Avian Bornavirus is Present in Many Tissues of Psittacine Birds with Histopathologic Evidence of Proventricular Dilatation Disease

Abstract

Abstract. Proventricular dilatation disease (PDD) is a neurologic disease of psittacine birds suspected to be caused by a recently identified Avian bornavirus (ABV). In the current report, data supporting the causal association of ABV with PDD are presented. Immunohistochemistry (IHC) with rabbit polyclonal antiserum raised against ABV nucleocapsid protein was used to identify cell and organ distribution of viral antigen. The ABV antigen was most consistently detected in brain, spinal cord, adrenal gland, pancreas, and kidney. Histopathologic evaluation was correlated with ABV-specific polymerase chain reaction (PCR) and immunohistochemical tests in multiple tissues from 16 psittacine birds with and without PDD. Using histopathologic diagnosis as the gold standard, the sensitivity and specificity of IHC for ABV antigens were found to be 100% and 100%, respectively. Many more tissues were positive for ABV RNA by reverse transcription PCR than were positive for pathologic changes or viral antigens by IHC, indicating the presence of subclinical or asymptomatic infection at many sites.

Avian bornavirus in the urine of infected birds

“…2 Most sources consider the most likely method of viral transmission as fecal/oral, with virus assumed to be excreted in the feces. 1,5 However, we postulate that in fact ABV may be more likely to be spread via a urinary route. Multiple researchers have described the presence of ABV within the kidney, in Dovepress submit your manuscript | www.dovepress.com PDD-affected and ABV-infected birds via PCR and immunohistochemical staining.…”

“…Multiple researchers have described the presence of ABV within the kidney, in Dovepress submit your manuscript | www.dovepress.com PDD-affected and ABV-infected birds via PCR and immunohistochemical staining. 4,5,9 Indeed, some have postulated that ABV may be transmitted via the kidney or urine. 5 Avian droppings consist of a mixture of feces and urine.…”

“…4,5,9 Indeed, some have postulated that ABV may be transmitted via the kidney or urine. 5 Avian droppings consist of a mixture of feces and urine. Both are delivered to the cloaca from the ureter and intestine and then excreted as a mixture.…”

“…In fact, it commonly spreads to all the major organs, including heart, liver, adrenals, and the kidneys. 1,[3][4][5] Birds infected with ABV have an incubation period that may range from 20 days to several years. 6 For much of this time, the birds may appear healthy but shed the virus through their choana, nares, and droppings.…”

Proventricular Dilatation Disease Associated with Avian Bornavirus Infection in a Citron-Crested Cockatoo that Was Born and Hand-Reared in Japan

“…In general, tissues in which viral RNA is detected by RT-PCR show histopathologic lesions attributable to PDD. However, a recent report also documented the same result in the cerebrum [12], and the reason for these results is unknown. Little is known about the mode of transmission of ABV, including this reported case, but previous studies have suggested horizontal transmission of the virus via oral and/or respiratory routes [13].…”