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Ahlstrand T, Tuominen H, Beklen A, Torittu A, Oscarsson J, Sormunen R, Pöllänen MT, Permi P, Ihalin R. A novel intrinsically disordered outer membrane lipoprotein of Aggregatibacter actinomycetemcomitans binds various cytokines and plays a role in biofilm response to interleukin-1β and interleukin-8. Virulence 2016; 8:115-134. [PMID: 27459270 PMCID: PMC5383217 DOI: 10.1080/21505594.2016.1216294] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) do not have a well-defined and stable 3-dimensional fold. Some IDPs can function as either transient or permanent binders of other proteins and may interact with an array of ligands by adopting different conformations. A novel outer membrane lipoprotein, bacterial interleukin receptor I (BilRI) of the opportunistic oral pathogen Aggregatibacter actinomycetemcomitans binds a key gatekeeper proinflammatory cytokine interleukin (IL)-1β. Because the amino acid sequence of the novel lipoprotein resembles that of fibrinogen binder A of Haemophilus ducreyi, BilRI could have the potential to bind other proteins, such as host matrix proteins. However, from the tested host matrix proteins, BilRI interacted with neither collagen nor fibrinogen. Instead, the recombinant non-lipidated BilRI, which was intrinsically disordered, bound various pro/anti-inflammatory cytokines, such as IL-8, tumor necrosis factor (TNF)-α, interferon (IFN)-γ and IL-10. Moreover, BilRI played a role in the in vitro sensing of IL-1β and IL-8 because low concentrations of cytokines did not decrease the amount of extracellular DNA in the matrix of bilRI− mutant biofilm as they did in the matrix of wild-type biofilm when the biofilms were exposed to recombinant cytokines for 22 hours. BilRI played a role in the internalization of IL-1β in the gingival model system but did not affect either IL-8 or IL-6 uptake. However, bilRI deletion did not entirely prevent IL-1β internalization, and the binding of cytokines to BilRI was relatively weak. Thus, BilRI might sequester cytokines on the surface of A. actinomycetemcomitans to facilitate the internalization process in low local cytokine concentrations.
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Affiliation(s)
- Tuuli Ahlstrand
- a Department of Biochemistry , University of Turku , Turku , Finland
| | - Heidi Tuominen
- a Department of Biochemistry , University of Turku , Turku , Finland
| | - Arzu Beklen
- a Department of Biochemistry , University of Turku , Turku , Finland
| | - Annamari Torittu
- a Department of Biochemistry , University of Turku , Turku , Finland
| | - Jan Oscarsson
- b Oral Microbiology , Department of Odontology, Umeå University , Umeå , Sweden
| | - Raija Sormunen
- c Biocenter Oulu and Department of Pathology , University of Oulu , Oulu Finland
| | | | - Perttu Permi
- e Program in Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki , Helsinki , Finland.,f Department of Biological and Environmental Sciences , Nanoscience Center, University of Jyväskylä , Jyväskylä , Finland.,g Department of Chemistry , Nanoscience Center, University of Jyväskylä , Jyväskylä , Finland
| | - Riikka Ihalin
- a Department of Biochemistry , University of Turku , Turku , Finland
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Samo M, Choudhary NR, Riebe KJ, Shterev I, Staats HF, Sempowski GD, Leduc I. 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. Vaccine 2016; 34:1193-200. [PMID: 26812077 DOI: 10.1016/j.vaccine.2016.01.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 12/21/2015] [Accepted: 01/13/2016] [Indexed: 11/19/2022]
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.
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Affiliation(s)
- Melissa Samo
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, United States
| | - Neelima R Choudhary
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States
| | - Kristina J Riebe
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, United States
| | - Ivo Shterev
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, United States
| | - Herman F Staats
- 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
| | - Gregory D Sempowski
- 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
| | - Isabelle Leduc
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States.
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Fusco WG, Choudhary NR, Stewart SM, Alam SM, Sempowski GD, Elkins C, Leduc I. Defining Potential Vaccine Targets of Haemophilus ducreyi Trimeric Autotransporter Adhesin DsrA. Monoclon Antib Immunodiagn Immunother 2015; 34:73-82. [PMID: 25897604 PMCID: PMC4410285 DOI: 10.1089/mab.2014.0054] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 09/08/2014] [Indexed: 01/06/2023] Open
Abstract
Haemophilus ducreyi is the causative agent of the sexually transmitted genital ulcer disease chancroid. Strains of H. ducreyi are grouped in two classes (I and II) based on genotypic and phenotypic differences, including those found in DsrA, an outer membrane protein belonging to the family of multifunctional trimeric autotransporter adhesins. DsrA is a key serum resistance factor of H. ducreyi that prevents binding of natural IgM at the bacterial surface and functions as an adhesin to fibronectin, fibrinogen, vitronectin, and human keratinocytes. Monoclonal antibodies (MAbs) were developed to recombinant DsrA (DsrA(I)) from prototypical class I strain 35000HP to define targets for vaccine and/or therapeutics. Two anti-DsrAI MAbs bound monomers and multimers of DsrA from genital and non-genital/cutaneous H. ducreyi strains in a Western blot and reacted to the surface of the genital strains; however, these MAbs did not recognize denatured or native DsrA from class II strains. In a modified extracellular matrix protein binding assay using viable H. ducreyi, one of the MAbs partially inhibited binding of fibronectin, fibrinogen, and vitronectin to class I H. ducreyi strain 35000HP, suggesting a role for anti-DsrA antibodies in preventing binding of H. ducreyi to extracellular matrix proteins. Standard ELISA and surface plasmon resonance using a peptide library representing full-length, mature DsrAI revealed the smallest nominal epitope bound by one of the MAbs to be MEQNTHNINKLS. Taken together, our findings suggest that this epitope is a potential target for an H. ducreyi vaccine.
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Affiliation(s)
- William G. Fusco
- Department of Medicine, University of North Carolina at Chapel Hill, North Carolina
| | - Neelima R. Choudhary
- Department of Medicine, University of North Carolina at Chapel Hill, North Carolina
| | - Shelley M. Stewart
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina
| | - S. Munir Alam
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina
| | - Gregory D. Sempowski
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, North Carolina
| | - Christopher Elkins
- Department of Medicine, University of North Carolina at Chapel Hill, North Carolina
| | - Isabelle Leduc
- Department of Medicine, University of North Carolina at Chapel Hill, North Carolina
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Gaston JR, Roberts SA, Humphreys TL. Molecular phylogenetic analysis of non-sexually transmitted strains of Haemophilus ducreyi. PLoS One 2015; 10:e0118613. [PMID: 25774793 PMCID: PMC4361675 DOI: 10.1371/journal.pone.0118613] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 01/21/2015] [Indexed: 12/19/2022] Open
Abstract
Haemophilus ducreyi, the etiologic agent of chancroid, has been previously reported to show genetic variance in several key virulence factors, placing strains of the bacterium into two genetically distinct classes. Recent studies done in yaws-endemic areas of the South Pacific have shown that H. ducreyi is also a major cause of cutaneous limb ulcers (CLU) that are not sexually transmitted. To genetically assess CLU strains relative to the previously described class I, class II phylogenetic hierarchy, we examined nucleotide sequence diversity at 11 H. ducreyi loci, including virulence and housekeeping genes, which encompass approximately 1% of the H. ducreyi genome. Sequences for all 11 loci indicated that strains collected from leg ulcers exhibit DNA sequences homologous to class I strains of H. ducreyi. However, sequences for 3 loci, including a hemoglobin receptor (hgbA), serum resistance protein (dsrA), and a collagen adhesin (ncaA) contained informative amounts of variation. Phylogenetic analyses suggest that these non-sexually transmitted strains of H. ducreyi comprise a sub-clonal population within class I strains of H. ducreyi. Molecular dating suggests that CLU strains are the most recently developed, having diverged approximately 0.355 million years ago, fourteen times more recently than the class I/class II divergence. The CLU strains' divergence falls after the divergence of humans from chimpanzees, making it the first known H. ducreyi divergence event directly influenced by the selective pressures accompanying human hosts.
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Affiliation(s)
- Jordan R. Gaston
- Department of Biology, Allegheny College, Meadville, Pennsylvania, United States of America
| | - Sally A. Roberts
- Department of Microbiology, Auckland District Health Board, Auckland, New Zealand
| | - Tricia L. Humphreys
- Department of Biology, Allegheny College, Meadville, Pennsylvania, United States of America
- * E-mail:
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Fusco WG, Choudhary NR, Routh PA, Ventevogel MS, Smith VA, Koch GG, Almond GW, Orndorff PE, Sempowski GD, Leduc I. The Haemophilus ducreyi trimeric autotransporter adhesin DsrA protects against an experimental infection in the swine model of chancroid. Vaccine 2014; 32:3752-8. [PMID: 24844153 DOI: 10.1016/j.vaccine.2014.05.031] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 05/02/2014] [Accepted: 05/09/2014] [Indexed: 01/09/2023]
Abstract
Adherence of pathogens to cellular targets is required to initiate most infections. Defining strategies that interfere with adhesion is therefore important for the development of preventative measures against infectious diseases. As an adhesin to host extracellular matrix proteins and human keratinocytes, the trimeric autotransporter adhesin DsrA, a proven virulence factor of the Gram-negative bacterium Haemophilus ducreyi, is a potential target for vaccine development. A recombinant form of the N-terminal passenger domain of DsrA from H. ducreyi class I strain 35000HP, termed rNT-DsrAI, was tested as a vaccine immunogen in the experimental swine model of H. ducreyi infection. Viable homologous H. ducreyi was not recovered from any animal receiving four doses of rNT-DsrAI administered with Freund's adjuvant at two-week intervals. Control pigs receiving adjuvant only were all infected. All animals receiving the rNT-DsrAI vaccine developed antibody endpoint titers between 3.5 and 5 logs. All rNT-DsrAI antisera bound the surface of the two H. ducreyi strains used to challenge immunized pigs. Purified anti-rNT-DsrAI IgG partially blocked binding of fibrinogen at the surface of viable H. ducreyi. Overall, immunization with the passenger domain of the trimeric autotransporter adhesin DsrA accelerated clearance of H. ducreyi in experimental lesions, possibly by interfering with fibrinogen binding.
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Affiliation(s)
- William G Fusco
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Neelima R Choudhary
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Patty A Routh
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA
| | - Melissa S Ventevogel
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Valerie A Smith
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Gary G Koch
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Glen W Almond
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA
| | - Paul E Orndorff
- College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA
| | - Gregory D Sempowski
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Isabelle Leduc
- Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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