Available online 22 January 2023, 115903

Management of the COVID-19 pandemic relies on molecular diagnostic methods supported by serological tools. Herein, we developed S-RBD- and N- based ELISA assays useful for infection rate surveillance as well as the follow-up of acquired protective immunity against SARS-CoV-2. ELISA assays were optimized using COVID-19 Tunisian patients’ sera and pre-pandemic controls. Assays were further validated in three African countries with variable endemic settings. The receiver operating curve was used to evaluate the assays performances. The N- and S-RBD-based ELISA assays performances, in Tunisia, were very high (AUC: 0.966 and 0.98, respectively, p< 0.0001). Cross-validation analysis showed similar performances in different settings. Cross-reactivity, with malaria infection, against viral antigens was noticed. In head-to-head comparisons with different commercial assays, the developed assays showed high agreement. This study demonstrates, the added value of the developed serological assays in low-income countries, particularly in ethnically diverse populations with variable exposure to local endemic infectious diseases.

ELISA

Nucleoprotein N

S-RBD

COVID-19

Multicentric validation

Endemic African settings

Coronavirus disease 2019

Enzyme-Linked Immunosorbent Assay

Horseradish peroxidase

isopropyl-β-D-thiogalactopyranoside

Luciferase immunoprecipitation system

Matrix assisted laser desorption ionization-time of flight

Middle east respiratory syndrome coronavirus

Phosphate buffered saline

Receiver operating curve

Reverse transcription polymerase chain reaction

Severe acute respiratory syndrome coronavirus

Receptor-binding domain of the spike protein

3,3′,5,5′-tetramethylbenzidine

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