Antibody isotype epitope mapping of SARS-CoV-2 Spike RBD protein: Targets for COVID-19 symptomatology and disease control.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) still poses a challenge for biomedicine and public health. To advance the development of effective diagnostic, prognostic, and preventive interventions, our study focused on high-throughput antibody binding epitope mapping of the SARS-CoV-2 spike RBD protein by IgA, IgM and IgG antibodies in saliva and sera of different cohorts from healthy uninfected individuals to SARS-CoV-2-infected unvaccinated and vaccinated asymptomatic, recovered, nonsevere, and severe patients. Identified candidate diagnostic (455-LFRKSNLKPFERD-467), prognostic (395-VYADSFVIRGDEV-407-C-KLH, 332-ITNLCPFGEV-342-C-KLH, 352-AWNRKRI-358-C-KLH, 524-VCGPKKSTNLVKN-536-KLH), and protective (MKLLE-487-NCYFPLQSYGFQPTNGVG-504-GGGGS-446-GGNYNYLYRLFRKSNLKPFERD-467) epitopes were validated with sera from prevaccine and postvaccine cohorts. The results identified neutralizing epitopes and support that antibody recognition of linear B-cell epitopes in RBD protein is associated with antibody isotype and disease symptomatology. The findings in asymptomatic individuals suggest a role for anti-RBD antibodies in the protective response against SARS-CoV-2. The possibility of translating results into diagnostic interventions for the early diagnosis of asymptomatic individuals and prognosis of disease severity provides new tools for COVID-19 surveillance and evaluation of risks in hospitalized patients. These results, together with other approaches, may contribute to the development of new vaccines for the control of COVID-19 and other coronavirus-related diseases using a quantum vaccinomics approach through the combination of protective epitopes.

Serum biomarkers for nutritional status as predictors in COVID-19 patients before and after vaccination.

The aim of this study was to characterize serum protein biomarkers for nutritional status that may be used as predictors for disease symptomatology in COVID-19 patients before and after vaccination. In pre-vaccine cohorts, proteomics analysis revealed significant differences between groups, with serum proteins alpha-1-acid glycoproteins (AGPs) 1 and 2, C-reactive protein (CRP) and retinol binding protein (RBP) increasing with COVID-19 severity, in contrast with serum albumin, transthyretin (TTR) and serotransferrin (TF) reduction as the symptomatology increased. Immunoassay reproduced and validated proteomics results of serum proteins albumin and RBP. In post-vaccine cohorts, the results showed the same pattern as in pre-vaccine cohorts for serum proteins AGPs, CRP, albumin and TTR. However, TF levels were similar between groups and RBP presented a slight reduction as COVID-19 symptomatology increased. In these cohorts, immunoassay validated proteomics results of serum proteins albumin, TTR and TF. Additionally, immune response to α-Gal in pre-vaccine cohorts varied in predominant immunoglobulin type profile, while post-vaccine groups presented mainly anti-α-Gal protective IgG antibodies. The study identified serum nutritional biomarkers that could potentially predict an accurate prognostic of COVID-19 disease to provide an appropriate nutritional care and guidance in non-vaccinated and vaccinated individuals against SARS-CoV-2. These results highlight the importance of designing personalized nutrition protocols to improve diet along with the application of prebiotics or probiotics for the control of COVID-19 and other infectious diseases.

Correlates with Vaccine Protective Capacity and COVID-19 Disease Symptoms Identified by Serum Proteomics in Vaccinated Individuals.

In the last two years, the coronavirus disease 19 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been a scientific and social challenge worldwide. Vaccines have been the most effective intervention for reducing virus transmission and disease severity. However, genetic virus variants are still circulating among vaccinated individuals with different disease symptomatology. Understanding the protective- or disease-associated mechanisms in vaccinated individuals is relevant to advances in vaccine development and implementation. To address this objective, serum-protein profiles were characterized by quantitative proteomics and data-analysis algorithms in four cohorts of uninfected and SARS-CoV-2-infected vaccinated individuals with asymptomatic, non-severe, and severe disease symptomatology. The results show that immunoglobulins were the most overrepresented proteins in infected cohorts when compared to PCR-negative individuals. The immunoglobulin profile varied between different infected cohorts and correlated with protective- or disease-associated capacity. Overrepresented immunoglobulins in PCR-positive individuals correlated with protective response against SARS-CoV-2, other viruses, and thrombosis in asymptomatic cases. In non-severe cases, correlates of protection against SARS-CoV-2 and HBV together with risk of myasthenia gravis and allergy and autoantibodies were observed. Patients with severe symptoms presented risk for allergy, chronic idiopathic thrombocytopenic purpura, and autoantibodies. The analysis of underrepresented immunoglobulins in PCR-positive compared to PCR-negative individuals identified vaccine-induced protective epitopes in various coronavirus proteins, including the spike receptor-binding domain RBD. Non-immunoglobulin proteins were associated with COVID-19 symptoms and biological processes. These results evidence host-associated differences in response to vaccination and the possibility of improving vaccine efficacy against SARS-CoV-2.

Characterization by Quantitative Serum Proteomics of Immune-Related Prognostic Biomarkers for COVID-19 Symptomatology.

The COVID-19 pandemic caused by SARS-CoV-2 challenges the understanding of factors affecting disease progression and severity. The identification of prognostic biomarkers and physiological processes associated with disease symptoms is relevant for the development of new diagnostic and therapeutic interventions to contribute to the control of this pandemic. To address this challenge, in this study, we used a quantitative proteomics together with multiple data analysis algorithms to characterize serum protein profiles in five cohorts from healthy to SARS-CoV-2-infected recovered (hospital discharge), nonsevere (hospitalized), and severe [at the intensive care unit (ICU)] cases with increasing systemic inflammation in comparison with healthy individuals sampled prior to the COVID-19 pandemic. The results showed significantly dysregulated proteins and associated biological processes and disorders associated to COVID-19. These results corroborated previous findings in COVID-19 studies and highlighted how the representation of dysregulated serum proteins and associated BPs increases with COVID-19 disease symptomatology from asymptomatic to severe cases. The analysis was then focused on novel disease processes and biomarkers that were correlated with disease symptomatology. To contribute to translational medicine, results corroborated the predictive value of selected immune-related biomarkers for disease recovery [Selenoprotein P (SELENOP) and Serum paraoxonase/arylesterase 1 (PON1)], severity [Carboxypeptidase B2 (CBP2)], and symptomatology [Pregnancy zone protein (PZP)] using protein-specific ELISA tests. Our results contributed to the characterization of SARS-CoV-2-host molecular interactions with potential contributions to the monitoring and control of this pandemic by using immune-related biomarkers associated with disease symptomatology.

The antibody response to the glycan α-Gal correlates with COVID-19 disease symptoms.

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected millions of people worldwide. Characterization of the immunological mechanisms involved in disease symptomatology and protective response is important to progress in disease control and prevention. Humans evolved by losing the capacity to synthesize the glycan Galα1-3Galß1-(3)4GlcNAc-R (α-Gal), which resulted in the development of a protective response against pathogenic viruses and other microorganisms containing this modification on membrane proteins mediated by anti-α-Gal immunoglobulin M (IgM)/IgG antibodies produced in response to bacterial microbiota. In addition to anti-α-Gal antibody-mediated pathogen opsonization, this glycan induces various immune mechanisms that have shown protection in animal models against infectious diseases without inflammatory responses. In this study, we hypothesized that the immune response to α-Gal may contribute to the control of COVID-19. To address this hypothesis, we characterized the antibody response to α-Gal in patients at different stages of COVID-19 and in comparison with healthy control individuals. The results showed that while the inflammatory response and the anti-SARS-CoV-2 (Spike) IgG antibody titers increased, reduction in anti-α-Gal IgE, IgM, and IgG antibody titers and alteration of anti-α-Gal antibody isotype composition correlated with COVID-19 severity. The results suggested that the inhibition of the α-Gal-induced immune response may translate into more aggressive viremia and severe disease inflammatory symptoms. These results support the proposal of developing interventions such as probiotics based on commensal bacteria with α-Gal epitopes to modify the microbiota and increase α-Gal-induced protective immune response and reduce severity of COVID-19.

A dataset for the analysis of antibody response to glycan alpha-Gal in individuals with immune-mediated disorders.

Humans evolved by losing the capacity to synthesize the glycan Galα1-3Galß1-(3)4GlcNAc-R (α-Gal), which resulted in the development of a protective response mediated by anti-α-Gal IgM/IgG/IgA antibodies against pathogens containing this modification on membrane proteins. As an evolutionary trade-off, humans can develop the alpha-Gal syndrome (AGS), a recently diagnosed disease mediated by anti-α-Gal IgE antibodies and associated with allergic reactions to mammalian meat consumption and tick bites. However, the anti-α-Gal antibody response may be associated with other immune-mediated disorders such as those occurring in patients with COVID-19 and Guillain-Barré syndrome (GBS). Here, we provide a dataset (209 entries) on the IgE/IgM/IgG/IgA anti-α-Gal antibody response in healthy individuals and patients diagnosed with AGS, tick-borne allergies, GBS and COVID-19. The data allows correlative analyses of the anti-α-Gal antibody response with factors such as patient and clinical characteristics, record of tick bites, blood group, age and sex. These analyses could provide insights into the role of anti-α-Gal antibody response in disease symptomatology and possible protective mechanisms.

Enhanced HLA-DR expression on T-lymphocytes from patients in early stages of non-surgical sepsis.

INTRODUCTION: Early detection of sepsis is a critical step to improve patient's survival and cellular markers effective diagnosis tools. The aim of this work was to evaluate HLA-DR expression on peripheral T-lymphocytes (CD3+), a marker associate to T-cell activation, as an early sepsis detection tool. PATIENTS AND METHODS: A cross-sectional study was conducted in twenty-six patients with confirmed sepsis by blood culture, eighteen healthy individuals and four patients with systemic inflammatory response syndrome. The analysis of the HLA-DR expression was carried by flow cytometry. RESULTS: The patients with confirmed sepsis had significantly higher percentage of CD3+/HLA-DR+ lymphocytes compared with both, patients with SIRS (20.37±9.42 vs. 8.7±2.9; p<0.005) and healthy individuals (20.37±9.42 vs. 6.58±3.89; p<0.005). Moreover, the average amount of HLA-DR expressed was higher when caused by gram-positive than by gram-negative bacterias (216.61±131.35 vs. 135.05±31.82; p=0.041). A ROC curve analysis showed the utility of HLA-DR expression on T-cells to identify patients with sepsis. DISCUSSION: Our results suggest that surface expression of HLA-DR on T-lymphocytes could be an early marker for the presence of sepsis in non-surgical septic patients.

Usefulness of basophil activation test for the diagnosis of IgE mediated hypersensitivity to tetanus toxoid vaccine.

A great number of vaccinated patients develop specific anti-tetanus toxoid IgE, but usually do not undergo any adverse effect. Most of the allergic reactions to tetanus toxoid vaccine usually present with unspecific symptoms of local inflammation. In the presence of severe reactions, and in a special way if the vaccine is provided together with other drugs, it is difficult to establish which is the harmful drug responsible for IgE-mediated adverse reaction. A patient with an anaphylactic reaction after the administration of Toxoid Tetanic (TT) along with several drugs is described. All skin test were negative. The basophils activation test (BAT) in a clear way, identified TT as the allergen that triggered anaphylaxis. The results achieved demonstrates the usefulness of BAT to clarify patients with hypersensibility to tetanus toxoide when the clinic is severe and the vaccine has been administered together with other drugs.