In a promising step toward understanding Long COVID, researchers have identified fragments of viral proteins that continue to be present in the blood of affected patients, providing perhaps the first measurable biomarker for this complex condition.
Scientists from the Translational Genomics Research Institute and the Lundquist Institute found these fragments, which come from the virus's RNA replicase enzyme, inside small cellular carriers called extracellular vesicles. These "ghost" proteins were not present in pre-pandemic control samples, suggesting that SARS-CoV-2 may remain hidden in reservoirs in the body long after the initial infection has cleared.
The study, published in the journal Infection, analyzed blood samples from patients enrolled in a long-term study of exercise after COVID. Although not all blood samples revealed viral remnants, the repeated detection of SARS-CoV-2 fragments suggests a persistent molecular footprint that could help explain symptoms such as fatigue, mental fog, and worsening of symptoms after exercise.
The researchers caution that more work is needed to determine whether these fragments indicate ongoing viral activity or are simply cellular debris. However, the results offer a potential breakthrough in diagnostics and a clearer biological window into one of the most mysterious consequences of COVID-19.
