Dried blood spots (DBS) collected from the fingertip yield reliable results in analysis of anti-SARS-CoV-2 antibodies, even after prolonged storage of DBS eluates for 6 to 8 hours. This was demonstrated in a recently published study from MVZ Labor Krone GbR in Bad Salzuflen, Germany, in collaboration with EUROIMMUN and further institutions.
DBS are an easy-to-collect sample material and thus beneficial in epidemiological studies and individual immune status enquiries. The suitability of DBS for anti-SARS-CoV-2 antibody determination was assessed by comparing results from DBS eluates with those from serum, the gold standard.
121 volunteers gave both venous and capillary blood samples. The venous blood was withdrawn by a medical professional, while the capillary blood was collected via self-sampling under supervision. The capillary blood was applied directly from the fingertip onto DBS cards, with participants instructed to fill at least two circles per card. At the diagnostic laboratory, the spots were automatically punched into deep-well plates and then eluted. Antibodies in the DBS eluates were measured either immediately or after a storage period of 6 to 8 hours at room temperature. All samples were analysed for IgG antibodies against SARS-CoV-2 spike protein 1 (S1) and nucleocapsid protein (NCP) using EUROIMMUN ELISAs processed automatically on the EUROLabWorkstation ELISA.
Results from the DBS analysis showed a high correlation with the serum values for both anti-S1 and anti-NCP antibodies (r=0.96). After storage of DBS eluates for 6 to 8 hours, the correlation remained high (r=0.97 and r=0.93, respectively). These results thus indicate a high stability of anti-SARS-CoV-2 IgG levels in DBS eluates for at least several hours.
The publication concludes that DBS are suitable for analysis of anti-SARS-CoV-2 S1 and -NCP antibodies and are an easy-access tool for data collection for serological surveillance. The minimally invasive DBS sampling offers a major advantage over venous blood withdrawal, while providing comparable quality. The dried blood card, which is now available from EUROIMMUN, is CE-marked as a volumetric sample collection device with defined blood volumes per area. The EUROIMMUN ELISAs used in this study are CE-marked for use with DBS samples. EUROIMMUN’s quantitative anti-S1 antibody test, the Anti-SARS-CoV-2 QuantiVac ELISA (IgG), is also validated for DBS.
Serological diagnostics based on DBS are now being extended to further EUROIMMUN assays, with the aim of simplifying diagnostic testing and disease surveillance. The analytical applications for DBS include infection, autoimmune and allergy parameters.
Read more about the use of DBS for anti-SARS-CoV-2 antibody testing in the Journal Biochemistry and Biophysics Reports
Guttmann S. et al. Dried blood spot eluates are suitable for testing of SARS-CoV-2 antibodies targeting spike protein 1 and nucleocapsid protein. Biochem Biophys Rep 34 (2023) 101479.https://doi.org/10.1016/j.bbrep.2023.101479
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