Detecting SARS-CoV-2 Orf3a and e Ion Channel Activity in COVID-19 Blood Samples

Yu, H. G.; Sizemore, G.; Smoot, K.; Perrotta, P.

Background: SARS-CoV-2 has been found in the heart of COVID-19 patients. It is unclear how the virus passes from the upper respiratory tract to the myocardium. We hypothesized that SARS-CoV-2 is present in the blood of COVID-19 infected patients, spreading to other organs such as heart. Methods: We targeted two viroporins, Orf3a and E, in SARS-CoV-2. Orf3a and E form non-voltage-gated ion channels. A combined fluorescence potassium ion assay with three channel modulators (4-Aminopyridine, emodin-Orf3a channel blocker, gliclazide-E channel blocker) was developed to detect SARS-CoV-2 Orf3a/E channel activity. In blood samples, we subtracted the fluorescence signals in the absence and presence of emodin/gliclazide to detect Orf3a and E channel activity. Results: In lentivirus spiked samples, we detected significant channel activity of Orf3a/E based on increase in fluorescence induced by 4-Aminopyridine, and this increase in fluorescence was inhibited by emodin and gliclazide. In 18 antigen/PCR positive samples, our test results found 15 are positive, demonstrating 83.3% concordance. In 24 antigen/PCR negative samples, our test results found 21 are negative, showing 87.5% concordance. Conclusions: We developed a cell-free test that can detect Orf3a/E channel activity of SARS-CoV-2 in blood samples from COVID-19 infected individuals, confirming a hypothesis that the virus spreads to the heart via blood circulation. © 2021 Cambridge University Press. All rights reserved.