Biochemical Basis for Increased Activity of Ebola Glycoprotein in the 2013–16 Epidemic

Ebola virus (EBOV) infection is characterized by sporadic outbreaks caused by zoonotic transmission. Fixed changes in amino acid sequence, such as A82V in the EBOV glycoprotein (GP) that occurred early in the 2013–16 epidemic, are suspected to confer a selective advantage to the virus. We used biochemical assays of GP function to show that A82V, as well as a polymorphism in residue 544 identified in other outbreaks, enhances infection by decreasing the threshold for activation of membrane fusion activity triggered by the host factors cathepsin B and Niemann-Pick C1. Importantly, the increase in infectivity comes with the cost of decreased virus stability. Thus, emergence of a virus GP with altered properties that can affect transmission and virulence may have contributed to the severity and scope of the 2013–16 EBOV epidemic. [Display omitted] •A82V in the 2013 epidemic EBOV glycoprotein confers increased membrane fusion activity•A82V confers decreased virus dependence on host factors for infection•The increase in virus infectivity comes at a cost of decreased stability•An additional polymorphism from other outbreaks has the same properties as A82V A fixed A82V polymorphism in the EBOV glycoprotein that occurred early in the 2013–16 epidemic is suspected to confer a selective advantage. Wang et al. show that A82V and another polymorphism from other outbreaks confers increased EBOV infectivity and decreased host entry factor dependency, at the cost of decreased virus stability.