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Evaluation of a SARS-CoV-2 Capture IgM Antibody Assay in Convalescent Sera.
Microbiol Spectr. 2021 10 31; 9(2):e0045821.MS

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for a global pandemic with over 152 million cases and 3.19 million deaths reported by early May 2021. Understanding the serological response to SARS-CoV-2 is critical to determining the burden of infection and disease (coronavirus disease 2019 [COVID-19]) and transmission dynamics. We developed a capture IgM assay because it should have better sensitivity and specificity than the commonly used indirect assay. Here, we report the development and performance of a capture IgM enzyme-linked immunosorbent assay (ELISA) and a companion indirect IgG ELISA for the spike (S) and nucleocapsid (N) proteins and the receptor-binding domain (RBD) of S. We found that among the IgM ELISAs, the S ELISA was positive in 76% of 55 serum samples from SARS-CoV-2 PCR-positive patients, the RBD ELISA was positive in 55% of samples, and the N ELISA was positive in 15% of samples. The companion indirect IgG ELISAs were positive for S in 89% of the 55 serum samples, RBD in 78%, and N in 85%. While the specificities for IgM RBD, S, and N ELISAs and IgG S and RBD ELISAs were 97% to 100%, the specificity of the N IgG ELISA was lower (89%). RBD-specific IgM antibodies became undetectable by 3 to 6 months, and S IgM reached low levels at 6 months. The corresponding IgG S, RBD, and N antibodies persisted with some decreases in levels over this time period. These capture IgM ELISAs and the companion indirect IgG ELISAs should enhance serologic studies of SARS-CoV-2 infections. IMPORTANCE Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has inflicted tremendous loss of lives, overwhelmed health care systems, and disrupted all aspects of life worldwide since its emergence in Wuhan, China, in December 2019. Detecting current and past infection by PCR or serology is important to understanding and controlling SARS-CoV-2. With increasing prevalence of past infection or vaccination, IgG antibodies are less helpful in diagnosing a current infection. IgM antibodies indicate a more recent infection and can supplement PCR diagnosis. We report an alternative method, capture IgM, to detect serum IgM antibodies, which should be more sensitive and specific than most currently used methods. We describe this capture IgM assay and a companion indirect IgG assay for the SARS-CoV-2 spike (S), nucleocapsid (N), and receptor-binding domain (RBD) proteins. These assays can add value to diagnostic and serologic studies of coronavirus disease 2019 (COVID-19).

Authors+Show Affiliations

Division of Pediatric Infectious Diseases, Emory University School of Medicinegrid.471395.d and Children's Health Care of Atlanta, Atlanta, Georgia, USA.Division of Pediatric Infectious Diseases, Emory University School of Medicinegrid.471395.d and Children's Health Care of Atlanta, Atlanta, Georgia, USA.Division of Pediatric Infectious Diseases, Emory University School of Medicinegrid.471395.d and Children's Health Care of Atlanta, Atlanta, Georgia, USA.Division of Pediatric Infectious Diseases, Emory University School of Medicinegrid.471395.d and Children's Health Care of Atlanta, Atlanta, Georgia, USA.Division of Pediatric Infectious Diseases, Emory University School of Medicinegrid.471395.d and Children's Health Care of Atlanta, Atlanta, Georgia, USA.Division of Pediatric Infectious Diseases, Emory University School of Medicinegrid.471395.d and Children's Health Care of Atlanta, Atlanta, Georgia, USA.Division of Pediatric Infectious Diseases, Emory University School of Medicinegrid.471395.d and Children's Health Care of Atlanta, Atlanta, Georgia, USA.Division of Pediatric Infectious Diseases, Emory University School of Medicinegrid.471395.d and Children's Health Care of Atlanta, Atlanta, Georgia, USA.Division of Infectious Diseases, Department of Medicine, Emory University School of Medicinegrid.471395.d, Atlanta, Georgia, USA.Division of Infectious Diseases, Department of Medicine, Emory University School of Medicinegrid.471395.d, Atlanta, Georgia, USA.Division of Pediatric Infectious Diseases, Emory University School of Medicinegrid.471395.d and Children's Health Care of Atlanta, Atlanta, Georgia, USA.Department of Infectious Diseases, University of Georgiagrid.213876.9, Athens, Georgia, USA. Center for Vaccines and Immunology, University of Georgiagrid.213876.9, Athens, Georgia, USA. Emory-UGA Centers of Excellence for Influenza Research and Surveillance (CEIRS), Athens, Georgia, USA.Division of Pediatric Infectious Diseases, Emory University School of Medicinegrid.471395.d and Children's Health Care of Atlanta, Atlanta, Georgia, USA. Division of Infectious Diseases, Department of Medicine, Emory University School of Medicinegrid.471395.d, Atlanta, Georgia, USA.Division of Pediatric Infectious Diseases, Emory University School of Medicinegrid.471395.d and Children's Health Care of Atlanta, Atlanta, Georgia, USA.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

34494855

Citation

Ha, Binh, et al. "Evaluation of a SARS-CoV-2 Capture IgM Antibody Assay in Convalescent Sera." Microbiology Spectrum, vol. 9, no. 2, 2021, pp. e0045821.
Ha B, Jadhao S, Hussaini L, et al. Evaluation of a SARS-CoV-2 Capture IgM Antibody Assay in Convalescent Sera. Microbiol Spectr. 2021;9(2):e0045821.
Ha, B., Jadhao, S., Hussaini, L., Gibson, T., Stephens, K., Salazar, L., Ciric, C., Taylor, M., Rouphael, N., Edupuganti, S., Rostad, C. A., Tompkins, S. M., Anderson, E. J., & Anderson, L. J. (2021). Evaluation of a SARS-CoV-2 Capture IgM Antibody Assay in Convalescent Sera. Microbiology Spectrum, 9(2), e0045821. https://doi.org/10.1128/Spectrum.00458-21
Ha B, et al. Evaluation of a SARS-CoV-2 Capture IgM Antibody Assay in Convalescent Sera. Microbiol Spectr. 2021 10 31;9(2):e0045821. PubMed PMID: 34494855.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Evaluation of a SARS-CoV-2 Capture IgM Antibody Assay in Convalescent Sera. AU - Ha,Binh, AU - Jadhao,Samadhan, AU - Hussaini,Laila, AU - Gibson,Theda, AU - Stephens,Kathy, AU - Salazar,Luis, AU - Ciric,Caroline, AU - Taylor,Meg, AU - Rouphael,Nadine, AU - Edupuganti,Srilatha, AU - Rostad,Christina A, AU - Tompkins,S Mark, AU - Anderson,Evan J, AU - Anderson,Larry J, Y1 - 2021/09/08/ PY - 2021/9/9/pubmed PY - 2021/11/16/medline PY - 2021/9/8/entrez KW - COVID-19 KW - IgG ELISA KW - SARS-CoV-2 KW - antibody duration KW - capture IgM ELISA SP - e0045821 EP - e0045821 JF - Microbiology spectrum JO - Microbiol Spectr VL - 9 IS - 2 N2 - Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for a global pandemic with over 152 million cases and 3.19 million deaths reported by early May 2021. Understanding the serological response to SARS-CoV-2 is critical to determining the burden of infection and disease (coronavirus disease 2019 [COVID-19]) and transmission dynamics. We developed a capture IgM assay because it should have better sensitivity and specificity than the commonly used indirect assay. Here, we report the development and performance of a capture IgM enzyme-linked immunosorbent assay (ELISA) and a companion indirect IgG ELISA for the spike (S) and nucleocapsid (N) proteins and the receptor-binding domain (RBD) of S. We found that among the IgM ELISAs, the S ELISA was positive in 76% of 55 serum samples from SARS-CoV-2 PCR-positive patients, the RBD ELISA was positive in 55% of samples, and the N ELISA was positive in 15% of samples. The companion indirect IgG ELISAs were positive for S in 89% of the 55 serum samples, RBD in 78%, and N in 85%. While the specificities for IgM RBD, S, and N ELISAs and IgG S and RBD ELISAs were 97% to 100%, the specificity of the N IgG ELISA was lower (89%). RBD-specific IgM antibodies became undetectable by 3 to 6 months, and S IgM reached low levels at 6 months. The corresponding IgG S, RBD, and N antibodies persisted with some decreases in levels over this time period. These capture IgM ELISAs and the companion indirect IgG ELISAs should enhance serologic studies of SARS-CoV-2 infections. IMPORTANCE Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has inflicted tremendous loss of lives, overwhelmed health care systems, and disrupted all aspects of life worldwide since its emergence in Wuhan, China, in December 2019. Detecting current and past infection by PCR or serology is important to understanding and controlling SARS-CoV-2. With increasing prevalence of past infection or vaccination, IgG antibodies are less helpful in diagnosing a current infection. IgM antibodies indicate a more recent infection and can supplement PCR diagnosis. We report an alternative method, capture IgM, to detect serum IgM antibodies, which should be more sensitive and specific than most currently used methods. We describe this capture IgM assay and a companion indirect IgG assay for the SARS-CoV-2 spike (S), nucleocapsid (N), and receptor-binding domain (RBD) proteins. These assays can add value to diagnostic and serologic studies of coronavirus disease 2019 (COVID-19). SN - 2165-0497 UR - https://www.unboundmedicine.com/medline/citation/34494855/Evaluation_of_a_SARS_CoV_2_Capture_IgM_Antibody_Assay_in_Convalescent_Sera_ L2 - https://doi.org/10.1128/Spectrum.00458-21 DB - PRIME DP - Unbound Medicine ER -