ETIDIOH - NEW

  Abstract Avian influenza A(H9N2) has been circulating in poultry across Asia, the Middle East, and Africa, posing human health risks . In Ghana , it has co-circulated among poultry with influenza A ( H5N1 ). This report describes Ghana’s first confirmed human case of avian influenza A(H9N2) virus infection in a two-year-old boy from Upper East Region , identified through active respiratory surveillance . Molecular and genomic analyses confirmed the virus was of the G1 lineage , closely related to other West African strains , with mammalian adaptive mutations known to increase human infection potential. The child experienced mild symptoms , received outpatient care, and recovered. Health authorities conducted epidemiological investigations . No source was identified for the child’s infection; no additional human infections were detected. This case highlights the importance of robust avian influenza surveillance in animals and humans, particularly in regions with human-animal inter...

  Abstract Stabilizing the pre-fusion structures of antigenic proteins can enhance the effectiveness of antiviral vaccines . The pre-fusion form of hemagglutinin (HA) from the influenza virus typically adopts a stable trimeric structure . However, the recombinant ectodomain of HA from the A/California/04/2009 (H1N1) influenza virus formed a monomer in solution rather than the expected trimer. To promote trimer formation in the pre-fusion conformation, we redesigned five amino acid residues in the stem region of HA that are involved in trimerization. The engineered HA protein formed a stable trimer at both pH 8.0 and pH 5.5. Additionally, the thermal stability of the modified protein improved, as indicated by an approximately ten-degree increase in its denaturation temperature. Cryo-EM analysis at 2.2 angstrom resolution confirmed that the mutant HA protein adopted the pre-fusion structure. Furthermore, the stabilized mutant exhibited enhanced immunogenicity in mice . We applied the...

  ABSTRACT Alterations in the PB2-627 domain of avian influenza virus (AIV) can potentially increase the risk of cross-host species infections in humans and mammals . Recently, there has been a rise in human cases of AIV infections without the presence of the known mammalian determinant PB2-E627K . Here, we identified a variant, PB2-627V , which has evolved in poultry and has contributed to the increase in human AIV infections . By screening global PB2 sequences , we discovered a new independent cluster of PB2-627V that emerged in the 2010s , prevalent in avian, mammalian, and human AIV isolates , including those of H9N2, H7N9, H3N8, 2.3.4.4b H5N1 , and other subtypes. We functionally assessed its host adaptation , fitness , and transmissibility across three subtypes of AIVs (H9N2, H7N9, and H3N8) in different host models . PB2-627V combines the viral properties of avian-like PB2-627E and human-like PB2-627K , facilitating AIVs to efficiently infect and replicate in chickens and mi...

Abstract Avian influenza A viruses (AIVs) pose a significant pandemic threat due to their cross-species transmission potential . However, AIV surveillance at the critical “ migratory birds–poultry-exposed population ” interface remains limited. Between 2021 and 2024, we implemented a prospective One Health surveillance program around Nansi Lake , monitoring AIVs in migratory birds, poultry, and environmental samples, as well as serological investigations against representative AIVs among migratory birds or poultry-exposed subjects. AIVs were detected in 2.1% (30/1417) of migratory bird samples and 10.2% (100/978) of poultry samples . Among these, we identified ten highly pathogenic avian influenza (HPAI) H5 subtype viruses, one HPAI H7N9 virus, and five low pathogenic avian influenza (LPAI) H9N2 viruses. Phylogenetic analysis revealed evidence of frequent genomic reassortment events involving H5 subtype viruses among migratory birds, poultry, and humans . Serological investigation also...

  {Excerpt} Avian influenza A(H9N2) :  -- Guangdong Province : - 1) An individual with onset on May 28, 2025.  -- Hubei Province :  - 2) An individual with onset on June 21, 2025.  (...) Source: Centre for Health Protection, Hong Kong PRC SAR,  https://www.chp.gov.hk/en/resources/29/332.html ____

  New human cases {2}:  -- From 28 May to 1 July 2025 , based on reporting date, the detection of influenza A( H5N1 ) in nine humans , influenza A( H9N2 ) in three humans and influenza A( H10N3 ) in one human were reported officially. Additionally, one human case of infection with an influenza A(H5N1) virus was detected.  Circulation of influenza viruses with zoonotic potential in animals :  -- High pathogenicity avian influenza (HPAI) events in poultry and non-poultry continue to be reported to the World Organisation for Animal Health (WOAH).{3} The Food and Agriculture Organization of the United Nations (FAO) also provides a global update on avian influenza viruses with pandemic potential.{4}  Risk assessment {5}:  -- Sustained human to human transmission has not been reported from these events.  -- Based on information available at the time of the risk assessment, the overall public health risk from currently known influenza viruses circulating at t...

Abstract The current study aimed to investigate the genetic characterization and evolution of low pathogenic avian influenza virus H9N2 in Egypt . Ten H9N2 viruses were recently isolated from samples collected between 2019 and 2023. Phylogenetic analysis of the haemagglutinin (HA) gene segment of the H9N2 isolates showed a relatedness with G1 H9 4.2 lineage and clustered within genotype III of the Egyptian strains identified earlier in 2018. The majority of H9N2 strains had seven and eight glycosylation sites in HA and neuraminidase (NA) respectively . All strains carried H191 and L234 residues in their hemagglutinin which are markers facilitating avian-to-human cross species barrier transmission . No stalk deletions were detected in NA gene. In addition, genetic analysis of the NA and M encoding proteins revealed the absence of substitutions associated with resistance to oseltamivir and amantadine . The NA showed S372A and R403W substitutions which were previously detected in H3N2 and...

Abstract Highly pathogenic avian influenza of the H5N1 subtype has shown recent unprecedented expansion in its geographic and host range , increasing the pandemic threat . The younger age of H5N1 versus H7N9 avian influenza in humans has previously been attributed to imprinted pre-immunity to hemagglutinin stalk (HA2) epitopes shared with group 1 ( H1N1, H2N2 ) versus group 2 ( H3N2 ) influenza A subtypes predominating in the human population before versus after 1968, respectively. Here we review the complex immuno-epidemiological interactions underpinning influenza risk assessment and extend the imprinting hypothesis to include a potential role for cross-protective neuraminidase (NA) imprinting . We compare H5N1 distributions and case fatality ratios by age and birth cohort (as proxy for HA2 and/or NA imprinting epoch) not only to H7N9 but also H5N6 and H9N2 avian influenza, representing more varied conditions of zoonotic influenza relatedness to human subtypes of the past century. We...

Abstract Background Avian influenza is an infectious disease of birds caused by the influenza A virus, which can infect a variety of domestic,wild birds and even cross the species barrier and infect humans.To understand the contamination of avian influenza virus in the external environment of poultry in Huzhou City from 2017 to 2023 and to assess the risk of human infection with avian influenza. Methods A total of 3,400 environmental specimens from five types of venues in Huzhou City were collected and tested for influenza A virus nucleic acid using fluorescent reverse transcription polymerase chain reaction (RT-PCR). Results From 2017 to 2023, with 15.44% overall positive rate of influenza A virus . The predominant subtype of avian influenza virus was H9 (accounting for 54.67%). The peak of positive influenza virus detection rates occurred in winter and spring seasons every year. The venue with highest positive rate was poultry slaughtering and processing plants (41.83%), followed by ...

Abstract H9N2 avian influenza virus (AIV) is a globally prevalent pathogen that causes economic losses in poultry and poses zoonotic threats . Due to antigenic drift and shift, traditional inactivated vaccines often show reduced efficacy . This study presents a novel subunit vaccine based on a conserved HA6 scaffold derived from the hemagglutinin stem domain and coupled with a fusion peptide epitope (fPE) via Snoopligase-mediated ligation. The HA6 protein was validated by its binding to the broad-spectrum antibody CR6261, and the fPE-HA6 fusion construct incorporated T- and B-cell epitopes. Immunization trials in a chicken demonstrated that fPE-HA6 induced stronger humoral and cellular immune responses than individual immunogens. Upon challenge with H9N2 strains YZ4 and SN, the fusion vaccine significantly reduced viral shedding, demonstrating broad-spectrum protection. These findings highlight the potential of HA6 as a modular scaffold for influenza vaccines and the utility of Snoopli...

{Excerpt} Epi-Week 25 2025 Avian influenza A(H9N2) :  - Henan Province :  -- 1) A 52-year-old woman with onset on May 10, 2025.  - Hunan Province :  -- 2) A 72-year-old woman with onset on May 14, 2025.  - Sichuan Province :  --3) A six-year-old boy with onset on May 14, 2025. Avian influenza A(H10N3) :  - Shaanxi Province :  -- 1) A 70-year-old woman with onset on April 21, 2025.  (...) Source: Centre for Health Protection, Hong Kong PRC SAR,  https://www.chp.gov.hk/files/pdf/2025_avian_influenza_report_vol21_wk25.pdf ____

ABSTRACT Influenza A (H3N2) viruses are historically responsible for the 1968 Hong Kong flu pandemic. Since then, H3N2 has continued to circulate as a seasonal influenza virus in humans. Public health concerns were raised in 2022 when human infections with novel reassortant H3N8 influenza viruses originating from chickens were first reported in China . Here, we conducted a systematic surveillance of H3 avian influenza viruses (AIVs) circulating in poultry and assessed the public health risk of emergent H3 reassortants. We found that H3 AIVs were prevalent in both ducks and chickens . Notably, in December 2022, a novel chicken-derived H3N3 subtype virus was identified, which gradually replaced the previously predominant H3N8 virus and became prevalent in chickens. Genetic analysis demonstrated that the novel H3N3 virus is a triple-reassortment strain with the H3 gene segment from chicken H3N8 virus, the N3 gene segment from the H10N3 virus , and internal gene segments derived from H9N2 ...

ABSTRACT Several emerging influenza viruses, including H7N9 and H5N6 viruses, trace their origins to reassortment with H9N2 viruses that contributed internal gene segments. However, the evolutionary constraints governing the reassortment of H9N2 viruses remain unknown. In seasonal human influenza A viruses, gene segments coevolve at both the nucleotide and amino acid levels. Here, we demonstrate that evolutionary relationships between gene segments, including polymerase subunits in human H3N2 viruses, differ from avian H9 viruses . Avian H9 viruses were characterized by little coevolution between gene segments or between polymerase subunits. Strikingly, protein trees built from avian H9 polymerase subunits diverge despite known functional constraints on polymerase evolution. The evolutionary divergence observed between gene segments of avian H9 viruses was consistent across isolates from different continents, suggesting that coevolution between H9 gene segments is not dependent on regi...

Abstract Nationwide surveillance of avian influenza viruses (AIVs) in live poultry markets across China has occurred since 2014, providing a resource for AIV prevalence and genetic diversity studies . Here we report that 3,237 of 18,425 samples from poultry were AIV positive (17.57%) between 2019 and 2023, with H9N2 being the dominant subtype . We developed an automated phylogeny-based nomenclature system to classify genetic clades of the dominant H9N2 lineage, the BJ94 lineage. Using this model, we found that ten haemagglutinin (HA) sub-subclades cocirculated in poultry and showed antigenic variation. In addition, 99.46% and 96.17% of H9N2 AIVs in 2021–2023 possessed human-receptor binding-related HA-L226 and human MxA-resistance-related NP-N52 mutations , respectively. H9N2 strains with these two mutations preferred human-type receptors and increased replication in human cells in vitro, regardless of the presence of PB2-V/K/E627. Moreover, H9N2 AIVs containing HA-L226, PB2-V/K627 and...

  New human cases {2}:  -- From 23 April to 27 May 2025, based on reporting date, the detection of influenza A( H5N1 ) in three humans, the detection of influenza A( H9N2 ) virus in eight humans and the detection of influenza A( H10N3 ) in one human were reported officially.  -- Circulation of influenza viruses with zoonotic potential in animals:  - High pathogenicity avian influenza (HPAI) outbreaks in poultry and non-poultry animals continue to be reported to the World Organisation for Animal Health (WOAH).{3}  - The Food and Agriculture Organization of the United Nations (FAO) also provides a global update on avian influenza viruses with pandemic potential.{4}  -- Risk assessment {5}:  - Sustained human to human transmission has not been reported in these events. Based on information available at the time of the risk assessment , the overall public health risk from currently known influenza viruses circulating at the human-animal interface has not c...