Patricia L. Gray

Use of avian bornavirus isolates to induce proventricular dilatation disease in conures

The fulfillment of Koch’s postulates shows that the virus causes proventricular dilatation disease in parrots.

Molecular characterization of the cloacal microbiota of wild and captive parrots.

The gastrointestinal microbiota plays a fundamental role in health and disease. Only limited data are available about the composition of the intestinal microbiota of captive animals compared to those of wild animals. The aim of the present study was to characterize the cloacal microbiota of apparently healthy wild and captive parrots. A total of 16 parrots, 8 wild and 8 captive, belonging to 3 different species, were used in this study. Cloacal material was collected via cloacal swabbing. DNA was extracted and 16S rRNA genes were amplified using universal bacterial primers. Constructed 16S rRNA gene clone libraries were compared between groups. A total of 518 clones were analyzed, and 49 operational taxonomic units (OTUs) were identified. The OTUs were classified in 4 bacterial phyla: Firmicutes (72.9%), Proteobacteria (14.9%), Actinobacteria (12%), and Bacteroidetes (0.2%). Bacterial diversity was significantly lower in wild birds than in captive birds. Principal component analysis based on the Unifrac distance metric indicated that the cloacal microbiota differed between wild and captive parrots. Staphylococcus saprophyticus was significantly more abundant in wild birds, while Escherichia coli was significantly more abundant in captive birds. In conclusion, wild and captive parrots appear to have differences in the composition of their cloacal bacterial microbiota. The clinical significance of these differences remains to be determined.

Unusual and severe lesions of proventricular dilatation disease in cockatiels (Nymphicus hollandicus) acting as healthy carriers of avian bornavirus (ABV) and subsequently infected with a virulent strain of ABV

A flock of 14 apparently healthy cockatiels, purchased from a single aviary, was tested for the presence of avian bornavirus (ABV). Twelve birds were found to be intermittently shedding ABV, predominantly genotype 4. Four of the cockatiels known to be shedding ABV4 were subsequently challenged with the tissue culture derived, virulent M24 strain of ABV4. The challenged birds remained in apparent good health until day 92 when one was found dead. The remaining three birds began to exhibit severe neurologic signs, ataxia and convulsions on day 110 and were euthanized. On necropsy, all four birds showed mild proventricular enlargement. In contrast, histopathological examination showed unusually severe and widespread tissue lesions. These included massive lymphocytic infiltration and lymphoid nodule formation within and around the ganglia throughout the gastrointestinal tract. There were similar lesions in the medullary cords of the adrenal gland, heart, spleen, liver, kidney, lungs, pancreas, testes and ovary. Immunohistochemistry demonstrated ABV P antigen not only in the cells of the central and autonomic nervous systems, but also within the mononuclear cells infiltrating the various organs. Two healthy cockatiels, one of which was a known ABV carrier, were inoculated with uninfected tissue culture cells and euthanized on day 150. These birds showed no gross lesions of proventricular dilatation disease but had a mild lymphocytic infiltration in their liver, spleen, and kidneys. Prior infection with ABV did not therefore confer significant immunity on these birds, and may have resulted in increased disease severity following challenge.

The Isolation, Pathogenesis, Diagnosis, Transmission, and Control of Avian Bornavirus and Proventricular Dilatation Disease

Proventricular dilatation disease (PDD) is a common infectious neurologic disease of birds comprising a dilatation of the proventriculus by ingested food as a result of defects in intestinal motility, which affects more than 50 species of psittacines, and is also known as Macaw wasting disease, neuropathic ganglioneuritis, or lymphoplasmacytic ganglioneuritis. Definitive diagnosis of PDD has been problematic due to the inconsistent distribution of lesions. Since its discovery, avian bornavirus (ABV) has been successfully cultured from the brains of psittacines diagnosed with PDD, providing a source of antigen for serologic assays and nucleic acid for molecular assays. This article provides evidence that ABV is the etiologic agent of PDD. Recent findings on the transmission, epidemiology, pathogenesis, diagnosis, and control of ABV infection and PDD are also reviewed.

Histopathology and the detection of avian bornavirus in the nervous system of birds diagnosed with proventricular dilatation disease.

Avian bornavirus (ABV) is currently considered a probable etiologic agent of proventricular dilatation disease (PDD) of psittacines. We tested 24 stored avian brain samples, processed for histopathology and retained following their submission for necropsy or histopathology to the Schubot Exotic Bird Center diagnostic laboratory in 1992. Thirteen of these samples were from birds diagnosed at that time as suffering from PDD. The remaining 11 samples were diagnosed as suffering from diseases other than PDD. Immunohistochemistry was performed using an antiserum directed against the ABV nucleoprotein (N-protein). Stained slides were read by an investigator unaware of their prior histopathology results. Cells containing ABV N-protein were present in the nervous tissues of all 13 PDD cases. One bird not previously diagnosed with PDD also had ABV N-protein in its brain. A review of this birds necropsy report indicated that it was, most probably, also suffering from PDD. The remaining 10 non-PDD birds had no detectable N-protein in their brains. The N-protein was present in the cerebrum, cerebellum and spinal cord. These findings support other studies that indicate that ABV is an etiological agent of PDD.

Proventricular Dilatation Disease in Cockatiels (Nymphicus hollandicus) After Infection With a Genotype 2 Avian Bornavirus

Abstract An isolate of genotype 2 avian bornavirus (ABV) was recovered from a cockatiel (Nymphicus hollandicus) that was euthanatized for an unrelated lesion and showing no clinical evidence of proventricular dilatation disease (PDD). On histopathologic examination, mild inflammatory lesions were present in the heart and brain, but gastrointestinal lesions characteristic of classic PDD were not observed. To investigate if this ABV2 isolate had reduced virulence, the virus was propagated in duck embryo fibroblasts and inoculated into 2 adult cockatiels by the oral and intramuscular routes. One bird developed clinical signs on day 33 and was euthanatized on day 36. The second challenged bird developed clinical signs on day 41 and was euthanatized on day 45. At necropsy, the proventriculus of both birds was slightly enlarged. Histopathologic examination showed lesions typical of PDD in the brain, spinal cord, heart, adrenal gland, and intestine. A control, uninoculated cockatiel was apparently healthy when euthanatized on day 50. These results show that ABV2 is now the second ABV genotype to be formally shown to cause PDD.

Humoral response to Mycobacterium avium subsp. avium in naturally infected ring-neck doves (Streptopelia risoria)

Creation of a reliable and easy to use serologic test would greatly improve ante mortem diagnosis of Mycobacterium avium subsp. avium and aid in the control of avian mycobacteriosis, particularly in captive birds. In order to determine whether serodiagnostics could be of value in testing ring-neck doves (Streptopelia risoria) for M. a. avium infection, Western blot analysis was used to assess the humoral response of ring-neck doves exposed to M. a. avium, and to evaluate whether an association could be made between the humoral response and necropsy findings, histopathology, culture, and PCR testing. Western blot results were examined for reactivity patterns associating humoral response with infection status, severity and type of lesions (diffuse vs. multifocal granulomatous inflammation) and phenotype (white vs. non-white). A sensitivity of 88.24% and a specificity of 100% were achieved utilizing Western blot analysis to detect M. a. avium infection in ring-neck doves, offering a negative predictive value of 93% and a positive predictive value of 100%. While Western blot analysis results did not reflect lesion severity, lesion type did partially correspond with the humoral response. The findings of the present study indicate that serologic testing can be used as a valuable ante mortem screening tool for identifying ring-neck doves infected with M. a. avium.

Detection of an antigen specific for proventricular dilation disease in psitticine birds

PROVENTRICULAR dilation disease (pdd) affects many species of birds, especially large psittacines such as macaws ([Gregory 1994][1]). The classical presenting sign is paralysis and dilation of the proventriculus secondary to nerve damage. pdd is believed to be caused by a virus. [Grund and others (

Complete Genome Sequence of Avian Bornavirus Genotype 1 from a Macaw with Proventricular Dilatation Disease

ABSTRACT Avian bornaviruses (ABV) were first detected and described in 2008. They are the etiologic agents of proventricular dilatation disease (PDD), a frequently fatal neurologic disease of captive parrots. Seven ABV genogroups have been identified worldwide from a variety of sources, and that number may increase as surveillance for novel bornaviruses continues. Here, we report the first complete sequence of a genogroup 1 avian bornavirus (ABV1).

Evaluation of Multidrug Therapy With Azithromycin, Rifampin, and Ethambutol for the Treatment of Mycobacterium avium subsp avium in Ring-neck Doves (Streptopelia risoria): An Uncontrolled Clinical Study

Abstract An uncontrolled clinical study was conducted to evaluate the efficacy of a multidrug protocol in 16 ring-neck doves (Streptopelia risoria) from a flock naturally infected with Mycobacterium avium subsp avium. The doves were considered infected on the basis of a high prevalence of infection in a group of 29 birds that were euthanatized from the same flock and clinical signs and pathologic results consistent with infection in the remaining birds. All birds were treated with azithromycin (43 mg/kg), rifampin (45 mg/kg), and ethambutol (30 mg/kg) administered orally once daily for 180 days. Five birds died during treatment and were confirmed positive for mycobacteriosis on postmortem examination. Of the remaining 11 birds, infection and disease were present in 9 (81.8%) at the end of the treatment. Postmortem investigation showed that 2 mycobacterial isolates were resistant to ethambutol, intermediately sensitive to rifampin, and sensitive to azithromycin. Microscopic examination of liver sections equivalent of those that would be taken for biopsy showed that biopsy as a method of monitoring birds for treatment success had poor sensitivity. Toxicity associated with drug therapy was not observed in these doves nor in 6 outwardly healthy ring-neck doves exposed to the same treatment. The results of this study showed that this protocol of azithromycin, rifampin, and ethambutol has poor efficacy when administered for 180 days for treatment of doves infected with M avium subsp avium.