The Pathogenesis of Proventricular Dilatation Disease Caused by Parrot Bornaviruses: A Possible Role For Neuropeptide Y (Npy)

Abstract

Background Psittacine Bornaviruses cause a unique disease syndrome in parrots and related birds. Known as proventricular dilatation disease (PDD), it is characterized by massive dilatation of their proventriculus as a result of excessive food accumulation within that organ. This leads to gastric obstruction and eventually, to death by starvation. Results In a preliminary study on the transcriptome of psittacine bornavirus-infected human astroglia it was noted that the gene encoding neuropeptide Y was significantly upregulated. In a subsequent study of cockatiels experimentally infected with the same strain of psittacine bornavirus, their brains were examined by RNA-seq to determine which genes were being actively transcribed. It was confirmed that among the genes whose expression was significantly increased relative to control, uninfected birds was that for neuropeptide Y. Conclusions Neuropeptide Y is known to cause overeating in birds. We hypothesize therefore that the clinical manifestations of proventricular dilatation disease are a result of the excessive production of neuropeptide Y by bornavirus-infected brain cells acting in association with damage to the neurons of the proventricular myenteric plexus.

Cannabinoid receptor 2 evolutionary gene loss makes parrots more susceptible to neuroinflammation

“…The same pattern has been detected across all investigated parrot species, suggesting that parrots in general may be more vulnerable to neuroinflammation than other birds. This is supported by the fact that parrots are exceptionally susceptible to bornavirus-related neuropathy [8,82–84] and also other parrot pathogens including bacteria, viruses and fungi are suspected to frequently cause behavioural disorders [85–87].…”

“…Surprisingly, similar psychological (in animals referred to as behavioural) disorders have been frequently recognized in some cognitively advanced animals, namely the parrots [3–5]. Like in human depression, in parrots symptoms like anxiety, apathy, over-eating, indifference and self-damage (feather plucking) are observed and diagnosed by veterinarians [6–8]. While in parrots little is presently known about the possible causes of the behavioural disorders, in humans they have been recently linked with neural inflammation [9].…”

Revealing genomic changes responsible for cannabinoid receptor loss in parrots: mechanism and functional effects

“…The same pattern of increased proinflammatory signalling (IL1B expression) in the brain during peripheral inflammation was detected in both budgerigars and other parrot species, suggesting that parrots in general may be more vulnerable to neuroinflammation than other birds. This is supported by the fact that parrots are exceptionally susceptible to bornavirus-related neuropathy (Rinder et al 2009;Staeheli et al 2010;Rubbenstroth et al 2012;Chen et al 2020).…”