Parrot Bornavirus Research Articles

Synergistic antiviral activity of ribavirin and interferon-α against parrot bornaviruses in avian cells.

Avian bornaviruses are the causative agents of proventricular dilatation disease (PDD), a widely distributed and often fatal disease in captive psittacines. Because neither specific prevention measures nor therapies against PDD and bornavirus infections are currently available, new antiviral strategies are required to improve animal health. We show here that the nucleoside analogue ribavirin inhibited bornavirus activity in a polymerase reconstitution assay and reduced viral load in avian cell lines infected with two different parrot bornaviruses. Furthermore, we observed that ribavirin enhanced type I IFN signalling in avian cells. Combined treatment of avian bornavirus-infected cells with ribavirin and recombinant IFN-α strongly enhanced the antiviral efficiency compared to either drug alone. The combined use of ribavirin and type I IFN might represent a promising new strategy for therapeutic treatment of captive parrots persistently infected with avian bornaviruses.

Parrot Bornavirus (PaBV)-2 isolate causes different disease patterns in cockatiels than PaBV-4

ABSTRACTPsittaciform 1 bornavirus (PaBV) has already been shown to be the aetiologic agent of proventricular dilatation disease, a significant disease of birds. However, the pathogenesis of PaBV infection has not yet been resolved and valid data regarding the pathogenicity of different PaBV species are lacking. Thus, the present study was aimed to characterize the influence of two different PaBV species on the course of disease. Eighteen cockatiels were inoculated intracerebrally (i.c.) or intravenously (i.v.) with a PaBV-2 isolate under the same conditions as in a previous study using PaBV-4. Birds were surveyed and sampled for 33 weeks to analyse the course of infection and disease in comparison to that of PaBV-4. Similar to PaBV-4, PaBV-2 induced a persistent infection with seroconversion (from day 6 p.i. onwards) and shedding of viral RNA (from day 27 p.i. onwards). However, in contrast to PaBV-4, more birds displayed clinical signs and disease progression was more severe. After PaBV-2 infection, 12 birds exhibited clinical signs and 10 birds revealed a dilated proventriculus in necropsy. After PaBV-4 infection only four birds revealed clinical signs and seven birds showed a dilatation of the proventriculus. Clinically, different courses of disease were observed after PaBV-2 infection, mainly affecting the gastrointestinal tract. This had not been detected after PaBV-4 infection where more neurological signs were noted. The results provide evidence for different disease patterns according to different PaBV species, allowing the comparison between the infection with two PaBV species, and thus underlining the role of viral and individual host factors for disease outcome.

The genome sequence of parrot bornavirus 5.

Although several new avian bornaviruses have recently been described, information on their evolution, virulence, and sequence are often limited. Here we report the complete genome sequence of parrot bornavirus 5 (PaBV-5) isolated from a case of proventricular dilatation disease in a Palm cockatoo (Probosciger aterrimus). The complete genome consists of 8842 nucleotides with distinct 5' and 3' end sequences. This virus shares nucleotide sequence identities of 69-74 % with other bornaviruses in the genomic regions excluding the 5' and 3' terminal sequences. Phylogenetic analysis based on the genomic regions demonstrated this new isolate is an isolated branch within the clade that includes the aquatic bird bornaviruses and the passerine bornaviruses. Based on phylogenetic analyses and its low nucleotide sequence identities with other bornavirus, we support the proposal that PaBV-5 be assigned to a new bornavirus species:- Psittaciform 2 bornavirus.

Parrot bornavirus-2 and -4 RNA detected in wild bird samples in Japan are phylogenetically adjacent to those found in pet birds in Japan.

Bornaviruses (family Bornaviridae) are non-segmented negative-strand RNA viruses. Avian bornaviruses (ABVs), which are causative agents of proventricular dilatation disease, are a genetically diverse group with at least 15 genotypes, including parrot bornaviruses (PaBVs) and aquatic bird bornavirus 1(ABBV-1). Borna disease virus 1(BoDV-1), which infects mammals and causes neurological diseases, has also been reported to infect avian species, although the numbers of the cases have been markedly fewer than those of ABVs. In this study, we conducted genetic surveillance to detect ABVs (PaBV-1 to -5 and ABBV-1) and BoDV-1 in wild birds in Japan. A total of 2078 fecal or cloacal swab samples were collected from wild birds in 2006, 2007, 2008, and 2011, in two regions of Japan. The results demonstrated the presence of PaBV-2 and -4 RNA, while no positive results for other PaBVs, ABBV-1, and BoDV-1 were obtained. PaBV-2 and -4 RNA were detected in 18 samples (0.9 %) of the genera Anas, Grus, Larus, Calidris, Haliaeetus, and Emberiza, in which either PaBV-2 RNA or PaBV-4 RNA, or both PaBV-2 and -4 RNA were detected in 15 (0.7 %), 5 (0.2 %), and 2 (0.1 %) samples, respectively. The nucleotide sequences of PaBV-2 and -4 detected in these samples from wild birds are phylogenetically close to those found in samples from pet birds in Japan, with identities ranging from 99.8 to 100 % and from 98.2 to 99.4 %, respectively. To the best of our knowledge, this is the first report on the detection of PaBV-2 and -4 RNA detected in samples from wild birds.

Coding-complete sequencing classifies parrot bornavirus 5 into a novel virus species.

In this study, we determined the sequence of the coding region of an avian bornavirus detected in a blue-and-yellow macaw (Ara ararauna) with pathological/histopathological changes characteristic of proventricular dilatation disease. The genomic organization of the macaw bornavirus is similar to that of other bornaviruses, and its nucleotide sequence is nearly identical to the available partial parrot bornavirus 5 (PaBV-5) sequences. Phylogenetic analysis showed that these strains formed a monophyletic group distinct from other mammalian and avian bornaviruses and in calculations performed with matrix protein coding sequences, the PaBV-5 and PaBV-6 genotypes formed a common cluster, suggesting that according to the recently accepted classification system for bornaviruses, these two genotypes may belong to a new species, provisionally named Psittaciform 2 bornavirus.

Ribavirin Inhibits Parrot Bornavirus 4 Replication in Cell Culture.

Parrot bornavirus 4 is an etiological agent of proventricular dilatation disease, a fatal neurologic and gastrointestinal disease of psittacines and other birds. We tested the ability of ribavirin, an antiviral nucleoside analog with antiviral activity against a range of RNA and DNA viruses, to inhibit parrot bornavirus 4 replication in duck embryonic fibroblast cells. Two analytical methods that evaluate different products of viral replication, indirect immunocytochemistry for viral specific nucleoprotein and qRT-PCR for viral specific phosphoprotein gene mRNA, were used. Ribavirin at concentrations between 2.5 and 25 μg/mL inhibited parrot bornavirus 4 replication, decreasing viral mRNA and viral protein load, in infected duck embryonic fibroblast cells. The addition of guanosine diminished the antiviral activity of ribavirin suggesting that one possible mechanism of action against parrot bornavirus 4 may likely be through inosine monophosphate dehydrogenase inhibition. This study demonstrates parrot bornavirus 4 susceptibility to ribavirin in cell culture.

Survey of bornaviruses in pet psittacines in Brazil reveals a novel parrot bornavirus

Avian bornaviruses are the causative agents of proventricular dilatation disease (PDD), a fatal neurological disease considered to be a major threat to psittacine bird populations. We performed a survey of the presence of avian bornaviruses and PDD in pet psittacines in Brazil and also studied PDD's clinical presentation as well as the genomic variability of the viruses. Samples from 112 psittacines with clinical signs compatible with PDD were collected and tested for the presence of bornaviruses. We found 32 birds (28.6%) positive for bornaviruses using reverse transcriptase polymerase chain reaction (RT-PCR). Twenty-one (65.6%) of the 32 bornavirus-positive birds presented neurological signs, seven (21.9%) presented undigested seeds in feces, four (12.5%) showed proventricular dilatation, six (18.8%) regurgitation, three (9.4%) feather plucking and three (9.4%) sudden death. The results confirm that avian bornaviruses are present in pet psittacines in Brazil, and sequence analysis identified a distinct virus, named parrot bornavirus 8 (PaBV-8).