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Streptococcus agalactiae CAMP factor/protein B does not bind to human IgG


CAMP factor is an extracellular cytolytic protein produced by Streptococcus agalactiae. CAMP factor has been reported to bind the Fc fragments of immunoglobulin G (IgG) and has therefore also been called protein B, in analogy to protein A of Staphylococcus aureus. We attempted to characterize the interaction of protein B with IgG in more detail. In contrast to protein A, CAMP factor does not inhibit the activation of complement by hemolysin antibodies bound to sheep red cell surfaces. IgG also failed to inhibit the co-hemolytic activity of CAMP factor, which is in disagreement with previous findings. After co-incubation, CAMP factor and IgG were cleanly separated by gel filtration, indicating that no binding had occurred.

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Correspondence to Michael Palmer.

Additional information

Waseem El-Huneidi and Ryan Mui contributed equally to this work.

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El-Huneidi, W., Mui, R., Zhang, T.H. et al. Streptococcus agalactiae CAMP factor/protein B does not bind to human IgG. Med Microbiol Immunol 196, 73–77 (2007).

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  • CAMP factor
  • Protein B
  • Streptococcus agalactiae
  • Immunoglobulin G
  • Antibody-binding proteins