Histopathology and the detection of avian bornavirus in the nervous system of birds diagnosed with proventricular dilatation disease

Abstract

Avian bornavirus (ABV) is currently considered a probable etiologic agent of proventricular dilatation disease (PDD) of psittacines. We tested 24 stored avian brain samples, processed for histopathology and retained following their submission for necropsy or histopathology to the Schubot Exotic Bird Center diagnostic laboratory in 1992. Thirteen of these samples were from birds diagnosed at that time as suffering from PDD. The remaining 11 samples were diagnosed as suffering from diseases other than PDD. Immunohistochemistry was performed using an antiserum directed against the ABV nucleoprotein (Nprotein). Stained slides were read by an investigator unaware of their prior histopathology results. Cells containing ABV N-protein were present in the nervous tissues of all 13 PDD cases. One bird not previously diagnosed with PDD also had ABV N-protein in its brain. A review of this bird's necropsy report indicated that it was, most probably, also suffering from PDD. The remaining 10 non-PDD birds had no detectable Nprotein in their brains. The N-protein was present in the cerebrum, cerebellum and spinal cord. These findings support other studies that indicate that ABV is an etiological agent of PDD.

Occurrence of avian bornavirus infection in captive psittacines in various European countries and its association with proventricular dilatation disease

“…In PDD-affected dead psittacine birds ABV RNA was demonstrated not only in the nervous system and the gastrointestinal tract but in nearly all other tissues (Kistler et al, 2008;Honkavuori et al, 2008;Lierz et al, 2009;Rinder et al, 2009;Villanueva et al, 2009;Enderlein et al, 2009;Gray et al, 2010;Kistler et al, 2010;Raghav et al, 2010). Further methods for the direct detection of ABV in dead birds as well as in crop biopsies are immunohistochemistry (IHC) Ouyang et al, 2009;Weissenbö ck et al, 2009a;Herzog et al, 2010;Raghav et al, 2010), virus isolation in the quail cell lines CEC-32 and QM7 or duck embryo fibroblasts (Gray et al, 2010), and in situ hybridization (Weissenbö ck et al, 2010). In live birds, ABV can be diagnosed directly by detection of ABV RNA using RT-PCR in faeces, swabs of crop and cloaca, and blood Lierz et al, 2009;Enderlein et al, 2009;Gray et al, 2010;Kistler et al, 2010).…”

Diagnosis of Avian bornavirus infection in psittaciformes by serum antibody detection and reverse transcription polymerase chain reaction assay using feather calami

“…The recent identification of ABV as the cause of PDD 19,21 has resulted in the need for diagnostic tests based on the presence of bornaviral RNA, protein, and anti-bornaviral antibodies for identifying birds infected with ABV. 9,23,29 Since the disease is considered to be a major threat to captive psittaciform populations, accurate diagnosis using non-or minimally invasive procedures is important in order to identify infected birds and isolate them from uninfected individuals.…”

“…In birds, the virus can be detected in many tissues, including the central nervous system. 9,23,29,33 The genome of ABV consists of a nonsegmented negative single-strand RNA component of approximately 9,000 nt. Due to its recent discovery, ABV has not been fully characterized.…”

Indirect Immunofluorescence Assay for Intra Vitam Diagnosis of Avian Bornavirus Infection in Psittacine Birds

“…The presence of viral antigen was demonstrated in the brain, spinal cord, retina, myocard, proventriculus, and gizzard. Histopathologically, in all six psittacines characteristic PDD lesions consisted of nonpurulent meningoencephalitis, myelitis, neuritis, myocarditis, and/or ganglionitis in the gastrointestinal tract (9).…”