Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an enveloped, positive-sense, single-stranded RNA virus that causes coronavirus disease 2019 (COVID-19). The structural proteins of SARS-CoV-2 include the envelope protein (E), spike or surface glycoprotein (S), membrane protein (M) and the nucleocapsid protein (N). The spike glycoprotein is found on the outside of the virus particle and gives coronavirus viruses their crown-like appearance. Spike glycoprotein is cleaved into the following 3 chains, Spike protein S1, Spike protein S2, Spike protein S2'.

Spike protein S1 attaches the virion to the cell membrane by interacting with host receptor, initiating the infection. Binding to human ACE2 receptor and internalization of the virus into the endosomes of the host cell induces conformational changes in the Spike glycoprotein. Uses human Transmembrane Serine Protease 2 (TMPRSS2) for priming in human lung cells which is an essential step for viral entry. Surface glycoprotein is an important target for vaccine development, antibody therapies and diagnostic antigen-based tests.