Fragment Antigen Research Articles

A Thermally Reformable Protein Polymer

Summary Complex biomaterials easily formed by self-assembling proteins could transform regenerative medicine and 3D cell culture. However, although readily achieved by short peptides, materials assembled from proteins with a defined tertiary structure are still rare. The bacterial fimbrial protein, capsular antigen fragment 1 (Caf1), forms long polymers of subunits linked by kinetically stable non-covalent interactions, which can be further chemically crosslinked into a variety of hydrogels. We report here that the complete thermal dissociation of Caf1 polymers or hydrogels into individual subunits is fully reversible with high yield. This simple feature endows the Caf1 polymer with outstanding synthetic and materials possibilities and, to demonstrate, we describe the in vitro assembly of complex bioactive copolymers and provide example applications of meltable protein hydrogels. We anticipate that the highly efficient and reversible assembly of these multifunctional polymeric proteins will enhance significantly the development of proteinaceous biomaterials for clinical and industrial applications.

Ultrasensitive label-free detection for lung cancer CYFRA 21-1 DNA based on ring-opening polymerization

Cytokeratin fragment antigen 21-1 (CYFRA 21-1) DNA is perceived as sensitive tumor marker for the diagnosis of non-small cell lung cancer and other tumor. Herein, linear chain poly(ε-caprolactone) (PCL) synthesized by ring-opening polymerization is applied to ultrasensitive label-free electrochemical impedance detection system for CYFRA 21-1 DNA. First, thiolated peptide nucleic acid (PNA) is self-assembled into the Au electrode surface through the formation of Au–S bonds, allowing the PNA to act as biomolecular probe and form PNA/DNA heteroduplex with the target DNA via specific hybridization. Then, PCL is conjugated to the immobilized DNA on the electrode via “carboxylate–Zr4+–phosphate” bridges. Finally, the electrochemical response of modified PNA/DNA/Zr4+/PCL electrode is determined by electrochemical impedance method to quantify of CYFRA 21-1 DNA. Under optimal conditions, this method exhibits highly sensitivity with a broad linear range (0.1 fM – 1 nM) (R2 = 0.995) and the limit of detection (LOD) is as low as 10.73 aM, which is equivalent to just 64 molecules in a 10 μL sample. What's more, the high selectivity, good anti-interference, label-free operation, and real-time monitoring in complex samples of the proposed strategy demonstrate its broad application for the early diagnosis and clinical monitoring.

Isolation of Common Light Chain Antibodies from Immunized Chickens Using Yeast Biopanning and Fluorescence-Activated Cell Sorting.

The phylogenetic distance between chickens and humans accounts for a strong immune response and a broader epitope coverage compared to rodent immunization approaches. Here the authors report the isolation of common light chain (cLC)-based chicken monoclonal antibodies from an anti-epidermal growth factor receptor (EGFR) immune library utilizing yeast surface display in combination with yeast biopanning and fluorescence-activated cell sorting (FACS). For the selection of high-affinity antibodies, a yeast cell library presenting cLC-comprising fragment antigen binding (Fab) fragments is panned against hEGFR-overexpressing A431 cells. The resulting cell-cell-complexes are sorted by FACS resulting in gradual enrichment of EGFR-binding Fabs in three sorting rounds. The isolated antibodies share the same light chain and show high specificity for EGFR, resulting in selective binding to A431 cells with notable EC50 values. All identified antibodies show very good aggregation propensity profiles and thermostabilities. Additionally, epitope binning demonstrates that these cLC antibodies cover a broad epitope space. Isolation of antibodies from immunized chickens by yeast cell biopanning makes an addition to the repertoire of methods for antibody library screening, paving the way for the generation of cLC-based bispecific antibodies against native mammalian receptors.

CYFRA 21-1 in patients with suspected cancer: evaluation of an optimal cutoff to assess the diagnostic efficacy and prognostic value.

Chosen cutoff for cytokeratin 19 fragment antigen (CYFRA 21-1) as a tumor biomarker considerably influences its diagnostic and prognostic usefulness. The aim of the present study is to determine an optimal cutoff value for diagnostic validity of CYFRA 21-1 by Lumipulse ® technology in patients with suspected cancer and also to determine if CYFRA 21-1 levels provide prognostic value. A consecutive 284 patients suggestive of malignant disease from six hospitals of Madrid were enrolled in a retrospective design. Optimal CYFRA 21-1 cutoff value was obtained by receiver operating characteristic curve and Youden test. The diagnostic validity was evaluated according to sensitivity, specificity, predictive values and likelihood ratios. The prognostic value of CYFRA 21-1 was checked using multiple logistic regression. Thirty-two diagnostic cancers were confirmed. The most optimal cutoff was 3.15ng/mL. This cutoff showed a better specificity 93.63% (95% confidence interval [CI], 89.66-96.16), positive predictive value 60.98% (95% CI, 44.54-75.38) and positive likelihood ratio 12.65 (95% CI, 7.64-20.95) than the cutoff recommended by Fujirebio® (1.8ng/mL) (specificity: 73.71% [95% CI, 67.72-78.95], positive predictive value: 29.79% [95% CI, 21.02-40.23] and positive likelihood ratio 3.43 [95% CI, 2.71-4.35]), improving the current diagnostic accuracy. In multivariate analysis, elevated levels of CYFRA 21-1 (>3.15ng/mL) was confirmed as an unfavorable prognostic factor. The best cutoff for CYFRA 21-1 obtained was 3.15ng/mL in patients with suspected cancer. This new cutoff decreases the false positive rate and improves the diagnostic efficacy of CYFRA 21-1 as a tumor marker as well as its association with death events.

Clinical significance of serum anti-granulocyte\u2013macrophage colony-stimulating factor autoantibodies in patients with sarcoidosis and hypersensitivity pneumonitis

BackgroundAnti-granulocyte–macrophage colony-stimulating factor autoantibody (GMAb) has been recognized as a diagnostic biomarker for autoimmune pulmonary alveolar proteinosis (aPAP). The aims of this study were to know the incidence of increased level of serum GMAb in granulomatous lung diseases (sarcoidosis and hypersensitivity pneumonitis [HP]) and to clarify the role of GMAb. Consecutive individuals diagnosed with sarcoidosis (n = 92) and HP (n = 45) at National Hospital Organization Kinki-Chuo Chest Medical Center were retrospectively analyzed. We measured serum GMAb levels at the diagnosis. Cut-off values of GMAb discriminating aPAP (n = 110) from healthy controls (n = 31) were determined by receiver operating characteristic (ROC) curve analysis. We compared the clinical features of sarcoidosis and HP patients with GMAb levels above the cut-off value (“Elevated-GMAb”) with those of patients whose GMAb levels below the cut-off value (“Low-GMAb”). Radiological and pathological findings in elevated-GMAb patients were re-evaluated to elucidate the role of GMAb in granulomatous lung diseases.ResultsAnalysis of ROC indicated a sensitivity and specificity of 100% at GMAb level of 3.33 μg/mL for discriminating aPAP from healthy controls (area under curve = 1.000, p < 0.0001). The percentages of elevated-GMAb sarcoidosis and HP patients were 5.4% (n = 5) and 11.1% (n = 5), respectively. The number of comorbid sarcoidosis and HP patients with aPAP was two and one, respectively. Elevated-GMAb sarcoidosis patients presented with significantly higher serum levels of Krebs von den Lungen (KL)-6, surfactant protein-D (SP-D), lactate dehydrogenase, and the requirement of systemic corticosteroid therapy. Elevated-GMAb HP patients demonstrated older age, higher serum KL-6, SP-D, carcinoembryonic antigen, and cytokeratin fragment 21-1 levels, and a higher percentage of lymphocytes in bronchoalveolar lavage than low-GMAb patients. A subset of patients presented with radiological and pathological findings characteristic of aPAP.ConclusionsWe demonstrated the percentage of elevated-GMAb sarcoidosis and HP patients who presented with several features suggestive of aPAP. Elevated-GMAb sarcoidosis and HP patients without definitive aPAP diagnosis may have subclinical or early-stage aPAP and may not necessarily indicate false positives. Upon diagnosis of sarcoidosis or HP, measurement of GMAb may be useful in detecting possible comorbidity of subclinical or early-onset aPAP.

Solubility, Stability, and Avidity of Recombinant Antibody Fragments Expressed in Microorganisms.

Solubility of recombinant proteins (i.e., the extent of soluble versus insoluble expression in heterogeneous hosts) is the first checkpoint criterion for determining recombinant protein quality. However, even soluble proteins often fail to represent functional activity because of the involvement of non-functional, misfolded, soluble aggregates, which compromise recombinant protein quality. Therefore, screening of solubility and folding competence is crucial for improving the quality of recombinant proteins, especially for therapeutic applications. The issue is often highlighted especially in bacterial recombinant hosts, since bacterial cytoplasm does not provide an optimal environment for the folding of target proteins of mammalian origin. Antibody fragments, such as single-chain variable fragment (scFv), single-chain antibody (scAb), and fragment antigen binding (Fab), have been utilized for numerous applications such as diagnostics, research reagents, or therapeutics. Antibody fragments can be efficiently expressed in microorganisms so that they offer several advantages for diagnostic applications such as low cost and high yield. However, scFv and scAb fragments have generally lower stability to thermal stress than full-length antibodies, necessitating a judicious combination of designer antibodies, and bacterial hosts harnessed with robust chaperone function. In this review, we discuss efforts on not only the production of antibodies or antibody fragments in microorganisms but also scFv stabilization via (i) directed evolution of variants with increased stability using display systems, (ii) stabilization of the interface between variable regions of heavy (VH) and light (VL) chains through the introduction of a non-native covalent bond between the two chains, (iii) rational engineering of VH-VL pair, based on the structure, and (iv) computational approaches. We also review recent advances in stability design, increase in avidity by multimerization, and maintaining the functional competence of chimeric proteins prompted by various types of chaperones.

Sheathless CE‐MS as a tool for monitoring exchange efficiency and stability of bispecific antibodies

Bispecific monoclonal antibodies (BsAbs) are receiving great attention due to their extensive benefits as biopharmaceuticals and their involvement in IgG4 mediated autoimmune diseases. While the production of BsAbs is getting more accessible, their analytical characterization remains challenging. We explored the potential of sheathless CE-MS for monitoring exchange efficiency and stability of in-house produced bispecific antibodies. Two IgG4 bispecific antibodies with different molecular characteristics were prepared using controlled Fragment antigen binding (Fab)-arm exchange. Separation of BsAbs from their parent monospecific antibodies was achieved using a polyethyleniimine (PEI)-coated capillary and acidic background electrolytes permitting reliable assessment of the exchange efficiency. This was especially valuable for a Fab-glycosylated BsAb where the high glycan heterogeneity resulted in an overlap of masses with the monospecific parent antibody, hindering their discrimination by MS only. The method showed also good capabilities to monitor the stability of the generated BsAbs under different storage conditions. The levels of degradation products were different for the studied antibodies indicating pronounced differences in stability. Overall, the proposed method represents a useful analytical tool for exchange efficiency and stability studies of bispecific antibodies.

A phage‐displayed single‐chain Fab library optimized for rapid production of single‐chain IgGs

Phage-displayed synthetic antibody (Ab) repertoires have become a major source of affinity reagents for basic and clinical research. Specific Abs identified from such libraries are often screened as fragments antigen binding (Fabs) produced in bacteria, and those with desired biochemical characteristics are reformatted for production as full-length immunoglobulin G (IgG) in mammalian cells. The conversion of Fabs to IgGs is a cumbersome and often rate-limiting step in the development of Abs. Moreover, biochemical properties required for lead IgG development are not always shared by the Fabs, and these issues are not uncovered until a significant effort has been spent on Abs that ultimately will not be useful. Thus, there is a need for simple and rapid techniques to convert phage-displayed Fabs to IgGs at an early stage of the Ab screening process. We report the generation of a highly diverse phage-displayed synthetic single-chain Fab (scFab) library, in which the light and heavy chains were tethered with an optimized linker. Following selection, pools of scFabs were converted to single-chain IgGs (scIgGs) en masse, enabling facile screening of hundreds of phage-derived scIgGs. We show that this approach can be used to rapidly screen for and select scIgGs that target cell-surface receptors, and scIgGs behave the same as conventional IgGs.

Expected immune recognition of COVID-19 virus by memory from earlier infections with common coronaviruses in a large part of the world population.

SARS-CoV-2 is the coronavirus agent of the COVID-19 pandemic causing high mortalities. In contrast, the widely spread human coronaviruses OC43, HKU1, 229E, and NL63 tend to cause only mild symptoms. The present study shows, by in silico analysis, that these common human viruses are expected to induce immune memory against SARS-CoV-2 by sharing protein fragments (antigen epitopes) for presentation to the immune system by MHC class I. A list of such epitopes is provided. The number of these epitopes and the prevalence of the common coronaviruses suggest that a large part of the world population has some degree of specific immunity against SARS-CoV-2 already, even without having been infected by that virus. For inducing protection, booster vaccinations enhancing existing immunity are less demanding than primary vaccinations against new antigens. Therefore, for the discussion on vaccination strategies against COVID-19, the available immune memory against related viruses should be part of the consideration.

Ultrasensitive detection of CYFRA 21-1 DNA via SI-RAFT based in-situ metallization signal amplification

Cytokeratin fragment antigen 21-1 (CYFRA 21-1) DNA is a significant biomarker with relation to non-small cell lung cancer. Here, we described an ultrasensitive electrochemical biosensor for detection of CYFRA 21-1 DNA (target DNA, tDNA) via surface-initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization-based DNA metallization signal amplification strategy. Specifically, 5′terminal modified thiol peptide nucleic acid (PNA) probes are immobilized on the gold electrode surface (by Au-S selfassembly) for the identification of specific tDNA sequences. After hybridization, the 4-cyano-4-(phenylcarbonothioylthio) pentanoic acid (CPAD) is tethered to the PNA/DNA duplexes by means of the recognized phosphate-Zr4+-carboxylate chemistry. Subsequently, in the situation of C3H4O as the monomer, SI-RAFT polymerization can bring numerous aldehyde groups sites for the subsequent silver mirror reaction. The acrolein-polymers act as reductant to reduce Ag+ into Ag0, and then the silver particles are deposited on the polymer skeleton, which significantly amplifies the electrochemical signal. Under optimal conditions, the designed sensor for tDNA detection show a wide linear range from 100 aM to 1 nM, and the detection limit is as low as 0.89 aM. Moreover, the proposed biosensor exhibits prominent applicability for analysis of tDNA in serum samples and high selectivity for different mismatched oligonucleotide fragments. Given the proposed biosensor without extra natural enzyme or bio-labels, this method has enormous potential in bioanalysis.

Dynamics of Serum Tumor Markers Can Serve as a Prognostic Biomarker for Chinese Advanced Non-small Cell Lung Cancer Patients Treated With Immune Checkpoint Inhibitors.

Background: Serum tumor markers carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), cytokeratin 19 fragment (CYFRA21-1) and squamous-cell carcinoma-related antigen (SCC-Ag) are routinely used for monitoring the response to chemotherapy or targeted therapy in advanced-stage non-small cell lung cancer (NSCLC), however their role in immunotherapy remains unclear. The aim of this study was to investigate whether dynamics of these serum markers were associated with the efficacy and prognosis of Chinese late-stage NSCLC patients treated with programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) inhibitors.Methods: We initiated a longitudinal prospective study on advanced NSCLC patients treated with PD-1/PD-L1 inhibitors in Chinese PLA general hospital (Beijing, China). Blood samples of baseline and after 6 weeks' treatment were collected. CT scan were used by all patients to evaluate treatment efficacy according to RECIST 1.1. Serum tumor markers levels were measured with an electrochemical luminescence for SCC-Ag and with a chemiluminescent microparticle immunoassay for serum CEA, CA125, and CYFRA21-1. At least 20% decreases of the biomarkers from baseline were considered as meaningful improvements after 6 weeks of treatment with immune checkpoint inhibitors (ICIs). Optimization-based method was used to balance baseline covariates between different groups. Associations between serum tumor biomarker improvements and objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were analyzed.Results: A total of 308 Chinese patients with advanced NSCLC were enrolled in the study. After balancing baseline covariates, patients with meaningful improvements in <2 out of 4 biomarkers (CEA, CA125, CYFRA21-1, and SCC-Ag) was ended up with lower ORR (0.08 vs. 0.35, p < 0.001), shorten PFS (median: 5.4 vs. 12.5 months, p < 0.001), and OS (median: 11.7 vs. 25.6 months, p < 0.001) in the total population. Subgroup analysis of patients with adenocarcinoma revealed that patients with meaningful improvements in <2 out of 4 biomarkers had significant lower ORR (0.06 vs. 0.36, p < 0.001), shorten PFS (median: 4.1 vs. 11.9 months, p < 0.001), and OS (median: 11.9 vs. 24.2 months, p < 0.001). So as in patients with squamous cell carcinoma, meaningful improvements in at least 2 out of 4 biomarkers were linked to better ORR (0.42 vs. 0.08, p = 0.014), longer PFS (median: 13.1 vs. 5.6 months, p = 0.001), and OS (median: 25.6 vs. 10.9 months, p = 0.06).Conclusions: The dynamic change of CEA, CA125, CYFRA21-1, and SCC-Ag from baseline have prognostic value for late-stage NSCLC patients treated with PD-1/PD-L1 inhibitors. Decrease of associated biomarkers serum levels were associated with favorable clinical outcomes.

A phase Ib, open-label, dose-escalation trial of naptumomab estafenatox (Nap) in combination with durvalumab (MEDI4736) in subjects with selected advanced or metastatic solid tumors.

TPS3160 Background: Immunotherapy with the anti-PD-(L)1 checkpoint inhibitors (CPIs) has been largely ineffective in so-called non-immunogenic “cold tumors”. Facilitating T cell infiltration is necessary to invoke an immune response which may be augmented or complemented by the activity of CPIs like durvalumab. Selective T cell Redirection Proteins (STRs) are fusion proteins that consist of genetically engineered Superantigen (Sag) linked to Fragment antigen binding (Fab) moieties directed to tumor-associated antigens. Nap is a first in class STR compound, recognizing the tumor-associated oncofetal antigen 5T4, whereas the SAg moiety selectively engages the T cell receptor β variable (TRBV) 7-9. Nap has been shown to induce specific T cells expansion, activation and infiltration into the tumor in pre-clinical and clinical studies. Pre-clinical data demonstrated that the combination of STR with CPI may lead to long term durable responses not possible in most patients receiving single agent CPI therapy and suggests that combining CPIs with STR may be a promising therapeutic strategy for patients with solid tumors. Methods: Patients will be treated with the combination of Nap and durvalumab using a flat dose of durvalumab (1120 mg) and the 3+3 design for Nap dose escalation (2, 5, 10, 15 and 20 mcg/kg). The MTD of Nap for the combination treatment will be established based on DLTs occurring during the first treatment cycle. The dose escalation part will be followed by MTD expansion cohort in which 10–15 patients will be treated with MTD of Nap and 1120 mg durvalumab (Clinical trial registry number NCT03983954). Major eligibility criteria include patients with pretreated advanced or metastatic, 5T4 expressing solid tumors, including patients previously progressed on CPI therapy. As of January 2020, enrollment to dose levels 2, 5 and 10 mcg/kg has been completed without DLT, enrollment to dose level 15 mcg/kg will start on February 2020. Clinical trial information: NCT03983954 .

Clinical Value of Tumor Marker Index Based on Preoperative CYFRA 21-1 and SCC-Ag in the Evaluation of Prognosis and Treatment Effectiveness in Patients with Esophageal Squamous Cell Carcinoma.

BackgroundThis study aimed to investigate the prognostic value of tumor marker index (TMI) based on preoperative cytokeratin 19 fragment (CYFRA 21–1) and squamous cell carcinoma antigen (SCC-Ag) and the relationship between preoperative TMI and treatment effectiveness of postoperative adjuvant chemotherapy for patients with esophageal squamous cell carcinoma (ESCC).Patients and MethodsBetween January 2009 and December 2014, a total of 267 patients with ESCC who underwent radical resection were retrospectively enrolled. The TMI was defined as the geometric mean of normalized CYFRA 21–1 and SCC-Ag levels. The clinical and prognostic values of TMI were determined using univariate and multivariate survival analyses.ResultsPreoperative TMI level was associated with age, tumor size, pT stage, pN stage, and CYFRA 21–1, SCC-Ag, neutrophil-lymphocyte ratio (NLR), and platelet-lymphocyte ratio (PLR) levels. The 5-year overall survival rate of patients with high TMI was significantly lower than that of patients with low TMI (P < 0.001). Univariate and multivariate analyses revealed that TMI (P = 0.031) was an independent prognostic factor. Patients with ESCC with high TMI level who underwent surgery combined with postoperative chemotherapy had a significantly better prognosis than those who underwent surgery alone (P = 0.015). However, no significant difference was observed in patients with low TMI level (P = 0.682).ConclusionTMI as a prognostic indicator of ESCC is superior to CYFRA 21–1 and SCC-Ag. The TMI might be useful in predicting the therapeutic effectiveness of postoperative chemotherapy and selecting patients who may benefit from postoperative chemotherapy.

Phage display technology and molecular simulation combination to characterize anti-Opisthorchis viverrini antibodies

Abstract KKU505 hybridoma cell was used to produce monoclonal anti-Opisthrochis viverrini (OV) antibody. Unfortunately, hybridoma technology has many problems with instability for antibody production. Many studies have shown the possibility of developing a monoclonal antibody production using the antibody phage display. This paper presents antibody phage display technology for producing the phage display of the KKU505 Fab fragment and characterization using experiments and molecular simulations. The characterization was successfully displayed on KKU505 Fab fragment phage particle using experimental means integrated with the molecular simulation. For the experiments, indirect ELISA was shown to be specific to the OV antigen in this KKU505 Fab fragment on the phage particle. Immunohistochemistry has been shown to have a localization and reaction pattern of phage presenting KKU505 Fab fragment with biliary mouse tissue infected with O. viverrini. In particular, the significance of the antibody-antigen dock was studied in order to gain a better understanding of the mechanisms underlying the KKU505 mAb and of the crude OV antigen interaction by Western blot. All results showed that the fragment KKU505 Fab displayed on the phage particle has specific to the OV crude antigens. This study has shown that high potential phage displays technology shows monoclonal antibody production development. We have shown how the interactions of the KKU505 Fab fragment and OV antigen are evaluated in a successful application of experiment and molecular simulation. This fragment of the KKU505 Fab display on the particle is being developed to be used as a tool for diagnosing human opisthorchiasis.

Expected immune recognition of COVID-19 virus by memory from earlier infections with common coronaviruses in a large part of the world population.

SARS-CoV-2 is the coronavirus agent of the COVID-19 pandemic causing high mortalities. In contrast, the widely spread human coronaviruses OC43, HKU1, 229E, and NL63 tend to cause only mild symptoms. The present study shows, by in silico analysis, that these common human viruses are expected to induce immune memory against SARS-CoV-2 by sharing protein fragments (antigen epitopes) for presentation to the immune system by MHC class I. A list of such epitopes is provided. The number of these epitopes and the prevalence of the common coronaviruses suggest that a large part of the world population has some degree of specific immunity against SARS-CoV-2 already, even without having been infected by that virus. For inducing protection, booster vaccinations enhancing existing immunity are less demanding than primary vaccinations against new antigens. Therefore, for the discussion on vaccination strategies against COVID-19, the available immune memory against related viruses should be part of the consideration.

Latency reversal agents modulate HIV antigen processing and presentation to CD8 T cells.

Latency reversal agents (LRA) variably induce HIV re-expression in CD4 T cells but reservoirs are not cleared. Whether HIV epitope presentation is similar between latency reversal and initial infection of CD4 T cells is unknown yet crucial to define immune responses able to detect HIV-infected CD4 T cells after latency reversal. HIV peptides displayed by MHC comes from the intracellular degradation of proteins by proteasomes and post-proteasomal peptidases but the impact of LRAs on antigen processing is not known. Here we show that HDAC inhibitors (HDCAi) reduced cytosolic proteolytic activities while PKC agonists (PKCa) increased them to a lesser extent than that induced by TCR activation. During the cytosolic degradation of long HIV peptides in LRA-treated CD4 T cells extracts, HDACi and PKCa modulated degradation patterns of peptides and altered the production of HIV epitopes in often opposite ways. Beyond known HIV epitopes, HDACi narrowed the coverage of HIV antigenic fragments by 8-11aa degradation peptides while PKCa broadened it. LRAs altered HIV infection kinetics and modulated CD8 T cell activation in an epitope- and time-dependent manner. Interestingly the efficiency of endogenous epitope processing and presentation to CD8 T cells was increased by PKCa Ingenol at early time points despite low levels of antigens. LRA-induced modulations of antigen processing should be considered and exploited to enhance and broaden HIV peptide presentation by CD4 T cells and to improve immune recognition after latency reversal. This property of LRAs, if confirmed with other antigens, might be exploited to improve immune detection of diseased cells beyond HIV.

Attenuated porcine-derived type 2 bovine viral diarrhea virus as vector stably expressing viral gene

Infectious bovine viral diarrhea virus (BVDV) cDNA clones have been used for the expression of classical swine fever virus (CSFV) genes for immune prevention and control. However, can it be used for the expression of an allogenetic fragment? To answer this question, a BVDV chimeric virus expressing the spike (S) antigen fragment of porcine epidemic diarrhea virus (PEDV) was constructed. Antigen S499-602 was inserted into pig-derived BVDV-2 infectious cDNA clone pASH28 in tandem by overlapping PCR, located between the seventh and eighth amino acids at the N-terminus of the capsid (C) protein of BVDV. Indirect immunofluorescence assay confirmed that the chimeric virus vASH-dS312 containing double S499-602 sequences was successfully assembled, which could react with the monoclonal antibody (MAb) against BVDV E2 and PEDV S proteins. Further western blot analysis confirmed that the exogenous S499-602 double protein could be stably expressed. Next, the chimeric virus vASH-dS312 was administered to BALB/C mice either orally or by intramuscular injection. The immunized mice were healthy and showed no signs of toxicity. IgG against BVDV and PEDV antibodies could be detected in the mice administered vASH-dS312 by intramuscular injection, which had neutralization activity against BVDV and PEDV. Thus, this study reported a new insertion site in the BVDV infectious cDNA clone that could successfully express an allogenetic antigen.

Specificity of human natural antibodies referred to as anti-Tn

To understand the role of human natural IgM known as antibodies against the carbohydrate epitope Tn, the antibodies were isolated using GalNAcα−Sepharose affinity chromatography, and their specificity was profiled using microarrays (a glycan array printed with oligosaccharides and bacterial polysaccharides, as well as a glycopeptide array), flow cytometry, and inhibition ELISA. The antibodies bound a restricted number of GalNAcα-terminated oligosaccharides better than the parent monosaccharide, e.g., 6-O-Su-GalNAcα and GalNAcα1−3Galβ1−3(4)GlcNAcβ. The binding with several bacterial polysaccharides that have no structural resemblance to the affinity ligand GalNAcα was quite unexpected. Given that GalNAcα is considered the key fragment of the Tn antigen, it is surprising that these antibodies bind weakly GalNAcα−OSer and do not bind a wide variety of GalNAcα−OSer/Thr-containing mucin glycopeptides. At the same time, we have observed specific binding to cells having Tn-positive glycoproteins containing similar glycopeptide motifs in a conformationally rigid macromolecule. Thus, specific recognition of the Tn antigen apparently requires that the naturally occurring “anti-Tn” IgM recognize a complex epitope comprising the GalNAcα as an essential component and a fairly long amino acid sequence where the amino acids adjacent to GalNAcα do not contact the antibody paratope; i.e., the antibodies recognize a spatial epitope or a molecular pattern rather than a classical continuous sequence. In addition, we have not found any increase in the binding of natural antibodies when GalNAcα residues were clustered. These results may help in further development of anticancer vaccines based on synthetic Tn constructs.

Detection of three tumor biomarkers in human lung cancer serum using single particle inductively coupled plasma mass spectrometry combined with magnetic immunoassay

A new method for simultaneously determining cytokeratin fragment antigen 21–1 (CYFRA21-1), carcinoembryonic antigen (CEA), and carbohydrate antigen (CA15–3) was developed using single-particle, ICP-MS-based, magnetic immunoassay. Gold nanoparticles (AuNPs), ZnSe quantum dots (QDs), and Silver nanoparticles (AgNPs) were employed to tag antibodies. A highly efficient capture of CYFRA21-1, CEA, and CA15–3 was achieved using biotinylated, antibody-coated magnetic beads. AuNPs/ZnSe QDs/AgNPs-tagged second antibodies helped realize sensitive quantification of the target antigen using single particle ICP-MS. Under optimum conditions, CYFRA21-1, CEA, and CA15–3 linear concentration ranges were 0.05–50 ng mL−1, 0.02–100 ng mL−1, and 0.6–250 mU mL−1. The correlation coefficients were 0.9999, 0.9987, and 0.9970, respectively. CYFRA21-1, CEA, and CA15–3 detection limits were 0.02 ng mL−1, 0.006 ng mL−1, and 0.25 mU mL−1, respectively. Relative standard deviations (RSD) for CYFRA21-1, CEA, and CA15–3 were 3.2%, 4.4%, and 4.2%, respectively. The method simultaneously detected CYFRA21-1, CEA, and CA15–3 in human lung cancer serum samples with recoveries of between 89.8% and 101%.

Polysaccharide-enhanced ARGET ATRP signal amplification for ultrasensitive fluorescent detection of lung cancer CYFRA 21-1 DNA

An ultrasensitive fluorescence biosensor for detecting cytokeratin fragment antigen 21-1 (CYFRA 21-1) DNA of non-small cell lung carcinoma (NSCLC) is designed using polysaccharide and activator regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) signal amplification strategy. Thiolated peptide nucleic acid (PNA) is fixed on magnetic nanoparticles (MNPs) by a cross-linking agent and hybridized with CYFRA 21-1 DNA. Hyaluronic acid (HA) is linked to PNA/tDNA heteroduplexes in the form of carboxy-Zr4+-phosphate. Subsequently, multiple 2-bromo-2-methylpropionic acid (BMP) molecules are linked with HA to initiate ARGET ATRP reaction. Finally, a large number of fluorescein o-acrylate (FA) monomers are polymerized on the macro-initiators, and the fluorescence signal is significantly amplified. Under optimal conditions, this biosensor shows a significant linear correlation between the fluorescence intensity and logarithm of CYFRA 21-1 DNA concentration (0.1 fM to 0.1nM), and the limit of detection is as low as 78 aM. Furthermore, the sensor has a good ability to detect CYFRA 21-1 DNA in serum samples and to recognize mismatched bases. It suggests that the strategy has broad application in early diagnosis by virtue of its high sensitivity and selectivity. Graphical abstract A novel and highly sensitive fluorescence biosensor for quantitatively detecting CYFRA 21-1 DNA via dual signal amplification of hyaluronic acid and ARGET ATRP reaction was developed. This proposed method has a low detection limit, wide detection range, high selectivity, and strong anti-interference.