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Objective: To convert manual ELISA kits to fully automated immunoassays that quantify serum drug levels and anti-drug antibodies levels of infliximab and adalimumab (CHORUS Promonitor kits). Desing and methods: CHORUS Promonitor INFLIXIMAB, CHORUS Promonitor ADALIMUMAB, CHORUS Promonitor ANTI-INFLIXIMAB, and CHORUS Promonitor ANTI-ADALIMUMAB kits were compared with the corresponding Promonitor kits to determine sensitivity and specificity of the assays. For the automated assays, the entire procedure -from samples dilution to final readouts-was performed by CHORUS TRIO instrument (DIESSE, Italy). Residual human serum samples from clinical laboratory investigations and samples resulting from the addition of specific drugs (IFX or ADL) or anti-drug antibodies (anti-IFX or anti-ADL) were used for the characterization and validation of the tests. Results: CHORUS Promonitor kits showed an excellent agreement (Cohen's coefficient = 1) with the Promonitor kits and were linear within predefined ranges. All assays were accurate and repeatable, as an acceptable variability were observed within runs, between runs, lots, and instruments. No difference in detecting the reference drug or biosimilars emerged. Conclusion: During preclinical development, these kits resulted as sensitive, specific, accurate, and able to quantify either the reference drug or the corresponding biosimilars. All these features support their use in clinical practice for therapeutic drug monitoring of patients with inflammatory diseases under treatment with IFX or ADL.
RESUMO
OBJECTIVES: Serological assays for SARS-CoV-2 have a critical role not only in diagnosis of COVID-19, but also in assessing the degree and duration of response of specific antibodies against the virus obtained through infection or vaccination. We present the results obtained with a competitive immunoenzymatic method (Chorus SARS-CoV-2 "Neutralizing" Ab) for quantitative determination of total neutralizing anti-S1 SARS-CoV-2 antibodies (IgG, IgM, and IgA) in human serum obtained on a disposable device with the Chorus TRIO instrument using a recombinant strong neutralizing antibody as tracer. METHODS: A total of 694 sera were evaluated for SARS-CoV-2 neutralizing antibodies: 407 uninfected, 201 symptomatic subjects, 37 post-infection patients, and 49 vaccinated. Sixty-eight of the previous sera were used to compare the Chorus SARS-CoV-2 "Neutralizing" Ab results with those obtained with micro-neutralization of the Alpha and original variants. A set of 74 positive sera for other respiratory infections were analyzed to evaluate the possible cross reaction to SARS-CoV-2 virus. RESULTS: Of the 694 samples, only 3 had discordant results between micro-neutralization and values measured by Chorus SARS-CoV-2 "Neutralizing" Ab: 1 false negative and 2 false positives. Values of sensitivity and specificity were very high: percent positive agreement (sensitivity) 99.6% (95% CI: 97.7 - 99.9) and percent negative agreement (specificity) 99.6% (95% CI: 98.0 -99.9). Concordance was high with a Gwet's Ac1 of 0.992. No significant differences were observed between the alpha and original variants. CONCLUSIONS: The Chorus SARS-CoV-2 "Neutralizing" Ab test was highly sensitive and specific, and varies from most other currently available tests since it analyzes only antibodies with viral-neutralizing capacity.
