**2.1 D614G variant**

At the beginning of February, a new strain of the disease began to spread in Europe, and the first species to rapidly dominate the world was the D614G strain, which underwent a change in the S protein and caused the disease to become more infectious, but still, It was treatable by neutralizing with recovery serum [13]. This species rapidly replaced the original and weaker species, a mutation that increased replication capacity and sensitivity in both human and animal models. SG614 is more steady than SD641 and less S1 shedding is noticed, so the SARS-CoV-2 with SG614 could transmit more efficiently. One review shows that in different cell lines, the SARS-CoV-2 containing the D614G change is eight times more effective at transducing cells than wild-type spike protein, providing evidence that the D614G mutation in SARS-CoV-2 spike protein could increase the transduction of multiple human cell types. TheD614G in the furin binding is a conspicuous common mutation depicted in nearly all of the new variations. The D614G mutation could decrease neutralization sensitivity to the sera of convalescent COVID-19 patients [11, 13, 14].
