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Discover how PEPperPRINT Peptide Microarray products have been used in different fields of research.

Characterization of antibodies against the replication protein (Rep) encoded by bovine meat and milk factors (BMMFs)

Frehtman, Veronika; Shukla, Gunjan; Gentz, Michael; Müller, Marcus; Duduyemi, Oladimeji Paul; Grewe, Imke; Ernst, Claudia; Tessmer, Claudia; Didier, Andrea; Hofmann, Ilse; Bund, Timo; Leuchs, Barbara
Appl Microbiol Biotechnol.
Apr 2026
Abstract Bovine Meat and Milk Factors (BMMFs) are DNA elements with similarity to bacterial plasmids, are frequently identified in bovine meat and milk and were proposed to contribute to cancer development. All known BMMFs encode a conserved replication protein (Rep), allowing for histologic BMMF detection in clinical specimens based on Rep-directed mouse monoclonal antibodies (mAbs), which, however, have only been partially characterized so far. Here, 20 anti-BMMF Rep antibodies were assessed for biophysical properties, reactivity, specificity and binding sensitivity to five distinct BMMF Reps and other prokaryotic/eukaryotic target antigens using an enzyme-linked immunosorbent assay (ELISA)-based anti-BMMF Rep antibody binding assay. We demonstrated sensitive and specific antibody reaction with their respective Rep targets, according to the antibody immunization. Consensus antibodies raised against defined peptides of conserved Rep amino acid stretches interacted with most of the Rep antigens. Antibodies produced based on immunization with the Rep encoded on the BMMF isolate H1MSB.1, including rabbit and human chimeric variants, reacted only with the cognate H1MSB.1 Rep, with only two outliers targeting additional Reps. Completely new antibodies raised against the Rep of another isolate (C1HB.4) specifically detected the cognate C1HB.4 Rep antigen – not interacting with other Reps. New antibodies generated by triple Rep immunization (H1MSB.2/C1MI.3M.1/C1MI.9M.1 Rep) reacted to either all three or two immunization antigens without interacting with any other Reps. None of the antibodies cross-reacted against Reps of bacteria occurring during milk production or lysates of mammalian hosts. Competitive inhibition confirmed antigen-specificity across the antibody panel, which additionally did not show aberrancies concerning purity or antibody size for the majority of the tested Abs. These findings authenticate a highly specific panel of anti-BMMF Rep antibodies, which can serve as tools for BMMF detection in cancer and chronic diseases.**Key Points** • Anti-BMMF Rep antibodies are important to judge BMMFs’ role as cancer risk factors. • Selective binding of anti-BMMF Rep antibodies to BMMF Rep antigens. • No cross-reactivity of anti-BMMF Rep antibodies with bacterial and mammalian outgroup specimens.

Integrated reiterative pipeline for rapid epitope-based pan-alphavirus vaccines

Versiani, Alice F.; McCaffrey, Peter; Ribeiro-Filho, Helder V.; Silva, Natalia I. O.; Lopes-de-Oliveira, Paulo S.; Carrera, Jean-Paul; Nogueira, Mauricio L.; Marques, Rafael E.; Rossi, Shannan L.; Vasilakis, Nikos
Sci Adv.
Mar 2026
10.1126/sciadv.aeb2066
The vast diversity of the virosphere underscores the need for rapid, adaptable vaccine development infrastructures. Arthropod-borne zoonotic alphaviruses, in particular, continue to pose substantial threats to human and animal health. We present a fast, multitarget vaccine design pipeline integrating machine learning-based epitope prediction, protein modeling, and docking to prioritize viral peptides by immunogenicity, allele coverage, solubility, and stability. T cell epitopes were validated using peptide microarrays and molecular dynamics simulations, confirming receptor binding accuracy. Flow cytometry of murine and human peripheral blood mononuclear cells demonstrated robust T cell activation and cytokine secretion (IFN-γ, TNF-α, or IL-2), dependent on species and HLA allele. Final candidates were selected by composite immunogenicity scores. While this study primarily validates the T cell-specific arm of our predictive pipeline, complementary B cell epitope analyses are ongoing. Our findings support the development of broadly protective pan-alphaviral vaccines and the establishment of efficient, tunable processes for global vaccine development.

Identification of a conformational epitope on the E antigen implicated in anti-E alloimmunization

Matsuura, Hideaki; Yamada, Ayuna; Doi, Hiroki; Fujii, Sumie; Miura, Yasuo
Blood Adv.
Mar 2026
10.1182/bloodadvances.2025018046

Selective Targeting of Tip Endothelial Cells as a Therapeutic Strategy for Tumor Angiogenesis

Kim, Byoungmo; Lee, Ha Kyeong; Azam, Zulfikar; Choi, Jeong Uk; Wahab, Riajul; Lee, Na Kyeong; Ko, Yoon Gun; Choi, So‐Young; Lee, Se‐Ra; Shim, Wan Seob; Kim, Taeeung; Kim, In‐San; Alam, Farzana; Kim, Sang Yoon; Kim, Seong Who; Byun, Youngro; Al‐Hilal, Taslim A
Advanced Science.
Mar 2026
ABSTRACT Tip endothelial cells (TipEC), the leading edge of angiogenic sprouts, are essential for pathological neo‐vascularization but remain difficult to target due to the lack of specific druggable markers. Here, we identify Doppel as a selective and druggable regulator of endothelial tip cell function. Doppel expression enhances TipEC selection, directional migration, and regulates tip‐stalk cell dynamics by spatially controlling VEGFR2/Dll4/Src pathway. Genetic ablation of PRND (Doppel) reduces tip cell formation without affecting the stalk cells (StalkECs) number in tumors, indicating its selective role in TipECs. Importantly, depletion of TipECs using the first‐in‐class monoclonal antibodies against a highly conserved WQF‐motif of Doppel robustly decreased the growth of tumors by selectively downregulating VEGFR2+ TipECs but not StalkECs. These findings position Doppel as a tumor TipEC‐specific, druggable target that may offer a new avenue to enhance and refine anti‐angiogenic therapies in cancer treatment.

Clinical outcomes-dependent IgG epitope profiling in HTLV-1 reveals differential recognition of pathogen-derived antigens

Cilento, Natali Espasiani; Borges, João Vitor Da Silva; Machado, Nicolle Rakanidis; Do Nascimento, Lais Alves; Moreira, Anna Luisa Baratelli; Passos, Lhays Ozório; Santamarina, Aline Boveto; Casseb, Jorge; Sanabani, Sabri Saeed; Victor, Jefferson Russo
Front. Immunol..
Feb 2026
Human T-lymphotropic virus type 1 (HTLV-1) infection presents a wide clinical spectrum ranging from lifelong asymptomatic carriage to severe inflammatory neurodegeneration (HAM/TSP) or adult T-cell leukemia/lymphoma (ATLL). Although IgG responses contribute to viral control and immunopathology, the extent to which HTLV-1 clinical outcomes shape pathogen-derived IgG repertoires remains unclear. In this study, we applied a high-density infectious-disease epitope microarray containing 4,345 linear epitopes from viral, bacterial, parasitic, and fungal pathogens to profile IgG responses in healthy controls (HCs), asymptomatic carriers (ACs), HAM/TSP patients, and ATLL patients. Signal intensities were quantified in arbitrary units, and recognized epitopes were evaluated using similarity clustering (80% identity threshold) to assess repertoire structure. HTLV-1–infected individuals exhibited extensive remodeling of humoral immunity, with marked differences in the breadth and intensity of IgG recognition across clinical groups. HAM/TSP patients displayed broad and high-magnitude responses consistent with chronic inflammation and heightened Th1 activation, whereas ATLL patients recognized the largest number of epitopes but with distinct patterns indicative of altered B-cell regulation. Enhanced IgG responses to Mycobacterium tuberculosis, Strongyloides stercoralis, Toxoplasma gondii, and Plasmodium species were consistent with known co-infection susceptibilities in HTLV-1. Epitope similarity analysis revealed hundreds of low-redundancy clusters across all groups, arguing against simple linear cross-reactivity and suggesting phenotype-specific reshaping of B-cell selection and idiotypic networks. These findings demonstrate that HTLV-1 infection produces distinct, clinically dependent IgG epitope signatures across multiple pathogen classes, with potential relevance for understanding HTLV-1 pathogenesis and informing future studies integrating epitope mapping with B-cell repertoire analysis.

Non-Neutralizing Antibody Functions Predict Susceptibility to SARS-CoV-2 Infection after mRNA Booster Vaccination

Levy, Shlomia; Trifkovic, Sanja; Mielke, Dieter; Oppenheimer, Hannah; Goodman, Derrick; Ostrovsky, Daniel; Sanfield-Oakley, Sherry A.; Brackett, Caroline; Friedman, Lilach M; Kerkau, Melissa; Webby, Richard; Tomaras, Georgia; Guido, Ferrari; Nesher, Lior; Hertz, Tomer
Previous studies have shown that neutralizing and binding antibody titers are correlates of protection for symptomatic SARS-CoV-2 infection. We previously reported that individuals with low IgG and IgA baseline immune history (BIH) to SARS-CoV-2 variants were at increased risk of symptomatic infection in study of healthcare workers that received 3 or 4 doses of the Pfizer BNT-1262b2 vaccine. We also found that 1-month post-vaccination with the 4th booster dose, individuals with low-BIH mounted significant rises in binding and neutralizing antibody titers, to levels comparable to those of individuals with high-BIH, demonstrating that their increased risk was not due to inability to respond to vaccination. To further study the underlying factors that are associated with increased risk, we conducted a systems serology study of 40 low-BIH and 40 high-BIH individuals across 7 months of follow-up. We found that individuals with low BIH exhibited a significantly higher risk of symptomatic infection (HR=2.691, p=0.0065) and mounted weaker IgA and antibody-dependent cellular cytotoxicity (ADCC) responses compared to high-BIH individuals, particularly against Omicron and Delta variants. Baseline levels of the chemokine CXCL-11 were elevated in the low-BIH group. We then showed that baseline immune profiles can be used to train a prediction model of infection risk across 7 months of follow-up with 76% accuracy. IgA, ADCC and ADCP baseline features were dominant predictors of susceptibility. Our findings suggest that non-neutralizing antibody functions, especially IgA and ADCC, contribute to protection against symptomatic SARS-CoV-2 infection and that serology-guided stratification can enhance discovery of immune correlates of risk informing future vaccine design and deployment strategies.

Systematic analysis of the RGS2 degron reveals characteristics of substrate recognition by the F-box protein FBXO44

McNabb, Harrison J.; Cho, Eugene; Pitman, Mary; Rushton, Phillip S.; Mobley, David; Sjögren, Benita
Journal of Biological Chemistry.
Nov 2025
Regulator of G protein signaling 2 (RGS2) negatively modulates signaling downstream of G protein–coupled receptors by accelerating GTP hydrolysis at Gα subunits of heterotrimeric G proteins. Decreased RGS2 levels are implicated in numerous diseases, including cardiovascular disease and asthma. Thus, identifying selective means of enhancing RGS2 protein levels would be a viable therapeutic strategy. RGS2 is rapidly degraded through the ubiquitin–proteasomal pathway, and we previously identified F-box only protein 44 (FBXO44) as the substrate recognition component of the E3 ligase responsible for facilitating RGS2 degradation. As such, the RGS2–FBXO44 interaction is a potential target for pharmacological intervention. Detailed information on the FBXO44 recognition site (degron) in RGS2 will aid in structure-based small-molecule inhibitor design, as well as in identifying additional FBXO44 targets, which would help predict possible side effects of targeting this interaction. Thus, the goal of this study was to dissect the molecular properties for FBXO44 binding of the RGS2 degron. We used a peptide array utilizing systematic residue substitution, combined with AlphaFold modeling and molecular dynamics simulations, to identify several amino acid changes that altered binding both positively and negatively. Finally, we experimentally confirmed our results in cells through coimmunoprecipitation and proteasomal inhibition, using full-length RGS2. Altogether, these results provide structural insights into RGS2–FBXO44 binding, which will aid in structure-guided drug discovery efforts. It also provides a framework for building a consensus recognition motif for FBXO44, which could aid in identifying more substrates for this understudied F-box protein.

Severity-dependent IgG epitope profiling in COVID-19 reveals differential recognition of pathogen-derived antigens

Do Nascimento, Lais Alves; Machado, NicolleRakanidis; Borges, João Vitor Da Silva; Fagundes, Beatriz Oliveira; Bergamasco, Isabella Siuffi; Sgnotto, Fabio Da Ressureição; Bachi, André Luis Lacerda; Sato, Maria Notomi; Victor, Jefferson Russo
Front. Immunol..
Sep 2025
Background The contribution of antibody-mediated responses to COVID – 19 outcomes remains unclear, particularly regarding cross-reactivity with unrelated pathogens. While co-infections are known to influence disease progression, the broader landscape of IgG reactivity during SARS-CoV-2 infection has not been systematically explored. Methods We employed a high-density peptide microarray containing 4,344 linear epitopes from 37 viruses, 27 bacteria, 17 parasites, and 8 fungi to characterize serum IgG repertoires from individuals with moderate (n = 39) or severe (n = 40) COVID – 19. Controls included pre-pandemic healthy donors and a pooled intravenous immunoglobulin (IVIg) formulation. Data analysis included intensity ranking, epitope mapping, and comparative analysis of mean signal intensities for each epitope between the COVID-Mod and COVID-Sev groups. Results COVID – 19 patients showed widespread IgG reactivity against diverse pathogens, with patterns differing by disease severity. Severe cases displayed broader and more intense reactivity, notably against hepatitis C virus (HCV), SARS-CoV-1, influenza A, Mycobacterium tuberculosis, and Plasmodium falciparum. Moderate cases showed preferential recognition of epitopes from HTLV-I, Neisseria meningitidis, and Trypanosoma cruzi. These findings suggest that SARS-CoV-2 infection modulates pre-existing humoral memory, possibly through epitope spreading or immune reprogramming. Conclusions SARS-CoV-2 infection reshapes the IgG epitope repertoire in a severity-dependent manner, extending to antigens from unrelated pathogens. This phenomenon may reflect underlying immune dysregulation or idiotype-driven interactions. Comprehensive profiling of pathogen-related IgG responses may reveal potential biomarkers of disease severity. This phenomenon may inform future investigations aimed at improving personalized management strategies for co-infected or immunocompromised patients.

Preclinical characterization of an active immunotherapy targeting calcitonin gene-related peptide

Boyd, Justin D.; Wang, Shixia; Lin, Hsiao-Wen; Hsieh, Yueh-Ting; Sun, Yu Shuang; Thibodeaux, Brett A.; Lu, Hanxin; Sahni, Jaya; Wiggins, Jonathan; Longo, Matthew S.; Brooks, Jeanne K.; Vroom, Madeline M.; Chang, Yi-Pin; Liu, Zhi; Ding, Shuang; Dodart, Jean-Cosme
Commun Med.
Apr 2025
Abstract **Background** The success of passive immunotherapies targeting Calcitonin gene-related peptide (CGRP) for managing migraine has prompted our efforts towards developing an active immunotherapy that induces the production of endogenous antibodies against CGRP. Achieving efficacious antibody titers via immunization could provide a more convenient and cost-effective treatment alternative to anti-CGRP monoclonal antibody (mAb) therapies. However, immunization against endogenous CGRP faces multiple challenges such as breaking immune tolerance, inducing sufficient antibody titers, and avoiding immune response-associated toxicity. **Methods** Synthetic peptide immunogens formulated in adjuvants were delivered intramuscularly. Serum samples were collected post immunization and used to measure antibody titers as well as for the isolation of antibodies specific to CGRP. Antibodies were characterized for their binding affinities and specificities. The capsaicin-induced increase in dermal blood flow model was used in rats for the assessment of the pharmacodynamic effect of immunization. **Results** Here we demonstrate that a peptide-based active immunotherapy designed to induce antibodies against CGRP promotes robust antibody titers across preclinical species. Characterization of the immune response strongly suggests that this peptide immunogen primarily stimulates a humoral response and only induced CGRP-specific antibodies. Antibodies produced by immunization are primarily IgG1 and demonstrate binding and activity potencies similar to marketed monoclonal antibodies against CGRP. Finally, immunization demonstrates in vivo efficacy in a rat pharmacodynamic model. **Conclusion** Our results strongly suggest that a peptide-based active immunotherapy against CGRP could provide an affordable and convenient therapeutic for the prevention of migraine.

A tumor-binding antibody with cross-reactivity to viral antigens

Campa, Michael J.; Gottlin, Elizabeth B.; Wiehe, Kevin; Patz, Edward F.
Cancer Immunol Immunother.
Feb 2025
**Background** We previously identified in non-small cell lung cancer (NSCLC) patients an autoantibody to complement factor H (CFH) that is associated with non-metastatic disease and longer time to progression in patients with stage I disease. A recombinant human antibody, GT103, was cloned from single B cells isolated from patients with the autoantibody. GT103 inhibits tumor growth and establishes an antitumor microenvironment. The anti-CFH autoantibody and GT103 recognize the epitope PIDNGDIT within the SCR19 domain of CFH. Here, we asked if this autoantibody could have originally arisen as a humoral response to a similar epitope in a viral protein from a prior infection. **Methods** Homologous viral peptides with high sequence identity to the core PIDNGDIT epitope sequence were identified and synthesized. NSCLC patient plasma containing anti-CFH autoantibodies were assayed by ELISA against these peptides. GT103 was assayed on a 4345-peptide pathogen microarray. **Results** Epitopes similar to the GT103 epitope are present in several viruses, including human metapneumovirus-1 (HMPV-1) that contains a sequence within attachment glycoprotein G that differs by one amino acid. Anti-CFH autoantibodies in NSCLC patient plasma weakly bound to an HMPV-1 peptide containing the epitope. GT103 cross-reacted with multiple viral epitopes on a peptide microarray, with the top hits being peptides in the human endogenous retrovirus-K polymerase (HERV-K pol) protein and measles hemagglutinin glycoprotein. GT103 bound the viral HMPV-1, HERV-K pol, and measles epitope peptides but with lower affinity compared to the GT103 epitope peptide. **Conclusion** These findings suggest that memory B cells against a viral target could have affinity matured to produce an antibody that recognizes a similar epitope on tumor cells and exhibits antitumor properties.

Investigation of Immunoreactivity Profiles and Epitope Landscape in Divergent COVID-19 Trajectories and SARS-CoV-2 Variants

Bihani, Surbhi; Ray, Arka; Borishetty, Dhanush; Tuckley, Chaitanya; Salkar, Akanksha; Acharjee, Arup; Shrivastav, Prithviraj; Shrivastav, Om; Shastri, Jayanthi; Agrawal, Sachee; Duttagupta, Siddhartha; Srivastava, Sanjeeva
J. Proteome Res..
Jan 2025
This study aimed to elucidate the complexity of the humoral immune response in COVID-19 patients with varying disease trajectories using a SARS-CoV-2 whole proteome peptide microarray chip. The microarray, containing 5347 peptides spanning the entire SARS-CoV-2 proteome and key variants of concern, was used to analyze IgG responses in 10 severe-to-recovered, 9 nonsevere-to-severe cases, and 10 control case (5 pre-pandemic and 5 SARS-CoV-2-negative) plasma samples. We identified 1151 IgG-reactive peptides corresponding to 647 epitopes, with 207 peptides being cross-reactive across 124 epitopes. Nonstructural protein 3 (nsp3) exhibited the highest number of total and unique epitopes, followed by the spike protein. nsp12 had the most number of cross-reactive epitopes. Peptides from the spike protein and nsps 2, 3, 5, and 13 were notably associated with recovery. Additionally, specific mutations in SARS-CoV-2 variants were found to alter peptide immunoreactivity, with some mutations (e.g., G142D, L452R, and N501Y) enhancing and others (e.g., R190S and E484 K) reducing immune recognition. These findings have critical implications for the development of diagnostics, vaccines, and therapeutics. Understanding the distribution of epitopes and the impact of viral mutations on antigenicity provides insights into immune evasion mechanisms, informing strategies for controlling COVID-19 and future coronavirus outbreaks.

High-throughput identification of immunoreactive peptides and corresponding proteins from Anaplasma platys and Ehrlichia canis using peptide microarray chips

Llanes, Alejandro; Madesh, Swetha; Brangulis, Kalvis; Rajeev, Sreekumari
Front Cell Infect Microbiol.
Jan 2025
10.3389/fcimb.2025.1671309
INTRODUCTION: Anaplasma platys and Ehrlichia canis are rickettsial pathogens infecting dogs, with a worldwide distribution. Both species are obligate intracellular pathogens and colonize bone marrow-derived cells, with coinfections frequently reported in dogs. Although E. canis immunodominant proteins have been thoroughly characterized, very few high-throughput studies have been conducted to identify immunogenic proteins from Anaplasma spp. In this study, we used a methodology based on peptide microarray chips to identify immunoreactive peptides, either shared or species-specific, in the complete theoretical proteomes of both pathogens. METHODS: B-cell epitopes were predicted in the corresponding proteins from both species and ranked for synthesis on the peptide microarrays. These microarrays were screened with serum samples from antibody-positive dogs, as well as negative control sera from unexposed dogs. Additionally, we assessed the feasibility of integrating evidence gathered at the level of individual peptides to identify potentially immunogenic proteins contributing to the patterns of immunoreactivity observed on microarrays. RESULTS: Screening of peptide microarrays resulted in complex antibody reactivity patterns against thousands of peptides. After discarding peptides with cross-reactivity to negative control sera, we identified over 1,200 immunoreactive peptides, including ~80 peptides shared between the two species with almost identical sequences. Despite screening linear peptides, we were able to identify proteins previously reported as immunodominant in E. canis, some of which contain predominantly conformational epitopes. DISCUSSION: Our results suggest that a high-throughput strategy based on peptide microarrays is an effective approach for the rapid identification of immunoreactive peptides and the underlying immunogenic proteins. This study provides a foundation for developing novel diagnostic tools and vaccine candidates against A. platys and E. canis, including potential combined or multivalent formulations targeting both pathogens.

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