Emerging Microbes & Infections | 2025
29 October 2025
A new study published in Emerging Microbes & Infections investigates recent outbreaks of H5N1 avian influenza virus infections in tigers in Vietnam. The researchers collected samples from dead tigers in Vietnam between August and October 2024 and performed whole-genome sequencing. Phylogenetic analysis revealed that these H5N1 strains belonged to clade 2.3.2.1e, closely related to lineages causing ongoing human infections in Cambodia. Notably, the tiger-infecting viruses carried mutations such as E627K in the PB2 gene, known to enhance mammalian host adaptation, and additional amino acid substitutions associated with increased transmissibility and pathogenicity in mammals.
The study concludes that the H5N1 viruses infecting Vietnamese tigers originated from lineages circulating among poultry and humans in the region, with mutations suggesting enhanced capability to infect mammals.
