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The current approaches of diagnostic platforms for detecting SARS-CoV-2 infections mostly relied on adapting the existing technology. In this work, a simple and low-cost electrochemical sensing platform for detecting SAR-CoV-2 antigen was established. The proposed sensor combined the innovative disposable paper-based immunosensor and cost-effective plant-based anti-SARS-CoV-2 monoclonal antibody CR3022, expressed in Nicotiana benthamiana. The cellulose nanocrystal was modified on screen-printed graphene electrode to provide the abundant COOH functional groups on electrode surface, leading to the high ability for antibody immobilization. The quantification of the presence receptor binding domain (RBD) spike protein of SARS-CoV-2 was performed using differential pulse voltammetry by monitoring the changing current of [Fe(CN) 6 ]3-/4- redox solution. The current change of [Fe(CN) 6 ]3-/4- before and after the presence of target RBD could be clearly distinguished, providing a linear relationship with RBD concentration in the range from 0.1 pg/mL to 500 ng/mL with the minimum limit of detection of 2.0 fg/mL. The proposed platform was successfully applied to detect RBD in nasopharyngeal swab samples with satisfactory results. Furthermore, the paper-based immunosensor was extended to quantify the RBD level in spiked saliva samples, demonstrating the broadly applicability of this system. This electrochemical paper-based immunosensor has the potential to be employed as a point-of-care testing for COVID-19 diagnosis. [Display omitted] • The electrochemical paper-based device integrated with a label-free immunoassay was developed for detecting SARS-CoV-2. • A novel plant-based mAb CR3022 offers a remarkable simplicity and cost-effectiveness in terms of Ab production. • CNC containing the abundant COOH functional groups has the potential to be used as the immobilizing material. • The proposed immunosensor was successfully applied to detect SARS-CoV-2 from nasopharyngeal swabs and saliva samples. [ABSTRACT FROM AUTHOR]

Background: A simple filter paper method was developed for, the transport and storage of monoclonal antibodies (Mabs) at room temperature or -20°C after spotting on filter paper, for subsequent sero-typing of outer membrane antigens of N.meningitidis by dot-blot ELISA. Methods: Monoclonal antibodies (Mabs) were spotted within a 0.5-1 cm diameter area of Whatman grade 903 paper, which were stored individually at room temperature or at -20°C. These MAbs were stored and analyzed after periods of one week, 4 weeks, 12 months, or 13 years in the case of frozen Mab aliquots, or after 4 weeks at -20°C or at room temperature (RT) in the case of Mabs dried on filter paper strips. Assays were performed in parallel using dot-blot ELISA. In addition to the MAbs specific for serotyping class 1, 2 or 3, we used a larger number of Mabs for polysaccharides, lipooligosaccharides (LOS), class 5 and cross-reactive antigens for native outer membrane of N.meningitidis. The Mabs dried on filter paper were eluted with phosphate-buffered saline (PBS) containing 0.2% gelatin. Results: Mabs of the isotypes IgG and IgM dried on filter papers were not affected by duration of storage. The detection by serotyping Mabs was generally consistent for dried filter paper MAb samples stored frozen for over 1 year at -20°C, and although decreased reactive antibody titers were found after storage, this did not interfere with the specificity of the Mabs used after 13 years as dry spots on filter paper. Conclusion: The use of filter paper is an inexpensive and convenient method for collecting, storing, and transporting Mab samples for serotyping studies. In addition, the samples occupy little space and can be readily transported without freezing. The efficiency of using immunoglobulin G (IgG) or M (IgM) eluted was found to be consistent with measurement of IgG or IgM titers in most corresponding, ascites Mabs stored frozen for over 1 year. The application of meningococcal typing methods and designations depend on the question being asked. [ABSTRACT FROM AUTHOR]

Novel antibodies have been generated by immunizing with bacterially expressed fragments of the repetitive motif of the Ki-67 gene. One such antibody, MIB1, recognizes a fixation and embedding resistant epitope on the Ki-67 protein if sections are previously microwaved in a citrate buffer. We have investigated the utility of this antibody as a marker of cell proliferation in archival material. The microwave technique is simple but requires careful monitoring since different tissues and fixatives require different irradiation times. Strong nuclear immunoreactivity was detected with all fixatives studied. Cytoplasmic staining was not identified. In a wide range of normal tissues the distribution and number of MIB1 immunoreactive cells matched that of cryostat sections stained with Ki-67. In nude mouse xenografts in which the growth fraction had been defined using a fraction of labelled mitosis method, the labelling index with MIB1 matched that previously determined for Ki-67 and correlated well with the growth fraction. Other markers of proliferation (e.g. proliferating cell nulcear antigen) have been shown to be expressed in DNA repair, thus we investigated expression of MIB1 immunoreactivity in situations of DNA repair in vivo—ultraviolet irradiated human skin. MIB1 staining correlated with semi-conservative DNA synthesis rather than excision repair DNA synthesis. Finally, the morphological and cell cycle distribution of MIB1 expression is identical to that of Ki-67. Thus, MIB1 represents a new anti-Ki-67 antibody which appears to be a robust marker of cell proliferation easily applicable to archival material. [ABSTRACT FROM AUTHOR]

There are no assays for detecting B. burgdorferi antigen in blood of infected Lyme disease individuals. Here, we provide proof-of-principle evidence that we can quantify B. burgdorferi antigen in spiked blood using a portable smartphone-based fluorescence microscope that measures immunoagglutination on a paper microfluidic chip. We targeted B. burgdorferi OspA to develop a working prototype and added examples of two antigens (OspC and VlsE) that have diagnostic value for discrimination of Lyme disease stage. Using an extensively validated monoclonal antibody to OspA (LA-2), detection of OspA antigen had a broad linear range up to 100 pg/mL in 1% blood and the limit of detection (LOD) was 100 fg/mL (= 10 pg/mL in undiluted blood), which was 1000 times lower than our target of 10 ng/mL. Analysis of the two other targets was done using polyclonal and monoclonal antibodies. OspC antigen was detected at LOD 100 pg/mL (= 10 ng/mL of undiluted blood) and VlsE antigen was detected at LOD 1–10 pg/mL (= 0.1–1 ng/mL of undiluted blood). The method is accurate and was performed in 20 min from sample to answer. When optimized for detecting several B. burgdorferi antigens, this assay may differentiate active from past infections and facilitate diagnosis of Lyme disease in the initial weeks of infection, when antibody presence is typically below the threshold to be detected by serologic methods. [ABSTRACT FROM AUTHOR]

This paper presents the effects of the composition of different media (i.e., Tryptic soy broth (TSB), Brain heart infusion (BHI), Listeria enrichment broth (LEB), Fraser broth (FB) and University of Vermont medium (UVM)) on the detection of a short peptide fragment PepD specific to the p60 protein (p60) of L. monocytogenes by a monoclonal antibody (anti-PepD mAb). Expression of the p60 obtained was demonstrated to be proportional to the cellular growth of Listeria monocytogenes regardless of the tested growth medium. However, the early growth of L. monocytogenes and the expression of the p60 were negatively affected by the presence of selective agents present in LEB, FB and UVM. Among those three selective enrichment media commonly used for L. monocytogenes , LEB allowed a better expression of L. monocytogenes p60 after an incubation period of 18 h. Optimization of the LEB revealed that the dextrose concentration was the critical factor for improving the expression of p60 and promotes the early expression of p60. Moreover, an optimal dextrose concentration of 0.5% (w/v) in LEB, coupled with anti-PepD mAb immobilized to solid support, reduced the detection of p60 from 18 h to 9 h for an initial concentration of L. monocytogenes of 108 CFU/ml. [ABSTRACT FROM AUTHOR]

Hepatitis A virus (HAV), an enigmatic and ancient pathogen, is a major causative agent of acute viral hepatitis worldwide. Although there are effective vaccines, antivirals against HAV infection are still required, especially during fulminant hepatitis outbreaks. A more in-depth understanding of the antigenic characteristics of HAV and the mechanisms of neutralization could aid in the development of rationally designed antiviral drugs targeting HAV. In this paper, 4 new antibodies—F4, F6, F7, and F9—are reported that potently neutralize HAV at 50% neutralizing concentration values (neut50) ranging from 0.1 nM to 0.85 nM. High-resolution cryo-electron microscopy (cryo-EM) structures of HAV bound to F4, F6, F7, and F9, together with results of our previous studies on R10 fragment of antigen binding (Fab)-HAV complex, shed light on the locations and nature of the epitopes recognized by the 5 neutralizing monoclonal antibodies (NAbs). All the epitopes locate within the same patch and are highly conserved. The key structure-activity correlates based on the antigenic sites have been established. Based on the structural data of the single conserved antigenic site and key structure-activity correlates, one promising drug candidate named golvatinib was identified by in silico docking studies. Cell-based antiviral assays confirmed that golvatinib is capable of blocking HAV infection effectively with a 50% inhibitory concentration (IC50) of approximately 1 μM. These results suggest that the single conserved antigenic site from complete HAV capsid is a good antiviral target and that golvatinib could function as a lead compound for anti-HAV drug development. [ABSTRACT FROM AUTHOR]

This paper reports isolation of two monoclonal antibodies (mAbs) that bind to both a membrane protein and a cytoplasmic protein. Most Abs established as markers for autoimmune disease bind to cytoplasmic or nuclear substances. However, it remains unknown how these Abs are produced. On the other hand, there were examples where clones originally isolated as Abs that bind to membrane proteins also showed binding activity to cytoplasmic or nuclear substances. Based on these results, the following hypothesis has been proposed. The Abs that had been originally produced against a membrane protein showed cross-reactivity against cytoplasmic or nuclear substances. In the present study we reported isolation of Abs that bound to both a membrane protein, CADM1, and a cytoplasmic protein, α-actinin-4. The method adopted in the present study could be generally applicable to isolation of Abs showing such dual specificity. Firstly, we constructed a huge human Ab library using various organs including naïve B-cell-rich organs such as bone marrow and umbilical cords. Then, we developed a comprehensive screening method for isolation of Abs that bound to cell surface antigens. Through extensive screenings with many kinds of cell we newly obtained a library composed of around 4000 independent clones that bind to membrane proteins. We screened this library with α-actinin-4 and succeeded in isolating two Abs. They bound to α-actinin-4 and a membrane protein CADM1. Furthermore, they are encoded by naïve heavy and light chain variable genes (V H & V L ). These results suggested that cross-reactive Abs to both a membrane protein and a cytoplasmic protein could be present in germline repertoire of Ab in humans. This methodology adopted in the present study could be applied to isolation of cross-reactive Abs possibly involved in autoimmune diseases. [ABSTRACT FROM AUTHOR]

Sensitization to human leukocyte antigens (HLA) in organ transplant patients causes graft rejection, according to the humoral theory of transplantation. Sensitization is almost ubiquitous as anti-HLA antibodies are found in almost all sera of transplant recipients. Advances in testing assays and amino acid sequencing of HLA along with computer software contributed further to the understanding of antibody-antigen reactivity. It is commonly understood that antibodies bind to HLA antigens. With current knowledge of epitopes, it is more accurate to describe that antibodies bind to their target epitopes on the surface of HLA molecular chains. Epitopes are present on a single HLA (private epitope) or shared by multiple antigens (public epitope). The phenomenon of cross-reactivity in HLA testing, often explained as cross-reactive groups (CREGs) of antigens with antibody, can be clearly explained now by public epitopes. Since 2006, we defined and reported 194 HLA class I unique epitopes, including 56 cryptic epitopes on dissociated HLA class I heavy chains, 83 HLA class II epitopes, 60 epitopes on HLA-DRB1, 15 epitopes on HLA-DQB1, 3 epitopes on HLA-DQA1, 5 epitopes on HLA-DPB1, and 7 MICA epitopes. In this paper, we provide a summary of our findings. [ABSTRACT FROM AUTHOR]

Characterization of leukocytes is an integral part of blood analysis and blood-based diagnostics. In the present paper, we combine lensless holographic imaging with antibody microarrays for rapid and multiparametric analysis of leukocytes from human blood. Monoclonal antibodies (Abs) specific for leukocyte surface antigens (CD4 and CD8) and cytokines (TNF-α, IFN-γ, IL-2) were printed in an array so as to juxtapose cell capture and cytokine detection antibody (Ab) spots. Integration of Ab microarrays into a microfluidic flow chamber (4 pL volume) followed by incubation with human blood resulted in capture of CD4 and CD8 T-cells on specific Ab spots. On-chip mitogenic activation of these cells induced release of cytokine molecules that were subsequently captured on neighboring anticytokine Ab spots. The binding of IL- 2, TNF-α, and IFN-γ molecules on their respective Ab spots was detected using horseradish peroxidase (HRP)-labeled anticytokine Abs and a visible color reagent. lensfree holographic imaging was then used to rapidly (∼4 s) enumerate CD4 and CD8 T-lymphocytes captured on Ab spots and to quantify the cytokine signal emanating from IL2, TNF-α, and IFN-γ spots on the same chip. To demonstrate the utility of our approach for infectious disease monitoring, blood samples of healthy volunteers and human immunodeficiency virus (HIV)-infected patients were analyzed to detennine the CD4/CD8 ratio, an important HIV/AIDS diagnostic marker. The ratio ob- tained bylensfree on-chip imaging of CD4 and CD8T-cells captured on Ab spots was in close agreement with conventional microscopy-based cell counting. The present paper, describing tandem use of Ab microarrays and Iensfree holographic imaging, paves the way for future development of miniature cytometly devices for multi-parametric blood analysis at the point of care or in a resource-limited setting. [ABSTRACT FROM AUTHOR]

Over the past couple of decades, antibody-drug conjugates (ADCs) have revolutionized the field of cancer chemotherapy. Unlike conventional treatments that damage healthy tissues upon dose escalation, ADCs utilize monoclonal antibodies (mAbs) to specifically bind tumour-associated target antigens and deliver a highly potent cytotoxic agent. The synergistic combination of mAbs conjugated to small-molecule chemotherapeutics, via a stable linker, has given rise to an extremely efficacious class of anti-cancer drugs with an already large and rapidly growing clinical pipeline. The primary objective of this paper is to review current knowledge and latest developments in the field of ADCs. Upon intravenous administration, ADCs bind to their target antigens and are internalized through receptor-mediated endocytosis. This facilitates the subsequent release of the cytotoxin, which eventually leads to apoptotic cell death of the cancer cell. The three components of ADCs (mAb, linker and cytotoxin) affect the efficacy and toxicity of the conjugate. Optimizing each one, while enhancing the functionality of the ADC as a whole, has been one of the major considerations of ADC design and development. In addition to these, the choice of clinically relevant targets and the position and number of linkages have also been the key determinants of ADC efficacy. The only marketed ADCs, brentuximab vedotin and trastuzumab emtansine (T-DM1), have demonstrated their use against both haematological and solid malignancies respectively. The success of future ADCs relies on improving target selection, increasing cytotoxin potency, developing innovative linkers and overcoming drug resistance. As more research is conducted to tackle these issues, ADCs are likely to become part of the future of targeted cancer therapeutics. [ABSTRACT FROM AUTHOR]

Ψ-3 is a monoclonal antibody that recognizes a 135,000 molecular weight structural component of maturing keratinocytes in psoriasis (the Ψ-3 antigen) but fails to bind to any constituent of keratinocytes in normal epidermis. This paper describes the occurrence of the Ψ-3 antigen in a variety of dermatopathologic conditions using immunoperoxidase (biotin-avidin-peroxidase) and immunofluorescence methods which show excellent concordance. In 35 of 36 specimens of psoriasis vulgaris, Ψ-3 antibody consistently immunolabels the cytoplasm of keratinocytes above the basal layer. At the edges of psoriatic plaques, Ψ-3 antibody staining extends for a variable distance into lesion-free epidermis. A similar pattern has been found in a certain number of other conditions described in the paper, including squamous cell carcinoma and condyloma acuminatum, but not Darier's disease basal cell carcinoma, nor lamellar ichthyosis. In all but one condition, the outermost or basal layer of cells is never stained. The only disease in which the lowermost cell layer is stained is a lichen planus-like lesion. The occurrence of Ψ-3 antigen cannot be correlated with any histologic feature of psoriasis such as acanthosis, loss of the granular layer, or hyperproliferation. The antigen appears to be a unique keratinocyte constituent which is expressed in certain pathologic conditions and which is not detected by any other histologic or immunophenotyping method. It is a potentially valuable addition to the panel of antibodies available for characterizing epithelial cells. [ABSTRACT FROM AUTHOR]

Since its inception in the mid-1980s of the 20th century testing for carbohydrate antigen 19-9 (CA 19-9) has raised expectation for an earlier diagnosis and accurate monitoring of several malignant diseases. After almost 30 years, the available evidences have confirmed the appropriateness and usefulness of determining CA 19-9 levels as a prognostic indicator and as a reliable tool for monitoring pancreatic and gastrointestinal cancer, but concerns have been raised about its applications in screening, which is actually not recommended, and in the diagnosis of malignancies, due to several interferences that limit the specificity and to the insufficient sensitivity of this marker. In this paper we aimed to review the basic concepts of CA 19-9 testing and its current applications, with a major focus on the most recent evidences dealing with assay interference, methods comparison and monitoring of malignant diseases. The prognostic value and monitoring recommendations for pancreatic, gastric and colorectal cancers are described in depth. [ABSTRACT FROM AUTHOR]

The Tn antigen (GalNAc α-O-Ser/Thr) is heterogeneously synthesized by a variety of tumors and contains an epitope defined by lectins and antibodies as a cluster of αGalNAc carbohydrates synthesized within a peptide sequence, which is rich in serine and/or threonine. The Tn antigen has been utilized as a target in vaccine experiments and also used as a biomarker for prognosis of different cancer forms. In this paper, we present a new monoclonal antibody, GOD3-2C4, with the clear hallmarks of an anti-Tn antibody. It was generated through somatic cell hybridization after immunization of a mouse with a tumor cell line and a Tn carrying mucin. The antibody recognizes synthetic Tn antigen and binds breast, colon, lung, ovarian and pancreas cancer. The GOD3-2C4 antibody has antibody-dependent cellular cytotoxicity activity against Jurkat cells in vitro, and for the first time, it can be shown that an anti-Tn antibody has a significant in vivo effect on a human cancer cell line grown as a xenograft in severe combined immunodeficiency mice. [ABSTRACT FROM AUTHOR]

Aim. To develop a method and obtain proof-of-principle for immunolymphoscintigraphy for identification of metastatic sentinel nodes. Methods. We selected one of four tumour-specific antibodies against human breast cancer and investigated (1), in immunedeficient (nude) mice with xenograft human breast cancer expressing the antigen if specific binding of the intratumorally injected, radioactively labelled, monoclonal antibody could be scintigraphically visualized, and (2) transportation to and retention in regional lymph nodes of the radioactively labelled antibody after subcutaneous injection in healthy rabbits. Results and Conclusion. Our paper suggests the theoretical possibility of amodel of dual isotope immuno-lymphoscintigraphy for noninvasive, preoperative, malignant sentinel node imaging. [ABSTRACT FROM AUTHOR]

Biologically active membrane proteins are difficult to isolate. Very often the isolated membrane proteins have low binding affinity or no biological integrity at all. Despite some success in isolation, one has to overcome the hurdles of obtaining sufficient quantity of the proteins and maintaining biological activity upon coating them on surfaces for developing an ELISA. Thus an alternative approach may be useful. The present study describes a quantification assay method for a therapeutic hmAb-1 (human monoclonal antibody-1) that recognizes a cell-surface protein employing an anti-ID (anti-idiotypic antibody) to hmAb-1 as a surrogate antigen in an immunoassay format using surface- plasmon-resonance technology. This assay is applicable for quantification of hmAb-1 in process streams, final drug-product quality control, as well as low-concentration drug substances in intravenous-solution bags. The surrogate nature of the anti-ID was confirmed by demonstrating that the anti-ID displaced the interaction between the hmAb-1 and its membrane antigen in a FACS titration test. The assay format involves first capturing hmAb-1 on the flow-cell surface, which then binds quantitatively to anti-ID in a mixture of increasing quantity of hmAb-1 in solution. An inverse dose–response relation between this anti-ID bound signal (or resonance units) and hmAb-1 concentration was established. The dose–response range of the calibration curve for hmAb-1 was between 20 and 300 ng/ml. The precision, accuracy and specificity of the assay are reported in the present paper. [ABSTRACT FROM AUTHOR]

Taenia solium oncosphere protein TSOL18 is the host-protective antigen against porcine cysticercosis. Little attention has been given to use it as target molecule in immunodiagnostic tests. The objective of this paper is to describe the immunodiagnostic potential of monoclonal antibodies (MoAbs) raised against conformational epitopes of TSOL18. Three murine IgG1 MoAbs (25D12C1, 21C2D2, 10H1F2) against three different conformational epitopes of TSOL18 were produced and evaluated with an inhibition enzyme-linked immunosorbent assay (i-ELISA) for the detection of anti-TSOL18 and anti-oncosphere antibodies. Serum samples from pigs immunized with TSOL18 inhibited the binding of the three MoAbs to TSOL18 antigen in i-ELISA. The highest inhibition of anti-TSOL18 antibodies in immunized pigs was observed with MoAb 25D12C1. Ten field sera (12.19%) from 82 non-vaccinated and non-infected pigs showed anti-oncosphere antibodies inhibiting the binding of MoAb 25D12C1. Anti-oncosphere antibodies in pigs experimentally infected with T. solium eggs inhibited the binding of MoAb 25D12C1 from 2 to 8 week-post infection. It is concluded that MoAb 25D12C1 has excellent immunodiagnostic potentials to detect anti-oncosphere antibodies in the intermediate hosts at early exposure to T. solium eggs. Further investigations on potential use of MoAb 25D12C1 in a capture antigen ELISA for the detection of post-oncospheral antigens in infected pigs cannot be overemphasized. [Display omitted] • We describe the potential usefulness of the monoclonal antibody 25D12C1 to TSOL18 protein. • Serum samples from pigs immunized with TSOL18 inhibited the binding of 25D12C1 in an inhibition enzyme-linked immunosorbent assay (i-ELISA) for the detection of anti-TSOL18 and anti-oncosphere antibodies. • Anti-oncosphere antibodies in pigs infected with T. solium eggs inhibited also the binding of 25D12C1. • It is concluded that MoAb i-ELISA using 25D12C1 has the potential to identify animals exposed to T. solium infection. [ABSTRACT FROM AUTHOR]

In this paper, two formats of enzyme-linked immunosorbent assays (ELISA) with the monoclonal antibody were adopted and compared to detect triazophos residue in an environmental water sample that employed a heterologous coating conjugate. The sensitivity and specificity of the two formats, indirect format (antigen-coated ELISA) and direct format (antibody-coated ELISA), were satisfied after most of the factors used to influence the analytical results of an immunoassay to triazophos were tested and optimised. Results showed that I50 and I20 were 2.54 and 0.54 ng/ml for the indirect format and 0.65 and 0.12 ng/ml for the direct format, respectively, without obvious cross-reactivity to other organophosphorus pesticide analogues tested. The mean recoveries of water samples spiked with triazophos were 115 and 103% for the indirect and direct format, respectively, and their mean coefficients of variation were 9.0 and 10.9%, respectively. [ABSTRACT FROM AUTHOR]

Immunoassays for detection of a class of closely related antigens, e.g., PCBs, have often been too specific (responding strongly to some members of the class and missing others) and no general method for adjusting the response has been described. In this paper, the difference in the response of a model immunoassay to different Kanechlors (Japanese commercial mixtures of PCBs, analogous to Aroclors in the United States) is reduced from 20. or 50-fold (depending on which antibody is used) to 3-fold when the antibodies are mixed at the proper ratio. A mathematical model based on competitive binding of two antibodies for up to four antigens has been developed and used to describe the assay performance and to predict optimum mix ratios for the antibodies used. The model (based on separate measurement of each antibody's effective Kd for each Kanechlor) provides an excellent fit to the measured mixed antibody assay response. The model is also successful in identifying cases where mixing monoclonal antibodies will not improve the response. It is thought the method described will have applicability in a variety of cases where the analytical goal is semiquantitative screening based on the total quantity of an unknown mixture of related compounds. [ABSTRACT FROM AUTHOR]

This paper describes the principle of a homogeneous indirect fluorescence quenching immunoassay that uses monoclonal antibodies. It is a carrier-free assay system that is performed completely in solution. The assay system was established for the determination of a low molecular weight substance (hapten), the herbicide diuron, used as a model analyte. A fluorescein–monuron conjugate together with a fluorescence-quenching monoclonal anti-fluorescein antibody and an anti-analyte antibody (here an anti-diuron/monuron monoclonal antibody) were used as central components of the assay. The fluorescein–monuron conjugate can be bound either by the anti-fluorescein monoclonal antibody or by the anti-diuron/monuron monoclonal antibody. Due to steric hindrance, binding of both antibodies to the conjugate was not possible at the same time. By selecting the antibody concentrations appropriately, a dynamic equilibrium can be established that permits the preferential binding of the anti-diuron/monuron antibody to the conjugate, which allows the fluorescein in the conjugate to fluoresce. This equilibrium can be easily altered by adding free analyte (diuron), which competes with the conjugate to bind to the anti-diuron/monuron antibody. A reduction of anti-diuron/monuron antibody binding to the conjugate results in an increase in the binding of the anti-fluorescein antibody, which leads to a decrease in the fluorescence of the conjugate. The fluorescence is therefore a direct indicator of the state of equilibrium of the system and thus also the presence of free unconjugated analyte. The determination of an analyte based on this test principle does not require any washing steps. After the test components are mixed, the dynamic equilibrium is rapidly reached and the results can be obtained in less than 5 min by measuring the fluorescence of the fluorescein. We used this test principle for the determination of diuron, which was demonstrated for concentrations of ∼5 nM. [ABSTRACT FROM AUTHOR]

Immunophenotyping, which utilizes panels of lineage-associated monoclonal antibodies to recognize clusters of differentiation (CD) antigens expressed on various leukocytes, plays a key role in the clinical diagnosis of acute leukemias. In this paper, a rapid, simple, and automatic immunophenotyping technique for acute leukemias has been initially proposed by incorporating immunomagnetic separation and quartz crystal microbalance (QCM) measurement. Core-shell paramagnetic microspheres of silica-coated ZnFe2O4 were newly fabricated following a W/O microemulsion route and further functionalized for anchoring separately CD antibodies of lineage-different leukocytes. The resultant immunomagnetic microspheres were introduced, in turn, to capture target leukocytes from the samples and were magnetically accumulated onto the protein A-modified QCM to be analyzed. The response characteristics of the developed QCM system for immunophenotyping various lineage-defined leukocytes were investigated in detail. Results indicate that this new technique can allow for easy and clear identification of acute leukocytes of lymphoid and myeloid origins as well as their subsets. It may also permit the quantitative determination of acute leukocytes with cell concentration down to ∼10³ cells mL-1. Moreover, the applicable feasibility of the QCM immunophenotyping method was validated through assessing a number of clinical specimens, which phenotypes are in acceptable agreement with those obtained by the immunoenzyme assay clinically used for this purpose. [ABSTRACT FROM AUTHOR]

Human metapneumovirus (hMPV) F protein promotes fusion of viral and cell membranes, and is thought to be a major antigenic determinant that mediates effective neutralization and protection against hMPV infection. In this paper, the development of two mouse monoclonal antibodies (MAbs) by immunization with hMPV-infected cells is described. Immunofluorescence assay (IFA) using hMPV F protein-expressing cells indicated that two MAbs, designated 1G3 and 9B10, recognized hMPV F protein. Both MAbs were found to be reactive to two groups of hMPV by an IFA using two groups of hMPV-infected cells. The 9B10 mAb had strong neutralizing activity against both groups of hMPV, while the 1G3 MAb had only weak neutralization activity. These results indicate that the hMPV F protein is a major antigenic determinant that mediates extensive cross-lineage neutralization and protection. Production of MAbs to the hMPV F protein is critical for development of diagnostic techniques, vaccine research, and studies on viral pathogenesis. [ABSTRACT FROM AUTHOR]

Given the key role 4-1BB plays in the stimulation of T cells, humanization of agonistic anti-human 4-1BB monoclonal antibody (mAb) may have important clinical applications. In this paper, we present the humanization of agonistic anti-human 4-1BB mAb, BBK-4, using a phage display library. We first prepared the combinatorial library by incorporating murine and human alternative at positions representing buried residues that might affect the structural integrity of the antigen binding site. Six humanized single chain Fv (scFv) fragments were selected from the combinatorial library expressing phage-displayed humanized scFv. They were found to retain the epitope specificity of the original mAb but had affinities of lower than 1/10 of the original. In spite of the lower affinity, the humanized scFv coated on the surface expanded human peripheral blood mononuclear cells (PBMCs) in MLR similarly to the original mAb in the presence of anti-CD3 mAb. These results suggest that humanized anti-human 4-1BB scFvs can be used as a valuable reagent for clinical application. [Copyright &y& Elsevier]

One hundred and forty five Mabs against RH antigens were tested. In this paper, we chose to detail reactivity of MoAbs directed against variant RBCs of the CNRGS collection for which we studied the molecular background. Because we developed procedures to identify variants of the RhD, RhC, RhE and Rhe antigens, we were especially interested in finding new monoclonal antibodies that could help us to characterize more accurately these variants. Therefore, we drew parallels between our procedures and results obtained with the 2001 workshop antibodies. [Copyright &y& Elsevier]

A panel of monoclonal antibodies (mAb) was developed by the fusion of Sp2/0 myeloma cells and spleen cells from mice immunized with peripheral blood mononuclear cells (PMNC) or T cells from NIH swine leucocyte antigen (SLA) inbred miniature swine. Twenty stable hybridoma clones were isolated that secreted mAb that reacted with swine PMNC, as determined by an enzyme-linked immunosorbent assay (ELISA). The binding profile to swine PMNC and the ability to fix complement of these mAb were investigated by flow cytometric analyses. The molecular weights of the antigens recognized by six of the mAb were determined by immunoprecipitation of 125I-surface-labelled PMNC, followed by SDS-PAGE under reducing conditions. The most interesting mAb, 7-34-1 (IgG2a), precipitated a putative MUC class I molecule composed of a 50,000 MW heavy chain and a 12,000 MW light chain (β2m). This is the third SLA class I-reactive monoclonal antibody to be described for swine. Properties of the mAb described in this paper, mAb 7-34-1, are different from the two other SLA class I-specific mAb that have been described elsewhere in the literature (mAb 74-11-10 and mAb FF85). M onoclonal antibody 7-34-1 recognized class I antigens of SLA haplotypes a, c and din an equivalent manner. This mAb should be especially useful as a general anti- SLA class I reagent for experiments on NIH miniature swine. [ABSTRACT FROM AUTHOR]

Reagents for the identification of rabbit cell markers have been developed at a relatively slow rate. In this paper, rabbit cells are being characterized by polyclonal antibodies against a Tall antigen (RTLA), a B-cell antigen (RABELA) and an analogue of murine Ia antigen. A number of monoclonal antibodies, specific for lymphocytes and/or bone marrow and/or polymorphonuclear leucocytes, have been used for the analysis of cells with identifiable membrane antigens. Populations that have cells with two of the above antigens in the membranes were identified. To these ends, complement-mediated cell kill by antisera alone and in mixtures was employed. [ABSTRACT FROM AUTHOR]

In this paper, we describe the activity of conjugates constituted of monoclonal antibodies chemically coupled to ricin and the ricin A-chain-like toxin gelonin. Several antibody-toxin conjugates (immunotoxins) were assayed against a Thy 1.2+ and Lyt 2.2+ T-cell line. Anti-Thy 1.2-gelonin and anti-Lyt 2.2-ricin immunotoxins (IT) had a good cytotoxic activity against target cells, whereas anti-Lyt 2.2-gelonin showed weak or no cytotoxicity. An anti-Lyt 2.2-gelonin IT displayed detectable cytotoxicity only when cells were pretreated with ammonium chloride. IT binding activity was very similar for anti-Thy 1.2 and anti-Lyt 2.2 IT, and surface antigen density was of the same order of magnitude for Thy 1.2 and Lyt 2.2 antigens. Our results suggest that intrinsic properties of the surface target antigen are able to influence the IT cytotoxic efficacy. [ABSTRACT FROM AUTHOR]

The results presented in this paper demonstrate that a mouse IgM monoclonal antibody (T-80) recognizes an antigen on cells of the T-lymphocyte lineage of sheep. However, this antibody does not identify all T cells, as 10-20% of thymocytes and some peripheral-blood T cells are negative. T-80- thymocytes reside in the medulla. The majority of cortical thymocytes are T-80+ and classified as dull cells on the basis of antigen density per cell as measured by flow microfluorometry. In contrast, T-80+ cells in the periphery can be categorized into two populations, i.e., dull cells and bright cells. Suggestive evidence was obtained that bright T-80+ cells are fast recirculating T cells, whereas dull ceils are sessile or less easily mobilizable T cells in the periphery. In foetal environment, over 90% of thymocytes and approximately 5% of spleen cells are T-80+ at 54 days of gestation (gestation period = 150 days), which may indicate that T-cell emigration from the thymus commences well before mid-gestation in sheep. [ABSTRACT FROM AUTHOR]

CD34 is a cell surface glycoprotein expressed by hematopoietic progenitors and endothelial cells. It is widely used in the clinic for isolation of human hematopoietic stem cells. In recent years large animals are gaining increasing importance in biomedical research for the study and therapy of human diseases. Sheep has proved to be an useful experimental model for preclinical trials in transplantation procedures. Unfortunately, the lack of specie-specific monoclonal antibodies (MABS) recognizing hemopoietic progenitor cells hampers the use of this animal in experimental hematology. The aim of this paper was to determine whether commercial monoclonal antibodies specific for human CD34 molecule could cross-react with hematopoietic progenitor cells (HPC) present in sheep umbilical cord blood (UCB). Six antihuman CD34 MABS, recognizing the three different epitope classes, were tested in flow cytometry on purified mononuclear cells (MNC) isolated from cord blood of both species. None of the MABS used in this trial seemed to be able to identify HPC from sheep UCB. These data suggest that the panel of monoclonal antibodies used for cross reactivity detection has to be expanded with recently produced reagents. Further studies should be directed towards the production of ovine specific anti CD34 MABS. [ABSTRACT FROM AUTHOR]

Photochemical internalization (PCI) is a further development of photodynamic therapy (PDT). In this report, we describe PCI as a potential tool for cellular internalization of chemotherapeutic agents or antigens and systematically review the ongoing research. Eighteen published papers described the pre-clinical and clinical developments of PCI-mediated delivery of chemotherapeutic agents or antigens. The studies were screened against pre-defined eligibility criteria. Pre-clinical studies suggest that PCI can be effectively used to deliver chemotherapeutic agents to the cytosol of tumor cells and, thereby, improve treatment efficacy. One Phase-I clinical trial has been conducted, and it demonstrated that PCI-mediated bleomycin treatment was safe and identified tolerable doses of the photosensitizer disulfonated tetraphenyl chlorin (TPCS2a). Likewise, PCI was pre-clinically shown to mediate major histocompatibility complex (MHC) class I antigen presentation and generation of tumor-specific cytotoxic CD8+ T-lymphocytes (CTL) and cancer remission. A first clinical Phase I trial with the photosensitizer TPCS2a combined with human papilloma virus antigen (HPV) was recently completed and results are expected in 2020. Hence, photosensitizers and light can be used to mediate cytosolic delivery of endocytosed chemotherapeutics or antigens. While the therapeutic potential in cancer has been clearly demonstrated pre-clinically, further clinical trials are needed to reveal the true translational potential of PCI in humans. [ABSTRACT FROM AUTHOR]

Previously, we successfully prepared a monoclonal antibody (mAb) named 2E4, that directly recognizes the major envelope protein B2L of the orf virus (ORFV), but there is little information about its epitope. Here, we meticulously mapped the 2E4 epitope through combinatorial programs and identified the functional binding domain and a key amino acid residue. Briefly, the simulated epitope peptide closely resembles 84VDVQSKDKDADELR97 located at the N-terminus of B2L, strongly suggesting that the epitope is conformationally or spatially structure-dependent. Subsequently, we combined these findings with the results from the antigenicity prediction of B2L to design three truncated fragments of B2L (F1, F2 and F3) selected using 2E4, and only the F1 fragment was found to be eligible for the advanced stage. Alanine-scanning mutagenesis suggested that the D94 residue is structurally crucial for the 2E4 epitope. The other participating residues, including K61, E62, and D92, together with D94 were responsible for enabling 2E4 binding and served as factors that synergistically enabled binding to the whole 2E4 epitope. In this paper, we describe, for the first time, the architecture of an ORFV conformational epitope, and it is also expected that mAb 2E4 and its epitope can be used for applications relating to orf control. [ABSTRACT FROM AUTHOR]