ABSTRACT Since the D614G substitution in the spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged, the variant strain has undergone a rapid expansion to become the most abundant strain worldwide. Therefore, this substitution may provide an advantage for viral spreading. To explore the mechanism, we analyzed 18 viral isolates containing S proteins with either G614 or D614 (S-G614 and S-D614, respectively). The plaque assay showed a significantly higher virus titer in S-G614 than in S-D614 isolates. We further found increased cleavage of the S protein at the furin substrate site, a key event that promotes syncytium formation, in S-G614 isolates. The enhancement of the D614G substitution in the cleavage of the S protein and in syncytium formation has been validated in cells expressing S protein. The effect on the syncytium was abolished by furin inhibitor treatment and mutation of the furin cleavage site, suggesting its dependence on cleavage by furin. Our study pointed to the impact of the D614G substitution on syncytium formation through enhanced furin-mediated S cleavage, which might increase the transmissibility and infectivity of SARS-CoV-2 strains containing S-G614.
【저자키워드】 SARS-CoV-2, furin, spike, syncytium, 【초록키워드】 Treatment, coronavirus, Mutation, S protein, furin, variant, severe acute respiratory syndrome Coronavirus, Protein, Viral, Transmissibility, furin cleavage site, D614G, cleavage, syncytium, respiratory, mechanism, Plaque assay, isolates, virus titer, acute respiratory syndrome, acute respiratory syndrome coronavirus, acute respiratory syndrome coronavirus 2, S proteins, rapid expansion, SARS-CoV-2 strains, SARS-CoV-2 strain, D614G substitution, enhancement, syncytium formation, furin inhibitor, Cell, analyzed, promote, significantly higher, the S protein, expressing S protein, viral isolate, 【제목키워드】 titer, Substitution, enhanced, increase, Formation,