Smallpox inhibitor of complement enzymes (SPICE): Regulation of complement activation on cells and mechanism of its cellular attachment

M. Kathryn Liszewski, Paula Bertram, Marilyn K. Leung, Richard Hauhart, Lijuan Zhang, John P. Atkinson

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Despite eradication of smallpox three decades ago, public health concerns remain due to its potential use as a bioterrorist weapon. Smallpox and other orthopoxviruses express virulence factors that inhibit the host's complement system. In this study, our goals were to characterize the ability of the smallpox inhibitor of complement enzymes, SPICE, to regulate human complement on the cell surface. We demonstrate that SPICE binds to a variety of cell types and that the heparan sulfate and chondroitin sulfate glycosaminoglycans serve as attachment sites. A transmembrane-engineered version as well as soluble recombinant SPICE inhibited complement activation at the C3 convertase step with equal or greater efficiency than that of the related host regulators. Moreover, SPICE attached to glycosaminoglycans was more efficient than transmembrane SPICE. We also demonstrate that this virulence activity of SPICE on cells could be blocked by a mAb to SPICE. These results provide insights related to the complement inhibitory activities of poxviral inhibitors of complement and describe a mAb with therapeutic potential.

Original languageEnglish
Pages (from-to)4199-4207
Number of pages9
JournalJournal of Immunology
Volume181
Issue number6
DOIs
StatePublished - Sep 15 2008

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