{"doi":"10.1101/2020.08.14.20175356","title":"SARS-Coronavirus-2 nucleocapsid protein measured in blood using a Simoa ultra-sensitive immunoassay differentiates COVID-19 infection with high clinical sensitivity","abstract":"Abstract The COVID-19 pandemic continues to have an unprecedented impact on societies and economies worldwide. Despite rapid advances in diagnostic test development and scale-up, there remains an ongoing need for SARS-CoV-2 tests which are highly sensitive, specific, minimally invasive, cost-effective and scalable for broad testing and surveillance. Here we report development of a highly sensitive single molecule array (Simoa) immunoassay on the automated HD-X platform for the detection of SARS-CoV-2 Nucleocapsid protein (N-protein) in venous and capillary blood (fingerstick). In pre-pandemic and clinical sample sets, the assay has 100% specificity and 97.4% sensitivity for serum / plasma samples. The limit of detection (LoD) estimated by titration of inactivated SARS-CoV-2 virus is 0.2 pg/ml, corresponding to 0.05 Median Tissue Culture Infectious Dose (TCID50) per ml, > 2000 times more sensitive than current EUA approved antigen tests. No cross-reactivity to other common respiratory viruses, including hCoV229E, hCoVOC43, hCoVNL63, Influenza A or Influenza B, was observed. We detected elevated N-protein concentrations in symptomatic, asymptomatic, and pre-symptomatic PCR+ individuals using capillary blood from a finger-stick collection device. The Simoa SARS-CoV-2 N-protein assay has the potential to detect COVID-19 infection via antigen in blood with performance characteristics similar to or better than molecular tests, while also enabling at home and point of care sample collection. One Sentence Summary SARS-CoV-2 nucleocapsid protein (N-protein) measured in serum, plasma, and dried blood spots (DBS) via ultrasensitive immunoassay can be used to differentiate PCR+ from PCR- patients, even if asymptomatic.","journal":"medRxiv","year":2020,"id":122249,"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":5,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9626,"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":563122,"name":"Joseph M. Johnson","orcid":"0000-0002-5943-8344","position":1,"is_corresponding":false},{"id":563123,"name":"Syrena C. Fernandes","orcid":"0000-0003-3180-6982","position":2,"is_corresponding":false},{"id":563951,"name":"Muriel Mendes","orcid":null,"position":3,"is_corresponding":false},{"id":563952,"name":"Hannah Suib","orcid":null,"position":4,"is_corresponding":false},{"id":563953,"name":"Marcella Holdridge","orcid":null,"position":5,"is_corresponding":false},{"id":563954,"name":"Elaine M. Burke","orcid":null,"position":6,"is_corresponding":false},{"id":563955,"name":"Katie Beauregard","orcid":null,"position":7,"is_corresponding":false},{"id":563124,"name":"Ying Zhang","orcid":"0000-0001-5103-6538","position":8,"is_corresponding":false},{"id":563956,"name":"Megan Cleary","orcid":null,"position":9,"is_corresponding":false},{"id":283557,"name":"Samantha Xu","orcid":null,"position":10,"is_corresponding":false},{"id":563125,"name":"Yao Xiao","orcid":"0000-0002-2826-1347","position":11,"is_corresponding":false},{"id":563957,"name":"Purvish P. Patel","orcid":null,"position":12,"is_corresponding":false},{"id":563958,"name":"Tatiana Plavina","orcid":null,"position":13,"is_corresponding":false},{"id":563126,"name":"David Wilson","orcid":"0000-0002-5198-7509","position":14,"is_corresponding":false},{"id":28302,"name":"Lei Chang","orcid":"0000-0002-9824-4016","position":15,"is_corresponding":false},{"id":563127,"name":"Kim M Kaiser","orcid":"0000-0002-6755-2104","position":16,"is_corresponding":false},{"id":563959,"name":"Jacob Natterman","orcid":null,"position":17,"is_corresponding":false},{"id":563128,"name":"Susanne V. Schmidt","orcid":"0000-0001-9561-2752","position":18,"is_corresponding":false},{"id":104390,"name":"Eicke Latz","orcid":"0000-0003-1488-5666","position":19,"is_corresponding":false},{"id":563960,"name":"Kevin Hrusovsky","orcid":null,"position":20,"is_corresponding":false},{"id":563129,"name":"Dawn Mattoon","orcid":"0009-0001-4198-5614","position":21,"is_corresponding":false},{"id":563130,"name":"Andrew J. Ball","orcid":"0000-0002-5320-9364","position":22,"is_corresponding":false},{"id":563121,"name":"Dandan Shan","orcid":"0000-0003-4761-7385","position":0,"is_corresponding":true}],"reference_count":23,"raw_metadata":null,"created_at":"2026-07-18T23:14:51.076430Z","pmid":null,"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":[]}