Validation of a multiplex flow immunoassay for detection of IgG antibodies against SARS-CoV-2 in dried blood spots.

Background: Dried blood spots (DBS) are an established specimen type for clinical testing given their low cost, ease of collection and storage, and convenient shipping capabilities through the postal system. These attributes are complementary to the expansion of SARS-CoV-2 serologic testing, which may be used to inform community seroprevalence rates.

Methods: The Luminex xMAP SARS-CoV-2 Multi-Antigen assay utilizes magnetic beads labeled with three viral antigens (nucleocapsid [NC], receptor binding domain [RBD], spike S1 subunit) to detect anti-viral IgG-class antibodies, and has Food and Drug Administration (FDA) Emergency Use Authorization (EUA) for use in serum and plasma.

Performance Characteristics of Four High-Throughput Immunoassays for Detection of IgG Antibodies against SARS-CoV-2.

The role of serologic testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in both the clinical and public health settings, will continue to evolve as we gain increasing insight into our immune response to the virus. Here, we evaluated four high-throughput serologic tests for detection of anti-SARS-CoV-2 IgG antibodies, from Abbott Laboratories (Abbott Park, IL), Epitope Diagnostics, Inc. (San Diego, CA), Euroimmun (Lubeck, Germany), and Ortho-Clinical Diagnostics (Rochester, NY), using a panel of serially collected serum samples ( = 224) from 56 patients with confirmed coronavirus disease 2019 (COVID-19), healthy donor sera from 2018, and a cross-reactivity serum panel collected in early 2020.

Evaluation of the Bio-Rad BioPlex 2200 IgM Multiplex Flow Immunoassay.

Background: Toxoplasmosis is routinely diagnosed through detection of -specific antibodies. However, the imperfect specificity of serologic assays is a well-recognized limitation. The new BioPlex 2200 (Bio-Rad Laboratories) , rubella, and cytomegalovirus (ToRC) IgM multiplex flow immunoassay (MFI) received FDA clearance in May 2017.

Comparison of the QuantiFERON-TB Gold Plus and QuantiFERON-TB Gold In-Tube Interferon Gamma Release Assays in Patients at Risk for Tuberculosis and in Health Care Workers.

The QuantiFERON-TB Gold Plus (QFT-Plus; Qiagen, Germantown, MD) interferon gamma release assay (IGRA) received FDA clearance in 2017 and will replace the prior version of the assay, the QFT-Gold In-Tube (QFT-GIT). Here, we compared performances of the QFT-Plus assay and the QFT-GIT version in a diverse patient population, including patients undergoing evaluation for or follow-up of latent tuberculosis infection (LTBI; = 39) or active TB infection ( = 3), and in health care workers (HCWs; = 119) at Mayo Clinic (Rochester, MN). Compared to the QFT-GIT, the QFT-Plus assay showed 91.

Serologic Testing for Zika Virus: Comparison of Three Zika Virus IgM-Screening Enzyme-Linked Immunosorbent Assays and Initial Laboratory Experiences.

Serologic evaluation for Zika virus (ZIKV) infection currently includes an initial screen using an anti-ZIKV IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) followed by supplemental testing of specimens with nonnegative results by a plaque reduction neutralization test (PRNT). We compared the performance characteristics of three ELISAs for the detection of IgM class antibodies to ZIKV, including the Centers for Disease Control and Prevention (CDC) Zika MAC-ELISA, the InBios ZIKV MAC-ELISA, and the Euroimmun anti-Zika Virus IgM ELISA. Additionally, we present our initial experiences with ZIKV serologic testing from a national reference laboratory perspective.