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Apparent resolution of parrot bornavirus infection in cockatiels (Nymphicus hollandicus)

Authors Murray O, Turner D, Streeter K, Guo J, Shivaprasad HL, Payne S, Tizard I

Received 17 February 2017

Accepted for publication 17 March 2017

Published 6 July 2017 Volume 2017:8 Pages 31—36


Checked for plagiarism Yes

Review by Single-blind

Peer reviewer comments 3

Editor who approved publication: Professor Young Lyoo

Olivia Murray,1 Debra Turner,1 Kristen Streeter,1 Jianhua Guo,1 HL Shivaprasad,2 Susan Payne,1 Ian Tizard1

1Schubot Exotic Bird Health Center, Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX, 2California Animal Health and Food Safety Laboratory System, University of California, Tulare, CA, USA

Abstract: Parrot bornavirus (PaBV), the etiologic agent of proventricular dilatation disease (PDD), is a major cause of concern in the avian health community. Within an infected flock, some birds will develop PDD and succumb to disease, while others remain healthy. Until now, there has been no study describing the results of long-term infection in apparently healthy carriers. For the last 5 years, the Schubot Exotic Bird Health Center at Texas A&M University has monitored individual PaBV shedding data in a flock of 66 naturally infected cockatiels. Of these birds, 53 were detected shedding PaBV4 in their droppings by reverse transcriptase polymerase chain reaction on at least one occasion. However, the prevalence of shedding declined over time, with the last positive cloacal swab being in October 2013. To determine whether the decline and eventual lack of shedding was an indication of virus elimination, seven previously shedding birds were euthanized and necropsied in 2016. Neither any gross lesion of PDD was observed nor was there any evidence of PDD or bornaviral encephalitis detected by histopathology. All tissues tested were negative for the presence of PaBV by reverse transcriptase polymerase chain reaction and immunohistochemistry. Thus, there was no evidence of an ongoing, productive infection in these birds. There are two possible explanations for these results. One possibility is that the birds were previously infected and have subsequently eliminated the virus. Alternatively, there may have been as few as three truly infected birds in the flock and the transient detection of PaBV in the droppings of other birds may simply be a “pass-through” phenomenon.

Keywords: cockatiel, immunohistochemistry, parrot bornavirus, polymerase chain reaction, proventricular dilatation disease

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