title: Immunization with the Haemophilus ducreyi trimeric autotransporter adhesin DsrA with alum, CpG or imiquimod generates a persistent humoral immune response that recognizes the bacterial surface.
abstract: The Ducreyi serum resistance A (DsrA) protein of Haemophilus ducreyi belongs to a large family of multifunctional outer membrane proteins termed trimeric autotransporter adhesins responsible for resistance to the bactericidal activity of human complement (serum resistance), agglutination and adhesion. The ability of DsrA to confer serum resistance and bind extracellular matrix proteins lies in its N-terminal passenger domain. We have previously reported that immunization with a recombinant form of the passenger domain of DsrA, rNT-DsrA, in complete/incomplete Freund's adjuvant, protects against a homologous challenge in swine. We present herein the results of an immunogenicity study in mice aimed at investigating the persistence, type of immune response, and the effect of immunization route and adjuvants on surrogates of protection. Our results indicate that a 20 μg dose of rNT-DsrA administered with alum elicited antisera with comparable bacterial surface reactivity to that obtained with complete/incomplete Freund's adjuvant. At that dose, high titers and bacterial surface reactivity persisted for 211 days after the first immunization. Administration of rNT-DsrA with CpG or imiquimod as adjuvants elicited a humoral response with similar quantity and quality of antibodies (Abs) as seen with Freund's adjuvant. Furthermore, intramuscular administration of rNT-DsrA elicited high-titer Abs with significantly higher reactivity to the bacterial surface than those obtained with subcutaneous immunization. All rNT-DsrA/adjuvant combinations tested, save CpG, elicited a Th2-type response. Taken together, these findings show that a 20 μg dose of rNT-DsrA administered with the adjuvants alum, CpG or imiquimod elicits high-quality Abs with reactivity to the bacterial surface that could protect against an H. ducreyi infection.
authors.affiliation: Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, United States.
authors.forename: Melissa
authors.initials: M
authors.lastname: Samo
authors.affiliation: Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States.
authors.forename: Neelima R
authors.initials: NR
authors.lastname: Choudhary
authors.affiliation: Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, United States.
authors.forename: Kristina J
authors.initials: KJ
authors.lastname: Riebe
authors.affiliation: Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, United States.
authors.forename: Ivo
authors.initials: I
authors.lastname: Shterev
authors.affiliation: Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, United States; Department of Pathology, Duke University Medical Center, Durham, NC 27710, United States.
authors.forename: Herman F
authors.initials: HF
authors.lastname: Staats
authors.affiliation: Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, United States; Department of Pathology, Duke University Medical Center, Durham, NC 27710, United States; Department of Medicine, Duke University Medical Center, Durham, NC 27710, United States.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Sempowski
authors.affiliation: Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States. Electronic address: isabelle_leduc@med.unc.edu.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Leduc
mesh_terms: D018829:Adhesins, Bacterial / Q000276:immunology*; D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000534:Alum Compounds / Q000008:administration & dosage; D000634:Aminoquinolines / Q000008:administration & dosage; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001428:Bacterial Vaccines / Q000737:chemistry*; D018899:CpG Islands; D005260:Female; D005620:Freund's Adjuvant / Q000008:administration & dosage; D006191:Haemophilus ducreyi; D000077271:Imiquimod; D007106:Immune Sera / Q000276:immunology; D056724:Immunity, Humoral; D017578:Immunoglobulin Class Switching; D051379:Mice; D008807:Mice, Inbred BALB C; D000069320:Type V Secretion Systems / Q000276:immunology*
chemical_list: D018829:Adhesins, Bacterial; D000276:Adjuvants, Immunologic; D000534:Alum Compounds; D000634:Aminoquinolines; D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D007106:Immune Sera; D000069320:Type V Secretion Systems; C041524:aluminum sulfate; D005620:Freund's Adjuvant; D000077271:Imiquimod
keywords: DsrA; Haemophilus ducreyi; Trimeric autotransporter adhesin; Vaccine
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