Diagnostic value and characteristic analysis of serum nucleocapsid antigen in COVID-19 patients

Xihong Zhang; Chungen Qian; Li Yang; Huixia Gao; Ping Jiang; Muwei Dai; Yuling Wang; Haiyan Kang; Yi Xu; Qian Hu; Fumin Feng; Bangning Cheng; Erhei Dai

doi:10.7717/peerj.15515

PeerJ (Jun 2023)

Diagnostic value and characteristic analysis of serum nucleocapsid antigen in COVID-19 patients

Xihong Zhang,
Chungen Qian,
Li Yang,
Huixia Gao,
Ping Jiang,
Muwei Dai,
Yuling Wang,
Haiyan Kang,
Yi Xu,
Qian Hu,
Fumin Feng,
Bangning Cheng,
Erhei Dai

Affiliations

Xihong Zhang: School of Public Health, North China University of Science and Technology, Tangshan, Hebei, China
Chungen Qian: The Key Laboratory for Biomedical Photonics of MOE at Wuhan National Laboratory for Optoelectronics-Hubei Bioinformatics & Molecular Imaging Key Laboratory, Systems Biology Theme, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
Li Yang: Department of Laboratory Medicine, The Fifth Hospital of Shijiazhuang, North China University of Science and Technology, Shijiazhuang, Hebei, China
Huixia Gao: Department of Laboratory Medicine, The Fifth Hospital of Shijiazhuang, North China University of Science and Technology, Shijiazhuang, Hebei, China
Ping Jiang: Department of Tuberculosis, The Fifth Hospital of Shijiazhuang, North China University of Science and Technology, Shijiazhuang, Hebei, China
Muwei Dai: Orthopaedic Department, The Fourth Hospital of Hebei Medical University and Hebei Cancer Hospital, Shijiazhuang, Hebei, China
Yuling Wang: Department of Tuberculosis, The Fifth Hospital of Shijiazhuang, North China University of Science and Technology, Shijiazhuang, Hebei, China
Haiyan Kang: Department of Tuberculosis, The Fifth Hospital of Shijiazhuang, North China University of Science and Technology, Shijiazhuang, Hebei, China
Yi Xu: Department of Laboratory Medicine, The Fifth Hospital of Shijiazhuang, North China University of Science and Technology, Shijiazhuang, Hebei, China
Qian Hu: Department of Laboratory Medicine, The Fifth Hospital of Shijiazhuang, North China University of Science and Technology, Shijiazhuang, Hebei, China
Fumin Feng: School of Public Health, North China University of Science and Technology, Tangshan, Hebei, China
Bangning Cheng: Shenzhen YHLO Biotech Co., Ltd, Shenzhen, Guangdong, China
Erhei Dai: Department of Laboratory Medicine, The Fifth Hospital of Shijiazhuang, North China University of Science and Technology, Shijiazhuang, Hebei, China

DOI: https://doi.org/10.7717/peerj.15515
Journal volume & issue: Vol. 11
p. e15515

Abstract

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Background To date, several types of laboratory tests for coronavirus disease 2019 (COVID-19) diagnosis have been developed. However, the clinical importance of serum severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid antigen (N-Ag) remains to be fully elucidated. In this study, we sought to investigate the value of serum SARS-CoV-2 N-Ag for COVID-19 diagnosis and to analyze N-Ag characteristics in COVID-19 individuals. Methods Serum samples collected from 215 COVID-19 patients and 65 non-COVID-19 individuals were used to quantitatively detect N-Ag via chemiluminescent immunoassay according to the manufacturer’s instructions. Results The sensitivity and specificity of the N-Ag assay were 64.75% (95% confidence interval (95% CI) [55.94–72.66%]) and 100% (95% CI [93.05–100.00%]), respectively, according to the cut-off value recommended by the manufacturer. The receiver operating characteristic (ROC) curve showed a sensitivity of 100.00% (95% CI [94.42–100.00%]) and a specificity of 71.31% (95% CI [62.73–78.59%]). The positive rates and levels of serum SARS-CoV-2 N-Ag were not related to sex, comorbidity status or disease severity of COVID-19 (all P < 0.001). Compared with RT‒PCR, there was a lower positive rate of serum N-Ag for acute COVID-19 patients (P < 0.001). The positive rate and levels of serum SARS-CoV-2 N-Ag in acute patients were significantly higher than those in convalescent patients (all P < 0.001). In addition, the positive rate of serum SARS-CoV-2 N-Ag in acute COVID-19 patients was higher than that of serum antibodies (IgM, IgG, IgA and neutralizing antibodies (Nab)) against SARS-CoV-2 (all P < 0.001). However, the positive rate of serum SARS-CoV-2 N-Ag in convalescent COVID-19 patients was significantly lower than that of antibodies (all P < 0.001). Conclusion Serum N-Ag can be used as a biomarker for early COVID-19 diagnosis based on appropriate cut-off values. In addition, our study also demonstrated the relationship between serum N-Ag and clinical characteristics.

Published in PeerJ

ISSN: 2167-8359 (Online)
Publisher: PeerJ Inc.
Country of publisher: United States
LCC subjects: Medicine; Science: Biology (General)
Website: https://peerj.com/

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