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Mollerup IM, Bjørneset J, Krock B, Jensen TH, Galatius A, Dietz R, Teilmann J, van den Brand JMA, Osterhaus A, Kokotovic B, Lundholm N, Olsen MT. Did algal toxin and Klebsiella infections cause the unexplained 2007 mass mortality event in Danish and Swedish marine mammals? Sci Total Environ 2024; 914:169817. [PMID: 38184244 DOI: 10.1016/j.scitotenv.2023.169817] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 12/21/2023] [Accepted: 12/29/2023] [Indexed: 01/08/2024]
Abstract
An unusual mass mortality event (MME) of harbour seals (Phoca vitulina) and harbour porpoises (Phocoena phocoena) occurred in Denmark and Sweden in June 2007. Prior to this incident, the region had experienced two MMEs in harbour seals caused by Phocine Distemper Virus (PDV) in 1988 and 2002. Although epidemiology and symptoms of the 2007 MME resembled PDV, none of the animals examined for PDV tested positive. Thus, it has been speculated that another - yet unknown - pathogen caused the June 2007 MME. To shed new light on the likely cause of death, we combine previously unpublished veterinary examinations of harbour seals with novel analyses of algal toxins and algal monitoring data. All harbour seals subject to pathological examination showed pneumonia, but were negative for PDV, influenza and coronavirus. Histological analyses revealed septicaemia in multiple animals, and six animals tested positive for Klebsiella pneumonia. Furthermore, we detected the algal Dinophysis toxin DTX-1b (1-115 ng g-1) in five seals subject to toxicology, representing the first time DTX-1b has been detected in marine vertebrates. However, no animals tested positive for both Klebsiella and toxins. Thus, while our relatively small sample size prevent firm conclusions on causative agents, we speculate that the unexplained MME may have been caused by a chance incidence of multiple pathogens acting in parallel in June 2007, including Dinophysis toxin and Klebsiella. Our study illustrates the complexity of wildlife MMEs and highlights the need for thorough sampling during and after MMEs, as well as additional research on and monitoring of DTX-1b and other algal toxins in the region.
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Affiliation(s)
- Ida-Marie Mollerup
- Natural History Museum of Denmark, University of Copenhagen, Øster Farimagsgade 5, 1353 Copenhagen K, Denmark; Section for Molecular Ecology and Evolution, Globe Institute, University of Copenhagen, Øster Farimagsgade 5, 1353 Copenhagen K, Denmark
| | - Juni Bjørneset
- Natural History Museum of Denmark, University of Copenhagen, Øster Farimagsgade 5, 1353 Copenhagen K, Denmark; Section for Molecular Ecology and Evolution, Globe Institute, University of Copenhagen, Øster Farimagsgade 5, 1353 Copenhagen K, Denmark
| | - Bernd Krock
- Alfred Wegener Institut-Helmholtz Zentrum für Polar- und Meeresforschung, Am Handelshafen 12, D-27570 Bremerhaven, Germany
| | - Trine Hammer Jensen
- Aalborg Zoo/Section of Biology and Environmental Science, University of Aalborg, Fredrik Bajers Vej 7, H, 9220 Aalborg, Denmark
| | - Anders Galatius
- Section for Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Rune Dietz
- Section for Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | - Jonas Teilmann
- Section for Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark
| | | | - Albert Osterhaus
- Research Center Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine, Bünteweg 17, 30559 Hannover, Germany
| | - Branko Kokotovic
- Reference Laboratory for Antimicrobial Resistance, Department of Bacteria, Parasites & Fungi, Statens Seruminstitut, Artillerivej 5, 2300 Copenhagen S, Denmark
| | - Nina Lundholm
- Natural History Museum of Denmark, University of Copenhagen, Øster Farimagsgade 5, 1353 Copenhagen K, Denmark.
| | - Morten Tange Olsen
- Section for Molecular Ecology and Evolution, Globe Institute, University of Copenhagen, Øster Farimagsgade 5, 1353 Copenhagen K, Denmark; Section for Marine Mammal Research, Department of Bioscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
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Shin DL, Siebert U, Haas L, Valentin-Weigand P, Herrler G, Wu NH. Primary harbor seal (Phoca vitulina) airway epithelial cells show high susceptibility to infection by a seal-derived influenza A virus (H5N8). Transbound Emerg Dis 2022; 69:e2378-e2388. [PMID: 35504691 DOI: 10.1111/tbed.14580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/24/2022] [Accepted: 04/29/2022] [Indexed: 11/29/2022]
Abstract
Highly pathogenic avian influenza viruses of the H5N8 subtype have been circulating in Europe and Asia since 2016, causing huge economic losses to the poultry industry. A new wave of H5Nx infections has begun in 2020. The viruses mainly infect wild birds and waterfowl; from there they spread to poultry and cause disease. Previous studies have shown that the H5N8 viruses have seldom spread to mammals; however, reports in early 2021 indicate that humans may be infected, and some incident reports indicate that H5Nx clade 2.3.4.4B virus may be transmitted to wild mammals, such as red foxes and seals. In order to get more information on how the H5N8 virus affects seals and other marine animals, here, we used primary cultures to analyze the cell tropism of the H5N8 virus, which was isolated from an infected gray seal (H5N8/Seal-2016). Primary tracheal epithelial cells were readily infected by H5N8/Seal -2016 virus; in contrast, the commonly used primary seal kidney cells required the presence of exogenous trypsin to initiate virus infection. When applied to an ex vivo precision-cut lung slice model, compared with recombinant human H3N2 virus or H9N2 LPAI virus, the H5N8/Seal-2016 virus replicated to a high titer and caused a strong detrimental effect; with these characteristics, the virus was superior to a human H3N2 virus and to an H9N2 LPAI virus. By using well-differentiated air-liquid interface cultures, we have observed that ALI cultures of canines, ferrets, and harbor seals are more sensitive to H5N8/Seal-2016 virus than are human or porcine ALI cultures, which cannot be fully explained by sialic acid distribution. Our results indicate that the airway epithelium of carnivores may be the main target of H5N8 viruses. Consideration should be given to an increased monitoring of the distribution of highly pathogenic avian influenza viruses in wild animals. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Dai-Lun Shin
- Institute of Virology, Department of Infectious Diseases, University of Veterinary Medicine Hannover, Hannover, Germany.,Research Center for Emerging Infections and Zoonoses, Hannover, Germany
| | - Ursula Siebert
- Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Ludwig Haas
- Institute of Virology, Department of Infectious Diseases, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Peter Valentin-Weigand
- Institute of Microbiology, Department of Infectious Diseases, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Georg Herrler
- Institute of Virology, Department of Infectious Diseases, University of Veterinary Medicine Hannover, Hannover, Germany
| | - Nai-Huei Wu
- Department of Veterinary Medicine, National Taiwan University, Taiwan
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Claus-desbonnet H, Nikly E, Nalbantova V, Karcheva-bahchevanska D, Ivanova S, Pierre G, Benbassat N, Katsarov P, Michaud P, Lukova P, Delattre C. Polysaccharides and Тheir Derivatives as Potential Antiviral Molecules. Viruses 2022; 14:426. [PMID: 35216019 PMCID: PMC8879384 DOI: 10.3390/v14020426] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 02/08/2022] [Accepted: 02/16/2022] [Indexed: 01/27/2023] Open
Abstract
In the current context of the COVID-19 pandemic, it appears that our scientific resources and the medical community are not sufficiently developed to combat rapid viral spread all over the world. A number of viruses causing epidemics have already disseminated across the world in the last few years, such as the dengue or chinkungunya virus, the Ebola virus, and other coronavirus families such as Middle East respiratory syndrome (MERS-CoV) and severe acute respiratory syndrome (SARS-CoV). The outbreaks of these infectious diseases have demonstrated the difficulty of treating an epidemic before the creation of vaccine. Different antiviral drugs already exist. However, several of them cause side effects or have lost their efficiency because of virus mutations. It is essential to develop new antiviral strategies, but ones that rely on more natural compounds to decrease the secondary effects. Polysaccharides, which have come to be known in recent years for their medicinal properties, including antiviral activities, are an excellent alternative. They are essential for the metabolism of plants, microorganisms, and animals, and are directly extractible. Polysaccharides have attracted more and more attention due to their therapeutic properties, low toxicity, and availability, and seem to be attractive candidates as antiviral drugs of tomorrow.
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