Novel Divergent Polar Bear-Associated Mastadenovirus Recovered from a Deceased Juvenile Polar Bear

ABSTRACT Polar bears in captivity can be exposed to opportunistic pathogens not present in their natural environments. A 4-month-old polar bear (Ursus maritimus) living in an isolated enclosure with his mother in the Tierpark Berlin, Berlin, Germany, was suffering from severe abdominal pain, mild di...

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Autores principales:	Anisha Dayaram, Kyriakos Tsangaras, Selvaraj Pavulraj, Walid Azab, Nicole Groenke, Gudrun Wibbelt, Florian Sicks, Nikolaus Osterrieder, Alex D. Greenwood
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2018
Materias:	adeno-associated virus evolutionary biology novel virus phylogenetic analysis polar bear Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/4a29ec5b31974a29b9b04352edaa8b3b
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spelling	oai:doaj.org-article:4a29ec5b31974a29b9b04352edaa8b3b2021-11-15T15:25:50ZNovel Divergent Polar Bear-Associated Mastadenovirus Recovered from a Deceased Juvenile Polar Bear10.1128/mSphere.00171-182379-5042https://doaj.org/article/4a29ec5b31974a29b9b04352edaa8b3b2018-08-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mSphere.00171-18https://doaj.org/toc/2379-5042ABSTRACT Polar bears in captivity can be exposed to opportunistic pathogens not present in their natural environments. A 4-month-old polar bear (Ursus maritimus) living in an isolated enclosure with his mother in the Tierpark Berlin, Berlin, Germany, was suffering from severe abdominal pain, mild diarrhea, and loss of appetite and died in early 2017. Histopathology revealed severe hepatic degeneration and necrosis without evidence of inflammation or inclusion bodies, although a viral infection had been suspected on the basis of the clinical signs. We searched for nucleic acids of pathogens by shotgun high-throughput sequencing (HTS) from genomic DNA and cDNA extracted from tissue and blood. We identified a novel Mastadenovirus and assembled a nearly complete genome from the shotgun sequences. Quantitative PCR (qPCR) revealed that viral DNA was present in various concentrations in all tissues examined and that the highest concentrations were found in blood. Viral culture did not yield cytopathic effects, but qPCR suggested that virus replication was sustained for up to three passages. Positive immunofluorescence staining confirmed that the virus was able to replicate in the cells during early passage. Phylogenetic analysis demonstrated that the virus is highly divergent compared to other previously identified Mastadenovirus members and basal to most known viral clades. The virus was found only in the 4-month-old bear and not in other captive polar bears tested. We surmised, therefore, that the polar bear was infected from an unknown reservoir, illustrating that adenoviral diversity remains underestimated and that cross-species transmission of viruses can occur even under conditions of relative isolation. IMPORTANCE Cross-species transmission of viral pathogens is becoming an increasing problem for captive-animal facilities. This study highlights how animals in captivity are vulnerable to novel opportunistic pathogens, many of which do not result in straightforward diagnosis from symptoms and histopathology. In this study, a novel pathogen was suspected to have contributed to the death of a juvenile polar bear. HTS techniques were employed, and a novel Mastadenovirus was isolated. The virus was present in both the tissue and blood samples. Phylogenetic analysis of the virus at both the gene and genome levels revealed that it is highly divergent to other known mastadenoviruses. Overall, this study shows that animals in isolated conditions still come into contact with novel pathogens, and for many of these pathogens, the host reservoir and mode of transmission are yet to be determined.Anisha DayaramKyriakos TsangarasSelvaraj PavulrajWalid AzabNicole GroenkeGudrun WibbeltFlorian SicksNikolaus OsterriederAlex D. GreenwoodAmerican Society for Microbiologyarticleadeno-associated virusevolutionary biologynovel virusphylogenetic analysispolar bearMicrobiologyQR1-502ENmSphere, Vol 3, Iss 4 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	adeno-associated virus evolutionary biology novel virus phylogenetic analysis polar bear Microbiology QR1-502
spellingShingle	adeno-associated virus evolutionary biology novel virus phylogenetic analysis polar bear Microbiology QR1-502 Anisha Dayaram Kyriakos Tsangaras Selvaraj Pavulraj Walid Azab Nicole Groenke Gudrun Wibbelt Florian Sicks Nikolaus Osterrieder Alex D. Greenwood Novel Divergent Polar Bear-Associated Mastadenovirus Recovered from a Deceased Juvenile Polar Bear
description	ABSTRACT Polar bears in captivity can be exposed to opportunistic pathogens not present in their natural environments. A 4-month-old polar bear (Ursus maritimus) living in an isolated enclosure with his mother in the Tierpark Berlin, Berlin, Germany, was suffering from severe abdominal pain, mild diarrhea, and loss of appetite and died in early 2017. Histopathology revealed severe hepatic degeneration and necrosis without evidence of inflammation or inclusion bodies, although a viral infection had been suspected on the basis of the clinical signs. We searched for nucleic acids of pathogens by shotgun high-throughput sequencing (HTS) from genomic DNA and cDNA extracted from tissue and blood. We identified a novel Mastadenovirus and assembled a nearly complete genome from the shotgun sequences. Quantitative PCR (qPCR) revealed that viral DNA was present in various concentrations in all tissues examined and that the highest concentrations were found in blood. Viral culture did not yield cytopathic effects, but qPCR suggested that virus replication was sustained for up to three passages. Positive immunofluorescence staining confirmed that the virus was able to replicate in the cells during early passage. Phylogenetic analysis demonstrated that the virus is highly divergent compared to other previously identified Mastadenovirus members and basal to most known viral clades. The virus was found only in the 4-month-old bear and not in other captive polar bears tested. We surmised, therefore, that the polar bear was infected from an unknown reservoir, illustrating that adenoviral diversity remains underestimated and that cross-species transmission of viruses can occur even under conditions of relative isolation. IMPORTANCE Cross-species transmission of viral pathogens is becoming an increasing problem for captive-animal facilities. This study highlights how animals in captivity are vulnerable to novel opportunistic pathogens, many of which do not result in straightforward diagnosis from symptoms and histopathology. In this study, a novel pathogen was suspected to have contributed to the death of a juvenile polar bear. HTS techniques were employed, and a novel Mastadenovirus was isolated. The virus was present in both the tissue and blood samples. Phylogenetic analysis of the virus at both the gene and genome levels revealed that it is highly divergent to other known mastadenoviruses. Overall, this study shows that animals in isolated conditions still come into contact with novel pathogens, and for many of these pathogens, the host reservoir and mode of transmission are yet to be determined.
format	article
author	Anisha Dayaram Kyriakos Tsangaras Selvaraj Pavulraj Walid Azab Nicole Groenke Gudrun Wibbelt Florian Sicks Nikolaus Osterrieder Alex D. Greenwood
author_facet	Anisha Dayaram Kyriakos Tsangaras Selvaraj Pavulraj Walid Azab Nicole Groenke Gudrun Wibbelt Florian Sicks Nikolaus Osterrieder Alex D. Greenwood
author_sort	Anisha Dayaram
title	Novel Divergent Polar Bear-Associated Mastadenovirus Recovered from a Deceased Juvenile Polar Bear
title_short	Novel Divergent Polar Bear-Associated Mastadenovirus Recovered from a Deceased Juvenile Polar Bear
title_full	Novel Divergent Polar Bear-Associated Mastadenovirus Recovered from a Deceased Juvenile Polar Bear
title_fullStr	Novel Divergent Polar Bear-Associated Mastadenovirus Recovered from a Deceased Juvenile Polar Bear
title_full_unstemmed	Novel Divergent Polar Bear-Associated Mastadenovirus Recovered from a Deceased Juvenile Polar Bear
title_sort	novel divergent polar bear-associated mastadenovirus recovered from a deceased juvenile polar bear
publisher	American Society for Microbiology
publishDate	2018
url	https://doaj.org/article/4a29ec5b31974a29b9b04352edaa8b3b
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Novel Divergent Polar Bear-Associated Mastadenovirus Recovered from a Deceased Juvenile Polar Bear

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