Abstract
There is evidence that COVID-19 convalescent plasma may improve outcomes of patients with impaired immune systems; however, more clinical trials are required. Although we have previously used a 50% plaque reduction/neutralization titer (PRNT 50 ) assay to qualify convalescent plasma for clinical trials and virus-like particle (VLP) assays to validate PRNT 50 methodologies, these approaches are time-consuming and expensive. Here, we characterized the ability of the Abbott severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG II Quant assay to identify high- and low-titer plasma for wild-type and variant (Alpha, Beta, Gamma, and Delta) SARS-CoV-2 characterized by both VLP assays and PRNT 50 . Plasma specimens previously tested in wild-type, Alpha, Beta, Gamma, and Delta VLP neutralization assays were selected based on availability. Selected specimens were evaluated by the Abbott SARS-CoV-2 IgG II Quant assay [Abbott anti-Spike (S); Abbott, Chicago, IL], and values in units per milliliter were converted to binding antibody units (BAU) per milliliter. Sixty-three specimens were available for analysis. Abbott SARS-CoV-2 IgG II Quant assay values in BAU per milliliter were significantly different between high- and low-titer specimens for wild-type (Mann-Whitney U = 42, P < 0.0001), Alpha (Mann-Whitney U = 38, P < 0.0001), Beta (Mann-Whitney U = 29, P < 0.0001), Gamma (Mann-Whitney U = 0, P < 0.0001), and Delta (Mann-Whitney U = 42, P < 0.0001). A conservative approach using the highest 95% confidence interval (CI) values from wild-type and variant of concern (VOC) SARS-CoV-2 experiments would identify a potential Abbott SARS-CoV-2 IgG II Quant assay cutoff of ≥7.1 × 10 3 BAU/mL. IMPORTANCE The United States Food and Drug Administration (FDA) issued an Emergency Use Authorization (EUA) for the use of COVID-19 convalescent plasma (CCP) to treat hospitalized patients with COVID-19 in August 2020. However, by 4 February 2021, the FDA had revised the convalescent plasma EUA. This revision limited the authorization for high-titer COVID-19 convalescent plasma and restricted patient groups to hospitalized patients with COVID-19 early in their disease course or hospitalized patients with impaired humoral immunity. Traditionally our group utilized 50% plaque reduction/neutralization titer (PRNT 50 ) assays to qualify CCP in Canada. Since that time, the Abbott SARS-CoV-2 IgG II Quant assay (Abbott, Chicago IL) was developed for the qualitative and quantitative determination of IgG against the SARS-CoV-2. Here, we characterized the ability of the Abbott SARS-CoV-2 IgG II Quant assay to identify high- and low-titer plasma for wild-type and variant (Alpha, Beta, Gamma, and Delta) SARS-CoV-2.
Keywords: COVID-19 convalescent plasma; SARS-CoV-2 antibody; method comparisons; neutralizing antibody; plaque reduction neutralization.
【저자키워드】 neutralizing antibody, SARS-CoV-2 antibody, COVID-19 convalescent plasma, plaque reduction neutralization., method comparisons, 【초록키워드】 COVID-19, convalescent plasma, SARS-CoV-2, IgG, coronavirus, clinical trial, VoC, variant, Delta, drug, outcome, FDA, immune, EUA, Humoral immunity, Neutralization assay, BAU, Patient, Gamma, plasma, Beta, Neutralizing, experiment, convalescent, Canada, Chicago, VLP, PRNT, food, Evidence, Analysis, Emergency, Abbott, CCP, acute respiratory syndrome, 95% confidence interval, disease course, specimen, Cutoff, treat, wild-type, authorization, quantitative determination, Mann-Whitney U, plaque reduction neutralization, Abbott SARS-CoV-2 IgG, Chicago IL, approach, IMPROVE, selected, highest, tested, identify, approach, significantly, United State, evaluated, required, patient group, characterized, hospitalized patient, time-consuming, binding antibody unit, the SARS-CoV-2, with COVID-19, 【제목키워드】 SARS-CoV-2, utilization, Abbott SARS-CoV-2 IgG,