Brigger, DanielDanielBriggerHorn, MichaelMichaelHorn0000-0002-5772-6342Pennington, L. F.L. F.PenningtonPowell, A. E.A. E.PowellSiegrist, D.D.SiegristWeber, B.B.WeberEngler, O.O.EnglerPiezzi, VanjaVanjaPiezziDamonti, LauroLauroDamontiIseli, P.P.IseliHauser, Christoph VictorChristoph VictorHauser0000-0002-2413-8931Fröhlich, TanjaTanjaFröhlichVilliger, PeterPeterVilligerBachmann, MartinMartinBachmannLeib, StephenStephenLeib0000-0002-1106-6123Bittel, PascalPascalBittelFiedler, Georg MartinGeorg MartinFiedlerLargiadèr, Carlo RodolfoCarlo RodolfoLargiadèrMarschall, JonasJonasMarschall0000-0002-0052-3210Stalder, HanspeterHanspeterStalderKim, P. S.P. S.KimJardetzky, T. S.T. S.JardetzkyEggel, AlexanderAlexanderEggel0000-0001-8746-3339Nagler, MichaelMichaelNagler2024-09-202024-09-202021-03https://boris-portal.unibe.ch/handle/20.500.12422/45052BACKGROUND Serological immunoassays that can identify protective immunity against SARS-CoV-2 are needed to adapt quarantine measures, assess vaccination responses, and evaluate donor plasma. To date, however, the utility of such immunoassays remains unclear. In a mixed-design evaluation study, we compared the diagnostic accuracy of serological immunoassays that are based on various SARS-CoV-2 proteins and assessed the neutralizing activity of antibodies in patient sera. METHODS Consecutive patients admitted with confirmed SARS-CoV-2 infection were prospectively followed alongside medical staff and biobank samples from winter 2018/2019. An in-house enzyme-linked immunosorbent assay utilizing recombinant receptor-binding domain (RBD) of the SARS-CoV-2 spike protein was developed and compared to three commercially available enzyme-linked immunosorbent assays (ELISAs) targeting the nucleoprotein (N), the S1 domain of the spike protein (S1) and a lateral flow immunoassay (LFI) based on full-length spike protein. Neutralization assays with live SARS-CoV-2 were performed. RESULTS One-thousand four-hundred and seventy-seven individuals were included comprising 112 SARS-CoV-2 positives (defined as a positive real-time PCR result; prevalence 7.6%). IgG seroconversion occurred between day 0 and day 21. While the ELISAs showed sensitivities of 88.4% for RBD, 89.3% for S1, and 72.9% for N protein, the specificity was above 94% for all tests. Out of 54 SARS-CoV-2 positive individuals, 96.3% showed full neutralization of live SARS-CoV-2 at serum dilutions ≥1:16, while none of the 6 SARS-CoV-2 negative sera revealed neutralizing activity. CONCLUSIONS ELISAs targeting RBD and S1 protein of SARS-CoV-2 are promising immunoassays which shall be further evaluated in studies verifying diagnostic accuracy and protective immunity against SARS-CoV-2.enAntibodies COVID-19 COVID-19 diagnostic testing Enzyme-Linked Immunosorbent Assay Neutralizing Severe Acute Respiratory Syndrome Coronavirus 2600 - Technology::610 - Medicine & health600 - Technology::630 - Agriculture500 - Science::570 - Life sciences; biologyarticle10.7892/boris.1470523299781210.1111/all.14608