Recombinant SARS-CoV-2 Spike protein, RBD (Receptor Binding Domain) encompassing amino acids 319-541. This protein corresponds to SARS-CoV-2 Variant B.1.617.2.1 also known as variant Delta Plus originally identified in India, and contains RBD mutations K417N, L452R and T478K. The construct contains a C-terminal Avi-Tag™ followed by a His-tag (6xHis). The protein was affinity purified. HiP™ indicates a high purity protein (≥90% pure) and less than 10% aggregation as measured by gel filtration.