Avian Orthobornavirus Study Guide

Overview and Clinical Importance

Avian orthobornaviruses are neurotropic RNA viruses belonging to the family Bornaviridae within the order Mononegavirales. These viruses are the causative agents of Proventricular Dilatation Disease (PDD), also known as macaw wasting disease, avian ganglioneuritis, or neuropathic gastric dilatation. PDD is a chronic, progressive, and often fatal neurological disease that primarily affects psittacine birds (parrots) worldwide.

First recognized in the late 1970s in imported macaws in the United States and Germany, the causative agent remained unknown for three decades until 2008, when two independent research groups identified avian bornavirus through advanced molecular techniques. PDD has since been reported in more than 80 species of psittacine birds across all continents, representing a significant threat to captive breeding programs, zoological collections, and endangered species conservation efforts.

Etiology and Taxonomy

Viral Classification

Avian bornaviruses are enveloped, non-segmented, single-stranded negative-sense RNA viruses. Following taxonomic revisions, the original term "avian bornavirus" has been replaced by specific virus names classified into distinct viral species within the genus Orthobornavirus.