Pathogenicity and transmissibility of a highly pathogenic avian influenza virus H5N6 isolated from a domestic goose in Southern China.

Since the first outbreak of H5N6 reported in Laos at 2013, there has been a dramatic increase in H5N6 strains isolated from waterfowl in China, particularly Southern China. However, pathogenicity and transmissibility of the virus in different birds remain largely unknown. In this study, a novel H5N6 virus, termed QY01, that belonged to group C in 2.3.4.4 was isolated from an apparently healthy domestic goose in Guangdong province, southern China in 2016. In order to simulate the natural transmission of different kinds of birds, we evaluated its pathogenicity and transmissibility in chickens, domestic geese and pigeons. To investigate the replication and shedding of QY01 in poultry, chickens, geese and pigeons were inoculated intranasally with 106 EID50 of virus. In addition, to measure intra-species transmission of QY01, three sentinel birds were housed with each group. The results demonstrated that QY01 exhibited a highly pathogenic phenotype, and was transmissible among in chickens and geese. However, the virus did not appear to be pathogenic in pigeons, indicating that this novel H5N6 virus exhibited different host ranges and tissue tropisms, and may pose a substantial risk for the chicken and goose industry. Therefore, continued surveillance for H5N6 AIVs is necessary, and increased attention should be paid to cross-species transmission between waterfowl and terrestrial birds.