More than meets the Kappa for Antibody Superantigen Protein L (PpL)

Immunoglobulin superantigens play an important role in the affinity purification of antibodies and underlie the microbiota-immune axis at mucosal areas Focussing on the Staphylococcal Protein A (SpA), Streptococcal Protein G (SpG), and the Finegoldia Protein L (PpL) that were previously thought to bind to only specific regions of human antibodies, a systematic and holistic analysis of the antibody regions using 63 antibody permutations involving six Vκ and seven VH region IgG1 revealed showed novel PpL-antibody interactions. While SpA and SpG showed relatively consistent interactions with the antibodies, our findings showed PpL binding to certain VH-Vκ2, 5 and 6 interactions had contribution by other antibody regions. The findings of this have implications on PpL-based affinity antibody purifications and antibody design as well as provides novel insights to PpL-based microbiota-immune axis effects.

Production of Antibodies in Egg Whites of Chickens

Background: IgM, which participates in the primary immune response, is the primary antibody in egg whites. There is scant information about the production of antibodies in egg whites. This study describes the preparation of antibodies against a bacterial antigen, staphylococcal protein-A. Methods: The detection of antibodies against staphylococcal protein-A in egg white was performed by ELISA, and the antibodies were purified by protein-A affinity chromatography. Agglutination inhibition of Staphylococcus aureus Cowan I strains by purified antibodies against protein-A in vitro was investigated. Results: ELISA showed the production of antibodies against staphylococcal protein-A in the egg whites of layer hens. The antibodies were separated using affinity chromatography. The agglutination of Staphylococcus aureus Cowan I strains occurred when the purified antibodies were incubated with S. aureus. Conclusion: The results showed that it is possible to produce antibodies against bacterial antigens in egg whites, which can have industrial applications in the preparation of antibodies for immunotherapy of infectious diseases.

Staphylococcal Protein A Induces Leukocyte Necrosis by Complexing with Human Immunoglobulins

Staphylococcus aureus is one of the largest health care threats faced by humankind, with a reported mortality rate within the United States greater than that of HIV/AIDS, tuberculosis, and viral hepatitis combined. One of the defining features of S. aureus as a human pathogen is its ability to evade and impair the human immune response through expression of staphylococcal protein A.

Diversity of Functionally Distinct Clonal Sets of Human Conventional Memory B Cells That Bind Staphylococcal Protein A

Staphylococcus aureus, a common cause of serious and often fatal infections, is well-armed with secreted factors that disarm host immune defenses. Highly expressed in vivo during infection, Staphylococcal protein A (SpA) is reported to also contribute to nasal colonization that can be a prelude to invasive infection. Co-evolution with the host immune system has provided SpA with an Fc-antibody binding site, and a Fab-binding site responsible for non-immune superantigen interactions via germline-encoded surfaces expressed on many human BCRs. We wondered whether the recurrent exposures to S. aureus commonly experienced by adults, result in the accumulation of memory B-cell responses to other determinants on SpA. We therefore isolated SpA-specific class-switched memory B cells, and characterized their encoding VH : VL antibody genes. In SpA-reactive memory B cells, we confirmed a striking bias in usage for VH genes, which retain the surface that mediates the SpA-superantigen interaction. We postulate these interactions reflect co-evolution of the host immune system and SpA, which during infection results in immune recruitment of an extraordinarily high prevalence of B cells in the repertoire that subverts the augmentation of protective defenses. Herein, we provide the first evidence that human memory responses are supplemented by B-cell clones, and circulating-antibodies, that bind to SpA determinants independent of the non-immune Fc- and Fab-binding sites. In parallel, we demonstrate that healthy individuals, and patients recovering from S. aureus infection, both have circulating antibodies with these conventional binding specificities. These findings rationalize the potential utility of incorporating specially engineered SpA proteins into a protective vaccine.