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    Ultrasensitive high-resolution profiling of early seroconversion in patients with COVID-19. Norman Maia,Gilboa Tal,Ogata Alana F,Maley Adam M,Cohen Limor,Busch Evan L,Lazarovits Roey,Mao Chih-Ping,Cai Yongfei,Zhang Jun,Feldman Jared E,Hauser Blake M,Caradonna Timothy M,Chen Bing,Schmidt Aaron G,Alter Galit,Charles Richelle C,Ryan Edward T,Walt David R Nature biomedical engineering Sensitive assays are essential for the accurate identification of individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here, we report a multiplexed assay for the fluorescence-based detection of seroconversion in infected individuals from less than 1 µl of blood, and as early as the day of the first positive nucleic acid test after symptom onset. The assay uses dye-encoded antigen-coated beads to quantify the levels of immunoglobulin G (IgG), IgM and IgA antibodies against four SARS-CoV-2 antigens. A logistic regression model trained using samples collected during the pandemic and samples collected from healthy individuals and patients with respiratory infections before the first outbreak of coronavirus disease 2019 (COVID-19) was 99% accurate in the detection of seroconversion in a blinded validation cohort of samples collected before the pandemic and from patients with COVID-19 five or more days after a positive nasopharyngeal test by PCR with reverse transcription. The high-throughput serological profiling of patients with COVID-19 allows for the interrogation of interactions between antibody isotypes and viral proteins, and should help us to understand the heterogeneity of clinical presentations. 10.1038/s41551-020-00611-x
    Evaluation of SARS-CoV-2 serology assays reveals a range of test performance. Whitman Jeffrey D,Hiatt Joseph,Mowery Cody T,Shy Brian R,Yu Ruby,Yamamoto Tori N,Rathore Ujjwal,Goldgof Gregory M,Whitty Caroline,Woo Jonathan M,Gallman Antonia E,Miller Tyler E,Levine Andrew G,Nguyen David N,Bapat Sagar P,Balcerek Joanna,Bylsma Sophia A,Lyons Ana M,Li Stacy,Wong Allison Wai-Yi,Gillis-Buck Eva Mae,Steinhart Zachary B,Lee Youjin,Apathy Ryan,Lipke Mitchell J,Smith Jennifer Anne,Zheng Tina,Boothby Ian C,Isaza Erin,Chan Jackie,Acenas Dante D,Lee Jinwoo,Macrae Trisha A,Kyaw Than S,Wu David,Ng Dianna L,Gu Wei,York Vanessa A,Eskandarian Haig Alexander,Callaway Perri C,Warrier Lakshmi,Moreno Mary E,Levan Justine,Torres Leonel,Farrington Lila A,Loudermilk Rita P,Koshal Kanishka,Zorn Kelsey C,Garcia-Beltran Wilfredo F,Yang Diane,Astudillo Michael G,Bernstein Bradley E,Gelfand Jeffrey A,Ryan Edward T,Charles Richelle C,Iafrate A John,Lennerz Jochen K,Miller Steve,Chiu Charles Y,Stramer Susan L,Wilson Michael R,Manglik Aashish,Ye Chun Jimmie,Krogan Nevan J,Anderson Mark S,Cyster Jason G,Ernst Joel D,Wu Alan H B,Lynch Kara L,Bern Caryn,Hsu Patrick D,Marson Alexander Nature biotechnology Appropriate use and interpretation of serological tests for assessments of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure, infection and potential immunity require accurate data on assay performance. We conducted a head-to-head evaluation of ten point-of-care-style lateral flow assays (LFAs) and two laboratory-based enzyme-linked immunosorbent assays to detect anti-SARS-CoV-2 IgM and IgG antibodies in 5-d time intervals from symptom onset and studied the specificity of each assay in pre-coronavirus disease 2019 specimens. The percent of seropositive individuals increased with time, peaking in the latest time interval tested (>20 d after symptom onset). Test specificity ranged from 84.3% to 100.0% and was predominantly affected by variability in IgM results. LFA specificity could be increased by considering weak bands as negative, but this decreased detection of antibodies (sensitivity) in a subset of SARS-CoV-2 real-time PCR-positive cases. Our results underline the importance of seropositivity threshold determination and reader training for reliable LFA deployment. Although there was no standout serological assay, four tests achieved more than 80% positivity at later time points tested and more than 95% specificity. 10.1038/s41587-020-0659-0
    Rapid lateral flow immunoassay for the fluorescence detection of SARS-CoV-2 RNA. Wang Daming,He Shaogui,Wang Xiaohui,Yan Youqin,Liu Jianzhong,Wu Shimin,Liu Shiguo,Lei Yang,Chen Min,Li Li,Zhang Jieli,Zhang Liwei,Hu Xiao,Zheng Xinhui,Bai Jiawei,Zhang Yulong,Zhang Yitong,Song Mingxuan,Tang Yuguo Nature biomedical engineering The coronavirus disease 2019 (COVID-19) pandemic has highlighted the need for rapid and accurate nucleic acid detection at the point of care. Here, we report an amplification-free nucleic acid immunoassay, implemented on a lateral flow strip, for the fluorescence detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in less than one hour. The assay uses DNA probes that are designed to bind to the conserved open reading frame 1ab (ORF1ab), envelope protein (E) and the nucleocapsid (N) regions of the SARS-CoV-2 genome, and a fluorescent-nanoparticle-labelled monoclonal antibody that binds to double-stranded DNA-RNA hybrids. In a multi-hospital randomized double-blind trial involving 734 samples (593 throat swabs and 141 sputum) provided by 670 individuals, the assay achieved sensitivities of 100% and specificities of 99% for both types of sample (ground truth was determined using quantitative PCR with reverse transcription). The inexpensive amplification-free detection of SARS-CoV-2 RNA should facilitate the rapid diagnosis of COVID-19 at the point of care. 10.1038/s41551-020-00655-z