PREreviews of “Emergence and Evolution of Triple Reassortant Highly Pathogenic Avian Influenza A(H5N1) Virus, Argentina, 2025”

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Emergence and Evolution of Triple Reassortant Highly Pathogenic Avian Influenza A(H5N1) Virus, Argentina, 2025

by Estefania Benedetti, Maria Carolina Artuso, Alexander M. P. Byrne, Maria de Belen Garibotto, Martín Avaro, Luana Erica Piccini, Ariana Chamorro, Marcelo Sciorra, Vanina Daniela Marchione, Mara Laura Russo, Maria Elena Dattero, Erika Macias Machicado, Monica Galiano, Nicola Lewis, and Andrea Veronica Pontoriero

Posted: December 10, 2025
Server: Preprints.org
DOI: 10.20944/preprints202512.0962.v1

Abstract

The H5N1 subtype of highly pathogenic avian influenza (HPAI) poses a major zoonotic threat due to its high fatality rate and capacity for cross species transmission. In early 2025, Argentina detected a novel triple reassortant A(H5N1) virus in Chaco Province, combining Eurasian, North American, and South American lineage segments. Genomic analyses of subsequent outbreaks in Buenos Aires and Entre Ríos confirmed persistence of this reassortant and additional HA substitutions (T204K, P251S) potentially linked to increased mammalian receptor affinity. Although PB2 sequences lacked canonical mammalian-adaptive markers (E627K, Q591K, D701N), all contained I292M, a mutation associated with human adaptation. Phylogenetic analyses revealed distinct genotypes and increasing divergence. These findings indicate ongoing viral evolution and adaptation within Argentina, emphasizing the urgent need for sustained genomic surveillance, timely data sharing, and integrated One Health strategies to mitigate zoonotic and socioeconomic risks associated with H5N1 spread in South America.

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PREreviews of Emergence and Evolution of Triple Reassortant Highly Pathogenic Avian Influenza A(H5N1) Virus, Argentina, 2025

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