A lesser-known SARS-CoV-2 protein may offer clues to long COVID symptoms

A new UCLA study published in Science Advances reveals that a previously unidentified SARS-CoV-2 protein may hold clues to long COVID symptoms. The protein in question, the nucleocapsid protein, is responsible for packaging and protecting the virus's genetic material. Scientists led by virologist Melody Li discovered that this protein can have both suppressive and amplifying effects on the immune system, depending on the stage of infection.

While it initially dampens the body's early antiviral defenses, it later amplifies inflammatory pathways, which can lead to tissue-damaging immune responses. This double-edged sword behavior was found to be consistent across several SARS-CoV-2 variants, including the highly inflammatory delta variant. The researchers also found that macrophages, immune cells that patrol tissues for signs of infection, release inflammatory signals when exposed to signals from macrophages producing the delta variant's nucleocapsid protein.

These signals can disrupt coronary endothelial barriers, potentially explaining cardiac injury seen in severe COVID-19 cases. This discovery opens up possibilities for more targeted treatments for COVID-19, as well as insights into similar mechanisms in future coronavirus outbreaks.