Influenza H6N8 Virus in Chicken and Mice

H6-subtype Avian Influenza viruses (AIvs) have a broader host range and circulate globally in wild birds, domestic ducks, geese, and terrestrial poultry all over the world.

Surveillance data have revealed that the predominant subtypes of H6 viruses were H6N1 and H6N2 prior to 2005. Since 2006, the isolation rate of the H6N6 subtype AIVs has begun to increase[1].

Their demonstrated capacity to adapt receptor-binding affinity for mammalian species constitutes a persistent concern for zoonotic transmission and public health.

In a recent study, a novel triple-reassortant H6N8 Influenza Virus strain was isolated from a chicken farm in southern China and designated as A/chicken/Guangdong/JM642/2023 (H6N8)[2].

Phylogenetic analysis indicated that this novel H6N8 virus was a triple-reassortant virus. It contains the HA gene derived from the Eurasian lineage, the NA gene from North American origin, and all six internal genes originating from H9N2 Avian Influenza viruses.

This novel virus possesses several key molecular determinants known to contribute to an expanded host range and increased virulence. Animal infection studies demonstrated that the virus was capable of infecting mice, even without prior adaptation. It replicated efficiently in the lungs and nasal turbinates, followed by systemic dissemination resulting in lethal outcomes. Inoculated chickens remained asymptomatic; however, the virus replicated efficiently in multiple organs, with high viral loads detected particularly in the lungs and kidneys. Viral shedding occurred via both the respiratory and digestive tracts, and horizontal transmission was observed among chickens. Notably, infected and contacted chickens developed high levels of antibodies from eight days post-inoculation (DPI) to the end of observation period.

This study enhances the understanding of the genetic and biological characteristics of the novel reassortant H6N8 Avian Influenza viruses, and underscores their potential risk to public health.

[1] Yan et al: Global distribution, receptor binding, and cross-species transmission of H6 influenza viruses risks and implications for humans in Journal of Virology – 2023. See here.
[2] Song et al: A Novel Recombinant Chicken-Derived H6N8 Subtype Avian Influenza Virus Caused Disease in Chickens and Mice in Viruses – 2025. See here.