SARS-CoV-2 is a member of the betacoronavirus genus and is closely related to SARS-CoV (Wrapp et al. 2020). In general, three structural proteins are associated with the viral envelope of corona viruses: a membrane protein (M), an envelope protein (E) and a spike protein (S). The spike protein consists of three segments: an ectodomain (including subunits S1 and S2), a transmembrane anchor and a short intracellular tail. The trimeric transmembrane spike glycoprotein (S) mediates the coronavirus entry by receptor binding and membrane fusion. It consists of two functional subunits named S1 and S2. S1 mediates binding to the host receptor and shows a high diversity among corona viruses. S2 induces fusion of the virus with the cellular membrane of the host and is conserved.