Viral and Immune Factors in Acute Respiratory Virus Infections: Evaluating the Role of SARS-CoV-2 Nucleocapsid Antigenemia in the Diagnosis and Pathogenesis of SARS-CoV-2 Infection Open Access
Verkerke, Hans (Summer 2022)
Published
Abstract
In the first months of the SARS-CoV-2 pandemic, we undertook several translational studies as part of the COVID-19 response at Emory to evaluate early biomarkers of disease severity and investigate the use of serological tests as adjunctive diagnostic tools. As part of these efforts, we aided in the development, validation, and implementation of the FDA authorized SARS-CoV-2 IgG test, still the primary serological test used in the Emory system for COVID-19. We then employed versions of this test in studies evaluating the antibody components of therapeutic COVID-19 convalescent plasma units, finding significant heterogeneity in levels of SARS-CoV-2 IgG, IgA, and IgM. Finally, we have spearheaded the development of novel, high-throughput testing platforms for SARS-CoV-2 neutralizing antibody activity, a primary correlate of vaccine efficacy and protection after natural infection.
While developing these tools, we conducted several clinical studies to uncover biomarkers of COVID-19 severity. In these studies, we found that viral nucleocapsid antigenemia could reliably be measured in blood samples taken during the acute phase of infection. This observation led us to test whether nucleocapsid antigenemia may be a specific diagnostic biomarker of acute SARS-CoV-2 infection. To this end, we conducted a large retrospective serological survey of COVID-19 patients, quantifying antigenemia in 1860 specimens from 1607 patients. In this cohort, antigenemia exhibited 85.8% sensitivity and 98.6% specificity in diagnosing acute COVID-19 cases, suggesting its possible utility as a screening tool for SARS-CoV-2 infection in blood samples.
Infection with SARS-CoV-2 results in a broad spectrum of clinical manifestations from asymptomatic carriage to severe respiratory failure and death. Notably, many patients with severe COVID-19 suffer from systemic disease involving microvascular inflammation, thromboembolism, and multi-system organ failure. However, the viral and immune factors driving these complications remain incompletely understood. Our work on viral antigenemia as a diagnostic tool led us to also evaluate its utility as a prognostic biomarker and potential driver of systemic pathology. We found that early nucleocapsid antigenemia levels predict disease severity and mortality and are associated with specific patterns of antiviral cytokine response. Furthermore, SARS-CoV-2 nucleocapsid itself can stimulate endothelial cells to elicit antiviral cytokine secretion and upregulation of leukocyte adhesion molecules. Together these studies provide a novel framework for understanding nucleocapsid antigenemia as both a diagnostic marker of acute infection and a clinical biomarker of severe COVID-19 that may itself contribute to endothelial dysfunction and systemic disease.
Table of Contents
Table of Contents
Chapter 1 SARS-CoV-2 diagnosis and pathogenesis
Abstract
SARS-CoV-2 Diagnostics
Detection of SARS-CoV-2 Infection
SARS-CoV-2 Infection and infectiousness
Viral Life Cycle
Spike Protein
Nucleocapsid Protein
Membrane
Envelope
Accessory Proteins
Pathogenesis
Innate Response
Adaptive Response
Humoral Response
Autoantibody formation
Cytokine storm
COVID-19 Coagulopathy
Conclusions and outlook
Thesis Objectives
Figures for Chapter 1
Chapter 2 Nucleocapsid Antigenemia in the diagnosis of SARS-CoV-2 Infection
Abstract
Introduction
Results
Discussion
Experimental Procedures
Author Contributions
Tables Chapter 2
Figures Chapter 2
Chapter 3
Abstract
Introduction
Results
Discussion
Experimental Methods
Chapter 3 Tables
Figures for Chapter 3
Chapter 4 SARS-CoV-2 antibody class-specific serology: applications in diagnostics and characterization of COVID-19 convalescent plasma
Abstract
Introduction
Results
Discussion
Experimental Methods
Chapter 4 Tables
Chapter 4 Figures
Chapter 5 Rapid, automated detection of SARS-CoV-2 neutralizing antibodies against native-like vaccine and delta variant spike trimers
Abstract
Introduction
Results
Discussion
Experimental Methods
Figures for Chapter 5
Chapter 6 Conclusions and Outlook
SARS-CoV-2 Serological Tests: Then and Now
Viral antigenemia: Implications for diagnosis
Viral Antigenemia: implications for COVID-19 pathology
Appendix 1 Supplementary materials to Chapter 2
Supplementary Experimental Methods
Supplementary Figures and Tables
Appendix 2 Galectins, An Ancient Family of Carbohydrate Binding Proteins with Modern Functions
Abstract
Introduction
The Evolution of Carbohydrate Recognition
Galectin Evolution and Biochemistry
Galectin Evolution
The Galectin CRD
Synthesis of Galectin Carbohydrate Ligands
Mammalian Galectin Expression and Localization
Nuclear and Cytoplasmic Galectins
Galectin Secretion
Modern Galectin Functions
Regulation of Pre-mRNA Splicing and mRNA Stability
Intracellular Signaling: Proliferation and Apoptosis
The Galectin Lattice
Homeostasis
Cancer
Roles in the Mammalian Immune System
Engagement and Crosslinking of Surface Receptors
Regulation of Immune Cell Turnover
Modulation of Inflammatory Intracellular Signaling Pathways
Intracellular Pattern Recognition and Damage Sensing
Galectin-Pathogen Interactions
Summary and Conclusions
Appendix 3 Evaluating the Role of Galectin-1 during Influenza A Virus Infection
Abstract
Introduction
Results
Conclusion
Experimental Procedures
Figures for Appendix 3
References
*Author contributions are included in chapters that include co-first authored materials
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