AUTHOR=Halliday Alice , Long Anna E. , Baum Holly E. , Thomas Amy C. , Shelley Kathryn L. , Oliver Elizabeth , Gupta Kapil , Francis Ore , Williamson Maia Kavanagh , Di Bartolo Natalie , Randell Matthew J. , Ben-Khoud Yassin , Kelland Ilana , Mortimer Georgina , Ball Olivia , Plumptre Charlie , Chandler Kyla , Obst Ulrike , Secchi Massimiliano , Piemonti Lorenzo , Lampasona Vito , Smith Joyce , Gregorova Michaela , Knezevic Lea , Metz Jane , Barr Rachael , Morales-Aza Begonia , Oliver Jennifer , Collingwood Lucy , Hitchings Benjamin , Ring Susan , Wooldridge Linda , Rivino Laura , Timpson Nicholas , McKernon Jorgen , Muir Peter , Hamilton Fergus , Arnold David , Woolfson Derek N. , Goenka Anu , Davidson Andrew D. , Toye Ashley M. , Berger Imre , Bailey Mick , Gillespie Kathleen M. , Williams Alistair J. K. , Finn Adam TITLE=Development and evaluation of low-volume tests to detect and characterize antibodies to SARS-CoV-2 JOURNAL=Frontiers in Immunology VOLUME=13 YEAR=2022 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2022.968317 DOI=10.3389/fimmu.2022.968317 ISSN=1664-3224 ABSTRACT=

Low-volume antibody assays can be used to track SARS-CoV-2 infection rates in settings where active testing for virus is limited and remote sampling is optimal. We developed 12 ELISAs detecting total or antibody isotypes to SARS-CoV-2 nucleocapsid, spike protein or its receptor binding domain (RBD), 3 anti-RBD isotype specific luciferase immunoprecipitation system (LIPS) assays and a novel Spike-RBD bridging LIPS total-antibody assay. We utilized pre-pandemic (n=984) and confirmed/suspected recent COVID-19 sera taken pre-vaccination rollout in 2020 (n=269). Assays measuring total antibody discriminated best between pre-pandemic and COVID-19 sera and were selected for diagnostic evaluation. In the blind evaluation, two of these assays (Spike Pan ELISA and Spike-RBD Bridging LIPS assay) demonstrated >97% specificity and >92% sensitivity for samples from COVID-19 patients taken >21 days post symptom onset or PCR test. These assays offered better sensitivity for the detection of COVID-19 cases than a commercial assay which requires 100-fold larger serum volumes. This study demonstrates that low-volume in-house antibody assays can provide good diagnostic performance, and highlights the importance of using well-characterized samples and controls for all stages of assay development and evaluation. These cost-effective assays may be particularly useful for seroprevalence studies in low and middle-income countries.