title: Passive immunization with a polyclonal antiserum to the hemoglobin receptor of Haemophilus ducreyi confers protection against a homologous challenge in the experimental swine model of chancroid.
abstract: Haemophilus ducreyi, the etiologic agent of chancroid, has an obligate requirement for heme. Heme is acquired by H. ducreyi from its human host via TonB-dependent transporters expressed at its bacterial surface. Of 3 TonB-dependent transporters encoded in the genome of H. ducreyi, only the hemoglobin receptor, HgbA, is required to establish infection during the early stages of the experimental human model of chancroid. Active immunization with a native preparation of HgbA (nHgbA) confers complete protection in the experimental swine model of chancroid, using either Freund's or monophosphoryl lipid A as adjuvants. To determine if transfer of anti-nHgbA serum is sufficient to confer protection, a passive immunization experiment using pooled nHgbA antiserum was conducted in the experimental swine model of chancroid. Pigs receiving this pooled nHgbA antiserum were protected from a homologous, but not a heterologous, challenge. Passively transferred polyclonal antibodies elicited to nHgbA bound the surface of H. ducreyi and partially blocked hemoglobin binding by nHgbA, but were not bactericidal. Taken together, these data suggest that the humoral immune response to the HgbA vaccine is protective against an H. ducreyi infection, possibly by preventing acquisition of the essential nutrient heme.
authors.affiliation: Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA. isabelle_leduc@med.unc.edu
authors.forename: Isabelle
authors.initials: I
authors.lastname: Leduc
authors.forename: William G
authors.initials: WG
authors.lastname: Fusco
authors.forename: Neelima
authors.initials: N
authors.lastname: Choudhary
authors.forename: Patty A
authors.initials: PA
authors.lastname: Routh
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Cholon
authors.forename: Marcia M
authors.initials: MM
authors.lastname: Hobbs
authors.forename: Glen W
authors.initials: GW
authors.lastname: Almond
authors.forename: Paul E
authors.initials: PE
authors.lastname: Orndorff
authors.forename: Christopher
authors.initials: C
authors.lastname: Elkins
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000008:administration & dosage* / Q000276:immunology; D001426:Bacterial Proteins / Q000276:immunology*; D002352:Carrier Proteins / Q000276:immunology*; D002602:Chancroid / Q000276:immunology / Q000473:pathology / Q000517:prevention & control*; D004195:Disease Models, Animal; D004423:Ear / Q000473:pathology; D006191:Haemophilus ducreyi / Q000276:immunology / Q000472:pathogenicity*; D006651:Histocytochemistry; D007106:Immune Sera / Q000008:administration & dosage* / Q000276:immunology; D007116:Immunization, Passive / Q000379:methods*; D050296:Microbial Viability; D008853:Microscopy; D011956:Receptors, Cell Surface / Q000276:immunology; D013552:Swine; D013553:Swine Diseases / Q000276:immunology / Q000517:prevention & control
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D002352:Carrier Proteins; D007106:Immune Sera; D011956:Receptors, Cell Surface; C017206:hemoglobin-binding protein, bacteria