Measurement of SARS-CoV-2 antigens in plasma of pediatric patients with acute COVID-19 or MIS-C using an ultrasensitive and quantitative immunoassay

Sigal, George B.; Novak, Tanya; Mathew, Anu; Chou, Janet; Zhang, Yubo; Manjula, Navaratnam; Bathala, Predeepthi; Joe, Jessica; Padmanabhan, Nikhil; Romero, Daniel; Allegri-Machado, Gabriella; Joerger, Jill; Loftis, Laura; Schwartz, Stephanie P; Walker, Tracie C; Fitzgerald, Julie C; Tarquinio, Keiko M.; Zinter, Matt S; Schuster, Jennifer E; Halasa, Natasha; Cullimore, Melissa L; Maddux, Aline B; Staat, Mary Allen; Irby, Katherine; Flori, Heidi R.; Coates, Bria M.; Crandall, Hillary; Gertz, Shira J.; Randolph, Adrienne G.; Pollock, Nira R.

doi:10.1101/2021.12.08.21267502

Cited by 7 publications

(9 citation statements)

References 13 publications

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“…As anticipated, a higher N antigen concentration was observed per GE in comparison to S antigen concentration, which has also been shown in plasma. 17,18 These results support the focus on N antigen for RDTs and overall correlation of antigen concentration with genome copy number 9,19,20 .…”

Section: Discussionsupporting

confidence: 72%

A Reagent and Virus Benchmarking Panel for a Uniform Analytical Performance Assessment of N Antigen–Based Diagnostic Tests for COVID-19

Golden

Cantera

Lillis

et al. 2022

Preprint

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Rapid diagnostic tests (RDTs) that detect antigen indicative of SARS-CoV-2 infection can help in making quick health care decisions and regularly monitoring groups at risk of infection. With many RDT products entering the market, it is important to rapidly evaluate their relative performance. Comparison of clinical evaluation study results is challenged by protocol design variations and study populations. Laboratory assays were developed to quantify nucleocapsid (N) and spike (S) SARS-CoV-2 antigens. Quantification of the two antigens in nasal eluates confirmed higher abundance of N than S antigen. The median concentration of N antigen was 10 times greater than S per genome equivalent. The N antigen assay was used in combination with quantitative RT-PCR to qualify a panel composed of recombinant antigens, inactivated virus, and clinical specimen pools. This benchmarking panel was applied to evaluate the analytical performance of the SD Biosensor STANDARD Q COVID-19 Ag test, Abbott Panbio COVID-19 Ag Rapid Test, Abbott BinaxNOW COVID-19 Ag test, and the LumiraDx SARS-CoV-2 Ag Test. The four tests displayed different sensitivities toward the different panel members, but all performed best with the clinical specimen pool. The concentration for a 90% probability of detection across the four tests ranged from 21 pg/mL to 102 pg/mL of N antigen in the extracted sample. Benchmarking panels provide a quick way to verify the baseline performance of a diagnostic and enable direct comparison between diagnostic tests.

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Section: Discussionsupporting

confidence: 72%

A Reagent and Virus Benchmarking Panel for a Uniform Analytical Performance Assessment of N Antigen–Based Diagnostic Tests for COVID-19

Golden

Cantera

Lillis

et al. 2022

Preprint

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“…A recent study demonstrated that persistence of SARS-CoV-2 in the gastrointestinal tracts of patients with MIS-C was associated with a breakdown of mucosal integrity and subsequent spike protein antigenemia and hyperinflammation [ 27 ]. While this explanation could correspond with the prominent gastrointestinal symptoms observed in MIS-C, the finding of SARS-CoV-2 antigenemia has not been universal [ 28 ]. The reasons why antigenemia may trigger delayed but not acute systemic hyperinflammation are similarly unclear.…”

Section: Discussionmentioning

confidence: 99%

Serologic and Cytokine Signatures in Children With Multisystem Inflammatory Syndrome and Coronavirus Disease 2019

Lapp

Abrams

et al. 2022

Open Forum Infectious Diseases

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Background The serologic and cytokine responses of children hospitalized with multisystem inflammatory syndrome (MIS-C) vs. COVID-19 are poorly understood. Methods We performed a prospective, multicenter, cross-sectional study of hospitalized children who met the CDC case definition for MIS-C (n=118), acute COVID-19 (n=88), or contemporaneous healthy controls (n=24). We measured SARS-CoV-2 spike receptor binding domain (RBD) IgG titers and cytokine concentrations in patients and performed multivariable analysis to determine cytokine signatures associated with MIS-C. We also measured nucleocapsid IgG and convalescent RBD IgG in subsets of patients. Results Children with MIS-C had significantly higher SARS-CoV-2 RBD IgG than children with acute COVID-19 (median 2783 vs. 146, P<0.001), and titers correlated with nucleocapsid IgG. For patients with MIS-C, RBD IgG titers declined in convalescence (median 2783 vs. 1135, P=0.010) in contrast to patients with COVID-19 (146 vs. 4795, P<0.001). MIS-C was characterized by transient acute pro-inflammatory hypercytokinemia, including elevated levels of IL-6, IL-10, IL-17A, and IFN-γ. Elevation of at least 3 of these cytokines was associated with significantly increased prevalence of prolonged hospitalization ≥8 days (PR 3.29 95% CI 1.17-9.23). Conclusions MIS-C was associated with high titers of SARS-COV-2 RBD IgG antibodies and acute hypercytokinemia with IL-6, IL-10, IL-17A, and IFN-γ.

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“…There is increasing interest in the utility of the detection of viral protein antigens in the blood, which are detectable within 2 weeks of symptom onset [27][28][29][30] and are quantifiable even in patients with mild or minimal symptoms [28][29][30][31]. However, there are currently limited studies of how SARS-CoV-2 viral antigen detection in the blood is related to disease severity and outcomes [32][33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Plasma SARS-CoV-2 nucleocapsid antigen levels are associated with progression to severe disease in hospitalized COVID-19

et al. 2022

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Background Studies quantifying SARS-CoV-2 have focused on upper respiratory tract or plasma viral RNA with inconsistent association with clinical outcomes. The association between plasma viral antigen levels and clinical outcomes has not been previously studied. Our aim was to investigate the relationship between plasma SARS-CoV-2 nucleocapsid antigen (N-antigen) concentration and both markers of host response and clinical outcomes. Methods SARS-CoV-2 N-antigen concentrations were measured in the first study plasma sample (D0), collected within 72 h of hospital admission, from 256 subjects admitted between March 2020 and August 2021 in a prospective observational cohort of hospitalized patients with COVID-19. The rank correlations between plasma N-antigen and plasma biomarkers of tissue damage, coagulation, and inflammation were assessed. Multiple ordinal regression was used to test the association between enrollment N-antigen plasma concentration and the primary outcome of clinical deterioration at one week as measured by a modified World Health Organization (WHO) ordinal scale. Multiple logistic regression was used to test the association between enrollment plasma N-antigen concentration and the secondary outcomes of ICU admission, mechanical ventilation at 28 days, and death at 28 days. The prognostic discrimination of an externally derived “high antigen” cutoff of N-antigen ≥ 1000 pg/mL was also tested. Results N-antigen on D0 was detectable in 84% of study participants. Plasma N-antigen levels significantly correlated with RAGE (r = 0.61), IL-10 (r = 0.59), and IP-10 (r = 0.59, adjusted p = 0.01 for all correlations). For the primary outcome of clinical status at one week, each 500 pg/mL increase in plasma N-antigen level was associated with an adjusted OR of 1.05 (95% CI 1.03–1.08) for worse WHO ordinal status. D0 plasma N-antigen ≥ 1000 pg/mL was 77% sensitive and 59% specific (AUROC 0.68) with a positive predictive value of 23% and a negative predictive value of 93% for a worse WHO ordinal scale at day 7 compared to baseline. D0 N-antigen concentration was independently associated with ICU admission and 28-day mechanical ventilation, but not with death at 28 days. Conclusions Plasma N-antigen levels are readily measured and provide important insight into the pathogenesis and prognosis of COVID-19. The measurement of N-antigen levels early in-hospital course may improve risk stratification, especially for identifying patients who are unlikely to progress to severe disease.

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Measurement of SARS-CoV-2 antigens in plasma of pediatric patients with acute COVID-19 or MIS-C using an ultrasensitive and quantitative immunoassay

Cited by 7 publications

References 13 publications

A Reagent and Virus Benchmarking Panel for a Uniform Analytical Performance Assessment of N Antigen–Based Diagnostic Tests for COVID-19

A Reagent and Virus Benchmarking Panel for a Uniform Analytical Performance Assessment of N Antigen–Based Diagnostic Tests for COVID-19

Serologic and Cytokine Signatures in Children With Multisystem Inflammatory Syndrome and Coronavirus Disease 2019

Plasma SARS-CoV-2 nucleocapsid antigen levels are associated with progression to severe disease in hospitalized COVID-19

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