Characterization and Vaccine Potential of Membrane Vesicles Produced by Francisella noatunensis subsp. orientalis in an Adult Zebrafish Model.
Vaccine development against extracellular bacteria has been important for the sustainability of the aquaculture industry. In contrast, infections with intracellular pathogens remain largely an unresolved problem.Francisella noatunensissubsp.orientalisis a Gram-negative, facultative intracellular bacterium that causes the disease francisellosis in fish. Francisellosis is commonly characterized as a chronic granulomatous disease with high morbidity and can result in high mortality depending on the host. In this study, we explored the potential of bacterial membrane vesicles (MVs) as a vaccine agent againstF. noatunensissubsp.orientalisBacterial MVs are spherical structures naturally released from the membrane of bacteria and are often enriched with selected bacterial components such as toxins and signaling molecules. MVs were isolated from broth-culturedF. noatunensissubsp.orientalisin the present work, and proteomic analysis by mass spectrometry revealed that MVs contained a variety of immunogenic factors, including the intracellular growth proteins IglC and IglB, known to be part of aFrancisellapathogenicity island (FPI), as well as outer membrane protein OmpA, chaperonin GroEL, and chaperone ClpB. By using flow cytometry and electron microscopy, we observed thatF. noatunensissubsp.orientalismainly infects myelomonocytic cells, bothin vivoandin vitroImmunization with MVs isolated fromF. noatunensissubsp.orientalisprotects zebrafish from subsequent challenge with a lethal dose ofF. noatunensissubsp.orientalisTo determine if MVs induce a typical acute inflammatory response, mRNA expression levels were assessed by quantitative real-time PCR. Expression oftnfa,il1b, andifng, as well asmhcii,mpeg1.1, andighm, was upregulated, thus confirming the immunogenic properties ofF. noatunensissubsp.orientalis-derived MVs.
Center of Integrative Microbial Evolution and Department of Pharmaceutical Biosciences, School of Pharmacy, Faculty of Mathematics and Natural Science, University of Oslo, Oslo, Norway.
Leidy
L
Lagos
Center of Integrative Microbial Evolution and Department of Pharmaceutical Biosciences, School of Pharmacy, Faculty of Mathematics and Natural Science, University of Oslo, Oslo, Norway.
Julia I
JI
Tandberg
Department of Biosciences, Faculty of Mathematics and Natural Science, University of Oslo, Oslo, Norway.
Urska
U
Repnik
Department of Food Safety & Infection Biology, Faculty of Veterinary Medicine and Biosciences, Norwegian University of Life Sciences, Oslo, Norway.
Preben
P
Boysen
Department of Production Animal Clinical Sciences, Norwegian University of Live Sciences, NMBU-School of Veterinary Science, Oslo, Norway.
Erik
E
Ropstad
Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia.
Deepa
D
Varkey
Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia.
Ian T
IT
Paulsen
Center of Integrative Microbial Evolution and Department of Pharmaceutical Biosciences, School of Pharmacy, Faculty of Mathematics and Natural Science, University of Oslo, Oslo, Norway hannewi@farmasi.uio.no.
Hanne C
HC
Winther-Larsen
D000375:Aging; D000818:Animals; D001426:Bacterial Proteins / Q000276:immunology*; D005393:Fish Diseases / Q000276:immunology / Q000517:prevention & control*; D005603:Francisella / Q000276:immunology*; D016905:Gram-Negative Bacterial Infections / Q000276:immunology / Q000517:prevention & control*; D014612:Vaccines / Q000276:immunology*; D015027:Zebrafish
D001426:Bacterial Proteins; D014612:Vaccines
Francisella noatunensis subsp. orientalis; MVs; fish pathogens; francisellosis; immune response; immunization; immunology; membrane vesicles; vaccine; zebrafish