VIRCoV

The acute SARS-CoV-2 infection is diagnosed routinely through PCR-based detection of viral RNA from nasopharyngeal swabs. Additionally, direct antigen detection of viral proteins is now available. The specific detection by PCR has a high sensitivity and specificity but delivers a false-negative rate of up to 38 % at the time of symptoms (Kucirka et al. 2020). The sensitivity and specificity of antigen detection tests are lower than PCR-based detection caused by methodology (CDC, Guidelines, August 1, 2020).

Besides the direct detection of an acute infection through PCR, the measurements of antibodies against the virus are commercially available, which quantify SARS-CoV-2 specific IgG and IgM antibodies in blood of patients to determine whether a patient had already contact to the virus and might have some kind immunity.

However, all these test systems do not provide any information which organs have been infected and potentially damaged through SARS-Cov-2 such as lungs, brain, heart, kidney and endothelium. This information is of significant clinical importance because Covid-19 disease with mild symptoms can lead to tremendous organ damages. The extrapulmonary spread of a SARS-CoV-2 infection causes the organ damages and are decisive for the course and recovery from Covid-19 disease (Gupta et al. 2020, Extrapulmonary manifestations of Covid-19, Review in Nature Medicine). Myocardial damages will occur in 20-30 % of hospitalized Covid-19 patients, in patients with pre-existing myocardial diseases even in 55 % of cases (Guo et al. 2020). In a study of 5.500 Covid-19 patients acute kidney injuries were diagnosed in 37 % of cases, 14 % of patients required dialysis (Hirsch et al. 2020).

In Germany, 16% of confirmed SARS-CoV-2 infected individuals were hospitalized because of Covid-19 disease according to a report of the Robert-Koch-Institutes dated 29-July-2020. There is a „high unmet medical need“, not only to diagnose SARS-CoV-2 with high sensitivity and specificity, but also to gain information about the spread and damage of extrapulmonary manifestation of Covid-19 disease in order to initiate specific targeted treatments, disease monitoring and follow-up schemes.  Also once the SARS-CoV-2 pandemic has been defeated and overcome, next pandemic might occur in the near future, and tests to analyze the organ damage and involvement, is of high need for pandemic preparedness.

VIR-CoV-S is a novel, state-of-art test, to detect and localize infected organs during acute Covid-19 disease delivering highly valuable information to clinicians, transferable and applicable to other viral infections.

The option to diagnose SARS-CoV-2 infections are PCR-based and antigen-based assays sampled from nasopharyngeal swabs. All these test systems do not provide any information where the virus replicates and which organs have been infected and potentially damaged through SARS-Cov-2 such as lungs, brain, heart, kidney and endothelium. These information are of significant clinical value because Covid-19 disease with mild symptoms can lead to tremendous organ damages.

The extrapulmonary spread of a SARS-CoV-2 infection is causing organ damages and is decisive for the course and recovery from Covid-19 disease (see also section 2.3). In order to initiate disease tailored therapies (for example myocardial insufficiencies because of heart damage) and specific monitoring (for example if known that the kidney has been affected) to follow-up of the patients. Such a test system is not available.

Virus-infected cells release exosomes carrying virus protein on their surface. In proof-of-concept studies we demonstrated by means of fluorescence flow cytometry that ExoMag-positive extracellular vesicles carry SARS-CoV-2 spike protein on their surface (see Figure below). For the first time we show applying our methodology that extracellular vesicles released from infected cells in blood of Covid-19 patients contain SARS-CoV-2 protein.

Legend: Detection of SARS-CoV-2 spike antigen on exosomes in blood of Covid-19 patients (right upper quadrant). Both Covid-19 patients were tested PCR positive Control show the upper right quadrant empty.

Our technology enables to identify exosomes released from infected organs by applying organ-specific markers. Thus, we can diagnose the affected organs such as heart, endothelium or kidney and provide this information to clinicians to initiate appropriate treatment or monitoring follow-up.

Our developed method forms the basis of VIR-CoV, to determine through high-resolution phenotyping of SARS-CoV-2 microvesicles the localization of infected organs during acute Covid-19 disease.

By means of flow cytometry analysis of SARS-CoV-2 carrying exosomes, we will apply antibodies, to identify the origin e.g. which cells and organs released these exosomes (see Figure below).

Legend: Schematic presentation of the approach: SARS-CoV-2 infected various organs (left), which released exosomes with specific cell surface markers. Simultaneous detection of SARS-CoV-2 on exosomes and organ-specific markers will enable to identify the infected organs during Covid-19 disease (right). 

VIR-CoV is novel and currently unique and would provide the clinicians with these highly valuable and potentially lifesaving information.