Antibody tests are important tools to assess the efficacy of vaccine candidates and to derive suitable vaccination modalities. High specificity and sensitivity are of great importance for the quality of an antibody test. Over the past five months, BOKU has been working intensively on the production of various SARS CoV-2 antigens in different biotechnological production systems. The aim was to identify antigen variants for the improved detection of SARS CoV-2 antibodies and to develop sustainable production processes for their high-quality supply. In order to rapidly screen a wide range of antigen candidates generated in different expression platforms, BOKU closely collaborated with the University of Veterinary Medicine Vienna. There, all BOKU antigens were pre-assessed in ELISA assays with a panel of pre-COVID control sera and selected sera of COVID19 patients. In addition, all proteins were also tested for SARS CoV-2 antibodies with the Luminex platform at the Austrian Institute of Technology and the Medical University Vienna. Based on the immunoassay results as well as antigen production yield and suitability for process scale-up, a truncated variant of the SARS CoV-2 spike receptor-binding domain (RBD) produced in a human cell line and the viral nucleocapsid protein (NP), produced in bacteria, were selected for further assay development. BOKU established complex multi-step purification processes and analytics with multiple antigen batches to ensure that the high-quality standards required for diagnostic protein reagents are always met. For prolonged antigen and test supply, two Viennese companies, that already provided knowledge and technology in the development phase, are now commercializing the diagnostic antigens and serological tests. Technoclone GmbH optimized the ELISA protocol and now offers both the RBD and NP ELISA Test “made in Austria”. EnGenes Biotech GmbH now commercially produces and distributes SARS CoV-2 antigens. The excellent interaction between the cooperating universities, research institutions and companies in this unique cross competence approach has paid off, as the tests achieved excellent scores in clinical validations performed at the Department of Laboratory Medicine at MedUni Vienna. The tests not only allow for highly specific and sensitive detection of SARS CoV-2 antibodies, the RBD test results also correlate well with the titers of neutralizing antibodies present in sera of COVID19 patients.

Learning Objectives:

1. Quantitative SARS-CoV2 Antibody tests, basted on SARS-CoV2 receptor binding domain and highly pure nucleocapsid protein for vaccination monitoring

2. Antigen quality assessment compared with both ELISA and LUMINEX in over 2000 sampels

3. Increased Specificity and Sensitivity by applying a combined two test strategy