ETIDIOH - NEW

  Abstract We investigated the evolutionary history of the newly emergent neuraminidase (am4N1) associated with the D1.1 and D1.2 genotypes of highly pathogenic avian influenza A(H5N1) viruses in North America . Phylogenetic inference places am4N1 in a sister clade to Eurasian avian, swine, and human A(H1N1)pdm09 viruses and distinct from 1918, pre-2009 human seasonal, and classical swine A(H1N1) lineages . Am4N1 descends from diverse avian N1 genes endemic to the Americas. Phylodynamic analysis indicates a monophyletic am4N1 lineage with numerous introductions of viruses carrying the am4N1 gene likely originating from western Canada into the United States during emergence of the D1.1 and D1.2 genotypes. The lineage has diversified and accumulated deletions in the stalk domain . Despite amino acid divergence, structural modeling shows conserved neuraminidase architecture in the globular head . Given its distinct ancestry and amino acid sequence, further studies are needed to assess...

{Valparaíso} The birds shared a pond with wild birds. All birds were culled and buried on the property under strict biosecurity protocols. Cleaning and disinfection measures are being carried out. Source:  Link:  https://wahis.woah.org/#/in-review/7357 ____

  Abstract Highly pathogenic influenza A viruses of the H5 subtype continue to diversify worldwide through mutation and genetic reassortment , generating novel variants with unpredictable consequences under the One Health approach . Between 2024 and 2025 , five outbreaks of avian influenza A viruses were detected in backyard poultry across Michoacán, Estado de México , and Ciudad de México . We conducted molecular and genetic characterization of five highly pathogenic H5N2 viruses isolated from these events. All cases tested positive for influenza A virus and the H5 hemagglutinin , exhibiting high pathogenicity with intravenous pathogenicity index values ranging from 2.88 to 3.0. Whole-genome sequencing revealed novel reassortants containing hemagglutinin from Eurasian H5N1 clade 2.3.4.4b and neuraminidase from the endemic Mexican H5N2 lineage . The viral genome of the isolate from Michoacán contained six segments derived from Eurasian H5N1 viruses introduced into North America in ...

  Within the epidemiological surveillance carried out by the Colombian Agricultural Institute aimed at the early detection of clinical signs consistent with avian influenza, an outbreak of high pathogenicity avian influenza (HPAI) was confirmed in the village of Porvenir, in the municipality of Puerto Concordia in the department of Meta . The event concerns non-poultry in a backyard , for which respiratory and neurological signs were observed. The National Veterinary Authority activated epidemiological tracing and epidemiological monitoring actions in the area of origin of the affected birds. As a control measure, the stamping out of the birds in the epidemiological unit was carried out, and, as a complementary measure, epidemiological surveillance was strengthened in the surrounding area to identify other possible cases and prevent the spread of the disease. Source:  Link:  https://wahis.woah.org/#/in-review/7345 ____

  Abstract Background :  The emergence of the highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b in North America , beginning in February 2022, has highlighted the dynamic, unpredictable, and regionally variable risk of infections . Studies are needed to assess the spatiotemporal clustering of HPAI H5 at the interface between wild waterfowl and commercial poultry to understand and mitigate this risk .  Methods :  Publicly available data on HPAI H5 detections in wild birds and commercial poultry from January 2022 to January 2026 were analyzed at the county level. Retrospective space-time permutation models were used to identify and scan for clusters with higher than expected detection rates.  Results :  A total of 17,091 HPAI H5 detections were reported in wild birds across 1,467 county-level locations. Four species , Mallard ( Anas platyrhynchos ) (2,848 detections, 16.66%), Canada goose ( Branta canadensis ) (1,496, 8.75%), Green-winged teal ( An...

  Abstract A human infection with clade 2.3.4.4b H5N1 influenza A virus in Canada revealed minority variants E190D and Q226H in the hemagglutinin (HA) receptor-binding site (RBS). Because mutations at positions 190 and 226 have been associated with altered receptor specificity in other influenza subtypes, we investigated their impact on receptor binding in H5 HA . Using a recombinant protein approach and an ELISA-based glycan-binding assay , we assessed binding to representative avian- and human-type sialylated glycans . Both single mutations and their combination resulted in a complete loss of detectable binding to the tested glycans . To evaluate whether this phenotype was background-dependent, Q226H was additionally introduced into two other H5 HA proteins , each representing a distinct clade . In both cases, the mutation similarly abolished receptor binding . These findings independently validate recent glycan microarray observations and demonstrate that the patient-derived E19...

  Abstract Highly pathogenic avian influenza (HPAI) viruses of H5N1 clade 2.3.4.4b, are spreading worldwide , posing a threat to wildlife, domestic animals, and humans . In 2025, a multidisciplinary collaboration for HPAI H5N1 surveillance among birds within Galveston County, Texas , was initiated. Between November and December 2025, oropharyngeal and cloacal swabs were collected from wild and domestic birds reported as dead or dying by Galveston County residents . Specimens were studied with molecular assays, Sanger sequencing, virus isolation, and next-generation sequencing. Molecular evidence of HPAI H5N1 was detected in 7 of 10 (70%) birds, and the virus was successfully cultured in MDCK cells . Next-generation sequencing analysis of eight influenza A genome segments demonstrated a 4:4 gene segment reassortant constellation within clade 2.3.4.4b, consistent with genotype D1.1. Community members exposed to HPAI were offered antiviral prophylaxis . No human infections were identi...

  Abstract Since 2020, H5Nx high pathogenicity avian influenza viruses (HPAIVs) have caused widespread disruptions not only to global agriculture and trade but also to the health of free-ranging wildlife . Pinnipeds have experienced greater mortality from H5Nx HPAIV than any other mammalian taxa . Emergent virus strains, persisting over long time periods and vast geographic distances , have repeatedly triggered large-scale mortality events in pinniped populations. Of particular concern is the spread of H5Nx HPAIV to the Southern Hemisphere —including the emergence of a marine mammal-adapted clade in South America and detections in the sub-Antarctic and Antarctic —and to other remote locations such as the Hawaiian Islands . These developments elevate concern for the world’s endangered, isolated and endemic pinnipeds . While managing HPAIV in any animal population is a formidable task, working with free-ranging marine mammals poses unique challenges. In this review and perspective pi...

  Abstract Highly pathogenic avian influenza A H5N1 has recently expanded its mammalian host range ; in 2024, genotype B3.13 emerged in U.S. dairy cattle with pronounced mammary tropism . In the past, Influenza A virus immunology has been characterized primarily in respiratory infection models , whereas this study delineates immune responses after intramammary infection . An intramammary H5N1 challenge in Jersey cows in the early dry-off period enabled integration of dose- and compartment-resolved (alveoli versus teat cistern) cytokine and chemokine profiles with peripheral leukocyte dynamics and H5/N1-specific antibody responses. Infection-induced quarter-restricted, monophasic inflammatory networks peaking at 3 to 7 days post-infection , coordinated peripheral myeloid expansion and IFN gamma competent lymphocyte activation, and rising antibody titers across quarters. Competing Interest Statement The J.A.R. laboratory received support from Tonix Pharmaceuticals, Xing Technologies,...

  Abstract Wastewater monitoring enables non-invasive, population-scale tracking of community infections independent of healthcare-seeking behavior and clinical diagnosis. Metagenomic sequencing extends this capability by enabling broad, pathogen-agnostic detection, genomic characterization , and identification of novel or unexpected threats . Here, we present data from CASPER (the Coalition for Agnostic Sequencing of Pathogens from Environmental Reservoirs), a U.S.-based wastewater metagenomic sequencing network designed for deep, untargeted pathogen monitoring at national scale. This release includes 1,206 samples collected between December 2023 and December 2025 from 27 sites across nine states , covering 13 million people . Deep sequencing (~1 billion read pairs per sample) generated 1.2 trillion read pairs ( 347 terabases ), enabling detection of even rare taxa , with CASPER representing 66% of all untargeted wastewater sequencing data currently available on the NCBI Sequence ...

  Backyard poultry in the Bijelo Polje Region. Source:  Link:  https://wahis.woah.org/#/in-review/7334 ____

  Abstract The development of broadly protective and dose-sparing influenza vaccines remains a critical challenge , particularly for zoonotic H5N1 strains with pandemic potential . This study evaluates BECC470s, a synthetic TLR4 adjuvant , for its ability to enhance the immunogenicity and protective efficacy of recombinant H5 hemagglutinin (rHA) vaccination in murine models . BECC470s-adjuvanted rHA elicited robust IgG1/IgG2a antibody responses and complete survival following homologous 2004 H5N1 challenge in a prime–boost model . Although BECC470s broadened antibody binding to both variable HA head and conserved stalk domains by ELISA, functional neutralizing antibody responses were restricted to the matched 2004 H5N1 isolate, with no detectable neutralization of H5N1 viruses isolated in 2022 or 2024. These data indicate that BECC470s enhances the magnitude and apparent breadth of binding antibody responses while maintaining strain-specific neutralizing activity, supporting its po...

{England, North Yorkshire} 22.7k commercial pheasant rearing premises. Samples taken were positive for HPAI H5N1. Birds presented clinical signs prior to testing. Source:  Link:  https://wahis.woah.org/#/in-review/7337 ____

  Fourteen Coscoroba Swans in the Región de Valparaíso, Comuna Santo Domingo. Source:  Link:  https://wahis.woah.org/#/in-review/7336 ____

  Abstract Transmission of highly pathogenic avian influenza from H5 clade 2.3.4.4b has expanded in recent years to infect large populations of birds and mammals , heightening the risk of a human pandemic . Influenza viruses that are adapted to transmission in birds and a variety of mammals tend to have a less stable hemagglutinin (HA) than seasonal influenza viruses, enabling membrane fusion at comparatively higher pH levels . Here, we combined five mutations in the H5 HA that increased its melting temperature and promoted stable closure of the HA trimer . Structural analysis by cryo–electron microscopy revealed that the stabilizing mutations create several new hydrophobic interactions while maintaining the local HA structure . We found that vaccinating mice with stabilized H5 HA immunogens resulted in higher hemagglutination inhibition and neutralization titers than nonstabilized comparators. Epitope mapping of vaccine-elicited polyclonal antibody responses using negative-stain e...

  Abstract Highly pathogenic avian influenza virus of the H5N1 subtype has been infecting U.S. dairy cattle and spreading among dairy operations since March 2024. H5N1 surveillance systems for dairies are needed, but information on whether environmental sampling can inform these systems is lacking. To guide a surveillance framework , we determined the environmental sites with Influenza A virus (IAV) detection on H5N1-affected dairies (n = 25) in four states (California, Colorado, Michigan, and Ohio) and explored sample characteristics that may have influenced detection. A total of 581 samples from dairy environmental sites were characterized for IAV RNA via rRT-PCR, and classified into six categories . A total of 94 samples (16.2%) had IAV detected, and the Ct values measured from these samples were typically higher than those measured in bulk tank milk from a subset of sampled herds. A majority of IAV detections were made from the following site categories: milking equipment/perso...

  Abstract Highly pathogenic avian influenza (HPAI) clade 2.3.4.4b H5N1 virus has recently emerged in dairy cattle in the United States . The virus replicates primarily in the mammary gland of infected cattle, leading to dramatic reductions in milk production . It is thought that the virus transmits from animal to animal through viral shedding in milk , and therefore, vaccines that decrease the amount of virus in milk can potentially limit the current outbreak and reduce the risk of H5N1 spillover into humans . Here, we assess the immunogenicity and efficacy of a clade 2.3.4.4b H5 mRNA-LNP vaccine in lactating dairy cows . We found that the H5 mRNA-LNP vaccine elicited robust antibody responses in sera and milk and significantly reduced viral replication and disease caused by clade 2.3.4.4b H5N1 intramammary infection. Competing Interest Statement S.E.H. and D.W. are co-inventors on patents that describe the use of nucleoside-modified mRNA as a platform to deliver therapeutic prote...

  Abstract Dairy cattle have emerged as a prolific amplifying host for highly pathogenic avian influenza virus (HPAIV) H5N1 clade 2.3.4.4b and a new source for cross-species and zoonotic transmission . Independent introductions of H5N1 with unclear exposure routes have been reported in several dairy herds across the U.S. These events escalate the pandemic potential of HPAIV H5N1 as transmission within and between mammalian species present opportunities for mammalian adapted H5N1 viruses to emerge . Although more than 1000 herds have been infected, bovine H5N1 influenza virus pathogenesis, transmission, and evolution in dairy cattle remains not well characterized. Working with H5N1-infected lactating cattle in high containment has been a major challenge due to the required infrastructure and logistics associated with housing, husbandry, and waste management for this model. Thus, developing alternative bovine models that maintain biological relevance while reducing operational comple...

  Abstract Antibodies to the influenza hemagglutinin protein (HA) confer the strongest protection against infection . Immunity elicited by endemic, seasonal, human viruses is correlated with diminished disease severity and death caused by antigenically novel viruses. Antibodies to the HA head interface are broadly protective and abundant in human serologic and memory repertoires . Notably, few head interface antibodies from H5 naive donors are reported to bind H5 HAs . We find head interface antibodies engage a wide range of H5 isolates but fail to engage most isolates from the goose Guangdong (GsGd) lineage . We identify a single substitution, P221S, largely dictates antibody binding. Phylogenetic analysis indicates that P221S arose in a Chinese avian reservoir by the year 2000 . Descendants of these viruses have caused the current global panzootic and have achieved sustained mammal-mammal transmission in farmed and wild mammals. Our findings demonstrate that viral evolution in no...

  A poultry farm in Bihar State. Source:  Link:  https://wahis.woah.org/#/in-review/7319 ____