title: Novel Solutions for Vaccines and Diagnostics To Combat Brucellosis.
abstract: Brucellosis is diagnosed by detection of antibodies in the blood of animals and humans that are specific for two carbohydrate antigens, termed A and M, which are present concurrently in a single cell wall O-polysaccharide. Animal brucellosis vaccines contain these antigenic determinants, and consequently infected and vaccinated animals cannot be differentiated as both groups produce A and M specific antibodies. We hypothesized that chemical synthesis of a pure A vaccine would offer unique identification of infected animals by a synthetic M diagnostic antigen that would not react with antibodies generated by this vaccine. Two forms of the A antigen, a hexasaccharide and a heptasaccharide conjugated to tetanus toxoid via reducing and nonreducing terminal sugars, were synthesized and used as lead vaccine candidates. Mouse antibody profiles to these immunogens showed that to avoid reaction with diagnostic M antigen it was essential to maximize the induction of anti-A antibodies that bind internal oligosaccharide sequences and minimize production of antibodies directed toward the terminal nonreducing monosaccharide. This objective was achieved by conjugation ofBrucellaO-polysaccharide to tetanus toxoid via its periodate oxidized terminal nonreducing monosaccharide, thereby destroying terminal epitopes and focusing the antibody response on internal A epitopes. This establishes the method to resolve the decades-long challenge of how to create effective brucellosis vaccines without compromising diagnosis of infected animals.
authors.affiliation: Department of Chemistry, University of Alberta , Edmonton, Alberta T6G 2G2, Canada.
authors.forename: Satadru Sekhar
authors.initials: SS
authors.lastname: Mandal
authors.affiliation: Department of Bacteriology, Animal & Plant Health Agency, OIE Brucellosis Reference Laboratory, FAO/WHO Collaborating Centre for Brucellosis , Woodham Lane, Addlestone, Surrey, United Kingdom , KT15 3NB.
authors.forename: Lucy
authors.initials: L
authors.lastname: Duncombe
authors.affiliation: Department of Chemistry, University of Alberta , Edmonton, Alberta T6G 2G2, Canada.
authors.forename: N Vijaya
authors.initials: NV
authors.lastname: Ganesh
authors.affiliation: Department of Chemistry, University of Alberta , Edmonton, Alberta T6G 2G2, Canada.
authors.forename: Susmita
authors.initials: S
authors.lastname: Sarkar
authors.affiliation: Department of Bacteriology, Animal & Plant Health Agency, OIE Brucellosis Reference Laboratory, FAO/WHO Collaborating Centre for Brucellosis , Woodham Lane, Addlestone, Surrey, United Kingdom , KT15 3NB.
authors.forename: Laurence
authors.initials: L
authors.lastname: Howells
authors.affiliation: Vaccine Immunology Team, Department of Bacteriology, Animal & Plant Health Agency , Woodham Lane, Addlestone, Surrey, United Kingdom , KT15 3NB.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Hogarth
authors.affiliation: Department of Chemistry, University of Alberta , Edmonton, Alberta T6G 2G2, Canada.
authors.forename: David R
authors.initials: DR
authors.lastname: Bundle
authors.affiliation: Department of Bacteriology, Animal & Plant Health Agency, OIE Brucellosis Reference Laboratory, FAO/WHO Collaborating Centre for Brucellosis , Woodham Lane, Addlestone, Surrey, United Kingdom , KT15 3NB.
authors.forename: John
authors.initials: J
authors.lastname: McGiven