Characterization of a herpesvirus associated with tracheitis in Gouldian finches (Erythrura [Chloebia] gouldiae)

Naturally occurring psittacid alphaherpesvirus 3 and probable adenovirus coinfection in an Indian ringneck parakeet in the United States

Psittacid alphaherpesvirus 3 (PsAHV-3) is a rarely reported virus that has been associated with pneumonia in psittacine birds. A 5-mo-old Indian ringneck parakeet (syn. rose-ringed parakeet; Psittacula krameri) was euthanized after developing torticollis and lethargy. Postmortem examination of the parakeet revealed severe pneumonia with syncytial cells containing eosinophilic intranuclear inclusion bodies (INIBs) in the respiratory epithelium. Gene sequencing of total DNA extraction detected PsAHV-3 in the frozen lung. The pancreas had severe lytic necrosis, with the remaining parenchymal cells expanded by large basophilic INIBs. Electron microscopy of the pancreas revealed intranuclear paracrystalline arrays of viral particles morphologically resembling adenovirus. Although we found 3 PsAHV-3 cases in birds in a literature search, we found no cases with adenoviral coinfection.

Emerging and Novel Viruses in Passerine Birds

There is growing interest in emerging viruses that can cause serious or lethal disease in humans and animals. The proliferation of cloacal virome studies, mainly focused on poultry and other domestic birds, reveals a wide variety of viruses, although their pathogenic significance is currently uncertain. Analysis of viruses detected in wild birds is complex and often biased towards waterfowl because of the obvious interest in avian influenza or other zoonotic viruses. Less is known about the viruses present in the order Passeriformes, which comprises approximately 60% of extant bird species. This review aims to compile the most significant contributions on the DNA/RNA viruses affecting passerines, from traditional and metagenomic studies. It highlights that most passerine species have never been sampled. Especially the RNA viruses from Flaviviridae, Orthomyxoviridae and Togaviridae are considered emerging because of increased incidence or avian mortality/morbidity, spread to new geographical areas or hosts and their zoonotic risk. Arguably poxvirus, and perhaps other virus groups, could also be considered "emerging viruses". However, many of these viruses have only recently been described in passerines using metagenomics and their role in the ecosystem is unknown. Finally, it is noteworthy that only one third of the viruses affecting passerines have been officially recognized.

Metatranscriptomic Comparison of Viromes in Endemic and Introduced Passerines in New Zealand

New Zealand/Aotearoa has many endemic passerine birds vulnerable to emerging infectious diseases. Yet little is known about viruses in passerines, and in some countries, including New Zealand, the virome of wild passerines has been only scarcely researched. Using metatranscriptomic sequencing we characterised the virome of New Zealand endemic and introduced species of passerine. Accordingly, we identified 34 possible avian viruses from cloacal swabs of 12 endemic and introduced bird species not showing signs of disease. These included a novel siadenovirus, iltovirus, and avastrovirus in the Eurasian blackbird (Turdus merula, an introduced species), song thrush (Turdus philomelos, introduced) and silvereye/tauhou (Zosterops lateralis, introduced), respectively. This is the first time novel viruses from these genera have been identified in New Zealand, likely reflecting prior undersampling. It also represents the first identification of an iltovirus and siadenovirus in blackbirds and thrushes globally. These three viruses were only found in introduced species and may pose a risk to endemic species if they were to jump species boundaries, particularly the iltoviruses and siadenoviruses that have a prior history of disease associations. Further virus study and surveillance are needed in New Zealand avifauna, particularly in Turdus populations and endemic species.

Detection of Herpesviruses in Wild Bird Casualties in Slovenia

The complete host range of avian herpesviruses in wild birds is unknown, and information about nucleotide sequences is available only in limited cases. The aim of this study was to detect the presence of herpesviruses in wild birds and to gain more information about their phylogenetic relationship. Oropharyngeal and cloacal swabs from 447 wild birds from 15 different orders presented as wildlife casualties were examined for herpesvirus presence with PCR targeting a fragment of the DNA polymerase gene. Herpesviruses were detected in oropharyngeal and/or cloacal swabs in 34 (7.5%) birds belonging to 11 species from six different avian orders: Accipitriformes, Charadriiformes, Columbiformes, Falconiformes, Passeriformes, and Strigiformes. The results of phylogenetic analysis showed that various herpesviruses sequences are present in the wild bird population. Some herpesviruses are host species–specific, whereas in some cases very similar sequences were detected through different avian orders, which confirms findings that herpesviruses are not always restricted to bird species. It seems that herpesvirus transmission could occur by predation from avian prey, and even by superpredation—for example, large owls, such as the Eurasian eagle owl (Bubo bubo) or Ural owl (Strix uralensis), preying on smaller raptors. This can lead to greater infection exposure and is in line with the fact that raptors were the most infected species group. Nevertheless, the individual or simultaneous detection of herpesviruses in oropharyngeal and cloacal swabs shows that both swab samples should be used for herpesvirus detection in wild birds.

Herpetic Pneumonia in Indian Ringneck Parrots (Psittacula krameri): First Report of Novel Psittacid Alphaherpesvirus-5 Infection in Europe

The first two European outbreaks of herpetic pneumonia caused by Psittacid alphaherpesvirus-5 were diagnosed based on gross pathology findings, histological examination, transmission electron microscopy visualization and genome sequencing. The outbreaks, characterized by high morbidity and high mortality rates, involved two parrot species, namely the Indian ringneck parrot (Psittacula krameri) and the Alexandrine parakeet (Psittacula eupatria). Clinical signs observed were ruffled feathers, dyspnea, tail bobbing, open wings while breathing, depression and anorexia. Necropsy was performed on Indian ringneck parrots only, and the most evident and serious gross lesion found in all the birds was a diffuse marked consolidation of the lungs associated with parenchyma congestion and oedema. Histological examination confirmed the existence of bronchopneumonia characterized by the presence of syncytial cells with intranuclear inclusion bodies. In one bird, fibrinous airsacculitis was observed as well. Lung tissue inspection through electron microscopy revealed the presence of virus particles resembling herpesviruses. Viral DNA was extracted, amplified using primers for Alloherpesviridae DNA polymerase gene detection, and then sequenced. BLAST analysis showed a 100% identity with the only previously reported sequence of PsHV-5 (MK955929.1).

DETECTION OF HERPESVIRUSES IN PASSERINE BIRDS CAPTURED DURING AUTUMN MIGRATION IN SLOVENIA

Herpesviruses (HVs) were detected by PCR in the cloacal swabs of 0.76% (4/525) clinically healthy free-living passerine birds from 32 different species captured in mist nets in Slovenia during the 2014 and 2017 autumn migrations. Herpesviruses were detected in the Eurasian Blackcap (Sylvia atricapilla), the Common Blackbird (Turdus merula), and the Eurasian Blue Tit (Cyanistes caeruleus). Phylogenetic analysis of partial DNA polymerase gene nucleotide sequences of the HV strains showed a distant relationship with other alphaherpesviruses of birds. In the phylogenetic tree, the HVs detected were clustered together with HV detected in Sulphur-crested Cockatoo and Neotropic Cormorants, as well as with known HVs such as gallid HV1, psittacid HV1 and HV2, and passerine HV1. Different sequences of HVs with relatively low identity were detected in our study, suggesting that different HVs were circulating in passerines sampled during the autumn migration in Slovenia.

Molecular and microscopic characterisation of a novel pathogenic herpesvirus from Indian ringneck parrots (Psittacula krameri)

A high morbidity, high mortality disease process caused flock deaths in an Indian ringneck parrot (Psittacula krameri) aviary flock in Victoria, Australia. Affected birds were either found dead with no prior signs of illness, or showed clinical evidence of respiratory tract disease, with snicking, sneezing and dyspnoea present in affected birds. Necropsy examinations performed on representative birds, followed by cytological and histopathological examination, demonstrated lesions consistent with a herpesvirus bronchointerstitial pneumonia. Transmission electron microscopy analysis of lung tissue demonstrated typical herpesvirus virions measuring approximately 220 nm in diameter. Next generation sequencing of genomic DNA from lung tissue revealed a highly divergent novel Psittacid alphaherpesvirus of the genus Iltovirus. Iltoviruses have been previously reported to cause respiratory disease in a variety of avian species, but molecular characterisation of the viruses implicated has been lacking. This study presents the genome sequence of a novel avian herpesvirus species designated Psittacid alphaherpesvirus-5 (PsHV-5), providing an insight into the evolutionary relationships of the alphaherpesviruses.

Genetically diverse herpesviruses in South American Atlantic coast seabirds

Different herpesviruses have been associated with respiratory and enteric disease and mortality among seabirds and waterfowl. In 2011, a respiratory disease outbreak affected 58.3% (98/168) of the Magellanic penguins undergoing rehabilitation due to an oil spill off the southern Brazilian coast. Etiology was attributed to a novel herpesvirus identified by histopathology, immunohistochemistry, electron microscopy and molecular studies with partial DNA sequencing. Since migration, rehabilitation and translocation may facilitate the spread of pathogens between populations and trigger the onset of clinical disease in animals with latent infections, investigation of herpesvirus occurrence in asymptomatic seabirds was performed. Samples from free-ranging seabirds were collected in Argentinian Patagonia (Magellanic penguins) and the Abrolhos Archipelago in Brazil (Brown boobies, Masked boobies, Red-billed tropicbirds, White-tailed tropicbirds and South American tern). Furthermore, asymptomatic seabirds housed at the facility where the outbreak occurred were also sampled. In total, 354 samples from eight seabird species were analyzed by PCR for herpesvirus. Four different sequences of herpesviruses were identified, one in Yellow-nosed Albatross, one in Boobies and Tropicbirds and two in Magellanic penguins. Magellanic penguin herpesvirus 1 was identified during the penguin outbreak at the rehabilitation facility in Brazil, while Magellanic penguin herpesvirus 2 was recovered from free-ranging penguins at four reproduction sites in Argentina. Phylogenic analysis of the herpesviruses sequences tentatively identified suggested that the one found in Suliformes and the one associated with the outbreak are related to sequences of viruses that have previously caused seabird die-offs. These findings reinforce the necessity for seabird disease surveillance programs overall, and particularly highlight the importance of quarantine, good hygiene, stress management and pre-release health exams in seabirds undergoing rehabilitation.

Outbreak of Herpesviral Conjunctivitis and Respiratory Disease in Gouldian Finches

An outbreak of tracheitis, sinusitis, and conjunctivitis, originating in recently imported birds, caused high morbidity and mortality in a flock of finches in Central Illinois. Although several species were present, Gouldian finches ( Erythrura [Chloebia] gouldiae) were most commonly and severely affected. Birds submitted for necropsy displayed microscopic lesions characteristic of herpesviral infection, including epithelial cytomegaly and karyomegaly with basophilic, intranuclear inclusion bodies in the nasopharynx, sinuses, trachea, parabronchi, conjunctiva, and occasionally the lacrimal gland or proximal proventricular glands. Viral particles consistent with herpesvirus were visualized within affected epithelial cells with electron microscopy. Based on a partial sequence of the viral DNA polymerase gene, this virus was found to be identical to a herpesvirus previously implicated in a similar outbreak in Canada and is most likely an alphaherpesvirus.

Phylogenetic characterization of a novel herpesvirus found in the liver and lungs of a Chilean flamingo (Phoenicopterus chilensis)

A novel herpesvirus was detected in a 17-day-old Chilean flamingo (Phoenicopterus chilensis) with pneumonia, hepatopathy, and severe anemia that was housed in California. Postmortem examination identified a pale, enlarged liver, mildly increased fluid in the lungs, and red foci in the spleen. Histologic examination revealed marked hepatic necrosis with syncytia, splenic necrosis, and interstitial pneumonia with eosinophilic intranuclear inclusions within hepatocytes and in unidentified cells of the lung. Transmission electron microscopy identified virions consistent with a herpesvirus in the nucleus and cytoplasm of degenerative hepatocytes. Nested consensus PCR, sequencing, and phylogenetic analysis identified a novel herpesvirus within the genus Iltovirus in the subfamily Alphaherpesvirinae.

A novel herpesvirus associated with respiratory disease in Bourke's parrots (Neopsephotus bourkii)

A novel herpesvirus infection in nine Bourke's parrots (Neopsephotus bourkii, formerly Neophema bourkii) housed in an outdoor aviary comprised of multiple species of birds was diagnosed based on histopathology, electron microscopy and polymerase chain reaction (PCR). Clinical signs in the parrots included anorexia, ruffled feathers, depression, loss of weight and respiratory distress. The most common gross lesions were moderately congested and oedematous lungs and a mild fibrinous exudate in the air sacs and lumen of the trachea. Histological examination revealed mild to severe bronchopneumonia and airsacculitis with syncytial cells containing eosinophilic intranuclear inclusion bodies in most birds. Other less frequent changes included tracheitis, syringitis, sinusitis, rhinitis, otitis media and conjunctivitis. Attempts to culture the virus in chicken embryos and chicken embryo liver cells were unsuccessful. Examination by transmission electron microscopy of syncytial cells from the lungs of two birds revealed intranuclear virus particles typical of the family Herpesviridae. DNA from a novel herpesvirus was amplified from lung tissue by PCR using degenerate primers derived from conserved avian herpesvirus sequences. The virus belongs in the genus Iltovirus of the Alphaherpesvirinae subfamily. It is not closely related to Psittacid herpesvirus 1 that causes Pacheco's disease but does group phylogenetically with a clade of herpesviruses that cause respiratory disease in a number of avian species. The proposed name for this herpesvirus is Psittacid herpesvirus 3.

Encephalitozoon hellem infection as the cause of a unilateral chronic keratoconjunctivitis in an umbrella cockatoo (Cacatua alba)

An umbrella cockatoo (Cacatua alba) was presented with a keratoconjunctivitis of 9 months' duration that was refractory to antibacterial and antifungal treatments. Microsporidian-type spores were observed in calcofluor M2R-stained cytological preparations of debrided corneal epithelium. Hematoxylin and eosin-stained sections of a conjunctival biopsy also showed a small number of intracellular parasites. Microsporidial DNA was detected by polymerase chain reaction in DNA extracted from the remaining biopsy material. Sequence analysis of the small subunit ribosomal RNA gene identified the microsporidium as Encephalitozoon hellem. The cockatoo was treated with oral albendazole for 3 months with resolution of the signs, and then again for 4 months when the signs returned. Since then, the bird has remained healthy for 2 years. This is the second report of a microsporidial keratoconjunctivitis in a bird, and the first report of an E. hellem infection in a cockatoo. Ophthalmologists should consider E. hellem as a possible cause of a keratoconjunctivitis in parrots that is refractory to treatment with traditional antimicrobials.

A novel psittacid herpesvirus found in African grey parrots (Psittacus erithacus erithacus)

DNA from a novel alphaherpesvirus was amplified from a cloacal papilloma, a cutaneous papilloma, and the normal cloacal mucosa of African grey parrots (Psittacus erithacus erithacus). Phylogenetically, the virus was most closely related to the psittacid herpesvirus, but demonstrated sufficient nucleotide and amino acid diversity to be considered a new alphaherpesvirus. It is proposed that the previously described psittacid herpesvirus be designated as psittacid herpesvirus 1 (PsHV-1), and this new species be classified as psittacid herpesvirus 2 (PsHV-2). It is speculated that PsHV-2 co-evolved with the African grey parrot and should therefore be present in these birds in the wild.

Phylogenetic analysis of the DNA polymerase gene of a novel alphaherpesvirus isolated from an Indian Gyps vulture

The DNA polymerase gene of a novel herpesvirus, vulture herpesvirus (VHV), isolated from an Indian Gyps vulture was completely sequenced using primer walking and transposon insertion strategies. DNA sequencing analysis revealed a single open reading frame (ORF) of 3660 nucleotides (53% G-C content) able to encode 1219 amino acids. Identification was based on a nucleotide sequence identity of approximately 50% to other herpesvirus sequences found in Genbank. Nine motifs were identified that are conserved amongst all known herpesviruses and are found within the 3'-5' exonuclease and DNA binding functional domains of the DNA polymerase enzyme. Phylogenetic analysis using Clustal W with neighbour-joining revealed VHV to group within the subfamily Alphaherpesvirinae, more closely related to the avian herpesviruses than to those of other species. Partial sequence data also revealed VHV to contain other genes fundamental to the structure and replication of all herpesvirus genomes. A Real Time PCR Taqman assay specific for the VHV DNA polymerase gene was designed to detect the presence of VHV genomic material in post mortem tissue samples from diseased birds. Positive tissues included the spleen, rectum, thymus, kidney and brain. A herpesvirus specific to vultures may pose a threat to the management of captive breeding programs being established to assist the survival of wild populations of Gyps vultures.