Abstract
BackgroundSerological assays for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) have roles in seroepidemiology, convalescent plasma-testing, antibody durability and vaccine studies. Currently, SARS-CoV-2 serology is performed using serum/plasma collected by venepuncture. Dried blood spot (DBS) testing offers significant advantages as it is minimally invasive, avoids venepuncture with specimens being mailed to the laboratory.MethodsA pathway utilizing a newborn screening laboratory infrastructure was developed using an enzyme-linked immunosorbent assay to detect IgG antibodies against the receptor-binding domain of the SARS-CoV-2 spike protein in DBS specimens. Paired plasma and DBS specimens from SARS-CoV-2 antibody-positive and -negative subjects and polymerase chain reaction positive subjects were tested. DBS specimen stability, effect of blood volume and punch location were also evaluated.ResultsDBS specimens from antibody-negative (n = 85) and -positive (n = 35) subjects and polymerase chain reaction positive subjects (n = 11) had a mean (SD; range) optical density (OD) of 0.14 (0.046; 0.03–0.27), 0.98 (0.41; 0.31–1.64) and 1.12 (0.37; 0.49–1.54), respectively. An action value OD >0.28 correctly assigned all cases. The weighted Deming regression for comparison of the DBS and the plasma assay yielded: y = 0.004041 + 1.005x, r = 0.991, Sy/x 0.171, n = 82. Extraction efficiency of antibodies from DBS specimens was >99%. DBS specimens were stable for at least 28 days at ambient room temperature and humidity.ConclusionsSARS-CoV-2 IgG receptor-binding domain antibodies can be reliably detected in DBS specimens. DBS serological testing offers lower costs than either point of care or serum/plasma assays that require patient travel, phlebotomy and hospital/clinic resources; the development of a DBS assay may be particularly important for resource poor settings.
Highlights
Serological testing for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is important clinically, in the selection of convalescent plasma donors, understanding durability of antibody responses, to assess the impact of a second or subsequent surge, to monitor antibody production when vaccines become available and in seroprevalence studies
We propose Dried blood spot (DBS) testing for anti-SARS-Cov-2 antibodies using a ‘kit’ containing instructions on using a lancet to obtain capillary blood, a blood spot filter paper collection device and a return mail envelope, this would enable testing without an appointment or the need to travel to a health-care facility
We describe the systematic optimization of the elution of SARS-CoV-2 receptor-binding domain (RBD) IgG antibodies from DBS specimens for analysis using an optimized inhouse high-throughput enzyme-linked immunosorbent assay (ELISA)
Summary
Serological testing for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is important clinically, in the selection of convalescent plasma donors, understanding durability of antibody responses, to assess the impact of a second or subsequent surge, to monitor antibody production when vaccines become available and in seroprevalence studies. Serological assays for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) have roles in seroepidemiology, convalescent plasma-testing, antibody durability and vaccine studies. Methods: A pathway utilizing a newborn screening laboratory infrastructure was developed using an enzyme-linked immunosorbent assay to detect IgG antibodies against the receptor-binding domain of the SARS-CoV-2 spike protein in DBS specimens. Paired plasma and DBS specimens from SARS-CoV-2 antibody-positive and -negative subjects and polymerase chain reaction positive subjects were tested. DBS serological testing offers lower costs than either point of care or serum/plasma assays that require patient travel, phlebotomy and hospital/clinic resources; the development of a DBS assay may be important for resource poor settings
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