SARS-CoV-2 BA.2.75.2+K444T Omicron Variant Recombinant Spike Trimer His Tag

Concentration–response curves for binding of CoV2 spike protein to human ACE2 in cell-free ELISA-type assays. Microtiter wells were coated with 100 uL of ACE2-Fc at 2 ug/mL in PBS at 4?C overnight. The wells were washed with PBS and blocked with 200 μL of 1% BSA/PBS at RT for 1 hour. Spike trimer was serially diluted from 10 μg/mL in 1% BSA/PBS. The blocker was discarded, and the wells were incubated with 100 μL of serially diluted spike trimer at RT for 1 hour. The wells were washed with PBS and the bound spike trimer was detected with 100 μL of Peroxidase AffiniPure Rabbit Anti-His Tag (1:5, 000 in 1% BSA/PBS) at RT for 1 hour. The wells were washed with PBS and the wells were developed with 100 μL of MB/E Ultra-Sensitive, Blue, Horseradish Peroxidase Substrate at RT for 5 min. The reaction was stopped with 100 μL of 0.6N H2SO4 and the signals were read at 450 nm using a plate reader.

SARS-CoV-2 Spike Trimer, His Tag (BA.2.75.2 + K444T) on SDS-PAGE under non-reducing (NR) and reducing (R) conditions. The gel was stained with Coomassie G-250 per manufacturer instructions. The purity of the protein is greater than 95% and it is between 175 and 270 kDa.