Study identifies biomarker to detect persistent Covid

A study led by Cambridge university (UK) identifies interferon gamma protein (IFN-y) as a potential biomarker of persistent Covid fatigue and highlights an immune mechanism underlying the disease, which could pave the way for the development of much-needed treatments and provide an advantage in the event of a future coronavirus pandemic.

“We have found a potential mechanism underlying Long Covid, which may represent a biomarker, that is, a characteristic sign of the disease.”

Research published in Science achievements

, followed a group of patients with persistent Covid fatigue for more than two and a half years to understand why some recovered and others did not. Study shows that infection initial with SARS-CoV-2 It triggers the production of the antiviral protein IFN-y, which is a normal response of the immune system.

In most people, when the infection clears, Covid-19 symptoms stop and production of this protein stops, but researchers have found that high levels of IFN-y persist in some long Covid patients for up to 31 months.

“We hope this will help pave the way for the development of treatments and give some patients an accurate diagnosis.”“

“We have found a potential mechanism underlying Long Covid, which may represent a biomarker, that is, a characteristic sign of the disease. We hope this will help pave the way for the development of treatments and provide some patients with an accurate diagnosis.“comments the co-author, Dr. Benjamin Krishnafrom the Cambridge Institute of Therapeutic Immunology and Infectious Diseases (CITIID).

The team studied 111 confirmed Covid patients admitted to Addenbrooke’s CUH, Royal Papworth Hospital and Cambridge and Peterborough NHS Foundation Trust at 28, 90 and 180 days after symptom onset.

Between August 2020 and July 2021 they recruited 55 Long Covid patients (all with severe symptoms at least 5 months after acute Covid-19) who attended the Long Covid clinic at Addenbrooke’s.

‘It is unlikely that all the different symptoms of long Covid are caused by the same thing’

The researchers analyzed the blood samples for signs of cytokines, small proteins critical to the functioning of the immune system and blood cells.

They found that white blood cells from people infected with SARS-CoV-2 produce IFN-y, a pro-inflammatory molecule, and that this persists in patients with persistent Covid. Having completed cell depletion assaysThe team was able to identify the exact cell types responsible for producing IFN-y.

“Some patients recover slowly, and there are others who remain trapped in the fatigue cycle for years.”

They identified immune cells known as CD8+ T cells, but found that they required contact with another type of immune cell: CD14+ monocytes. The Cambridge team followed a group of long Covid patients for 31 months after infection. During this follow-up period, more than 60% of patients experienced resolution of some, if not all, symptoms, coinciding with a decrease in IFN-γ levels.

In addition, the team measured IFN-y release in patients with persistent Covid before and after vaccination and found a significant reduction in post-vaccination IFN-y in patients whose symptoms resolved.

Thus, this study argues that the presence of IFN-y can be used to classify persistent Covid into subtypes that can be used to personalize treatment.

“It is unlikely that all the different symptoms of long Covid are caused by the same thing. We need to differentiate between people and individual treatment. Some patients recover slowly, while there are others who remain trapped in the fatigue cycle for years. We need to know why“The researchers conclude.