Biology subjects

Boe, C. A.

Publications and source records attributed to Boe, C. A..

4 recordsLinked to original sources

bioRxiv2026

Highly Pathogenic Avian Influenza Viruses H5N1 and H5N5 in Red Foxes (Vulpes vulpes) in Norway during 2022-2024

Since 2020, highly pathogenic avian influenza (HPAI) A(H5Nx) clade 2.3.4.4b viruses have spread globally, causing extensive outbreaks in domestic and wild birds. Increased circulation has resulted in frequent spillover to mammals, and occasional mammal-to-mammal transmission. Although human infections remain rare, the zoonotic potential of these viruses continues to be a public health concern. We investigated six cases of HPAI in red foxes (Vulpes vulpes) in Norway during 2022-2024 and identified infections with H5N1 and H5N5 viruses. Pathological and virological investigations demonstrated systemic infection, with prominent lesions in the brain and/or lungs. Phylogenetic analyses showed high similarity between viruses detected in foxes and those concurrently circulating in wild birds. The mammalian adaptation marker PB2:E627K was identified in one H5N1 virus and as a minority variant in a second H5N1 virus.

microbiology↗

bioRxiv2026

Highly Pathogenic Avian Influenza H5N5 in a Polar Bear and Atlantic Walrus, Svalbard, 2026, with Widespread Seroconversion in Polar Bears

Highly pathogenic avian influenza virus (HPAIV) subtype H5N5 was detected in a one-year-old polar bear (Ursus maritimus) and an adjacent adult Atlantic walrus (Odobenus rosmarus rosmarus), both found deceased in Raudfjorden, Svalbard. This represents the first confirmed case of HPAI in a European polar bear and the second in an Atlantic walrus. Viral genomes were nearly identical and harbored PB2-E627V, a marker associated with mammalian adaptation. Several polar bears, including the deceased individual, had previously been observed feeding on the walrus carcass. Antibodies against H5 were detected in 75% of polar bears in 2023 (n=36) and 97% in 2024-2025 (n=65), suggesting extensive circulation of HPAIV in the population following the first detections in birds in Svalbard in 2022, whereas no antibodies were detected in samples from 2014-2022 (n=243).

molecular biology↗

bioRxiv2026

Multiple Introductions of Highly Pathogenic Avian Influenza Viruses into the High Arctic: Svalbard and Jan Mayen, 2022 - 2025

Between 2022 and 2025, highly pathogenic avian influenza viruses (HPAIVs) of clade 2.3.4.4b, including four distinct H5 Eurasian (EA) genotypes, were detected in wild birds and mammals in the Svalbard Archipelago and on the island of Jan Mayen. We describe their epidemiology and genomic characteristics to improve understanding of HPAIV occurrence and transmission in the High Arctic. The initial cases in 2022 occurred during summer and involved a glaucous gull (Larus hyperboreus) and great skuas (Stercorarius skua) on Svalbard and Jan Mayen, representing the first detections of HPAIVs in the High Arctic. Three HPAIV genotypes were identified: EA-2020-C (H5N1), EA-2021-AB (H5N1), and EA-2021-I (H5N5). In 2023, HPAIVs were detected in a broader range of bird species, and retrospectively in an Atlantic walrus reported by another research group (Odobenus rosmarus rosmarus). Genotypes identified in 2023 were EA-2020-C (H5N1), EA-2021-I (H5N5), and EA-2022-BB (H5N1). No cases were reported in 2024. In 2025, EA-2021-I (H5N5) was detected in Arctic foxes (Vulpes lagopus) on Svalbard, without preceding detections in wild birds. The foxes exhibited neurological symptoms, and necropsy of one individual revealed the presence of feathers in its stomach. All sequenced viruses from the Arctic foxes uniquely carried the combination of PB2-E627K and PB1-H115Q, which is associated with mammalian adaptation. The detection of multiple genotypes indicates repeated and independent introductions of HPAIVs into these regions. The co-circulation of genetically distinct virus strains in areas of high bird density further suggests that Arctic breeding grounds may facilitate local viral amplification, reassortment, and subsequent dissemination along migratory flyways, including transcontinental spread. Data summaryThe authors confirm all supporting data, code and protocols have been provided within the article or through supplementary data files. Influenza A whole genome sequences generated through this study are available under the GISAID accession numbers found in Table 1. All genome sequences and associated metadata supporting the findings of this study can be accessed through the persistent digital object identifier https://doi.org/10.55876/gis8.260211rq. O_TBL View this table: org.highwire.dtl.DTLVardef@15e1921org.highwire.dtl.DTLVardef@c3e91borg.highwire.dtl.DTLVardef@1fcfe78org.highwire.dtl.DTLVardef@a69606org.highwire.dtl.DTLVardef@c36c74_HPS_FORMAT_FIGEXP M_TBL O_FLOATNOTable 1.C_FLOATNO O_TABLECAPTIONDetections of highly pathogenic avian influenza virus (HPAIV) in wild birds and mammals sampled in the Svalbard Archipelago and on Jan Mayen from January 1st, 2022, to August 31st, 2025. C_TABLECAPTION C_TBL

microbiology↗

bioRxiv2025

Whole genome sequencing reveals a novel Renibacterium salmoninarum lineage and suggests geographic endemism combined with anthropogenic spread in the North-East Atlantic area

Renibacterium salmoninarum is the causative agent of bacterial kidney disease (BKD) and has been isolated from northern European salmonid farms since the 1960s. The bacterium has been detected only sporadically in Norway during the last decades, but the country experienced several geographically spread outbreaks since December 2022. The phylogenomic relationships of R. salmoninarum isolates associated with the epizootics ongoing on the West Coast and in Mid-Norway were explored using a whole genome sequencing approach. A broad overview of the phylogeography of this pathogen was gained through sequencing and analysis of a collection of isolates from Norway (n=67), Iceland (n=12), Denmark (n=12), and the Faroe Islands (n=1), along with a collection of 109 publicly available sequences. We identified two distinct contemporary clades of R. salmoninarum causing BKD in Norway in the period 2022-2024. Both clades belong to the expanding, aquaculture-associated Lineage 1. The epidemiological picture appears consistent with contemporary aquaculture operations, raising questions on the effectiveness or practice of current biosecurity practices towards R. salmoninarum. Our work also describes a hitherto undescribed lineage (Lineage 3), predominantly from Iceland, where BKD is considered endemic. The detection of endemic reservoirs of R. salmoninarum in European water systems underscores the potential for ongoing pathogen circulation independent of acute outbreaks. This finding emphasizes the importance of further investigation of the mechanisms of pathogen persistence, particularly within environments related to aquaculture, where chronic infection reservoirs could compromise disease management and biosecurity. IMPORTANCERenibacterium salmoninarum, the causative agent of bacterial kidney disease (BKD), is a chronic salmonid pathogen that often presents subclinically, complicating detection and control. Effective management of BKD is therefore crucial for sustainable aquaculture and wild fish conservation. Recognizing the need for comprehensive sampling, previous studies have underscored the importance of a global isolate collection to better understand the epidemiology of the pathogen. While the slow genetic evolution and highly conserved genome of the bacterium have reduced the resolution of conventional typing methods in the past, applying whole genome sequencing has enabled its molecular tracing at the outbreak level. Here, we present the largest phylogenomic analysis of R. salmoninarum to date, including sequences from Denmark, Iceland, and the Faroe Islands for the first time. This expanded dataset elucidates past and present movements of the pathogen in European waters, providing actionable insights to support development of targeted BKD management and biosecurity strategies.

genomics↗