Macaque Monoclonal Antibodies Targeting Novel Conserved Epitopes within Filovirus Glycoprotein

Abstract

Filoviruses cause highly lethal viral hemorrhagic fever in humans and nonhuman primates. Current immunotherapeutic options for filoviruses are mostly specific to Ebola virus (EBOV), although other members of Filoviridae such as Sudan virus (SUDV), Bundibugyo virus (BDBV), and Marburg virus (MARV) have also caused sizeable human outbreaks. Here we report a set of pan-ebolavirus and pan-filovirus monoclonal antibodies (MAbs) derived from cynomolgus macaques immunized repeatedly with a mixture of engineered glycoproteins (GPs) and virus-like particles (VLPs) for three different filovirus species. The antibodies recognize novel neutralizing and nonneutralizing epitopes on the filovirus glycoprotein, including conserved conformational epitopes within the core regions of the GP1 subunit and a novel linear epitope within the glycan cap. We further report the first filovirus antibody binding to a highly conserved epitope within the fusion loop of ebolavirus and marburgvirus species. One of the antibodies binding to the core GP1 region of all ebolavirus species and with lower affinity to MARV GP cross neutralized both SUDV and EBOV, the most divergent ebolavirus species. In a mouse model of EBOV infection, this antibody provided 100% protection when administered in two doses and partial, but significant, protection when given once at the peak of viremia 3 days postinfection. Furthermore, we describe novel cocktails of antibodies with enhanced protective efficacy compared to individual MAbs. In summary, the present work describes multiple novel, cross-reactive filovirus epitopes and innovative combination concepts that challenge the current therapeutic models. IMPORTANCEFiloviruses are among the most deadly human pathogens. The 2014-2015 outbreak of Ebola virus disease (EVD) led to more than 27,000 cases and 11,000 fatalities. While there are five species of Ebolavirus and several strains of marburgvirus, the current immunotherapeutics primarily target Ebola virus. Since the nature of future outbreaks cannot be predicted, there is an urgent need for therapeutics with broad protective efficacy against multiple filoviruses. Here we describe a set of monoclonal antibodies cross-reactive with multiple filovirus species. These antibodies target novel conserved epitopes within the envelope glycoprotein and exhibit protective efficacy in mice. We further present novel concepts for combination of cross-reactive antibodies against multiple epitopes that show enhanced efficacy compared to monotherapy and provide complete protection in mice. These findings set the stage for further evaluation of these antibodies in nonhuman primates and development of effective pan-filovirus immunotherapeutics for use in future outbreaks. F iloviruses consisting of Marburg virus (MARV), Ravn virus (RAVV), and five species of ebolavirus, Ebola virus (EBOV), Sudan virus (SUDV), Bundibugyo virus (BDBV), Reston virus (RESTV), and Taï Forest virus (TAFV), are causative agents of severe hemorrhagic fever in humans and nonhuman primates (NHPs) (1, ...

Monoclonal antibodies for the treatment of Ebola virus disease

“…In a mouse model of EBOV infection, FVM04 was fully protective when used in two doses (2 h and 3 days postchallenge). When given a single dose 3 days postchallenge, survival rate was 40% [53].…”

“…Therefore, broadly protective treatment options are needed. Multiple mAbs have been generated, that elicit cross-reactivity in vitro and efficacy in mouse models for different Ebola virus species [49,50] including Marburg virus [51][52][53]. Furuyama et al generated mAb 6D6, which was found to efficiently neutralize the infectivity of vesicular stomatitis virus (VSV) pseudo-typed with GPs of all known Ebola viruses (EBOV, SUDV, TAFV, BDBV, and RESTV), but not Marburg virus (MARV).…”

Development and Characterization of Neutralizing Antibodies Against Zaire Ebolavirus Glycoprotein and Protein 40

“…However, limited but promising therapeutic evidence is available in humans [5,32]. Up to now, over 500 mAbs against EBOV have been extracted from recovered patients [15,17,33,34] or developed from animal models [35,36]; however, most of those mAbs have not been checked in clinical trials. To date, about 20 kinds of EBOV mAbs have been identified and characterized, several of them were found promising in non-human primate models, such as mAb114, MIL77E, MB-003, ZMab, and ZMapp TM [5,6].…”

Neglected filoviruses

“…A handful of BDBV-specific monoclonal or polyclonal murine, rabbit or crab-eating macaque antibodies (Ou et al 2011;Holtsberg et al 2015;Keck et al 2015;Wang et al 2015), BDBV …”

“…Several serological or nucleic-acid based RESTVspecific diagnostic systems have been described (Kalter et al 1995;Ksiazek et al 1999;Niikura et al 2001;Ikegami et al 2002bIkegami et al , 2003aOu et al 2011). RESTV-specific monoclonal or polyclonal murine, rabbit or crab-eating macaque antibodies (Ou et al 2011;Holtsberg et al 2015;Keck et al 2015;Wang et al 2015), RESTV cross-reactive murine antibodies (Fusco et al 2015;Wang et al 2015;Furuyama et al 2016), RESTV cross-reactive murine scFvs and IgNAR Vs raised against inactivated EBOV particles (Goodchild et al 2011) are available.…”