title: IgG subclass and heavy chain domains contribute to binding and protection by mAbs to the poly γ-D-glutamic acid capsular antigen of Bacillus anthracis.
abstract: Bacterial capsules are common targets for antibody-mediated immunity. The capsule of Bacillus anthracis is unusual among capsules because it is composed of a polymer of poly-γ-d-glutamic acid (γdPGA). We previously generated murine IgG3 monoclonal antibodies (mAbs) to γdPGA that were protective in a murine model of pulmonary anthrax. IgG3 antibodies are characteristic of the murine response to polysaccharide antigens. The goal of the present study was to produce subclass switch variants of the γdPGA mAbs (IgG3 → IgG1 → IgG2b → IgG2a) and assess the contribution of subclass to antibody affinity and protection. Subclass switch antibodies had identical variable regions but differed in their heavy chains. The results showed that a switch from the protective IgG3 to IgG1, IgG2b or IgG2a was accompanied by i) a loss of protective activity ii) a change in mAb binding to the capsular matrix, and iii) a loss of affinity. These results identify a role for the heavy chain constant region in mAb binding. Hybrid mAbs were constructed in which the CH1, CH2 or CH3 heavy chain constant domains from a non-protective, low binding IgG2b mAb were swapped into the protective IgG3 mAb. The IgG3 mAb that contained the CH1 domain from IgG2b showed no loss of affinity or protection. In contrast, swapping the CH2 or CH3 domains from IgG2b into IgG3 produced a reduction in affinity and a loss of protection. These studies identify a role for the constant region of IgG heavy chains in affinity and protection against an encapsulated bacterial pathogen.
authors: Department of Microbiology and Immunology, University of Nevada School of Medicine, Reno, Nevada, United States of America.
authors: Maria
authors: M
authors: Hovenden
authors: Mark A
authors: MA
authors: Hubbard
authors: David P
authors: DP
authors: Aucoin
authors: Peter
authors: P
authors: Thorkildson
authors: Dana E
authors: DE
authors: Reed
authors: William H
authors: WH
authors: Welch
authors: C Rick
authors: CR
authors: Lyons
authors: Julie A
authors: JA
authors: Lovchik
authors: Thomas R
authors: TR
authors: Kozel
mesh_terms: D000818:Animals; D000881:Anthrax / Q000276:immunology* / Q000382:microbiology; D000911:Antibodies, Monoclonal / Q000276:immunology; D000915:Antibody Affinity; D000937:Antigen-Antibody Reactions; D001408:Bacillus anthracis / Q000276:immunology*; D016667:Bacterial Capsules / Q000276:immunology; D018698:Glutamic Acid / Q000276:immunology; D017578:Immunoglobulin Class Switching; D007127:Immunoglobulin Constant Regions / Q000276:immunology*; D007074:Immunoglobulin G / Q000737:chemistry / Q000276:immunology*; D007143:Immunoglobulin Heavy Chains / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D017434:Protein Structure, Tertiary
chemical_list: D000911:Antibodies, Monoclonal; D007127:Immunoglobulin Constant Regions; D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D018698:Glutamic Acid
references: Annu Rev Microbiol. 2001;55:647-71
references: 11544370
references: J Immunol. 1995 Feb 15;154(4):1810-6
references: 7836766
references: J Biol Chem. 2006 Feb 24;281(8):4831-43
references: 16293624
references: FEMS Immunol Med Microbiol. 2004 Apr 9;40(3):231-7
references: 15039099
references: Immunogenetics. 1984;20(5):577-81
references: 6437976
references: J Biol Chem. 2007 May 4;282(18):13917-27
references: 17353196
references: Trends Immunol. 2008 Feb;29(2):91-7
references: 18191616
references: Infect Immun. 1985 Aug;49(2):291-7
references: 3926644
references: Infect Immun. 1998 Mar;66(3):1057-62
references: 9488395
references: J Immunol. 1991 Apr 15;146(8):2659-63
references: 1901882
references: Proc Natl Acad Sci U S A. 2012 Jul 31;109(31):12272-3
references: 22826242
references: J Bacteriol. 1989 Feb;171(2):722-30
references: 2536679
references: J Gen Microbiol. 1961 Sep;26:49-63
references: 13916257
references: Vaccine. 2004 Nov 15;23(1):43-7
references: 15519706
references: Infect Immun. 2007 Jan;75(1):152-63
references: 17060470
references: J Bacteriol. 1962 Jun;83:1274-80
references: 13866126
references: J Infect Dis. 1993 Jan;167(1):221-6
references: 8418172
references: EMBO J. 1988 Jul;7(7):1989-94
references: 3138110
references: Proc Natl Acad Sci U S A. 2004 Apr 6;101(14):5042-7
references: 15051894
references: J Biol Chem. 1996 Jan 19;271(3):1527-33
references: 8576148
references: Diagn Clin Immunol. 1988;5(5):241-8
references: 3282712
references: Immunogenetics. 1984;20(5):565-75
references: 6209216
references: J Immunol. 2000 May 1;164(9):4835-42
references: 10779792
references: Genomics. 1997 Apr 1;41(1):100-4
references: 9126488
references: Blood. 2012 Jun 14;119(24):5640-9
references: 22535666
references: Appl Microbiol. 1963 Jul;11:330-4
references: 13972634
references: J Bacteriol. 1958 Nov;76(5):499-503
references: 13598708
references: Curr Top Microbiol Immunol. 2001;260:65-85
references: 11443882
references: Immunol Today. 1992 May;13(5):164-8
references: 1642754
references: J Biol Chem. 2012 Oct 12;287(42):35409-35417
references: 22930758
references: Proc Natl Acad Sci U S A. 2012 Jul 31;109(31):12680-5
references: 22723360
references: J Immunol. 1998 Jan 1;160(1):20-3
references: 9551950
references: Proc Natl Acad Sci U S A. 2003 Jul 22;100(15):8945-50
references: 12857944
references: Immunity. 2005 Jul;23(1):41-51
references: 16039578
references: Curr Top Microbiol Immunol. 1989;146:169-80
references: 2659266
references: J Immunol Methods. 1984 Nov 30;74(2):307-15
references: 6438240
references: Proc Natl Acad Sci U S A. 2011 Jan 11;108(2):739-44
references: 21187383
references: Contemp Top Mol Immunol. 1976;5:217-28
references: 63353
references: Biochem J. 1956 Jul;63(3):437-42
references: 13341899
references: Infect Immun. 2004 Sep;72(9):5460-3
references: 15322045
references: J Immunol. 1993 Mar 15;150(6):2231-42
references: 7680687
references: J Biol Chem. 1994 Apr 29;269(17):13048-55
references: 7909805
references: Proc Natl Acad Sci U S A. 2003 Sep 16;100(19):10925-30
references: 12960361
references: Immunology. 1967 Dec;13(6):577-83
references: 4965130
references: Infect Immun. 1983 Jan;39(1):371-6
references: 6401695
references: Springer Semin Immunopathol. 1993;15(2-3):275-91
references: 8256202
references: Eur J Immunol. 1981 Dec;11(12):1012-6
references: 7327198
references: Mol Immunol. 1994 Jun;31(8):577-84
references: 7515151
references: J Exp Med. 1980 Apr 1;151(4):853-62
references: 6966310
references: J Immunol. 1978 Aug;121(2):566-72
references: 79606
references: J Immunol. 2005 Feb 15;174(4):2132-42
references: 15699144