Research tools for Covid-19
Research on SARS-CoV-2 is currently a key concern of life sciences to prevent further infections and to develop a vaccine. The following studies as well as the antigen specific FluoroSpot method demonstrate the great utility of the Strep-tag® technology in this area. It can be used for the isolation of cells and exosomes or for affinity purification of proteins, but moreover Strep-Tactin®XT proves to be particularly good for the immobilization and detection of viral proteins due to its high affinity for the Twin-Strep-tag®.
Detection of Memory B cells specific for SARS-CoV-2 with reversed antigen specific IgG FluoroSpot
The Swedish biotech company Mabtech showed that reversed antigen specific FluoroSpot is a valid method for testing human B cell memory response, which could be an interesting complement for studying long term immunity of COVID-19.
In their study they immobilized their anti-human IgG (MT91/145) capture antibodies in a FluoroSpot plate. For detection of IgGs specific to a receptor binding protein (RBD) of the SARS-CoV-2 Spike protein, the RBD was fused with a C-terminal Twin-Strep-tag® that subsequently was detected with a Strep-Tactin® XT conjugated to a 550-fluorophore. They decided to recombinantly express the Twin-Strep-tag® together with the RBD protein instead of traditional biotinylation, because biotinylation of lysines might interfere with immunogenic epitopes. More information about the method can be found here.