Molecular characterization of a recently identified circovirus in zebra finches (Taeniopygia guttata) associated with immunosuppression and opportunistic infections.

A recently identified circovirus (family Circoviridae) was detected in 14 zebra finches (Taeniopygia guttata) from seven aviaries and hobbyist breeders using polymerase chain reaction followed by sequencing. Full genome sequences of virus strains from six zebra finches consistently revealed characteristic circoviral genomic features such as a stem-loop structure and two major open reading frames (ORFs) encoding the replication-associated protein and the putative capsid protein. One further ORF encoding a protein of unknown function was additionally identified in all six genomes. Based on full genome nucleotide comparison, zebra finch circovirus was most similar to Finch circovirus originating from a Gouldian finch (Chloebia gouldiae) sharing 78% nucleotide identity. High genetic diversity was detected in the circoviruses from individual zebra finches. Comparison of the six full genome sequences revealed two genetic subgroups, which shared pairwise nucleotide identities between 91.4% and 92.7%. Analyses including partial sequences of the replication-associated protein gene of the zebra finch circovirus strains from all 14 birds supported the existence of two main clusters. Clinical diseases associated with circovirus infection were found in nestlings, fledglings and adult birds and varied from mild to severe with high mortality caused by secondary infections. Macrorhabdus ornithogaster was the most frequently detected opportunistic pathogen. Feathering disorders were seen in two birds. Lymphocytic depletion of the spleen and leukocytopaenia were detected in individual birds, suggesting immunosuppression and a pathogenesis common to circovirus infections in other birds.

Occurrence of avian bornavirus infection in captive psittacines in various European countries and its association with proventricular dilatation disease.

A total of 1442 live birds and 73 dead birds out of 215 bird collections in Spain, Germany, Italy, the UK and Denmark were tested for avian bornavirus (ABV) infection by four different methods. The majority of the birds were psittacines belonging to 54 different genera of the order Psittaciformes. In total, 22.8% of the birds reacted positive for ABV in at least one of the tests. Combined testing of swabs from the crop and cloaca, and serum for the diagnosis of ABV infection in live birds revealed that virus shedding and antibody production coincided in only one-fifth of the positive birds so that the examination of these three samples is recommended for reliable ABV diagnosis. By statistical analysis of this large number of samples, the ABV infection proved to be highly significant (P <0.001) associated with histopathologically confirmed proventricular dilatation disease (PDD) in dead birds as well as with clinically assumed PDD in live birds. However, ABV infection was also detected in psittacines without pathological lesions or clinical signs of PDD. Twelve non-psittacine birds belonging to the genera Aburria, Ciconia, Geopelia, Leucopsar and Pavo were tested negative for ABV infection. Within the order of Psittaciformes, birds belonging to 33 different genera reacted positive for ABV. In 16 of these psittacine genera, the ABV infection was demonstrated for the first time. The present study emphasizes the widespread occurrence of clinically variable ABV infections in Europe by analysing a large number of specimens from a broad range of bird species in several assays.

Haemoproteus minutus is highly virulent for Australasian and South American parrots.

BACKGROUND: Haemoproteus and Plasmodium species are widespread avian blood parasites. Several Plasmodium species are known for their high virulence and have caused significant declines in naïve bird populations. The impact of closely related Haemoproteus parasites is largely unknown. Recently we reported a lethal disease in two parrot aviaries caused by Haemoproteus parasites. RESULTS: Here we show that the causative pathogen Haemoproteus minutus is responsible for further 17 lethal outbreaks in parrot aviaries in Denmark, Germany and Great Britain. All affected parrots are endemic to Australasia and South America. We sequenced the cytochrome b gene from megalomeront-infected muscle tissue of 21 parrots and identified the two lineages TUPHI01 and TURDUS2 as causative agents, commonly naturally infecting the common blackbird (Turdus merula) and the song thrush (Turdus philomelos), respectively, in the Palaearctic. No intraerythrocytic parasite stages were found in any of the parrots. We failed to detect H. minutus in invasive Indian ring-necked parakeets (Psittacula krameri) in Germany. Together this suggests that abortive infections with two virulent lineages of H. minutus are lethal for naïve parrot species from Australasia and South America. We asked whether we could detect H. minutus in New Zealand, where its Turdus hosts were introduced in the 1800s. We therefore tested invasive blackbirds and song thrushes, and the co-existing endemic red-fronted parakeet (Cyanoramphus novaezelandiae) population on three New Zealand islands. No Haemoproteus spp. DNA was detected in all blood samples, indicating absence of transmission. CONCLUSIONS: The results of this study show that captive parrots in Europe are threatened by two lineages of an otherwise benign parasite of Turdus spp. Aviary collections of parrots should be protected from Culicoides spp. vectors in Europe. Animal trade and climate changes extending the current vector and parasite distribution have to be considered as potential risk factors for the introduction of the disease in naïve parrot populations.

Physiology, diagnosis, and diseases of the avian reproductive tract.

Disorders of the reproductive system represent a large portion of both large and small domestic animal medicine. Although some disorders of this system have been extensively studied in birds, this science is still in its infancy, when compared to mammalian reproductive medicine. This may be due to several reasons, but the simple fact that birds are oviparous renders knowledge of mammalian reproductive anatomy, histology, physiology, and disease process, inapplicable to avian patients. Nevertheless, several specific diseases or conditions affecting the reproductive system of birds have been described. By integrating information about the comparative anatomy and physiology of birds, reports of the most common reproductive diseases of birds and utilizing the latest diagnostic techniques, especially videoendoscopy, the avian practitioner should be able to diagnose and properly treat a high percentage of the avian reproductive diseases.

Investigations on the aetiology of pinching off syndrome in four white-tailed sea eagles (Haliaeetus albicilla) from Germany.

The purpose of this study was to investigate the aetiology of the pinching off syndrome (POS), a generalized feather abnormality affecting free-living nestling of the white-tailed sea eagle (Haliaeetus albicilla) in Europe. For the first time, extensive clinical, haematological, biochemical, virological, bacteriological, nutritional, histopathological, parasitological and electron microscopical examinations were performed on three females and one male suffering from POS. Early and increased cytokeratin formation at the base of regenerating feathers and their follicle was observed in affected birds. Ultrathin sections of the feather papillae revealed an extended stratum transitivum and a compact, thickened keratinized stratum corneum. The transitional cells in POS feathers contained vacuoles often associated with the nucleus. Lipofuscin accumulations in neurons, glial cells and islet cells of the pancreas were found in all examined birds. It was not clear whether there is an association between the occurrence of lipofuscin and POS. No evidence was found to suggest that infectious agents (parasites, bacteria, fungi or viruses), malnutrition or hormonal imbalances are involved in the aetiology of POS in white-tailed sea eagles. It remains unclear whether there is a genetic background of POS.

Investigation of several selected adjuvants regarding their efficacy and side effects for the production of a vaccine for parakeets to prevent a disease caused by a paramyxovirus type 3.

The infection with paramyxovirus type 3 (PMV-3) of parakeets can lead to severe illness in small psittacines (Neophema spp. and other parakeets) as well as in passerines (finches). The disease is characterized by acute or chronical pancreatitis and central nervous symptoms, such as torticollis as well as walking in circles and by high mortality rates in the affected flocks. As there is no licensed vaccine for psittacines available to prevent this disease. The aim of the following study was to find a suitable vaccine formulation for parakeets with inactivated PMV-3 and a well-tolerated and effective adjuvant. Seven adjuvants have been examined in ovo and in vivo regarding their efficacy and side effects. In these investigations, the classical Freund's complete Adjuvant (FCA) and Freund's incomplete Adjuvant (FICA) and Alhydrogel, but also the more recent developments TiterMax Gold, Specol, Gerbu Adjuvant 100, and Diluvac Forte have been used. Regarding its efficacy and side effects, the vaccine formulation "PMV-3/Specol" has been evaluated positively and can be recommended for the production of a PMV-3 vaccine for parakeets.

Nucleotide sequence analysis of a C1 gene fragment of psittacine beak and feather disease virus amplified by real-time polymerase chain reaction indicates a possible existence of genotypes.

To investigate sequence diversity of psittacine beak and feather disease virus, samples collected from 31 psittacine species with or without clinical signs were tested for the presence of the viral genome. A real-time polymerase chain reaction was developed amplifying a 202 base pair fragment of the region encoding the capsid protein C1 and detecting 100 to 1000 genome equivalents. The nucleotide sequences of the polymerase chain reaction products showed 84.1 to 100% identity with no consistent pattern with regard to the infected bird species. Amino acid exchanges were concentrated mainly in five of the 42 deduced positions. Sequences obtained from an outbreak of acute beak and feather disease in lories clustered in a separate branch of a phylogenetic tree. Sequences in samples from African grey parrots with feather disorders grouped together, whereas those from the same species with immunosuppression clustered in other branches. These results indicate the possible existence of beak and feather disease virus genotypes.