SARS-CoV-2 spike glycoprotein, Delta variant (SARS-CoV-2 S (Delta))

The SARS-CoV-2 spike glycoprotein (Delta variant) is a large, heavily glycosylated trimeric transmembrane protein that forms the characteristic spikes decorating the coronavirus surface[1][2][3][5][7][8]. As a class I viral fusion protein, it mediates viral attachment and fusion to host cells by binding to the angiotensin-converting enzyme 2 (ACE2) receptor and orchestrating fusion of viral and host membranes[1][3][7]. It consists of two major subunits: S1, containing the N-terminal domain and receptor binding domain (RBD, which attaches to ACE2), and S2, responsible for membrane fusion[1][7]. The Delta variant (B.1.617.2) contains specific mutations in its spike protein that enhance binding affinity for ACE2, facilitate open conformations for binding, and contribute to immune evasion relative to previous variants[3][5]. This protein is the main antigenic determinant and therapeutic/vaccine target for COVID-19, with all currently approved vaccines and most neutralizing antibodies targeting the spike[6][8]. The Delta spike has altered glycosylation and amino acid composition compared to other variants but retains the core functions of receptor binding and membrane fusion[5]. Blockade or neutralization of the spike protein by antibodies or inhibitors can prevent viral entry, making it a validated antiviral target. High variability in the spike impacts vaccine and antibody therapy effectiveness, presenting a challenge for therapeutic targeting and population immunity[3][5].

Other names

Spike protein (Delta variant)S protein (Delta variant)SARS-CoV-2 S glycoprotein (B.1.617.2)COVID-19 spike protein (Delta)

Inhibition of spike-ACE2 interaction (entry blockade); Neutralization of the spike’s receptor binding domain (RBD); Prevention of membrane fusion