Enhanced potency of a fucose-free monoclonal antibody being developed as an Ebola virus immunoprotectant

Proc Natl Acad Sci U S A. 2011 Dec 20;108(51):20690-4. doi: 10.1073/pnas.1108360108. Epub 2011 Dec 5.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / chemistry
  • Antiviral Agents / chemistry
  • Complement C1q / chemistry
  • Ebolavirus / immunology
  • Ebolavirus / metabolism*
  • Female
  • Fucose / chemistry
  • Fucose / immunology*
  • Glycosylation
  • Hemorrhagic Fever, Ebola / immunology
  • Hemorrhagic Fever, Ebola / prevention & control
  • Humans
  • Immune System
  • Immunization, Passive
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C57BL
  • Molecular Sequence Data
  • Surface Plasmon Resonance
  • Tobacco

Substances

  • Antibodies, Monoclonal
  • Antiviral Agents
  • Fucose
  • Complement C1q

Associated data

  • GENBANK/JN374688
  • GENBANK/JN374689