Genetic characterization of fowl adenoviruses isolated from chickens with hydropericardium syndrome in Japan.

We genetically characterized fowl adenoviruses (serotype 4 FAdV, FAdV-4) isolated from chickens with hydropericardium syndrome (HPS) in Japan by the polymerase chain reaction (PCR) method coupled with direct sequencing. Phylogenetic analysis based on the part of the hexon gene that included the L1 region revealed that all FAdV-4 isolates from chickens with HPS in Japan were identical and were distinguished completely from the cluster including FAdV strains from chickens with HPS in India and Pakistan. This suggested that FAdV-4 from the HPS chickens in India and Pakistan was derived from a common ancestor, but the origin of the FAdV-4 from the HPS chickens in Japan was completely different.