Sousuke Kubo1,2, Norihisa Ohtake3,4, Kei Miyakawa1, Sundararaj Stanleyraj Jeremiah1, Yutaro Yamaoka1,5, Kota Murohashi2,6, Eri Hagiwara6, Takahiro Mihara7, Atsushi Goto7, Etsuko Yamazaki8, Takashi Ogura6, Takeshi Kaneko2, Takeharu Yamanaka7,9, Akihide Ryo1. 1. Department of Microbiology, Yokohama City University Graduate School of Medicine, Yokohama, Japan. 2. Department of Pulmonology, Yokohama City University Graduate School of Medicine, Yokohama, Japan. 3. Bioscience Division, Reagent Development Department, Tosoh Corporation, Kanagawa, Japan. 4. Advanced Medical Research Center, Yokohama City University, Yokohama, Japan. 5. Life Science Laboratory, Technology and Development Division, Kanto Chemical Co., Inc., Kanagawa, Japan. 6. Department of Respiratory Medicine, Kanagawa Cardiovascular and Respiratory Center, Yokohama, Japan. 7. Department of Health Data Science, Yokohama City University Graduate School of Data Science, Yokohama, Japan. 8. Clinical Laboratory Department, Yokohama City University Hospital, Yokohama, Japan. 9. Department of Biostatistics, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
Abstract
OBJECTIVES: Serological tests for COVID-19 have been instrumental in studying the epidemiology of the disease. However, the performance of the currently available tests is plagued by the problem of variability. We have developed a high-throughput serological test capable of simultaneously detecting total immunoglobulins (Ig) and immunoglobulin G (IgG) against nucleocapsid protein (NP) and spike protein (SP) and report its performance in detecting COVID-19 in clinical samples. METHODS: We designed and prepared reagents for measuring NP-IgG, NP-Total Ig, SP-IgG, and SP-Total Ig (using N-terminally truncated NP (ΔN-NP) or receptor-binding domain (RBD) antigen) dedicated automated chemiluminescent enzyme immunoassay analyzer AIA-CL1200. After determining the basal thresholds based on 17 sera obtained from confirmed COVID-19 patients and 600 negative sera, the clinical validity of the assay was evaluated using independent 202 positive samples and 1,000 negative samples from healthy donors. RESULTS: All of the four test parameters showed 100% specificity individually (1,000/1,000; 95%CI, 99.63-100). The sensitivity of the assay increased proportionally to the elapsed time from symptoms onset, and all the tests achieved 100% sensitivity (153/153; 95%CI, 97.63-100) after 13 days from symptoms onset. NP-Total Ig was the earliest to attain maximal sensitivity among the other antibodies tested. CONCLUSION: Our newly developed serological testing exhibited 100% sensitivity and specificity after 13 days from symptoms onset. Hence, it could be used as a reliable method for accurate detection of COVID-19 patients and to evaluate seroprevalence and possibly for surrogate assessment of herd immunity.
OBJECTIVES: Serological tests for COVID-19 have been instrumental in studying the epidemiology of the disease. However, the performance of the currently available tests is plagued by the problem of variability. We have developed a high-throughput serological test capable of simultaneously detecting total immunoglobulins (Ig) and immunoglobulin G (IgG) against nucleocapsid protein (NP) and spike protein (SP) and report its performance in detecting COVID-19 in clinical samples. METHODS: We designed and prepared reagents for measuring NP-IgG, NP-Total Ig, SP-IgG, and SP-Total Ig (using N-terminally truncated NP (ΔN-NP) or receptor-binding domain (RBD) antigen) dedicated automated chemiluminescent enzyme immunoassay analyzer AIA-CL1200. After determining the basal thresholds based on 17 sera obtained from confirmed COVID-19 patients and 600 negative sera, the clinical validity of the assay was evaluated using independent 202 positive samples and 1,000 negative samples from healthy donors. RESULTS: All of the four test parameters showed 100% specificity individually (1,000/1,000; 95%CI, 99.63-100). The sensitivity of the assay increased proportionally to the elapsed time from symptoms onset, and all the tests achieved 100% sensitivity (153/153; 95%CI, 97.63-100) after 13 days from symptoms onset. NP-Total Ig was the earliest to attain maximal sensitivity among the other antibodies tested. CONCLUSION: Our newly developed serological testing exhibited 100% sensitivity and specificity after 13 days from symptoms onset. Hence, it could be used as a reliable method for accurate detection of COVID-19 patients and to evaluate seroprevalence and possibly for surrogate assessment of herd immunity.
Authors: Andrew Bryan; Gregory Pepper; Mark H Wener; Susan L Fink; Chihiro Morishima; Anu Chaudhary; Keith R Jerome; Patrick C Mathias; Alexander L Greninger Journal: J Clin Microbiol Date: 2020-07-23 Impact factor: 5.948
Authors: Chek Meng Poh; Guillaume Carissimo; Bei Wang; Siti Naqiah Amrun; Cheryl Yi-Pin Lee; Rhonda Sin-Ling Chee; Siew-Wai Fong; Nicholas Kim-Wah Yeo; Wen-Hsin Lee; Anthony Torres-Ruesta; Yee-Sin Leo; Mark I-Cheng Chen; Seow-Yen Tan; Louis Yi Ann Chai; Shirin Kalimuddin; Shirley Seah Gek Kheng; Siew-Yee Thien; Barnaby Edward Young; David C Lye; Brendon John Hanson; Cheng-I Wang; Laurent Renia; Lisa F P Ng Journal: Nat Commun Date: 2020-06-01 Impact factor: 14.919