ETIDIOH - NEW

Abstract Prior to the discovery of bat influenza A virus (IAV) subtypes H17N10 and H18N11 , all IAVs were thought to bind sialic acid residues via hemagglutinin (HA) to mediate attachment and subsequent viral entry. However, H17 and H18 engage a proteinaceous receptor : the major histocompatibility complex class II (MHCII). The mechanistic details of this hitherto unknown protein-mediated entry are not understood. Given that conventional IAVs rely on multivalent binding to sialylated glycans , we hypothesized that bat HA similarly interacts with multiple MHCII molecules. Using photoactivated localization microscopy (PALM) on fixed and live cells, we demonstrate that bat IAV particles attach to pre-existing MHCII clusters and induce a further increase in cluster size upon binding. To measure the impact of viral attachment on the dynamics of MHCII, we employ an “inverse attachment” approach, immobilizing viral particles on coverslips before seeding live MHCII-expressing cells on top. Sin...

Abstract During infection, individual virions trigger specific cellular signaling at the virus-cell interface , a nanoscale region of the plasma membrane in direct contact with the virus. However, virus-induced receptor recruitment and cellular activation are transient processes that occur within minutes at the nanoscale. Hence, the temporal and spatial kinetics of such early events often remain poorly understood due to technical limitations. To address this challenge, we develop a protocol to covalently immobilize labelled influenza A viruses on glass surfaces before exposing them to live epithelial cells . Our method extends the observation time for virus-plasma membrane association while minimizing viral modifications, facilitating live imaging of virus-cell interactions . Using single-molecule super-resolution microscopy, we investigate virus-receptor interaction showing that viral receptors exhibit reduced mobility at the virus-binding site, which leads to a specific local recepto...

Abstract Since 2020, large-scale outbreaks of highly pathogenic avian influenza (HPAI) H5N1 in Great Britain have resulted in substantial poultry mortality and economic losses. Alongside the costs, the risk of circulation leading to a viral reassortment that causes zoonotic spillover raises additional concerns. However, the precise mechanisms driving transmission between poultry premises and the impact of potential control measures in Great Britain, such as vaccination, are not fully understood. We have developed a spatial transmission model for the spread of HPAI in poultry premises calibrated to infected premises data for the 2022--23 season using Markov chain Monte Carlo . Our results indicate that enhanced biosecurity measures and/or vaccination of the premises surrounding an identified infected premises can substantially reduce the overall number of infected premises. Our findings highlight that enhanced control measures could limit the future impact of HPAI on the poultry industr...

{Excerpt} Time Period: April 13, 2025 - April 19, 2025 -- H5 Detection :  4 sites ( 1.0% ) -- No Detection :  406 sites ( 99.0% ) -- No samples in last week :  153 sites (...) Source: US Centers for Disease Control and Prevention,  https://www.cdc.gov/bird-flu/h5-monitoring/index.html?cove-tab=0 ____

A poultry farm in Quang Tri province. Source: WOAH,  https://wahis.woah.org/#/in-review/6440 ____

Abstract Highly pathogenic H5Nx influenza A viruses are causing unprecedented, season-independent outbreaks across avian and mammalian species, including dairy cattle, a novel reservoir. The sialoside-binding properties of influenza A hemagglutinin (HA) are strongly related to its ability to infect and transmit between hosts. Mucin-like O-glycans , omnipresent in respiratory tracts, have been understudied as viral receptors due to their complexity. To address this, we synthesized 25 O-linked glycans with diverse sialosides, including modifications by fucosides and sulfates. Our findings reveal that H5Nx 2.3.4.4b viruses uniquely bind core 3 sialyl-Lewisx and Sia-Gal-β3GalNAc, glycans not recognized by classical H5 or other avian viruses. By determining its crystal structure, we resolved the structural features of both structures in an H5 hemagglutinin (HA) from a 2016 2.3.4.4b virus. While these viruses do not bind human-type receptors , their promiscuous receptor specificity enhances ...