Detection of anti-SARS-CoV-2 antibodies

The unprecedented coronavirus disease 2019 (COVID-19) has required versatile and highly adapted diagnostic and analytical tools to understand and manage the pandemic. After a series of unexplained cases of pneumonia occurred in Wuhan, China in December 2019, the target pathogen for severe respiratory syndrome corona virus 2 (SARS-CoV-2) was easily identified and genetically characterized.

1 , 2 and only about 12 months later the first3 of several promising candidate vaccines passed the approval procedures4-7 in several countries. Nevertheless, the still high/increasing number of infections and the appearance of new, rapidly spreading variants8-11 have pushed health systems to their limits, and the search for proportionate but adequate measures to combat the pandemic and its consequences. world has been of paramount importance. extraordinary complexity.

To date, various analytical testing procedures are approved and available, including molecular antigen detection (nucleic acid testing, NAT) as well as a versatile range of serological tests (antibody detection). The transcription-polymerase chain reaction (RT-PCR)13, 14 test is the gold standard for confirming SARS-CoV-2 infection. In addition, rapid test methods such as Lateral Flow Immunoassays (LFIA) have been introduced for various purposes, e.g. for access control to sensitive areas.

15,16 Complementary serological testing methods can be applied to supplement standard RT-PCR testing to cover false negative results due to decreased virus shedding in the area respiratory sampling.17 In addition, these techniques are highly valuable for detecting the humoral response in the form of immunoglobulins (mainly IgG and/or IgM), which allow the monitoring of the virus in case of epidemiological studies and support analyzes of follow-up on the effectiveness of the vaccination programs initiated.

The aforementioned immune response to SARS-CoV-2 exposure is described as successive antibody formation, first presenting IgM (after 3-7 days) followed by the long-term presence of IgG (after 7-25 days). The absolute intensity of antibody production is known to be correlated with clinical severity,15, 17 and whether or not IgG and its concentration indicate potential immunity has been the subject of ongoing debate.

Here, a routine procedure contributing to comprehensive anti-SARS-CoV-2 antibody testing from dried blood spots (DBS) is presented as a continuation of previous studies.18-22 The use of DBS as a matrix This alternative offers obvious advantages as no-one-contact for invasive venipuncture is required and specimen transport and storage is greatly facilitated by courier delivery and ambient temperature conditions.

Due to their design and properties, enzyme immunoassays (ELISAs) and CLIAs are suitable screening methods for testing larger populations in a short time. (elite) sports testing and research projects, using manual sample preparation as well as automated DBS sample extraction. The feasibility and utility of automated DBS extraction23-26 has been reported in various applications, including SARS-CoV-2 antibody testing.