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By May 2021, >150 million severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and >3 million deaths from coronavirus disease (COVID-19) had been reported worldwide (1). The real infection count [...]

* Context.--Emerging evidence shows correlation between the presence of neutralization antibodies (nAbs) and protective immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Currently available commercial serology assays lack the ability to specifically identify nAbs. An enzyme-linked immunosorbent assay-based nAb assay (GenScript cPass neutralization antibody assay) has recently received emergency use authorization from the Food and Drug Administration. Objective.--To evaluate the performance characteristics of this assay and compare and correlate it with the commercial assays that detect SARS-CoV-2-specific immunoglobulin G (IgG). Design.--Specimens from SARS-COV-2 infected patients (n = 124), healthy donors obtained prepandemic (n = 100), and patients with non-coronavirus disease 2019 (COVID-19) respiratory infections (n = 92) were analyzed using this assay. Samples with residual volume were also tested on 3 commercial serology platforms (Abbott, Euroimmun, Siemens). Twenty-eight randomly selected specimens from patients with COVID-19 and 10 healthy controls were subjected to a plaque reduction neutralization test. Results.--The cPass assay exhibited 96.1% (95% CI, 94.9%-97.3%) sensitivity (at PCR), 100% (95% CI, 98.0%-100.0%) specificity, and zero cross-reactivity for the presence of non-COVID-19 respiratory infections. When compared with the plaque reduction assay, 97.4% (95% CI, 96.2%-98.5%) qualitative agreement and a positive correlation ([R.sup.2] = 0.76) was observed. Comparison of IgG signals from each of the commercial assays with the nAb results from plaque reduction neutralization test/cPass assays displayed greater than 94.7% qualitative agreement and correlations with [R.sup.2] = 0.43/0.68 (Abbott), [R.sup.2] = 0.57/0.85 (Euroimmun), and [R.sup.2] = 0.39/0.63 (Siemens), respectively. Conclusions.--The combined data support the use of cPass assay for accurate detection of the nAb response. Positive IgG results from commercial assays associated reasonably with nAbs presence and can serve as a substitute. doi: 10.5858/arpa.2021-0213-SA, With the availability of vaccines against the highly pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and as the pressure to reopen the economy increases, the demand for coronavirus disease [...]

Context.--Serum tests used for the screening and diagnosis of monoclonal gammopathies include serum protein electrophoresis (SPE; agarose gel or capillary zone), immunofixation (IFE) and immunosubtraction capillary electrophoresis, serum free light chains, quantitative immunoglobulins, and heavy/light-chain combinations. Urine protein electrophoresis and urine IFE may also be used to identify Bence-Jones proteinuria. Objective.--To assess current laboratory practice for monoclonal gammopathy testing. Design.--In April 2016, a voluntary questionnaire was distributed to 923 laboratories participating in a protein electrophoresis proficiency testing survey. Results.--Seven hundred seventy-four laboratories from 38 countries and regions completed the questionnaire (83.9% response rate; 774 of 923). The majority of participants (68.6%; 520 of 758) used agarose gel electrophoresis as their SPE method, whereas 31.4% (238 of 758) used capillary zone electrophoresis. The most common test approaches used in screening were SPE with reflex to IFE/immunosubtraction capillary electrophoresis (39.3%; 299 of 760); SPE only (19.1%; 145 of 760); SPE and IFE or immunosubtraction capillary electrophoresis (13.9%; 106 of 760); and SPE with IFE, serum free light chain, and quantitative immunoglobulins (11.8%; 90 of 760). Only 39.8% (305 of 767) of laboratories offered panel testing for ordering convenience. Although SPE was used by most laboratories in diagnosing new cases of myeloma, when laboratories reported the primary test used to follow patients with monoclonal gammopathy, only 55.7% (403 of 724) chose SPE, with the next most common selections being IFE (18.9%; 137 of 724), serum free light chain (11.7%; 85 of 724), and immunosubtraction capillary electrophoresis (2.1%; 15 of 724). Conclusions.--Ordering and testing practices for the screening and diagnosis of monoclonal gammopathy vary widely across laboratories. Improving utilization management and report content, as well as recognition and development of laboratory-directed testing guidelines, may serve to enhance the clinical value of testing. doi: 10.5858/arpa.2017-0128-CP, Monoclonal gammopathies are hematologic disorders characterized by abnormal production of one or more immunoglobulin clones. (1) They range from asymptomatic, benign disorders (such as monoclonal gammopathy of undetermined significance) to [...]

Background: Numerous serology assays are available for detection of SARS-CoV-2 antibodies but are limited in that only 1 or 2 target antigen(s) can be tested at a time. Here, we describe a novel multiplex assay that simultaneously detects and quantifies IgG antibodies to SARS-CoV-2 antigens, spike (S), nucleocapsid (N), receptor-binding domain (RBD), and N-terminal domain (NTD) in a single well. Methods: Sensitivity was determined using samples (n = 124) from confirmed SARS-CoV-2 RT-PCR positive individuals. Prepandemic (n = 100) and non-COVID respiratory infection positive samples (n = 100) were used to evaluate specificity. Samples were analyzed using COVID-19 IgG multiplex serology assay from Meso Scale Discovery (MSD) and using commercial platforms from Abbott, EUROIMMUN, and Siemens. Results: At >14 days post-PCR, MSD assay displayed >98.0% sensitivity [S 100% (95% CI 98.0%–100.0%); N 98.0% (95% CI 97.2%–98.9%); RBD 94.1% (95% CI 92.6%–95.6%); NTD 98.0% (95% CI, 97.2%–98.9%)] and 99% specificity (95% CI 99.3%–99.7%) for antibodies to all 4 antigens. Parallel assessment of antibodies to more than 1 antigen improved the sensitivity to 100% (95% CI 98.0%–100.0%) while maintaining 98% (95% CI 97.6%–98.4%) specificity regardless of the combinations used. When AU/mL concentrations of IgG antibodies from the MSD assay were compared against the corresponding IgG signals acquired from the single target commercial assays, the following correlations were observed: Abbott (vs MSD N, R2 = 0.73), Siemens (vs MSD RBD, R2 = 0.92), and EUROIMMUN (vs MSD S, R2 = 0.82). Conclusion: MSD assay offers an accurate and a comprehensive assessment of SARS-CoV-2 antibodies with higher sensitivity and equivalent specificity compared to the commercial IgG serology assays. [ABSTRACT FROM AUTHOR]