Hanne Cecilie Winther-Larsen

• Cordero, Christian P.; Brenne, Hanne Britt; Ytteborg, Elisabeth; Hansen, Miroslava; Johansen, Lill-Heidi & Vanrompay, Daisy [Show all 8 contributors for this article] (2026). Immune responses in the olfactory organ and brain of Atlantic cod (Gadus morhua) following nasal vaccination against Francisella noatunensis. Fish and Shellfish Immunology. ISSN 1050-4648. p. 1–40. doi: 10.1016/j.fsi.2026.111767. Full text in Research Archive Show summary

  Bacterial infections caused by the intracellular bacterium Francisella noatunensis pose a major health challenge in Atlantic cod (Gadus morhua), largely due to the lack of effective prophylactic and therapeutic measures. Here we evaluated the immune and physiological responses of cod to two candidate live attenuated vaccines (i.e. clpB and iglC) against F. noatunensis delivered intranasally. These experimental vaccines were constructed by a single knockout mutation of a virulence gene in F. noatunensis. Cod was vaccinated intranasally and reared for 45 days until infection with the wild-type strain Francisella noatunenesis subp. noatunensis and further reared for 47 days until termination. Given the chosen delivery route, our analyses were focused on the olfactory organ and brain of cod. Infected cod presented classic gross pathologies of francisellosis, including multi-organ nodulations, splenomegaly, and hepatomegaly. Among the vaccine candidates, the clpB-vaccinated group demonstrated upregulated expression of immune response genes in both the olfactory organ and brain, exhibited the lowest nodulation score, and showed minimal histological alterations in the olfactory organ. To further explore the physiological consequences of the clpB mutant, shotgun proteomics was performed in selected olfactory organ and brain of vaccinated cod. We identified 404 differentially expressed proteins (DEPs) in the brain and 241 in the olfactory organ with 17 DEPs common to both organs. These DEPs were mostly involved in cellular signalling, transmembrane internalisation, enzymatic processes, and important immune response pathways, such as immune recruitment and activation, the respiratory burst reaction, and apoptosis. These findings suggest that the clpB-attenuated vaccine holds promise as a candidate vaccine against F. noatunensis and provides valuable insights into the mechanisms of immune modulation.

• Hovd, Rebekka Rolfsnes; Kaupang, Åsmund; Rongved, Pål; Kildahl-Andersen, Geir; Hylland, Knut Tormodssønn & Hovland, Ragnar [Show all 9 contributors for this article] (2025). APC24-7, a covalent combination of boronic acid and chelator moieties, restores β-lactam efficiency against metallo-β-lactamase-producers. mSphere. 10(12). doi: 10.1128/msphere.00418-25. Full text in Research Archive Show summary

  β-Lactam/β-lactamase inhibitor combinations have significantly improved treatment outcomes for infections caused by serine β-lactamase (SBL)-producing pathogens. However, the continued emergence and spread of metallo-β-lactamases (MBLs), for which no clinically approved inhibitors currently exist, poses a serious threat to the long-term effectiveness of β-lactam-based therapies. To bridge this therapeutic gap, the boronic acid transition state analog, taniborbactam (Venatorx Pharmaceuticals), was developed, targeting SBLs and widespread MBLs such as NDM-1 and VIM-2. However, taniborbactam-escape variants have been detected among various MBL enzymes, including members of the NDM and IMP families. Here, we explored whether covalently combining two complementary inhibitor structures, a boronic acid transition state analog and a dipicolyl ethylenediamine-based metal chelator, can restore β-lactam susceptibility in MBL-producing bacterial strains, including taniborbactam-escape variants. APC24-7 successfully sensitized clinical isolates of SBL- and MBL-producing Klebsiella pneumoniae and Escherichia coli to meropenem. While APC24-7 demonstrated similarities in resensitization behavior to taniborbactam against a wide range of isogenic E. coli expressing single SBLs, APC24-7 reversed NDM-9- or IMP-26-mediated meropenem resistance more efficiently. To investigate the potential role of the chelator motif in the MBL inhibition of APC24-7, susceptibility tests were conducted with an excess of exogenous Zn² + . APC24-7-mediated resensitization remained unaffected in the presence of Zn² + for strains producing NDM-1 and VIM-2. However, its ability to reverse NDM-9- and IMP-26-mediated meropenem resistance was attenuated upon Zn² + supplementation. These findings demonstrate that combining functionally complementary chemical structures, such as chelators and boronic acids, can aid in expanding the resensitization ability of existing β-lactamase inhibitors. IMPORTANCE The ability of bacteria such as Klebsiella pneumoniae and Escherichia coli to circumvent antimicrobial chemotherapy has become a global public health crisis. The high prevalence of β-lactamase enzymes capable of rendering our most prescribed antibiotics, the β-lactams (BLs) inactive, has left us with few available treatment options against infections caused by these bacteria. The use of small molecules that inhibit especially serine β-lactamases has substantially prolonged the lifetime of BL antibiotics. Yet, most clinically available inhibitors either do not possess or have limited ability to reverse resistance conferred by metallo-β-lactamase (MBL) enzymes. Combining chelator and transition state analog technology, our hybrid compound restores the effectiveness of BL antibiotics in cases of resistance conferred by both serine β-lactamases (SBLs) and MBLs. Our approach of covalently combining a chelator with an existing SBL inhibitor scaffold offers a promising solution for managing life-threatening infections and prolonging the use of clinically available BLs.

• Ortiz-Severín, Javiera; Tandberg, Julia Isabel; Winther-Larsen, Hanne Cecilie; Allende, Miguel L.; Cambiazo, Verónica & Chávez, Francisco P. (2025). In vivo host-pathogen dynamics and immune responses to Piscirickettsia salmonis using the zebrafish model. Microbial Pathogenesis. ISSN 0882-4010. 200. doi: 10.1016/j.micpath.2025.107349. Full text in Research Archive
• Zakhartseva, Ekaterina Avershina; Qureshi, Arfa Irej; Winther-Larsen, Hanne Cecilie & Rounge, Trine Ballestad (2025). Challenges in capturing the mycobiome from shotgun metagenome data: lack of software and databases. Microbiome. 13(1). doi: 10.1186/s40168-025-02048-3. Full text in Research Archive Show summary

  Background The mycobiome, representing the fungal component of microbial communities, is increasingly acknowledged as an integral part of the gut microbiome. However, research in this area remains relatively limited. The characterization of mycobiome taxa from metagenomic data is heavily reliant on the quality of the software and databases. In this study, we evaluated the feasibility of mycobiome profiling using existing bioinformatics tools on simulated fungal metagenomic data. Results We identified seven tools claiming to perform taxonomic assignment of fungal shotgun metagenomic sequences. One of these was outdated and required substantial modifications of the code to be functional and was thus excluded. To evaluate the accuracy of identification and relative abundance of the remaining tools (Kraken2, MetaPhlAn4, EukDetect, FunOMIC, MiCoP, and HumanMycobiomeScan), we constructed 18 mock communities of varying species richness and abundance levels. The mock communities comprised up to 165 fungal species belonging to the phyla Ascomycota and Basidiomycota, commonly found in gut microbiomes. Of the tools, FunOMIC and HumanMycobiomeScan needed source code modifications to run. Notably, only one species, Candida orthopsilosis, was consistently identified by all tools across all communities where it was included. Increasing community richness improved precision of Kraken2 and the relative abundance accuracy of all tools on species, genus, and family levels. MetaPhlAn4 accurately identified all genera present in the communities and FunOMIC identified most species. The top three tools for overall accuracy in both identification and relative abundance estimation were EukDetect, MiCoP, and FunOMIC, respectively. Adding 90% and 99% bacterial background did not significantly impact these tools’ performance. Among the whole genome reference tools (Kraken2, HMS, and MiCoP), MiCoP exhibited the highest accuracy when the same reference database was used. Conclusion Our survey of mycobiome-specific software revealed a very limited selection of such tools and their poor robustness due to error-prone software, along with a significant lack of comprehensive databases enabling characterization of the mycobiome. None of the implemented tools fully agreed on the mock community profiles. FunOMIC recognized most of the species, but EukDetect and MiCoP provided predictions that were closest to the correct compositions. The bacterial background did not impact these tools’ performance. Video Abstract

• Carril, Gabriela Paz Leiva; Winther-Larsen, Hanne Cecilie; Løvoll, Marie Therese & Sørum, Henning (2024). Differential Transcriptomic Profile of Piscirickettsia salmonis LF-89 and EM-90 During an In Vivo Spatial Separation Co-Culture in Atlantic Salmon. Microorganisms. 12(12). doi: 10.3390/microorganisms12122480. Full text in Research Archive
• Carril, Gabriela Paz Leiva; Lange, Byron Maximiliano Morales; Løvoll, Marie Therese; Inami, Makoto; Winther-Larsen, Hanne Cecilie & Øverland, Margareth [Show all 7 contributors for this article] (2024). Salmonid Rickettsial Septicemia (SRS) disease dynamics and Atlantic salmon immune response to Piscirickettsia salmonis LF-89 and EM-90 co-infection. Veterinary research (VR). ISSN 0928-4249. 55(1). doi: 10.1186/s13567-024-01356-0. Full text in Research Archive Show summary

  In Chile, Piscirickettsia salmonis contains two genetically isolated genogroups, LF-89 and EM-90. However, the impact of a potential co-infection with these two variants on Salmonid Rickettsial Septicemia (SRS) in Atlantic salmon (Salmo salar) remains largely unexplored. In our study, we evaluated the effect of P. salmonis LF-89-like and EM-90-like co-infection on post-smolt Atlantic salmon after an intraperitoneal challenge to compare changes in disease dynamics and host immune response. Co-infected fish had a significantly lower survival rate (24.1%) at 21 days post-challenge (dpc), compared with EM-90-like single-infected fish (40.3%). In contrast, all the LF-89-like single-infected fish survived. In addition, co-infected fish presented a higher presence of clinical lesions than any of the single-infected fish. The gene expression of salmon immune-related biomarkers evaluated in the head kidney, spleen, and liver showed that the EM-90-like isolate and the co-infection induced the up-regulation of cytokines (e.g., il-1β, ifnγ, il8, il10), antimicrobial peptides (hepdicin) and pattern recognition receptors (PRRs), such as TLR5s. Furthermore, in serum samples from EM-90-like and co-infected fish, an increase in the total IgM level was observed. Interestingly, specific IgM against P. salmonis showed greater detection of EM-90-like antigens in LF-89-like infected fish serum (cross-reaction). These data provide evidence that P. salmonis LF-89-like and EM-90-like interactions can modulate SRS disease dynamics in Atlantic salmon, causing a synergistic effect that increases the severity of the disease and the mortality rate of the fish. Overall, this study contributes to achieving a better understanding of P. salmonis population dynamics.

• Mertes, Verena; Saragliadis, Athanasios; Mascherin, E; Tysvær, Ellen-Beate; Roos, Norbert & Linke, Dirk [Show all 7 contributors for this article] (2024). Recombinant expression of Yersinia ruckeri outer membrane proteins in Escherichia coli extracellular vesicles. Protein Expression and Purification. ISSN 1046-5928. 215. doi: 10.1016/j.pep.2023.106409. Full text in Research Archive Show summary

  The secretion of extracellular vesicles (EVs) is a common process in Gram-negative bacteria and can be exploited for biotechnological applications. EVs pose a self-adjuvanting, non-replicative vaccine platform, where membrane and antigens are presented to the host immune system in a non-infectious fashion. The secreted quantity of EVs varies between Gram-negative bacterial species and is comparatively high in the model bacterium E. coli. The outer membrane proteins OmpA and OmpF of the fish pathogen Y. ruckeri have been proposed as vaccine candidates to prevent enteric redmouth disease in aquaculture. In this work, Y.ruckeri OmpA or OmpF were expressed in E. coli and recombinant EVs were isolated. To avoid competition between endogenous E. coli OmpA or OmpF, Y. ruckeri OmpA and OmpF were expressed in E. coli strains lacking ompA, ompF, and in a quadruple knockout strain where the four major outer membrane protein genes ompA, ompC, ompF and lamB were removed. Y.ruckeri OmpA and OmpF were successfully expressed in EVs derived from the E. coli mutants as verified by SDS-PAGE, heat modifiability and proteomic analysis using mass-spectrometry. Transmission electron microscopy revealed the presence of EVs in all E. coli strains, and increased EV concentrations were detected when expressing Y. ruckeri OmpA or OmpF in recombinant EVs compared to empty vector controls as verified by nanoparticle tracking analysis. These results show that E. coli can be utilized as a vector for production of EVs expressing outer membrane antigens from Y. ruckeri.

• Oliver, Cristian; Coronado, José Leonardo; Martínez, Danixa; Kashulin, Alexander; Lagos, Leidy & Ciani, Elia [Show all 11 contributors for this article] (2023). Outer membrane vesicles from Piscirickettsia salmonis induce the expression of inflammatory genes and production of IgM in Atlantic salmon Salmo salar. Fish and Shellfish Immunology. ISSN 1050-4648. 139. doi: 10.1016/j.fsi.2023.108887. Full text in Research Archive
• Nystedt, Helene Liepelt; Grønlien, Krister Gjestvang; Rolfsnes, Rebekka Rekkedal; Winther-Larsen, Hanne Cecilie; Økstad, Ole Andreas & Tønnesen, Hanne Hjorth (2023). Neutral natural deep eutectic solvents as anti-biofilm agents. Biofilm. 5. doi: 10.1016/j.bioflm.2023.100114. Full text in Research Archive Show summary

  Natural deep eutectic solvents (NADES) are a class of liquids with promising properties as components in pharmaceutical formulations, such as a low toxicity profile, biodegradability and versatility. Recently, their potential use as anti-biofilm agents has been proposed, due to their ability to solubilize and stabilize biological macromolecules. In the current work, the ability to break down biofilm matrix and the biofilm killing activity of three NADES of neutral pH were investigated against Staphylococcus aureus ATCC 6538 and Pseudomonas aeruginosa ATCC 9027 biofilms. The tested NADES were choline chloride:xylitol (ChX), choline chloride:glycerol (ChG) and betaine:sucrose (BS). Two of the NADES (ChX and ChG) significantly reduced the number of remaining viable cells of both bacterial species in pre-formed biofilm by 4–6 orders of magnitude, while the average biofilm biomass removal for all NADES was 27–67% (S. aureus) and 34–49% (P. aeruginosa). The tested NADES also inhibited biofilm formation of both bacterial species at concentrations at or below 0.5 x the minimal inhibitory concentration (MIC), possibly in part due to observed restrictions imposed by NADES on planktonic growth. These results demonstrate the potential value of neutral NADES as anti-biofilm agents in future antimicrobial preparations.

• Leiva, Gabriela Paz Carril; Winther-Larsen, Hanne Cecilie; Løvoll, Marie Therese & Sørum, Henning (2023). Cohabitation of Piscirickettsia salmonis genogroups (LF-89 and EM-90): synergistic effect on growth dynamics. Frontiers in Cellular and Infection Microbiology. 13. doi: 10.3389/fcimb.2023.1253577. Full text in Research Archive
• Lekang, Katrine; Shekhar, Sudhanshu; Berild, Dag; Petersen, Fernanda Cristina & Winther-Larsen, Hanne Cecilie (2022). Effects of different amoxicillin treatment durations on microbiome diversity and composition in the gut. PLOS ONE. 17(10), p. e0275737–e0275737. doi: 10.1371/journal.pone.0275737. Full text in Research Archive Show summary

  Antibiotics seize an effect on bacterial composition and diversity and have been demonstrated to induce disruptions on gut microbiomes. This may have implications for human health and wellbeing, and an increasing number of studies suggest a link between the gut microbiome and several diseases. Hence, reducing antibiotic treatments may be beneficial for human health status. Further, antimicrobial resistance (AMR) is an increasing global problem that can be counteracted by limiting the usage of antibiotics. Longer antibiotic treatments have been demonstrated to increase the development of AMR. Therefore, shortening of antibiotic treatment durations, provided it is safe for patients, may be one measure to reduce AMR. In this study, the objective was to investigate effects of standard and reduced antibiotic treatment lengths on gut microbiomes using a murine model. Changes in the murine gut microbiome was assessed after using three different treatment durations of amoxicillin (3, 7 or 14 days) as well as a control group not receiving amoxicillin. Fecal samples were collected before and during the whole experiment, until three weeks past end of treatment. These were further subject for 16S rRNA Illumina MiSeq sequencing. Our results demonstrated significant changes in bacterial diversity, richness and evenness during amoxicillin treatment, followed by a reversion in terms of alpha-diversity and abundance of major phyla, after end of treatment. However, a longer restitution time was indicated for mice receiving amoxicillin for 14 days, and phylum Patescibacteria did not fully recover. In addition, an effect on the composition of Firmicutes was indicated to last for at least three weeks in mice treated with amoxicillin for 14 days. Despite an apparently reversion to a close to original state in overall bacterial diversity and richness, the results suggested more durable changes in lower taxonomical levels. We detected several families, genera and ASVs with significantly altered abundance three weeks after exposure to amoxicillin, as well as bacterial taxa that appeared significantly affected by amoxicillin treatment length. This may strengthen the argument for shorter antibiotic treatment regimens to both limit the emergence of antibiotic resistance and risk of gut microbiome disturbance.

• Zhu, Zhuang; Antenucci, Fabio; Winther-Larsen, Hanne Cecilie; Skovgaard, Kerstin & Bojesen, Anders Miki (2022). Outer Membrane Vesicles of Actinobacillus pleuropneumoniae Exert Immunomodulatory Effects on Porcine Alveolar Macrophages. Microbiology spectrum. 10(5). doi: 10.1128/spectrum.01819-22. Full text in Research Archive
• Coggan, Kimberly A.; Higgs, Matthew G.; Brutinel, Evan D.; Marden, Jeremiah N.; Intile, Peter J. & Winther-Larsen, Hanne Cecilie [Show all 9 contributors for this article] (2022). Global Regulatory Pathways Converge To Control Expression of Pseudomonas aeruginosa Type IV Pili. mBio. ISSN 2161-2129. 13(1). doi: 10.1128/MBIO.03696-21. Full text in Research Archive
• Thapa, Raj Kumar; Winther-Larsen, Hanne Cecilie; Diep, Dzung B. & Tønnesen, Hanne Hjorth (2021). Photostability studies of GarKS peptides for topical formulation development. European Journal of Pharmaceutical Sciences. ISSN 0928-0987. 158. doi: 10.1016/j.ejps.2020.105652. Full text in Research Archive
• Ortiz-Severín, Javiera; Tandberg, Julia Isabel; Winther-Larsen, Hanne Cecilie; Chávez, Francisco P. & Cambiazo, Verónica (2021). Comparative analysis of salmon cell lines and zebrafish primary cell cultures infection with the fish pathogen piscirickettsia salmonis. Microorganisms. 9(12). doi: 10.3390/microorganisms9122516. Full text in Research Archive
• Mertes, Verena; Kashulin, Alexander; Lagos, Leidy; Ciani, Elia; Colquhoun, Duncan John & Haslene-Hox, Hanne [Show all 9 contributors for this article] (2021). The Use of Extracellular Membrane Vesicles for Immunization against Francisellosis in Nile Tilapia (Oreochromis niloticus) and Atlantic cod (Gadus morhua L.). Vaccines. 9(1). doi: 10.3390/vaccines9010034. Full text in Research Archive Show summary

  Francisellosis in fish is caused by the facultative intracellular Gram-negative bacterial pathogens Francisella noatunensis ssp. noatunensis and Francisella orientalis. The disease is affecting both farmed and wild fish worldwide and no commercial vaccines are currently available. In this study, we tested isolated membrane vesicles (MVs) as possible vaccine candidates based on previous trials in zebrafish (Danio rerio) indicating promising vaccine efficacy. Here, the MV vaccine-candidates were tested in their natural hosts, Atlantic cod (Gadus morhua L.) and Nile tilapia (Oreochromis niloticus). Injection of MVs did not display any toxicity or other negative influence on the fish and gene expression analysis indicated an influence on the host immune response. However, unlike in other tested fish species, a protective immunity following vaccine application and immunization period could not be detected in the Atlantic cod or tilapia. Further in vivo studies are required to achieve a better understanding of the development of immunological memory in different fish species.

• Thapa, Raj Kumar; Winther-Larsen, Hanne Cecilie; Ovchinnikov, Kirill; Carlsen, Harald; Diep, Dzung B. & Tønnesen, Hanne Hjorth (2021). Hybrid hydrogels for bacteriocin delivery to infected wounds. European Journal of Pharmaceutical Sciences. ISSN 0928-0987. 166, p. 1–10. doi: 10.1016/j.ejps.2021.105990. Full text in Research Archive
• Antenucci, Fabio; Ovsepian, Armen; Wróbel, Agnieszka Ewelina; Winther-Larsen, Hanne Cecilie & Bojesen, Anders Miki (2020). Design and characterization of a novel tool for the antigenic enrichment of actinobacillus pleuropneumoniae outer membrane. Pathogens. ISSN 2076-0817. 9(12). doi: 10.3390/pathogens9121014. Full text in Research Archive
• Thapa, Raj Kumar; Winther-Larsen, Hanne Cecilie; Diep, Dzung B. & Tønnesen, Hanne Hjorth (2020). Preformulation studies on novel garvicin KS peptides for topical applications. European Journal of Pharmaceutical Sciences. ISSN 0928-0987. 151. doi: 10.1016/j.ejps.2020.105333. Full text in Research Archive
• Langlete, Petter; Krabberød, Anders Kristian & Winther-Larsen, Hanne Cecilie (2019). Vesicles from vibrio cholerae contain AT-rich DNA and shorter mRNAs that do not correlate with their protein products. Frontiers in Microbiology. 10, p. 1–16. doi: 10.3389/fmicb.2019.02708. Full text in Research Archive Show summary

  Extracellular vesicles secreted by Gram-negative bacteria have proven to be important in bacterial defense, communication and host-pathogen relationships. They resemble smaller versions of the bacterial mother cell, with similar contents of proteins, LPS, DNA, and RNA. Vesicles can elicit a protective immune response in a range of hosts, and as vaccine candidates, it is of interest to properly characterize their cargo. Genetic sequencing data is already available for vesicles from several bacterial strains, but it is not yet clear how the genetic makeup of vesicles differ from that of their parent cells, and which properties may characterize enriched genetic material. The present study provides evidence for DNA inside vesicles from Vibrio cholerae O395, and key characteristics of their genetic and proteomic content are compared to that of whole cells. DNA analysis reveals enrichment of fragments containing ToxR binding sites, as well as a positive correlation between AT-content and enrichment. Some mRNAs were highly enriched in the vesicle fraction, such as membrane protein genes ompV, ompK, and ompU, DNA-binding protein genes hupA, hupB, ihfB, fis, and ssb, and a negative correlation was found between mRNA enrichment and transcript length, suggesting mRNA inclusion in vesicles may be a size-dependent process. Certain non-coding and functional RNAs were found to be enriched, such as VrrA, GcvB, tmRNA, RNase P, CsrB2, and CsrB3. Mass spectrometry revealed enrichment of outer membrane proteins, known virulence factors, phage components, flagella and extracellular proteins in the vesicle fraction, and a low, negative correlation was found between transcript-, and protein enrichment. This result opposes the hypothesis that a significant degree of protein translation occurs in vesicles after budding. The abundance of viral-, and flagellar proteins in the vesicle fraction underlines the importance of purification during vesicle isolation.

• Kumar, Sheemal S.; Tandberg, Julia Isabel; Penesyan, Anahit; Elbourne, Liam D. H.; Suarez-Bosche, Nadia & Don, Emily [Show all 11 contributors for this article] (2018). Dual Transcriptomics of Host-Pathogen Interaction of Cystic Fibrosis Isolate Pseudomonas aeruginosa PASS1 With Zebrafish. Frontiers in Cellular and Infection Microbiology. doi: 10.3389/fcimb.2018.00406. Full text in Research Archive Show summary

  Pseudomonas aeruginosa is a significant cause of mortality in patients with cystic fibrosis (CF). To explore the interaction of the CF isolate P. aeruginosa PASS1 with the innate immune response, we have used Danio rerio (zebrafish) as an infection model. Confocal laser scanning microscopy (CLSM) enabled visualization of direct interactions between zebrafish macrophages and P. aeruginosa PASS1. Dual RNA-sequencing of host-pathogen was undertaken to profile RNA expression simultaneously in the pathogen and the host during P. aeruginosa infection. Following establishment of infection in zebrafish embryos with PASS1, 3 days post infection (dpi), there were 6739 genes found to be significantly differentially expressed in zebrafish and 176 genes in PASS1. A range of virulence genes were upregulated in PASS1, including genes encoding pyoverdine biosynthesis, flagellin, non-hemolytic phospholipase C, proteases, superoxide dismutase and fimbrial subunits. Additionally, iron and phosphate acquisition genes were upregulated in PASS1 cells in the zebrafish. Transcriptional changes in the host immune response genes highlighted phagocytosis as a key response mechanism to PASS1 infection. Transcriptional regulators of neutrophil and macrophage phagocytosis were upregulated alongside transcriptional regulators governing response to tissue injury, infection, and inflammation. The zebrafish host showed significant downregulation of the ribosomal RNAs and other genes involved in translation, suggesting that protein translation in the host is affected by PASS1 infection.

• Tandberg, Julia Isabel; Rojas, Leidy Ximena Lagos; Ropstad, Erik; Smistad, Gro; Hiorth, Marianne & Winther-Larsen, Hanne Cecilie (2018). The use of chitosan-coated membrane vesicles for immunization against salmonid rickettsial septicemia in an adult zebrafish model. Zebrafish. ISSN 1545-8547. 15(4), p. 372–381. doi: 10.1089/zeb.2017.1556. Full text in Research Archive
• Pöthig, Alexander; Sara, Ahmed; Winther-Larsen, Hanne Cecilie; Guan, Shengyang; Altmann, Philipp J. & Kundermann, Jürgen [Show all 9 contributors for this article] (2018). Antimicrobial Activity and Cytotoxicity of Ag(I) and Au(I) Pillarplexes. Frontiers in Chemistry. 6. doi: 10.3389/fchem.2018.00584. Full text in Research Archive
• Lampe, Elisabeth Opsjøn; Zingmark, Carl; Tandberg, Julia Isabel; Thrane, Ida Marie Paulsen; Brudal, Espen & Sjöstedt, Anders [Show all 7 contributors for this article] (2017). Francisella noatunensis subspecies noatunensis clpB deletion mutant impairs development of francisellosis in a zebrafish model. Vaccine. ISSN 0264-410X. 35(52), p. 7264–7272. doi: 10.1016/j.vaccine.2017.11.009. Full text in Research Archive Show summary

  Keywords: Atlantic cod, Francisella noatunensis, Francisellosis, ClpB, Immunization, Zebrafish

• Ulanova, Lilia; Pinheiro, Marina; Vibe, Carina Beatrice; Nunes, Clàudia; Misaghian, Dorna & Wilson, Steven Ray Haakon [Show all 11 contributors for this article] (2017). Treatment of Francisella infections via PLGA-and lipid-based nanoparticle delivery of antibiotics in a zebrafish model. Diseases of Aquatic Organisms. ISSN 0177-5103. 125(1), p. 19–29. doi: 10.3354/dao03129. Full text in Research Archive
• Lampe, Elisabeth Opsjøn; Tandberg, Julia Isabel; Rishovd, Anne-Lise & Winther-Larsen, Hanne Cecilie (2017). Francisella noatunensis ssp. noatunensis iglC deletion mutant protects adult zebrafish challenged with acute mortality dose of wild-type strain. Diseases of Aquatic Organisms. ISSN 0177-5103. 123(2), p. 123–140. doi: 10.3354/dao03087. Full text in Research Archive
• Oliver, Cristian; Hernández, Mauricio Alejandro; Tandberg, Julia Isabel; Valenzuela, Karla Natalia; Rojas, Leidy Ximena Lagos & Haro, Ronie E. [Show all 15 contributors for this article] (2017). The proteome of biologically active membrane vesicles from Piscirickettsia salmonis LF-89 type strain identifies plasmid-encoded putative toxins. Frontiers in Cellular and Infection Microbiology. 7:420, p. 1–15. doi: 10.3389/fcimb.2017.00420. Full text in Research Archive
• Brenz, Yannick Pirmin; Ohnezeit, Denise; Winther-Larsen, Hanne Cecilie & Hagedorn, Monica (2017). Nramp1 and NrampB Contribute to Resistance against Francisella in Dictyostelium. Frontiers in Cellular and Infection Microbiology. 7. doi: 10.3389/fcimb.2017.00282. Full text in Research Archive
• Brenz, Yannick Pirmin; Winther-Larsen, Hanne Cecilie & Hagedorn, Monica (2017). Expanding Francisella models: Pairing up the soil amoeba Dictyostelium with aquatic Francisella. International Journal of Medical Microbiology. ISSN 1438-4221. 308(1), p. 32–40. doi: 10.1016/j.ijmm.2017.08.001. Full text in Research Archive
• Karlsen, Christian; Ottem, Karl Fredrik; Brevik, Øyvind Jakobsen; Davey, Marie Louise; Sørum, Henning & Winther-Larsen, Hanne Cecilie (2017). The environmental and host-associated bacterial microbiota of Arctic seawater-farmed Atlantic salmon with ulcerative disorders. Journal of Fish Diseases. ISSN 0140-7775. 40(11), p. 1645–1663. doi: 10.1111/jfd.12632. Full text in Research Archive
• Lagos, Leidy; Tandberg, Julia Isabel; Becker, María Inés & Winther-Larsen, Hanne Cecilie (2017). Immunomodulatory properties of Concholepas concholepas hemocyanin against francisellosis in a zebrafish model. Fish and Shellfish Immunology. ISSN 1050-4648. 67, p. 571–574. doi: 10.1016/j.fsi.2017.06.046. Full text in Research Archive Show summary

  The development of vaccines for aquaculture has been an important milestone in providing a continuous and sustainable production. Most of the vaccines currently on the market for aquaculture include oil as adjuvant. Nevertheless, several studies reported an occurrence of side effects after their use in farmed fish. As a result, there is a need for new and improved adjuvants that can stimulate the immune system while causing as few side-effects as possible. Hemocyanins are versatile macromolecules with strong immunogenic and immunomodulatory properties. Due to these characteristics, hemocyanin from Concholepas concholepas (CCH) has been biochemically characterized and evaluated as vaccine adjuvant in mice and humans. Francisellosis is a chronic granulomatous disease, which can result in high mortality depending on the host. The disease is caused by the facultative intracellular Gram-negative bacteria Francisella noatunensis, which remains an unsolved problem for the aquaculture, as no efficient vaccines are available. The aim of the present work was to investigate the immunoregulatory properties of CCH against francisellosis in an experimental zebrafish model. When immunized with CCH, zebrafish were protected from subsequent challenge with a lethal dose of Francisella noatunensis subsp. orientalis. Subsequently the mRNA expression levels of several immune-related genes were studied, including mhcii, il12a, tnfα and ifng1-1. Taken together, the data report the immunoregulatory properties of CCH and its potential use as a vaccine adjuvant for aquaculture.

• Lagos, Leidy; Tandberg, Julia Isabel; Kashulin, Alexander; Colquhoun, Duncan John; Sørum, Henning & Winther-Larsen, Hanne Cecilie (2017). Isolation and Characterization of Serum Extracellular Vesicles (EVs) from Atlantic Salmon Infected with Piscirickettsia Salmonis. Proteomes. 5(4). doi: 10.3390/proteomes5040034. Full text in Research Archive Show summary

  Secretion of extracellular vesicles (EVs) is a common feature of both eukaryotic and prokaryotic cells. Isolated EVs have been shown to contain different types of molecules, including proteins and nucleic acids, and are reported to be key players in intercellular communication. Little is known, however, of EV secretion in fish, or the effect of infection on EV release and content. In the present study, EVs were isolated from the serum of healthy and Piscirickettsia salmonis infected Atlantic salmon in order to evaluate the effect of infection on EV secretion. P. salmonis is facultative intracellular bacterium that causes a systemic infection disease in farmed salmonids. EVs isolated from both infected and non-infected fish had an average diameter of 230–300 nm, as confirmed by transmission electron microscopy, nanoparticle tracking, and flow cytometry. Mass spectrometry identified 180 proteins in serum EVs from both groups of fish. Interestingly, 35 unique proteins were identified in serum EVs isolated from the fish infected with P. salmonis. These unique proteins included proteasomes subunits, granulins, and major histocompatibility class I and II. Our results suggest that EV release could be part of a mechanism in which host stimulatory molecules are released from infected cells to promote an immune response.

• Lagos, Leidy; Tandberg, Julia Isabel; Repnik, Urska; Boysen, Preben; Ropstad, Erik & Varkey, Deepa Ruth [Show all 8 contributors for this article] (2017). Characterization and Vaccine Potential of Membrane Vesicles Produced by Francisella noatunensis subsp. orientalis in an Adult Zebrafish Model. Clinical and Vaccine Immunology. ISSN 1556-6811. 24(5). doi: 10.1128/CVI.00557-16. Full text in Research Archive Show summary

  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 noatunensis subsp. orientalis is 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 against F. noatunensis subsp. orientalis. Bacterial 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-cultured F. noatunensis subsp. orientalis in 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 a Francisella pathogenicity island (FPI), as well as outer membrane protein OmpA, chaperonin GroEL, and chaperone ClpB. By using flow cytometry and electron microscopy, we observed that F. noatunensis subsp. orientalis mainly infects myelomonocytic cells, both in vivo and in vitro. Immunization with MVs isolated from F. noatunensis subsp. orientalis protects zebrafish from subsequent challenge with a lethal dose of F. noatunensis subsp. orientalis. To determine if MVs induce a typical acute inflammatory response, mRNA expression levels were assessed by quantitative real-time PCR. Expression of tnfa, il1b, and ifng, as well as mhcii, mpeg1.1, and ighm, was upregulated, thus confirming the immunogenic properties of F. noatunensis subsp. orientalis-derived MVs.

• Tandberg, Julia Isabel; Oliver, Cristian; Lagos, Leidy; Gaarder, Mona; Yáñez, Alejandro J. & Ropstad, Erik [Show all 7 contributors for this article] (2017). Membrane vesicles from Piscirickettsia salmonis induce protective immunity and reduce development of salmonid rickettsial septicemia in an adult zebrafish model. Fish and Shellfish Immunology. ISSN 1050-4648. 67, p. 189–198. doi: 10.1016/j.fsi.2017.06.015. Full text in Research Archive Show summary

  Infections caused by the facultative intracellular bacterial pathogen Piscirickettsia salmonis remains an unsolved problem for the aquaculture as no efficient treatments have been developed. As a result, substantial amounts of antibiotic have been used to limit salmonid rickettsial septicemia (SRS) disease outbreaks. The antibiotic usage has not reduced the occurrence, but lead to an increase in resistant strains, underlining the need for new treatment strategies. P. salmonis produce membrane vesicles (MVs); small spherical structures know to contain a variety of bacterial components, including proteins, lipopolysaccharides (LPS), DNA and RNA. MVs mimics' in many aspects their mother cell, and has been reported as alternative vaccine candidates. Here, MVs from P. salmonis was isolated and evaluated as a vaccine candidate against SRS in an adult zebrafish infection model. When zebrafish was immunized with MVs they were protected from subsequent challenge with a lethal dose of P. salmonis. Histological analysis showed a reduced bacterial load upon challenge in the MV immunized group, and the mRNA expression levels of several immune related genes altered, including mpeg1.1, tnfa, il1b, il10 and il6. The MVs induced the secretion of IgM upon immunization, indicating an immunogenic effect of the vesicles. Taken together, the data demonstrate a vaccine potential of MVs against P. salmonis.

• Griffiths, Gareth Wyn; Müller, Ferenc; Ledin, Johan; Patton, E. Elizabeth; Gjøen, Tor & Lobert, Viola [Show all 12 contributors for this article] (2016). Fish from Head to Tail: The 9th European Zebrafish Meeting in Oslo. Zebrafish. ISSN 1545-8547. doi: 10.1089/zeb.2015.1212. Full text in Research Archive
• Tandberg, Julia Isabel; Rojas, Leidy Ximena Lagos; Langlete, Petter; Berger, Eva Kathrin; Rishovd, Anne-Lise & Roos, Norbert [Show all 9 contributors for this article] (2016). Comparative Analysis of Membrane Vesicles from Three Piscirickettsia salmonis Isolates Reveals Differences in Vesicle Characteristics. PLOS ONE. 11. doi: 10.1371/journal.pone.0165099. Full text in Research Archive Show summary

  Membrane vesicles (MVs) are spherical particles naturally released from the membrane of Gram-negative bacteria. Bacterial MV production is associated with a range of phenotypes including biofilm formation, horizontal gene transfer, toxin delivery, modulation of host immune responses and virulence. This study reports comparative profiling of MVs from bacterial strains isolated from three widely disperse geographical areas. Mass spectrometry identified 119, 159 and 142 proteins in MVs from three different strains of Piscirickettsia salmonis isolated from salmonids in Chile (LF-89), Norway (NVI 5692) and Canada (NVI 5892), respectively. MV comparison revealed several strain-specific differences related to higher virulence capability for LF-89 MVs, both in vivo and in vitro, and stronger similarities between the NVI 5692 and NVI 5892 MV proteome. The MVs were similar in size and appearance as analyzed by electron microscopy and dynamic light scattering. The MVs from all three strains were internalized by both commercial and primary immune cell cultures, which suggest a potential role of the MVs in the bacterium’s utilization of leukocytes. When MVs were injected into an adult zebrafish infection model, an upregulation of several pro-inflammatory genes were observed in spleen and kidney, indicating a modulating effect on the immune system. The present study is the first comparative analysis of P. salmonis derived MVs, highlighting strain-specific vesicle characteristics. The results further illustrate that the MV proteome from one bacterial strain is not representative of all bacterial strains within one species.

• Lampe, Elisabeth Opsjøn; Brenz, Yannick Pirmin; Herrmann, Lydia; Repnik, Urska; Griffiths, Gareth Wyn & Zingmark, Carl [Show all 9 contributors for this article] (2016). Dissection of Francisellahost cell interactions in Dictyostelium discoideum. Applied and Environmental Microbiology. ISSN 0099-2240. 82(5), p. 1586–1598. doi: 10.1128/AEM.02950-15. Full text in Research Archive
• Brudal, Espen; Lampe, Elisabeth Opsjøn; Reubsaet, Leon; Roos, Norbert; Hegna, Ida Kristin & Thrane, Ida Marie [Show all 8 contributors for this article] (2015). Vaccination with outer membrane vesicles from Francisella noatunensis reduces development of francisellosis in a zebrafish model. Fish and Shellfish Immunology. ISSN 1050-4648. 42(1), p. 50–57. doi: 10.1016/j.fsi.2014.10.025. Full text in Research Archive
• Brudal, Espen; Ulanova, Lilia; Lampe, Elisabeth Opsjøn; Rishovd, Anne-Lise; Griffiths, Gareth Wyn & Winther-Larsen, Hanne C. (2014). Establishment of Three Francisella Infections in Zebrafish Embryos at Different Temperatures. Infection and Immunity. ISSN 0019-9567. 82(6), p. 2180–2194. doi: 10.1128/IAI.00077-14. Full text in Research Archive
• Karlsen, Christian; Ellingsen, Anette Bauer; Wiik-Nielsen, Christer R.; Winther-Larsen, Hanne C.; Colquhoun, Duncan John & Sørum, Henning (2014). Host specificity and clade dependent distribution of putative virulence genes in Moritella viscosa. Microbial Pathogenesis. ISSN 0882-4010. 77, p. 53–65. doi: 10.1016/j.micpath.2014.09.014. Full text in Research Archive Show summary

  Moritella viscosa is the aetiological agent of winter-ulcer disease in farmed salmonids in the North Atlantic. Previously, two major (typical and variant) genetic clades have been demonstrated within this bacterial species, one of which is almost solely related to disease in Atlantic salmon (Salmo salar). In the present study infection trials demonstrated that ‘typical’ M. viscosa isolated from Norwegian Atlantic salmon was highly virulent in this fish species but resulted in lower levels of mortality in rainbow trout. ‘Variant’ M. viscosa isolated from rainbow trout resulted in modest mortality levels in both Atlantic salmon and rainbow trout. To investigate the possible genetic background for inter-strain virulence differences, 38 M. viscosa isolates of diverse geographical origin and host species and a number of other Moritella spp. were investigated for the presence/absence of putative virulence related homologs. All isolates were positive for DNA sequences coding for; the Type VI secretion ATPase (clpV), hemolysin co-regulated protein (hcp), bacterioferritins (bfrA and bfrB), lectin (hemG), phospholipase D (pld), multifunctional autoprocessing repeats-in-toxin (martxA), aerolysin (aer), invasin (inv), and cytotoxic necrotizing factor (cnf), with the exception of one isolate in which cnf could not be confirmed. The product of an ABC transporter metal-binding lipoprotein (mat) was consistently detected although 11 isolates, all phylogenetically related, appear to produce a truncated version. A putative insecticidal toxin complex (mitABC) was detected almost exclusively in ‘typical’ Atlantic salmon isolates, and our data indicate that this complex of genes is expressed and co-transcribed. Transmission electron microscopy investigation revealed pili and flagella surface structures on nine M. viscosa representing both typical and variant isolates. Our results provide strong support for the existence of host specificity/high virulence in ‘typical’ M. viscosa related to Atlantic salmon. The gene distribution also provides further support for the genetic division within M. viscosa, and constitutes a basis for further study of the importance of the mitABC complex in winter-ulcer pathogenesis.

• Vestvik, Nils Fredrik; Rønneseth, Anita; Kalgraff, Cathrine Anette Kanikeberg; Winther-Larsen, Hanne Cecilie; Wergeland, Heidrun Inger & Haugland, Gyri Teien (2013). Francisella noatunensis subsp noatunensis replicates within Atlantic cod (Gadus morhua L.) leucocytes and inhibits respiratory burst activity. Fish and Shellfish Immunology. ISSN 1050-4648. 35(3), p. 725–733. doi: 10.1016/j.fsi.2013.06.002. Full text in Research Archive
• Brudal, Espen; Winther-Larsen, Hanne Cecilie; Colquhoun, Duncan John & Duodu, Samuel (2013). Evaluation of reference genes for reverse transcription quantitative PCR analyses of fish-pathogenic Francisella strains exposed to different growth conditions. BMC Research Notes. 6. doi: 10.1186/1756-0500-6-76. Full text in Research Archive Show summary

  Background Reverse transcription quantitative PCR has become a powerful technique to monitor mRNA transcription in response to different environmental conditions in many bacterial species. However, correct evaluation of data requires accurate and reliable use of reference genes whose transcription does not change during the course of the experiment. In the present study exposure to different growth conditions was used to validate the transcription stability of eight reference gene candidates in three strains from two subspecies of Francisella noatunensis, a pathogen causing disease in both warm and cold water fish species. Results Relative transcription levels for genes encoding DNA gyrase (gyrA), RNA polymerase beta subunit (rpoB), DNA polymerase I (polA), cell division protein (ftsZ), outer membrane protein (fopA), riboflavin biosynthesis protein (ribC), 16S ribosomal RNA (16S rRNA) and DNA helicases (uvrD) were quantified under exponential, stationary and iron-restricted growth conditions. The suitability of selected reference genes for reliable interpretation of gene expression data was tested using the virulence-associated intracellular growth locus subunit C (iglC) gene. Conclusion Although the transcription stability of the reference genes was slightly different in the three strains studied, fopA, ftsZ and polA proved to be the most stable and suitable for normalization of gene transcription in Francisella noatunensis ssp.

• Bjelland, Ane Mohn; Johansen, Renate; Brudal, Espen; Hansen, Hilde; Winther-Larsen, Hanne Cecilie & Sørum, Henning (2012). Vibrio salmonicida pathogenesis analyzed by experimental challenge of Atlantic salmon (Salmo salar). Microbial Pathogenesis. ISSN 0882-4010. 52(1), p. 77–84. doi: 10.1016/j.micpath.2011.10.007. Full text in Research Archive
• Bjelland, Ane Mohn; Sørum, Henning; Tegegne, Daget Ayana; Winther-Larsen, Hanne Cecilie; Willassen, Nils Peder & Hansen, Hilde (2012). LitR of Vibrio salmonicida Is a Salinity-Sensitive Quorum-Sensing Regulator of Phenotypes Involved in Host Interactions and Virulence. Infection and Immunity. ISSN 0019-9567. 80(5), p. 1681–1689. doi: 10.1128/IAI.06038-11. Full text in Research Archive
• Ford, Christopher G.; Kolappan, Subramaniapillai; Phan, Hanh Thi Hieu; Waldor, Matthew K.; Winther-Larsen, Hanne Cecilie & Craig, Lisa (2012). Crystal Structures of a CTX phi pIII Domain Unbound and in Complex with a Vibrio cholerae TolA Domain Reveal Novel Interaction Interfaces. Journal of Biological Chemistry. ISSN 0021-9258. 287(43), p. 36258–36272. doi: 10.1074/jbc.M112.403386. Full text in Research Archive
• Bakkemo, Kathrine Ryvold; Mikkelsen, Helene; Bordevik, Marianne; Torgersen, Jacob; Winther-Larsen, Hanne Cecilie & Vanberg, Christin [Show all 9 contributors for this article] (2011). Intracellular localisation and innate immune responses following Francisella noatunensis infection of Atlantic cod (Gadus morhua) macrophages. Fish and Shellfish Immunology. ISSN 1050-4648. 31, p. 993–1004. doi: 10.1016/j.fsi.2011.08.020. Full text in Research Archive
• Jacobsen, Wolfgang Mathias; Salomonsson, Emelie; Aas, Finn Erik; Forslund, Anna-Lena; Winther-Larsen, Hanne Cecilie & Maier, Josef [Show all 14 contributors for this article] (2011). O-Linked Glycosylation of the PilA Pilin Protein of Francisella tularensis: Identification of the Endogenous Protein-Targeting Oligosaccharyltransferase and Characterization of the Native Oligosaccharide. Journal of Bacteriology. ISSN 0021-9193. 193(19), p. 5487–5497. doi: 10.1128/JB.00383-11. Full text in Research Archive
• Børud, Bente; Aas, Finn Erik; Vik, Åshild; Winther-Larsen, Hanne Cecilie; Jacobsen, Wolfgang Mathias & Koomey, Michael (2010). Genetic, Structural, and Antigenic Analyses of Glycan Diversity in the O-Linked Protein Glycosylation Systems of Human Neisseria Species. Journal of Bacteriology. ISSN 0021-9193. 192(11), p. 2816–2829. doi: 10.1128/JB.00101-10. Full text in Research Archive
• Heiniger, Ryan W; Winther-Larsen, Hanne Cecilie; Raymond, Pickles; Koomey, Michael & Wolfgang, Matthew (2010). Infection of human mucosal tissue by Pseudomonas aeruginosa requires sequential and mutually dependent virulence factors and a novel pilus-associated adhesin. Cellular Microbiology. ISSN 1462-5814. 12(8), p. 1158–1173. doi: 10.1111/j.1462-5822.2010.01461.x. Full text in Research Archive
• Salomonsson, Emelie; Forsberg, A; Roos, Norbert; Holz, C; Maier, B & Koomey, Michael [Show all 7 contributors for this article] (2009). Functional analyses of pilin-like proteins from Francisella tularensis: complementation of type IV pilus phenotypes in Neisseria gonorrhoeae. Microbiology (Reading). ISSN 1350-0872. 155, p. 2546–2559. doi: 10.1099/mic.0.028183-0. Full text in Research Archive
• Næssan, Cecilia L; Jacobsen, Wolfgang Mathias; Heiniger, Ryan W; Wolfgang, Matthew; Aas, Finn Erik & Røhr, Åsmund Kjendseth [Show all 8 contributors for this article] (2008). Genetic and functional analyses of PptA, a phospho-form transferase targeting type IV pili in Neisseria gonorrhoeae. Journal of Bacteriology. ISSN 0021-9193. 190(1), p. 387–400. doi: 10.1128/JB.00765-07. Full text in Research Archive
• Winther-Larsen, Hanne C; Wolfgang, Matthew; Putten, JPM van; Roos, Norbert; Aas, Finn Erik & Jacobsen, Wolfgang Mathias [Show all 8 contributors for this article] (2007). Pseudomonas aeruginosa type IV pilus expression in Neisseria gonorrhoeae: Effects of pilin subunit composition on function and organelle dynamics. Journal of Bacteriology. ISSN 0021-9193. 189(18), p. 6676–6685. doi: 10.1128/JB.00407-07. Full text in Research Archive
• Aas, Finn Erik; Winther-Larsen, Hanne C; Wolfgang, Matthew; Frye, Stephan; Løvold, Cecilia & Roos, Norbert [Show all 8 contributors for this article] (2007). Substitutions in the N-terminal alpha helical spine of Neisseria gonorrhoeae pilin affect type IV pilus assembly, dynamics and associated functions. Molecular Microbiology. ISSN 0950-382X. 63, p. 69–85. doi: 10.1111/j.1365-2958.2006.05482.x. Full text in Research Archive
• Aas, Finn Erik; Winther-Larsen, Hanne C; Wolfgang, Matthew; Frye, Stephan Alfons; Løvold, Cecilia & Roos, Norbert [Show all 8 contributors for this article] (2006). Substitutions in the N-terminal alpha helical spine of Neisseria gonorrhoeae pilin affects Type IV pilus assembly, dynamics and associated functions. Molecular Microbiology. ISSN 0950-382X. 63(1), p. 69–85. Full text in Research Archive

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• Alestrøm, Peter & Winther-Larsen, Hanne Cecilie (2016). Zebrafish offer aquaculture its services. Chapter 8 of Genomics in aquaculture. Elsevier. ISBN 9780128014189. 30 p. Full text in Research Archive

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• Winther-Larsen, Hanne Cecilie; Mertes, Verena; Linke, Dirk; Saragliadis, Athanasios; Roos, Norbert & Mascherin, Elisa [Show all 7 contributors for this article] (2024). Recombinant extracellular vesicles as vaccines within animal health. Full text in Research Archive Show summary

  Secretion of extracellular vesicles (EVs) from the bacterial body is associated with a range of phenotypes including cell-cell communication, host-pathogen interactions and antimicrobial resistance development. EV also elicit an immune response after immunization of a host making them an interesting vaccine candidate. We have investigated the use of EV as a potential vaccine against several bacterial pathogens creating problems in farmed animals including fish. Immunization with EV revealed protection against some diseases, but not in others where we hypothesized that the EV was part of the microbial pathogenesis. To circumvent possible negative side effects of natural EV, we have explored the recombinant EV (rEV) isolated from E. coli expressing antigens from other infectious agents. We have expressed antigens from the fish bacterial species Yersinia ruckeri in E. coli. The rEV was isolated using tangential flow and ultracentrifugation before analysis by transmission electron microscopy (TEM) and Nano-particle tracking analysis (NTA). The antigen expression was confirmed by SDS-PAGE and proteomics analysis. The rEVs did not elicit any toxicity when exposed to fish cells in culture. These results show that E. coli has the potential to be utilized as a vector for production of EVs expressing antigens from other bacterial species. These rEVs will hopefully circumvent the negative side effects of native EVs isolated from the pathogenic bacteria when used as vaccines and may enhance the repertoire of EVs based vaccines within animal health.

• Skogvoll, Vidar; Winther-Larsen, Hanne Cecilie & Robertsen, Ida (2024). Real læring - Realistfabrikken: Hvordan lage farmasøyt. [Radio]. Podcast. Full text in Research Archive
• Urtubia, Areli Moe; Winther-Larsen, Hanne Cecilie & Økstad, Ole Andreas (2023). Novel principles of drug resistance in the WHO priority 1 pathogen Acinetobacter baumannii. Full text in Research Archive
• Winther-Larsen, Hanne Cecilie (2023). Bacterial extracellular vesicles. Full text in Research Archive
• Mertes, Verena; Saragliadis, Athanasios; Mascherin, E; Antenucci, Fabio; Bojesen, Anders Miki & Colquhoun, Duncan John [Show all 8 contributors for this article] (2023). Characterization of bacterial extracellular vesicles A versatile tool for potential vaccine application in aquaculture. Full text in Research Archive
• Subramani, Saranya & Winther-Larsen, Hanne Cecilie (2023). Identification of Novel Vaccine Candidates against Piscirikettsiosis. Full text in Research Archive
• Mertes, Verena; Saragliadis, Athanasios; Ciani, Elia; Colquhoun, Duncan John; Linke, Dirk & Winther-Larsen, Hanne Cecilie (2023). Characterization of extracellular membrane vesicles secreted from the Gram-negative bacterial fish pathogen Yersinia ruckeri. Full text in Research Archive
• Winther-Larsen, Hanne Cecilie; Langlete, Petter & Krabberød, Anders Kristian (2023). Loading cargo and messenging by bacterial extracellular vesicles. Full text in Research Archive
• Hovd, Rebekka Rolfsnes; Rongved, Pål; Hovland, Ragnar; Kaupang, Åsmund; Frøhlich, Christopher & Huber, Sandra [Show all 8 contributors for this article] (2023). Investigating the Mechanism of Action of a Novel Dual β-Lactamase Inhibitor. Full text in Research Archive
• Hovd, Rebekka Rolfsnes; Rongved, Pål; Hovland, Ragnar; Kaupang, Åsmund; Frøhlich, Christopher & Huber, Sandra [Show all 8 contributors for this article] (2023). Investigating the Mechanism of Action of a New Novel Dual β-Lactamase Inhibitor. Full text in Research Archive
• Mertes, Verena; Saragliadis, Athanasios; Attenucci, Fabio; Wrobel, Agnieszka; Ciani, Elia & Linke, Dirk [Show all 8 contributors for this article] (2022). Characterization of bacterial extracellular vesicles from a fish pathogen, their role in virulence and possible function as vaccine in aquaculture. Full text in Research Archive
• Hovd, Rebekka Rolfsnes; Rongved, Pål; Klem, Bjørn; Hovland, Ragnar; Kaupang, Åsmund & Økstad, Ole Andreas Løchen [Show all 7 contributors for this article] (2022). Bacterial antimicrobial resistance mechanisms - The novel dual serine- and metallo-β-lactamase inhibitor APC247. Full text in Research Archive
• Hovd, Rebekka Rolfsnes; Rongved, Pål; Klem, Bjørn; Hovland, Ragnar; Kildahl-Andersen, Geir & Kaupang, Åsmund [Show all 8 contributors for this article] (2022). The novel antimicrobial resistance breaker APC247 – a putative dual serine- and metallo-β-lactamase inhibitor. Full text in Research Archive
• Mertes, Verena; Saragliadis, Athanasios; Ciani, Elia; Linke, Dirk; Colquhoun, Duncan J & Winther-Larsen, Hanne Cecilie (2021). Characterization of membrane vesicles from fish pathogens, their role in virulence and possible function as a vaccine in aquaculture. Full text in Research Archive
• Linke, Dirk; Økstad, Ole Andreas; Haugen, Håvard Jostein & Winther-Larsen, Hanne Cecilie (2021). The exchange program MISC - Options for internships at the University of Oslo (with descriptions of current projects). Full text in Research Archive
• Tandberg, Julia Isabel; Lagos, Leidy; Kashulin, Alexander; Sørum, Henning & Winther-Larsen, Hanne Cecilie (2019). Bacterial membrane vesicles as vaccines in aquaculture. Full text in Research Archive
• Tandberg, Julia Isabel; Lagos, Leidy; Kashulin, Alexander; Langlete, Petter & Winther-Larsen, Hanne Cecilie (2019). Bacterial membrane vesicles as vaccines in aquaculture. Full text in Research Archive
• Vogel, Anne Ilse Maria; Winther-Larsen, Hanne Cecilie; Roos, Norbert; Lale, Rahmi & Hohmann-Marriott, Martin Frank (2018). Function of type IV pili in iron acquisition in Synechococcus sp. PCC 7002. Full text in Research Archive
• Vogel, Anne Ilse Maria; Winther-Larsen, Hanne Cecilie; Roos, Norbert; Lale, Rahmi & Hohmann-Marriott, Martin Frank (2018). Function of type IV pili in iron acquisition in Synechococcus sp. PCC 7002. Full text in Research Archive
• Vogel, Anne Ilse Maria; Winther-Larsen, Hanne Cecilie; Roos, Norbert; Lale, Rahmi & Hohmann-Marriott, Martin Frank (2018). Function of type IV pili in iron acquisition in Synechococcus sp. PCC 7002. Full text in Research Archive
• Vogel, Anne Ilse Maria; Winther-Larsen, Hanne Cecilie; Roos, Norbert; Lale, Rahmi & Hohmann-Marriott, Martin Frank (2018). A novel function of type IV pili in iron uptake in Synechococcus sp. PCC 7002. Full text in Research Archive Show summary

  Iron is abundant in the Earth’s crust, but in marine environments, iron is often the limiting micronutrient for cyanobacterial growth. Marine cyanobacteria such as Synechococcus sp. PCC 7002 (hereafter Synechococcus) require iron for their photosynthetic machinery, especially Photosystem I, and have therefore developed efficient iron acquisition strategies. Recent research on type IV pili suggests that these so-called “nanowires” can increase metal bioavailability by facilitating reduction of extracellular electron acceptors such as iron oxides (1,2). These pili consist of tightly stacked pilA1 proteins and seem to have conductive properties (1). We deleted the gene encoding pilA1 in Synechococcus and studied the growth of the deletion strain on different iron minerals with varying bioavailability. The ΔpilA1 strain shows reduced growth compared to wildtype Synechococcus when grown on iron oxides with low bioavailability. We analyzed pili expression with SEM, TEM and mass spectrometry. Our results indicate a clear effect of pilA1 deletion on the expression of alternative pilins. Finally, we assessed the state of the photosynthetic complexes by spectroscopic methods. Spectral analysis of the ΔpilA1 strain indicate changes of the photosynthetic complexes consistent with iron stress. Our results indicate a novel function of type IV pili in iron acquisition in marine cyanobacteria. Heterologous pilA expression and deletion of genes involved in other parts of the external electron transport chain will further elucidate how intracellular electron transport is coupled to extracellular reduction. (1) Gorby YA, Yanina S, McLean JS, et al (2006) Electrically conductive bacterial nanowires produced by Shewanella oneidensis strain MR-1 and other microorganisms. Proc Natl Acad Sci U S A 103:11358–63. doi: 10.1073/pnas.0604517103 (2) Lamb JJ, Hill RE, Eaton-Rye JJ, Hohmann-Marriott MF (2014) Functional role of PilA in iron acquisition in the cyanobacterium Synechocystis sp. PCC 6803. PLoS One 9:e105761. doi: 10.1371/journal.pone.0105761

• Winther-Larsen, Hanne Cecilie (2018). Bacterial membrane vesicles: Implication in aquaculture. Full text in Research Archive
• Lampe, Elisabeth Opsjøn; Brudal, Espen; Tandberg, Julia Isabel; Lagos, Leidy; Sjöstedt, Anders & Griffiths, Gareth Wyn [Show all 7 contributors for this article] (2018). Use of Zebrafish as Vaccine and Infection Model for Francisella. Full text in Research Archive
• Winther-Larsen, Hanne Cecilie (2018). Bacterial Membrane Vesicles in Therapeutics. Full text in Research Archive
• Winther-Larsen, Hanne Cecilie (2018). Bacterial membrane vesicles: Implication in aquaculture. Full text in Research Archive
• Vogel, Anne Ilse Maria; Winther-Larsen, Hanne Cecilie; Roos, Norbert; Lale, Rahmi & Hohmann-Marriott, Martin Frank (2018). Conductive Type IV pili play an important role for iron acquisition in the marine cyanobacterium Synechococcus sp. PCC 7002. Full text in Research Archive
• Griffiths, Gareth Wyn; Müller, Ference; Ledin, Johan; Patton, E. Elizabeth; Gjøen, Tor & Lobert, Viola [Show all 12 contributors for this article] (2016). Fish from Head to Tail: The 9th European Zebrafish Meeting in Oslo. Zebrafish. ISSN 1545-8547. 13(2), p. 132–137. doi: 10.1089/zeb.2015.1212. Full text in Research Archive
• Brudal, Espen; Isabel, Tandberg Julia; Sørum, Henning; Alexander, Kashulin & Winther-Larsen, Hanne C. (2015). Isolerte membranvesikler som vaksine mot francisellose og piscirickettsiose. Full text in Research Archive
• Brudal, Espen; Lampe, Elisabeth Opsjøn; Tandberg, Julia Isabel; Ulanova, Lilia; Winther-Larsen, Hanne Cecilie & Griffiths, Gareth Wyn (2015). Use of zebrafish as infection modell in aquaculture. Full text in Research Archive
• O., Lampe Elisabeth; Herrmann, Lydia; Brenz, Yannick Pirmin; Zingmark, Carl; Sjöstedt, Anders & Winther-Larsen, Hanne C. [Show all 7 contributors for this article] (2014). Dissection of Francisella virulence in Dictyostelium; a genetically tractable host system. Full text in Research Archive
• Karlsen, Christian; Ellingsen, Anetter Bauer; Wiik-Nielsen, Christer R.; Winther-Larsen, Hanne C.; J., Colquhoun Duncan & Sørum, Henning (2014). Distribusjon av virulensfaktorer og verts spesifisitet hos Moritella viscosa. Full text in Research Archive
• Winther-Larsen, Hanne C. (2014). Bakterier og virus. [Radio]. NRK. Full text in Research Archive
• Brudal, Espen; Milton, Debra L; myrtennäs, Kerstin; Roos, Norbert; Griffiths, Gareth Wyn & Winther-Larsen, Hanne C. (2014). A degenerative Type IV pilus like system is functional and required for virulence in the fish pathogen Francisella noatunensis subsp. noatunensis. Full text in Research Archive
• Lampe, Elisabeth Opsjøn; Zingmark, C.; Hemnann, L.; Brudal, Espen; Rishovd, Anne-Lise & Broms, J. [Show all 10 contributors for this article] (2013). A study of virulence factors in the fish pathogen F. noatunensis ssp noatunensis. Fish and Shellfish Immunology. ISSN 1050-4648. 34(6), p. 1716–1716. Full text in Research Archive
• Winther-Larsen, Hanne Cecilie (2010). Bio warfare research: help to find a remedy against francisellosis in fish? Full text in Research Archive
• Winther-Larsen, Hanne Cecilie; Vanberg, Christin & Sørum, Henning (2010). Francisellosis - AFISH business. Full text in Research Archive
• Winther-Larsen, Hanne Cecilie; Vanberg, Christin & Sørum, Henning (2009). Bioterrorisme-forskning bidrar til å løse Francisella problemet i torskeoppdrett. Full text in Research Archive
• Salomonsson, Emelie; Forsberg, A; Roos, Norbert; Holz, C; Maier, B. & Koomey, Michael [Show all 7 contributors for this article] (2009). Heterologous expression of Francisella tularensis type IV pili genes in Neisseria gonorrhoeae confirms that PilA can form functional pili. Full text in Research Archive
• Salomonsson, Emelie; Winther-Larsen, Hanne Cecilie; Holz, Claudia; Maier, Berenike; Koomey, Michael & Forsberg, Åke (2008). Expressing Type IV pilin-like genes from Francisella tularensis in Neisseria gonorrhoeae. Full text in Research Archive
• Salomonsson, Emelie; Koomey, Michael; Roos, Norbert; Forsberg, Åke & Winther-Larsen, Hanne C (2007). Knowledge about the bioterrorism class A agent Francisella tularensis by utilizing Neisseria gonorrhoeae. Full text in Research Archive
• Salomonsson, Emelie; Koomey, Michael; Roos, Norbert; Forsberg, Åke & Winther-Larsen, Hanne C (2007). Exploring the role of virulence-associated pilin proteins from Francisella tularensis using heterologous expression in Neisseria. Full text in Research Archive
• Winther-Larsen, Hanne C; Heiniger, Ryan; Roos, Norbert; Putten, JPM van; Koomey, Michael & Wolfgang, Matthew (2006). Dynamics of Type IV pilus biogenesis in Pseudomonas aeruginosa. Full text in Research Archive
• Salomonsson, Emelie; Forsberg, Åke; Koomey, Michael & Winther-Larsen, Hanne C (2006). Heterologous expression of Francisella pilin genes in Neisseria gonorrhoeae. Full text in Research Archive Show summary

  Analysis of the genome sequence of F. tularensis subsp. tularensis strain SCHU S4 has identified gene clusters encoding proteins postulated to be involved in protein secretion or in type IV pili (Tfp) expression. SCHU S4 encodes at least six putative pilin genes. We have recently verified that one of these genes, denoted pilA, is essential for full virulence in a mouse infection model. However, so far we have been unable to verify that F. tularensis expresses Tfp.or secreton related organelles To establish if any of the six pilin genes could form a pilus we expressed them, and in addition the pilA gene of subsp. novicida, in N. gonorrhoeae Western blot analysis verified that all pilins except one were expressed in this background. Expression of pilin filaments was analysed by immunofluorescence and electron microscopy and only PilA of F. novicida and SCHU S4 produced Tfp-like filaments. In support of PilA from F. novicida to form pilus-like multimers was that its expression also resulted in restored competence for DNA uptake in N. gonorrhoeae. However, at this point we cannot exclude that additional pilins are part of or can also form Tfp or a protein secretion related pseudopilus.

• Winther-Larsen, Hanne C; Løvold, Cecilia; Wolfgang, Matthew; Putten, JPM van; Roos, Norbert & Aas, Finn Erik [Show all 10 contributors for this article] (2006). Microbial hair-extention. Full text in Research Archive
• Winther-Larsen, Hanne C; Heiniger, Ryan W; Roos, Norbert; Egge-Jacobsen, Wolfgang; Putten, JPM van & Koomey, Michael [Show all 7 contributors for this article] (2006). Dynamics of Type IV pili Biogenesis in Pseudomonas aeruginosa. Full text in Research Archive

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