Cross-reactive Antibodies Research Articles

Longitudinal Analysis of Binding Antibody Levels Against 39 Human Adenovirus Types in Sera from 60 Regular Blood Donors from Greifswald, Germany, over 5 Years from 2018 to 2022

Adenoviruses are important human pathogens that are widespread and mainly associated with respiratory and gastrointestinal infections. In a previous study on human adenovirus (HAdV) seroprevalence, we observed reduced binding antibody levels against a range of HAdV types in sera collected from students in 2021 compared to sera collected before the SARS-CoV-2 pandemic. In this follow-up study, we wanted to verify this observation in a cohort of regular blood donors for whom serial samples were available. Therefore, HAdV-specific binding antibody levels were analyzed in sera collected over a 5-year period from 2018 to 2022 in a cohort of 60 regular donors to the blood bank of the University Hospital in Greifswald, Germany. Using ELISA-based assays, we quantified the binding antibody responses against 39 HAdV types. On the cohort level, we found largely stable antibody levels over the analyzed time period, with the highest antibody responses against HAdV-C1, -D25, -D26, -E4, -D10, -D27, -C5, -D75, -C2, and -C6. Only minor but significant reductions in comparison to the first serum samples from 2018 were detected for antibody levels in 2021 and 2022 against the low-prevalent types HAdV-A31, -D8, -D20, -D37, -D65, and -D69. On the other hand, we detected fluctuations in antibody levels on the individual level, with strong increases in antibody levels indicative of novel antigen contact. Interestingly, we frequently found simultaneous changes in antibody responses against multiple HAdV types, resulting in strong correlations of antibody responses against distinct clusters of HAdVs suggesting extensive cross-reactivity of HAdV-specific antibodies. To our knowledge, this is the first study of antibodies against a broad range of HAdV types in serum samples collected from a cohort of individuals over a prolonged period, and our data provide important insight into the long-term stability of HAdV-specific antibody levels. In this cohort of regular blood donors, we did not observe any major impact of the SARS-CoV-2 pandemic on HAdV immunity. Correlations of changes in antibody levels against different types indicate cross-reactivity of HAdV-specific antibodies that are important to consider for HAdV vector development. Our data also reveal possible candidates for future development of HAdV-based vectors.

Enhanced Broad-Spectrum Efficacy of an L2-Based mRNA Vaccine Targeting HPV Types 6, 11, 16, 18, with Cross-Protection Against Multiple Additional High-Risk Types

Background: Current L1-based human papillomavirus (HPV) vaccines provide type-specific protection but offer limited cross-protection against non-vaccine HPV types. Therefore, developing a broad-spectrum HPV vaccine is highly desirable. Methods: In this study, we optimized mRNA constructs and developed a multivalent L2-based mRNA vaccine encoding L2 aa 2-130, which includes all known neutralizing epitopes from four prevalent HPV types (HPV-6, -11, -16, and -18). We evaluated its immunogenicity in a mouse model and compared the efficacy of a commercially available mRNA delivery reagent with a custom-synthesized lipid nanoparticle (LNP) formulation. Results: We identified that a construct containing E01 (a 5′-untranslated region) and SL2.7 (a poly(A) polymerase recruitment sequence) significantly increased protein expression. The L2-based mRNA vaccine induced robust and long-lasting humoral immune responses, with significant titers of cross-reactive serum IgG antibodies against L2 epitopes. Notably, the vaccine elicited cross-neutralizing antibodies and conferred cross-protective immunity not only against vaccine-targeted HPV types but also against non-vaccine HPV types, following intravaginal challenge in mice. We also found that LNP delivered mRNA more effectively in vivo. Conclusions: The L2-based mRNA vaccine developed in this study shows significant potential for broad-spectrum protection against multiple HPV types. This approach offers a promising strategy for reducing the global burden of HPV-associated cancers.

Molecular mimicry as a mechanism of viral immune evasion and autoimmunity

Mimicry of host protein structures, or ‘molecular mimicry’, is a common mechanism employed by viruses to evade the host’s immune system. Short linear amino acid (AA) molecular mimics can elicit cross-reactive antibodies and T cells from the host, but the prevalence of such mimics throughout the human virome has not been fully explored. Here we evaluate 134 human-infecting viruses and find significant usage of linear mimicry across the virome, particularly those in the Herpesviridae and Poxviridae families. Furthermore, host proteins related to cellular replication and inflammation, autosomes, the X chromosome, and thymic cells are enriched as viral mimicry targets. Finally, we find that short linear mimicry from Epstein-Barr virus (EBV) is higher in auto-antibodies found in patients with multiple sclerosis than previously appreciated. Our results thus hint that human-infecting viruses leverage mimicry in the course of their infection, and that such mimicry may contribute to autoimmunity, thereby prompting potential targets for therapies.

CXCL13 promotes broad immune responses induced by circular RNA vaccines.

Antibody responses induced by current vaccines for influenza and SARS-CoV-2 often lack robust cross-reactivity. As hubs where diverse immune cells converge and interact, the alterations in the immune microenvironment within lymph nodes (LNs) are intricately linked to immune responses. Herein, we designed a lipid nanoparticle (LNP) loaded with circular RNA (circRNA) and targeted to LNs, in which CXCL13 was directly integrated into antigen-encoding circRNA strands. We demonstrated that CXCL13 alters the transcriptomic profiles of LNs, especially the upregulation of IL-21 and IL-4. Meanwhile, CXCL13 promotes the formation of germinal center and elicits robust antigen-specific T cell responses. With the codelivery of CXCL13 and the antigen, CXCL13 enhances cross-reactive antibodies against influenza virus and SARS-CoV-2, achieving protection against both homologous and heterologous influenza virus challenges in a mouse model. Notably, the targeted modification of LNP surfaces with antibodies helps address some of the challenges associated with lyophilized LNP vaccines, which is crucial for the long-term storage of LNP-circRNA vaccines. Overall, the circRNA-based antigen-CXCL13 coexpression system developed herein provides a simple and robust platform that enhances the magnitude and breadth of antibody responses against multiple viral glycoproteins, highlighting the potential utility of CXCL13 in inducing broad immune responses.

Unveiling the Group A Streptococcus Vaccine-Based L-Rhamnose from Backbone of Group A Carbohydrate: Current Insight Against Acute Rheumatic Fever to Reduce the Global Burden of Rheumatic Heart Disease

Group A Streptococcus (GAS) is a widely distributed bacterium that is Gram-positive and serves as the primary cause of acute rheumatic fever (ARF) episodes. Rheumatic heart disease (RHD) is a sequela resulting from repeated ARF attacks which are also caused by repeated GAS infections. ARF/RHD morbidity and mortality rates are incredibly high in low- and middle-income countries. This is closely related to poor levels of sanitation which causes the enhanced incidence of GAS infections. Management of carditis in RHD cases is quite challenging, particularly in developing countries, considering that medical treatment is only palliative, while definitive treatment often requires more invasive procedures with high costs. Preventive action through vaccination against GAS infection is one of the most effective steps as a solution in reducing RHD morbidity and mortality due to curative treatments are expensive. Various developments of M-protein-based GAS vaccines have been carried out over the last few decades and have recently begun to enter the clinical stage. Nevertheless, this vaccination generates cross-reactive antibodies that might trigger ARF assaults as a result of the resemblance between the M-protein structure and proteins found in many human tissues. Consequently, the development of a vaccine utilizing L-Rhamnose derived from the poly-rhamnose backbone of Group A Carbohydrate (GAC) commenced. The L-Rhamnose-based vaccine was chosen due to the absence of the Rhamnose biosynthesis pathway in mammalian cells including humans thus this molecule is not found in any body tissue. Recent pre-clinical studies reveal that L-Rhamnose-based vaccines provide a protective effect by increasing IgG antibody titers without causing cross-reactive antibodies in test animal tissue. These findings demonstrate that the L-Rhamnose-based vaccine possesses strong immunogenicity, which effectively protects against GAS infection while maintaining a significantly higher degree of safety.

Delineating the functional activity of antibodies with cross-reactivity to SARS-CoV-2, SARS-CoV-1 and related sarbecoviruses.

The recurring spillover of pathogenic coronaviruses and demonstrated capacity of sarbecoviruses, such SARS-CoV-2, to rapidly evolve in humans underscores the need to better understand immune responses to this virus family. For this purpose, we characterized the functional breadth and potency of antibodies targeting the receptor binding domain (RBD) of the spike glycoprotein that exhibited cross-reactivity against SARS-CoV-2 variants, SARS-CoV-1 and sarbecoviruses from diverse clades and animal origins with spillover potential. One neutralizing antibody, C68.61, showed remarkable neutralization breadth against both SARS-CoV-2 variants and viruses from different sarbecovirus clades. C68.61, which targets a conserved RBD class 5 epitope, did not select for escape variants of SARS-CoV-2 or SARS-CoV-1 in culture nor have predicted escape variants among circulating SARS-CoV-2 strains, suggesting this epitope is functionally constrained. We identified 11 additional SARS-CoV-2/SARS-CoV-1 cross-reactive antibodies that target the more sequence conserved class 4 and class 5 epitopes within RBD that show activity against a subset of diverse sarbecoviruses with one antibody binding every single sarbecovirus RBD tested. A subset of these antibodies exhibited Fc-mediated effector functions as potent as antibodies that impact infection outcome in animal models. Thus, our study identified antibodies targeting conserved regions across SARS-CoV-2 variants and sarbecoviruses that may serve as therapeutics for pandemic preparedness as well as blueprints for the design of immunogens capable of eliciting cross-neutralizing responses.

ABTrans: A Transformer-based Model for Predicting Interaction between Anti-Aβ Antibodies and Peptides.

Antibodies against Aβ peptide have been recently approved to treat Alzheimer's disease, underscoring the importance of understanding their interactions for developing more potent treatments. Here we investigated the interaction between anti-Aβ antibodies and various peptides using a deep learning model. Our model, ABTrans, was trained on dodecapeptide sequences from phage display experiments and known anti-Aβ antibody sequences sourced from public sources. It classified the binding ability between anti-Aβ antibodies and dodecapeptides into four levels: not binding, weak binding, medium binding, and strong binding, achieving an accuracy of 0.83. Using ABTrans, we examined the cross-reaction of anti-Aβ antibodies with other human amyloidogenic proteins, revealing that Aducanumab and Donanemab exhibited the least cross-reactivity. Additionally, we systematically screened interactions between eleven selected anti-Aβ antibodies and all human proteins to identify potential off-target candidates.

Characterization of cross-reactive, non-neutralizing monoclonal antibodies against a pandemic GII.4 norovirus variant.

To gain insights into the overall immune responses to human norovirus, we characterized non-neutralizing, cross-reactive monoclonal antibodies (mAbs) developed against a pandemic GII.4 norovirus. We determined the binding epitope of an antibody that exhibited cross-reactivity against all tested noroviruses, which makes it a useful tool for research and diagnostics. The epitope of two additional non-neutralizing mAbs was mapped to a less conserved region on the viral capsid protein, explaining their cross-reactivity patterns. Often overlooked, the role of non-neutralizing, cross-reactive mAbs merits further research to facilitate our understanding of immunity to norovirus infection and disease.

Recent Endemic Coronavirus Infection Associates With Higher SARS-CoV-2 Cross-Reactive Fc Receptor Binding Antibodies.

Recent documented infection with an endemic coronavirus (eCoV) associates with less severe coronavirus disease 2019 (COVID-19), yet the immune mechanism behind this protection has not been fully explored. We measured both antibody and T cell responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in SARS-CoV-2 naïve individuals classified into two groups, either with or without presumed recent eCoV infections. There was no difference in neutralizing antibodies and T cell responses against SARS-CoV-2 antigens between the two groups. SARS-CoV-2 naïve individuals with recent presumed eCoV infection, however, had higher levels of Fc receptor (FcR) binding antibodies against eCoV spikes (S) and SARS-CoV-2 S2. There was also a significant correlation between eCoV and SARS-CoV-2 FcR binding antibodies. Recent eCoV infection boosts cross-reactive antibodies that can mediate Fc effector functions, and this may play a role in the observed heterotypic immune protection against severe COVID-19.

Contribution of immunoglobulin products in influencing seasonal influenza infection and severity in antibody immune deficiency patients receiving immunoglobulin replacement therapy.

Seasonal and pandemic influenza infection present a potential threat to patients with antibody deficiency. The acceptance and effect of the current recommendation for annual vaccination against influenza for patients with antibody deficiency is not well investigated and due to antigenic drift or shift the protective capacity of regular IgG replacement therapy (IgRT) is considered low. This narrative review considers the effect of influenza vaccination in immunodeficient patients and discusses available information on the effect of immunoglobulin products on seasonal influenza infectivity and severity in antibody deficiency patients receiving IgRT. The humoral immune response to seasonal influenza vaccination is reduced in patients with antibody immune deficiency. However, there is no evidence that the proportion of patients with primary antibody deficiency who develop influenza illness, and the severity of such illness, is increased when compared with the general population. The IgRT that patients receive has been shown to contain neutralizing antibodies as a consequence of past flu infections against both the hemagglutinin and neuraminidase surface proteins and other viral internal proteins of different influenza A virus strains. Studies have demonstrated not only significant levels of specific but also cross-reactive antibodies against seasonal influenza virus strains. Thus, despite the yearly changes in influenza viral antigenicity that occur, IgRT could potentially contribute to the protection of patients against seasonal influenza. Currently, only limited clinical data are available confirming a preventative effect of IgRT with respect to seasonal influenza infection. In conclusion, there is some evidence that IgRT could contribute to protection against seasonal influenza in patients with antibody-related immunodeficiency. However, additional clinical data are needed to confirm the extent and relevance of this protection and identify the main responsible virus targets of that protection.

Zika virus T-cell based 704/DNA vaccine promotes protection from Zika virus infection in the absence of neutralizing antibodies.

Zika virus (ZIKV) and dengue virus (DENV) are closely related flaviviruses co-circulating in the same endemic areas. Infection can raise cross-reactive antibodies that can be either protective or increase risk of severe disease, depending on the infection sequence, DENV serotype and elapsed time between infection. On the contrast, T cell-mediated immunity against DENV and ZIKV is considered protective. Therefore, we have developed a T cell vaccine enriched in immunodominant T cell epitopes derived from ZIKV and evaluated its immunogenicity and efficacy against ZIKV and DENV infection. Mice were vaccinated using DNA vaccine platform using the tetrafunctional amphiphilic block copolymer 704. We show that vaccination of 2 different HLA class I transgenic mice with the ZIKV non-structural (NS) poly-epitope elicits T cell response against numerous ZIKV epitopes. Moreover, vaccination induces a significant protection against ZIKV infection, in the absence of neutralizing or enhancing antibodies against ZIKV. However, vaccination does not induce a significant protection against DENV2. In contrast, immunization with a DENV1-NS poly-epitope induces a significant protection against both DENV1 and DENV2, in the absence of humoral immunity. Taken together, we have shown that T-cell based vaccination could protect against multiple flavivirus infections and could overcome the complexity of antibody-mediated enhancement.

Navigating cross-reactivity and host species effects in a serological assay: A case study of the microscopic agglutination test for Leptospira serology.

Serology (the detection of antibodies formed by the host against an infecting pathogen) is frequently used to assess current infections and past exposure to specific pathogens. However, the presence of cross-reactivity among host antibodies in serological data makes it challenging to interpret the patterns and draw reliable conclusions about the infecting pathogen or strain. In our study, we use microscopic agglutination test (MAT) serological data from three host species [California sea lion (Zalophus californianus), island fox (Urocyon littoralis), and island spotted skunk (Spilogale gracilis)] with confirmed infections to assess differences in cross-reactivity by host species and diagnostic laboratory. All host species are known to be infected with the same serovar of Leptospira interrogans. We find that absolute and relative antibody titer magnitudes vary systematically across host species and diagnostic laboratories. Despite being infected by the same Leptospira serovar, three host species exhibit different cross-reactivity profiles to a 5-serovar diagnostic panel. We also observe that the cross-reactive antibody titer against a non-infecting serovar can remain detectable after the antibody titer against the infecting serovar declines below detectable levels. Cross-reactivity in serological data makes interpretation difficult and can lead to common pitfalls. Our results show that the highest antibody titer is not a reliable indicator of infecting serovar and highlight an intriguing role of host species in shaping reactivity patterns. On the other side, seronegativity against a given serovar does not rule out that serovar as the cause of infection. We show that titer magnitudes can be influenced by both host species and diagnostic laboratory, indicating that efforts to interpret absolute titers (e.g., as indicators of recent infection) must be calibrated to the system under study. Thus, we implore scientists and health officials using serological data for surveillance to interpret the data with caution.

B-060 Prevalence of CCD and profilins antibodies in a seasonal allergy study

Abstract Background Allergen sources are complex and heterogeneous mixtures of proteins, which may contain from innocuous IgE-binding structures such as CCDs (cross-reactive carbohydrate determinants), which are not associated with symptoms, to a panallergen such as profilin, which is associated with multiple sensitizations to pollen and pollen-food-latex syndromes. CCDs are present in many plant and animal allergens and cause strong cross-reactivity due to the high similarity of their structure. They complicate the interpretation of positive in vitro diagnostic results because they do not associate symptomatology and, thats why, the determination of specific IgE antibodies against CCDs can provide useful information when positive IgE results are not consistent with the clinical picture. Profilins are ubiquitous proteins present in all eukaryotic cells and identified as allergens in pollen, latex and plant foods. The highly conserved structure explains the cross-reactivity of IgE antibodies against plant profilins and their designation as panallergens. As a panallergen, profilin is associated with multiple pollen sensitization and pollen-food-latex syndromes that the allergist must be aware of for accurate diagnosis and successful treatment of allergic diseases. We intend to evaluate the prevalence of these two markers with a new diagnostic tool, since profilins and CCDs are the substances most likely to cause in vitro cross-reactivity. Methods In our study 8,242 adults who presented rhinoconjunctivitis and visited their primary care center were included. The samples were analyzed in serum samples which were routinely processed in our laboratory with the EUROLINE Mediterranean Inhalation 2 (IgE) assay from Euroimmun® from February to July 2023, according to the manufacturer’s protocols. Patients with specific IgE levels ≥ 0.35 kU/L were identified as sensitized to allergen. Results A total of 8,242 patients were enrolled in this study, 5,173 women and 3,069 men, ranging in age from 15 to 65 years. Of these, 279 patients (3.39%) had antibodies against CCD, 570 (6.92%) antibodies against profilins and 183 (2.22%) had both. A higher prevalence of these antibodies was observed in men (CCD, n = 168, 5.47%; Profilins, n = 308, 10.04%) than in women (CCD, n = 111, 2.15%; Profilins, n = 262, 5.06%). Both markers were more frequently found in the presence of specific IgE antibodies to grass and weed pollens. Conclusions The possibility of detecting the presence of IgE antibodies against CCD and panallergenic profilins is useful to detect cross-reactivity in vitro, which could explain the differences found between laboratory results and patients' symptoms, helping the allergist to make a diagnosis with greater certainty and accuracy.

Extraction and Analysis of Mycotoxins from Whole Wheat Flour - A Methods Efficiency Comparison

Abstract Wheat is considered as staple food source for 40% of the population worldwide. Yet, the yield and quality can be compromised by fungal diseases, which are also responsible for mycotoxins presence at wheat seeds and originating foodstuff. In this context, the tackling of this problem by developing regulatory limits and standards have induced the development of various methods for sampling, extraction, identification and quantification of mycotoxins in food samples. This review addresses the comparison of the technical and cost efficiency of methods for the extraction and qualitative- quantitative analysis of mycotoxins from whole wheat flour. Methods of extraction such as the Solvent Extraction method, the Liquid Liquid Extraction, the Solid Liquid Extraction, the Solid Phase Extraction, the Immuno-Affinity Columns, the QuEChERS, and the use of absorbent nanomaterials such as graphene oxide and multi-walled carbon nanotubes in extraction procedures, are described in principle, technical details are presented, and examples of reported use are given. Methods of mycotoxin analysis such as Immunological Assays (LFIA, ELISA, FPIA), the Sensor-based (Surface Plasmon Resonance Sensor, Piezoelectric Sensors, Electrochemical Sensors, Colorimetric Sensors), and Chromatographic Techniques (TLC, GC, HPLC, HPLC-FLD, LC-MS/MS, UPLC-MS/MS, UHPLC-MS/MS, UFLC-MS/MS) are reviewed. To compare their efficiency, main advantages and disadvantages, the ongoing improvements, as well as the validation parameters (linearity, recovery range, RSDr range, RSDR %, LOQ range, and cut off) are summarized, and pairing of extraction to analysis methods for specific mycotoxins is provided. It was evidenced that none of methods already in use is capable of analyzing all mycotoxin categories at once, because of their chemical characteristics (volatile/non-volatile, co-elution, UV absorption, fluorescence) versus methods restrictions (matrix interferences, cross-reactivity of antibodies, selectivity and reproducibility of data, need for derivatization, etc). Also, depending on the purpose of the analysis (research or screening as part of legal requirements), to date the immunological methods are only suitable for validated matrices, biosensors can be used for routine screening, and that GC-MS and HPLC-based methods fulfill the legal requirements. In conclusion, while the selectivity and accuracy of methods for mycotoxin detection is being improved rapidly (those sensor-based thanks to the use of nanoparticles, nanomaterials, aptasensors, etc., and the chromatographic techniques coupled with mass spectrometry offer a higher selectivity and sensitivity, low detection limits, maintained resolution performance), and the duration of the analysis, the cost, and the need for highly-skilled staff go in favor of rapid methods (immunological and sensors-based), it is the capacity to fulfill legal requirements, which will determine the trend and their future success in the market.

Synthesis of trisaccharide antigens featuring colitose, abequose and fucose residues and assessment of antibody binding on antigen arrays

Deoxy-hexose sugars, such as rhamnose and quinovose, and the dideoxy-hexoses colitose, abequose, and tyvelose are highly antigenic given that they are absent from animal glycoconjugates. To investigate the specificity of antibodies towards structurally similar carbohydrate epitopes found in bacteria, we synthesized trisaccharides containing colitose, abequose, and fucose motifs. Each trisaccharide was designed with a spacer ending with a primary amino group. These trisaccharide constructs were immobilized on O-succinimide coated glass slides alongside bacterial lipopolysaccharides (LPS) containing colitose, abequose, and fucose residues. We compared the recognition of the synthetic trisaccharides and natural LPS including structurally related epitopes by monoclonal and polyclonal antibodies targeting bacterial LPS. Additionally, we used arrays displaying the synthetic trisaccharides and natural LPS to assess the variability of IgA reactivity from breast milk samples towards the carbohydrate antigens. The results obtained underlined the cross-reactivity of polyclonal antibodies towards structurally related carbohydrate antigens and revealed a broad reactivity of breast milk-derived IgA towards the carbohydrate antigens tested. The significant cross-reactivity of antibodies towards structurally related LPS antigens may lead to false-positive detection of bacterial serotypes when used for diagnostic purposes.

Tonsil explants as a human in vitro model to study vaccine responses.

Vaccination is one of the most effective infection prevention strategies. Viruses with high mutation rates -such as influenza- escape vaccine-induced immunity and represent significant challenges to vaccine design. Influenza vaccine strain selection is based on circulating strains and immunogenicity testing in animal models with limited predictive outcomes for vaccine effectiveness in humans. We developed a human in vitro vaccination model using human tonsil tissue explants cultured in 3D perfusion bioreactors to be utilized as a platform to test and improve vaccines. Tonsils cultured in bioreactors showed higher viability, metabolic activity, and more robust immune responses than those in static cultures. The in vitro vaccination system responded to various premanufactured vaccines, protein antigens, and antigen combinations. In particular, a multivalent in vitro immunization with three phylogenetically distant H3N2 influenza strains showed evidence for broader B cell activation and induced higher antibody cross-reactivity than combinations with more related strains. Moreover, we demonstrate the capacity of our in vitro model to generate de novo humoral immune responses to a model antigen. Perfusion-cultured tonsil tissue may be a valuable human in vitro model for immunology research with potential application in vaccine candidate selection.

COVID-19 and Pulmonary Embolism: A Comprehensive Review of Epidemiology, Pathophysiology, and Management

Global public health has suffered greatly as a result of the coronavirus illness 2019 (Covid-19) pandemic; yet when vaccinations against Covid-19 are available, they have contributed to the containment of the spread of SARS Coronavirus 2 (SARS-CoV-2) infection. However, there have been isolated reports of vaccine-induced cerebral venous sinus thrombosis (CVST) and vaccine-induced immune thrombotic thrombocytopenia (VITT) following viral vector vaccinations (Ad26.COV2 vaccine, AdOx1 nCoV-19 vaccine).One of the most effective ways to address the global health issue as the new SARS-CoV-2 virus spreads around the world is immunization against COVID-19.This condition manifests as thrombocytopenia, the formation of an autoantibody against platelet-factor 4,and widespread thrombosis in unusual places, mainly in the cerebral venous. (PF4). The human Freia receptor on platelets can be bound by the PF4 autoantibody, which can then cause the platelets to aggregate. This is an uncommon side effect that closely mimics the clinical presentation of the traditional immune-mediated HIT illness that develops after heparin exposure. We will talk about the recently reported side effect known as vaccine-induced immune thrombotic thrombocytopenia (VITT),which can happen after receiving specific COVID-19 vaccinations, in this Spotlight. Since the vaccinations have been employed, questions have been raised about their safety. Following the COVID-19 vaccine, the most frequent side effects include local reactions at the injection site and general systemic symptoms like fever, headache, weariness, and myalgia. These side effects could appear shortly after immunization and go away quickly. Nonetheless, a few uncommon cases of vaccine-induced immune thrombotic thrombocytopenia (VITT) have been documented, mostly in relation to vaccinations utilizing viral vectors. Platelet expression of spike protein and subsequent immune response, platelet expression of other adenoviral proteins and subsequent reactions, the role of antibodies against platelet factor 4 (PF4), the direct interaction between adenoviral vector and platelets, the cross-reactivity of antibodies against SARS-CoV-2 spike protein with PF4, the cross-reactivity of anti-adenovirus antibodies and PF4 interaction between spike protein and platelets. Because severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can activate platelets, thrombocytopenia while rare in the first presentation may also be an indicator of the severity of the disease. The spike protein-angiotensin converting enzyme 2 (ACE2) connection causes this directly, and the activation of coagulation and inflammation causes it indirectly. In COVID-19, dysregulation of the innate and adaptive immune systems is a significant contributing factor to thrombosis and thrombocytopenia.

Longevity of hybrid immunity against SARS-CoV-2 in adults vaccinated with an adenovirus-based COVID-19 vaccine

BackgroundHybrid immunity provides better protection against COVID-19 than vaccination or prior natural infection alone. It induces high magnitude and broadly cross-reactive neutralising anti-Spike IgG antibodies. However, it is not clear how long these potent antibodies last, especially in the context of adenovirus-based COVID-19 vaccines.MethodsWe conducted a longitudinal cohort study and enrolled 20 adults who had received an adenovirus-based COVID-19 vaccine before a laboratory-confirmed SARS-CoV-2 infection. We followed up the study participants for 390 days post the initial breakthrough infection. We assessed the longevity and cross-reactive breadth of serum antibodies against SARS-CoV-2 variants of concern (VOCs), including Omicron.ResultsThe binding anti-Spike IgG antibodies remained within the reported putative levels for at least 360 days and were cross-neutralising against Beta, Gamma, Delta, and Omicron. During the follow up period, a median of one SARS-CoV-2 re-infection event was observed across the cohort, but none resulted in severe COVID-19. Moreover, the re-exposure events were associated with augmented anti-Spike and anti-RBD IgG antibody titres.ConclusionsThis study confirms that hybrid immunity provides durable broadly cross-reactive antibody immunity against SARS-CoV-2 variants of concern for at least a year (360 days), and that it is further augment by SARS-CoV-2 re-exposure.

Antibody Responses in SARS-CoV-2-Exposed and/or Vaccinated Individuals Target Conserved Epitopes from Multiple CoV-2 Antigens.

There is a need to investigate novel strategies in order to create an effective, broadly protective vaccine for current and future severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreaks. The currently available vaccines demonstrate compromised efficacy against emerging SARS-CoV-2 variants of concern (VOCs), short-lived immunity, and susceptibility to immune imprinting due to frequent boosting practices. In this study, we examined the specificity of cross-reactive IgG antibody responses in mRNA-vaccinated, AstraZeneca-vaccinated, and unvaccinated donors to identify potentially conserved, cross-reactive epitopes to target in order to create a broadly protective SARS-CoV-2 vaccine. Our study provides evidence for cross-reactive IgG antibodies specific to eight different spike (S) variants. Furthermore, the specificities of these cross-variant IgG antibody titers were associated to some extent with spike S1- and S2-subunit-derived epitopes P1 and P2, respectively. In addition, nucleocapsid (N)- and membrane (M)-specific IgG antibody titers correlated with N- and M-derived epitopes conserved across beta-CoVs, P3-7. This study reveals conserved epitopes of viral antigens, targeted by natural and/or vaccine-induced human immunity, for future designs of next-generation COVID-19 vaccines.

Rational selection of TbpB variants elucidates a bivalent vaccine formulation with broad spectrum coverage against Neisseria gonorrhoeae.

Neisseria gonorrhoeae is the causative agent of gonorrhea, an on-going public health problem due in part to the lack of success with efforts to develop an efficacious vaccine to prevent this sexually transmitted infection. An attractive candidate vaccine antigen because of its essential function and surface exposure, the gonococcal transferrin binding protein B (TbpB) exhibits high levels of antigenic variability which poses a significant obstacle in evoking a broadly protective vaccine composition. Here, we utilize phylogenetic information to rationally select TbpB variants for inclusion into a potential gonococcal vaccine and identify two TbpB variants that when formulated together elicit a highly cross-reactive antibody response in both rabbits and mice against a diverse panel of TbpB variants and clinically relevant gonococcal strains. Further, this formulation performed well in experimental proxies of real-world usage, including eliciting bactericidal activity against 8 diverse gonococcal strains and decreasing the median duration of colonization after vaginal infection in female mice by two heterologous strains of N. gonorrhoeae . Together, these data support the use of a combination of TbpB variants for a broadly protective gonococcal vaccine.