Immune Netw.  2021 Feb;21(1):e11. 10.4110/in.2021.21.e11.

Sputum Processing Method for Lateral Flow Immunochromatographic Assays to Detect Coronaviruses

  • 1College of Pharmacy, Korea University, Sejong 30019, Korea
  • 2Department of Microbiology, Chungbuk National University, Cheongju 28644, Korea
  • 3Korea Research Institute of Bioscience and Biotechnology, Daejeon 34113, Korea
  • 4College of Healthcare & Biotechnology, Semyung University, Jecheon 27136, Korea
  • 5Korea Zoonosis Research Institute, Chonbuk National University, Iksan 54531, Korea
  • 6College of Veterinary Medicine, Chonnam National University, Gwangju 61186, Korea
  • 7Animal Medical Institute, Chonnam National University, Gwangju 61186, Korea


Coronavirus causes an infectious disease in various species and crosses the species barriers leading to the outbreak of zoonotic diseases. Due to the respiratory diseases are mainly caused in humans and viruses are replicated and excreted through the respiratory tract, the nasal fluid and sputum are mainly used for diagnosis. Early diagnosis of coronavirus plays an important role in preventing its spread and is essential for quarantine policies. For rapid decision and prompt triage of infected host, the immunochromatographic assay (ICA) has been widely used for point of care testing. However, when the ICA is applied to an expectorated sputum in which antigens are present, the viscosity of sputum interferes with the migration of the antigens on the test strip. To overcome this limitation, it is necessary to use a mucolytic agent without affecting the antigens. In this study, we combined known mucolytic agents to lower the viscosity of sputum and applied that to alpha and beta coronavirus, porcine epidemic diarrhea virus (PEDV) and Middle East respiratory syndrome coronavirus (MERS-CoV), respectively, spiked in sputum to find optimal pretreatment conditions. The pretreatment method using tris(2-carboxyethyl)phosphine (TCEP) and BSA was suitable for ICA diagnosis of sputum samples spiked with PEDV and MERS-CoV. This sensitive assay for the detection of coronavirus in sputum provides an useful information for the diagnosis of pathogen in low respiratory tract.


Coronavirus; Diagnosis; Sputum; Chromatography; Sensitivity
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