Variant Serotypes of Fowl Adenovirus Isolated from Commercial Poultry Between 2007 and 2017 in Some Regions of China.

The present study was performed to detect and characterize the serotypes of fowl adenovirus associated with inclusion body hepatitis (IBH) or hepatitis-hydropericardium syndrome (HHS) in commercial poultry in some regions of China between 2007 and 2017. Approximately 81 fowl adenovirus strains were isolated from liver or kidney samples from diseased poultry. A sequencing analysis of the hexon loop 1 gene revealed fowl adenovirus serotypes 8a, 8b, and 11 in samples of broilers with IBH, serotype 11 in layers with IBH, and serotype 4 in poultry with HHS. Of the fowl adenovirus serotype 4 strains, 62.07% were isolated from layers. Additionally, 74.07% of the isolated strains were fowl adenovirus serotype 11 prior to June 2014; 53.70% were serotype 4 after that time point; and strains isolated in the first half of 2017 were all serotype 8b, which was related to the widespread application of inactivated serotype 4 adenovirus vaccines. These results demonstrate that fowl adenovirus serotypes 11, 4, and 8b were the predominant serotypes in some regions of China between 2007 and June 2014, between June 2014 and 2016, and in the first half of 2017, respectively. Layers were the predominant host infected with fowl adenovirus serotype 4 and could also be infected by serotype 11.