title: Murine antibody responses to the verotoxin 1 B subunit: demonstration of major histocompatibility complex dependence and an immunodominant epitope involving phenylalanine 30.
abstract: Structurally conserved verotoxin 1 (VT1) mutant derivatives, showing reduced receptor binding and cytotoxicity, may serve as natural toxoids to protect against VT-mediated disease. In this study, the antibody responses to the wild-type VT1 B subunit, a B-subunit mutant (Phe30Ala B), and the corresponding holotoxin (Phe30Ala HT) were examined in three inbred mouse strains. BALB/c (H-2d) and CBA (H-2k) mice produced strong antibody responses to both wild-type and mutant B subunits. VT1 B-raised sera reacted more strongly with VT1 B than with Phe30Ala B in enzyme-linked immunosorbent assays, while Phe30Ala B-raised sera reacted equally with VT1 B and Phe30Ala B. C57BL/6 (H-2b) and congenic BALB/c (BALB x B [H-2b]) mice produced no detectable antibody response to either VT1 B or Phe30Ala B. However, an anti-VT1 B antibody response was detected in H-2b mice immunized with biologically active Phe30Ala HT. Based on these observations, we conclude that the VT1 B subunit possesses a B-cell immunodominant epitope formed partly by phenylalanine 30 and that the B-subunit antibody response is dependent on the H-2 haplotype of the mouse strain. Our results also support a potential role for the A subunit in providing the T-cell help necessary to overcome a deficient B-subunit antibody response in H-2b mice.
authors.affiliation: Samuel Lunenfeld Research Institute, Mount Sinai Hospital, and Department of Microbiology, University of Toronto, Ontario, Canada.
authors.forename: D J
authors.initials: DJ
authors.lastname: Bast
authors.forename: J
authors.initials: J
authors.lastname: Sandhu
authors.forename: N
authors.initials: N
authors.lastname: Hozumi
authors.forename: B
authors.initials: B
authors.lastname: Barber
authors.forename: J
authors.initials: J
authors.lastname: Brunton
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology; D001427:Bacterial Toxins / Q000276:immunology*; D003603:Cytotoxins / Q000276:immunology*; D000939:Epitopes / Q000276:immunology*; D004926:Escherichia coli; D005260:Female; D008285:Major Histocompatibility Complex / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008808:Mice, Inbred CBA; D010649:Phenylalanine / Q000032:analysis; D022622:Shiga Toxin 1; D013045:Species Specificity
chemical_list: D001427:Bacterial Toxins; D003603:Cytotoxins; D000939:Epitopes; D022622:Shiga Toxin 1; D010649:Phenylalanine