The isolation, pathogenesis, diagnosis, transmission, and control of avian bornavirus and proventricular dilatation disease

Abstract

Proventricular dilatation disease (PDD) is a common infectious neurologic disease of birds comprising a dilatation of the proventriculus by ingested food as a result of defects in intestinal motility, which affects more than 50 species of psittacines, and is also known as Macaw wasting disease, neuropathic ganglioneuritis, or lymphoplasmacytic ganglioneuritis. Definitive diagnosis of PDD has been problematic due to the inconsistent distribution of lesions. Since its discovery, avian bornavirus (ABV) has been successfully cultured from the brains of psittacines diagnosed with PDD, providing a source of antigen for serologic assays and nucleic acid for molecular assays. This article provides evidence that ABV is the etiologic agent of PDD. Recent findings on the transmission, epidemiology, pathogenesis, diagnosis, and control of ABV infection and PDD are also reviewed.

Fig. 1

Dilated proventriculus in a blue and gold macaw, PCR-positive for ABV, with histopathological lesions of PDD.

Fig. 2

Immunofluorescence photomicrograph of cultured duck embryo fibroblasts infected with an ABV isolate from a yellow-collared macaw 3 days previously. The lack of apparent cytotoxicity and presence of speckled nuclear fluorescence is typical of bornavirus infection. (Immunoflorescense stain at 10X.)

Fig. 3

Negatively stained (with phosphotungstic acid [PTA]), virus-like particle (83 nm in diameter) from the eye fluid of an Eclectus parrot with confirmed PDD and ABV infection. The image was recorded with an FEI Morgagni 268 transmission electron microscope at a magnification setting of 180,000X.

Fig. 4

The amino acid sequence of a 438 kDa protein isolated from the eye fluid of an Eclectus parrot. The colored sequences are the peptides shown to be identical to ABV N-protein.

Fig. 5

Severe PDD lesions in the ventriculus of experimentally infected cockatiels.