BROADLY NEUTRALIZING ANTIBODIES FROM HUMAN SURVIVORS TARGET A CONSERVED SITE IN THE EBOLA VIRUS GLYCOPROTEIN HR2/MPER REGION

Ebola virus (EBOV) in humans causes a severe illness with high mortality rates. Several strategies have been developed in the past to treat EBOV infection, including the antibody cocktail ZMapp(TM) that has been shown to be effective in nonhuman primate models of infection(1) and has been used under compassionate-treatment protocols in humans(2). ZMapp(TM) is a mixture of three chimerized murine monoclonal antibodies (mAbs)(3–6) that target EBOV-specific epitopes on the surface glycoprotein (GP)(7,8). However, ZMapp(TM) mAbs do not neutralize other species from the Ebolavirus genus, such as Bundibugyo virus (BDBV), Reston virus (RESTV) or Sudan virus (SUDV). Here we describe three naturally-occurring human cross-neutralizing mAbs, from BDBV survivors, that target an antigenic site in the canonical heptad repeat 2 (HR2) region near the membrane proximal external region (MPER) of GP. The identification of a conserved neutralizing antigenic site in the GP suggests that these mAbs could be used to design universal antibody therapeutics against diverse ebolavirus species. Furthermore, we found that immunization with a peptide comprising the HR2/MPER antigenic site elicits neutralizing antibodies in rabbits. Structural features determined by conserved residues in the antigenic site described here could inform an epitope-based vaccine design against infection caused by diverse ebolavirus species.