(B) Magnification of the S1 ectodomain (glycans removed for clarity) the RBD in the up conformation is responsible for binding ACE2. (A) Overall architecture of the complex between S protein (prefusion conformation, cyan) and ACE2 (violet) glycans on S protein are in van der Waals spheres the relative positions of the plasma and viral membranes are reported. The S protein is the first promoter of SARS-CoV-2 internalization. The SARS-CoV-2 strain shows a selective affinity for the angiotensin-converting enzyme 2 (ACE2, Figure 1A) receptor, a type 1 transmembrane protein with an external peptidase domain (PD) normally responsible for the conversion of angiotensin hormone into angiotensin II. It characterizes the shape of this family of viruses, giving it the “solar” crown aspect they are named after. The SARS-CoV-2 infection mechanism depends on the transmembrane spike protein (S protein, Figure 1A,D), a highly conserved structure amongst the coronaviridae family responsible for extracellular binding and cell membrane fusion. Coronaviridae viruses are responsible for cardiovascular, hepatic, respiratory, gastrointestinal, and neurological diseases, with major symptoms associated with a hyperbolic expression of proinflammatory signals and cytokines such as interleukins, interferon-gamma (IFN-γ), IFN-γ induced protein 10 (IP-10), macrophage inflammatory protein 1A and 1B (MIP-1A, MIP1-B), platelet-derived growth factor (PDGF), tumor necrosis factor (TNF-α), and vascular endothelial growth factor (VEGF). Coronaviridae is an enveloped positive-stranded, non-segmented RNA virus with a genome of about 30 kb. The year 2019 signaled the start of the worldwide outbreak of Coronavirus disease (Covid-19) from the Coronaviridae SARS-CoV-2 virus, which counts around 360 million cases around the world with more than 5.6 million certified deaths (WHO dashboard, January 27, 2022).

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