Longitudinal assessment of SARS-CoV-2 nucleocapsid antigenemia in patients hospitalized with COVID-19

Abstract While RT-PCR tests of nasopharyngeal swabs remain the gold standard for the detection of SARS-CoV-2 infection and monitoring of COVID-19 disease progression, measurement of nucleocapsid antigenemia in serum and plasma samples is an underexplored alternative proxy for disease severity. To explore the dynamics of nucleocapsid antigenemia, we measured levels of nucleocapsid antigen using a highly sensitive Single Molecule Array (Simoa) assay in 817 serially collected serum and plasma samples from 93 PCR-confirmed COVID-19 patients for whom symptom onset date could be extracted by chart review. In a subset of these individuals (n=13), we measured seroconversion by titering for receptor binding domain (RBD) specific IgG, IgA, and IgM. A model of exponential decay was fit to data from individuals with high resolution daily sampling (N=34), from which the half-life of SARS-CoV-2 nucleocapsid in serum was determined. Mean nucleocapsid half-life in this group of patients was 1.17 days (SD=0.82). Nucleocapsid levels were significantly higher in the first 10 days following symptom onset in patients who died compared to those with a milder disease course (p=0.004). Further, mortality was associated with a trend toward longer nucleocapsid half-life (1.51 days vs. 0.79 days) (p=0.10). In patients who had both antibody and antigenemia data available, antibody response was temporally linked to antigen decay, reaching peak levels as antigen was cleared from the blood. Our data identify SARS-CoV-2 nucleocapsid antigenemia as a potential diagnostic tool for acute COVID-19 disease and an early biomarker associated with disease severity.

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Dimeric IgA is a specific biomarker of recent SARS-CoV-2 infection

10.1101/2021.06.28.21259671 ◽

2021 ◽

Author(s):

Heidi E Drummer ◽

Huy Van ◽

Ethan Klock ◽

Shuning Zheng ◽

Zihui Wei ◽

...

Keyword(s):

Receptor Binding ◽

Symptom Onset ◽

Colloidal Gold ◽

Half Life ◽

Point Of Care ◽

Secretory Component ◽

Receptor Binding Domain ◽

Plasma Samples ◽

Cross Sectional ◽

Negative Patient

Current tests for SARS-CoV-2 antibodies (IgG, IgM, IgA) cannot differentiate recent and past infections. We describe a point of care, lateral flow assay for SARS-CoV-2 dIgA based on the highly selective binding of dIgA to a chimeric form of secretory component (CSC), that distinguishes dIgA from monomeric IgA. Detection of specific dIgA uses a complex of biotinylated SARS-CoV-2 receptor binding domain and streptavidin-colloidal gold. SARS-CoV-2-specific dIgA was measured both in 112 cross-sectional samples and a longitudinal panel of 362 plasma samples from 45 patients with PCR-confirmed SARS-CoV-2 infection, and 193 discrete pre-COVID-19 or PCR-negative patient samples. The assay demonstrated 100% sensitivity from 11 days post-symptom onset, and a specificity of 98.2%. With an estimated half-life of 6.3 days, dIgA provides a unique biomarker for the detection of recent SARS-CoV-2 infections with potential to enhance diagnosis and management of COVID-19 at point-of-care.

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Serial Profiling of SARS-CoV-2 Antigens and Antibodies in COVID-19 Patient Plasma

10.1101/2020.07.20.20156372 ◽

2020 ◽

Author(s):

Alana F Ogata ◽

Adam M Maley ◽

Connie Wu ◽

Tal Gilboa ◽

Maia Norman ◽

...

Keyword(s):

Severe Acute Respiratory Syndrome ◽

Disease Severity ◽

Single Molecule ◽

Gold Standard ◽

Viral Antigen ◽

Plasma Samples ◽

Viral Antigens ◽

Antigen Tests

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected millions of people worldwide. PCR tests are currently the gold standard for diagnosis of the current coronavirus disease (COVID-19) and serology tests are used to detect seroconversion in infected patients. However, there is a lack of quantitative and ultra-sensitive viral antigen tests for COVID-19. Here we show that Single Molecule Array (Simoa) assays can quantitatively detect SARS-CoV-2 spike, S1 subunit, and nucleocapsid antigens in the plasma of COVID-19 patients. Combined with Simoa anti-SARS-CoV-2 serological assays, we show correlation between production of antibodies and clearance of viral antigens from serial plasma samples from COVID-19 patients. Furthermore, we demonstrate the presence of viral antigens in blood correlates with disease severity in hospitalized COVID-19 patients. These data suggest that SARS-CoV-2 viral antigens in the blood could be a marker for severe COVID-19 cases.

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Nonconcordance of E, N, and RdRp Genes in SARS-Coronavirus-2 Nucleic Acid Amplification Test Among Patients Older than 60 Years

American Journal of Clinical Pathology ◽

10.1093/ajcp/aqaa161.277 ◽

2020 ◽

Vol 154 (Supplement_1) ◽

pp. S126-S127

Author(s):

H Caulkins ◽

K Rand ◽

N Harris ◽

S Beal

Keyword(s):

Nucleic Acid ◽

Symptom Onset ◽

Chart Review ◽

Nucleic Acid Amplification ◽

Onset Date ◽

Sars Coronavirus ◽

Future Directions ◽

Systematic Processing ◽

At Risk Populations ◽

Processing Errors

Abstract Introduction/Objective During the COVID-19 pandemic, the FDA authorized emergency use of nucleic acid amplification (NAA) testing. Accurate and rapid testing identifies infected persons, especially among at-risk populations. In our institution, the InGenius platform detects three gene targets of SARS-Coronavirus-2: envelope (E), nucleocapsid (N), and RNA-dependent RNA polymerase (RdRp). Nonconcordance of these components present accuracy or precision errors or may correspond to varying expression of viral genes with disease progression. Methods We retrospectively analyzed the result components from 93 nasopharyngeal swabs from 50 patients older than 60 years and positive for SARS-Coronavirus-2 (SARS-CoV-2). The symptom onset date was determined by chart review. Results We found a significant 26% nonconcordance rate, with a predominant pattern demonstrating positive N with negative RdRp and E (χ2 = 27.25, P < 0.0005). This nonconcordant pattern was more prevalent at longer symptom durations. In 7 patients with serial testing, the transition from concordant to nonconcordant results occurred 12 days (95% CI 3.5 – 20.3 days) after symptom onset. Conclusion This may be caused by several mechanisms. Possibilities include decreased expression of E and RdRp over time, inhibition of expression by treatments or host immune response, or lower viral titers by clearance or migration to the lower respiratory tract. Presence of a different viral strain or systematic processing errors are less likely causes of nonconcordance. Future directions of study would determine whether a similar decline in RdRp and E detection is seen in tracheal samples or if this correlates with changes in symptom severity.

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FVIII-binding IgG modulates FVIII half-life in patients with severe and moderate hemophilia A without inhibitors

Blood ◽

10.1182/blood-2015-10-675512 ◽

2016 ◽

Vol 128 (2) ◽

pp. 293-296 ◽

Cited By ~ 16

Author(s):

Christoph J. Hofbauer ◽

Sylvia Kepa ◽

Michael Schemper ◽

Peter Quehenberger ◽

Sylvia Reitter-Pfoertner ◽

...

Keyword(s):

Half Life ◽

Hemophilia A ◽

Igg Antibodies ◽

Key Points ◽

Specific Igg ◽

Specific Igg Antibodies

Key Points FVIII-specific IgG antibodies modulate FVIII half-life in patients with hemophilia A, independent of VWF antigen levels and age. Screening for FVIII-specific IgG may be beneficial in tailoring FVIII prophylactic regimens for hemophilia A patients.

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Serum glial fibrillary acidic protein correlates with multiple sclerosis disease severity

Multiple Sclerosis Journal ◽

10.1177/1352458518819380 ◽

2018 ◽

Vol 26 (2) ◽

pp. 210-219 ◽

Cited By ~ 16

Author(s):

Heidi Högel ◽

Eero Rissanen ◽

Christian Barro ◽

Markus Matilainen ◽

Marjo Nylund ◽

...

Keyword(s):

Multiple Sclerosis ◽

Nervous System ◽

Glial Fibrillary Acidic Protein ◽

Disease Progression ◽

Disease Severity ◽

Single Molecule ◽

Progressive Disease ◽

Disease Duration ◽

Acidic Protein ◽

Csf Levels

Background: Cerebrospinal fluid (CSF) levels of two soluble biomarkers, glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL), have been shown to associate with multiple sclerosis (MS) disease progression. Now, both biomarkers can be detected reliably in serum, and importantly, their serum levels correlate well with their CSF levels. Objective: To evaluate the usability of serum GFAP measurement as a biomarker of progressive disease and disease severity in MS. Methods: Clinical course, Expanded Disability Status Scale (EDSS), disease duration, patient age and magnetic resonance imaging (MRI) parameters were reviewed in 79 MS patients in this cross-sectional hospital-based study. Serum samples were collected for measurement of GFAP and NfL concentrations using single molecule array (Simoa) assay. A cohort of healthy controls was evaluated for comparison. Results: Higher serum concentrations of both GFAP and NfL were associated with higher EDSS, older age, longer disease duration, progressive disease course and MRI pathology. Conclusion: Earlier studies have demonstrated that GFAP, unlike NfL, is not increased in association with acute focal inflammation-related nervous system damage. Our work suggests that GFAP serum level associates with disease progression in MS and could potentially serve as an easily measurable biomarker of central nervous system (CNS) pathology related to disease progression in MS.

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Declining Levels of Neutralizing Antibodies Against SARS-CoV-2 in Convalescent COVID-19 Patients One Year Post Symptom Onset

Frontiers in Immunology ◽

10.3389/fimmu.2021.708523 ◽

2021 ◽

Vol 12 ◽

Author(s):

Tiandan Xiang ◽

Boyun Liang ◽

Yaohui Fang ◽

Sihong Lu ◽

Sumeng Li ◽

...

Keyword(s):

Symptom Onset ◽

Neutralizing Antibodies ◽

Natural Infection ◽

Protein S ◽

Igg Antibodies ◽

Neutralizing Activity ◽

Specific Igg ◽

One Year ◽

Kinetics Of

Major advances have been made in understanding the dynamics of humoral immunity briefly after the acute coronavirus disease 2019 (COVID-19). However, knowledge concerning long-term kinetics of antibody responses in convalescent patients is limited. During a one-year period post symptom onset, we longitudinally collected 162 samples from 76 patients and quantified IgM and IgG antibodies recognizing the nucleocapsid (N) protein or the receptor binding domain (RBD) of the spike protein (S). After one year, approximately 90% of recovered patients still had detectable SARS-CoV-2-specific IgG antibodies recognizing N and RBD-S. Intriguingly, neutralizing activity was only detectable in ~43% of patients. When neutralization tests against the E484K-mutated variant of concern (VOC) B.1.351 (initially identified in South Africa) were performed among patients who neutralize the original virus, the capacity to neutralize was even further diminished to 22.6% of donors. Despite declining N- and S-specific IgG titers, a considerable fraction of recovered patients had detectable neutralizing activity one year after infection. However, neutralizing capacities, in particular against an E484K-mutated VOC were only detectable in a minority of patients one year after symptomatic COVID-19. Our findings shed light on the kinetics of long-term immune responses after natural SARS-CoV-2 infection and argue for vaccinations of individuals who experienced a natural infection to protect against emerging VOC.

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The Characterization of Disease Severity Associated IgG Subclasses Response in COVID-19 Patients

Frontiers in Immunology ◽

10.3389/fimmu.2021.632814 ◽

2021 ◽

Vol 12 ◽

Author(s):

Huanle Luo ◽

Tingting Jia ◽

Jiamin Chen ◽

Shike Zeng ◽

Zengzhao Qiu ◽

...

Keyword(s):

Viral Load ◽

Disease Severity ◽

Young Patients ◽

Neutralizing Antibody ◽

Igg Subclasses ◽

Nasopharyngeal Swab ◽

Obvious Effect ◽

Old Patients ◽

Biological Sex ◽

Specific Igg

Increasing evidence suggests that dysregulated immune responses are associated with the clinical outcome of coronavirus disease 2019 (COVID-19). Nucleocapsid protein (NP)-, spike (S)-, receptor binding domain (RBD)- specific immunoglobulin (Ig) isotypes, IgG subclasses and neutralizing antibody (NAb) were analyzed in 123 serum from 63 hospitalized patients with severe, moderate, mild or asymptomatic COVID-19. Mild to modest correlations were found between disease severity and antigen specific IgG subclasses in serum, of which IgG1 and IgG3 were negatively associated with viral load in nasopharyngeal swab. Multiple cytokines were significantly related with antigen-specific Ig isotypes and IgG subclasses, and IL-1β was positively correlated with most antibodies. Furthermore, the old patients (≥ 60 years old) had higher levels of chemokines, increased NAb activities and SARS-CoV-2 specific IgG1, and IgG3 responses and compromised T cell responses compared to the young patients (≤ 18 years old), which are related with more severe cases. Higher IgG1 and IgG3 were found in COVID-19 patients with comorbidities while biological sex had no effect on IgG subclasses. Overall, we have identified diseases severity was related to higher antibodies, of which IgG subclasses had weakly negative correlation with viral load, and cytokines were significantly associated with antibody response. Further, advancing age and comorbidities had obvious effect on IgG1 and IgG3.

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2356. Increased Clinical Specificity with Ultrasensitive Detection of Clostridioides difficile Toxins: Reduction of Overdiagnosis Compared with Nucleic Acid Amplification Tests

Open Forum Infectious Diseases ◽

10.1093/ofid/ofz360.2034 ◽

2019 ◽

Vol 6 (Supplement_2) ◽

pp. S811-S812 ◽

Cited By ~ 1

Author(s):

Johanna Sandlund ◽

Joel Estis ◽

Phoebe Katzenbach ◽

Niamh Nolan ◽

Kirstie Hinson ◽

...

Keyword(s):

Nucleic Acid ◽

Disease Severity ◽

Single Molecule ◽

Clinical Performance ◽

Neutralization Assay ◽

Nucleic Acid Amplification ◽

Clostridioides Difficile ◽

Percent Agreement ◽

Clostridioides Difficile Infection ◽

Healthcare Associated

Abstract Background Clostridioides difficile infection (CDI) is one of the most common healthcare-associated infections, resulting in significant morbidity, mortality, and economic burden. Diagnosis of CDI relies on the assessment of clinical presentation and laboratory tests. We have evaluated the clinical performance of ultrasensitive Single Molecule Counting technology for detection of C. difficile toxins A and B. Methods Stool specimens from 298 patients with suspected CDI were tested with nucleic acid amplification test (NAAT; BD MAX™ Cdiff assay or Xpert® C. difficile assay) and Singulex Clarity® C. difficile toxins A/B assay. Specimens with discordant results were tested with cell cytotoxicity neutralization assay (CCNA), and results were correlated with disease severity and outcome. Results There were 64 NAAT-positive and 234 NAAT-negative samples. Of the 32 NAAT+/Clarity− and 4 NAAT-/Clarity+ samples, there were 26 CCNA− and 4 CCNA- samples, respectively. CDI relapse or overall death was more common in NAAT+/toxin+ patients than in NAAT+/toxin− and NAAT−/toxin− patients, and NAAT+/toxin+ patients were 3.7 times more likely to experience relapse or death (Figure 1). The clinical specificity of Clarity and NAAT was 97.4% and 89.0%, respectively, and overdiagnosis was over three times more common in NAAT+/toxin− than in NAAT+/toxin+ patients (Figure 2). Negative percent agreement between NAAT and Clarity was 98.3%, and positive percent agreement increased from 50.0% to effective 84.2% and 94.1% after CCNA testing and clinical assessment. Conclusion The Clarity assay was superior to NAATs in diagnosis of CDI, by reducing overdiagnosis and thereby increasing clinical specificity, and presence of toxins was associated with disease severity and outcome. Disclosures All authors: No reported disclosures.

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Association between incubation period and clinical characteristics of patients with COVID-19

Journal of International Medical Research ◽

10.1177/0300060520956834 ◽

2020 ◽

Vol 48 (9) ◽

pp. 030006052095683

Author(s):

Yeyu Cai ◽

Jiayi Liu ◽

Haitao Yang ◽

Mian Wang ◽

Qingping Guo ◽

...

Keyword(s):

Incubation Period ◽

Disease Severity ◽

Symptom Onset ◽

Clinical Characteristics ◽

Characteristic Curve ◽

Severe Disease ◽

Receiver Operator Characteristic Curve ◽

Hunan Province ◽

Laboratory Findings ◽

Incubation Periods

Purpose To investigate associations between the clinical characteristics and incubation periods of patients infected with coronavirus disease 2019 (COVID-19) in Wuhan, China. Methods Complete clinical and epidemiological data from 149 patients with COVID-19 at a hospital in Hunan Province, China, were collected and retrospectively analyzed. Results Analysis of the distribution and receiver operator characteristic curve of incubation periods showed that 7 days was the optimal cut-off value to assess differences in disease severity between groups. Patients with shorter (≤7 days) incubation periods (n = 79) had more severe disease, longer durations of hospitalization, longer times from symptom onset to discharge, more abnormal laboratory findings, and more severe radiological findings than patients with longer (>7 days) incubation periods. Regression and correlation analyses also showed that a shorter incubation period was associated with longer times from symptom onset to discharge. Conclusion The associations between the incubation periods and clinical characteristics of COVID-19 patients suggest that the incubation period may be a useful marker of disease severity and prognosis.

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Correlational Analysis of ALS Progression and Serum NfL Measured by Simoa Assay in Chinese Patients

Frontiers in Neurology ◽

10.3389/fneur.2020.579094 ◽

2020 ◽

Vol 11 ◽

Author(s):

Kazuo Sugimoto ◽

Yi Han ◽

Yuebo Song ◽

Ying Gao

Keyword(s):

Disease Severity ◽

Single Molecule ◽

Clinical Relevance ◽

Rating Scale ◽

Diagnostic Delay ◽

Chinese Patients ◽

Progression Rate ◽

Neurofilament Light Chain ◽

Potential Biomarker ◽

Als Patients

Background: Neurofilament light chain (NFL) was believed to be a promising biomarker for the diagnosis of Amyotrophic lateral sclerosis (ALS) and disease burden evaluation.Objective: To determine the serum NFL level and its clinical relevance, including its association with disease severity [evaluated by the ALS Functional Rating Scale–revised (ALSFRS-r) score and King's College staging system] and progression (evaluated by the disease progression rate (DPR) and diagnostic delay), in ALS patients in China.Method: Serum NFL levels were detected using the Single Molecule Array (Simoa) technology in 30 ALS patients and 20 healthy controls (HCs).Results: There were significantly elevated levels of serum NFL in patients with ALS than in the HCs (P < 0.001). The serum NFL levels were significantly higher in rapidly progressive ALS and patients in Stage 3 than in slowly progressive ALS and patients in Stage 2 (PDPR < 0.001, PDiagnosticdelay = 0.019; Pstage= 0.033). Furthermore, the serum NFL levels negatively correlated with the diagnostic delay (R2 = 0.23, P = 0.016), the ALSFRS-r score (R2 = 0.15, P = 0.047) and disease duration (R2 = 0.15, P = 0.034), and positively correlated with the DPR (R2 = 0.42, P < 0.001).Conclusions: The present study preliminarily investigated the diagnostic value of serum NFL and its clinical relevance in the Chinese ALS population using the ultrasensitive Simoa technology. The results demonstrated that the level of serum NFL may become a potential biomarker for ALS diagnosis and indicate disease severity and progression.

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