Please answer these questions in 2+ sentences, but not a paragraph1.In the “classical” cell entry of SARS-CoV-1, the Spike protein has a cleavage event by a protein in the late endosome, leading to direct fusion to the endosome membrane. In CoV-2 (COVID-19) export, some of the Spike proteins will have that same cleavage event before cell exit. Why would this lead to increased direct fusion to the cell membrane of future targets? 2.A polybasic cleavage site expands the range of proteins that can cleave a Spike protein. Why would that increase the pathogenicity of CoV-2?