Glycosylation-dependent opsonophagocytic activity of staphylococcal protein A antibodies

Journal Article · Thu Aug 27 00:00:00 EDT 2020 · Proceedings of the National Academy of Sciences of the United States of America

DOI:https://doi.org/10.1073/pnas.2003621117· OSTI ID:1815835

Chen, Xinhai ^[1]; Shi, Miaomiao ^[2]; Tong, Xin ^[3]; Kim, Hwan Keun ^[2]; Wang, Lai-Xi ^[3]; Schneewind, Olaf ^[2]; Missiakas, Dominique ^[2]

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1. Argonne National Lab. (ANL), Argonne, IL (United States). Howard Taylor Ricketts Lab.; Univ. of Chicago, IL (United States). Dept. of Microbiology; OSTI
2. Argonne National Lab. (ANL), Argonne, IL (United States). Howard Taylor Ricketts Lab.; Univ. of Chicago, IL (United States). Dept. of Microbiology
3. Univ. of Maryland, College Park, MD (United States). Dept. of Chemistry and Biochemistry

Antibodies may bind to bacterial pathogens or their toxins to control infections, and their effector activity is mediated through the recruitment of complement component C1q or the engagement with Fcγ receptors (FcγRs). For bacterial pathogens that rely on a single toxin to cause disease, immunity correlates with toxin neutralization. Most other bacterial pathogens, includingStaphylococcus aureus, secrete numerous toxins and evolved multiple mechanisms to escape opsonization and complement killing. Several vaccine candidates targeting defined surface antigens ofS. aureushave failed to meet clinical endpoints. It is unclear that such failures can be solely attributed to the poor selection of antibody targets. Thus far, studies to delineate antibody-mediated uptake and killing of Gram-positive pathogens remain extremely limited. Here, we exploit 3F6-hIgG1, a human monoclonal antibody that binds and neutralizes the abundant surface-exposed Staphylococcal protein A (SpA). We find that galactosylation of 3F6-hIgG1 that favors C1q recruitment is indispensable for opsonophagocytic killing of staphylococci and for protection against bloodstream infection in animals. However, the simple removal of fucosyl residues, which results in reduced C1q binding and increased engagement with FcγR, maintains the opsonophagocytic killing and protective attributes of the antibody. We confirm these results by engineering 3F6-hIgG1 variants with biased binding toward C1q or FcγRs. While the therapeutic benefit of monoclonal antibodies against infectious disease agents may be debatable, the functional characterization of such antibodies represents a powerful tool for the development of correlates of protection that may guide future vaccine trials.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: AC02-06CH11357
• OSTI ID: 1815835
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 37 Vol. 117; ISSN 0027-8424
• Publisher: National Academy of Sciences
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
C1q
FcγR
Staphylococcal protein A
glycosylation
monoclonal antibody