Prediction of Post-Acute-Sequelae of COVID-19 by Cargo Protein Biomarkers of Blood Total Extracellular Vesicles in Acute COVID-19

Background: SARS-CoV-2 invades mitochondria of infected cells resulting in disordered metabolism, mitophagy, and abnormal levels of mitochondrial proteins in extracellular vesicles. Blood extracellular vesicle SARS-CoV-2 proteins and mitochondrial proteins were quantified in COVID-19 to assess possible roles as biomarkers.

Methods: Total extracellular vesicles were precipitated from blood of age- and gender-matched participants with no infection (n=10), acute COVID-19 (n=16), post-acute sequelae of COVID-19 (PASC or long COVID) (n=30), or post-acute COVID without PASC (n=8) and their extracted proteins quantified by enzyme-linked immunosorbent assays (ELISAs).

Results: Total extracellular vesicle levels of S1 (receptor-binding domain [RBD]) protein were significantly higher in acute infections than in uninfected controls, post-acute infection without PASC, and PASC. Total extracellular vesicle levels of nucleocapsid (N) protein were significantly higher in PASC than in uninfected controls, acute infections, and post-acute infection without PASC. Neither acute levels of S1(RBD) or N proteins predicted progression to PASC. Levels of neither SARS-CoV-2 protein in established PASC correlated with neuropsychiatric manifestations. Significant decreases in total extracellular vesicle levels of the mitochondrial proteins MOTS-c, VDAC-1, and humanin, and elevations of levels of SARM-1 were observed in acutely infected patients who would develop PASC. Significant decreases in total extracellular vesicle levels of MOTS-c and humanin, but not VDAC-1, and elevations of total extracellular vesicle levels of SARM-1 were characteristic of PASC patients with neuropsychiatric manifestations.

Conclusions: Total extracellular vesicle levels of SARS-CoV-2 proteins in COVID-19 indicate intracellular presence of SARS-CoV-2. Abnormal total extracellular vesicles levels of mitochondrial proteins in acute infections predict a high risk of PASC and later in established PASC are indicative of neuropsychiatric manifestations.