Targeted proteomics as a tool to detect SARS-CoV-2 proteins in clinical specimens

The rapid, sensitive and specific detection of SARS-CoV-2 is critical in responding to the current COVID-19 outbreak. Here, we explore the potential of targeted mass spectrometry based proteomics for the detection of SARS-CoV-2 proteins in both research and clinical samples. First, we assessed the limit of detection for several SARS-CoV-2 proteins by parallel reaction monitoring (PRM) mass spectrometry. For Nucleocapsid the limit of detection was found to be in the mid-attomole range (0.9 x 10-12 g). Next, this PRM assay is applied to the detection of viral proteins in in vitro mucus substitutes, as well as in various clinical specimens such as nasopharyngeal swabs and sputum. In this proof-of-concept study SARS-CoV-2 proteins could unambiguously be detected in various clinical samples, suggesting that the sensitivity of this technology may be sufficiently high to further explore its potential role in diagnostics.