Role of TrimericS IgG Antibodies in monitoring the immune response of recipients of COVID-19 Vaccination

COVID-19 has spurred the development of a plethora of tests from various manufacturers. While molecular tests and rapid antigen tests are targeted for early diagnosis, serology tests play a different and perhaps even larger role by supporting epidemiological studies, furthering the understanding of longitudinal immunity, and in assessing the efficacy of vaccine development. The efficient use of serology tests in understanding immunity, both in response to disease or vaccination, requires evaluation of any given assay’s diagnostic performance and discriminative ability. The spike protein has been the preferred antigen for use in vaccines, because most neutralizing antibodies are directed against this surface exposed protein on the virus that is essential for entry into human cells. Coronavirus spikes form large heavily glycosylated homo-trimeric complexes, yet due to their instability in vitro, monomeric presentations of the spike protein, including the receptor binding domain (RBD) only, have been most prevalently used in immunoassays. While the diagnostic performance of assays using RBD as an antigen have shown better results compared to spike and nucleoprotein antigens, the trimeric form was shown to be associated with greater sensitivity for the detection of SARS-CoV-2 IgG antibody in human samples. Here, the performance of the LIAISON® SARS-CoV-2 TrimericS IgG assay are described to evaluate the immune response in a population of HCWs naturally infected and after receving a complete vaccination program.

 

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