Diagnostic Test Development
Antibodies, which are typically generated during immune responses against pathogens, provide important information related to previous infections and, dependent on the specific pathogen and antibody titer, allow conclusions regarding the protection from future infections. Diagnostic tests for antibodies are conducted either in specialized diagnostic laboratories (reference labs) or in point-of-care (POC) settings, with different advantages and disadvantages. Tests performed in reference labs excel in qualitative and quantitative performance and high-throughput capabilities, but have long turn-around times and are expensive. POC tests typically provide quick answers and are cheap, but are often not quantitative and subjective in their interpretation.
In this project, we developed an antibody diagnostics platform with (initial) focus on the identification of SARS-CoV2-specific antibodies.
OUR MAJOR OBSERVATIONS
We found that engineered, bi-specific protein molecules can be used to trigger agglutination in the presence of SARS-CoV2-specific antibodies (AB). These proteins consist (i) in a nanobody (small camelid AB) that binds red blood cells (RBC) and (ii) in part of the virus, e.g. the receptor-binding domain of the Spike protein (Spike-RBD) of SARS-CoV2 (serving as AB target). When added to finger-stick blood, this protein binds immediately RBC. If AB are present, these AB will bind Spike-RBD and lead to visually apparent agglutination.