-2 envelope protein for induction of protective immunity to primary and recurrent genital herpes. PMID:28082979

  3. Genome-wide association study on the development of cross-reactive neutralizing antibodies in HIV-1 infected individuals.

    Directory of Open Access Journals (Sweden)

    Zelda Euler

    Full Text Available Broadly neutralizing antibodies may protect against HIV-1 acquisition. In natural infection, only 10-30% of patients have cross-reactive neutralizing humoral immunity which may relate to viral and or host factors. To explore the role of host genetic markers in the formation of cross-reactive neutralizing activity (CrNA in HIV-1 infected individuals, we performed a genome-wide association study (GWAS, in participants of the Amsterdam Cohort Studies with known CrNA in their sera. Single-nucleotide polymorphisms (SNPs with the strongest P-values are located in the major histocompatibility complex (MHC region, close to MICA (P = 7.68 × 10(-7, HLA-B (P = 6.96 × 10(-6 and in the coding region of HCP5 (P = 1.34 × 10(-5. However, none of the signals reached genome-wide significance. Our findings underline the potential involvement of genes close or within the MHC region with the development of CrNA.

  4. Genome-Wide Association Study on the Development of Cross-Reactive Neutralizing Antibodies in HIV-1 Infected Individuals

    Science.gov (United States)

    Euler, Zelda; van Gils, Marit J.; Boeser-Nunnink, Brigitte D.; Schuitemaker, Hanneke; van Manen, Daniëlle

    2013-01-01

    Broadly neutralizing antibodies may protect against HIV-1 acquisition. In natural infection, only 10–30% of patients have cross-reactive neutralizing humoral immunity which may relate to viral and or host factors. To explore the role of host genetic markers in the formation of cross-reactive neutralizing activity (CrNA) in HIV-1 infected individuals, we performed a genome-wide association study (GWAS), in participants of the Amsterdam Cohort Studies with known CrNA in their sera. Single-nucleotide polymorphisms (SNPs) with the strongest P-values are located in the major histocompatibility complex (MHC) region, close to MICA (P = 7.68×10−7), HLA-B (P = 6.96×10−6) and in the coding region of HCP5 (P = 1.34×10−5). However, none of the signals reached genome-wide significance. Our findings underline the potential involvement of genes close or within the MHC region with the development of CrNA. PMID:23372753

  5. Nasal Immunization Confers High Avidity Neutralizing Antibody Response and Immunity to Primary and Recurrent Genital Herpes in Guinea Pigs.

    Science.gov (United States)

    Persson, Josefine; Zhang, Yuan; Olafsdottir, Thorunn A; Thörn, Karolina; Cairns, Tina M; Wegmann, Frank; Sattentau, Quentin J; Eisenberg, Roselyn J; Cohen, Gary H; Harandi, Ali M

    2016-01-01

    Genital herpes is one of the most prevalent sexually transmitted infections in both the developing and developed world. Following infection, individuals experience life-long latency associated with sporadic ulcerative outbreaks. Despite many efforts, no vaccine has yet been licensed for human use. Herein, we demonstrated that nasal immunization with an adjuvanted HSV-2 gD envelope protein mounts significant protection to primary infection as well as the establishment of latency and recurrent genital herpes in guinea pigs. Nasal immunization was shown to elicit specific T cell proliferative and IFN-γ responses as well as systemic and vaginal gD-specific IgG antibody (Ab) responses. Furthermore, systemic IgG Abs displayed potent HSV-2 neutralizing properties and high avidity. By employing a competitive surface plasmon resonance (SPR) analysis combined with a battery of known gD-specific neutralizing monoclonal Abs (MAbs), we showed that nasal immunization generated IgG Abs directed to two major discontinuous neutralizing epitopes of gD. These results highlight the potential of nasal immunization with an adjuvanted HSV-2 envelope protein for induction of protective immunity to primary and recurrent genital herpes.

  6. Human Monoclonal Antibodies against West Nile Virus Induced by Natural Infection Neutralize at a Postattachment Step

    NARCIS (Netherlands)

    Vogt, Matthew R.; Moesker, Bastiaan; Goudsmit, Jaap; Jongeneelen, Mandy; Austin, S. Kyle; Oliphant, Theodore; Nelson, Steevenson; Pierson, Theodore C.; Wilschut, Jan; Throsby, Mark; Diamond, Michael S.

    West Nile virus (WNV) is a neurotropic flavivirus that is now a primary cause of epidemic encephalitis in North America. Studies of mice have demonstrated that the humoral immune response against WNV limits primary infection and protects against a secondary challenge. The most-potent neutralizing

  7. Boosting of HIV-1 neutralizing antibody responses by a distally related retroviral envelope protein

    DEFF Research Database (Denmark)

    Uchtenhagen, Hannes; Schiffner, Torben; Bowles, Emma

    2014-01-01

    Our knowledge of the binding sites for neutralizing Abs (NAb) that recognize a broad range of HIV-1 strains (bNAb) has substantially increased in recent years. However, gaps remain in our understanding of how to focus B cell responses to vulnerable conserved sites within the HIV-1 envelope glycop...

  8. A neutralizing human monoclonal antibody protects against lethal disease in a new ferret model of acute nipah virus infection.

    Directory of Open Access Journals (Sweden)

    Katharine N Bossart

    2009-10-01

    Full Text Available Nipah virus is a broadly tropic and highly pathogenic zoonotic paramyxovirus in the genus Henipavirus whose natural reservoirs are several species of Pteropus fruit bats. Nipah virus has repeatedly caused outbreaks over the past decade associated with a severe and often fatal disease in humans and animals. Here, a new ferret model of Nipah virus pathogenesis is described where both respiratory and neurological disease are present in infected animals. Severe disease occurs with viral doses as low as 500 TCID(50 within 6 to 10 days following infection. The underlying pathology seen in the ferret closely resembles that seen in Nipah virus infected humans, characterized as a widespread multisystemic vasculitis, with virus replicating in highly vascular tissues including lung, spleen and brain, with recoverable virus from a variety of tissues. Using this ferret model a cross-reactive neutralizing human monoclonal antibody, m102.4, targeting the henipavirus G glycoprotein was evaluated in vivo as a potential therapeutic agent. All ferrets that received m102.4 ten hours following a high dose oral-nasal Nipah virus challenge were protected from disease while all controls died. This study is the first successful post-exposure passive antibody therapy for Nipah virus using a human monoclonal antibody.

  9. Rapid Transient Production of a Monoclonal Antibody Neutralizing the Porcine Epidemic Diarrhea Virus (PEDV) in Nicotiana benthamiana and Lactuca sativa.

    Science.gov (United States)

    Rattanapisit, Kaewta; Srijangwad, Anchalee; Chuanasa, Taksina; Sukrong, Suchada; Tantituvanont, Angkana; Mason, Hugh S; Nilubol, Dachrit; Phoolcharoen, Waranyoo

    2017-12-01

    Porcine epidemic diarrhea virus (PEDV) causes acute diarrhea, vomiting, dehydration, weight loss, and high mortality rate in neonatal piglets. Porcine epidemic diarrhea (PED) has been reported in Europe, America, and Asia including Thailand. The disease causes substantial losses to the swine industry in many countries. Presently, there is no effective PEDV vaccine available. In this study, we developed a plant-produced monoclonal antibody (mAb) 2C10 as a prophylactic candidate to prevent the PEDV infection. Recently, plant expression systems have gained interest as an alternative for the production of antibodies because of many advantages, such as low production cost, lack of human and animal pathogen, large scalability, etc. The 2C10 mAb was transiently expressed in Nicotiana benthamiana and lettuce using geminiviral vector. After purification by protein A affinity chromatography, the antibody was tested for the binding and neutralizing activity against PEDV. Our result showed that the plant produced 2C10 mAb can bind to the virus and also inhibit PEDV infection in vitro . These results show excellent potential for a plant-expressed 2C10 as a PEDV prophylaxis and a diagnostic for PEDV infection. Georg Thieme Verlag KG Stuttgart · New York.

  10. Adaptation of the neutral bacterial comet assay to assess antimicrobial-mediated DNA double-strand breaks in Escherichia coli

    Science.gov (United States)

    SOLANKY, DIPESH; HAYDEL, SHELLEY E.

    2012-01-01

    This study aimed to determine the mechanism of action of a natural antibacterial clay mineral mixture, designated CB, by investigating the induction of DNA double-strand breaks (DSBs) in Escherichia coli. To quantify DNA damage upon exposure to soluble antimicrobial compounds, we modified a bacterial neutral comet assay, which primarily associates the general length of an electrophoresed chromosome, or comet, with the degree of DSB-associated DNA damage. To appropriately account for antimicrobial-mediated strand fragmentation, suitable control reactions consisting of exposures to water, ethanol, kanamycin, and bleomycin were developed and optimized for the assay. Bacterial exposure to the CB clay resulted in significantly longer comet lengths, compared to water and kanamycin exposures, suggesting that the induction of DNA DSBs contributes to the killing activity of this antibacterial clay mineral mixture. The comet assay protocol described herein provides a general technique for evaluating soluble antimicrobial-derived DNA damage and for comparing DNA fragmentation between experimental and control assays. PMID:22940101

  11. Human vaccination against RH5 induces neutralizing antimalarial antibodies that inhibit RH5 invasion complex interactions

    DEFF Research Database (Denmark)

    Payne, Ruth O; Silk, Sarah E; Elias, Sean C

    2017-01-01

    serum antibodies exhibited cross-strain functional growth inhibition activity (GIA) in vitro, targeted linear and conformational epitopes within RH5, and inhibited key interactions within the RH5 invasion complex. This is the first time to our knowledge that substantial RH5-specific responses have been...

  12. Comparison of assays for the detection of West Nile virus antibodies in equine serum after natural infection or vaccination

    Czech Academy of Sciences Publication Activity Database

    Joó, K.; Bakonyi, T.; Szenci, O.; Ferenczi, E.; Barna, M.; Malik, P.; Hubálek, Zdeněk; Fehér, O.; Kutasi, O.

    2017-01-01

    Roč. 183, č. 1 (2017), s. 1-6 ISSN 0165-2427 Institutional support: RVO:68081766 Keywords : West Nile virus * Haemagglutination-inhibition test * Enzymelinked immunosorbent assay * Plaque reduction neutralization test * Vaccination * Natural infection Subject RIV: FN - Epidemiology, Contagious Diseases ; Clinical Immunology OBOR OECD: Immunology Impact factor: 1.718, year: 2016

  13. Thyroglobulin (Tg) recovery testing with quantitative Tg antibody measurement for determining interference in serum Tg assays in differentiated thyroid carcinoma

    NARCIS (Netherlands)

    Persoon, ACM; Links, TP; Wilde, J; Sluiter, WJ; Wolffenbuttel, BHR; van den Ouweland, JMW

    Background: Thyroglobulin (Tg) measurements are complicated by interference from Tg autoantibodies (TgAbs) or heterophilic antibodies (HAMAs). We used a new automated immunochemiluminometric assay (ICMA) with Tg recovery (TgR) on the Nichols Advantage (R) platform to reassess the clinical utility of

  14. Comparison of different assays to assess human papillomavirus (HPV) type 16- and 18-specific antibodies after HPV infection and vaccination

    NARCIS (Netherlands)

    Scherpenisse, Mirte; Schepp, Rutger M.; Mollers, Madelief; Mooij, Sofie H.; Meijer, Chris J. L. M.; Berbers, Guy A. M.; van der Klis, Fiona R. M.

    2013-01-01

    We compared the measurement of human papillomavirus (HPV)-specific serum antibody levels with the virus-like-particle multiplex immunoassay (VLP-MIA), competitive Luminex immunoassay (cLIA), and glutathione S-transferase (GST) L1-based MIA. Using a large panel of serum samples, these assays showed

  15. Enzyme linked immunosorbent assay for detecting antibody to Trichomonas vaginalis: use of whole cells and aqueous extract as antigen.

    Science.gov (United States)

    Alderete, J F

    1984-06-01

    An enzyme linked immunosorbent assay (ELISA) for detecting antibody to antigenic Trichomonas vaginalis macromolecules has been identified using whole cells or an aqueous protein extract as antigen. The test was developed under optimum conditions using serum samples from experimental animals. The sensitivity of the ELISA was equal to or greater than that obtained by radioimmunoprecipitation and electrophoresis-fluorography techniques. The ELISA was capable of assessing antibody responses during the development of lesions in animals inoculated subcutaneously and it reproducibly measured the individual classes immunoglobulins directed at T vaginalis. The colorimetric assay was also suitable for showing cross reactivity between trichomonal species as well as between different strains of T vaginalis. Conditions established for monitoring antibody to trichomanads in immunised rabbits or infected mice were equally effective for human materials, such as serum or vaginal washes. Serum from experimental animals or infected people showed high concentrations of IgG, IgA, and IgM antibody to trichomonads. Only antibodies of the IgG and IgA class were detected in vaginal washes from women with acute trichomoniasis. No IgE antibody to trichomonads was found under a variety of conditions in serum samples from patients or experimental animals.

  16. Detection of serum anti-sperm antibody in infertile couples with dot-immunogold filtration assay (DIGFA)

    International Nuclear Information System (INIS)

    Xie Xiaoxian

    2005-01-01

    Objective: To develop a new method for rapid detection of serum anti-sperm antibody in infertile couples. Methods: Human sperm antigen was prepared from pooled semen specimens of fertile males. Nitro-cellulose membrane was used as solid-phase carrier of the antigen. Colloidal gold pellet combined goat anti-human IgG was taken as labelled antibody. A dot-immunogold filtration assay system was established for test of serum anti-human sperm antibody. Serum specimens from 137 infertile couples were tested and the result compared with flat from ELISA. Results: The human sperm antigen would react with the anti-sperm antibody in the tested serum over the cellulose membrane through filtration and the result could be read with naked eye within 6 minutes. In this study of 137 infertile coupled, the anti-sperm antibody was positive in 21.9% of the female serum specimens and 13.19% of the males. Compared with the result from ELISA, the consistency rate was 96.1%. The sensitivity of the assay was 90.2% and specificity was 95.4%. The p reparation was stable after 6 months refrigerator storage. Conclusion: This newly developed DIGFA is very adequate for rap id detection of anti-sperm antibody and deserves popularization. (authors)

  17. Tus-Ter-lock immuno-PCR assays for the sensitive detection of tropomyosin-specific IgE antibodies.

    Science.gov (United States)

    Johnston, Elecia B; Kamath, Sandip D; Lopata, Andreas L; Schaeffer, Patrick M

    2014-02-01

    The increasing prevalence of food allergies requires development of specific and sensitive tests capable of identifying the allergen responsible for the disease. The development of serologic tests that can detect specific IgE antibodies to allergenic proteins would, therefore, be highly received. Here we present two new quantitative immuno-PCR assays for the sensitive detection of antibodies specific to the shrimp allergen tropomyosin. Both assays are based on the self-assembling Tus-Ter-lock protein-DNA conjugation system. Significantly elevated levels of tropomyosin-specific IgE were detected in sera from patients allergic to shrimp. This is the first time an allergenic protein has been fused with Tus to enable specific IgE antibody detection in human sera by quantitative immuno-PCR.

  18. Enzyme-linked immunosorbent assay for total sennosides using anti-sennside A and anti-sennoside B monoclonal antibodies.

    Science.gov (United States)

    Morinaga, Osamu; Uto, Takuhiro; Sakamoto, Seiichi; Tanaka, Hiroyuki; Shoyama, Yukihiro

    2009-01-01

    Total sennosides concentration is a very important factor when rhubarb and senna will be used as crude drugs. However, one-step analytical technique for total sennosides has not been reported except HPLC. An enzyme-linked immunosorbent assay (ELISA) for total sennosides concentration by using the combination of anti-sennoside A (SA) and anti-sennoside B (SB) monoclonal antibodies (MAbs) in a single assay has been investigated. Total sennosides concentration in rhubarb and senna samples determined by newly developed assay system showed good agreement with those analyzed by ELISA using anti-SA MAb and anti-SB MAb, respectively.

  19. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. An alphavirus vector overcomes the presence of neutralizing antibodies and elevated numbers of Tregs to induce immune responses in humans with advanced cancer.

    Science.gov (United States)

    Morse, Michael A; Hobeika, Amy C; Osada, Takuya; Berglund, Peter; Hubby, Bolyn; Negri, Sarah; Niedzwiecki, Donna; Devi, Gayathri R; Burnett, Bruce K; Clay, Timothy M; Smith, Jonathan; Lyerly, H Kim

    2010-09-01

    Therapeutic anticancer vaccines are designed to boost patients' immune responses to tumors. One approach is to use a viral vector to deliver antigen to in situ DCs, which then activate tumor-specific T cell and antibody responses. However, vector-specific neutralizing antibodies and suppressive cell populations such as Tregs remain great challenges to the efficacy of this approach. We report here that an alphavirus vector, packaged in virus-like replicon particles (VRP) and capable of efficiently infecting DCs, could be repeatedly administered to patients with metastatic cancer expressing the tumor antigen carcinoembryonic antigen (CEA) and that it overcame high titers of neutralizing antibodies and elevated Treg levels to induce clinically relevant CEA-specific T cell and antibody responses. The CEA-specific antibodies mediated antibody-dependent cellular cytotoxicity against tumor cells from human colorectal cancer metastases. In addition, patients with CEA-specific T cell responses exhibited longer overall survival. These data suggest that VRP-based vectors can overcome the presence of neutralizing antibodies to break tolerance to self antigen and may be clinically useful for immunotherapy in the setting of tumor-induced immunosuppression.

  1. A novel variable antibody fragment dimerized by leucine zippers with enhanced neutralizing potency against rabies virus G protein compared to its corresponding single-chain variable antibody fragment.

    Science.gov (United States)

    Li, Zhuang; Cheng, Yue; Xi, Hualong; Gu, Tiejun; Yuan, Ruosen; Chen, Xiaoxu; Jiang, Chunlai; Kong, Wei; Wu, Yongge

    2015-12-01

    Fatal rabies can be prevented effectively by post-exposure prophylactic (PEP) with rabies immunoglobulin (RIG). Single-chain variable fragments (scFv), which are composed of a variable heavy chain (VH) and a variable light chain (VL) connected by a peptide linker, can potentially be used to replace RIG. However, in our previous study, a scFv (scFV57S) specific for the rabies virus (RV) G protein showed a lower neutralizing potency than that of its parent IgG due to lower stability and altered peptide assembly pattern. In monoclonal antibodies, the VH and VL interact non-covalently, while in scFvs the VH is connected covalently with the VL by the artificial linker. In this study, we constructed and expressed two peptides 57VL-JUN-HIS and 57VH-FOS-HA in Escherichia coli. The well-known Fos and Jun leucine zippers were utilized to dimerize VH and VL similarly to the IgG counterpart. The two peptides assembled to form zipFv57S in vitro. Due to the greater similarity in structure with IgG, the zipFv57S protein showed a higher binding ability and affinity resulting in notable improvement of in vitro neutralizing activity over its corresponding scFv. The zipFv57S protein was also found to be more stable and showed similar protective rate as RIG in mice challenged with a lethal dose of RV. Our results not only indicated zipFv57S as an ideal alternative for RIG in PEP but also offered a novel and efficient hetero-dimerization pattern of VH and VL leading to enhanced neutralizing potency. Copyright © 2015. Published by Elsevier Ltd.

  2. Identification of a vesicular-arbuscular mycorrhizal fungus by using monoclonal antibodies in an enzyme-linked immunosorbent assay.

    Science.gov (United States)

    Wright, S F; Morton, J B; Sworobuk, J E

    1987-09-01

    Spore morphology is currently used to identify species of vesicular-arbuscular mycorrhizal fungi. We report the first use of a highly specific immunological method for identification of a vesicular-arbuscular mycorrhizal fungus. Two monoclonal antibodies were produced against Glomus occultum. Monoclonal antibodies reacted strongly with both spores and hyphae in an indirect enzyme-linked immunosorbent assay. All other mycorrhizal (29 species) and nonmycorrhizal (5 species) fungi tested were nonreactive with the monoclonal antibodies. A single spore of G. occultum was detectable in the presence of high numbers of spores of other vesicular-arbuscular mycorrhizal fungi. Variation in the reaction of G. occultum isolates from West Virginia, Florida, and Colombia suggests that monoclonal antibodies may differentiate strains.

  3. Binding of HIV-1 gp41-directed neutralizing and non-neutralizing fragment antibody binding domain (Fab and single chain variable fragment (ScFv antibodies to the ectodomain of gp41 in the pre-hairpin and six-helix bundle conformations.

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    John M Louis

    Full Text Available We previously reported a series of antibodies, in fragment antigen binding domain (Fab formats, selected from a human non-immune phage library, directed against the internal trimeric coiled-coil of the N-heptad repeat (N-HR of HIV-1 gp41. Broadly neutralizing antibodies from that series bind to both the fully exposed N-HR trimer, representing the pre-hairpin intermediate state of gp41, and to partially-exposed N-HR helices within the context of the gp41 six-helix bundle. While the affinities of the Fabs for pre-hairpin intermediate mimetics vary by only 2 to 20-fold between neutralizing and non-neutralizing antibodies, differences in inhibition of viral entry exceed three orders of magnitude. Here we compare the binding of neutralizing (8066 and non-neutralizing (8062 antibodies, differing in only four positions within the CDR-H2 binding loop, in Fab and single chain variable fragment (ScFv formats, to several pre-hairpin intermediate and six-helix bundle constructs of gp41. Residues 56 and 58 of the mini-antibodies are shown to be crucial for neutralization activity. There is a large differential (≥ 150-fold in binding affinity between neutralizing and non-neutralizing antibodies to the six-helix bundle of gp41 and binding to the six-helix bundle does not involve displacement of the outer C-terminal helices of the bundle. The binding stoichiometry is one six-helix bundle to one Fab or three ScFvs. We postulate that neutralization by the 8066 antibody is achieved by binding to a continuum of states along the fusion pathway from the pre-hairpin intermediate all the way to the formation of the six-helix bundle, but prior to irreversible fusion between viral and cellular membranes.

  4. Monoclonal antibodies directed to E1 glycoprotein of rubella virus

    International Nuclear Information System (INIS)

    Umino, Y.; Sato, A.; Katow, S.; Matsuno, T.; Sugiura, A.

    1985-01-01

    We have prepared four monoclonal antibodies to rubella virus E1 glycoprotein. Three nonoverlapping antigenic sites were delineated on E1 protein by competitive binding assays. Antibodies binding to one site were characterized by high hemagglutination inhibition (HI) titer but poor neutralizing activity. The addition of antiglobulin conferred neutralizing activity. Antibodies directed to two other antigenic sites had modest hemolysis inhibition but little or no HI and neutralizing activities. The addition of antiglobulin markedly augmented HI activity but had little effect on neutralizing activity. Epitopes defined by three antibodies were conserved among four rubella virus strains examined. (Author)

  5. Synthetic B-Cell Epitopes Eliciting Cross-Neutralizing Antibodies: Strategies for Future Dengue Vaccine.

    Directory of Open Access Journals (Sweden)

    Babu Ramanathan

    Full Text Available Dengue virus (DENV is a major public health threat worldwide. A key element in protection from dengue fever is the neutralising antibody response. Anti-dengue IgG purified from DENV-2 infected human sera showed reactivity against several peptides when evaluated by ELISA and epitope extraction techniques. A multi-step computational approach predicted six antigenic regions within the E protein of DENV-2 that concur with the 6 epitopes identified by the combined ELISA and epitope extraction approach. The selected peptides representing B-cell epitopes were attached to a known dengue T-helper epitope and evaluated for their vaccine potency. Immunization of mice revealed two novel synthetic vaccine constructs that elicited good humoral immune responses and produced cross-reactive neutralising antibodies against DENV-1, 2 and 3. The findings indicate new directions for epitope mapping and contribute towards the future development of multi-epitope based synthetic peptide vaccine.

  6. Antibody-based assay discriminates Zika virus infection from other flaviviruses.

    Science.gov (United States)

    Balmaseda, Angel; Stettler, Karin; Medialdea-Carrera, Raquel; Collado, Damaris; Jin, Xia; Zambrana, José Victor; Jaconi, Stefano; Cameroni, Elisabetta; Saborio, Saira; Rovida, Francesca; Percivalle, Elena; Ijaz, Samreen; Dicks, Steve; Ushiro-Lumb, Ines; Barzon, Luisa; Siqueira, Patricia; Brown, David W G; Baldanti, Fausto; Tedder, Richard; Zambon, Maria; de Filippis, A M Bispo; Harris, Eva; Corti, Davide

    2017-08-01

    Zika virus (ZIKV) is a mosquito-borne flavivirus that emerged recently as a global health threat, causing a pandemic in the Americas. ZIKV infection mostly causes mild disease, but is linked to devastating congenital birth defects and Guillain-Barré syndrome in adults. The high level of cross-reactivity among flaviviruses and their cocirculation has complicated serological approaches to differentially detect ZIKV and dengue virus (DENV) infections, accentuating the urgent need for a specific and sensitive serological test. We previously generated a ZIKV nonstructural protein 1 (NS1)-specific human monoclonal antibody, which we used to develop an NS1-based competition ELISA. Well-characterized samples from RT-PCR-confirmed patients with Zika and individuals exposed to other flavivirus infections or vaccination were used in a comprehensive analysis to determine the sensitivity and specificity of the NS1 blockade-of-binding (BOB) assay, which was established in laboratories in five countries (Nicaragua, Brazil, Italy, United Kingdom, and Switzerland). Of 158 sera/plasma from RT-PCR-confirmed ZIKV infections, 145 (91.8%) yielded greater than 50% inhibition. Of 171 patients with primary or secondary DENV infections, 152 (88.9%) scored negative. When the control group was extended to patients infected by other flaviviruses, other viruses, or healthy donors ( n = 540), the specificity was 95.9%. We also analyzed longitudinal samples from DENV-immune and DENV-naive ZIKV infections and found inhibition was achieved within 10 d postonset of illness and maintained over time. Thus, the Zika NS1 BOB assay is sensitive, specific, robust, simple, low-cost, and accessible, and can detect recent and past ZIKV infections for surveillance, seroprevalence studies, and intervention trials.

  7. An enzyme-linked immuno-filtration assay used to compare infant and maternal antibody profiles in toxoplasmosis.

    Science.gov (United States)

    Pinon, J M; Thoannes, H; Gruson, N

    1985-02-28

    Enzyme-linked immuno-filtration assay is carried out on a micropore membrane. This doubly analytical technique permits simultaneous study of antibody specificity by immunoprecipitation and characterisation of antibody isotypes by immuno-filtration with enzyme-labelled antibodies. Recognition of the same T. gondii antigenic constituent by IgG, IgA, IgM or IgE antibodies produces couplets (IgG-IgM; IgG-IgA) or triplets (IgG-IgM-IgA; IgG-IgM-IgE) which identify the functional fractions of the toxoplasmosis antigen. In acquired toxoplasmosis, the persistence of IgM antibody long after infestation puts in question the implication of recent infestation normally linked to detection of this isotype. For sera of comparable titres, comparison of immunological profiles by the method described demonstrates disparities in the composition of the specific antibody content as expressed in international units. Use of the same method to detect IgM antibodies or distinguish between transmitted maternal IgG and IgG antibodies synthesised by the foetus or neonate makes a diagnosis of congenital toxoplasmosis possible in 85% of cases during the first few days of life. With the method described the diagnosis may be made on average 5 months earlier than with classical techniques. In the course of surveillance for latent congenital toxoplasmosis, the appearance of IgM or IgE antibodies raises the possibility of complications (hydrocephalus, chorioretinitis). After cessation of treatment, a rise in IgG antibodies indicating persistence of infection is detected earlier by the present than by classical methods.

  8. High Epstein-Barr Virus Load and Genomic Diversity Are Associated with Generation of gp350-Specific Neutralizing Antibodies following Acute Infectious Mononucleosis.

    Science.gov (United States)

    Weiss, Eric R; Alter, Galit; Ogembo, Javier Gordon; Henderson, Jennifer L; Tabak, Barbara; Bakiş, Yasin; Somasundaran, Mohan; Garber, Manuel; Selin, Liisa; Luzuriaga, Katherine

    2017-01-01

    The Epstein-Barr virus (EBV) gp350 glycoprotein interacts with the cellular receptor to mediate viral entry and is thought to be the major target for neutralizing antibodies. To better understand the role of EBV-specific antibodies in the control of viral replication and the evolution of sequence diversity, we measured EBV gp350-specific antibody responses and sequenced the gp350 gene in samples obtained from individuals experiencing primary EBV infection (acute infectious mononucleosis [AIM]) and again 6 months later (during convalescence [CONV]). EBV gp350-specific IgG was detected in the sera of 17 (71%) of 24 individuals at the time of AIM and all 24 (100%) individuals during CONV; binding antibody titers increased from AIM through CONV, reaching levels equivalent to those in age-matched, chronically infected individuals. Antibody-dependent cell-mediated phagocytosis (ADCP) was rarely detected during AIM (4 of 24 individuals; 17%) but was commonly detected during CONV (19 of 24 individuals; 79%). The majority (83%) of samples taken during AIM neutralized infection of primary B cells; all samples obtained at 6 months postdiagnosis neutralized EBV infection of cultured and primary target cells. Deep sequencing revealed interpatient gp350 sequence variation but conservation of the CR2-binding site. The levels of gp350-specific neutralizing activity directly correlated with higher peripheral blood EBV DNA levels during AIM and a greater evolution of diversity in gp350 nucleotide sequences from AIM to CONV. In summary, we conclude that the viral load and EBV gp350 diversity during early infection are associated with the development of neutralizing antibody responses following AIM. Antibodies against viral surface proteins can blunt the spread of viral infection by coating viral particles, mediating uptake by immune cells, or blocking interaction with host cell receptors, making them a desirable component of a sterilizing vaccine. The EBV surface protein gp350 is a

  9. Structure of an N276-Dependent HIV-1 Neutralizing Antibody Targeting a Rare V5 Glycan Hole Adjacent to the CD4 Binding Site

    Energy Technology Data Exchange (ETDEWEB)

    Wibmer, Constantinos Kurt; Gorman, Jason; Anthony, Colin S.; Mkhize, Nonhlanhla N.; Druz, Aliaksandr; York, Talita; Schmidt, Stephen D.; Labuschagne, Phillip; Louder, Mark K.; Bailer, Robert T.; Karim, Salim S. Abdool; Mascola, John R.; Williamson, Carolyn; Moore, Penny L.; Kwong, Peter D.; Morris, Lynn (NHLS-South Africa); (NIH); (Witwatersrand); (KwaZulu-Natal)

    2016-08-31

    ABSTRACT

    All HIV-1-infected individuals develop strain-specific neutralizing antibodies to their infecting virus, which in some cases mature into broadly neutralizing antibodies. Defining the epitopes of strain-specific antibodies that overlap conserved sites of vulnerability might provide mechanistic insights into how broadly neutralizing antibodies arise. We previously described an HIV-1 clade C-infected donor, CAP257, who developed broadly neutralizing plasma antibodies targeting an N276 glycan-dependent epitope in the CD4 binding site. The initial CD4 binding site response potently neutralized the heterologous tier 2 clade B viral strain RHP