{"doi":"10.1101/2020.11.09.20228411","title":"Quantitative measurement of IgG to SARS-CoV-2 proteins using ImmunoCAP","abstract":"BACKGROUND: Detailed understanding of the immune response to SARS-CoV-2, the cause of coronavirus disease 2019 (COVID-19), has been hampered by a lack of quantitative antibody assays. OBJECTIVE: To develop a quantitative assay for IgG to SARS-CoV-2 proteins that could readily be implemented in clinical and research laboratories. METHODS: The biotin-streptavidin technique was used to conjugate SARS-CoV-2 spike receptor-binding-domain (RBD) or nucleocapsid protein to the solid-phase of the ImmunoCAP resin. Plasma and serum samples from patients with COVID-19 (n=51) and samples from donors banked prior to the emergence of COVID-19 (n=109) were used in the assay. SARS-CoV-2 IgG levels were followed longitudinally in a subset of samples and were related to total IgG and IgG to reference antigens using an ImmunoCAP 250 platform. RESULTS: Performance characteristics demonstrated 100% sensitivity and 99% specificity at a cut-off level of 2.5 µg/mL for both SARS-CoV-2 proteins. Among 36 patients evaluated in a post-hospital follow-up clinic, median levels of IgG to spike-RBD and nucleocapsid were 34.7 µg/mL (IQR 18-52) and 24.5 µg/mL (IQR 9-59), respectively. Among 17 patients with longitudinal samples there was a wide variation in the magnitude of IgG responses, but generally the response to spike-RBD and to nucleocapsid occurred in parallel, with peak levels approaching 100 µg/mL, or 1% of total IgG. CONCLUSIONS: We have described a quantitative assay to measure IgG to SARS-CoV-2 that could be used in clinical and research laboratories and implemented at scale. The assay can easily be adapted to measure IgG to novel antigens, has good performance characteristics and a read-out in standardized units.","journal":"Florentia iliberritana: Revista de estudios de antigüedad clásica","year":2020,"id":127621,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":1,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9569,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2020-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":576993,"name":"Joesph R Wiencek","orcid":"0000-0001-9595-6299","position":1,"is_corresponding":false},{"id":352052,"name":"Lisa J. Workman","orcid":null,"position":2,"is_corresponding":false},{"id":333115,"name":"Matthew Straesser","orcid":null,"position":3,"is_corresponding":false},{"id":350268,"name":"Lyndsey M. Muehling","orcid":"0000-0003-3203-3264","position":4,"is_corresponding":false},{"id":576994,"name":"Glenda Canderan","orcid":"0000-0001-8388-9930","position":5,"is_corresponding":false},{"id":475502,"name":"Fabrizio Drago","orcid":"0000-0002-8591-7103","position":6,"is_corresponding":false},{"id":339142,"name":"Catherine A. Bonham","orcid":"0000-0001-9132-4083","position":7,"is_corresponding":false},{"id":59341,"name":"Jeffrey M. Sturek","orcid":"0000-0002-2731-3299","position":8,"is_corresponding":false},{"id":577905,"name":"Chintan Ramani","orcid":null,"position":9,"is_corresponding":false},{"id":363873,"name":"Coleen A. McNamara","orcid":"0000-0002-0049-9986","position":10,"is_corresponding":false},{"id":350271,"name":"Judith A. Woodfolk","orcid":"0000-0002-8915-4334","position":11,"is_corresponding":false},{"id":328780,"name":"Alexandra Kadl","orcid":"0000-0001-6285-574X","position":12,"is_corresponding":false},{"id":334951,"name":"Thomas A.E. Platts‐Mills","orcid":"0000-0002-1263-329X","position":13,"is_corresponding":false},{"id":334949,"name":"Jeffrey M. Wilson","orcid":"0000-0002-5975-1760","position":14,"is_corresponding":false},{"id":408228,"name":"Behnam Keshavarz","orcid":null,"position":0,"is_corresponding":true}],"reference_count":24,"raw_metadata":null,"created_at":"2026-07-18T23:15:34.966380Z","pmid":"33200147","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}