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Background Diseases caused by polyomaviruses and circoviruses in parrots were first described in the 1980s. Then they began to be diagnosed in other orders of birds, including Passeriformes, such as Atlantic canaries ( Serinus canaria ) and estrildid and fringillid finches. Over time, these viruses have also been found in an increasing number of captive and wild passerine species. The aim of the study was to assess the occurrence of these viruses in captive and wild Passeriformes in Poland, and the transmission of polyomaviruses and circoviruses through eggs in Atlantic canaries and Bengalese munias ( Lonchura striata domestica ). Results Nested PCR tests for avian polyomavirus (APyV) and circovirus (CV) were carried out on organ samples from 331 captive and wild birds belonging to 45 species, necropsied between 2006 and 2024. Additionally, 112 samples of eggs and dead chicks of Atlantic canaries and Bengalese munias from two aviaries with breeding problems were examined. Positive PCR results for APyV were found in 98 birds (29.6%), while CV DNA was detected in 152 birds (45.9%). In 104 wild birds examined, APyV was found in 13 (12.5%) and CV in 35 (33.7%) individuals. In 227 captive birds, APyV was found in 85 (37.4%) and CV in 117 (51.5%) individuals. Co-infections with both viruses were found in 25.1% of captive birds and 7.7% of wild birds. Negative results for both APyV and CV were found in 145 (43.8%) birds tested. In Atlantic canaries, CV DNA was identified in 79% of unfertilized eggs and 59% of embryos examined. In Bengalese munias, CV DNA was identified in 62.5% of unfertilized eggs and in all chicks examined. APyV DNA was not detected in eggs or embryos of canaries and Bengalese munias, nor in any Bengalese munia chicks or canary chicks younger than 7 days. Conclusions Avian polyomaviruses and circoviruses are widespread in the population of captive and wild passerines in Poland, and a higher percentage of birds are infected with circovirus than with polyomavirus. Co-infections are more commonly observed in captive passerine birds than in wild passerine birds. Vertical transmission occurs for circoviruses, but not for polyomaviruses, in Atlantic canaries and Bengalese munias.

Polyomaviruses are nonenveloped icosahedral viruses with a double-stranded circular DNA containing approximately 5000 bp and 5–6 open reading frames. In contrast to mammalian polyomaviruses (MPVs), avian polyomaviruses (APVs) exhibit high lethality and multipathogenicity, causing severe infections in birds without oncogenicity. APVs are classified into 10 major species: Adélie penguin polyomavirus, budgerigar fledgling disease virus, butcherbird polyomavirus, canary polyomavirus, cormorant polyomavirus, crow polyomavirus, Erythrura gouldiae polyomavirus, finch polyomavirus, goose hemorrhagic polyomavirus, and Hungarian finch polyomavirus under the genus Gammapolyomavirus. This paper briefly reviews the genomic structure and pathogenicity of the 10 species of APV and some of their differences in terms of virulence from MPVs. Each gene’s genomic size, number of amino acid residues encoding each gene, and key biologic functions are discussed. The rationale for APV classification from the Polyomavirdae family and phylogenetic analyses among the 10 APVs are also discussed. The clinical symptoms in birds caused by APV infection are summarized. Finally, the strategies for developing an effective vaccine containing essential epitopes for preventing virus infection in birds are discussed. We hope that more effective and safe vaccines with diverse protection will be developed in the future to solve or alleviate the problems of viral infection.

Avian polyomavirus (APV) infection, also called as budgerigar fledgling disease (BFD) causes various health problems in many psittacine species which may cause untimely death. The aims of this study were to investigate, for the first time, the detection, molecular characterization and phylogenetic analysis of avian polyomavirus (APV) in Pakistani psittacine birds. In an aviary a disease similar to APV was found and 90% of the nestlings died within a few weeks. Seven to ten-day-old parrot nestlings (n = 3) from the aviary were presented with feather abnormalities, plumage defect and were clinically depressed. Birds died at 11th, 14th and 16th day of age. Samples of hearts, livers, spleen, feathers and kidneys were collected from the dead birds. Samples were analyzed for the presence of APV DNA by using PCR. APV VP1 gene was partially sequenced, and phylogenetic analysis was performed. The APV strain was similar to those previously reported in other areas of the world. The results of this investigation indicate presence of a high frequency of APV infections in psittacine birds in Pakistan.

The griffon vulture (Gyps fulvus fulvus) is a scavenger species that plays a vital ecological role in carrion removal. Successful survival and reproduction in captive and wildlife conditions require optimal physical status and plumage integrity. Nutritional and environmental factors, systemic diseases, and various etiological agents can influence feather alterations. Although frequently documented in captive psittacine species, feather abnormalities are extremely rare in wild birds. Since 2020, two free-living griffon vultures in northeastern Italy have been found in poor physical condition, unable to fly due to partial feather loss and malformation of remiges and rectrices. Histopathologic examination of follicles and peri-follicular tissue revealed atrophy, keratin replacement, vasculitis, and calamus dystrophy with lymphohistiocytic perivasculitis. Immunohistochemical and ultrastructural analysis identified the presence of virus-like particles in epithelial and inflammatory cells. Although virome analysis did not confirm the presence of this virus in pooled affected samples, this study provides the first report of an emerging plumage disorder in free-ranging griffon vultures, which requires further characterization.

Disease surveillance is vital to the management of New Zealand's endemic and threatened avian species. Three infectious agents that are potential threats to New Zealand's endemic birds include avian polyomavirus (APV), beak and feather disease virus (BFDV), and avian malaria. All three agents have been reported in New Zealand; however, possible reservoir populations have not been identified. In this communication, we report the first study of APV, BFDV, and avian malaria in introduced adult exhibition budgerigars (Melopsittacus undulatus) in New Zealand. Blood samples were collected from 90 living adult budgerigars from three breeding locations in the North Island of New Zealand. An overall APV prevalence of 22% was determined using a broad-spectrum nested PCR that amplified the major capsid protein VP1 gene of polyomavirus. Phylogenetic analysis of the VP1 gene revealed a unique isolate of APV, which had a sequence divergence of 32% to previously reported budgerigar fledgling disease strains and 33% to the recently reported New Zealand finch isolate. All of the budgerigars sampled were found to be PCR negative for BFDV, and an overall prevalence of 30% was detected by PCR for avian malaria. Sequencing revealed the presence of ubiquitous malarial strains and also the potentially destructive Plasmodium relictum strain. The results of this study suggest that both APV and avian malaria are present in New Zealand adult budgerigars, and our study highlights the need for further studies to determine whether these pathogens in captive bird populations may be a threat or spill over into New Zealand's endemic and threatened avifauna and whether prevention and control methods need to be implemented. Un estudio de enfermedades de tres poblaciones reproductoras de periquitos australianos (Melopsittacus undulatus) de exhibición en Nueva Zelanda revela una alta prevalencia de una infección por un nuevo poliomavirus y por la malaria aviar. La vigilancia de enfermedades es vital para el manejo de las especies aviares endémicas y amenazadas de Nueva Zelanda. Tres agentes infecciosos que son amenazas potenciales para las aves endémicas de Nueva Zelanda incluyen al poliomavirus aviar (APV), el virus de la enfermedad del pico y plumas (BFDV), y la malaria aviar. Los tres agentes se han reportado en Nueva Zelanda, sin embargo, no han sido identificadas poblaciones de posibles reservorios. En este artículo se presenta el primer estudio de poliomavirus aviar, del virus del pico y las plumas y de la malaria aviar en periquitos australianos (Melopsittacus undulatus) adultos de exhibición introducidos a Nueva Zelanda. Se recolectaron muestras de sangre de 90 periquitos adultos vivos de tres lugares de cría en la Isla Norte de Nueva Zelanda. Se determinó una prevalencia general de poliomavirus aviar de 22% utilizando un método de PCR anidado que amplifica el gene de la proteína principal de la cápside VP1 del poliomavirus. El análisis filogenético del gene VP1 reveló un aislamiento único de poliomavirus, que tenía una divergencia de 32% en su secuencia en comparación con las cepas previamente asociadas con la enfermedad de la muda francesa de los periquitos (budgerigar fledgling disease) y de un 33% con un aislamiento de pinzón de Nueva Zelanda reportado recientemente. Todos los periquitos muestreados resultaron ser negativos por PCR para la enfermedad del pico y las plumas, y se detectó una prevalencia general del 30% por PCR para la malaria aviar. La secuenciación reveló la presencia de cepas de malaria ubicuas y de una cepa de Plasmodium relictum que es potencialmente destructiva. Los resultados de este estudio sugieren que tanto poliomavirus aviar y la malaria aviar están presentes en periquitos australianos adultos de Nueva Zelanda y ponen de manifiesto la necesidad de realizar más estudios para determinar si estos patógenos presentes en poblaciones de aves en cautiverio pueden ser una amenaza o puedan extenderse a las especies endémicas y fauna aviar amenazada de Nueva Zelanda y si se requieren aplicar métodos de prevención y control.

The collection of baseline health data is an essential component of an endangered species conservation program. As for many wildlife species, there are minimal health data available for wild populations of the endangered Carnaby’s cockatoo (Zanda latirostris). In this study, 426 wild Carnaby’s cockatoo nestlings were sampled from nine breeding sites throughout the range of the species over an 11-year period. In addition to a physical examination, samples were collected to test for hematologic and biochemical parameters, psittacine beak and feather disease virus (BFDV), avian polyomavirus (APV), psittacine adenovirus, psittacine herpesvirus, Chlamydia, disease serology and endoparasites. Environmental sampling was performed to screen for BFDV and APV in nest hollows. Descriptive health data are presented for nestlings of this species, with BFDV, APV and Chlamydia infections reported. Reference intervals for hematologic and biochemical parameters are presented in three age groups, and factors affecting blood analytes and body condition index are discussed. This longitudinal dataset provides insights into health parameters for Carnaby’s cockatoo nestlings and a reference for future monitoring of breeding populations.

Avian polyomavirus (APV) is an emerging pathogen in many parts of the world responsible for causing significant mortality in captive psittacine birds. The virus spreads slowly, and transboundary movement of birds is one of the potential risk factors for the virus introduction in the naïve population. Bangladesh allows the import of birds, however there is currently no surveillance to screen for APV. Since we confirmed beak and feather disease virus (BFDV) infection in the captive population in our earlier investigation, we hypothesized that APV may also be circulating in Bangladesh. Feather samples were collected from 100 birds (90 psittacine and 10 non-psittacine). The polymerase chain reaction (PCR) was used to detect viral DNA together with sequencing and phylogenetic analysis. This first pilot study confirmed the presence (7%, 7/100) of APV in captive psittacine birds of Bangladesh and almost half (4%, 4/100) of the APV positive birds had the BFDV co-infection. All the PCR-positive birds were asymptomatic and found in live bird markets (LBMs). No significant variation was observed in the detection rate considering species ( P  = 0.94), age ( P  = 0.39) or sex ( P  = 0.55) of birds. According to the results of the phylogenetic study, the APV isolates found in Bangladesh appear to be unrelated to isolates from other geographical areas. These findings provide an evidence of APV circulating in Bangladesh, with or without the co-infection of BFDV. Additional studies are needed to investigate the occurrence of APV/BFDV co-infection in the larger population of Bangladesh and in countries where transboundary bird interaction with Bangladesh may be possible.

Avian polyomavirus (APV) and psittacine beak and feather disease virus (PBFDV) induce contagious and persistent diseases that affect the beaks, feathers, and immune systems of companion birds. APV causes hepatitis, ascites, hydropericardium, depression, feather disorders, abdominal distension, and potentially death. PBFDV can induce progressive beak deformity, feather dystrophy, and plumage loss. We conducted the first prevalence survey of both APV and PBFDV infections in companion birds in eastern Turkey. A total of 113 fresh dropping samples from apparently healthy companion birds were collected in a random selection. The dropping samples were analysed for PBFDV and APV by PCR. Positive samples were sequenced with the Sanger method. The sequence was confirmed through alignment and the phylogenetic tree generated through the maximum likelihood method computationally. PBFDV and APV were detected in a respective 48.7% and 23.0% of samples. Coinfection was found in 12.4% of the samples, these all being from budgerigars ( ). APV and PBFDV were detected in budgerigar and cockatiel ( ) samples. This report provides a foundation for future studies on the influence of these viruses on the health of companion birds. These high positive rates for both pathogens emphasise that healthy and in eastern Turkey may be prone to the emergence and spread of APV and PBFDV with subclinical potential.

Budgerigar fledgling disease (BFD) and psittacine beak and feather disease (PBFD) are caused by avian polyomavirus (APV) and psittacine beak and feather disease virus (PBFDV), respectively. These diseases frequently infect psittacine birds and result in similar clinical manifestations. In this study, we observed the prevalence of PBFDV infection and a dual infection of APV and PBFDV in a budgerigar ( Melopsittacus undulatus ) in Mainland China for the first time. One PBFDV isolate and two APV isolates were harvested using chicken embryos. Genetic characterization and phylogenetic analysis of the complete genome of the two APV isolates revealed nucleotide similarity ranging from 99.0% to 99.6% to other sequences in GenBank, and a 14-bp insertion was observed in the genome of one APV isolate. The results of complete genome analysis of the PBFDV isolate showed nucleotide similarity ranging from 83.0% to 95.0% with other PBFDV sequences in GenBank. Genetic characterization and phylogenetic analysis of the APV and PBFDV strains isolated in this study indicated that the isolates from China were closely related to their Japanese counterparts. The results of this study will help to identify molecular determinants and will aid further research on the prevention and control of APV and PBFD infection.

Avian polyomavirus infection in psittacines was diagnosed in tissues by the use of polymerase chain reaction (PCR) test. The tissues used in the procedure were either formalin-fixed tissues embedded in paraffin blocks or fresh tissues (heart, liver, and spleen) collected from the psittacines during necropsy. DNA was extracted from these tissues and was tested with the published primers for avian polyomavirus VP1 gene in the PCR that yielded an amplicon of 550 base pair size, which was then visualized by electrophoresis. The amplicon size was consistent with avian polyomavirus. The PCR test was found to be an effective method for identifying avian polyomavirus infection in both formalin-fixed, paraffin-embedded and fresh tissues from psittacine birds of different age groups.