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ACS Chemical Biology Jun 2024The binding affinity of antibodies to specific antigens stems from a remarkably broad repertoire of hypervariable loops known as complementarity-determining regions...
The binding affinity of antibodies to specific antigens stems from a remarkably broad repertoire of hypervariable loops known as complementarity-determining regions (CDRs). While recognizing the pivotal role of the heavy-chain 3 CDRs (CDR-H3s) in maximizing antibody-antigen affinity and specificity, the key structural determinants responsible for their adaptability to diverse loop sequences, lengths, and noncanonical structures are hitherto unknown. To address this question, we achieved a de novo synthesis of bulged CDR-H3 mimics excised from their full antibody context. CD and NMR data revealed that these stable standalone β-hairpin scaffolds are well-folded and retain many of the native bulge CDR-H3 features in water. In particular, the tryptophan residue, highly conserved across CDR-H3 sequences, was found to extend the kinked base of these β-bulges through a combination of stabilizing intramolecular hydrogen bond and CH/π interaction. The structural ensemble consistent with our NMR observations exposed the dynamic nature of residues at the base of the loop, suggesting that β-bulges act as molecular hinges connecting the rigid stem to the more flexible loops of CDR-H3s. We anticipate that this deeper structural understanding of CDR-H3s will lay the foundation to inform the design of antibody drugs broadly and engineer novel CDR-H3 peptide scaffolds as therapeutics.
PubMed: 38916527
DOI: 10.1021/acschembio.4c00236 -
Frontiers in Medicine 2024Immunotherapy targeted to immune checkpoint inhibitors, such as the program cell death receptor (PD-1) and its ligand (PD-L1), has revolutionized cancer treatment.... (Review)
Review
Immunotherapy targeted to immune checkpoint inhibitors, such as the program cell death receptor (PD-1) and its ligand (PD-L1), has revolutionized cancer treatment. However, it is now well-known that PD-1/PD-L1 immunotherapy response is inconsistent among patients. The current challenge is to customize treatment regimens per patient, which could be possible if the PD-1/PD-L1 expression and dynamic landscape are known. With positron emission tomography (PET) imaging, it is possible to image these immune targets non-invasively and system-wide during therapy. A successful PET imaging tracer should meet specific criteria concerning target affinity, specificity, clearance rate and target-specific uptake, to name a few. The structural profile of such a tracer will define its properties and can be used to optimize tracers in development and design new ones. Currently, a range of PD-1/PD-L1-targeting PET tracers are available from different molecular categories that have shown impressive preclinical and clinical results, each with its own advantages and disadvantages. This review will provide an overview of current PET tracers targeting the PD-1/PD-L1 axis. Antibody, peptide, and antibody fragment tracers will be discussed with respect to their molecular characteristics and binding properties and ways to optimize them.
PubMed: 38915766
DOI: 10.3389/fmed.2024.1401515 -
Scandinavian Journal of Rheumatology Jun 2024Autoantibodies directed against the intracellular protein bicaudal D2 (BICD2) have been identified as a specific marker of systemic sclerosis (SSc). Since autoantibodies...
OBJECTIVE
Autoantibodies directed against the intracellular protein bicaudal D2 (BICD2) have been identified as a specific marker of systemic sclerosis (SSc). Since autoantibodies are of value in predicting disease onset and identifying meaningful clinical subsets, as well as having prognostic value, this study aimed to establish the prevalence of BICD2 autoantibodies (anti-BICD2) in a cohort of patients with connective tissue disease and healthy controls.
METHOD
In this cross-sectional study, 363 patients with connective tissue disease (121 SSc, 141 systemic lupus erythematosus, 101 myositis, and 100 blood donors) were tested for the presence of anti-BICD2. All SSc patients were tested for specific anti-nuclear antibodies (ANAs), and clinical and laboratory associations were evaluated in the SSc patients, stratified by anti-BICD2 status.
RESULTS
In the SSc cohort, 35 patients had autoantibodies directed against BICD2. The specificity of anti-BICD2 in SSc patients was 96.5%; however, the sensitivity was only 28.9%. Anti-BICD2 and centromere autoantibodies were present together in 91% of the anti-BICD2-positive SSc patients, and in none of the cases was anti-BICD2 the only antibody present. Anti-BICD2-positive patients had lower forced expiratory volume in 1 s (FEV) (p = 0.01) and lower carbon monoxide transfer coefficient (K) (p = 0.01) than anti-BICD2-negative SSc patients, but they had higher forced vital capacity (p = 0.03).
CONCLUSION
Autoantibodies against BICD2 were highly specific for SSc patients. Reduced FEV and K in anti-BICD2-positive patients may indicate that the presence of anti-BICD2 is associated with altered lung function in an unknown pathophysiological manner, which awaits further elucidation.
PubMed: 38913821
DOI: 10.1080/03009742.2024.2335718 -
Food Chemistry: X Jun 2024Engineered bacterial magnetic nanoparticles (BMPs) fused with protein A (BMP-PA) can bind antibodies, creating immunomagnetic beads that offer an attractive tool for...
Engineered bacterial magnetic nanoparticles (BMPs) fused with protein A (BMP-PA) can bind antibodies, creating immunomagnetic beads that offer an attractive tool for targets screening. In the study, BMP-PA-IgG was formed by attaching broad-spectrum monoclonal antibodies against glucocorticoids (GCs) to BMP-PA. Immunomagnetic assay was developed for analysis of GCs, using the BMP-PA-IgG and hydrocortisone-horseradish peroxidase. The developed assay exhibited broad specificity for GCs, including hydrocortisone (HCS), betamethasone (BMS), dexamethasone (DMS), prednisolone (PNS), beclomethasone (BCMS), cortisone (CS), 6-α-methylprednisone (6-α-MPNS), and fludrocortisone acetate (HFCS), with half inhibitory concentrations (IC) ranging from 0.88 to 6.57 ng/mL. The proposed assay showed average recoveries of HCS and DMS ranging from 75.6% to 105.2% in chicken and pork samples, which were correlated well with those obtained by LC-MS/MS. This study indicated that the integration of engineered immunomagnetic beads into immunoassay systems offer possibilities for the sensitive and selective detection of GCs.
PubMed: 38911916
DOI: 10.1016/j.fochx.2024.101523 -
Clinical Medicine Insights. Oncology 2024Antibody-drug conjugates (ADCs), combining the cytotoxicity of the drug payload with the specificity of monoclonal antibodies, are one of the rapidly evolving classes of... (Review)
Review
Antibody-drug conjugates (ADCs), combining the cytotoxicity of the drug payload with the specificity of monoclonal antibodies, are one of the rapidly evolving classes of anti-cancer agents. These agents have been successfully incorporated into the treatment paradigm of many malignancies, including non-small cell lung cancer (NSCLC). The NSCLC is the most prevalent subtype of lung cancer, having a considerable burden on the cancer-related mortality and morbidity rates globally. Several ADC molecules are currently approved by the Food and Drug Administration (FDA) to be used in patients with NSCLC. However, the successful management of NSCLC patients using these agents was met with several challenges, including the development of resistance and toxicities. These shortcomings resulted in the exploration of novel therapeutic targets that can be targeted by the ADCs. This review aims to explore the recently identified ADC targets along with their oncologic mechanisms. The ADC molecules targeting these biomarkers are further discussed along with the evidence from clinical trials.
PubMed: 38911453
DOI: 10.1177/11795549241260534 -
Journal of Clinical Virology Plus Nov 2023While the global COVID-19 pandemic is slowly coming under control, current efforts are focused on understanding the epidemiology of endemic SARS-CoV-2. The tool of...
INTRODUCTION
While the global COVID-19 pandemic is slowly coming under control, current efforts are focused on understanding the epidemiology of endemic SARS-CoV-2. The tool of choice for doing so remains serological tests that detect SARS-CoV-2 induced antibodies. However, the performance of these tests should be evaluated to ensure they comply with the specific performance criteria desired by each country that they are used in.
METHODS
Here, we use pre-COVID-19 plasma and plasma from SARS-CoV-2-infected individuals collected in 2020, 2021 and 2022 to evaluate the performance of two commercial Rapid Lateral Flow (RLF) tests (the PANBIO™ COVID-19 IgG/IgM rapid test and the LABNOVATION™ COVID-19 (SARS-CoV-2) IgG/IgM rapid test) and one commercial ELISA test (the PLATELIA™ SARS-CoV-2 total Ab).
RESULTS
We find that whereas the specificity of the two RLF tests is ≥ 95%, it was 91% for the ELISA tests. However, at 14 days post-COVID-19 date of diagnosis (DoD), only the ELISA test constantly achieved a sensitivity of ≥80% over all the three years. In addition, the rate of detection of the two RLF tests varied across the years with a sensitivity ranging from <80% in 2021 to >80% in 2022. More importantly the capacity of these two RLF tests to detect IgG antibodies decreased with time. On the contrary, the sensitivity of the ELISA test was still above 80% more than six months post DoD.
CONCLUSION
We recommend that sero-epidemiological surveys focused on testing antibodies should not rely on performances reported by the assay manufacturers. They should include a formal evaluation of the selected assays to ensure its limitations and strengths conform with the data-accuracy requirements of the surveys.
PubMed: 38911322
DOI: 10.1016/j.jcvp.2023.100168 -
Archives of Biochemistry and Biophysics Jun 2024Affinity maturation increases antigen-binding affinity and specificity of antibodies by somatic hypermutation. Various monoclonal antibodies against...
Affinity maturation increases antigen-binding affinity and specificity of antibodies by somatic hypermutation. Various monoclonal antibodies against (4-hydroxy-3-nitrophenyl)acetyl (NP) were obtained during affinity maturation. Among them, highly matured anti-NP antibodies, such as E11 and E3, possess Cys96 and Cys100 in the complementarity-determining region 3 of the heavy chain, which would form a disulfide bond. In this study, we evaluated the effects of disulfide bonds on antigen binding by generating single-chain Fv (scFv) antibodies of E11 and its mutants, E11_C96K/C100E and E11_C96K/C100Q, and determined their antigen-binding thermodynamics and kinetics. The binding affinities of the Cys mutants were lower than that of E11 scFv, indicating that the disulfide bond contributed to antigen binding, especially for stable complex formation. This was also supported by the decreased affinity of E11 scFv in the presence of a reducing agent. The crystal structures of NP-free and NP-bound E11 scFvs were determined at high resolution, showing the existence of a disulfide bond between Cys96 and Cys100, and the antigen recognition mechanism, which could be compared with those of other anti-NP antibodies, such as germline-type N1G9 and matured-type C6, as reported previously. These structures could explain the molecular basis of changes in antigen-binding affinity and thermal stability in the absence or presence of antigens. Small-angle X-ray scattering further showed a local conformational change in E11 scFv upon antigen binding in solution.
PubMed: 38909835
DOI: 10.1016/j.abb.2024.110068 -
Medical Microbiology and Immunology Jun 2024Rapid tests allow outpatient, low cost, reliable, screening for chronic HIV infection. However, data regarding their sensitivity on primary infection remain scarce. The...
Rapid tests allow outpatient, low cost, reliable, screening for chronic HIV infection. However, data regarding their sensitivity on primary infection remain scarce. The objective of this study was to assess sensitivity of nine HIV rapid tests for primary HIV-1 infection screening. Seventy-five serum samples from patients during HIV-1 primary infection were included. Primary infection was diagnosed by a positive 4th generation ELISA and HIV-1 RNA positivity confirmed by Western blot patterns associated with HIV-1 primary infection. Early seroconversion was defined as the absence of antibodies on HIV-1 Western blot associated with HIV-1 RNA and p24-antigen positivity. An identical sensitivity (95% CI) of 76.7% (65.2-84.2%) was observed for HIV 1/2 STAT-PAK Assay (STAT-PAK), INSTI™ HIV-1/HIV-2 antibody Test (INSTI), SURE CHECK HIV 1/2 (SURE CHECK) and MULTISURE HIV rapid test (MULTISURE) with visual reading. Sensitivity was 74.7% (63.8-83.1%) for MULTISURE (automatic reading), 77.0% (66.3-85.1%) for FIRST RESPONSE Test VIH 1-2.O CARTE (FIRST RESPONSE), 83.8% (73.8-90.5%) for VIKIA HIV1/2 (VIKIA), 88.0% (78.7-93.6%) for Genie™ Fast HIV 1/2 (Genie Fast), 88.6% (79.0-94.1%) for Hexagon HIV (Hexagon), and 92.8% (83.6-96.3%) for Exacto TEST HIV Pro (Exacto). However, rapid tests performed poorly for the early seroconversion subgroup (n = 14), with sensitivities ranging from 7% (1.3-31.5%) for STAT-PAK, INSTI, SURE CHECK, MULTISURE (automatic reading), to 29% (12-55%) for FIRST RESPONSE, 31% (13-58%) for VIKIA, 43% (21-67%) for Hexagon and 57.1% (32.6-78.6%) for Exacto and Genie Fast. Overall, despite significant discrepancies in sensitivity, HIV rapid tests should be used with caution in the context of a suspected primary infection.
Topics: Humans; HIV Infections; Sensitivity and Specificity; HIV-1; Male; Mass Screening; Female; Adult; HIV Antibodies; Middle Aged; RNA, Viral; Enzyme-Linked Immunosorbent Assay; Young Adult; Blotting, Western; Diagnostic Tests, Routine; HIV Testing
PubMed: 38907945
DOI: 10.1007/s00430-024-00792-1 -
Journal of Hazardous Materials Jun 2024Time-resolved fluorescent lateral immunoassay strip (TRFLIS) is a reliable and rapid method for detecting acetamiprid. However, its sensitivity is often affected by the...
Time-resolved fluorescent lateral immunoassay strip (TRFLIS) is a reliable and rapid method for detecting acetamiprid. However, its sensitivity is often affected by the structural patterns and stability of the fluorescent probe. Researchers have shown significant interests in using goat anti-mouse IgG (GaMIgG) which is indirectly bound to time-resolved fluorescent microsphere (TRFM) and antibody. This allowed for oriented modification of the antibody. However, the stability of fluorescent probe in this binding mode remained unexplored. Herein, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride was innovatively used as a cross-linking agent to enhance the binding of antibody to GaMIgG, which improved the stability of the fluorescent probe. Under optimal working conditions, this strategy exhibited a wide linear response range of 5-700 ng/mL. Its limit of detection (LOD) was 0.62 ng/mL, the visual LOD was 5 ng/mL, and the limit of quantification (LOQ) of 2.06 ng/mL. Additionally, under tomato matrix, leek matrix and Chinese cabbage matrix, the linear response ranges were 5-400, 5-300, and 5-700 ng/mL, with LODs of 0.16, 0.60, and 0.41 ng/mL, with LOQs of 0.53, 2.01 and 1.37 ng/mL, respectively. In conclusion, this strategy effectively reduced the dosage of acetamiprid antibody compared with TRFM directly linking acetamiprid antibody, and greatly increased the sensitivity of TRFLIS. Meanwhile, it demonstrated outstanding specificity and accuracy in acetamiprid detection and had been successfully applied to vegetable samples. This method enables rapid and accurate detection of large-volume samples by combining qualitative and quantitative methods. As such, it has great potential in the development of low-cost and high-performance immunochromatographic platforms.
PubMed: 38905980
DOI: 10.1016/j.jhazmat.2024.134935 -
Polish Journal of Microbiology Jun 2024Serological testing can be a powerful complementary approach to achieve timely diagnosis of severe acute respiratory coronavirus 2 (SARS-CoV-2) infection, along with... (Review)
Review Comparative Study
Serological testing can be a powerful complementary approach to achieve timely diagnosis of severe acute respiratory coronavirus 2 (SARS-CoV-2) infection, along with nucleic acid detection. Immunoglobulin (Ig) A antibodies are less frequently utilized to detect SARS-CoV-2 infection than IgM and IgG antibodies, even though IgA antibodies play an important role in protective immunity against SARS-CoV-2. This review discusses the differences in kinetics and assay performance between IgA and IgM antibodies and the factors influencing antibody responses. It highlights the potential usefulness of analyzing IgA antibodies for the early detection of SARS-CoV-2 infection. The early appearance of IgA and the high sensitivity of IgA-based immunoassays can aid in diagnosing coronavirus disease 2019. However, because of cross-reactivity, it is important to recognize the only moderate specificity of the early detection of SARS-CoV-2 IgA antibodies against spike antigens. Either the analysis of antibodies targeting the nucleocapsid antigen or a combination of antibodies against the nucleocapsid and spike antigens may strengthen the accuracy of serological evaluation.
Topics: Humans; COVID-19; Immunoglobulin A; Immunoglobulin M; SARS-CoV-2; Antibodies, Viral; Early Diagnosis; COVID-19 Serological Testing; Sensitivity and Specificity
PubMed: 38905276
DOI: 10.33073/pjm-2024-019