A novel L-ficolin/mannose-binding lectin chimeric molecule with enhanced activity against Ebola virus

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  • Ian C Michelow, Denmark
  • Mingdong Dong
  • Bruce A Mungall, Denmark
  • L Michael Yantosca, Denmark
  • Calli Lear, Denmark
  • Xin Ji, Denmark
  • Marshall Karpel, Denmark
  • Christina L Rootes, Denmark
  • Matthew Brudner, Denmark
  • Gunnar Houen, Denmark
  • Damon P Eisen, Denmark
  • T Bernard Kinane, Denmark
  • Kazue Takahashi, Denmark
  • Gregory L Stahl, Denmark
  • Gene G Olinger, Denmark
  • Gregory T Spear, Denmark
  • R Alan B Ezekowitz, Denmark
  • Emmett V Schmidt, Denmark
  • Interdisciplinary Nanoscience Center
Ebola viruses constitute a newly emerging public threat because they cause rapidly fatal hemorrhagic fevers for which no treatment exists and they can be manipulated as bioweapons. We targeted conserved N-glycosylated carbohydrate ligands on viral envelope surfaces using novel immune therapies. Mannose-binding lectin (MBL) and L-ficolin (L-FCN) were selected because they function as opsonins and activate complement. Given that MBL has a complex quaternary structure unsuitable for large-scale cost-effective production, we sought to develop a less complex chimeric fusion protein with similar ligand recognition and enhanced effector functions. We tested recombinant human MBL and three L-FCN/MBL variants that contained the MBL carbohydrate recognition domain and varying lengths of the L-FCN collagenous domain. Non-reduced chimeric proteins formed predominantly nona- and dodecameric oligomers whereas rhMBL formed octadecameric and larger oligomers. Surface plasmon resonance revealed that L-FCN/MBL76 had the highest binding affinities for N-acetylglucosamine-BSA and mannan. The same chimeric protein displayed superior complement C4 cleavage and binding to calreticulin (cC1qR), a putative receptor for MBL. L-FCN/MBL76 reduced infection by wild type Ebola Zaire virus significantly greater than the other molecules. Tapping-mode atomic force microscopy revealed that L-FCN/MBL76 was significantly less tall than the other molecules despite similar polypeptide lengths. We propose that alterations in the quaternary structure of L-FCN/MBL76 resulted in greater flexibility in the collagenous or neck regions. Similarly, a more pliable molecule might enhance cooperativity between the carbohydrate recognition domains and their cognate ligands, complement activation and calreticulin binding dynamics. L-FCN/MBL chimeric proteins should be considered as potential novel therapeutics.
Original languageEnglish
JournalJournal of Biological Chemistry
Publication statusPublished - 2010

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