The identification and genetic characteristics of the #Orf #virus strain (ORFV-CL24) isolated from #Jilin province, #China

 

Abstract

Orf virus (ORFV), the prototype species of the Parapoxvirus genus within the Poxviridae family (subfamily Chordopoxvirinae), is a global pathogen infecting sheep, goats, and other ruminants, with zoonotic potential for humans. In this study, an outbreak of ORFV infection occurred in a sheep flock in Changling County, Jilin province, China, causing papules, pustules, and crusting lesions on the lips and eyelids. Typical parapoxvirus particles were observed using electron microscopy, and a wild ORFV strain was isolated, characterized, and designated as ORFV-CL24. To clarify the epidemiological and genomic characteristics of ORFV in the region, we completed its whole-genome sequencing (GenBank accession number: PV126639). Genome analysis revealed that ORFV-CL24 shares a conserved structure with other isolates available in GenBank, which possess a complete genomic sequence of 138,500 bp of dsDNA harboring 131 putative open reading frames (ORFs) flanked by inverted terminal repeat (ITR) regions of 3,264 bp at both termini. Additionally, the genome exhibited high GC-content (63.3%), indicating its key role in DNA stability. Phylogenetic analysis placed the wild strain within a subclade with the attenuated ORFV strain D1701, implying a putative common ancestor or epidemiological linkages. Further analysis of B2L (ORFV 011) and E3L (ORFV 020) genes further revealed genetic diversity and evolutionary patterns. Notably, despite phylogenetic relatedness, specific mutations in ORF020 further distinguished ORFV-CL24 from D1701, reflecting stepwise mutation accumulation during host adaptation. In conclusion, our results provided valuable genetic insights into ORFV-CL24, which contributed to a better understanding of its evolution, biological properties, and endemic trends in China.

Source: Frontiers in Microbiology, https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2025.1658326/full

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Detection of #antibodies specific to #H5 avian #influenza virus in a #sheep in #Norway, June 2024 ...

 

Abstract

A 2023 outbreak of highly pathogenic avian influenza in seabirds in Norway caused substantial environmental contamination of grazing areas frequented by local sheep. Eleven months later, 220 sheep were tested for antibodies to type A influenza and H5 subtype using ELISA, haemagglutination inhibition, and microneutralisation assays. One ewe (0.5%) tested positive by all methods, consistent with prior spillover infection. This underscores the importance of restricting livestock access to outbreak areas to mitigate cross-species transmission and zoonotic risk.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.08.14.670265v1

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Detection of clade 2.3.4.4b #H5N1 high pathogenicity avian #influenza virus in a #sheep in #UK, 2025

Abstract

Clade 2.3.4.4b H5N1 high pathogenicity avian influenza virus (HPAIV) continues to pose a significant global threat, affecting wild and domestic avian populations, and mammalian species. In early 2024, H5N1 HPAIV was detected in dairy cattle in the United States of America, where it has continued to circulate, with sporadic detections also reported in other ruminant species. The detection of high viral loads in milk from infected cattle, has resulted in several human infections, underscoring the zoonotic potential of these viruses. In response, several countries have intensified surveillance in non-avian species to evaluate the potential for undetected viral circulation in captive mammals. In Great Britain, bulk milk tank testing of cattle and targeted surveillance of captive mammalian species on an infected premises is undertaken in accordance with the outcome of a rapid risk assessment undertaken to determine the epidemiological links between the poultry and captive mammals. A result of this testing was the first recorded detection of clade 2.3.4.4b H5N1 HPAIV in a sheep in March 2025, identified on an infected poultry premises in Great Britain. An initial seropositive result in a single ewe triggered further investigation, confirming serological positivity across repeated sampling and the presence of viral RNA in milk samples. This detection was confined to a single animal and was likely attributable to proximity to infected poultry and a presumed heavily contaminated environment. The implications of this ruminant detection are discussed in the context of interspecies transmission and surveillance strategies.

Source: BioRxIV, https://www.biorxiv.org/content/10.1101/2025.06.27.661969v1

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#UK, #England: Confirmed findings of #influenza of #avian origin in captive #mammals (as of March 25 '25)

Sheep, March 2025

One domestic sheep (Ovis aries) tested positive for influenza of avian origin (H5N1) in March 2025. The case was identified following routine surveillance of farmed livestock on a premises in Yorkshire where highly pathogenic avian influenza (H5N1) had been confirmed in other captive birds. The single animal was a ewe with signs of mastitis but no other clinical signs. The milk was positive by polymerase chain reaction (PCR) and the blood tested positive for H5 antibodies.  

All affected birds and the infected ewe were humanely culled to mitigate the risk of further disease spread. Further official testing of the remaining flock of sheep were all negative for the presence of avian influenza virus.

Source: DEFRA, https://www.gov.uk/government/publications/bird-flu-avian-influenza-findings-in-captive-mammals/confirmed-findings-of-influenza-of-avian-origin-in-captive-mammals

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