Characterization of a new species of adenovirus in falcons

Raptor Pediatrics

Neonatal and juvenile raptors may differ from adults in their husbandry, disease predispositions, and medical therapies. There are differences between captive bred juveniles and those presented for rehabilitation to the wild, which must be taken into consideration for successful long-term outcomes. In captive settings, many metabolic and infectious diseases may be linked to problems with diet. The successful rehabilitation and release of wild raptor chicks requires special precautions beyond avoiding imprinting.

Isolation and Genetic Characterization of a Novel Adenovirus Associated with Mass Mortality in Great Cormorants (Phalacrocorax carbo)

High mortality in great cormorants (Phalacrocorax carbo) was registered on the Alakol Lake in eastern Kazakhstan in 2021 when about 20% of juveniles died. High-throughput sequencing revealed the presence of a putative novel cormorant adenovirus significantly divergent from known aviadenoviruses. We suggest that this cormorant adenovirus can be considered an emerging threat to the health and conservation of this species.

The first complete genome sequence and pathogenicity characterization of fowl adenovirus serotype 2 with inclusion body hepatitis and hydropericardium in China

Since 2015, fowl adenovirus (FAdV) has been frequently reported worldwide, causing serious economic losses to the poultry industry. In this study, a FAdV-2, namely GX01, was isolated from liver samples of chickens with hepatitis and hydropericardium in Guangxi Province, China. The complete genome sequence of GX01 was determined about 43,663 base pairs (bp) with 53% G+C content. To our knowledge, this is the first FAdV-2 complete genome in China. There was a deleting fragment in ORF25 gene. Phylogenetic analysis based on the hexon loop-1 gene showed that GX01 is most closely related to FAdV-2 strain 685. Pathogenicity experiment of GX01 in 3-day-old and 10-day-old specific-pathogen-free chickens showed that although no mortality was observed within 21 days post infection (dpi), strain GX01 significantly inhibited weight gain of infected chickens. Moreover, FAdV-2 was still detectable in the anal swabs of infected chickens at 21 dpi. Necropsy analysis showed that the main lesions were observed in liver, heart, and spleen. Of note, hepatitis and hydropericardium were observed in the infected chickens. In addition, massive necrosis of lymphocyte was observed in spleen of infected 3-days-old chickens. We concluded that FAdV-2 strain GX01 is capable of causing hepatitis and hydropericardium, which will make serious impact on the growth of chickens. Our research lays a foundation to investigate the molecular epidemiology and etiology of FAdV.

Adenoviral infection in 5 red-tailed hawks and a broad-winged hawk

Adenoviral infections among raptors are best described in falcons and are characterized most commonly by necrotizing hepatitis and splenitis; only one case has been reported in a hawk. Five red-tailed hawks (Buteo jamaicensis) and a broad-winged hawk (Buteo platypterus) had an adenoviral infection based on history, histopathology, negative-stain electron microscopy, and PCR. All birds had acute onset of illness resulting in death; 3 had evidence of a concurrent bacterial infection. Microscopically, all 6 birds had solitary, pale eosinophilic-to-amphophilic, intranuclear inclusion bodies within presumed hematopoietic cells in bone marrow and macrophages in spleen. Five of the 6 birds had similar inclusions within hepatocytes and Kupffer cells. All but one bird had severe bone marrow necrosis. There was moderate splenic necrosis (3 of 6) and mild-to-marked hepatic necrosis (4 of 6). Negative-stain electron microscopy demonstrated adenoviral particles in bone marrow (5 of 6), liver (1 of 5), and/or spleen (1 of 5). PCR was positive for adenovirus in bone marrow (3 of 5), liver (1 of 3), spleen (4 of 6), and/or intestinal contents (2 of 3). Viral DNA polymerase gene sequences clustered within the Siadenovirus genus. There was 99% nucleotide identity to one another and 90% nucleotide identity with the closest related adenovirus (Harris hawk, EU715130). Our case series expands on the limited knowledge of adenoviral infections in hawks. The splenic and hepatic necrosis, and particularly the hitherto unreported bone marrow necrosis, suggest that adenoviral infection is clinically relevant and potentially fatal in hawks.

Coding-Complete Genome Sequence of a Falcon aviadenovirus A Strain Associated with Necrotizing Hepatitis in an American Kestrel (Falco sparverius)

A necropsy was performed on an American kestrel (Falco sparverius) with necrotizing hepatitis associated with inclusion bodies, suggesting an adenovirus infection. A next-generation sequencing assay was conducted on the liver, and the coding-complete genome sequence of a Falcon aviadenovirus A strain was revealed.

Isolation and whole-genome sequencing of a novel aviadenovirus from owls in Japan

Adenoviruses have been reported to infect a variety of birds. Here, we isolated a novel adenovirus from the liver of a dead owl chick (Bengal eagle owl; Bubo bengalensis) at a raptor-breeding facility in Japan and determined the complete genome sequence of the virus. We performed necropsies on the dead owl chicks and found that they had enlarged livers, pericardial edema, and focal necrosis of the liver tissue. Transmission electron microscopy of the liver tissue revealed a virus-like structure, appearing as paracrystalline arrays in the nucleus, and immunohistochemical staining with anti-adenovirus antibodies showed positive reactions in hepatocytes and other cells. Attempts to isolate the virus from homogenized liver tissue of a dead owl chick showed a cytopathic effect on chicken-derived cultured cells after multiple blind passages. Further, we determined the complete genome sequence of this virus and performed phylogenetic analysis, revealing that this adenovirus belongs to the genus Aviadenovirus, forming a cluster with fowl and turkey aviadenoviruses. The amino acid sequence divergence between the DNA polymerase of this virus and its closest known adenovirus relative is approximately 29%, implying that this virus can be assigned to a new species in the genus Aviadenovirus. Based on our data, this novel owl adenovirus is a likely cause of fatal infections in owls, which may threaten wild and captive owl populations. Further, this virus is unique among raptor adenoviruses in that it infects chicken-derived cultured cells, raising the importance of further investigations to evaluate interspecies transmission of this virus.

Genomic characterization of psittacine adenovirus 2, a siadenovirus identified in a moribund African grey parrot (Psittacus erithacus)

Here, we report the complete genome sequence of psittacine adenovirus 2 from a moribund African grey parrot (Psittacus erithacus) with neurological signs and systemic inflammation. The complete siadenovirus genome is 25,386 bp in size. The results of genetic and phylogenetic analyses support its classification as a member of a novel species within the genus Siadenovirus. This study represents the first report of the genome sequence of an adenovirus from an African grey parrot.

A 24-Year-Old Sample Contributes the Complete Genome Sequence of Fowl Aviadenovirus D from the United States

Here, we report the complete genome sequence of fowl aviadenovirus D (FAdV-D) isolated from a preserved 24-year-old pancreas sample of a broiler chicken embryo. The results of the sequence showed that the viral genome is 44,079 bp long.

Isolation and molecular characterization of Fowl adenovirus strains in Black grouse: First reported case in Poland

This article describes the isolation, molecular characterization, and genotyping of two fowl adenovirus (FAdVs) strains with GenBank Accession numbers (MT478054, JSN-G033-18-L and MT478055, JSN-G033-18-B) obtained from the internal organs of black grouse (Lyrurus tetrix). This study also reveals the first confirmation of fowl adenovirus in Poland, supporting one of the hypotheses about the probability of fowl adenovirus interspecies transmission. The adenovirus strain sequences were investigated via phylogenetic analysis and were found to have an overall mean pairwise distance of 2.189. The heterogeneity, Relative Synonymous Codon Usage (RSCU), codon composition, and nucleotide frequencies were examined. Statistical analyses and Tajima’s test for the examined sequences were carried out. The Maximum Likelihood for the examined sequences substitutions was performed. The results of the sequence analysis identified MT478054, JSN-G033-18-L and MT478055, JSN-G033-18-B as strains of fowl adenovirus 2/11/D, with the Fowl adenovirus D complete sequence showing a 93% match. Wild birds may act as a natural reservoir for FAdVs and likely play an important role in the spreading of these viruses in the environment. The findings reported here suggest horizontal transmission within and between avian species.

Inclusion body hepatitis caused by Aviadenovirus in a tropical screech owl (Megascops choliba)

In 2016, tropical screech owl (Megascops choliba) (Tso) chicks were suddenly found dead in a Japanese breeding facility. We autopsied a 9-day-old Tso and discovered white spots scattered on the liver surface. Multifocal necrosis was diffused, and macrophages had infiltrated the necrotic hepatic lesions. Hepatocytes contained numerous intranuclear inclusion bodies. Immunohistochemical staining detected Adenovirus antigen only in the liver. Next, PCR and sequencing (LC536616) identified Tso Adenovirus (TsoAd). Basic Local Alignment Search Tool (BLAST) and phylogenic analyzes suggested TsoAd is an owl Aviadenovirus. Our study contributes to an improved understanding of infectious disease among captive raptors.

Vidovszky M, Rossi JL, Vicentini F, Harrach B, L. Kaján G. Identification of two novel adenoviruses in smooth-billed ani and tropical screech owl

Avian adenoviruses (AdVs) are a very diverse group of pathogens causing diseases in poultry and wild birds. Wild birds, endangered by habitat loss and habitat fragmentation in the tropical forests, are recognised to play a role in the transmission of various AdVs. In this study, two novel, hitherto unknown AdVs were described from faecal samples of smooth-billed ani and tropical screech owl. The former was classified into genus Aviadenovirus, the latter into genus Atadenovirus, and both viruses most probably represent new AdV species as well. These results show that there is very limited information about the biodiversity of AdVs in tropical wild birds, though viruses might have a major effect on the population of their hosts or endanger even domesticated animals. Surveys like this provide new insights into the diversity, evolution, host variety, and distribution of avian AdVs.

Detection of fowl adenovirus D strains in wild birds in Poland by Loop-Mediated Isothermal Amplification (LAMP)

BACKGROUND

The present study on the role of strains of adenovirus in wildlife reservoirs, and their prevalence is under exploration. In several previous studies, the presence of adenovirus strains in wild birds has been investigated. Worldwide distribution and outbreaks of adenovirus infections have been reported by many authors. The present study investigated the prevalence of FAdVs in 317 samples of different bird species from the northwestern region of Poland. An applied specific, sensitive, and efficient, without cross-reactivity loop-mediated isothermal amplification (LAMP) method to gauge the prevalence of fowl adenovirus strains in wild birds was developed and used.

RESULTS

The method was based on the sequence of the loop L1 HVR1-4 region of the hexon gene of the FAdV genome reference strains FAdV-2 KT862805 (ANJ02325), FAdV-3 KT862807 (ANJ02399) and FAdV-11 KC750784 (AGK29904). The results obtained by LAMP were confirmed by real-time PCR. Among 317 samples obtained from wild birds, eight FAdV isolates (2.52%) were identified and produced a cytopathic effect (CPE) in chicken embryo kidney cells (CEK). Three FAdV types belonging to species Fowl adenovirus D were detected, which were isolated from three adenovirus types 2/3/11, and have been confirmed in three mute swans (Cygnus olor), three wild ducks (Anas platyrhynchos), one owl (Strigiformes), and one common wood pigeon (Columba palumbus).

CONCLUSIONS

This study provides the first accurate quantitative data for the replication of fowl adenovirus strains in wild birds in Poland, indicating adenovirus interspecies transmission, and demonstrating the circulation of FAdVs in wild birds.

First experimental proof of Rotavirus A (RVA) genotype G18P[17] inducing the clinical presentation of 'young pigeon disease syndrome' (YPDS) in domestic pigeons (Columba livia)

Young pigeon disease syndrome (YPDS) is characterized as a seasonally occurring, acute and primarily enteric medical condition of mainly juvenile domestic pigeons (Columba livia) with highly variable mortality reaching more than 50%. Although the syndrome has been known in Europe for almost three decades, its aetiology remains largely obscure. Recently, a previously unknown pigeon-associated clade of Rotavirus A (RVA) genotype G18P[17] was detected in Europe and Australia in association with fatal diseases resembling YPDS. Here we show for the first time, that peroral inoculation of healthy juvenile homing pigeons with two genetically different cell culture isolates of RVA G18P[17] (10^6.3 foci-forming units per bird) induces an acute and self-limiting YPDS-like disease in all infected birds. Clinical signs included regurgitation, diarrhoea, congested crops, anorexia and weight loss, as described for naturally RVA-infected pigeons. In agreement with the original outbreaks, RVA isolate DR-7 induced more pronounced clinical signs as compared to isolate DR-5, indicating strain-dependent virulence factors to contribute to variable disease outcomes observed in the field. All inoculated birds developed rotavirus-reactive antibodies starting at seven days after inoculation. High levels of viral RNA and infectious virus were detectable in cloacal swabs and faecal samples already three days after inoculation. While shedding of infectious virus subsided within few days, moderate viral RNA levels were still detectable in cloacal swabs, faeces, and tissue samples at the end of the experiment three weeks after inoculation. Histopathological analysis at this time point revealed inflammatory lesions in spleens and livers of pigeons from both infected groups. In summary, we fulfilled Henle-Koch's postulates and confirmed RVA G18P[17] as a primary cause of YPDS-like diseases in domestic pigeons. By establishing an infection model, we provide a crucial tool for future research, such as identification of transmission routes and establishing vaccination regimes.

Faecal Virome Analysis of Wild Animals from Brazil

The Brazilian Cerrado fauna shows very wide diversity and can be a potential viral reservoir. Therefore, the animal's susceptibility to some virus can serve as early warning signs of potential human virus diseases. Moreover, the wild animal virome of this biome is unknown. Based on this scenario, high-throughput sequencing contributes a robust tool for the identification of known and unknown virus species in this environment. In the present study, faeces samples from cerrado birds (Psittacara leucophthalmus, Amazona aestiva, and Sicalis flaveola) and mammals (Didelphis albiventris, Sapajus libidinosus, and Galictis cuja) were collected at the Veterinary Hospital, University of Brasília. Viral nucleic acid was extracted, submitted to random amplification, and sequenced by Illumina HiSeq platform. The reads were de novo assembled, and the identities of the contigs were evaluated by Blastn and tblastx searches. Most viral contigs analyzed were closely related to bacteriophages. Novel archaeal viruses of the Smacoviridae family were detected. Moreover, sequences of members of Adenoviridae, Anelloviridae, Circoviridae, Caliciviridae, and Parvoviridae families were identified. Complete and nearly complete genomes of known anelloviruses, circoviruses, and parvoviruses were obtained, as well as putative novel species. We demonstrate that the metagenomics approach applied in this work was effective for identification of known and putative new viruses in faeces samples from Brazilian Cerrado fauna.

Isolation and characterization of duck adenovirus 3 circulating in China

Recently, infectious disease outbreaks characterized by swelling and hemorrhagic liver and kidneys occurred in Muscovy ducklings in China. Four viruses were isolated and identified as adenoviruses by transmission electron microscopy (TEM) and polymerase chain reaction (PCR). Sequence analysis identified the new isolates as duck adenovirus 3 (DAdV-3), species Duck aviadenovirus B. The pathogenicity of the new isolate DAdV-3 FJGT01 was investigated using challenge experiments. The gross lesions in the animal experiment were similar to the clinical lesions observed in the diseased ducks. TEM examination of liver sample showed that virions accumulated and arranged in crystal lattice formations in the nuclei of hepatocytes. The present study provides new information about the epidemiology and characteristics of duck adenovirus associated with Muscovy ducklings.

MOLECULAR IDENTIFICATION OF AVIAN VIRUSES IN NEOTROPIC CORMORANTS ( PHALACROCORAX BRASILIANUS) IN CHILE

We identified two RNA (paramyxovirus and coronavirus) and two DNA (adenovirus and herpesvirus) viruses in a common aquatic bird, the Neotropic Cormorant ( Phalacrocorax brasilianus), and determined their phylogenetic relationships to other global circulating variants. We analyzed 104 cloacal swabs from individuals collected at locations in Central Chile. Sequences were obtained from amplicons using consensus primers targeting conserved genes of the virus families Paramyxoviridae, Coronaviridae, Adenoviridae, and Herpesviridae. A total of 20.2% of the samples was positive for coronavirus, 8.7% for adenovirus, and 3.8% for herpesvirus. No paramyxoviruses were detected. All coronaviruses were identified as viruses of the Gammacoronavirus genus, closely related to the infectious bronchitis virus clade (bootstrap clade support=75%). All adenovirus samples were identified as Aviadenovirus, related to a gull and falcon adenovirus (Bayesian posterior probability=0.86). The herpesviruses identified were related to the infectious laryngotracheitis virus ( Gallid herpesvirus 1) of the genus Iltovirus (bootstrap clade support=99%). We provide information about the diversity of viruses circulating among apparently healthy Neotropic Cormorants.

Molecular characterization of fowl aviadenoviruses species D and E associated with inclusion body hepatitis in chickens and falcons indicates possible cross-species transmission

During the period from 2015 to 2017, frequent outbreaks of inclusion body hepatitis (IBH) were observed in broiler chickens and falcons in Saudi Arabia. Fifty samples were collected from both species. The histopathological examination and polymerase chain reaction confirmed the IBH infection in eight samples (five samples from chickens and three samples from falcons). The genomic sequence and phylogenetic analysis based on nucleotide and amino acid sequences of Saudi strains, reference fowl aviadenoviruses (FAdVs) and field viruses available in Genbank revealed that all investigated FAdVs clustered into FAdV-2 (species D) and FAdV-6 (species E). The host-dependent characterization revealed that falcon origin strains showed low identity (∼35%) with falcon adenoviruses isolated from USA, which clustered into a separate group. The identification of FAdV-D and FAdV-E in diseased falcons and chickens indicates cross-species transmission although falcons and chickens are phylogenetically different. The control of IBH infection in falcons and chickens should be based on the separation of carriers and susceptible chickens as well as falcons to prevent cross-species contact. Vaccination is an important method for prevention of IBH. The characterization of newly emerging FAdV strains provides valuable information for the development of an efficacious control strategy based on the molecular structure of current circulating FAdV strains in different species of birds.

Different Dynamic Distribution in Chickens and Ducks of the Hypervirulent, Novel Genotype Fowl Adenovirus Serotype 4 Recently Emerged in China

A hypervirulent fowl adenovirus serotype 4 (FAdV-4) has caused hepatitis-hydropericardium syndrome (HHS) with mortalities that range from 30 to 80% in outbreaks across China since 2015. The FAdV-4 strain was characterized as a novel genotype based on the specific genome characteristics. However, our understanding of the dynamic distribution, tissue tropism, and pathogenesis of the novel FAdV-4 is incomplete. In this study, a new, sensitive and FAdV-4-specific real-time PCR was developed and applied to detect the dynamic distribution of the duck origin, novel FAdV-4 strain HLJDAd15 in experimentally infected special-pathogen free (SPF) chickens and ducks. Notably, the pathogenicity and replication pattern of HLJDAd15 were completely different between chickens and ducks. Severe hydropericardium and 10% mortality were induced in chickens, whereas no clinical signs were observed in any duck. The virus replicated was detected throughout the study in both chickens and ducks. However, only one replication peak with a high virus concentration appeared in chickens at 5 days post infection (dpi), whereas two peaks with relatively low virus titres appeared in ducks at 7 and 21 dpi. Thus, ducks could be a natural reservoir of the novel FAdV-4 absent of clinical signs, and a new transmission route from ducks shedding FAdV-4 continually to chickens was revealed, which might aggravate the outbreak of HHS in chickens. This study provides the first accurate quantitative data for the replication kinetics of the novel FAdV-4 in different hosts. The different pathogenicity, dynamic distribution and replication pattern in chickens and ducks provide a foundation for further clarification of the pathogenesis of the novel FAdV-4.

Faecal virome of healthy chickens reveals a large diversity of the eukaryote viral community, including novel circular ssDNA viruses

This study is focused on the identification of the faecal virome of healthy chickens raised in high-density, export-driven poultry farms in Brazil. Following high-throughput sequencing, a total of 7743 de novo-assembled contigs were constructed and compared with known nucleotide/amino acid sequences from the GenBank database. Analyses with blastx revealed that 279 contigs (4 %) were related to sequences of eukaryotic viruses. Viral genome sequences (total or partial) indicative of members of recognized viral families, including Adenoviridae, Caliciviridae, Circoviridae, Parvoviridae, Picobirnaviridae, Picornaviridae and Reoviridae, were identified, some of those representing novel genotypes. In addition, a range of circular replication-associated protein encoding DNA viruses were also identified. The characterization of the faecal virome of healthy chickens described here not only provides a description of the viruses encountered in such niche but should also represent a baseline for future studies comparing viral populations in healthy and diseased chicken flocks. Moreover, it may also be relevant for human health, since chickens represent a significant proportion of the animal protein consumed worldwide.

Veterinary Aspects of Bird of Prey Reproduction

Captive breeding has contributed to successful restoration of many species of birds of prey. Avicultural techniques pioneered by raptor breeders include double clutching, direct fostering, cross-fostering, hatch and switch, hacking, imprinting male and female falcons for semen collection, and artificial insemination techniques. However, reproductive failure occurs related to management problems, including hygiene measures, food quality issues, breeding flock structure, or individual health issues of breeding birds. These may result in non-egg laying females, low-quality eggs, or infertile eggs caused by male infertility. Veterinary care of breeding collections is extremely important. This article provides an overview of veterinary involvement in raptor breeding projects.

Molecular Assays for Detection of Falcon Adenovirus

Falcon adenovirus is a newly recognized member of the family Aviadenoviridae and includes 2 closely related strains that are pathogenic to several species of falcons. Peregrine falcons appear to be one of the primary reservoirs, but recent outbreaks suggest that other carrier species probably exist. To allow screening of captive birds for virus shedding and investigations of disease outbreaks, conventional and realtime, quantitative polymerase chain reaction (PCR) assays and an in situ hybridization technique were developed. The diagnostic protocols were used on tissue and fecal samples from 7 species or subspecies of falcons infected with adenovirus as well as adenoviruses from other birds and mammals. The assays were specific for falcon adenovirus and detected both strains of virus in fecal samples from living animals or frozen and formalin-fixed, paraffinized tissues. Together with established serologic tests for falcon adenovirus, these molecular assays are valuable tools for management and conservation of falcons in captivity and the wild.

Identification of a novel aviadenovirus, designated pigeon adenovirus 2 in domestic pigeons (Columba livia)

The young pigeon disease syndrome (YPDS) affects mainly young pigeons of less than one year of age and leads to crop stasis, vomitus, diarrhea, anorexia and occasionally death. This disease is internationally a major health problem because of its seasonal appearance during competitions such as homing pigeon races or exhibitions of ornamental birds. While the etiology of YPDS is still unclear, adenoviruses are frequently discussed as potential causative agents. Electron microscopy of feces from a YPDS outbreak revealed massive shedding of adenovirus-like particles. Whole genome sequencing of this sample identified a novel adenovirus tentatively named pigeon adenovirus 2 (PiAdV-2). Phylogenetic and comparative genome analysis suggest PiAdV-2 to belong to a new species within the genus Aviadenovirus, for which we propose the name Pigeon aviadenovirus B. The PiAdV-2 genome shares 54.9% nucleotide sequence identity with pigeon adenovirus 1 (PiAdV-1). In a screening of further YPDS-affected flocks two variants of PiAdV-2 (variant A and B) were detected which shared 97.6% nucleotide identity of partial polymerase sequences, but only 79.7% nucleotide identity of partial hexon sequences. The distribution of both PiAdV-2 variants was further investigated in fecal samples collected between 2008 and 2015 from healthy or YPDS-affected racing pigeons of different lofts. Independent of their health status, approximately 20% of young and 13% of adult pigeon flocks harbored PiAdV-2 variants. Birds were free of PiAdV-1 or other aviadenoviruses as determined by PCRs targeting the aviadenovirus polymerase or the PiAdV-1 fiber gene, respectively. In conclusion, there is no indication of a correlation between YPDS outbreaks and the presence of PiAdV-2 or other aviadenoviruses, arguing against an causative role in this disease complex.

Falcon Adenovirus Infection in Breeding Taita Falcons (Falco Fasciinucha)

Four female and 3 male Taita falcons ( Falco fasciinucha) out of a breeding colony of 14 Taita falcons (7 pairs) died during the breeding season after showing lethargy and anorexia for 1 to 2 days. All animals were submitted for necropsy. Gross lesions in the female falcons were characterized by anemia secondary to marked hemorrhage into the ovary and oviduct, serofibrinous effusion into the cardioabdominal cavity and serosal petechiae. In addition, marked necrotizing splenitis and pulmonary hemorrhage were present. Histologically, the female falcons had mild necrotizing hepatitis with numerous intranuclear inclusion bodies and necrotizing splenitis with rare inclusion bodies. There were no gross lesions in the male falcons, and the histological lesions were characterized by urate deposition and rare intranuclear inclusion bodies in the renal tubular epithelial cells. Adenoviral particles were found by electron microscopy in the cloacal contents of the female Taita falcons but not in the male falcons. DNA in situ hybridization revealed widespread aviadenoviral nucleic acid within the nuclei of hepatocytes, renal tubular epithelial cells, and adrenal cells in the female falcons but no aviadenoviral nucleic acid in 1 male falcon and only a low quantity of adenoviral nucleic acid in the liver and kidney of another male Taita falcon. PCR amplified aviadenoviral DNA in the liver and intestine of all Taita falcons. The amplicons were sequenced, and the virus was identified as falcon adenovirus. The deaths of the female and male birds were attributed to the aviadenovirus infection.

Molecular characterization, phylogeny analysis and pathogenicity of a Muscovy duck adenovirus strain isolated in China in 2014

This study aimed to characterize a novel adenovirus (AdV) isolated from diseased Muscovy ducks in China. After the AdV was successfully propagated in duck embryo fibroblasts, the morphological and physicochemical properties of the virions were studied by electron microscopy and different tests. The results of the analyses were in conformity with AdV properties. The full genome sequence was determined and analyzed. The new isolate (named CH-GD-12-2014) shared over 91% sequence identity with duck AdV-2 representing the species Duck aviadenovirus B. The most important distinguishing feature between the two DAdV strains was the presence of a second fiber gene in the Chinese isolate. Phylogeny reconstruction confirmed the affiliation of the virus with goose and duck AdVs in the genus Aviadenovirus. Experimental infection resulted in embryo death, and intramuscular inoculation provoked morbidity and mortality among ducks and chickens.

Seroepidemiologic Survey of Potential Pathogens in Obligate and Facultative Scavenging Avian Species in California

Throughout the world, populations of scavenger birds are declining rapidly with some populations already on the brink of extinction. Much of the current research into the factors contributing to these declines has focused on exposure to drug residues, lead, and other toxins. Despite increased monitoring of these declining populations, little is known about infectious diseases affecting scavenger bird species. To assess potential infectious disease risks to both obligate and facultative scavenger bird species, we performed a serosurvey for eleven potential pathogens in three species of scavenging birds in California: the California condor (Gymnogyps californianus), turkey vulture (Cathartes aura) and golden eagle (Aquila chrysaetos). California condors were seropositive for avian adenovirus, infectious bronchitis virus, Mycoplasma gallisepticum, avian paramyxovirus-2, West Nile virus (WNV) and Toxoplasma gondii. Golden eagles were seropositive for avian adenovirus, Chlamydophila psittaci and Toxoplasma gondii, and turkey vultures were seropositive for avian adenovirus, Chlamydophila psittaci, avian paramyxovirus-1, Toxoplasma gondii and WNV. Risk factor analyses indicated that rearing site and original release location were significantly associated with a positive serologic titer to WNV among free-flying condors. This study provides preliminary baseline data on infectious disease exposure in these populations for aiding in early disease detection and provides potentially critical information for conservation of the endangered California condor as it continues to expand its range and encounter new infectious disease threats.

Raptor gastroenterology

Free-living raptors are frequently presented to wildlife rehabilitation centers. Conditions affecting the gastrointestinal tract can be the primary reason for presentation. The gastrointestinal tract can also be affected secondary to debilitation from other injuries or from the stress of the rehabilitation process. A thorough understanding of the anatomy, physiology, and natural history of these species is crucial to successful treatment and rehabilitation. This article addresses raptor gastroenterology with an emphasis on conditions affecting free-living birds.

A novel adenovirus in Chinstrap penguins (Pygoscelis antarctica) in Antarctica

Adenoviruses (family Adenoviridae) infect various organ systems and cause diseases in a wide range of host species. In this study, we examined multiple tissues from Chinstrap penguins (Pygoscelis antarctica), collected in Antarctica during 2009 and 2010, for the presence of novel adenoviruses by PCR. Analysis of a 855-bp region of the hexon gene of a newly identified adenovirus, designated Chinstrap penguin adenovirus 1 (CSPAdV-1), showed nucleotide (amino acid) sequence identity of 71.8% (65.5%) with South Polar skua 1 (SPSAdV-1), 71% (70%) with raptor adenovirus 1 (RAdV-1), 71.4% (67.6%) with turkey adenovirus 3 (TAdV-3) and 61% (61.6%) with frog adenovirus 1 (FrAdV-1). Based on the genetic and phylogenetic analyses, CSPAdV-1 was classified as a member of the genus, Siadenovirus. Virus isolation attempts from kidney homogenates in the MDTC-RP19 (ATCC® CRL-8135™) cell line were unsuccessful. In conclusion, this study provides the first evidence of new adenovirus species in Antarctic penguins.

Whole-genome sequences of two turkey adenovirus types reveal the existence of two unknown lineages that merit the establishment of novel species within the genus Aviadenovirus

There are eight species established for aviadenoviruses: Fowl adenovirus A–E, Goose adenovirus A, Falcon adenovirus A and Turkey adenovirus B. The aim of this study was to sequence and analyse the complete genomes of turkey adenovirus 4 (TAdV-4) and TAdV-5 (strain 1277BT) in addition to almost two-thirds of the genome of another TAdV-5 strain (strain D1648). By applying next-generation sequencing, the full genomes were found to be 42 940 and 43 686 bp and the G+C content was 48.5 and 51.6 mol% for TAdV-4 and TAdV-5, respectively. One fiber gene was identified in TAdV-4, whereas two fiber genes were found in TAdV-5. The genome organization of TAdV-4 resembled that of fowl adenovirus 5 (FAdV-5), but it had ORF1C near the left end of the genome. TAdV-4 also had five 123 bp tandem repeats followed by five 33 bp tandem repeats, but they occurred before and not after ORF8, as in several fowl adenoviruses. The genome organization of TAdV-5 was almost the same as that of FAdV-1 but with a possible difference in the splicing pattern of ORF11 and ORF26. Phylogenetic analyses and G+C content showed differences that seem to merit the establishment of two new species within the genus Aviadenovirus: Turkey adenovirus C (for TAdV-4) and Turkey adenovirus D (for TAdV-5). Our analyses suggest a common evolutionary origin of TAdV-5 and FAdV-1.

Genome sequence of a waterfowl aviadenovirus, goose adenovirus 4

We present, to our knowledge, the first complete genome sequence of a waterfowl aviadenovirus, goose adenovirus (GoAdV) strain P29, and an analysis of its genetic content in comparison with five published aviadenovirus genome sequences. Of the 35 genes predicted to encode functional proteins, the central region of the genome contains 19 (IVa2 to fiber-2) that were inherited from the ancestor of all known adenoviruses. Of the remaining genes, nine have orthologues only in aviadenoviruses and seven lack orthologues in any adenovirus. We also obtained limited sequence data for a pathogenic GoAdV strain D1036/08. Phylogenetic analyses placed the two GoAdV strains monophyletically in the genus Aviadenovirus. We propose designating strains P29 and D1036/08 as GoAdV-4 and GoAdV-5, respectively.

Deep RNA sequencing reveals complex transcriptional landscape of a bat adenovirus

Bat adenoviruses are a group of recently identified adenoviruses (AdVs) which are highly prevalent in bats yet share low similarity to known AdVs from other species. In this study, deep RNA sequencing was used to analyze the transcriptome at five time points following the infection of a bat AdV in a kidney cell line derived from a myotis bat species. Evidence of AdV replication was observed with the proportion of viral RNAs ranging from 0.01% at 6 h to 1.3% at 18 h. Further analysis of viral temporal gene expression revealed three replication stages, the early-stage genes encoding mainly host interaction proteins, the intermediate-stage genes for the DNA replication and assembly proteins, and the late-stage genes for most structural proteins. Several bat AdV genes were expressed at stages that differed from those of their counterpart genes previously reported for human AdV type 2. In addition, single-base resolution splice sites of several genes and promoter regions of all 30 viral genes were fully determined. Simultaneously, the temporal cellular gene expression profiles were identified. The most overrepresented functional categories of the differentially expressed genes were related to cellular immune response, transcription, translation, and DNA replication and repair. Taken together, the deep RNA sequencing provided a global, transcriptional profile of the novel bat AdV and the virus-host interactions which will be useful for the understanding and investigation of AdV replication, pathogenesis, and specific virus-bat interactions in future research.

Full genome analysis of a novel adenovirus from the South Polar skua (Catharacta maccormicki) in Antarctica

Adenoviruses have been identified in humans and a wide range of vertebrate animals, but not previously from the polar region. Here, we report the entire 26,340-bp genome of a novel adenovirus, detected by PCR, in tissues of six of nine South Polar skuas (Catharacta maccormicki), collected in Lake King Sejong, King George Island, Antarctica, from 2007 to 2009. The DNA polymerase, penton base, hexon and fiber genes of the South Polar skua adenovirus (SPSAdV) exhibited 68.3%, 75.4%, 74.9% and 48.0% nucleotide sequence similarity with their counterparts in turkey hemorrhagic enteritis virus. Phylogenetic analysis based on the entire genome revealed that SPSAdV belonged to the genus Siadenovirus, family Adenoviridae. This is the first evidence of a novel adenovirus, SPSAdV, from a large polar seabird (family Stercorariidae) in Antarctica.

Preparation and evaluation of chicken embryo-adapted fowl adenovirus serotype 4 vaccine in broiler chickens

The current study was planned to develop an efficient vaccine against hydropericardium syndrome virus (HSV). Currently, formalin-inactivated liver organ vaccines failed to protect the Pakistan broiler industry from this destructive disease of economic importance. A field isolate of the pathogenic hydropericardium syndrome virus was adapted to chicken embryos after four blind passages. The chicken embryo-adapted virus was further serially passaged (12 times) to get complete attenuation. Groups of broiler chickens free from maternal antibodies against HSV at the age of 14 days were immunized either with 16th passage attenuated HSV vaccine or commercially formalized liver organ vaccine. The antibody response, measured by enzyme-linked immunosorbent assay was significantly higher (P < 0.05) in the group immunized with the 16th passage attenuated HSV vaccine compared to the group immunized with liver organ vaccine at 7, 14, and 21 days post-immunization. At 24 days of age, the broiler chickens in each group were challenged with 10(3.83) embryo infectious dose(50) of pathogenic HSV and were observed for 7 days post-challenge. Vaccination with the 16th passage attenuated HSV gave 94.73% protection as validated on the basis of clinical signs (5.26%), gross lesions in the liver and heart (5.26%), histopathological lesions in the liver (1.5 ± 0.20), and mortality (5.26%). The birds inoculated with liver organ vaccine showed significantly low (p < 0.05; 55%) protection estimated on the basis of clinical signs (40%), gross lesions in the liver and heart (45%), histopathological lesions in the liver (2.7 ± 0.72), and mortality (35%). Birds in the unvaccinated control group showed high morbidity (84%), mortality (70%), gross (85%), and histopathological lesions (3.79 ± 0.14) with only 10% protection. In conclusion, this newly developed HSV vaccine proved to be immunogenic and has potential for controlling HSV infections in chickens.

New adenovirus in bats, Germany

We tested 55 deceased vespertilionid bats of 12 species from southern Germany for virus infections. A new adenovirus was isolated from tissue samples of 2 Pipistrellus pipistrellus bats, which represents the only chiropteran virus isolate found in Europe besides lyssavirus (rabies virus). Evidence was found for adenovirus transmission between bats.

Host range, prevalence, and genetic diversity of adenoviruses in bats

Bats are the second largest group of mammals on earth and act as reservoirs of many emerging viruses. In this study, a novel bat adenovirus (AdV) (BtAdV-TJM) was isolated from bat fecal samples by using a bat primary kidney cell line. Infection studies indicated that most animal and human cell lines are susceptible to BtAdV-TJM, suggesting a possible wide host range. Genome analysis revealed 30 putative genes encoding proteins homologous to their counterparts in most known AdVs. Phylogenetic analysis placed BtAdV-TJM within the genus Mastadenovirus, most closely related to tree shrew and canine AdVs. PCR analysis of 350 bat fecal samples, collected from 19 species in five Chinese provinces during 2007 and 2008, indicated that 28 (or 8%) samples were positive for AdVs. The samples were from five bat species, Hipposideros armiger, Myotis horsfieldii, M. ricketti, Myotis spp., and Scotophilus kuhlii. The prevalence ranged from 6.25% (H. armiger in 2007) to 40% (M. ricketti in 2007). Comparison studies based on available partial sequences of the pol gene demonstrated a great genetic diversity among bat AdVs infecting different bat species as well as those infecting the same bat species. This is the first report of a genetically diverse group of DNA viruses in bats. Our results support the notion, derived from previous studies based on RNA viruses (especially coronaviruses and astroviruses), that bats seem to have the unusual ability to harbor a large number of genetically diverse viruses within a geographic location and/or within a taxonomic group.

Confirmation of a novel siadenovirus species detected in raptors: partial sequence and phylogenetic analysis

Partial genome characterisation of a novel adenovirus, found recently in organ samples of multiple species of dead birds of prey, was carried out by sequence analysis of PCR-amplified DNA fragments. The virus, named as raptor adenovirus 1 (RAdV-1), has originally been detected by a nested PCR method with consensus primers targeting the adenoviral DNA polymerase gene. Phylogenetic analysis with the deduced amino acid sequence of the small PCR product has implied a new siadenovirus type present in the samples. Since virus isolation attempts remained unsuccessful, further characterisation of this putative novel siadenovirus was carried out with the use of PCR on the infected organ samples. The DNA sequence of the central genome part of RAdV-1, encompassing nine full (pTP, 52K, pIIIa, III, pVII, pX, pVI, hexon, protease) and two partial (DNA polymerase and DBP) genes and exceeding 12 kb pairs in size, was determined. Phylogenetic tree reconstructions, based on several genes, unambiguously confirmed the preliminary classification of RAdV-1 as a new species within the genus Siadenovirus. Further study of RAdV-1 is of interest since it represents a rare adenovirus genus of yet undetermined host origin.

Genotyping of Canadian isolates of fowl adenoviruses

Five hundred and seventy-three clinical submissions with fowl adenovirus (FAdV) involvement were examined to investigate the association of different types of FAdV with clinical problems related to FAdV infection. Samples were received from 2000 to 2006 and originated from seven Canadian provinces. Four hundred and eighty-seven submissions were inclusion body hepatitis (IBH) related, while 86 were not IBH related. Viruses isolated from 287 samples were further analysed by hexon gene loop 1 sequencing. Twenty-seven genotyped FAdVs were from Alberta, 20 from British Columbia, 16 from Manitoba, one from Nova Scotia, 82 from Ontario, 64 from Quebec and 77 from Saskatchewan. Two hundred and forty-six analysed FAdVs were from IBH cases, confirmed by liver histopathology, by FAdV isolation from the liver, or both. Based on hexon gene loop 1 sequencing analysis, FAdVs associated with IBH outbreaks were genetically related to FAdV02 (nine isolates, 99.4%), FAdV08a (100 isolates, 99.4% to 100%) and FAdV11 (98 isolates, 99.4% to 100%). Thirty-nine viruses were 93.7% to 94.3% identical to FAdV07 strain x11a, but the genetic and immunogenic properties of this strain require further investigation. In IBH cases, the co-infection rates for infectious bursal disease virus, infectious bronchitis virus, reoviruses and Newcastle disease virus were 3.47%, 1.04%, 6.25% and 0.69%, respectively. Forty-one genotyped FAdVs were from "non-IBH" cases. Viruses isolated from non-IBH cases consisted of 22 FAdV01, 15 FAdV11, two FAdV08a and one each of FAdV02 and FAdV04 viruses. Co-infection rates in non-IBH submissions were 50.00% for infectious bursal disease virus, 40.70% for infectious bronchitis virus, 27.91% for reoviruses and 1.16% for Newcastle disease virus.

Falcon adenovirus in an American kestrel (Falco sparverius)

A fatal adenovirus infection is described in a wild-caught American kestrel (Falco sparverius). Predominate lesions were a moderate to severe hepatitis with diffuse single-cell necrosis of hepatocytes and a splenitis characterized by necrosis of cells surrounding the sheathed arteries. Pan-nuclear eosinophilic to magenta inclusion bodies were abundant within hepatocytes. Polymerase chain reaction was used to amplify a portion of the hexon gene from DNA extracted from the bird's liver and spleen. Sequence analysis showed that the adenovirus infecting this kestrel was the falcon adenovirus with a sequence homology of 99.5% to the isolate from the Northern aplomado falcon (Falco femoralis) variant and 98.6% homology to isolates from the taita (Falco fasciinucha) and orange-breasted falcons (Falco deiroleucus). This report expands the range of species of falcons that are susceptible to falcon adenovirus infection and disease. Given that this kestrel was recently wild caught and housed in isolation with other wild-caught kestrels, it is likely that the falcon adenovirus is present in wild populations of American kestrels.

Isolation and epidemiology of falcon adenovirus

An adenovirus was detected by electron microscopy in tissues from falcons that died during an outbreak of inclusion body hepatitis and enteritis that affected neonatal Northern aplomado (Falco femoralis septentrionalis) and peregrine (Falco peregrinus anatum) falcons. Molecular characterization has identified the falcon virus as a new member of the aviadenovirus group (M. Schrenzel, J. L. Oaks, D. Rotstein, G. Maalouf, E. Snook, C. Sandfort, and B. Rideout, J. Clin. Microbiol. 43:3402-3413, 2005). In this study, the virus was successfully isolated and propagated in peregrine falcon embryo fibroblasts, in which it caused visible and reproducible cytopathology. Testing for serum neutralizing antibodies found that infection with this virus was limited almost exclusively to falcons. Serology also found that wild and captive peregrine falcons had high seropositivity rates of 80% and 100%, respectively, although clinical disease was rarely reported in this species. These data implicate peregrine falcons as the natural host and primary reservoir for the virus. Other species of North American falcons, including aplomado falcons, had lower seropositivity rates of 43 to 57%. Falcon species of tropical and/or island origin were uniformly seronegative, although deaths among adults of these species have been described, suggesting they are highly susceptible. Chickens and quail were uniformly seronegative and not susceptible to infection, indicating that fowl were not the source of infection. Based on the information from this study, the primary control of falcon adenovirus infections should be based on segregation of carrier and susceptible falcon species.