Beak And Feather Disease Virus Isolates Research Articles

Evidence of circulation of beak and feather disease virus in captive psittacine and non-psittacine birds in Bangladesh.

Beak and feather disease virus (BFDV) is an emerging pathogen in many parts of the world that is responsible for causing beak and feather disease in birds. Since the virus is highly persistent in the environment and spreads by contact, birds raised in captivity are at a high risk of infection. Breeding, trading, and rearing of captive birds are becoming increasingly popular in many countries, including Bangladesh, increasing the risk of BFDV infection. However, it is unknown whether BFDV is circulating in captive birds in Bangladesh. This study was designed to conduct the first pilot survey to test the hypothesis that BFDV is circulating in Bangladesh. Feather samples were collected from 100 birds of 10 psittacine and two non-psittacine species from a breeding flock, three live-bird markets (LBMs), and two household flocks. Polymerase chain reaction (PCR) was used to detect the rep gene, together with sequencing and phylogenetic analysis. This study confirmed that BFDV is circulating in Bangladesh, with a positivity rate of 37%. The majority (78.38%) of PCR-positive birds were asymptomatic. The detection rate was higher in birds from the breeding flock (54.05%) than in LBMs (37.84%) and household flocks (8.11%) (P = 0.01). No significant variation was observed when considering the species (P = 0.14) and sex (P = 0.75) of the birds. Phylogenetic analysis suggested that the BFDV isolates found in LBMs and household flocks are genetically related to isolates from breeding flocks in the area as well as to many other isolates from different regions of the world. Further research needs to be done to determine the impact of this virus in the wider population.

Prevalence of Aves Polyomavirus 1 and Beak and Feather Disease Virus From Exotic Captive Psittacine Birds in Chile.

Avian polyomavirus disease and psittacine beak and feather disease (PBFD) are both contagious viral diseases in psittacine birds with similar clinical manifestations and characterized by abnormal feathers. To determine the prevalence of Aves polyomavirus 1 (APyV) and beak and feather disease virus (BFDV) in captive, exotic psittacine birds in Chile, feathers from 250 psittacine birds, representing 17 genera, were collected and stored during the period 2013-2016. Polymerase chain reaction testing was used to detect APyV and BFDV were detected in feather bulb samples. The results indicated that 1.6% (4/250) of the samples were positive for APyV, 23.2% (58/250) were positive to BFDV, and 0.8% (2/250) were positive to both APyV and BFDV. This is the first report, to our knowledge, of APyV and BFDV prevalence in captive, exotic psittacine birds in South America. Analysis of 2 Chilean partial sequences of the gene encoding agnoprotein 1a (APyV) and the replication-associated protein (BFDV) extends the knowledge of genomic variability for both APyV and BFDV isolates and their spectrum of hosts. No geographical marker was detected for the local isolates.

Beak and feather disease viruses circulating in Cape parrots (Poicepahlus robustus) in South Africa.

Captive and wild psittacines are vulnerable to the highly contagious psittacine beak and feather disease. The causative agent, beak and feather disease virus (BFDV), was recently detected in the largest remaining population of endangered Cape parrots (Poicepahlus robustus), which are endemic to South Africa. Full-length genomes were isolated and sequenced from 26 blood samples collected from wild and captive Cape parrots to determine possible origins of infection. All sequences had characteristic BFDV sequence motifs and were similar in length to those described in the literature. However, BFDV coat protein (CP) sequences from this study did not contain a previously identified bipartite nuclear localisation signal (NLS) within residues 39-56, which indicates that an alternate NLS is involved in shuttling the CP into the nucleus. Sequences from the wild population shared a high degree of similarity, irrespective of year or location, suggesting that the disease outbreak occurred close to the time when the samples were collected. Phylogenetic analysis of full-length genomes showed that the captive Cape parrot sequences cluster with those isolated from captive-bred budgerigars in KwaZulu-Natal Province, South Africa. Exposure to captive-bred Cape parrots from a breeding facility in KwaZulu-Natal is suggested as a possible source for the virus infection. Phylogenetic analysis of BFDV isolates from wild and captive Cape parrots indicated two separate infection events in different populations, which highlights the potential risk of introducing new strains of the virus into the wild population. The present study represents the first systematic investigation of BFDV virus diversity in the southern-most population of Cape parrots.

Rapid genotyping of beak and feather disease virus using high-resolution DNA melt curve analysis

Beak and feather disease virus (BFDV) is a significant pathogen both for wild and captive psittacine birds globally. Genotypic differentiation of BFDV isolates is crucial to establish effective control strategies for the conservation of endangered species and epidemiological investigations of disease outbreaks. The technique developed in this study is a simple, rapid and inexpensive genotyping method for BFDV using PCR and subsequent high-resolution melt (HRM) curve analysis. This was achieved using PCR amplification of the conserved Rep gene in the presence of a fluorescent DNA intercalating dye (SYTO9). HRM curve analysis of the resultant amplicon could readily differentiate between reference strain (92-SR14) and 18 other BFDV isolates used in this study. Analysis of the nucleotide sequences of the amplicon from each isolate revealed that each melt curve profile was related to a unique DNA sequence. The potential of the PCR–HRM curve analysis to differentiate inter-host genetic variation among critically endangered orange-bellied parrots, lorikeets and cockatoos was also evaluated. Phylogenetic tree topology based on partial Rep gene sequences used in this study showed that BFDV Rep gene sequence patterns were correlated with the results of HRM curve analysis. The results presented in this study indicate that this technique could be used in both clinical research and differentiation of BFDV isolates in a fraction of time without further nucleotide sequencing and provides a novel approach for the genetic screening of BFDV in clinical virology laboratories.

Molecular characterisation of beak and feather disease virus (BFDV) in New Zealand and its implications for managing an infectious disease

Beak and feather disease virus (BFDV) infections are often fatal to both captive and wild parrot populations. Its recent discovery in a wild population of native red-fronted parakeets has raised concerns for the conservation of native parrots, all of which are threatened or endangered. The question of a recent introduction versus a native genotype of the virus poses different conservation-management challenges, and thus, a clear understanding of the molecular phylogeny of BDFV is a crucial step towards integrated management planning. This study represents the first comprehensive attempt to screen New Zealand's endangered and threatened psittacines systematically for BFDV. We sampled and screened kakapos (Strigops habroptilus), kakas (Nestor meridionalis), keas (N. notabilis), Chatham parakeets (Cyanoramphus forbesi), Malherbe's parakeets (Cyanoramphus malherbi), yellow-crowned parakeets (C. auriceps) and red-fronted parakeets (Cyanoramphus novaezelandiae), as well as eastern rosellas (Platycercus eximius), an introduced species that is now common throughout the North Island, for BFDV. Out of all species and populations sampled (786 individuals), we found 16 BFDV-positive red-fronted parakeets from Little Barrier Island/Hauturu, seven eastern rosellas from the Auckland region, and eight yellow-crowned parakeets from the Eglinton Valley in the South Island. The full genomes of the viral isolates from the red-fronted parakeets share 95-97 % sequence identity to those from the invasive eastern rosellas and 92.7-93.4 % to those isolates from the South Island yellow-crowned parakeets. The yellow-crowned parakeet BFDV isolates share 92-94 % sequence identity with those from eastern rosellas. The low level of diversity among all BFDV isolates from red-fronted parakeets could suggest a more recent infection among these birds compared to the yellow-crowned parakeets, whereas the diversity in the eastern rosellas indicates a much more established infection. Pro-active screening and monitoring of BFDV infection rates in aviaries as well as in wild populations are necessary to limit the risk of transmission among threatened and endangered parrot populations in New Zealand.

A new isolate of beak and feather disease virus from endemic wild red-fronted parakeets (Cyanoramphus novaezelandiae) in New Zealand

Psittacine beak and feather disease (PBFD) is a viral disease distributed worldwide with a potentially critical impact on many rare parrots. While efforts have been made to determine its prevalence in wild and captive psittacines, only limited work has been done to document complete genomes of its causative agent, beak and feather disease virus (BFDV). Here, we describe five full genomes of BFDV isolated from wild specimens of an endemic New Zealand parrot, the red-fronted parakeet (Cyanoramphus novaezelandiae). The isolates share >99% nucleotide similarity amongst themselves and approximately 91-92% similarity to BFDV isolates from southern Africa, Europe and Australia. A maximum-likelihood (ML) phylogenetic tree including 42 other full-genome sequences indicated that the five isolates from red-fronted parakeets represent an undescribed genotype of BFDV. These isolates are evolutionarily most closely related to the Cacatuini isolates from Thailand and the Lorinae isolates from Australia in the rep gene ML tree; however, in the cp ML tree, the evolutionary relationship is closer to viruses found in the Psittacini.

A unique isolate of beak and feather disease virus isolated from budgerigars (Melopsittacus undulatus) in South Africa

Beak and feather disease virus (BFDV), the causative agent of psittacine beak and feather disease (PBFD) infects psittaciformes worldwide. We provide an annotated sequence record of three full-length unique genomes of BFDV isolates from budgerigars (Melopsittacus undulatus) from a breeding farm in South Africa. The isolates share >99% nucleotide sequence identity with each other and approximately 96% nucleotide sequence identity to two recent isolates (Melopsittacus undulatus) from Thailand but only between 91.6 and 86.6% identity with all other full-length BFDV sequences. Maximum-likelihood analysis and recombination analysis suggest that the South African budgerigar BFDV isolates are unique to budgerigars, are non-recombinant in origin, and represent a new genotype of BFDV.

Beak and feather disease virus infection in cockatiels (Nymphicus hollandicus)

Psittacine beak and feather disease is known to occur in a wide range of psittacine species; however, there are no scientific or credible anecdotal reports of psittacine beak and feather disease occurring in the cockatiel (Nymphicus hollandicus) despite it being one of the world's most commonly kept companion bird species. Consequently, this has resulted in speculation that the species may have some innate resistance to beak and feather disease virus (BFDV) infection. To investigate this hypothesis we conducted a survey of cockatiels (n=88) at commercial aviaries to investigate whether BFDV infection occurs in cockatiels, and found that all birds were virus-free by polymerase chain reaction and haemagglutination assay and had no detectable antibody titre by haemagglutination-inhibition assay. In addition to this, we sequenced the genome of two BFDV isolates obtained from diseased cockatiel feathers and performed cross-reactivity assays using virus eluted from these feathers and sera from naturally immune psittacine birds. Serological cross-reactivity results and phylogenetic analysis of the nucleotide sequences indicated that the cockatiel virus isolates were serologically and genetically different to other BFDV isolates. This is the first paper to report evidence of an antigenically distinct BFDV in psittacine birds.

Genetic diversity of the Rep gene of beak and feather disease virus in South Africa

A study on the genetic variation of Beak and feather disease virus (BFDV) isolates in South Africa was performed by amplifying and sequencing a region within the ORF1 of the genome. Six different BFDV isolates were found in 15 psittacine species from 6 regions within South Africa, representing three unique isolates and three isolates that clustered into a budgerigar lineage (BG) previously described.

Comparitive sensitivity of polymerase chain reaction diagnosis of psittacine beak and feather disease on feather samples, cloacal swabs and blood from budgerigars (Melopsittacus undulates, Shaw 18005)

A longitudinal study was performed in order to investigate virus excretion and viraemia during a clinical outbreak of the psittacine beak and feather disease in budgerigars (Melopsittacus undulatus). Viral nucleic acid was detected in feathers, cloacal swabs and blood samples. Overall, beak and feather disease virus (BFDV) DNA was detected most commonly in feather samples, followed by cloacal swabs, and least frequently from blood samples. In most cases the viraemia was short lived and correlated with clinical signs, such as feather abnormalities. Sequence analysis of the polymerase chain reaction fragment amplified from the replication-associated gene (ORF V1) indicated a close relationship with other BFDV isolates. Overall the highest level of nucleotide identity was found with the ORF V1 of another budgerigar isolate. Our results suggest that feather samples and cloacal swabs should be taken for polymerase chain reaction diagnosis to determine the presence of BFDV in an aviary, but that detection in these samples may not correlate well with psittacine beak and feather disease.

Evidence of unique genotypes of beak and feather disease virus in southern Africa.

Psittacine beak and feather disease (PBFD), caused by Beak and feather disease virus (BFDV), is the most significant infectious disease in psittacines. PBFD is thought to have originated in Australia but is now found worldwide; in Africa, it threatens the survival of the indigenous endangered Cape parrot and the vulnerable black-cheeked lovebird. We investigated the genetic diversity of putative BFDVs from southern Africa. Feathers and heparinized blood samples were collected from 27 birds representing 9 psittacine species, all showing clinical signs of PBFD. DNA extracted from these samples was used for PCR amplification of the putative BFDV coat protein (CP) gene. The nucleotide sequences of the CP genes of 19 unique BFDV isolates were determined and compared with the 24 previously described sequences of BFDV isolates from Australasia and America. Phylogenetic analysis revealed eight BFDV lineages, with the southern African isolates representing at least three distinctly unique genotypes; 10 complete genome sequences were determined, representing at least one of every distinct lineage. The nucleotide diversity of the southern African isolates was calculated to be 6.4% and is comparable to that found in Australia and New Zealand. BFDVs in southern Africa have, however, diverged substantially from viruses found in other parts of the world, as the average distance between the southern African isolates and BFDV isolates from Australia ranged from 8.3 to 10.8%. In addition to point mutations, recombination was found to contribute substantially to the level of genetic variation among BFDVs, with evidence of recombination in all but one of the genomes analyzed.

Genetic Diversity of Beak and Feather Disease Virus Detected in Psittacine Species in Australia

The complete nucleotide (nt) sequence of eight isolates of beak and feather disease virus (BFDV) obtained from a range of psittacine species with psittacine beak and feather disease (PBFD) from throughout Australia were compared with the sequences of two BFDV isolates previously reported from Australia (BFDV-AUS) and America (BFDV-USA), respectively. All isolates had the same basic structure including the position of the open reading frames, the hairpin structure between ORF1 and ORF2, the nonanucleotide motif (TAGTATTAC) therein, the three motifs of Rep protein encoded from ORF1 and involved in rolling circle replication, and the P-loop motif previously described, but the genome size of the eight isolates ranged from 1992 to 2018 nt. Overall nt identity of the isolates compared to BFDV-AUS ranged from 84 to 97%; the variation was due to a combination of point mutations and a number of deletions and insertions ranging from 1 to 17 nt in size detected in both coding and noncoding regions. The identity of the nt sequence of ORF2 compared to BFDV-AUS varied from 80 to 99%, while the identity of the deduced amino acid sequences varied from 73 to 99%. Phylogenetic analysis grouped the isolates into four clusters but there were no apparent regional differences or differences related to the psittacine species of origin. While seven ORFs with the potential to encode proteins greater than 8.7 kDa were detected in the BFDV-AUS isolate described previously, only three of these ORFs were detected in all 10 BFDV isolates for which sequence data were available. The three ORFs were ORF1 that presumably encodes the Rep protein, ORF2 presumably the major capsid protein, and the ORF previously designated ORF5. The ORF5 was of two size classes in different isolates, 303 and 474 nt, and only the first 303 nt of the viruses with an ORF of 474 nt were common to the other isolates.

A universal polymerase chain reaction for the detection of psittacine beak and feather disease virus

A universal PCR assay was designed that consistently detected psittacine beak and feather disease virus (BFDV) in psittacine birds affected with psittacine beak and feather disease (PBFD) from different geographic regions across Australia. Primers within open reading frame 1 (ORF1) of the BFDV genome consistently amplified a 717 bp product from blood and/or feathers of 32 birds with PBFD lesions. The PCR did not amplify a product from the feathers or blood from 7 clinically normal psittacine birds. Primers based on regions outside of ORF1 did not consistently produce a PCR product, suggesting there was some genomic variation outside ORF1. The amplified ORF1 PCR products of 10 BFDV isolates, from different psittacine species and from various regions around Australia, were cloned and comparative DNA sequence analysis demonstrated 88–99% of the ORF1 fragments. The derived amino acid sequences of the amplified ORF1 fragments demonstrated similar identity between all 10 isolates. Within ORF1, there was complete conservation of the putative nucleotide binding site and marked conservation of 2 other motifs previously identified as essential components of the replication-associated proteins of other circoviruses and geminiviruses.