Phylogenetic and Molecular Characterization of a Novel #Reassortant High-Pathogenicity Avian #Influenza #H7N6 Virus Detected in #NZ #Poultry

 

Abstract

H7 high-pathogenicity avian influenza (HPAI) virus outbreaks can cause high rates of morbidity and mortality in poultry flocks, leading to devastating impacts on poultry industries. In December 2024, an HPAI virus was detected on a poultry farm in New Zealand, being the first time a case of HPAI was reported in the country. Whole-genome sequencing, subtyping, phylogenetic, and mutation analyses were performed to characterize the virus. Results indicated a novel high-pathogenicity H7N6 avian influenza virus arose through a reassortment event between endemic low-pathogenicity H4N6 and H7 viruses, followed by two mutations at the H7 gene cleavage site. Mutation analysis suggests the novel H7N6 virus exhibits increased risk of host specificity shift, but further work is required to fully understand the functional impacts of the detected mutational events. In this instance, a timely biosecurity response was effective in eliminating the virus and preventing its transmission to secondary poultry flocks in New Zealand. However, the event underscores the critical importance of continued surveillance of commercial poultry and other potential avian carriers to facilitate early detection of low-pathogenicity avian influenza viruses, which may undergo reassortment or de novo mutation into high-pathogenicity variants.

Source: International Journal of Infectious Diseases, https://www.mdpi.com/1422-0067/26/21/10623

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Active #Surveillance for Emerging #Influenza A Viruses – Findings from a #OneHealth Study in #Vietnam’s Live Bird #Markets

 

Highlights

-- We conducted surveillance for influenza A viruses at live bird markets in northern Vietnam.

-- Six different subtypes of influenza A virus were found co-circulating in the markets.

-- Notable genetic mutations were found across many genes.

-- These markets have great potential to generate new pandemic influenza A virus strains.

Abstract

Objectives

Live bird markets (LBMs) in Asia have often been the source of human infections with avian influenza virus (AIV).

Methods

From July 2021 to August 2023, we employed a One Health approach in conducting periodic surveillance for novel influenza A viruses in five LBMs in northern Vietnam. Specimens were studied with egg culture, molecular assays, Sanger sequencing, and next-generation sequencing.

Results

We studied a total of 688 human, avian, and bioaerosol specimens. Among these, 118 (17.2%) were found to have molecular evidence of AIVs. Next-generation sequencing of 92 isolates revealed multiple AIV subtypes, including H4N6 (n=1), H5N1 (n=3), H5N8 (n=6), H6N2 (n=3), H6N6 (n=18), and H9N2 (n=61) and mix infections (n=7). Our H5Nx sequences belonged to the Eurasian lineage clade 2.3.4.4b, while our H6N2 sequences were of group III, H6N6 of group II, and H9N2 of the BJ94-lineage clade 4.6.14.

Conclusions

The relatively high prevalence of AIV, particularly highly pathogenic H5N1 and H5N8 viruses, along with the subtype diversity, frequent co-infections and notable mutations, highlights the urgent need for continued monitoring and control of AIV in Vietnam’s poultry farms and LBMs.

Source: International Journal of Infectious Diseases, https://www.ijidonline.com/article/S1201-9712(25)00354-6/fulltext

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Exploring Avian #Influenza Viruses in #Yakutia—The Largest #Breeding #Habitat of Wild Migratory #Birds in Northeastern #Siberia

Abstract

Yakutia, the largest breeding ground for wild migratory birds in Northeastern Siberia, plays a big role in the global ecology of avian influenza viruses (AIVs). In this study, we present the results of virological surveillance conducted between 2018 and 2023, analyzing 1970 cloacal swab samples collected from 56 bird species. We identified 74 AIVs of H3N6, H3N8, H4N6, H5N3, H7N7, H10N3, and H11N9 subtypes in Anseriformes order. Phylogenetic analysis showed that the isolates belong to the Eurasian lineage and have genetic similarities with strains from East Asia, Europe, and North America. Cluster analysis has demonstrated the circulation of stable AIV genotypes for several years. We assume that Yakutia is an important territory for viral exchange on the migratory routes of migrating birds. In addition, several amino acid substitutions have been found to be associated with increased virulence and adaptation to mammalian hosts, highlighting the potential risk of interspecific transmission. These results provide a critical insight into the ecology of the AIV and highlight the importance of continued monitoring in this geographically significant region.

Source: Viruses, https://www.mdpi.com/1999-4915/17/5/632

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Emerging #zoonotic potential of #H4N1 avian #influenza virus: enhanced #human #receptor binding and #replication via novel mutations

Abstract

Background

Avian influenza virus (AIV), a zoonotic pathogen found worldwide, includes multiple subtypes, one of which is the H4 subtype frequently detected in wild birds and poultry. Despite its prevalence, research on H4 subtype AIV has been scarce, with a focus predominantly on the H4N2 and H4N6 subtypes. The zoonotic potential of H4N1 has not been investigated to date.

Methods

In this study, we used gene sequencing in conjunction with bioinformatics methodologies to analyze wild-type H4N1 AIV strain and mutant strains emerging from serial passaging in cell culture. Furthermore, we assessed the zoonotic potential of H4N1 and the alterations caused by mutations via a series of phenotype assays, including evaluation of receptor binding affinity, immunofluorescence assays, analyses of growth kinetics across different animal cell cultures, and in vivo pathogenicity studies.

Results

Our research reveals that H4N1 AIV can bind to human receptors and exhibits an affinity for human lung and tracheal tissues. In vitro experiments demonstrate that H4N1 replicates efficiently in human cell lines. Furthermore, animal studies demonstrate that H4N1 can induce pneumonia in mice without the need for prior adaptation to the host. Notably, during passage in cell culture, H4N1 rapidly acquired two previously unreported mutations. These mutations significantly enhanced the virus’s ability to attach to human receptors and its capacity for replication.

Conclusions

In summary, our study provides preliminary experimental evidence for the emerging zoonotic potential of H4N1 AIV. These findings expand our knowledge of the H4 subtype AIV and reinforce the critical need for continued surveillance of AIV to prevent and prepare for potential outbreaks affecting human health.

Source: Virology Journal, https://virologyj.biomedcentral.com/articles/10.1186/s12985-025-02736-4

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