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

Larry Zeitlin, James Pettitt, Corinne Scully, Natasha Bohorova, Do Kim, Michael Pauly, Andrew Hiatt, Long Ngo, Herta Steinkellner, Kevin J. Whaley, Gene G. Olinger

Research output: Contribution to journalArticlepeer-review

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 (ED50 = 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.

Original languageEnglish (US)
Pages (from-to)20690-20694
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume108
Issue number51
DOIs
StatePublished - Dec 20 2011
Externally publishedYes

Keywords

  • Antibody glycosylation
  • Antibody-dependent cellular cytotoxicity
  • Antiviral
  • Passive immunization

ASJC Scopus subject areas

  • General

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