Detection of novel adenovirus in sick pigeons

Identification and characterization of pigeon adenovirus 1 as an emerging pathogen in pigeons from Northern and Northwest China

BACKGROUND

In 2022, a new infectious disease characterized by severe acute hepatitis, sudden death, and high mortality among breeding pigeons, was reported in China.

RESULTS

In naturally infected pigeons, key necropsy findings comprised hepatic swelling with patchy hemorrhage and pericardial effusion. Histopathological examination further revealed degeneration, necrosis, and basophilic intranuclear inclusion bodies affecting hepatocytes, cardiomyocytes, and vascular endothelial cells. Transmission electron microscopy revealed a typical icosahedral virus structure and crystal-like arrangement of viral particles in the nucleus. Metagenomic next-generation sequencing (mNGS) of pericardial effusion samples revealed the presence of pigeon adenovirus. Sequencing analysis of the hexon and fiber-2 genes suggested that it constituted pigeon adenovirus 1 (PiAdV-1). The complete genome of CH/BJ/1/2022 was determined to be 48,071 nucleotides in length, with a 10-amino acid deletion in the fiber-2 gene at residues 627-636 and a 95-animo acid insertion in the 100 K gene at residue 75. The same disease was reproduced in pigeons by experimental infection.

CONCLUSION

Collectively, our analyses confirmed that the etiological agent was PiAdV-1, an emerging pathogen that causes severe acute hepatitis and high mortality in pigeons. This virus merits close attention because it could be catastrophic for the pigeon industry.

Isolation and identification of pigeon adenovirus 1 and analysis of its pathogenicity in pigeons and chickens

Pigeon adenovirus type 1 predominantly infects pigeons under 12 months of age (mainly 3-5 months old), causing major clinical symptoms such as vomiting, dehydration, and discharge of thin yellow feces. In February 2023, an outbreak of a pathogen with symptoms similar to pigeon adenovirus infections occurred on a pigeon farm in Shandong Province, which was eventually identified as pigeon adenovirus type 1. In this study, a strain of PiAdV-1 was isolated from naturally infected pigeons and named pigeon-adenovirus-1-isolate-CH-SD-2023, and the hexon gene sequence as amplified and analyzed using polymerase chain reaction (PCR). To assess its pathogenicity, PiAdV-1 viral fluids were injected intramuscularly into 4-month-old pigeons and 10-day-old chickens with specific pathogen free (SPF), respectively. The results showed that the pigeons in the experimental group exhibited watery feces, whereas the chickens showed typical symptoms of thin yellow feces. Histopathologic sections showed multiple organ damage, including severe liver and intestinal damage. Liver viral load peaked on the seventh day post-infection and then declined. Viral shedding was detectable in the cloaca from the third day of infection, peaked on the seventh day, and remained detectable until 15 days post-infection. Inflammatory cytokine levels were elevated, which may have been due to infection and innate immune response. In addition, the changes in inflammatory cytokines and the damage to the bone marrow suggested that the strain may have caused severe damage to their immune system. In conclusion, these findings add to our understanding of the pathogenicity of PiAdV-1 in pigeons and chickens. The developed model will be valuable for antiviral drug testing and vaccine evaluation to prevent and reduce the spread of PiAdV-1 in the poultry industry.

Characterization, phylogeny and prevalence of the coding-complete genomes of aviadenoviruses and siadenovirus in young racing pigeons

Adenoviruses are a concern for pigeon breeders due to their impact on animal health. Furthermore, they have been studied for nearly five decades and are one of the most studied viruses in pigeons. However, the number of complete genomic sequences of pigeon-infecting adenoviruses available is very low, and the pathogenic effect of these viruses on pigeons is still yet to be thoroughly explored. In this study, we describe the usage of high-throughput sequencing to identify and assemble genomic sequences of adenoviruses from pigeon samples. We were able to recover two coding-complete genomic sequences of members of Aviadenovirus genus, presumably belonging to Aviadenovirus columbidae species, and the first coding-complete genomic sequence of a member of Siadenovirus genus derived from a pigeon, genetically distinct from all other known species in this genus, which we proposed to be named Siadenovirus columbae. In addition, we designed quantitative PCR assay with TaqMan probes and digital droplet PCR to examine the potential link between the amount of pigeon adenovirus 2 (species Aviadenovirus columbidae) genome copies and the occurrence of enteropathy in young racing pigeons. The results of the quantitative analysis show that pigeon adenovirus 2 occurs in both healthy and diseased pigeons which is consistent with the previous findings. Further research is needed to assess how adenoviruses may influence enteric disease in racing pigeons.

Columbiform Pediatrics

Pigeons have been bred by humans for thousands of years as a source of food and feathers, as messengers, but also for their beauty, and more recently for sport. Pediatric medicine of pigeons has risen in importance given the interest at stake during international competitions. Young pigeons have a unique development and an increased sensitivity to both infectious and nutritional disorders compared with adults. Preventive medicine is of paramount importance and relies on measures targeting parents before breeding and chicks after hatching. Vaccination has been especially studied in pigeons.

Molecular docking and simulation studies of antiviral compounds against to fowl adenovirus type 4 receptor from - Psittacine bird - Melopsittacus undulates

The adenovirus family of adenoviridae includes mammalian adenoviruses (mastadenoviruses) and avian adenoviruses (avi-adenoviruses), which are known to cause cold or flu and HPS. A wide variety of afflicted birds, including chicken, pigeon, and psittacine species, have been reported to carry aviadenoviruses. Fowl adenovirus, which causes hydropericardium syndrome (FAdV). The disease is highly contagious and quickly spreads from one flock to another and from one farm to another using mechanical and horizontal transmission paths as well as contaminated litter. The drug Dehydroepiandrosterone (DHEA) is reported to have a significant binding affinity against the 7W83 receptors (-7.7 kcal/mol.) respectively. The study focuses on the therapeutic methodology development of Adenoviral infection. In order to discover useful combinations of the drugs in practice, molecular docking methods were also used to match fowl adenovirus protein with anti-viral compounds. To further support the docking effects, extensive molecular dynamics simulations were also used.

Phylogenetic analysis of pigeon adenovirus 1 in clinical specimens of domestic pigeons (Columba livia domestica) in Iran

An internationally identified syndrome that leads to deaths between domestic and ornamental pigeons, particularly after racing is young pigeon disease syndrome (YPDS). This study was conducted to determine the status of pigeon adenoviral infection and molecularly characterize the pigeon adenovirus in Ahvaz pigeons. Sixty stool samples of healthy pigeons (young pigeons and adult pigeons) and 60 stool samples of diseased pigeons (young and adults) with symptoms of lethargy, weight loss, crop stasis, vomiting and diarrhea were examined. Samples were screened for aviadenoviruses by polymerase chain reaction (PCR) assay and degenerated primers set to target the aviadenovirus polymerase (pol) gene were used which was designed in this study. Screening for pigeon adenovirus 1 (PiAdV-1) was performed using a primer pair that targeted the fiber gene of PiAdV-1. Out of 120 stool samples, six samples (5.00%) were positive for aviadenovirus. The results showed that independent from pigeons' age status, 5.00 and 3.33% of sick and of healthy pigeons were positive for PiAdV-1, respectively. Genomic sequencing revealed that the viruses detected in Ahvaz pigeons belonged to the PiAdV-1 genotype. The results in pigeons revealed a 98.10 - 99.53% nucleotide similarity when compared to other strains of PiAdV-1 (TR/SKPA20, P18-05523-6 and strain IDA4) formerly deposited in GenBank^® in Türkiye, Australia and The Netherlands. As far as the authors know, this was the first record of phylogenetic analysis of PiAdV-1 in Iran.

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.

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.

Common bacterial, viral, and parasitic diseases in pigeons (Columba livia): A review of diagnostic and treatment strategies

Pigeons (Columba livia) have been associated with humans for a long time now. They are raised for sport (pigeon race), exhibition (display of fancy breeds), food, and research. Most of the pigeons kept are Racing Homers, trained to compete in the pigeon race. Other breeds, such as Rollers, Nose Divers, Doneks are bred for their aerial abilities. Incorporation of a good preventive medicine program is one of the most critical factors in averting infectious diseases in pigeon flocks. This review summarizes the common bacterial, viral, and parasitic infections in pigeons. The different clinical signs, symptoms, diagnostic strategies, prevention, and treatments were described in this review. Current researches, molecular diagnostic assays, and treatment strategies such as vaccines and drug candidates were included. The information found in this review can provide insights for veterinarians and researchers studying pigeons to develop effective and efficient immunoprophylactic and diagnostic tools for pigeon diagnosis and therapeutics.

Adenovirus emergence in a red squirrel (Sciurus vulgaris) in Iberian Peninsula

Adenoviruses (AdV) are pathogens capable of infecting animals and humans leading to a wide spectrum of diseases. They have a widespread geographical dissemination and infect several species, including red squirrels (Sciurus vulgaris). In the Iberian Peninsula, there are no reports of infection of red squirrels by AdV. In this study, we report for the first time the detection of squirrel AdV in a red squirrel trapped in central Portugal. The phylogenetic analysis showed that the sequences obtained for the hexon and the penton base genes were similar to the Korean squirrel AdV strain and strongly divergent from the strains present in red squirrels in Europe. These findings indicate the emergence of a new strain circulating in Europe and raise concerns regarding the conservation of the red squirrel.

Development of a TaqMan-based real-time PCR for detecting duck adenovirus 3

Recently, a novel duck adenovirus (designated as duck adenovirus 3, DAdV-3) was discovered in Muscovy ducks, China. Here, we developed a TaqMan-based real-time PCR assay (qPCR) for the detection of DAdV-3 infection. After the optimization of the qPCR conditions, the lower limit of detection for DAdV-3 infection was 40.9 copies/μl. No cross-reactivity was observed with other duck-derived pathogens. Intra- and inter-assay variability was less than 2.30%. DAdV-3 was detected in embryos and newly hatched ducklings by qPCR assay, the findings provided evidence of possible vertical transmission of DAdV-3. The developed qPCR analysis showed high specificity, sensitivity, and reproducibility, thereby indicating that it can be used in future investigations on the pathogenesis and epidemiology of DAdV-3.