Occurrence of avian bornavirus infection in captive psittacines in various European countries and its association with proventricular dilatation disease.

Clinic for Birds, Reptiles, Amphibians and Fish, Faculty of Veterinary Medicine, Justus Liebig University Giessen, Frankfurter Strasse 91-93, D-35392, Giessen, Germany.
Avian Pathology (Impact Factor: 1.73). 08/2011; 40(4):419-26. DOI: 10.1080/03079457.2011.589825
Source: PubMed

ABSTRACT A total of 1442 live birds and 73 dead birds out of 215 bird collections in Spain, Germany, Italy, the UK and Denmark were tested for avian bornavirus (ABV) infection by four different methods. The majority of the birds were psittacines belonging to 54 different genera of the order Psittaciformes. In total, 22.8% of the birds reacted positive for ABV in at least one of the tests. Combined testing of swabs from the crop and cloaca, and serum for the diagnosis of ABV infection in live birds revealed that virus shedding and antibody production coincided in only one-fifth of the positive birds so that the examination of these three samples is recommended for reliable ABV diagnosis. By statistical analysis of this large number of samples, the ABV infection proved to be highly significant (P <0.001) associated with histopathologically confirmed proventricular dilatation disease (PDD) in dead birds as well as with clinically assumed PDD in live birds. However, ABV infection was also detected in psittacines without pathological lesions or clinical signs of PDD. Twelve non-psittacine birds belonging to the genera Aburria, Ciconia, Geopelia, Leucopsar and Pavo were tested negative for ABV infection. Within the order of Psittaciformes, birds belonging to 33 different genera reacted positive for ABV. In 16 of these psittacine genera, the ABV infection was demonstrated for the first time. The present study emphasizes the widespread occurrence of clinically variable ABV infections in Europe by analysing a large number of specimens from a broad range of bird species in several assays.

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    ABSTRACT: To study the course of natural avian bornavirus (ABV) infection, 63 psittacines of three bird collections where ABV had been demonstrated were investigated over a period of 1 yr. The psittacines were clinically observed and swabs of crop and cloaca as well as serum samples were collected three separate times at intervals of 2-6 mo. According to the results of detection of ABV RNA by reverse transcriptase polymerase chain reaction (RT-PCR) and of anti-ABV antibodies by indirect immunofluorescence assay (IIFA), 43 of the birds were found to be infected with ABV. Based on variations in virus shedding and antibody production in combination with the occurrence of proventricular dilatation disease (PDD) -related clinical signs, pathological findings, and lethal outcome, four different groups of infected psittacines and a fifth group of noninfected psittacines were identified. Group 1 comprised six birds with various courses of ABV infection and forms of clinical PDD. Groups 2-4 included all birds with subclinical ABV infections: Group 2 contained 13 birds that were consistently (subgroup A, 6 birds) or inconsistently (subgroup B, 7 birds) ABV positive by PCR and serology; group 3 was composed of 13 psittacines exhibiting only anti-ABV antibodies; and 8 birds that had positive ABV RNA detection in crop and cloaca, but did not develop anti-ABV specific antibodies, were classified in group 4. Twenty-three out of the 63 psittacines remained free of detectable ABV RNA or anti-ABV antibodies over the whole observation period (group 5). Based on the results, it seems that birds with high ABV RNA load in crop and cloaca combined with high anti-ABV antibodies have a high risk of the development of PDD, indicating that the humoral antibodies do not protect against the disease. The meaning of the detection of ABV RNA and antibodies at a low and inconsistent level for the single bird as well as for the epidemiology of the ABV infection remained unclear in this field study and needs to be further investigated.
    Avian Diseases 03/2012; 56(1):153-9. · 1.73 Impact Factor
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    ABSTRACT: Avian bornavirus (ABV) is the presumed causative agent of proventricular dilatation disease (PDD), a major fatal disease in psittacines. However, the influencing factors and pathogenesis of PDD are not known and natural ABV infection exhibits remarkable variability. We investigated the course of infection in 18 cockatiels that were intracerebrally and intravenously inoculated with ABV. A persistent ABV infection developed in all 18 cockatiels, but, as in natural infection, clinical disease patterns varied. Over 33 weeks, we simultaneously studied seroconversion, presence of viral RNA and antigens, infectious virus, histopathologic alterations, and clinical signs of infection in the ABV-infected birds. Our study results further confirm the etiologic role of ABV in the development of PDD, and they provide basis for further investigations of the pathogenetic mechanisms and disease-inducing factors for the development of PDD.
    Emerging Infectious Diseases 02/2012; 18(2):234-41. · 6.79 Impact Factor
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    ABSTRACT: TO THE EDITOR: Proventricular dilatation disease (PDD) is a fatal disease in psittacines that jeopardizes critical species conservation projects, such as that involving the Spix's macaw (Cyanopsitta spixii), the world's most endangered bird species (1). The disease is characterized by lymphoplasmacytic infiltrations in the enteric and central nervous systems (2). Consequently, gastrointestinal and neurologic disorders are the major clinical manifestations. Only recently has the cause of the disease been identified by characterization of a newly discovered member of the family Bornaviridae, the avian bornavirus (ABV), which has been detected in affected psittacines (3,4). The relationship of an infection with ABV and the occurrence of PDD has been described in natural cases (5,6) and in experimental trials (7,8). However, birds that are infected with ABV but that are clinically healthy have also been recognized (6). Infected birds can shed viral RNA intermittently (9), and not all infected birds seroconvert (5). For psittacine flock management, control of an AΒV infection is critical, e.g., by repeated testing of breeding stock and removal of ABV-positive birds (2,5). However, in breeding projects of rare species, every individual is genetically important and cannot be lost. Therefore, pairing infected, but clinically healthy, birds separately from birds that test negative for the virus might represent an option. For this possibility to be viable, whether vertical transmission of ABV can take place must be further clarified. A study investigating the distribution of ABV in tissues of PDD-positive birds has demonstrated ABV antigen in follicular cells, which may point toward vertical transmission (9).
    Emerging Infectious Diseases 12/2011; 17(12):2390-1. · 6.79 Impact Factor

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