Pathogenicity, #transmissibility, and #receptor #binding of a #human-isolated #influenza A #H10N5 virus

ABSTRACT

Recently, human infections with H10 influenza viruses, including H10N8 and H10N3, have been reported. In January 2024, a case of H10N5 and H3N2 co-infection was reported in Zhejiang Province, China, which is the first human infection with H10N5 avian influenza virus (AIV) globally. Almost simultaneously, we isolated a wild bird-derived H10N5 strain similar to the human H10N5 strain. To assess the public health risk, it is necessary to understand the zoonotic characteristics of these novel H10N5 viruses. Here, we evaluated the biological characteristics of human H10N5, wild bird H10N5, as well as poultry H10N8 in vitro and in vivo. We demonstrate that the novel H10N5 isolates infected and replicated effectively in human lung epithelial cells. They infected BALB/c mice without adaptation, which exhibited robust pathogenicity and caused mouse death. In guinea pig transmission experiments, the H10N5 strain spread through neither direct contact nor airborne exposure, whereas H10N8 transmitted effectively. Additionally, H10N5 exhibited dual receptor-binding characteristics with a stronger preference for avian receptors. The current public health risk of H10N5 is low. However, the occasional spillover infections of H10 AIV into humans and dual receptor-binding characteristics suggest a potential risk of cross-species transmission.

IMPORTANCE

In 2024, the H10N5 AIV was first reported to infect humans. Concurrently, we isolated a strain of H10N5 from wild birds that was highly similar to the human H10N5 strain. However, the zoonotic potential and the associated public health risks of the H10N5 virus remain unclear. In this study, we systematically evaluated the replication characteristics of human H10N5, wild bird H10N5, and poultry H10N8 in human lung epithelial cells, the virulence in mice, the transmission capabilities in guinea pigs, and the receptor-binding properties. Our results demonstrate that these novel H10N5 viruses have not yet acquired the ability to transmit in guinea pigs, but they possess the potential to infect mammals. These findings provide timely insights and warnings for the development of public health prevention strategies.

Source: mBio, https://journals.asm.org/doi/10.1128/mbio.00731-25

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A #human-infecting #H10N5 avian #influenza virus: #clinical features, virus #reassortment, #receptor-binding affinity, and possible #transmission routes

Abstract

Background

In late 2023, the first human case caused by an H10N5 avian influenza virus (AIV) was diagnosed in China. H10Ny AIVs have been identified in various poultry and wild birds in Eurasia, the Americas, and Oceania.

Methods

We analyzed the clinical data of the H10N5 AIV-infected patient, isolated the virus, and evaluated the virus receptor-binding properties together with the H10N8 and H10N3 AIVs identified in humans and poultry. The genomic data of the human-infecting H10N5 strain and avian H10Ny AIVs (n = 48, including 16 strains of H10N3 and 2 strains of H10N8) from live poultry markets in China, during 2019–2021, were sequenced. We inferred the genetic origin and spread pattern of the H10N5 AIV using the phylodynamic methods. In addition, given all available nucleotide sequences, the spatial-temporal dynamics, host distribution, and the maximum-likelihood phylogenies of global H10 AIVs were reconstructed.

Findings

The first H10N5 AIV-infected human case co-infected with seasonal influenza H3N2 virus was identified. Unfortunately, the patient died after systematic treatments. The H10N5 virus predominantly bound avian-type receptor, without any known mammalian-adapted mutations. Phylodynamic inference indicated that the H10N5 AIV was generated by multiple reassortments among viruses from Korea and Japan, central Asia, and China in late 2022, acquiring the seven gene segments from H10N7 or other low pathogenic AIVs in wild Anseriformes, except for the PA gene from H5N2 AIVs in Domestic Anseriformes. The HA gene of the H10N5 virus belongs to the North American lineage, which was probably introduced into Asia by migratory birds, subsequently forming local circulation.

Interpretation

Unlike the human-infecting H10N3 and H10N8 AIVs acquiring six internal protein-coding genes from H9N2 AIVs in domestic poultry, the human-infecting H10N5 AIV was generated through multiple reassortments among viruses mainly carried by wild Anseriformes. Furthermore, worldwide distribution, inter-continental transmission, and genetic exchanges between Eurasian and North American lineages call for more concerns about influenza surveillance on H10Ny AIVs, especially in the flyway overlapping areas.

Source: Journal of Infection, https://www.journalofinfection.com/article/S0163-4453(25)00050-7/fulltext

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North #American-Origin #Influenza A (#H10) viruses in Eurasian Wild #Birds (2022–2024): Implications for the Emergence of Human #H10N5 Virus

Abstract

During our surveillance of avian influenza viruses (AIVs) in wild birds across China, H10Nx viruses were isolated from diverse migratory flyways between 2022 and 2024. We identified one wild-bird H10N5 strain that shared a common ancestor with the human H10N5 virus in multiple gene segments. Phylogenetic and molecular dating revealed the origin and evolution of H10N5, highlighting the need for continued monitoring.

Source: Emerging Microbes and Infections, https://www.tandfonline.com/doi/full/10.1080/22221751.2025.2465308

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#Gene flow and its sporadic #spillover: #H10 and #N5 avian #influenza viruses from wild #birds and the #H10N5 #human cases in #China

Abstract

On 30 January 2024, China announced the first human case of H10N5 influenza infection. Prior to this, human cases of H10N7 and H10N8 had been reported. It is now appropriate to re-examine the evolution and future epidemiological trends of the H10 and N5 subtypes of avian influenza viruses (AIVs). In this study, we analyzed the reassortment characteristics of the first human-derived H10N5 AIV (A/Zhejiang/ZJU01/2023), as well as the evolutionary dynamics of the wild bird-derived H10 and N5 subtypes of AIVs over the past decade. Our findings indicate that the human-derived H10N5 AIV exhibited low pathogenicity. A/bean_goose/Korea/KNU-10/2022(H10N7) and A/mallard/Novosibirsk_region/962k/2018(H12N5) were identified as the potential reassortment parents. The virus has existed since 2022 and several isolations have been reported in Bangladesh. Phylogenetic analysis showed that H10Ny and HxN5 AIVs in China are clustered differently based on the East Asian-Australian (eastern) and Central Asian-Indian (western) migratory flyways. The H10Ny and HxN5 AIV reassortant strains may cause human infections through accidental spillover. It is possible that another center of AIV evolution, mutation, and reassortment may be developing along the migratory flyways in northeastern Asia, distinct from Europe, the Americas, and China's Yangtze River Delta and Pearl River Delta, which should be closely monitored to ensure the safety of the public.

Source: Virologica Sinica, https://www.sciencedirect.com/science/article/pii/S1995820X24001986?via%3Dihub

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