Characterization of fowl adenoviruses isolated between 2007 and 2014 in China

Forty-three fowl adenovirus (FAdV) strains were isolated in China from 2007 to 2014 from poultry and ostriches with inclusion body hepatitis (IBH) and hydropericardium syndrome (HPS). Phylogenetic analysis showed that 28/43 strains clustered into Fowl aviadenovirus D (FAdV-D) and 9/43 strains clustered into FAdV-E. FAdV-C included three isolates of ostrich origin, one of goose origin and two of chicken origin. Based on hexon loop 1 gene sequencing analysis, these viruses were genetically related to FAdV-4, FAdV-8a, FAdV-8b and FAdV-11, of which FAdV-11 was dominant. The isolation in 2014 of three FAdV strains belonging to serotype 4 from ostrich flocks is to our knowledge the first finding of FAdV-4 infection and HPS cases in ostriches. Epidemiological analysis showed that FAdV has been circulating in northern and eastern China, where more than 50% of layers and broilers are raised. The hosts of this pathogen included broilers, layers, geese and ostriches. IBH and HPS cases had a sporadic or cluster distribution from 2007 to 2013; however, since 2014 the number of cases has increased sharply. To control FAdV, strict biosecurity protection measures are necessary and a multivalent vaccine may be needed.