Persistent immune protein may drive long COVID

A team at MedUni Vienna has discovered that levels of the immune protein PTX-3 remain elevated in patients who experienced severe COVID-19, even months after recovery. This finding suggests PTX-3 could serve as a marker for ongoing tissue damage, prolonged immune activation, and potential post-COVID complications.

The study [1], led by Winfried Pickl and Rudolf Valenta at the Center for Pathophysiology, Infectiology and Immunology, tracked 141 COVID-19 patients up to ten months after infection. They compared acute phase protein levels with those of 98 uninfected individuals. While most immune proteins return to normal shortly after infection, PTX-3 remained unusually high in patients who had severe disease.

“This protein may indicate lingering tissue repair or the presence of residual viral components,” explained Pickl. Valenta added, “PTX-3 could help identify patients at risk of long-term complications, including chronic fatigue syndromes.”

Published in Frontiers in Immunology, the research provides new insight into long COVID mechanisms and highlights the need for further studies to understand the long-term impact of severe SARS-CoV-2 infection.

More information online

1.    Severe COVID-19 induces prolonged elevation of the acute-phase protein pentraxin 3 published in Frontiers in Immunology DOI: 10.3389/fimmu.2025.1672485