Comparison of the diagnostic methods on the canine adenovirus type 2 infection

Background and aims: Canine adenovirus type 2 (CAV-2) infection is typically diagnosed histopathologically since intranuclear inclusion bodies (IN/IBs) are demonstrable in the infected lung. However, it is sometimes difficult to identify IN/IBs, particularly in autolyzed tissues or samples from both early and late stages of infection, and other methods were presently developed. Methods: Stray dog samples were evaluated by histopathology, polymerase chain reaction (PCR), and immunohistochemistry (IHC) to investigate the status of the CAV-2 infection on the stray dogs in Korea. Histologic tests were performed, and dogs with pneumonic lungs were further evaluated by IHC and PCR. Results: Pathognomonic IN/IBs were identified in 3 of 213 lungs; CAV-2 PCR was positive for 27 of 213 pneumonic lungs. A total of 7 of 27 CAV-2 PCR-positive lungs were IHC-positive. No PCR-negative lung was IHC-positive. Positive results were primarily detected in the IN/IBs of the bronchial epithelial cells, macrophages, and very rarely in the cytoplasm of bronchial epithelial cells. Conclusions: IHC was a more reliable diagnostic method than conventional pathologic methods in the present study, and suggests that IHC should be routinely used in the diagnosis of CAV-2 infection. Further, PCR alone may not be adequate for CAV-2 diagnosis.