Abstract
Accurate SARS-CoV-2 serological assays are critical for COVID-19 serosurveillance. However, previous studies have indicated possible cross-reactivity of these assays, including in areas where malaria is endemic. We tested 213 well-characterized prepandemic samples from Nigeria using two SARS-CoV-2 serological assays, Abbott Architect IgG and Euroimmun NCP IgG assay, both targeting SARS-CoV-2 nucleocapsid protein. To assess antibody binding strength, an avidity assay was performed on these samples and on plasma from SARS-CoV-2 PCR-positive persons. Thirteen (6.1%) of 212 samples run on the Abbott assay and 38 (17.8%) of 213 run on the Euroimmun assay were positive. Anti- Plasmodium IgG levels were significantly higher among false positives for both Abbott and Euroimmun; no association was found with active Plasmodium falciparum infection. An avidity assay using various concentrations of urea wash in the Euroimmun assay reduced loosely bound IgG: of 37 positive/borderline prepandemic samples, 46%, 86%, 89%, and 97% became negative using 2 M, 4 M, 5 M, and 8 M urea washes, respectively. The wash slightly reduced avidity of antibodies from SARS-CoV-2 patients within 28 days of PCR confirmation; thereafter, avidity increased for all urea concentrations except 8 M. This validation found moderate to substantial cross-reactivity on two SARS-CoV-2 serological assays using samples from a setting where malaria is endemic. A simple urea wash appeared to alleviate issues of cross-reactivity.
Keywords: SARS-CoV-2; cross-reactivity; malaria; serology.
【저자키워드】 SARS-CoV-2, serology, malaria, cross-reactivity, 【초록키워드】 COVID-19, IgG, serology, antibody, Nigeria, malaria, cross-reactivity, Protein, Antibody binding, PCR, Serological assay, serological assays, plasma, avidity, False positive, Euroimmun, Critical, moderate, association, SARS-CoV-2 patients, Endemic, Concentration, False positives, Plasmodium falciparum, Abbott, urea, urea concentrations, Previous studies, PCR-positive, Architect, previous study, Plasmodium, positive, SARS-CoV-2 nucleocapsid, Plasmodium falciparum infection, WASH, tested, indicated, assays, was performed, reduced, significantly higher, alleviate, IgG level, SARS-CoV-2 patient, urea concentration, 【제목키워드】 setting,