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.

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.

Electron microscopic identification of viruses associated with poult enteritis in turkeys grown in California 1993-2003.

Poult enteritis (PE) is one of the most common diseases seen in young turkey flocks. Since 1993, more than 1800 cases of suspected PE have been submitted for examination by negative stain electron microscopy; this has involved more than 2400 individual results, because in many cases more than one virus was identified; at least 1500 individual results were positive for viruses. Viruses have been identified in poults as young as 3 days and up to 9 wk of age. The most commonly found viruses are rotavirus-like viruses and small round viruses ranging from 15 nm to 30 nm, either alone or in combination. Reovirus, birnavirus, and adenovirus have also been detected. There has been no evidence to suggest the presence of coronaviruses. This report summarizes our findings.

Adenovirus group II-like infection in chukar partridges (Alectoris chukar).

Seven live 5-to-6-wk-old chukar partridges (Alectoris chukar) were examined because of increased lacrimation, swollen eyelids, and increased mortality. Gross lesions consisted of mildly enlarged and mottled white spleens, swollen eyelids with external scab formation, and watery intestinal contents. Microscopically, there were increased numbers of mononuclear phagocytic system cells in the spleen, some of which contained faintly staining basophilic intranuclear inclusion bodies, blepharoconjunctivitis, enteritis associated with coccidia and crop mycosis. Transmission electron microscopy of the spleen revealed icosahedral virus particles 65 to 75 nm in diameter, consistent with the morphology of adenovirus. Three out of seven chukars were positive for hemorrhagic enteritis virus by serology.

Purification and characterization of the aetiological agent of hydropericardium hepatitis syndrome from infected liver tissues of broiler chickens.

Hydropericardium hepatitis syndrome in broiler chickens is an acute, infectious disease characterized by high mortality, excess pericardial fluid and multifocal hepatic necrosis. The aetiological agent was purified to homogeneity from infected liver tissues from field outbreaks. Electron-microscopic and serological confirmation of the virus were undertaken and the disease was reproduced experimentally in broiler chicks. The results indicated that an adenovirus, fowl adenovirus serotype 4, was alone responsible for the disease in the materials studied.

[Adenovirus KR95, isolated from chickens during an outbreak of hydropericarditis, is the pathogen of this disease]. / Adenovirus KR95, vydelennyi ot tsypliat vo vremia vspyshki gidroperikardita, iavliaetsiia vozbuditelem étogo zabolevaniia.

Virus agent KR95 was isolated from the liver of dieoff chickens during an outbreak of hydropericarditis syndrome at a poultry farm in Russia. Electron microscopic examination of the virus morphology, comparative restriction cleavage map construction, DNA-DNA hybridization, and analysis of structural proteins from purified and disrupted virions showed that the agent is to be classified as type 1 avian adenovirus.

[Adenovirus infections in psittacines]. / Adenovirusinfektion bei Psittaziden.

Diagnostic investigations were carried out in a fatal disease of several African Grey Parrots (Psittacus erithacus) and Cape Parrots (Poicephalus robustus) in a large breeding plant. Electron microscopically examination of liver and intestine, the organs with the most prominent pathomorphological changes, regularly revealed adenoviruses. Necrotizing hepatitis and catarrhal to haemorrhagic enteritis dominated on histopathological examination. Numerous basophilic intranuclear inclusion bodies in hepatocytes and enterocytes and their ultrastructural characteristics underline the etiological role of the detected adenoviruses. Adenoviruses were isolated from livers of three different birds and once from the intestine. Serologically the isolates were classified as fowl adenovirus serotype 4 (FAV4). Restriction enzyme analysis of two isolates showed the identity with the FAV4 reference strain KR5.

DNA in situ hybridization for the rapid diagnosis of massive necrotizing avian adenovirus hepatitis and pancreatitis in chicks.

The present study describes the use of DNA in situ hybridization for the rapid diagnosis of massive necrotizing adenovirus hepatitis and pancreatitis in broiler chicks. A light microscope and DNA probes were used to identify avian adenovirus in replicate sections of formalin-fixed paraffin-embedded liver and pancreas from field and experimental chicks. Avian adenovirus infection was confirmed by transmission electron microscopy and virus isolation.

The avian adenovirus penton: two fibres and one base.

The penton capsomer of mammalian adenoviruses consists of a trimeric, long and thin fibre inserted into a pentameric base. The avian adenoviruses possess a penton which presents another symmetry mismatch: each pentameric base is associated with two fibres. Here we have studied the morphology of the penton of CELO virus, an avian adenovirus, and we have determined the sequence of both fibres, one long and one short. The short fibre is probably associated with the base in the same way as the mammalian viral fibres and we will discuss how the long fibre could be attached. The shafts of all known adenovirus fibres consist of a series of 15-residue repeats. The avian virus fibres show a more complicated and less regular shaft repeat structure with single, double and triple repeats. The sequences of the receptor binding (head) domains of both fibres are very different from all other known fibre head domains and very different from each other, suggesting that the two fibres might bind to different receptors. The genome organization of the sequenced region is rather different from that in human adenoviruses. In particular, a region homologous to the human virus E3 region was not found at the position where it normally occurs in the human virus genome.

Hemorrhagic enteritis by adenovirus-like particles in turkeys: a possible pathogenic mechanism.

This paper describes an outbreak of hemorrhagic enteritis due to adenovirus in turkeys in Spain. Diagnosis of the disease was confirmed by histopathological examination and the observation of adenovirus in spleen mononuclear cells and intestinal infiltrate. Evidence was also found of intravascular coagulation, which may give rise to the bleeding considered characteristic of this disease.

Inclusion body hepatitis in Gambel's quail (Callipepla gambelii).

An acute necrotizing hepatitis in 1- to 3-wk-old Gambel's quail (Callipepla gambelii) caused by an adenovirus is described. The infection caused high mortality in captive raised, orphan chicks at two wildlife rehabilitation facilities in Arizona (USA). Gross lesions varied from pale livers to multiple, pinpoint, white foci scattered throughout the livers. Microscopically, scattered foci of hepatocellular necrosis were present. Intact hepatocytes at teh periphery of necrotic foci had eosinophilic and basophilic intranuclear inclusion bodies.

Liquid crystalline DNA in fowl adenovirus.

Fowl adenovirus particles were studied using negative stain electron microscopy. Upon preparation, some particles collapsed and showed their internal structure. The DNA could be observed as thin parallel lines with a spacing of 25 A, very similar to images of the liquid crystalline DNA in bacteriophage heads and in herpes virus.

Inclusion bodies containing adenovirus-like particles in the intestine of a psittacine bird affected by inclusion body hepatitis.

This paper reports a case of inclusion body hepatitis with intranuclear inclusion bodies in the liver and the intestine of a Yellow-naped Amazon parrot (Amazona ochrocephala). Structurally, basophilic intranuclear inclusion bodies were found in hepatic cells and enterocytes. Ultrastructurally, icosahedral adenovirus-like particles, 60-75 nm in diameter, were found in the same cells.

Relationship between age of flock seroconversion to hemorrhagic enteritis virus and appearance of adenoviral inclusions in the spleen and renal tubule epithelia of turkeys.

A retrospective study was conducted to evaluate the temporal relationship between flock seroconversion to hemorrhagic enteritis virus (HEV) and the appearance of adenoviral inclusions in the spleen and renal tubular epithelium. The study was conducted on samples of turkey poults submitted to the Fresno Branch of the California Veterinary Diagnostic Laboratory System during May to December 1988. The study included 78 submissions (four to eight poults per submission) of ages ranging from 6 to 15 weeks. Sera were tested for antibodies to HEV using the agar gel immunodiffusion test. Spleen and kidney samples were examined by light microscopy for the presence of inclusions in the mononuclear phagocytes of the spleen or in the renal tubular epithelium of the kidney. Logistic regression statistical analysis was used to evaluate the association between the age of the bird and the likelihood of the presence of inclusions in the spleen and kidney, as well as the likelihood of seroconversion to HEV. A significant association (P less than 0.05) was found between the presence of splenic inclusion bodies and the age of the bird. The probability of splenic inclusions was higher in younger birds (6 weeks of age), and decreased as the birds became older, approaching zero at 11 weeks of age. The kidney inclusions were significantly associated with age. The probability of detecting the inclusions increased with age, reached a maximum at 10 weeks, and then declined, approaching zero by 14 weeks. However, the probability of seroconversion to HEV increased significantly with age up to 10 weeks and then remained positive throughout the remainder of the study period.

Characterization of the structural proteins of hemorrhagic enteritis virus.

The structural proteins of hemorrhagic enteritis (HEV), a turkey adenovirus, were analyzed by polyacrylamide gel electrophoresis (PAGE) and Western blotting using polyspecific, monospecific and monoclonal antibodies for detection. In purified HEV preparations, eleven polypeptides with apparent molecular weights ranging from 96,000 to 9,500 (96k to 9.5k), were specifically recognized by convalescent turkey serum. Six of these polypeptides were further characterized by PAGE, Western blotting, ELISA, sucrose gradient centrifugation and electron microscopy. The 96k polypeptide was identified as the hexon polypeptide which is a monomer of the major outer capsid or hexon protein. The 51/52k and 29k polypeptides, identified as the penton base and fiber polypeptides respectively, were the components of the vertex or penton protein. The 57k polypeptide was identified as a homologue of the human adenovirus type 2 (Ad 2) IIIa protein with which it shares a common epitope. Two core proteins with molecular weights of 12.5 and 9.5k were present in purified HEV nucleoprotein cores. The proteins of two HEV isolates, one apathogenic (HEV-A) and one virulent (HEV-V), resembled each other in most respects. However, differences between HEV-A and HEV-V were found in electrophoretic migration of the penton base protein both under native and denatured conditions, and in the electrophoretic migration of the 43/44k polypeptide. Moreover, homologous antiserum against the fiber protein reacted stronger than heterologous antiserum in an ELISA. Single fibers were detected by electron microscopy attached to the penton base proteins of HEV virions and in isolated pentons. The feature of having single fibers is shared with the mammalian adenoviruses and the avian egg drop syndrome 1976 virus (EDS 76 V), but not with the fowl adenoviruses which have double fibers attached to their penton base proteins.

Respiratory adenovirus-like infection in a rose-ringed parakeet (Psittacula krameri).

Intranuclear inclusions were observed under light microscopy in the bronchial epithelial cells of a recently purchased female rose-ringed parakeet that died of chlamydiosis. Transmission electron microscopy revealed the presence of numerous particles of adenovirus morphology. A latent adenovirus infection may have become more severe following chlamydiosis and the stress of handling.

Identification and characterization of viral polypeptides from type-II avian adenoviruses.

The polypeptides of serologically related viruses of hemorrhagic enteritis (HE) in turkeys, marble spleen disease (MSD) in pheasants, and splenomegaly in chickens (SMC) were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and analyzed by protein immunoblotting with polyclonal antibodies to HE virus (HEV). The viral polypeptides II, III, IV, V, VI, and VII were detected on SDS-PAGE with the size range from 18 to 97 kDa in HEV. Viral polypeptides II, III, V, VI, and VII were detected in MSD virus and virus of SMC. Protein immunoblotting of viral proteins with anti-HEV serum revealed antigenic differences between the 3 viruses of avian adenovirus type-II examined. The differences were that the polypeptides II, III, IV, V, VI, and VII were identified in HEV and the polypeptides II, V, VI, and VII were identified in MSD virus and virus of SMC. The bands of penton base (polypeptide III) and fiber (polypeptide IV) were seen in HEV only by protein immunoblotting.

Studies on the aetiology of hydropericardium syndrome (Angara disease) in broilers.

The study was carried out to determine the aetiological agent(s) associated with hydropericardium syndrome (Angara disease) in broilers in Pakistan. The results indicate that in addition to adenovirus some other agent is involved in causing the disease but that this agent requires co-infection by an adenovirus for the reproduction of the typical signs of the syndrome. The nature of this agent remains unknown because no discrete virus or virus-like particle could be seen by electron microscopy.

Avian adenovirus isolated from pigeons affected with inclusion body hepatitis.

Avian adenoviruses were isolated from two pigeons affected with inclusion body hepatitis (IBH) by using chicken embryo liver cell cultures. One of the isolates, designated strain S-PL1, replicated in the cell nuclei forming intranuclear inclusion bodies, showed adenovirus-like morphology by electron microscopy, and cross-reacted serologically with strain SR-48 known as serotype 2 of fowl adenovirus. The strain S-PL1 killed day-old chicks by subcutaneous inoculation, and its 50% chicken lethal dose was 10(3.8) plaque forming units per bird. Severe lesions characterized with IBH and pancreatitis, were produced in chicks inoculated with the virus. Intranuclear inclusion bodies were also recognized in the liver, pancreas, kidney, proventriculus, small intestine, and caecum. By indirect immunofluorescence test, intranuclear viral antigens were detected in the liver, pancreas and other tissues.