Complement alone drives efficacy of a chimeric antigonococcal monoclonal antibody
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Multidrug-resistant Neisseria gonorrhoeae is a global health problem. Monoclonal antibody (mAb) 2C7 recognizes a gonococcal lipooligosaccharide epitope that is expressed by >95% of clinical isolates and hastens gonococcal vaginal clearance in mice. Chimeric mAb 2C7 (human immunoglobulin G1 [IgG1]) with an E430G Fc modification that enhances Fc:Fc interactions and hexamerization following surface-target binding and increases complement activation (HexaBody technology) showed significantly greater C1q engagement and C4 and C3 deposition compared to mAb 2C7 with wild-type Fc. Greater complement activation by 2C7-E430G Fc translated to increased bactericidal activity in vitro and, consequently, enhanced efficacy in mice, compared with "Fc-unmodified" chimeric 2C7. Gonococci bind the complement inhibitors factor H (FH) and C4b-binding protein (C4BP) in a human-specific manner, which dampens antibody (Ab)-mediated complement-dependent killing. The variant 2C7-E430G Fc overcame the barrier posed by these inhibitors in human FH/C4BP transgenic mice, for which a single 1 μg intravenous dose cleared established infection. Chlamydia frequently coexists with and exacerbates gonorrhea; 2C7-E430G Fc also proved effective against gonorrhea in gonorrhea/chlamydia-coinfected mice. Complement activation alone was necessary and sufficient for 2C7 function, evidenced by the fact that (1) "complement-inactive" Fc modifications that engaged Fc gamma receptor (FcγR) rendered 2C7 ineffective, nonetheless; (2) 2C7 was nonfunctional in C1q-/- mice, when C5 function was blocked, or in C9-/- mice; and (3) 2C7 remained effective in neutrophil-depleted mice and in mice treated with PMX205, a C5a receptor (C5aR1) inhibitor. We highlight the importance of complement activation for antigonococcal Ab function in the genital tract. Elucidating the correlates of protection against gonorrhea will inform the development of Ab-based gonococcal vaccines and immunotherapeutics.
Date Issued
2019-06
Date Acceptance
2019-05-30
Citation
PLoS Biology, 2019, 17 (6)
ISSN
1544-9173
Publisher
Public Library of Science (PLoS)
Journal / Book Title
PLoS Biology
Volume
17
Issue
6
Copyright Statement
© 2019 Gulati et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/31216278
PII: PBIOLOGY-D-19-00436
Subjects
Developmental Biology
06 Biological Sciences
11 Medical and Health Sciences
07 Agricultural and Veterinary Sciences
Publication Status
Published
Coverage Spatial
United States
Article Number
e3000323