Adenovirus of psittacine birds: investigations on isolation and development of a real-time polymerase chain reaction for specific detection.

Liver samples of psittacine birds with a histological suspicion of an adenovirus infection, confirmed by electron microscopy examination, were subjected to virus isolation attempts using a heterologous cell culture system and a homologous cell culture system in the form of chicken embryo liver cells and psittacine embryo fibroblasts, respectively. Whereas isolation in chicken embryo liver cells failed, virus was isolated successfully in the psittacine embryo fibroblasts cell culture system. Molecular investigations identified the virus as a specific psittacine adenovirus (PsAdV). Additionally, on the basis of the hexon gene sequence data obtained, a real-time polymerase chain reaction (PCR) for specific detection of PsAdV was developed. To ensure an exclusive hybridization with PsAdV, selected primers were located within the variable L1 region of the hexon gene. Furthermore, the specificity of the real-time PCR was confirmed by investigation of a panel of different avian adenoviruses and unrelated DNA viruses. Using this PCR, the threshold cycle values obtained support the propagation of PsAdV in the homologous cell culture system in comparison with the chicken cell culture system. Moreover, the developed PCR represents a reliable method for specific and sensitive detection of PsAdV in clinical samples.