Fig. 6. 3-D structure protein S of the COVID-19.

a The position of aspartate 614 is conserved among species, until the D-G mutation occurred in the virus variant now dominant in the European and American countries of the pandemic occurred. The D614G mutation generates an additional elastase proteolytic cleavage site that enhances viral membrane fusion next to the S1–S2 junction site (685) (modidfied from Bhattacharyya et al.)⁶⁰. b Frequency of the D614/G mutation in the S-protein of COVID-19 in the S-protein sequences available in the GenBank from January to May, 2020. (modified from Zhang et al.)⁶¹.