Animal and human antibodies to distinct Staphylococcus aureus antigens mutually neutralize opsonic killing and protection in mice
David Skurnik, … , Jean C. Lee, Gerald B. Pier
David Skurnik, … , Jean C. Lee, Gerald B. Pier
Published August 25, 2010
Citation Information: J Clin Invest. 2010;120(9):3220-3233. https://doi.org/10.1172/JCI42748.
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Research Article

Animal and human antibodies to distinct Staphylococcus aureus antigens mutually neutralize opsonic killing and protection in mice

Abstract

New prophylactic approaches are needed to control infection with the Gram-positive bacterium Staphylococcus aureus, which is a major cause of nosocomial and community-acquired infections. To develop these, greater understanding of protective immunity against S. aureus infection is needed. Human immunity to extracellular Gram-positive bacterial pathogens is primarily mediated by opsonic killing (OPK) via antibodies specific for surface polysaccharides. S. aureus expresses two such antigens, capsular polysaccharide (CP) and poly-N-acetyl glucosamine (PNAG). Here, we have shown that immunization-induced polyclonal animal antisera and monoclonal antibodies specific for either CP or PNAG antigens have excellent in vitro OPK activity in human blood but that when mixed together they show potent interference in OPK activity. In addition, reductions in antibody binding to the bacterial surface, complement deposition, and passive protection were seen in two mouse models of S. aureus infection. Electron microscopy, isothermal calorimetry, and surface plasmon resonance indicated that antibodies to CP and PNAG bound together via an apparent idiotype–anti-idiotype interaction. This interaction was also found in sera from humans with S. aureus bacteremia. These findings suggest that the lack of effective immunity to S. aureus infections in humans could be due, in part, to interference in OPK when antibodies to CP and PNAG antigens are both present. This information could be used to better design S. aureus vaccine components.

Authors

David Skurnik, Massimo Merighi, Martha Grout, Mihaela Gadjeva, Tomas Maira-Litran, Maria Ericsson, Donald A. Goldmann, Susan S. Huang, Rupak Datta, Jean C. Lee, Gerald B. Pier

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Figure 7

Isothermal calorimetry analysis of the binding of mAb to CP8 or PNAG with polyclonal rabbit antisera to PNAG, CP8, or CP5.

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Isothermal calorimetry analysis of the binding of mAb to CP8 or PNAG wit...
Background heat generated from the addition to MEM of rabbit antibody instead of the addition of mAbs to CP8 or PNAG (example in F) was subtracted. (A) Binding curve obtained when solutions containing 5 μM mouse mAb to CP8 was placed in the calorimetry sample cell (Cell) and 250 μg rabbit IgG from antisera raised to PNAG (anti-PNAG) was injected into the cell (Titrant). (B and C) Binding curves obtained when solutions containing 250 μg rabbit IgG raised to CP8 or CP5 (Titrant) were injected into the cell containing 5 μM mAb to PNAG. (D) No binding was observed when a solution containing 5 μM of mouse mAb to CP8 was placed in the cell and NRS (Titrant) was injected into the cell. (E) No binding was observed when a solution containing 5 μM of human mAb to PNAG was placed in the cell and NRS was injected into the cell. (F) Example of background heat generated by addition of rabbit antisera to CP8 or CP5 or PNAG into MEM. (G–I) Addition of rabbit antisera to CP8, CP5, or NRS as a control (Titrant) to the cell containing 5 μM of Fabs prepared from mAb F598 specific to PNAG.