Two epidemics, one genotype, different outcomes: evolutionary changes of Avian Influenza H5N1, genotype EA-2024-DI

作者：Bianca Zecchin, Isabella Monne, Marta Dianati, Alessio Bortolami, Enrico Savegnago, Erga Shkodra, Sandra Revilla Fernandezd, Mieke Steensels, Steven Van Borm, Emiliya Ivanova, Ivana Rončević, Vladimir Savić, Alexander Nagy, Charlotte K. Hjulsager, Casper Thorup, Lars E. Larsen, Imbi Nurmoja, Ari Kauppinen, Tammiranta, François‐Xavier Briand, Béatrice Grasland, Ann Kathrin Ahrens, Anne Pohlmann, Anne Gunther, Timm Harder, Péter Malik, Laura Garza Cuartero, Svetlana Cvetkova, Juris Kibilds, Žanete Šteingolde, Egidijus Pumputis, Simona Pilevičienė, Chantal J. Snoeck, Manon Bourg, Oxana Groza, Beatriz Bellido Martin, Ron Fouchier, Sanne Thewessen, Oanh Vuong, Monika Ballmann, M.Y. Engelsma, Cathrine Arnason Bøe, Anna Pikuła, Krzysztof Smietanka, Margarida Duarte, Margarida Henriques Mourao, Iuliana Onita, Dejan Vidanović, Zuzana Dirbáková, M. Tinák, Brigita Slavec, Marı́a José Ruano, Maite Barrios, Fereshteh Banihashem, Caroline Bröjer, Stina Hedblom, Siamak Zohari, Claudia Bachofen, Ashley C. Banyard, Holly A. Coombes, Ben Clifton, Benjamin C. Mollett, Joe James, Michael McMenamy, Robyn McKenna, Ken Lemon, Calogero Terregino, Alice Fusaro · 发表于：bioRxiv (Cold Spring Harbor Laboratory) · 年份：2026 · DOI：10.64898/2026.05.25.727580 · 研究领域：Influenza Virus Research Studies、Identification and Quantification in Food、Livestock and Poultry Management

Since 2020, high pathogenicity avian influenza H5Nx viruses of clade 2.3.4.4b have become enzootic in Europe, causing recurrent epidemic waves characterized by extensive reassortment events. Here, we describe the emergence of a single high-fitness genotype (EA-2024-DI) that has driven two consecutive waves, evolving into distinct sub-lineages. While its circulation is ongoing, during the 2025-2026 wave it caused an unprecedented number of cases in wild birds. Using phylodynamic analyses of a large dataset of genomic sequences, we compared the spatial diffusion and host transmission pattern of the EA-2024-DI sub-lineages across the three most recent epidemic waves (2023-2024, 2024-2025 and 2025-2026). We show that the genotype has persisted over time and has spread primarily through wild Anseriformes, but with a marked change in the transmission patterns between the different waves and a shift in the epicenter from Eastern to Central Europe, the latter having emerged as an important hub for virus diffusion throughout Europe. Our results reveal a recent increase in the frequency of viruses from wild and domestic mammals carrying mutations enhancing virus replication in mammalian hosts, highlighting the importance of proactive monitoring of this group of hosts to better understand its role in the virus ecology and evolution.