Parrot Bornavirus Infection and Proventricular Dilatation Disease in Hungary: New Data and Application of Novel Diagnostic Methods

Proventricular dilatation disease (PDD), a chronic wasting disease of mainly large parrots, is well-known for its miscellaneous and fatal nature in avian practice since the 1970s. The most remarkable signs of the disease are regurgitation, passing of undigested seeds in the feaces, weight loss although having increased appetite. Seizures, behavioral changes, and ataxia can be detected if the disease involves the central nervous system. The disease can also be called as Avian Ganglioneuritis (AG) after the major histopathological lesions characterizing both of the clinical manifestations (Rossi et al., 2018). The etiology has long been unknown, but the latest years pyrosequencing of organ samples originated from diseased birds, revealed a bornavirus (Honkavuori et al., 2008). The pathomechanism of the diseases caused by avian bornaviruses (ABV) is not entirely clear yet and the diagnostic methods are still to be refined. Previous studies prove that avian bornaviruses are present in Hungary and they may cause significant losses in parrot collections (Weissenböck et al., 2009, Bakonyi et al., 2010). With this study, we gained further data on the occurrence of the virus, using new diagnostic methods. In the present investigation, the sensitivity of reverse transcription polymerase chain reaction (RT-PCR) done with RNA yielded from the feather calami samples (F) was compared to the RT-PCR done with the vastly used cloacal swab samples (C). Furthermore, we performed a serological test using ELISA method, validated to detect anti-ganglioside antibodies produced during the progress of PDD (Rossi et al., 2008). The results of this test can inform us about the neuropathy before the appearance of the major clinical signs. According to researches conducted with a significant number of samples from western and southern European aviaries, the prevalence of ABV infection can be as high as 22,8% in asymptomatic collections (Heffels-Redmann et al., 2011). Considering the high prevalence, the minimally invasive methods to collect samples are essential to diagnose the infection in large bird flocks.