Pigeon Circovirus Research Articles

The pigeon circovirus evolution, epidemiology and interaction with the host immune system under One Loft Race rearing conditions

This study was aimed to investigate the frequency of PiCV recombination, the kinetics of PiCV viremia and shedding and the correlation between viral replication and host immune response in young pigeons subclinically infected with various PiCV variants and kept under conditions mimicking the OLR system. Fifteen racing pigeons originating from five breeding facilities were housed together for six weeks. Blood and cloacal swab samples were collected from birds every seven days to recover complete PiCV genomes and determine PiCV genetic diversity and recombination dynamics, as well as to assess virus shedding rate, level of viremia, expression of selected genes and level of anti-PiCV antibodies. Three hundred and eighty-eight complete PiCV genomes were obtained and thirteen genotypes were distinguished. Twenty-five recombination events were detected. Recombinants emerged during the first three weeks of the experiment which was consistent with the peak level of viremia and viral shedding. A further decrease in viremia and shedding partially corresponded with IFN-γ and MX1 gene expression and antibody dynamics. Considering the role of OLR pigeon rearing system in spreading infectious agents and allowing their recombination, it would be reasonable to reflect on the relevance of pigeon racing from both an animal welfare and epidemiological perspective.

Sequencing of pigeon circovirus and the first report of identification of beak and feather disease virus in clinical specimens of domestic pigeons.

An internationally recognized syndrome that leads to deaths among domestic and ornamental pigeons, particularly after racing, is young pigeon disease syndrome (YPDS). Pigeon circovirus (PiCV) is regarded as one of the potential factors contributing to the occurrence of YPDS. This survey was conducted to determine the prevalence of PiCV infection and molecularly characterize the PiCV in pigeons suspected of YPDS. Eighty fecal samples were collected from 80 diseased pigeons (exhibiting symptoms such as lethargy, weight loss, crop stasis, vomiting and diarrhea) from 20 lofts in different areas of Ahvaz, Iran. Also, 20 fecal samples were obtained from 20 clinically healthy pigeons. The nested broad spectrum polymerase chain reaction test was done to identify the circovirus, using primers targeting part of the replication-associated protein gene with 350 bp, and several positive samples were sequenced. This study showed that PiCV was detected in 86 out of the 100 samples (86.00%). Two types of circoviruses were determined in the samples. One type of the detected circoviruses was PiCV which based on phylogenetic analysis had high genetic similarity with A, B, G and H genotypes of PiCV. The other type of detected circoviruses was closely related to beak and feather disease virus (BFDV) which causes one of the most significant viral diseases in psittacine birds. This is the first report of BFDV identification in pigeons.

Australasian Pigeon Circoviruses Demonstrate Natural Spillover Infection.

Pigeon circovirus (PiCV) is considered to be genetically diverse, with a relatively small circular single-stranded DNA genome of 2 kb that encodes for a capsid protein (Cap) and a replication initiator protein (Rep). Australasia is known to be the origin of diverse species of the Order Columbiformes, but limited data on the PiCV genome sequence has hindered phylogeographic studies in this species. To fill this gap, this study was conducted to investigate PiCV in 118 characteristic samples from different birds across Australia using PCR and sequencing. Eighteen partial PiCV Rep sequences and one complete PiCV genome sequence were recovered from reservoir and aberrant hosts. Phylogenetic analyses revealed that PiCV circulating in Australia was scattered across three different subclades. Importantly, one subclade dominated within the PiCV sequenced from Australia and Poland, whereas other PiCV sequenced in this study were more closely related to the PiCV sequenced from China, USA and Japan. In addition, PiCV Rep sequences obtained from clinically affected plumed whistling duck, blue billed duck and Australian magpie demonstrated natural spillover of PiCV unveiled host generalist characteristics of the pigeon circovirus. These findings indicate that PiCV genomes circulating in Australia lack host adapted population structure but demonstrate natural spillover infection.

Rapid detection of pigeon Megrivirus using TaqMan real-time PCR technology

Megriviruses have been identified from fecal samples in wild pigeons in Hong Kong (China) and Hungary. In this study, the genomic sequences of pigeon Megriviruses (PiMeVs) were downloaded from GenBank and compared. Based on the genetic comparison results, a pair of primers and TaqMan probe were designed based on the conserved sequences of the 3C gene (located in the P3 gene coding region), and a TaqMan real-time PCR method (TaqMan-qPCR) was established. The standard curve of the TaqMan-qPCR had an axial intercept of 39.74 and a slope of -3.2475 with a linear correlation (R2) of 1.00 and an efficiency of 103.2%. No cross-amplification signal was found from other pigeon viruses (such as avian influenza virus, pigeon paramyxovirus type I, pigeon torque teno virus, pigeon adenovirus, and pigeon circovirus). The limit of detection concentration was 53.6 copies/μL. The intra- and interassay results were less than 1.0% based on the reproducibility test. Furthermore, field samples investigation by the established TaqMan-qPCR method showed that positive signals can be found from racing pigeon fecal samples and embryos. Thus, our data suggested that this visible TaqMan-qPCR method is sensitive, specific, and reproducible. Moreover, we first confirmed the presence of pigeon Megrivirus infection in racing pigeon embryos, indicating that the virus may be vertically transmitted. This study provides a reference basis for further understanding the epidemiology of PiMeVs.

Lesions and viral loads in racing pigeons naturally coinfected with pigeon circovirus and columbid alphaherpesvirus 1 in Australia.

Columbid alphaherpesvirus 1 (CoHV1) is associated with oral or upper respiratory tract lesions, encephalitis, and occasional fatal systemic disease in naive or immunosuppressed pigeons. Clinical disease is often reported with CoHV1 and coinfecting viruses, including pigeon circovirus (PiCV), which may cause host immunosuppression and augment lesion development. A natural outbreak of CoHV1 and PiCV coinfection occurred in a flock of 60 racing rock pigeons (Columba livia), in which 4 pigeons succumbed within 7 d of clinical onset. Lesions included suppurative stomatitis, pharyngitis, cloacitis, meningitis, and tympanitis, with eosinophilic intranuclear inclusion bodies consistent with herpesviral infection. In addition, large numbers of botryoid intracytoplasmic inclusion bodies were present in the skin, oral mucosa, and bursa of Fabricius, suggestive of circoviral infection, which was confirmed by immunohistochemistry. The concurrent viral load of CoHV1 and PiCV was high in liver, oropharynx, and bursa of Fabricius. We found PiCV in oro-cloacal swabs from 44 of 46 additional birds of variable clinical status, PiCV alone in 23 birds, and coinfection with CoHV1 in 21 birds. Viral copy numbers were significantly higher (p < 0.0001) for both viruses in clinically affected pigeons than in subclinical qPCR-positive birds. The CoHV1-induced lesions might have been exacerbated by concomitant PiCV infection.

A retrospective molecular investigation of selected pigeon viruses between 2018-2021 in Turkey.

A recent first detection of pigeon aviadenovirus-1 and pigeon circovirus co-infection associated with Young Pigeon Disease Syndrome (YPDS) in a pigeon flock in Turkey, prompted a study focused on documenting the distribution of Pigeon aviadenovirus (PiAdV-1 and PiAdV-2), Pigeon circovirus (PiCV), Columbid alphaherpesvirus 1 (pigeon herpesvirus (PiHV)) and Fowl aviadenovirus (FAdV) in the country. These viruses were selected as they are associated with severe disease in pigeons across the world. A total of 192 cloacal swabs were collected from young (<1 year old) pigeons from 16 different private pigeon flocks across Turkey, between 2018 and 2021 as part of routine diagnostic sampling. PiCV genetic material was the most frequently detected 4/16 (25%), PiAdV-1 and CoHV-1 DNA were both found in one flock each, while neither PiAdV-2 and FAdV were detected in any of the studied pigeon flocks. PiCV and PiHV genetic material were both detected in the same pigeon flock’s cloacal samples as a co-infection with the identification of PiHV being a first in Turkey.

Pigeon Rotavirus A as the cause of systemic infection in juvenile pigeons (young pigeon disease).

Recent investigations suggested pigeon associated Rotavirus Typ A genotype G18P[17] (RVA) as a causative agent of the classical 'young pigeon disease' (YPD). YPD was first described in the late 1980 s as an acute, mainly seasonally recurring disorder of mostly juvenile domestic pigeons (Columba livia) with clinical signs such as anorexia, dairrhea, vomiting, congested crops, weight loss and occasionally mortality. Various studies in the past indicated a multifactorial nature of YPD. Several pathogens, such as pigeon circovirus 1, avian adenoviruses and Escherichia coli were also suggested, but none of these could reproduce the disease experimentally. However, the impact of other pathogens on the clinical development of YPD cannot be excluded and requires further investigation. This present review summarizes available information on RVA-induced disease in pigeons, its association with YPD, the transmission, and diagnosis of the infection, and on prophylactic strategies to prevent RVA outbreaks.

Development and applications of a TaqMan based quantitative real-time PCR for the rapid detection of Pigeon circovirus (PiCV)

TaqMan probe based quantitative polymerase reaction (TaqMan qPCR) is a robust and reliable technique for detecting and quantifying target DNA copies. Quantitative molecular diagnosis of genetically diverse single stranded DNA (ssDNA) virus such as Pigeon circovirus (PiCV) can be challenging owing to difficulties in primer binding or low abundance of template DNA copies in clinical specimens. Several methods have been described for the detection of PiCV, being qPCR the most simple and reliable. As far as is known, two qPCR systems described until now are based on SYBR green. This study reports development and validation of a highly sensitive TaqMan qPCR targeted to Rep for the detection of highly diverse PiCV in pigeon samples with excellent reproducibility, specificity, and sensitivity. The limit of detection was determined as low as 2 (two) plasmid copies. Estimations of 100 % specificity and 100 % sensitivity were obtained based on the qPCR results with panel of 60 samples (known PiCV positive, n = 30; known PiCV negative, n = 20; samples positive to Beak and feather disease virus (BFDV), n = 5 and samples positive to canine circovirus, n = 5). Co-efficient of variation (CV) for Ct values ranged between 0.27 % and 0.78 % in the same assay and 1.84–2.87 % in different assays.

Pigeon Circovirus over Three Decades of Research: Bibliometrics, Scoping Review, and Perspectives.

The pigeon circovirus (PiCV), first described in the literature in the early 1990s, is considered one of the most important infectious agents affecting pigeon health. Thirty years after its discovery, the current review has employed bibliometric strategies to map the entire accessible PiCV-related research corpus with the aim of understanding its present research landscape, particularly in consideration of its historical context. Subsequently, developments, current knowledge, and important updates were provided. Additionally, this review also provides a textual analysis examining the relationship between PiCV and the young pigeon disease syndrome (YPDS), as described and propagated in the literature. Our examination revealed that usages of the term ‘YPDS’ in the literature are characterizations that are diverse in range, and neither standard nor equivalent. Guided by our understanding of the PiCV research corpus, a conceptualization of PiCV diseases was also presented in this review. Proposed definitions and diagnostic criteria for PiCV subclinical infection (PiCV-SI) and PiCV systemic disease (PiCV-SD) were also provided. Lastly, knowledge gaps and open research questions relevant to future PiCV-related studies were identified and discussed.

Molecular detection and phylogenetic analysis of pigeon circovirus from racing pigeons in Northern China

BackgroundPigeon circovirus (PiCV) infections in pigeons (Columba livia) have been reported worldwide. Currently, pigeon racing is becoming increasingly popular and considered to be a national sport in China, and even, the greatest competitions of racing pigeons are taking place in China. However, there are still no epidemiologic data regarding PiCV infections among racing pigeons in China. The purpose of our study was to provide information of prevalence, genetic variation and evolution of PiCV from racing pigeons in China.ResultsTo trace the prevalence, genetic variation and evolution of PiCV in sick and healthy racing pigeons, 622 samples were collected from 11 provinces or municipalities in China from 2016 to 2019. The results showed that the positive rate of PiCV was 19.3% (120/622) at the sample level and 59.0% (23/39) at the club level, thus suggesting that the virus was prevalent in Chinese racing pigeons. A sequence analysis revealed that the cap genes of the PiCV strains identified in our study displayed a high genetic diversity and shared nucleotide homologies of 71.9%–100% and amino acid homologies of 71.7%–100%. 28 and 36 unique amino acid substitutions were observed in the Cap and Rep proteins derived from our PiCV strains, respectively. A cladogram representation of PiCV strains phylogeny based on 90 cap gene sequences showed that the strains in this study could be further divided into seven clades (A, B, C, E, G, H, and I) and some of them were closely related to worldwide strains from different types of pigeons. A large number of recombination events (31 events) were also detected in the PiCV genomes from Chinese racing pigeons.ConclusionsThese findings indicate that PiCV strains circulating in China exhibit a high genetic diversity and also contribute to information of prevalence, genetic variation and evolution of PiCV from racing pigeons in China.

Development and Applications of a Taqman Based Quantitative Real-Time PCR for the Rapid Detection of Pigeon Circovirus (PiCV)

Development and Applications of a Taqman Based Quantitative Real-Time PCR for the Rapid Detection of Pigeon Circovirus (PiCV)

A brief review of pigeon circovirus infection worldwide

A brief review of pigeon circovirus infection worldwide

First detection and molecular characterisation of a pigeon aviadenovirus A and pigeon circovirus co-infection associated with Young Pigeon Disease Syndrome (YPDS) in Turkish pigeons (Columba livia domestica).

Pigeon aviadenovirus A and Pigeon circovirus are both DNA viruses, infect and cause severe clinical diseases in pigeons. These viruses are associated with an immunosuppression syndrome similar to ‘Young Pigeon Disease Syndrome’ (YPDS). This study reports the identification of a natural co‐infection, with severe clinical signs (crop vomiting, watery diarrhoea, anorexia and sudden death) of Pigeon aviadenovirus A and Pigeon circovirus in a breeding pigeon flock in Central Anatolia, Turkey. Both viruses were isolated from pigeons pooled internal organs using primary chicken embryo kidney cell cultures (CEKC) and specific pathogen‐free (SPF) embryonated chicken eggs. Also, both viruses were identified by PCR amplification followed by Sanger sequencing whereas histopathological examination showed degenerated hepatocytes with basophilic intranuclear viral inclusions. As known, both viruses typically have similar transmission characteristics and common clinical manifestations; however, co‐infection may exacerbate the disease with devastating outcomes. This is the first report of its kind in Turkey for those viruses and is essential for the protection against these kinds of infections in pigeons.

Investigation of Lethal Concurrent Outbreak of Chlamydiosis and Pigeon Circovirus in a Zoo.

Simple SummaryThe present study aimed to investigate a lethal outbreak of chlamydiosis and pigeon circovirus (PiCV) infection in a zoo. A retrospective follow-up indicates that the lethal outbreak might be an independent episode. The high prevalence of PiCV positivity in the aviaries suggests that PiCV infection might play a key role in augmenting the lethality of chlamydiosis in birds. Persistently monitoring both pathogens and identifying potential PiCV carriers or transmitters might also help prevent lethal disease outbreaks.During the spring, an outbreak of sudden death involving 58 birds occurred in a zoo. Histopathological examinations revealed variable numbers of intracytoplasmic basophilic microorganisms in the macrophages, hepatocytes, and renal epithelium of most birds, along with occasional botryoid intracytoplasmic inclusion bodies within histiocytes in the bursa of Fabricius. Based on the results of histopathological examinations, immunohistochemical staining, transmission electron microscopy, and polymerase chain reactions, genotype B Chlamydia psittaci infection concurrent with pigeon circovirus (PiCV) was diagnosed. A retrospective survey, including two years before the outbreak and the outbreak year, of C. psittaci and PiCV infections of dead birds in the aviaries, revealed that the outbreak was an independent episode. The findings of this study indicate that concurrent infection with C. psittaci and PiCV might lead to lethal outbreaks of chlamydiosis, particularly Streptopelia orientalis. In addition, persistently monitoring both pathogens and identifying potential PiCV carriers or transmitters might also help prevent lethal disease outbreaks.

A Pilot Study Investigating the Dynamics of Pigeon Circovirus Recombination in Domesticated Pigeons Housed in a Single Loft.

Pigeon circovirus (PiCV) infects pigeon populations worldwide and has been associated with immunosuppression in younger pigeons. Recombination is a common mechanism of evolution that has previously been shown in various members of the Circoviridae family, including PiCV. In this study, three groups of pigeons acquired from separate lofts were screened for PiCV, and their genome sequence was determined. Following this, they were housed in a single loft for 22 days, during which blood and cloacal swab samples were taken. From these blood and cloacal swabs, PiCV genomes were determined with the aim to study the spread and recombination dynamics of PiCV in the birds. Genome sequences of PiCV were determined from seven pigeons (seven tested PiCV positive) before they were housed together in a loft (n = 58 sequences) and thereafter from the ten pigeons from blood and cloacal swabs (n = 120). These 178 PiCV genome sequences represent seven genotypes (98% pairwise identity genotype demarcation), and they share >88% genome-wide pairwise identity. Recombination analysis revealed 13 recombination events, and a recombination hotspot spanning the 3′ prime region, the replication-associated protein (rep) gene and the intergenic region. A cold spot in the capsid protein-coding region of the genome was also identified. The majority of the recombinant regions were identified in the rep coding region. This study provides insights into the evolutionary dynamics of PiCV in pigeons kept under closed rearing systems.

Pigeon rotavirus A genotype G18P[17]-associated disease outbreaks after fancy pigeon shows in Germany - a case series.

Pigeon rotavirus A (RVA) isolates of genotype G18P[17] are causing disease outbreaks and fatalities in pigeon lofts in Australia, Germany, Belgium, Denmark and USA since 2016. Most disease outbreaks have been reported from juvenile pigeons (Columba livia forma domestica). However, reports on RVA-associated disease outbreaks in fancy pigeons in connection with fancy pigeon shows in Germany are rare. Overall 18 pigeons (16 fancy pigeons and one racing pigeon from 9 pigeon fanciers, as well as one feral pigeon from a rescue center) were sent in for routine diagnostic necropsy including histopathologic, parasitologic and microbiologic examinations. Molecular biologic examinations for detection of RVA, circovirus, Usutu virus, West Nile virus and Chlamydia psittaci were also carried out on all pigeons. An accompanying questionnaire filled in by the senders was used to generate basic information on the affected pigeon lofts. Disease outbreaks in juvenile and adult pigeons were reported 7-14 days after fancy pigeon shows. One fancier who had previously vaccinated his pigeons with an autogenous pigeon RVA vaccine, noted no morbidity and mortality among his pigeons and thus sent in a healthy pigeon for diagnostic purposes. Reported clinical signs in the other pigeons were regurgitation, green slimy diarrhea, anorexia, apathy and death after 24 hours. Hepatic necrosis and detection of pigeon RVA isolates of genotype G18P[17] confirmed disease outbreaks caused by pigeon RVA in all pigeons, except for the vaccinated pigeon. Besides pigeon circovirus, which was detected in 15 of 18 pigeons, all other pathogens were singular findings. In disease outbreaks following fancy pigeon shows in juvenile and adult pigeons diagnostics should include pigeon RVA of genotype G18P[17].

Immunogenicity and Protective Activity of Pigeon Circovirus Recombinant Capsid Protein Virus-Like Particles (PiCV rCap-VLPs) in Pigeons (Columba livia) Experimentally Infected with PiCV.

Pigeon circovirus (PiCV) is the most recurrent virus diagnosed in pigeons and is among the major causative agents of young pigeon disease syndrome (YPDS). Due to the lack of an established laboratory protocol for PiCV cultivation, development of prophylaxis is hampered. Alternatively, virus-like particles (VLPs), which closely resemble native viruses but lack the viral genetic material, can be generated using a wide range of expression systems and are shown to have strong immunogenicity. Therefore, the use of VLPs provides a promising prospect for vaccine development. In this study, transfected human embryonic kidney (HEK-293) cells, a mammalian expression system, were used to express the PiCV capsid protein (Cap), which is a major component of PiCV and believed to contain antibody epitopes, to obtain self-assembled VLPs. The VLPs were observed to have a spherical morphology with diameters ranging from 12 to 26 nm. Subcutaneous immunization of pigeons with 100 µg PiCV rCap-VLPs supplemented with water-in-oil-in-water (W/O/W) adjuvant induced specific antibodies against PiCV. Observations of the cytokine expression and T-cell proliferation levels in spleen samples showed significantly higher T-cell proliferation and IFN- γ expression in pigeons immunized with VLPs compared to the controls (p < 0.05). Experimentally infected pigeons that were vaccinated with VLPs also showed no detectable viral titer. The results of the current study demonstrated the potential use of PiCV rCap-VLPs as an effective vaccine candidate against PiCV.

Isolation and identification of Circovirus in pigeon

The purpose of this study is first trial to detect of pigeon circovirus, so 1sr group include 100 cloacal swabs were collected 55 healthy and 45 ill pigeons, 36 yearlings and 64 adults, the 2nd group included organs was liver, spleen, bursa of Fabricius from 41 young pigeons 10-30 days old and bursa of Fabricius, liver, spleen from 28 dead in shell pigeon embryo in the 3rd group. DNA extracted from this samples and detection of virus DNA was attempt using polymerase chain reaction, after DNA amplification, the final products of the amplicon with 331 bp was cleared by using electrophoresis using agarose gel at concentration 2%. Results of viral DNA amplification were positive, which revealed as band in 331 bp the results showed that ill yearling pigeons recording high infectivity rate 66.7% compare with healthy yearling pigeons and adult once, the bursa of Fabricius samples of dead yearling pigeons recorded high prevalence 36.58% when compare with liver and spleen samples, DNA of pigeon circovirus high detected 60.71% in bursa of Fabricius of dead in shell pigeon embryo.in conclusion pigeon circovirus affected the racing pigeon in Mosul, Iraq.

Probiotic supplementation containing Bacillus velezensis enhances expression of immune regulatory genes against pigeon circovirus in pigeons (Columba livia).

In this study, we aimed to isolate and evaluate the efficacy of Bacillus velezensis as a probiotic and to assess its activity towards pigeons infected with pigeon circovirus (PiCV). Bacillus velezensis, isolated from pigeon faeces, was orally administered to pigeons for 60days. After pigeons were challenged with PiCV, the PiCV viral load and expression of indicator genes for innate immunity were detected in spleen tissue and faeces of pigeons. Bacillus velezensis significantly reduced the PiCV viral load in the faeces and spleen of pigeons 5days post-challenge (dpc). The mRNA expression levels of treated pigeons showed that interferon-gamma (IFN-γ), myxovirus resistance 1 (Mx1), and signal transducers and activators of transcription 1 (STAT1) genes were upregulated, whereas no expression of interleukin-4 (IL-4) was detected. Moreover, toll-like receptor 2 (TLR2) and 4 (TLR4) were significantly upregulated in probiotic-treated pigeons (P<0·05). This is the first report showing that probiotic supplementation can effectively enhance the T-helper type 1 immune response and decrease the PiCV viral loads in pigeons. This study proposes that the administration of a probiotic strain, B. velezensis, to pigeons can protect against PiCV infection.

Prevalence of pigeon rotavirus infections: animal exhibitions as a risk factor for pigeon flocks

A total of 289 cloacal swabs from pigeons from 29 different breeders in Germany were collected. In addition, samples from pigeons exhibited at shows were collected. The detailed health status of the pigeon flocks was recorded. Samples were analysed for the presence of the recently discovered pigeon rotavirus and pigeon circovirus. Pigeon rotavirus was found in 10.3% and pigeon circoviruses was found in 65.5% of sampled pigeon lofts. The study revealed a strong relationship between the attendance of shows and the occurrence of different clinical signs. The higher prevalence of pigeon rotavirus in exhibited animals indicates that exhibitions are a risk factor for the transmission of this pathogen.