Avian Bornavirus Research Articles

Bornaviruses in naturally infected Psittacus erithacus in Portugal: insights of molecular epidemiology and ecology

ABSTRACTBackground: The genus Orthobornavirus comprises non-segmented, negative-stranded RNA viruses able to infect humans, mammals, reptiles and various birds. Parrot bornavirus 1 to 8 (PaBV-1 to 8) causes neurological and/or gastrointestinal syndromes and death on psittacines. We aimed to identify and to produce epidemiologic knowledge about the etiologic agent associated with a death of two female Psittacus erithacus (grey parrot).Methods and Results: Both parrots were submitted for a complete standardised necropsy. Tissue samples were analysed by PCR. The findings in necropsy were compatible with bornavirus infection. Analysis revealed PaBV-4 related with genotypes detected in captive and in wild birds. The N and X proteins of PaBV-4 were more related to avian bornaviruses, while phosphoprotein was more related to variegated squirrel bornavirus 1 (VSBV-1). Within the P gene/phosphoprotein a highly conserved region between and within bornavirus species was found.Conclusions: Portugal is on the routes of the intensive world trade of psittacines. Broad screening studies are required to help understanding the role of wild birds in the emergence and spread of pathogenic bornaviruses. PaBV-4 phosphoprotein is closer to VSBV-1 associated with lethal encephalitis in humans than with some of the avian bornaviruses. The highly conserved P gene/phosphoprotein region is a good target for molecular diagnostics screenings.

Detection and phylogenetic analysis of parrot bornavirus 4 identified from a Swedish Blue-winged macaw (Primolius maracana) with unusual nonsuppurative myositis

ABSTRACTBackground: The genus Orthobornavirus comprises RNA viruses infecting humans, mammals, birds and reptiles, where parrot bornavirus 1 to 8 causes fatal neurological and/or gastrointestinal syndromes in psittacines. There is, to the best of our knowledge, no publication describing avian bornaviruses in pet parrots in Sweden. We aimed to identify and to produce epidemiologic knowledge about the etiologic agent associated with a history of severe weight loss and death of a Primolius maracana.Methods and results: The results of histopathology, immunohistochemistry and real-time RT-PCR were compatible with avian bornavirus infection. Sequencing indicated infection by parrot bornavirus 4 (PaBV-4). The genotype reported shared high identity with PaBV-4 identified from pet psittacines and from wild birds in several countries. The N gene and X protein showed genotype clusters formation. P protein revealed to be more conserved within and between species of bornaviruses. Findings suggest horizontal transmission within and between avian orders and species.Conclusion: There seems to be a worldwide trading without biosafety measures, hence, further disease transmission could be avoided. For screening purposes, the P gene is a good candidate as a universal target in molecular diagnostics. Wild birds may be key pieces in the puzzle of bornavirus epidemiology.

Retrospective Evaluation of Clinical Signs and Gross Pathologic Findings in Birds Infected With Mycobacterium genavense.

Mycobacterium genavense is regarded as the primary cause of mycobacteriosis in passerine and psittacine birds kept in captivity. Mycobacterium genavense is a potential zoonotic pathogen; therefore, early antemortem detection in birds is needed. In humans, infections with M genavense are found predominantly in immunocompromised people. To investigate clinical signs and pathologic lesions and to determine the prevalence of coinfections in birds infected with M genavense, we reviewed records of 83 birds in which DNA from M genavense had been detected via real-time polymerase chain reaction. To evaluate clinical signs in birds presented as patients, results of standardized examinations of 60 birds and radiographic results from 37 birds were investigated. Necropsy results of 82 of the 83 birds were evaluated, including results of additional parasitologic, bacteriologic, and virologic examinations. Birds included in the study comprised 15 species in the orders Passeriformes, Psittaciformes, Coliiformes, Columbiformes, Coraciiformes, and Ciconiiformes. A wide range of clinical manifestations were documented, including neurologic disorders, ocular manifestations, and gastrointestinal signs. Of the 60 birds examined clinically, 15% showed no clinical signs. Coinfections with a wide range of pathogens were detected in 52% (43 of 83) of the tested birds. Coinfections included Macrorhabdus ornithogaster, circovirus, polyomavirus, avian bornavirus, adenovirus, Mycobacterium avium ssp. avium/ silvaticum, Mycoplasma species, Salmonella species, Escherichia coli, Aspergillus species, and various parasites. The high number of coinfections may reflect an impaired immune status in the birds examined. These results also suggest a broad host range for M genavense, and the existence of various clinical signs that may be strongly associated with coinfections with other pathogens.

Aquatic bird bornavirus 1 infection in a captive Emu (Dromaius novaehollandiae): presumed natural transmission from free-ranging wild waterfowl

ABSTRACTAn adult female emu (Dromaius novaehollandiae) presented with anorexia, maldigestion, weight loss, and various subtle nervous deficits. After four months of unrewarding diagnostics, treatments, and supportive care, the emu was euthanized due to lack of clinical improvement and progressive weight loss. Gross pathology revealed a very narrow pylorus and multiple flaccid diverticula of the small intestines. Histopathological findings included severe lymphoplasmacytic encephalomyelitis and multifocal lymphocytic neuritis associated with the gastrointestinal tract. Immunohistochemistry and polymerase chain reaction on the brain were positive for an avian bornavirus (ABV), and partial sequencing of the matrix gene identified aquatic bird bornavirus-1 (ABBV-1), 100% identical to viruses circulating in wild Canada geese (Branta canadensis). As wild geese frequently grazed and defaecated in the emu’s outdoor exhibit, natural transmission of ABBV-1 from free-ranging waterfowl to the emu was presumed to have occurred.

Antiviral activity of favipiravir (T-705) against mammalian and avian bornaviruses

Bornaviruses, non-segmented, negative-strand RNA viruses, are emerging agents with the potential for causing various types of neurological symptoms. Previous studies have shown that ribavirin, a nucleic acid analog with broad-spectrum antiviral activity, has a potent antiviral effect on infections with a mammalian bornavirus, Borna disease virus (BoDV-1), as well as avian bornaviruses. However, ribavirin-based treatment does not eliminate bornaviruses from persistently infected cells and viral replication resumes after treatment cessation. Therefore, the development of a novel effective anti-bornavirus treatment is needed. To identify such agents, we screened nucleoside/nucleotide mimetics for agents with anti-bornavirus activity. We used Vero cells infected with recombinant BoDV-1 carrying Gaussia luciferase to monitor BoDV-1 replication and found that favipiravir (T-705) is a potent inhibitor of BoDV-1 replication. T-705 suppressed BoDV-1 replication in a dose- and time-dependent manner during the observation period of 4 weeks. Notably, no increase in luciferase activity or in the number of BoDV-1-positive cells was detected in the at least 4 weeks following T-705 removal. Finally, we demonstrated that T-705 effectively suppressed viral replication of both BoDV-1 and an avian bornavirus, suggesting that T-705 may have a strong antiviral activity against a broad range of bornaviruses. Our findings provide a novel and effective option for treating persistent bornavirus infection.

Viral vector vaccines protect cockatiels from inflammatory lesions after heterologous parrot bornavirus 2 challenge infection

Avian bornaviruses are causative agents of proventricular dilatation disease (PDD), a chronic neurologic and often fatal disorder of psittacines including endangered species. To date no causative therapy or immunoprophylaxis is available. Our previous work has shown that viral vector vaccines can delay the course of homologous bornavirus challenge infections but failed to protect against PDD when persistent infection was not prevented.The goal of this study was to refine our avian bornavirus vaccination and infection model to better represent natural bornavirus infections in order to achieve full protection against a heterologous challenge infection.We observed that parrot bornavirus 2 (PaBV-2) readily infected cockatiels (Nymphicus hollandicus) by combined intramuscular and subcutaneous injection with as little as 102.7foci-forming units (ffu) per bird, whereas a 500-fold higher dose of the same virus administered via peroral and oculonasal route did not result in persistent infection. These results indicated that experimental bornavirus challenge infections with this virus should be performed via the parenteral route.Prime-boost vaccination of cockatiels with Newcastle disease virus (NDV) and modified vaccinia virus Ankara (MVA) vectors expressing the nucleoprotein and phosphoprotein genes of PaBV-4 substantially blocked bornavirus replication following parenteral challenge infection with 103.5ffu of heterologous PaBV-2. Only two out of six vaccinated birds had very low viral levels detectable in a few organs. As a consequence, only one vaccinated bird developed mild PDD-associated microscopic lesions, while mock-vaccinated controls were not protected against PaBV-2 infection and inflammation.Our results demonstrate that NDV and MVA vector vaccines can protect against invasive heterologous bornavirus challenge infections and subsequent PDD. These vector vaccines represent a promising tool to combat avian bornaviruses in psittacine populations.

Viral vector vaccines expressing nucleoprotein and phosphoprotein genes of avian bornaviruses ameliorate homologous challenge infections in cockatiels and common canaries.

Avian bornaviruses are causative agents of proventricular dilatation disease (PDD), an often fatal disease of parrots and related species (order Psittaciformes) which is widely distributed in captive psittacine populations and may affect endangered species. Here, we established a vaccination strategy employing two different well described viral vectors, namely recombinant Newcastle disease virus (NDV) and modified vaccinia virus Ankara (MVA) that were engineered to express the phosphoprotein and nucleoprotein genes of two avian bornaviruses, parrot bornavirus 4 (PaBV-4) and canary bornavirus 2 (CnBV-2). When combined in a heterologous prime/boost vaccination regime, NDV and MVA vaccine viruses established self-limiting infections and induced a bornavirus-specific humoral immune response in cockatiels (Nymphicus hollandicus) and common canaries (Serinus canaria forma domestica). After challenge infection with a homologous bornavirus, shedding of bornavirus RNA and viral loads in tissue samples were significantly reduced in immunized birds, indicating that vaccination markedly delayed the course of infection. However, cockatiels still developed signs of PDD if the vaccine failed to prevent viral persistence. Our work demonstrates that avian bornavirus infections can be repressed by vaccine-induced immunity. It represents a first crucial step towards a protective vaccination strategy to combat PDD in psittacine birds.

Phylogenetic Analysis Supports Horizontal Transmission as a Driving Force of the Spread of Avian Bornaviruses.

BackgroundAvian bornaviruses are a genetically diverse group of viruses initially discovered in 2008. They are known to infect several avian orders. Bornaviruses of parrots and related species (Psittaciformes) are causative agents of proventricular dilatation disease, a chronic and often fatal neurologic disease widely distributed in captive psittacine populations. Although knowledge has considerably increased in the past years, many aspects of the biology of avian bornaviruses are still undiscovered. In particular, the precise way of transmission remains unknown.Aims and MethodsIn order to collect further information on the epidemiology of bornavirus infections in birds we collected samples from captive and free-ranging aquatic birds (n = 738) and Passeriformes (n = 145) in Germany and tested them for the presence of bornaviruses by PCR assays covering a broad range of known bornaviruses. We detected aquatic bird bornavirus 1 (ABBV-1) in three out of 73 sampled free-ranging mute swans (Cygnus olor) and one out of 282 free-ranging Eurasian oystercatchers (Haematopus ostralegus). Canary bornavirus 1 (CnBV-1), CnBV-2 and CnBV-3 were detected in four, six and one out of 48 captive common canaries (Serinus canaria forma domestica), respectively. In addition, samples originating from 49 bornavirus-positive captive Psittaciformes were used for determination of parrot bornavirus 2 (PaBV-2) and PaBV-4 sequences. Bornavirus sequences compiled during this study were used for phylogenetic analysis together with all related sequences available in GenBank.Results of the StudyWithin ABBV-1, PaBV-2 and PaBV-4, identical or genetically closely related bornavirus sequences were found in parallel in various different avian species, suggesting that inter-species transmission is frequent relative to the overall transmission of these viruses. Our results argue for an important role of horizontal transmission, but do not exclude the additional possibility of vertical transmission. Furthermore we defined clearly separated sequence clusters within several avian bornaviruses, providing a basis for an improved interpretation of transmission events within and between wild bird populations and captive bird collections.

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.

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.

Isolation of avian bornaviruses from psittacine birds using QT6 quail cells in Japan.

Avian bornaviruses (ABVs) were recently discovered as the causative agents of proventricular dilatation disease (PDD). Although molecular epidemiological studies revealed that ABVs exist in Japan, no Japanese isolate has been reported thus far. In this study, we isolated four strains of Psittaciform 1 bornavirus from psittacine birds affected by PDD using QT6 quail cells. To our knowledge, this is the first report to isolate ABVs in Japan and to show that QT6 cells are available for ABV isolation. These isolates and QT6 cells would be powerful tools for elucidating the fundamental biology and pathogenicity of ABVs.

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.

Identification of avian bornavirus in a Himalayan monal (Lophophorus impejanus) with neurological disease

A one-year-old male Himalayan monal (Lophophorus impejanus) was presented for veterinary attention with a history of chronic wasting, weakness and ataxia. The bird died, and post-mortem findings included mild non-suppurative encephalitis and degenerative encephalopathy, lymphoplasmacytic myenteric ganglioneuritis (particularly of the proventriculus), and Wallerian degeneration of the sciatic nerves. Avian bornavirus (ABV) was identified in the brain by immunohistochemistry and reverse-transcriptase polymerase chain reaction. Sequencing of the reverse-transcriptase polymerase chain reaction product indicated the presence of ABV genotype 4, which is generally associated with disease in psittacine birds. Subsequent to the death of the pheasant, ABV genotype 4 was identified at autopsy from a juvenile white-bellied caique (Pionites leucogaster) in the same collection. We hypothesize that the pheasant became infected through contact with psittacine birds with which it shared an aviary. We believe this to be the first reported case of natural ABV infection in a bird in the Order Galliformes.

Avian Bornaviruses in North American Gulls

Avian bornaviruses, recently described members of the family Bornaviridae, have been isolated from captive parrots and passerines as well as wild waterfowl in which they may cause lethal neurologic disease. We report detection of avian bornavirus RNA in the brains of apparently healthy gulls. We tested 439 gull brain samples from 18 states, primarily in the northeastern US, using a reverse-transcriptase PCR assay with primers designed to detect a conserved region of the bornavirus M gene. Nine birds yielded a PCR product of appropriate size. Sequencing of PCR products indicated that the virus was closely related to aquatic bird bornavirus 1 (ABBV-1). Viral RNA was detected in Herring Gulls (Larus argentatus), Ring-billed Gulls (Larus delawarensis), and Laughing Gulls (Leucophaeus atricilla). Eight of the nine positive birds came from the New York/New Jersey area. One positive Herring Gull came from New Hampshire. Histopathologic examination of one well-preserved brain from a Herring Gull from Union County New Jersey, showed a lymphocytic encephalitis similar to that observed in bornavirus-infected parrots and geese. Bornavirus N protein was confirmed in two Herring Gull brains by immunohistochemistry. Thus ABBV-1 can infect gulls and cause encephalitic brain lesions similar to those observed in other birds.

Taxonomic reorganization of the family Bornaviridae.

Knowledge of bornaviruses has expanded considerably during the last decade. A possible reservoir of mammalian Borna disease virus has been identified, divergent bornaviruses have been detected in birds and reptiles, and endogenous bornavirus-like elements have been discovered in the genomes of vertebrates of several species. Previous sequence comparisons and alignments have indicated that the members of the current family Bornaviridae are phylogenetically diverse and are not adequately classified in the existing bornavirus taxonomy supported by the International Committee on Taxonomy of Viruses (ICTV). We provide an update of these analyses and describe their implications for taxonomy. We propose retaining the family name Bornaviridae and the genus Bornavirus but reorganizing species classification. PAirwise Sequence Comparison (PASC) of bornavirus genomes and Basic Local Alignment Search Tool (BLAST) comparison of genomic and protein sequences, in combination with other already published phylogenetic analyses and known biological characteristics of bornaviruses, indicate that this genus should include at least five species: Mammalian 1 bornavirus (classical Borna disease virus and divergent Borna disease virus isolate No/98), Psittaciform 1 bornavirus (avian/psittacine bornaviruses 1, 2, 3, 4, 7), Passeriform 1 bornavirus (avian/canary bornaviruses C1, C2, C3, LS), Passeriform 2 bornavirus (estrildid finch bornavirus EF), and Waterbird 1 bornavirus (avian bornavirus 062CG). This classification is also in line with biological characteristics of these viruses and their vertebrate hosts. A snake bornavirus, proposed to be named Loveridge's garter snake virus 1, should be classified as a member of an additional species (Elapid 1 bornavirus), unassigned to a genus, in the family Bornaviridae. Avian bornaviruses 5, 6, MALL, and another "reptile bornavirus" ("Gaboon viper virus") should stay unclassified until further information becomes available. Finally, we propose new virus names and abbreviations when necessary to achieve clear differentiation and unique identification.

Avian bornavirus in free-ranging psittacine birds, Brazil.

Avian bornavirus (ABV) has been identified as the cause of proventricular dilatation disease in birds, but the virus is also found in healthy birds. Most studies of ABV have focused on captive birds. We investigated 86 free-ranging psittacine birds in Brazil and found evidence for natural, long-term ABV infection.

Characterization of a new genotype of avian bornavirus from wild ducks.

BackgroundAvian bornaviruses (ABV) are a recently described group of intranuclear negative-stranded RNA viruses (Order Mononegavirales, Family Bornaviridae). At least 13 different ABV genotypes have been described. One genotype, the Canada goose genotype (ABV-CG), has been isolated from geese and swans and is widely distributed across North America.ResultsWe have isolated and characterized a previously undescribed genotype of avian bornavirus from the brains of wild ducks. This new genotype, provisionally designated ABV genotype MALL, was detected in 12 of 83 mallards, and 1 of 8 wood ducks collected at a single location in central Oklahoma. The virus was cultured on primary duck embryo fibroblasts, fragments were cloned, and its genome sequence of 8904 nucleotides determined. This new genotype has 72% nucleotide identity and 83% amino acid identity with the ABV-CG genotype previously shown to be present in geese and swans. Histologic and immunohistochemical examination of the brains and eyes of four positive ducks indicated the presence of virus-infected neurons and glia in their cerebrums and retinas in the absence of inflammation.ConclusionsMore than one genotype of ABV is circulating in North American waterfowl. While the infected ducks were not observed to be suffering from overt disease, based on the immunohistochemistry, we speculate that they may have suffered some visual impairment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-014-0197-9) contains supplementary material, which is available to authorized users.

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).

국내 청금강 앵무새(Ara ararauna )에서 psittacine beak and feather disease virus 최초 검출

Abstract A eight-month-old blue and yellow macaw ( Ara ararauna ) with psittacine beak and feather disease (PBFD)-suspected signs, such as, abnormal feather, depression and diarrhea, was presented to Animal Disease Intervention Center, Kyungpook National University in 16 April 2014. The partial ORF V1 gene of PBFD virus (PBFDV) was detected by polymerase chain reaction (PCR) from DNA templates extracted from feather, blood and cloacal swab sample of the bird, but no other viral DNAs that often infected in psittacine birds including avian bornavirus and avian polyomavirus were detected from the samples of the bird, indicating this case is due to single infection of PBFDV. Nucleotide sequence anal-ysis of the amplified partial ORF V1 gene was confirmed to have 96.7% and 93.6% homology with that of previously reported PBFDV strain (Genbank no. HM748924 and FJ685980). This report de-scribes the first detection of PBFDV in PBFD-suspected blue and yellow macaw in Korea. Key words : Psittacine beak and feather disease (PBFD), Blue and yellow macaw, Polymerase chain reaction (PCR)