Abstract
The spread of high pathogenic avian influenza virus (HPAIV) H5N1 clade 2.3.4.4b into Antarctica poses a major threat to polar wildlife. We report the detection of H5N1 in carcasses of eight species during the 2023-2024 and 2024-2025 austral summers in the South Shetland Islands: Antarctic shag, Antarctic tern, kelp gull, pintado petrel, Antarctic petrel, skuas, Antarctic fur seal, and southern elephant seal. Whole-genome sequencing, mutational profiling, and phylogenetic reconstruction revealed that the viruses detected in these hosts descended from distinct introduction events. One group of strains including complete and partial viral genomes from a gull, skuas, fur seals, an Antarctic tern, and a southern elephant seal clustered with H5N1 strains previously detected in marine mammals in South America and formed a polyphyletic lineage consistent with at least two independent introductions into Antarctica. A second group of strains including complete and partial viral genomes from petrels, shags, and skuas clustered with H5N1 strains previously detected in seabirds and marine mammals in South Georgia and with a previously reported HPAIV detection from Torgersen Island, Antarctic Peninsula. These findings reveal extensive epidemiological connectivity between South America and Antarctica, with South Georgia serving as a “stepping stone” for virus spread in the region.
Data availability
The sequencing data generated in this study have been deposited in the NCBI GenBank under the accession numbers OR910159, OR910186, OR910243, OR910261, OR910318, OR910371, OR910404, OR910447, OR910468, OR960980, OR960992, OR960998, OR961005, and OR979626. Additionally, the sequences were submitted to the EpiFlu database in GISAID (Global Initiative on Sharing Avian Flu Data) platform under the accession numbers listed in Table 1. The list of sequences used in the analyses and their corresponding accession codes and metadata are provided in Supplementary Data 2 and in the GISAID dataset EPI_SET_250923qb (https://doi.org/10.55876/gis8.250923qb). All other data supporting the findings of this study are included within the manuscript and its supplementary information files.
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Acknowledgements
Our sincere gratitude to the entire crew of the Polar Ship Admiral Maximiano (H-41), whose dedication was instrumental to the success of our activities, especially Commander Leandro Wanderley Rodrigues whose commitment to the sample collection operations was invaluable. We are thankful to the FIOANTAR Working Group, especially Sandra Soares and Lucia Marques, and the Vice-Presidency of Production and Innovation in Health (VPPIS). We are thankful for the viability to perform some experiments at the Biosafety Level 3 facility located at Oswaldo Cruz Institute. We also acknowledge the Global Initiative on Sharing All Influenza Data (GISAID) for the EpiFlu database, and other sequence databases which were used to share gene sequences and associated information. We would like to thank the financial support of Programa Antártico Brasileiro – PROANTAR, National Council for Scientific and Technological Development (CNPq/MCTIC/CAPES/FNDCT 440874/2023-8), Department of Science and Technology (DECIT), Brazilian Ministry of Health (MoH), Centro Latino-Americano de Biotecnologia (CNPq/CABBIO 423857/2021-5), CNPq PROEP-IOC 2024 (441699/2024-3). E.C.P. was supported by Programa INOVA (IOC/FIOCRUZ). CNPq productivity research fellowships support P.C.R. (311759/2022-0) and F.S.C. (304358/2024-0).
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M.O., M.L.B., B.R.P., R.V., F.S.C., B.P.G., A.S.M., C.M.R., L.M., M.M., and D.M. participated in carcasses and sample collection. M.O., E.C.P., E.C., L.C.J., J.O.M., L.M., L.R.A., U.J.B.S., and I.A. performed experiments and analysis. P.C.R., M.M.S., F.C.M., F.S.C., provided conceptual advice. M.O. and R.E.T.V. analyzed the results, prepared illustrations, and wrote the manuscript draft. L.T., W.D., M.M.S., F.S.C., L.T., and W.D. provided resources and edited the manuscript. All authors contributed to the manuscript review and approved the final version of the manuscript. All authors contributed to data interpretation and provided feedback on the manuscript.
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Ogrzewalska, M., Vanstreels, R.E.T., Pereira, E.C. et al. Genomic analysis of high pathogenicity avian influenza viruses from Antarctica reveals multiple introductions from South America. Nat Commun (2026). https://doi.org/10.1038/s41467-026-71544-3
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DOI: https://doi.org/10.1038/s41467-026-71544-3