title: Enhanced potency of a fucose-free monoclonal antibody being developed as an Ebola virus immunoprotectant.
abstract: No countermeasures currently exist for the prevention or treatment of the severe sequelae of Filovirus (such as Ebola virus; EBOV) infection. To overcome this limitation in our biodefense preparedness, we have designed monoclonal antibodies (mAbs) which could be used in humans as immunoprotectants for EBOV, starting with a murine mAb (13F6) that recognizes the heavily glycosylated mucin-like domain of the virion-attached glycoprotein (GP). Point mutations were introduced into the variable region of the murine mAb to remove predicted human T-cell epitopes, and the variable regions joined to human constant regions to generate a mAb (h-13F6) appropriate for development for human use. We have evaluated the efficacy of three variants of h-13F6 carrying different glycosylation patterns in a lethal mouse EBOV challenge model. The pattern of glycosylation of the various mAbs was found to correlate to level of protection, with aglycosylated h-13F6 providing the least potent efficacy (ED(50) = 33 μg). A version with typical heterogenous mammalian glycoforms (ED(50) = 11 μg) had similar potency to the original murine mAb. However, h-13F6 carrying complex N-glycosylation lacking core fucose exhibited superior potency (ED(50) = 3 μg). Binding studies using Fcγ receptors revealed enhanced binding of nonfucosylated h-13F6 to mouse and human FcγRIII. Together the results indicate the presence of Fc N-glycans enhances the protective efficacy of h-13F6, and that mAbs manufactured with uniform glycosylation and a higher potency glycoform offer promise as biodefense therapeutics.
authors.affiliation: Mapp Biopharmaceutical, San Diego, CA 92121, USA. larry.zeitlin@mappbio.com
authors.forename: Larry
authors.initials: L
authors.lastname: Zeitlin
authors.forename: James
authors.initials: J
authors.lastname: Pettitt
authors.forename: Corinne
authors.initials: C
authors.lastname: Scully
authors.forename: Natasha
authors.initials: N
authors.lastname: Bohorova
authors.forename: Do
authors.initials: D
authors.lastname: Kim
authors.forename: Michael
authors.initials: M
authors.lastname: Pauly
authors.forename: Andrew
authors.initials: A
authors.lastname: Hiatt
authors.forename: Long
authors.initials: L
authors.lastname: Ngo
authors.forename: Herta
authors.initials: H
authors.lastname: Steinkellner
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Whaley
authors.forename: Gene G
authors.initials: GG
authors.lastname: Olinger
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D000998:Antiviral Agents / Q000737:chemistry; D015922:Complement C1q / Q000737:chemistry; D029043:Ebolavirus / Q000276:immunology / Q000378:metabolism*; D005260:Female; D005643:Fucose / Q000737:chemistry / Q000276:immunology*; D006031:Glycosylation; D019142:Hemorrhagic Fever, Ebola / Q000276:immunology / Q000517:prevention & control; D006801:Humans; D007107:Immune System; D007116:Immunization, Passive; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D020349:Surface Plasmon Resonance; D014026:Nicotiana
chemical_list: D000911:Antibodies, Monoclonal; D000998:Antiviral Agents; D005643:Fucose; D015922:Complement C1q