Mass-Spectrometric Detection of SARS-CoV‑2 Virus in Scrapings of the Epithelium of the Nasopharynx of Infected Patients via Nucleocapsid N Protein

• Published in: Journal of proteome research Vol. 19; no. 11; pp. 4393 - 4397
• Main Authors: Nikolaev, Evgeny N, Indeykina, Maria I, Brzhozovskiy, Alexander G, Bugrova, Anna E, Kononikhin, Alexey S, Starodubtseva, Natalia L, Petrotchenko, Evgeny V, Kovalev, Grigoriy I, Borchers, Christoph H, Sukhikh, Gennady T
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 06.11.2020
• Subjects: Betacoronavirus - chemistry; Clinical Laboratory Techniques - methods; Communication; Coronavirus Infections - diagnosis; Coronavirus Infections - virology; Coronavirus Nucleocapsid Proteins; COVID-19; COVID-19 infection; COVID-19 Testing; diagnostic techniques; digestion; Humans; isopropyl alcohol; mass spectrometry; Mass Spectrometry - methods; mucosa; Nasal Mucosa - virology; nasopharynx; Nasopharynx - virology; nucleocapsid; Nucleocapsid Proteins - analysis; pandemic; Pandemics; patients; Peptide Fragments - analysis; Peptide Fragments - chemistry; peptides; Phosphoproteins; Pneumonia, Viral - diagnosis; Pneumonia, Viral - virology; polymerase chain reaction; proteolysis; proteome; Proteomics; RNA; saliva; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Viral Load; viruses; COVID-19; mass-spectrometry; proteomics; SARS-COV-2; TIMS-TOF PRO
• ISSN: 1535-3893; 1535-3907; 1535-3907
• DOI: 10.1021/acs.jproteome.0c00412

The detection of viral RNA by polymerase chain reaction (PCR) is currently the main diagnostic tool for COVID-19 ( Eurosurveillance 2019, 25 (3), 1 ). The PCR-based test, however, shows limited sensitivity, especially in the early and late stages of disease development ( Nature 2020, 581, 465−469 ; J. Formosan Med. Assoc. 2020, 119 (6) 1123 ), and is relatively time-consuming. Fast and reliable complementary methods for detecting the viral infection would be of help in the current pandemic conditions. Mass spectrometry is one of such possibilities. We have developed a mass-spectrometry-based method for the detection of the SARS CoV-2 virus in nasopharynx epithelial swabs based on the detection of the viral nucleocapsid N protein. Our approach shows confident identification of the N protein in patient samples, even those with the lowest viral loads, and a much simpler preparation procedure. Our main protocol consists of virus inactivation by heating and the addition of isopropanol and tryptic digestion of the proteins sedimented from the swabs followed by MS analysis. A set of unique peptides, produced as a result of proteolysis of the nucleocapsid phosphoprotein of SARS-CoV-2, is detected. The obtained results can further be used to create fast parallel mass-spectrometric approaches for the detection of the virus in the nasopharyngeal mucosa, saliva, sputum and other physiological fluids.