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Distinct immune response identified in the early phase of SARS CoV-2 infection

Clear distinction from other viral diseases of the respiratory tract
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(Vienna, 21 September 2021) Infection with the SARS-CoV-2 virus leads to a unique response from the human immune system: a distinct pattern of immunological markers, unlike that of other viral respiratory diseases, is present in the blood of SARS-CoV-2 patients. This was shown in a recent study funded by the Medical Science Fund of the Mayor of the City of Vienna and conducted by an interdisciplinary team led by Klaus Schmetterer, Robert Strassl (both Department of Laboratory Medicine) and Johannes Kovarik (Department of Medicine III) at MedUni Vienna and Vienna General Hospital. The study has now been published in the leading journal “Frontiers in Cellular and Infection Microbiology”.

Due to an overreaction of the immune system, infection with SARS-CoV-2 can lead to a severe clinical course of disease, potentially including multiple organ failure. Schmetterer explains: "This has already been shown in multiple studies, but the problem with it was that the previous data could only be obtained at a later stage of the disease from seriously ill patients in intensive care units. Data from the early phase of COVID-19 infection and appropriate control groups were often lacking. Therefore, it has been largely unclear whether the immune system responds differently to SARS-CoV-2 in the early post-infection period than it does to the known seasonal respiratory viruses."

In order to better define the immune response to SARS-CoV-2, the interdisciplinary team used a cohort of outpatients who visited the University Hospital Vienna with typical symptoms of a viral respiratory infection. "These patients presented with the typical symptoms that can occur during SARS-CoV-2 infection, but also with other viral respiratory infections (e.g. fever, shortness of breath, cough,…). For the purposes of this study, we deliberately selected patients who visited the Vienna General Hospital within the first two days after the onset of symptoms and had no known pre-existing conditions," explains Robert Strassl.

Based on PCR test results, the patients were divided into a COVID-19 positive group and a COVID-19 negative group, i.e. patients with other infections. The researchers additionally included a third comparison group of healthy subjects.  For the study, all groups were tested for a total of 65 immune markers in blood plasma. This provided a detailed insight into the complex immunological processes of SARS-CoV-2 infection: "We were actually able to define four messenger substances (NB: BLC, sCD30, MCP-2 and IP-10) that are elevated in the blood of patients in the early phase following infection with SARS-CoV-2 but not in other viral infections," says the first author of the study, Johannes Kovarik. Firstly, the results of these investigations could provide starting points for future therapeutic approaches for Covid-19, and secondly, the new findings could also constitute important comparative parameters for further studies, for example on chronic forms of the disease such as "Long COVID".

Service: Frontiers in Cellular and Infection Microbiology

"Identification of Immune Activation Markers in the Early Onset of COVID-19 Infection." Johannes J. Kovarik, Anna K. Kämpf, Fabian Gasser, Anna N. Herdina, Monika Breuer, Christopher C. Kaltenecker, Markus Wahrmann, Susanne Haindl, Florian Mayer, Ludwig Traby, Veronique Touzeau-Roemer, Katharina Grabmeier-Pfistershammer, Manuel Kussmann, Oliver Robak, Harald Willschke, Care Ay, Marcus D. Säemann, Klaus G. Schmetterer and Robert Strassl. Front. Cell. Infect. Microbiol., 03 September 2021;