Recombinant SARS-CoV-2 Spike protein S1 subunit, encompassing amino acids 16-685. This protein corresponds to SARS-CoV2 variant B.1.617.2, also known as variant Delta originally discovered in India, and contains mutations T19R, G142D, R158G, L452R, T478K, D614G and P681R as well as deletion E156-F157. The construct also contains a C-terminal Avi-Tag™ followed by a His-tag (6xHis). The protein was affinity purified.