According to SARS CoV, various cleaved and uncleaved types of the SARS-CoV-two spike protein. Notably, the cleavage sample into the the SARS spike optimistic control from Calu3 cells, a respiratory cell line, varies a little and will signal variances between proteolytic cleavage in the spike proteins between the two viruses https://www.pinterest.com/pin/993958580252567978/