TY - JOUR T1 - Spike protein cleavage-activation mediated by the SARS-CoV-2 P681R mutation: a case-study from its first appearance in variant of interest (VOI) A.23.1 identified in Uganda JF - bioRxiv DO - 10.1101/2021.06.30.450632 SP - 2021.06.30.450632 AU - Laura E. Frazier AU - Bailey Lubinski AU - Tiffany Tang AU - Susan Daniel AU - Javier A. Jaimes AU - Gary R. Whittaker Y1 - 2021/01/01 UR - http://biorxiv.org/content/early/2021/07/01/2021.06.30.450632.abstract N2 - The African continent is currently notable as a source of novel SARS-CoV-2 variants. The A.23 viral lineage, characterized by three spike mutations F157L, V367F and Q613H, was first identified in a Ugandan prison in July 2020, and then spilled into the general population adding additional spike mutations (R102I, L141F, E484K and P681R) to comprise lineage A.23.1 by September 2020—with this virus being designated a variant of interest (VOI) in Africa and with subsequent spread to 26 other countries. The P681R spike mutation of the A.23.1 VOI is of note as it increases the number of basic residues in the sub-optimal SARS-CoV-2 spike protein furin cleavage site; as such, this mutation may affect viral replication, transmissibility or pathogenic properties. Here, we performed assays using fluorogenic peptides mimicking the S1/S2 sequence from A.23.1 and observed significantly increased cleavability with furin, compared to sequences matching Wuhan-Hu1 S1/S2. We performed functional infectivity assays using pseudotyped MLV particles harboring SARS-CoV-2 spike proteins and observed an increase in transduction for A.23.1-pseudotyped particles in Vero-TMPRSS2 and Calu-3 cells, compared to Wuhan-Hu1, and a lowered infection in Vero E6 cells. However, these changes in infectivity were not reproduced in a P681R point mutant of Wuhan-Hu1 spike. Our findings suggest that while A.23.1 has increased furin-mediated cleavage linked to the P681R mutation—which may affect viral infection and transmissibility—this mutation needs to occur on the background of other spike protein changes to enable its functional consequences.Competing Interest StatementThe authors have declared no competing interest. ER -