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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#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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The novel #H10N3 avian #influenza virus acquired #airborne #transmission among #chickens: an increasing threat to public health

ABSTRACT

Following two human infections with the H10N3 avian influenza virus (AIV) in 2021 and 2022, a third case was discovered in Yunnan, China, in 2024, raising concerns about the potential for future pandemics. Recent studies have indicated that novel H10N3 viruses are highly pathogenic in mice and can be transmitted between guinea pigs via respiratory droplets without prior adaptation. However, the biological characteristics of novel H10N3 in poultry have not been fully elucidated. Our findings revealed that H10 subtype AIVs are predominantly prevalent in waterfowl. Notably, H10N8 and H10N3 viruses that have infected humans were primarily isolated from chickens. For the first time, double basic hemagglutinin cleavage sites (motif PEIKQGR↓GL) were identified in novel H10N3 AIVs, which exhibit enhanced replication in chickens, and can be transmitted between chickens through direct contact and respiratory droplets. Animal experimental studies demonstrated that ducks are also susceptible to H10N3 viruses and that the virus is transmissible through direct contact, suggesting a greater risk of transmission and recombination. Serological studies conducted among poultry workers suggest that while the human population was largely naïve to H10N3 infection, sporadic and undetected human infections did occur, indicating a potential increasing trend. These data further emphasize the growing threat to public health posed by zoonotic H10N3 subtype AIVs.

Source: mBio, https://journals.asm.org/doi/10.1128/mbio.02363-24

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