An original multiplex method to assess five different SARS-CoV-2 antibodies.

Area of Science:

• Immunology
• Virology
• Medical Diagnostics

Background:

• Accurate SARS-CoV-2 serological assays are crucial for diagnosing infections, tracking population exposure, and evaluating vaccine efficacy.
• The D-tek COVIDOT 5 IgG assay was developed to detect multiple SARS-CoV-2 IgG antibodies, including those targeting Nucleocapsid (N), Spike (S1+S2, S1, S2), and Receptor Binding Domain (RBD).

Purpose of the Study:

• To evaluate the performance of the multiplex D-tek COVIDOT 5 IgG assay for detecting SARS-CoV-2 IgG antibodies.
• To assess the sensitivity, dynamic trend of seropositivity, and specificity of the assay.

Main Methods:

• Sensitivity and dynamic trends were assessed using 218 samples from 46 confirmed COVID-19 patients.
• Specificity was determined using 118 pre-pandemic sera, with analysis for potential cross-reactivity.
• The assay targets IgG antibodies against SARS-CoV-2 N, S1+S2, S1, S2, and RBD antigens.

Main Results:

• All targeted IgG antibodies showed a gradual dynamic trend post-symptom onset.
• Sensitivity reached 100% for N, S1+S2, S2, and RBD IgG at ≥21 days post-symptom onset.
• Specificities were excellent, with 100% for S1+S2, S2, and RBD IgG, and 98.3% for N IgG.

Conclusions:

• The D-tek COVIDOT 5 IgG assay demonstrates excellent sensitivity and specificity at ≥21 days post-symptom onset, particularly for N, S1+S2, S2, and RBD antibodies.
• The combined use of multiple antigens enhances early sensitivity while maintaining high specificity.
• This multiplex assay aligns with the CDC's orthogonal testing algorithm, facilitating a more accurate interpretation of patient serological status.