新型H6亚型禽流感病毒对鸡的致病性和传播性研究OA

Since October 2025,suspected avian influenza cases have been successively reported in chicken flocks across several provinces in Eastern China.Affected chickens included yellow-feathered broilers,white-feathered broilers,and laying hens,with severe respiratory signs as the main clinical manifestation and an acute decline in egg production in laying hens.In this study,pathogen isolation,identification,and phylogenetic analyses were performed using samples collected from two typical affected farms,followed by regression experiments in specific-pathogen-free(SPF)laying hens.The results showed that the viruses isolated from two farms were H6N2 and H6N1 subtype avian influenza viruses(AIV),respectively.Phylogenetic analysis indicated that both isolates were novel reassortants derived from waterfowl-origin ST339-like lineage H6 subtype AIV and chicken-origin G57-genotype H9N2 subtype AIV.Both H6 viruses were highly adaptive to chickens,inducing typical respiratory symptoms and reduced egg production.Viral shedding through the oropharynx and cloaca,with a maximum duration of 8 days.Viral titer detection revealed efficient replication of the viruses in the respiratory tract and eyelid tissues,as well as high-level replication in the oviduct and kidney of some infected chickens.Transmissibility experiments demonstrated that both the H6N1 and H6N2 strains could be efficiently transmitted through directed contact among SPF laying hens,and the H6N2 strain could airborne transmission within flocks.These findings suggest that the novel reassortant H6 subtype AIV carrying H9N2 internal genes have enhanced adaptability to chickens and pose a potential epidemic risk.Targeted epidemiological surveillance and the establishment of scientific and effective prevention and control systems are urgently required to prevent epidemic spread and safeguard the poultry industry.