Avian bornavirus genotype 4 recovered from naturally infected psittacine birds with proventricular dilatation disease in South Africa

Robert D Last,Herbert Weissenböck,H.L Shivaprasad,Nora Nedorost

doi:10.4102/jsava.v83i1.938

Abstract

The occurrence of proventricular dilatation disease caused by avian bornavirus (ABV) in captive psittacine birds has long been suspected in South Africa. This report documents the first detection by polymerase chain reaction and gene sequence analyses of ABV from three clinical cases of proventricular dilatation disease (PDD) in captive bred blue and gold macaws (Araara rauna) resident in this country. Lymphoplasmacytic encephalitis, gastrointestinal myenteric gangioneuritis and leiomyositis were the most prominent histopathological changes and ABV genotype 4 was detected in tissues from all three birds. Immunohistochemical stains for ABV antigen revealed positive labelling of neurons and glial cells of the brain, myenteric ganglia and nerve fibres as well as smooth muscle cells of the gastrointestinal tract of all three birds. In one bird, positive labelling of the peripheral nerves was observed. The identical sequence of the analaysed genome fragment of all three samples, history that all of these birds had originated from the same breeding facility, and young age at presentation raise the question of possible vertical transmission.

Highlights

Avian bornaviruses are a recently identified genetically heterogeneous group of representatives of the Bornaviridae family which are currently divided into at least 7 genotypes (Hoppes et al 2010; Payne et al 2011). These viruses – it is still not finalised whether they will be classified as different species or different genotypes or genogroups of a single virus species – are associated with proventricular dilatation disease (PDD), predominantly but not exclusively in psittacine birds (Gancz, Clubb & Shivaprasad 2010; Gancz et al 2009; Gray et al 2010; Honkavuori et al 2008; Hoppes et al 2010; Kistler et al 2008; Weissenböck et al 2009a)
Avian bornavirus has to date been documented in more than 80 species of psittacine birds as well as several other avian species (Delnatte et al 2011; Gancz et al 2010; Gray et al 2010; Hoppes et al 2010; Weissenböck et al 2009b; Wünschmann et al 2011)
Proventricular dilatation disease has been previously reported in South Africa, the implicated avian bornavirus was not identified in any of these cases (Gancz et al 2010)

Summary

Introduction

Avian bornaviruses are a recently identified genetically heterogeneous group of representatives of the Bornaviridae family which are currently divided into at least 7 genotypes (Hoppes et al 2010; Payne et al 2011). Proventricular dilatation disease is a usually fatal disease of birds with worldwide occurrence, which is characterised by lymphoplasmacytic cell infiltrates into the central, peripheral and autonomic nervous systems and in some cases various visceral organ sites (Gancz et al 2010; Hoppes et al 2010; Kistler et al 2010; Lierz et al 2009; Ouyang et al 2009; Wünschmann et al 2011).

Results

Conclusion