15th October 2021 Product update: rapidvirology staff writer
Single AA Change in H5N8 Shown in Adaptation From Avian to Mammalian Species at UK Wildlife Centre
The US CDC has published the UK's Animal and Plant Health Agency (APHA) report on last winter's avian flu outbreak at a wildlife rehab center where the Highly-Pathogenic H5N8 subtype of Influenza A spread between 5 swans, 5 seals, and one fox that resulted in their death.
Swabs taken from the swans and seals, and tissue samples taken from the seals and fox were analyzed for influenza A nucleic acid using a screening real-time reverse transcription PCR (rRT-PCR) assay, followed by an H5 subtype-specific rRT-PCR assay which confirmed the presence of H5N8 subtype.
Where the subtype-specific rRT-PCR assay detected positive samples, these positives were then isolated using specified pathogen-free embryonated fowl eggs, and whole-genome sequencing was performed on them using the MiSeq platform (Illumina).
The genomes of the fox, seal, and swan-derived viruses were homologous at the amino-acid level, except a single amino-acid substitution at position 701 in the polymerase basic protein 2 gene (D701N) that was only present in the fox and seal sequences.
For histologic examination, samples of heart, lung, liver, spleen, and brain tissues were collected from the swans, fox, and seals, as well as lymph nodes of the mammalian species, and these were fixed in 10% neutral buffered formalin before processing for hematoxylin and eosin staining and immunohistochemical (IHC) examination.
An IHC examination was performed by using anti-influenza A nucleoprotein primary antibody (Statens Serum Institute), and anti–canine distemper virus nucleoprotein mouse monoclonal primary antibody (Bio-Rad) in selected fox tissues.
Although genetic analyses indicated no increased risk for human infection with the H5N8 viruses in this outbreak and no human influenza-like illness was reported in the weeks after the event, this episode demonstrates how these viruses can have unexpected and severe health risks for mammals.
Date Published: 15th October 2021
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Note: This content has been edited by a rapidvirology.com staff writer for style and content.
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