Correct! The hepatic intranuclear inclusion bodies are due to psittacine beak and feather disease (PBFD) virus infection. If you got the correct answer on the first try, congratulations!

The diagnostic opinions, based on examination of H&E stained tissue sections, were varied on this case. The two most likely differentials include avian adenovirus and psittacine beak and feather disease (PBFD) virus infections.

Below (Figure 6) are the in situ hybridization results using a PBFD viral-specific digoxigenin-labeled DNA probe. Deposition of a blue-black chromagen identifies the formation of DNA hybrids (a positive result). Also presented is a transmission electron micrograph of the affected skin in this bird (Figure 7). Notice the non-membrane bound dense paracrystalline arrays typical of circovirus inclusions.

This case emphasizes that a tentative or differential diagnosis of viral infections can be made on H&E-stained tissue sections alone. However, definitive diagnosis of viral infection should be made by more specific detection methods. This is particularly important in multiple bird situations, where the treatment and prognosis of the virus infection can vary greatly and control or treatment of the disease is of immediate concern.

Figure 6. DNA in situ hybridization testing of the liver section with a PBFD-specific, digoxigenin labeled oligonucleotide probe. A positive reaction results in deposition of the blue-black chromagen. DNA in situ hybridization with fast green counterstain, magnification = 1,000X.

Figure 7. Transmission electron micrograph of PBFDV-infected skin of this bird. Notice the non-membrane bound, paracrystalline arrays typical of circoviral inclusions. Uranyl acetate and lead citrate stain, magnification = 203,850X.

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