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SARS-CoV-2 epitope mapping on microarrays highlights strong immune-response to N protein region

Musicò, Angelo; Frigerio, Roberto; Mussida, Alessandro; Barzon, Luisa; Sinigaglia, Alessandro; Riccetti, Silvia; Gobbi, Federico; Piubelli, Chiara; Bergamaschi, Greta; Chiari, Marcella; Gori, Alessandro; Cretich, Marina

Abstract

A workflow for SARS-CoV-2 epitope discovery on peptide microarrays is herein reported. The process started with a proteome-wide screening of immunoreactivity based on the use of a high-density microarray followed by a refinement and validation phase on a restricted panel of probes using microarrays with tailored peptide immobilization through a click-based strategy. Progressively larger, independent cohorts of Covid-19 positive sera were tested in the refinement processes, leading to the identification of immunodominant regions on SARS-CoV-2 Spike (S), Nucleocapsid (N) protein and Orf1ab polyprotein. A summary study testing 50 serum samples highlighted an epitope of the N protein (region 155-171) providing 92% sensitivity and 100% specificity of IgG detection in Covid-19 samples thus being a promising candidate for rapid implementation in serological tests.

Generation of Chicken IgY against SARS-COV-2 Spike Protein and Epitope Mapping

Lu, Yan; Wang, Yajun; Zhang, Zhen; Huang, Jingliang; Yao, Meicun; Huang, Guobin; Ge, Yuanyuan; Zhang, Peichun; Huang, Huaxin; Wang, Yong; Li, Huiliang; Wang, Wen
Oct 2020
This new decade has started with a global pandemic of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), precipitating a worldwide health crisis and economic downturn. Scientists and clinicians have been racing against time to find therapies for COVID-19. Repurposing approved drugs, developing vaccines and employing passive immunization are three major therapeutic approaches to fighting COVID-19. Chicken immunoglobulin Y (IgY) has the potential to be used as neutralizing antibody against respiratory infections, and its advantages include high avidity, low risk of adverse immune responses, and easy local delivery by intranasal administration. In this study, we raised antibody against the spike (S) protein of SARS-CoV-2 in chickens and extracted IgY (called IgY-S) from egg yolk. IgY-S exhibited high immunoreactivity against SARS-CoV-2 S, and by epitope mapping, we found five linear epitopes of IgY-S in SARS-CoV-2 S, two of which are cross-reactive with SARS-CoV S. Notably, epitope SIIAYTMSL, one of the identified epitopes, partially overlaps the S1/S2 cleavage region in SARS-CoV-2 S and is located on the surface of S trimer in 3D structure, close to the S1/S2 cleavage site. Thus, antibody binding at this location could physically block the access of proteolytic enzymes to S1/S2 cleavage site and thereby impede S1/S2 proteolytic cleavage, which is crucial to subsequent virus-cell membrane fusion and viral cell entry. Therefore, the feasibility of using IgY-S or epitope SIIAYTMS-specific IgY as neutralizing antibody for preventing or treating SARS-CoV-2 infection is worth exploring.

Detection of specific IgE against linear epitopes from Gal d 1 has additional value in diagnosing hen’s egg allergy in adults

Ehlers, Anna M.; Otten, Henny G.; Wierzba, Eva; Flügge, Ulrike; Le, Thuy-My; Knulst, André C.; Suer, Waltraud
Background Although hen’s egg allergy is more prevalent in children, up to 0.6% of adults from different European countries suffers from a persistent or newly-onset hen’s egg allergy, making accurate diagnosis in adults necessary. However, sensitisation to hen’s egg extracts, components and linear epitopes are solely studied in children. Methods Hen’s egg allergic (n=16) and tolerant (n=20) adults were selected by sensitisation towards recombinant components rGal d 1 and/or 3. Sensitisation profiles towards egg white and yolk extract and the native components Gal d 1, 2, 3 and 4 were respectively evaluated with the ImmunoCAP or the EUROLINE system. Characterisation of linear epitopes was performed with a peptide microarray containing 15mer peptides representing the entire sequence of mature Gal d 1 and 3. Results Overall, sIgE titres against hen’s egg extracts and single components overlapped largely between allergic and tolerant adults. Although the median sIgE/sIgG4 ratio to Gal d 1 was increased in allergic adults, the range was comparable between both groups. Clinically relevant sensitisation to Gal d 1 was confirmed by sIgE-binding to the linear epitopes aa30-41, aa39-50 or aa84-95 in 6/13 allergic adults, mainly suffering from objective symptoms. In comparison, these epitopes were recognized by 1/15 tolerant patient. Only a few linear epitopes were detected for Gal d 3, suggesting a greater importance of conformational epitopes for the recognition of Gal d 3. Conclusion and Clinical Relevance Specific IgE-binding to linear epitopes of Gal d 1 is highly specific in identifying hen’s egg allergic adults with objective symptoms.

Rapid response to pandemic threats: immunogenic epitope detection of pandemic pathogens for diagnostics and vaccine development using peptide microarrays

Heiss, Kirsten; Heidepriem, Jasmin; Fischer, Nico; Weber, Laura K; Dahlke, Christine; Jaenisch, Thomas; Loeffler, Felix F
J. Proteome Res..
Sep 2020
Emergence and re-emergence of pathogens bearing the risk of becoming a pandemic threat are on the rise. Increased travel and trade, growing population density, changes in urbanization, and climate have a critical impact on infectious disease spread. Currently, the world is confronted with the emergence of a novel coronavirus SARS-CoV-2, responsible for yet more than 500 000 deaths globally. Outbreaks caused by viruses such as SARS-CoV-2, HIV, Ebola, influenza, and Zika have increased over the last decade, underlining the urgent need for a rapid development of diagnostics and vaccines. Hence, the rational identification of biomarkers for diagnostic measures on the one hand, and antigenic targets for vaccine development on the other, are of utmost importance. Peptide microarrays can display large numbers of putative target proteins translated into overlapping linear (and cyclic) peptides. Using these highly diverse libraries, covering tens of thousands of peptides, allow for the in-depth analysis of antibody signatures in a multiplexed, high-throughput fashion. In this review, we highlight synthesis platforms that facilitate fast and highly flexible generation of high-density peptide microarrays. We further outline the multifaceted applications of these peptide array platforms for the development of serological tests and vaccines, to quickly encounter pandemic threats.

Expression of different L1 isoforms of Mastomys natalensis papillomavirus as mechanism to circumvent adaptive immunity

Fu, Yingying; Cao, Rui; Schäfer, Miriam; Stephan, Sonja; Braspenning-Wesch, Ilona; Schmitt, Laura; Bischoff, Ralf; Müller, Martin; Schäfer, Kai; Vinzón, Sabrina E; Rösl, Frank; Hasche, Daniel
Although many high-risk mucosal and cutaneous human papillomaviruses (HPVs) theoretically have the potential to synthesize L1 isoforms differing in length, previous seroepidemiological studies only focused on the short L1 variants, co-assembling with L2 to infectious virions. Using the multimammate mouse Mastomys coucha as preclinical model, this is the first study demonstrating seroconversion against different L1 isoforms during the natural course of papillomavirus infection. Intriguingly, positivity with the cutaneous MnPV was accompanied by a strong seroresponse against a longer L1 isoform, but to our surprise, the raised antibodies were non-neutralizing. Only after a delay of around 4 months, protecting antibodies against the short L1 appeared, enabling the virus to successfully establish an infection. This argues for a novel humoral immune escape mechanism that may also have important implications on the interpretation of epidemiological data in terms of seropositivity and protection of PV infections in general.

Molecular and Serological Tests for COVID-19. A Comparative Review of SARS-CoV-2 Coronavirus Laboratory and Point-of-Care Diagnostics

Kubina, Robert; Dziedzic, Arkadiusz
Validated and accurate laboratory testing for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a crucial part of the timely management of Coronavirus Disease 2019 (COVID-19) disease, supporting the clinical decision-making process for infection control at the healthcare level and detecting asymptomatic cases. This would facilitate an appropriate treatment, a prompt isolation and consequently deceleration of the pandemic. Various laboratory tests can identify the genetic material of SARS-CoV-2 that causes COVID-19 in specimens, or specific anti-viral antibodies in blood/serum. Due to the current pandemic situation, a development of point-of-care diagnostics (POCD) allows us to substantially accelerate taking clinical decisions and implement strategic planning at the national level of preventative measures. This review summarizes and compares the available POCD and those currently under development, including quantitative reverse transcription PCR (RT-qPCR), serology immunoassays (SIAs) and protein microarray method (PMM) designed for standard and rapid COVID-19 diagnosis.

A cross-reactive mouse monoclonal antibody against rhinovirus mediates phagocytosis in vitro

Behzadi, Mohammad Amin; Choi, Angela; Duehr, James; Feyznezhad, Roya; Upadhyay, Chitra; Schotsaert, Michael; Palese, Peter; Nachbagauer, Raffael
Sci Rep.
Jun 2020
Rhinoviruses (RVs) are the main cause of the common cold worldwide. To date, more than 160 types of the virus have been recognized, categorized into three major species – A, B, and C. There are currently no approved vaccines available to prevent infection with RVs. To elicit antibodies against conserved regions located on capsid proteins of RV A viruses, mice were sequentially vaccinated with DNA plasmids encoding capsid proteins of different RV A types. After a final boost with whole virus, antibody-expressing hybridomas were generated. After isotyping, 11 monoclonal antibodies (mAbs) expressing an IgG subtype Fc-domain were selected for further expansion and purification. Three mAbs showed cross-reactivity against multiple strains of RV A viruses by ELISA, including strains A1A, A1B, A15, A16 and A49. Other mAbs had strain-specific binding patterns, with the majority of mAbs showing reactivity to RV-A15, the strain used for the final vaccination. We found that the RV-A15-specific mAbs, but not the cross-reactive mAbs, had neutralizing activity against RV-A15. An antibody dependent cellular phagocytosis (ADCP) assay revealed substantial ADCP activity for one of the cross-reactive mAbs. Epitope mapping of the neutralizing mAbs via escape mutant virus generation revealed a shared binding epitope on VP1 of RV-A15 for several neutralizing mAbs. The epitope of the ADCP-active, non-neutralizing mAb was determined by microarray analysis of peptides generated from the VP1 capsid protein. VP1-specific, cross-reactive antibodies, especially those with ADCP activity, could contribute to protection against RV infections.

Epitopes of Naturally Acquired and Vaccine‐induced Anti‐Ebola Virus Glycoprotein Antibodies in Single Amino Acid Resolution

Heidepriem, Jasmin; Krähling, Verena; Dahlke, Christine; Wolf, Timo; Klein, Florian; Addo, Marylyn M.; Becker, Stephan; Loeffler, Felix F.
Biotechnol. J..
May 2020
The Ebola virus (EBOV) can cause severe infections in humans, leading to a fatal outcome in a high percentage of cases. Neutralizing antibodies against the EBOV surface glycoprotein (GP) can prevent infections, demonstrating a straightforward way for an efficient vaccination strategy. Meanwhile, many different anti-EBOV antibodies have been identified, whereas the exact binding epitopes are often unknown. Here, the analysis of serum samples from an EBOV vaccine trial with the recombinant vesicular stomatitis virus-Zaire ebolavirus (rVSV-ZEBOV) and an Ebola virus disease survivor, using high-density peptide arrays, is presented. In this proof-of-principle study, distinct IgG and IgM antibodies binding to different epitopes of EBOV GP is detected: By mapping the whole GP as overlapping peptide fragments, new epitopes and confirmed epitopes from the literature are found. Furthermore, the highly selective binding epitope of a neutralizing monoclonal anti-EBOV GP antibody could be validated. This shows that peptide arrays can be a valuable tool to study the humoral immune response to vaccines in patients and to support Ebola vaccine development.

Lymphocyte predominant cells detect Moraxella catarrhalis-derived antigens in nodular lymphocyte-predominant Hodgkin lymphoma

Thurner, Lorenz; Hartmann, Sylvia; Fadle, Natalie; Regitz, Evi; Kemele, Maria; Kim, Yoo-Jin; Bohle, Rainer Maria; Nimmesgern, Anna; von Müller, Lutz; Kempf, Volkhard A. J.; Weniger, Marc A.; Neumann, Frank; Schneider, Nadine; Vornanen, Martine; Sundström, Christer; de Leval, Laurence; Engert, Andreas; Eichenauer, Dennis A.; Küppers, Ralf; Preuss, Klaus-Dieter; Hansmann, Martin-Leo; Pfreundschuh, Michael
Nat Commun.
May 2020
Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare lymphoma of B-cell origin with frequent expression of functional B-cell receptors (BCRs). Here we report that expression cloning followed by antigen screening identifies DNA-directed RNA polymerase beta’ (RpoC) from Moraxella catarrhalis as frequent antigen of BCRs of IgD+ LP cells. Patients show predominance of HLA-DRB1*04/07 and the IgVH genes encode extraordinarily long CDR3s. High-titer, light-chain-restricted anti-RpoC IgG1/κ-type serum-antibodies are additionally found in these patients. RpoC and MID/hag, a superantigen co-expressed by Moraxella catarrhalis that is known to activate IgD+ B cells by binding to the Fc domain of IgD, have additive activation effects on the BCR, the NF-κB pathway and the proliferation of IgD+ DEV cells expressing RpoC-specific BCRs. This suggests an additive antigenic and superantigenic stimulation of B cells with RpoC-specific IgD+ BCRs under conditions of a permissive MHC-II haplotype as a model of NLPHL lymphomagenesis, implying future treatment strategies.

Anti-PfGARP activates programmed cell death of parasites and reduces severe malaria

Raj, Dipak K.; Das Mohapatra, Alok; Jnawali, Anup; Zuromski, Jenna; Jha, Ambrish; Cham-Kpu, Gerald; Sherman, Brett; Rudlaff, Rachel M.; Nixon, Christina E.; Hilton, Nicholas; Oleinikov, Andrew V.; Chesnokov, Olga; Merritt, Jordan; Pond-Tor, Sunthorn; Burns, Lauren; Jolly, Grant; Ben Mamoun, Choukri; Kabyemela, Edward; Muehlenbachs, Atis; Lambert, Lynn; Orr-Gonzalez, Sachy; Gnädig, Nina F.; Fidock, David A.; Park, Sangshin; Dvorin, Jeffrey D.; Pardi, Norbert; Weissman, Drew; Mui, Barbara L.; Tam, Ying K.; Friedman, Jennifer F.; Fried, Michal; Duffy, Patrick E.; Kurtis, Jonathan D.
Nature.
Apr 2020
Malaria caused by Plasmodium falciparum remains the leading single-agent cause of mortality in children1, yet the promise of an effective vaccine has not been fulfilled. Here, using our previously described differential screening method to analyse the proteome of blood-stage P. falciparum parasites2, we identify P. falciparum glutamic-acid-rich protein (PfGARP) as a parasite antigen that is recognized by antibodies in the plasma of children who are relatively resistant—but not those who are susceptible—to malaria caused by P. falciparum. PfGARP is a parasite antigen of 80 kDa that is expressed on the exofacial surface of erythrocytes infected by early-to-late-trophozoite-stage parasites. We demonstrate that antibodies against PfGARP kill trophozoite-infected erythrocytes in culture by inducing programmed cell death in the parasites, and that vaccinating non-human primates with PfGARP partially protects against a challenge with P. falciparum. Furthermore, our longitudinal cohort studies showed that, compared to individuals who had naturally occurring anti-PfGARP antibodies, Tanzanian children without anti-PfGARP antibodies had a 2.5-fold-higher risk of severe malaria and Kenyan adolescents and adults without these antibodies had a twofold-higher parasite density. By killing trophozoite-infected erythrocytes, PfGARP could synergize with other vaccines that target parasite invasion of hepatocytes or the invasion of and egress from erythrocytes.

On‐Chip Neo‐Glycopeptide Synthesis for Multivalent Glycan Presentation

Mende, Marco; Tsouka, Alexandra; Heidepriem, Jasmin; Paris, Grigori; Mattes, Daniela S.; Eickelmann, Stephan; Bordoni, Vittorio; Wawrzinek, Robert; Fuchsberger, Felix F.; Seeberger, Peter H.; Rademacher, Christoph; Delbianco, Martina; Mallagaray, Alvaro; Loeffler, Felix F
Chem. Eur. J..
Apr 2020
Single glycan–protein interactions are often weak, such that glycan binding partners commonly utilize multiple, spatially defined binding sites to enhance binding avidity and specificity. Current array technologies usually neglect defined multivalent display. Laser-based array synthesis technology allows for flexible and rapid on-surface synthesis of different peptides. By combining this technique with click chemistry, neo-glycopeptides were produced directly on a functionalized glass slide in the microarray format. Density and spatial distribution of carbohydrates can be tuned, resulting in well-defined glycan structures for multivalent display. The two lectins concanavalin A and langerin were probed with different glycans on multivalent scaffolds, revealing strong spacing-, density-, and ligand-dependent binding. In addition, we could also measure the surface dissociation constant. This approach allows for a rapid generation, screening, and optimization of a multitude of multivalent scaffolds for glycan binding.

Mapping the epitopes of Schistosoma japonicum esophageal gland proteins for incorporation into vaccine constructs

Li, Xiao-Hong; Vance, Gillian M.; Cartwright, Jared; Cao, Jian-Ping; Wilson, R Alan; Castro-Borges, William
PLoS ONE.
Feb 2020
Background The development of a schistosome vaccine has proved challenging but we have suggested that characterisation of the self-cure mechanism in rhesus macaques might provide a route to an effective product. The schistosome esophagus is a complex structure where blood processing is initiated by secretions from anterior and posterior glands, achieved by a mixture of ~40 unique proteins. The mechanism of self-cure in macaques involves cessation of feeding, after which worms slowly starve to death. Antibody coats the esophagus lumen and disrupts the secretory processes from the glands, potentially making their secretions ideal vaccine targets. Methodology/Principal findings We have designed three peptide arrays comprising overlapping 15-mer peptides encompassing 32 esophageal gland proteins, and screened them for reactivity against 22-week infection serum from macaques versus permissive rabbit and mouse hosts. There was considerable intra- and inter-species variation in response and no obvious unique target was associated with self-cure status, which suggests that self-cure is achieved by antibodies reacting with multiple targets. Some immuno-dominant sequences/regions were evident across species, notably including: MEGs 4.1C, 4.2, and 11 (Array 1); MEG-12 and Aspartyl protease (Array 2); a Tetraspanin 1 loop and MEG-n2 (Array 3). Responses to MEGs 8.1C and 8.2C were largely confined to macaques. As proof of principle, three synthetic genes were designed, comprising several key targets from each array. One of these was expressed as a recombinant protein and used to vaccinate rabbits. Higher antibody titres were obtained to the majority of reactive regions than those elicited after prolonged infection. Conclusions/Significance It is feasible to test simultaneously the additive potential of multiple esophageal proteins to induce protection by combining their most reactive regions in artificial constructs that can be used to vaccinate suitable hosts. The efficacy of the approach to disrupt esophageal function now needs to be tested by a parasite challenge.

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