SARS-CoV-2 Delta B.1.617.2 Variant Recombinant Spike Trimer His Tag

Coronaviruses belong to a large family of protein enveloped positive-strand RNA viruses that are known to cause upper respiratory, gastrointestinal, central nervous system diseases in animals and human (1). One of the main proteins on viral envelop is a heavily glycosylated spike (S) protein (2). Trimeric S protein is involved in host receptor angiotensin-converting enzyme 2 (ACE2) recognition and mediates viral entry into cells. It is the principle antigenic determinant of neutralizing antibodies (3). S protein is recognized by humoral immune response during infection leading to inflammatory response. Homotrimeric S protein is a class I fusion protein that forms large protrusions from the virus surface and undergoes a significant structural rearrangement to fuse the viral membrane with the host-cell membrane once it binds to the host receptor (4).