title: Monoclonal antibody against the poly-gamma-D-glutamic acid capsule of Bacillus anthracis protects mice from enhanced lethal toxin activity due to capsule and anthrax spore challenge.
abstract: BACKGROUND
  The poly-gamma-D-glutamic acid (PGA) capsule, a major virulence factor of Bacillus anthracis, protects bacilli from immune surveillance and allows its unimpeded growth in the host. Recently, the importance of the PGA in the pathogenesis of anthrax infection has been reported. The PGA capsule is associated with lethal toxin (LT) in the blood of experimentally infected animals and enhances the cytotoxicity of LT.
  
  
  METHODS
  To investigate the role of anti-PGA Abs on progression of anthrax infection, two mouse anti-PGA mAbs with K(d) values of 0.8 microM and 2.6 microM respectively were produced and in silico three dimensional (3D) models of mAbs with their cognitive PGA antigen complex were analyzed.
  
  
  RESULTS
  Anti-PGA mAbs specifically bound encapsulated B. anthracis H9401 and showed opsonophagocytosis activity against the bacteria with complement. The enhancement effect of PGA on LT-mediated cytotoxicity was confirmed ex vivo using mouse bone marrow-derived macrophages and was effectively inhibited by anti-PGA mAb. Passive immunization of mAb completely protected mice from PGA-enhanced LT toxicity and partially rescued mice from anthrax spore challenges. 3D structure models of these mAbs and PGA complex support specific interactions between CDR and cognitive PGA. These results indicate that mouse mAb against PGA capsule prevents the progress of anthrax disease not only by eliminating the vegetative form of encapsulated B. anthracis but also by inhibiting the enhanced cytotoxic activity of LT by PGA through specific binding with PGA capsule antigen.
  
  
  CONCLUSIONS
  Our results suggest a potential role for PGA antibodies in preventing and treating anthrax infection.
authors.affiliation: Division of High-Risk Pathogen Research, Center for Infectious Diseases, National Institute of Health, 187 Osongsaengmyeong2-ro, Cheongwon-gun, Chungbuk 363-951, Republic of Korea.
authors.forename: Jeyoun
authors.initials: J
authors.lastname: Jang
authors.forename: Minhui
authors.initials: M
authors.lastname: Cho
authors.forename: Hae-Ri
authors.initials: HR
authors.lastname: Lee
authors.forename: Kiweon
authors.initials: K
authors.lastname: Cha
authors.forename: Jeong-Hoon
authors.initials: JH
authors.lastname: Chun
authors.forename: Kee-Jong
authors.initials: KJ
authors.lastname: Hong
authors.forename: Jungchan
authors.initials: J
authors.lastname: Park
authors.forename: Gi-Eun
authors.initials: GE
authors.lastname: Rhie
mesh_terms: D000818:Animals; D000881:Anthrax / Q000276:immunology / Q000382:microbiology / Q000401:mortality / Q000517:prevention & control*; D022122:Anthrax Vaccines / Q000008:administration & dosage*; D000907:Antibodies, Bacterial / Q000008:administration & dosage* / Q000096:biosynthesis; D000911:Antibodies, Monoclonal / Q000008:administration & dosage* / Q000096:biosynthesis; D000942:Antigens, Bacterial / Q000276:immunology*; D001408:Bacillus anthracis / Q000187:drug effects / Q000276:immunology / Q000472:pathogenicity; D016667:Bacterial Capsules / Q000276:immunology*; D001427:Bacterial Toxins / Q000276:immunology; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D007116:Immunization, Passive; D007700:Kinetics; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D051379:Mice; D008807:Mice, Inbred BALB C; D062105:Molecular Docking Simulation; D011099:Polyglutamic Acid / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000276:immunology; D013171:Spores, Bacterial / Q000187:drug effects / Q000276:immunology / Q000472:pathogenicity; D016019:Survival Analysis; D037521:Virulence Factors / Q000037:antagonists & inhibitors / Q000276:immunology
chemical_list: D022122:Anthrax Vaccines; D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D037521:Virulence Factors; C030325:anthrax toxin; C511775:poly(gamma-glutamic acid); D011099:Polyglutamic Acid