Pathology and Pathogenesis of Eurasian Blackbirds (Turdus merula) Naturally Infected with Usutu Virus.

The Usutu virus (USUV) is a mosquito-borne zoonotic flavivirus. Despite its continuous circulation in Europe, knowledge on the pathology, cellular and tissue tropism and pathogenetic potential of different circulating viral lineages is still fragmentary. Here, macroscopic and microscopic evaluations are performed in association with the study of cell and tissue tropism and comparison of lesion severity of two circulating virus lineages (Europe 3; Africa 3) in 160 Eurasian blackbirds (Turdus merula) in the Netherlands. Results confirm hepatosplenomegaly, coagulative necrosis and lymphoplasmacytic inflammation as major patterns of lesions and, for the first time, vasculitis as a novel virus-associated lesion. A USUV and Plasmodium spp. co-infection was commonly identified. The virus was associated with lesions by immunohistochemistry and was reported most commonly in endothelial cells and blood circulating and tissue mononucleated cells, suggesting them as a major route of entry and spread. A tropism for mononuclear phagocytes cells was further supported by viral labeling in multinucleated giant cells. The involvement of ganglionic neurons and epithelial cells of the gastrointestinal tract suggests a possible role of oral transmission, while the involvement of feather follicle shafts and bulbs suggests their use as a diagnostic sample for live bird testing. Finally, results suggest similar pathogenicity for the two circulating lineages.

A New Multiplex Real-Time RT-PCR for Simultaneous Detection and Differentiation of Avian Bornaviruses.

Avian bornaviruses were first described in 2008 as the causative agents of proventricular dilatation disease (PDD) in parrots and their relatives (Psittaciformes). To date, 15 genetically highly diverse avian bornaviruses covering at least five viral species have been discovered in different bird orders. Currently, the primary diagnostic tool is the detection of viral RNA by conventional or real-time RT-PCR (rRT-PCR). One of the drawbacks of this is the usage of either specific assays, allowing the detection of one particular virus, or of assays with a broad detection spectrum, which, however, do not allow for the simultaneous specification of the detected virus. To facilitate the simultaneous detection and specification of avian bornaviruses, a multiplex real-time RT-PCR assay was developed. Whole-genome sequences of various bornaviruses were aligned. Primers were designed to recognize conserved regions within the overlapping X/P gene and probes were selected to detect virus species-specific regions within the target region. The optimization of the assay resulted in the sensitive and specific detection of bornaviruses of Psittaciformes, Passeriformes, and aquatic birds. Finally, the new rRT-PCR was successfully employed to detect avian bornaviruses in field samples from various avian species. This assay will serve as powerful tool in epidemiological studies and will improve avian bornavirus detection.

Previous Usutu Virus Exposure Partially Protects Magpies (Pica pica) against West Nile Virus Disease But Does Not Prevent Horizontal Transmission.

The mosquito-borne flaviviruses USUV and WNV are known to co-circulate in large parts of Europe. Both are a public health concern, and USUV has been the cause of epizootics in both wild and domestic birds, and neurological cases in humans in Europe. Here, we explore the susceptibility of magpies to experimental USUV infection, and how previous exposure to USUV would affect infection with WNV. None of the magpies exposed to USUV showed clinical signs, viremia, or detectable neutralizing antibodies. After challenge with a neurovirulent WNV strain, neither viremia, viral titer of WNV in vascular feathers, nor neutralizing antibody titers of previously USUV-exposed magpies differed significantly with respect to magpies that had not previously been exposed to USUV. However, 75% (6/8) of the USUV-exposed birds survived, while only 22.2% (2/9) of those not previously exposed to USUV survived. WNV antigen labeling by immunohistochemistry in tissues was less evident and more restricted in magpies exposed to USUV prior to challenge with WNV. Our data indicate that previous exposure to USUV partially protects magpies against a lethal challenge with WNV, while it does not prevent viremia and direct transmission, although the mechanism is unclear. These results are relevant for flavivirus ecology and contention.

Genomic characterisation of a novel avipoxvirus, magpiepox virus 2, from an Australian magpie (Gymnorhina tibicen terraereginae).

Avipoxviruses are large, double-stranded DNA viruses and are considered significant pathogens that may impact on the conservation of numerous bird species. The vast majority of avipoxviruses in wild birds remain uncharacterised and their genetic variability is unclear. Here, we fully sequenced a novel avipoxvirus, magpiepox virus 2 (MPPV2), which was isolated 62 years ago (in 1956) from an Australian black-backed magpie. The MPPV2 genome was 298,392 bp in length and contained 419 predicted open-reading frames (ORFs). While 43 ORFs were novel, a further 24 ORFs were absent compared with another magpiepox virus (MPPV) characterised in 2018. The MPPV2 genome contained an additional ten genes that were homologs to shearwaterpox virus 2 (SWPV2). Subsequent phylogenetic analyses showed that the novel MPPV2 was most closely related to other avipoxviruses isolated from passerine and shearwater bird species, and demonstrated a high degree of sequence similarity (95.0%) with MPPV.

Molecular characterisation of a novel pathogenic avipoxvirus from an Australian passerine bird, mudlark (Grallina cyanoleuca).

Avipoxviruses have been recognised as significant pathogens in the conservation of numerous bird species. However, the vast majority of the avipoxviruses that infect wild birds remain uncharacterised. Here, we characterise a novel avipoxvirus, mudlarkpox virus (MLPV) isolated from an Australian passerine bird, mudlark (Grallina cyanoleuca). In this study, tissues with histopathologically confirmed lesions consistent with avian pox were used for transmission electron microscopy, and showed characteristic ovoid to brick-shaped virions, indicative of infectious particles. The MLPV genome was >342.7 Kbp in length and contained six predicted novel genes and a further six genes were missing compared to shearwaterpox virus-2 (SWPV-2). Subsequent phylogenetic analyses of the MLPV genome positioned the virus within a distinct subclade also containing recently characterised avipoxvirus genomes from shearwater, canary and magpie bird species, and demonstrated a high degree of sequence similarity with SWPV-2 (94.92%).

Molecular diagnosis of avian viruses in grassland passerines and captive yellow cardinals Gubernatrix cristata in Brazil / Diagnóstico molecular de vírus aviários em passeriformes campestres e cardeais-amarelos Gubernatrix cristata cativos no Brasil

Avian influenza viruses (AIVs), Newcastle disease virus (NDV), West Nile virus (WNV), adenovirus (AV) and herpesvirus (HV) play an important role in the health of human and animal populations. However, knowledge of the prevalence of these viruses in wild birds is restricted to some groups (e.g. shorebirds) or regions worldwide. Information on grassland birds of South America, which is essential for their conservation, is scarce. The objectives of the present study were to evaluate occurrences of AIV, NDV, WNV, AV and HV for the first time in a bird community of a unique protected area in southern Brazil, which is home for the critically endangered yellow cardinal (Gubernatrix cristata), and captive yellow cardinals from fauna maintainers of the Brazilian Captive Program of the Yellow Cardinal. Passerine species of wild life were caught, identified and samples (swabs) were collected from the oropharynx and cloaca of 64 passerines of 26 species (including 3 yellow cardinals) and 30 yellow cardinals of captive, for molecular diagnosis. The samples were subjected to RNA and DNA extraction and the real-time polymerase chain reaction (RT-PCR) for AIV, NDV and WNV and nested PCR for AV and HV. One yellow cardinal of captive presented a positive result for AV, this result is important for planning, managing natural attributes and making decisions in relation to integrated conservation of threatened species. This is the first report of AV in yellow cardinal and epidemiological investigation of viruses in wild passerines of the Pampa biome, in Rio Grande do Sul, Brazil.(AU)

Os vírus da gripe aviária (VGA), vírus da doença de Newcastle (VDN), vírus do Nilo Ocidental (VNO), adenovírus (AV) e herpesvírus (HV) desempenham um papel importante na saúde das populações humana e animal. No entanto, o conhecimento da prevalência desses vírus em aves selvagens é restrito a alguns grupos (por exemplo, aves limícolas) ou regiões em todo o mundo. As informações sobre as aves campestres da América do Sul, essenciais para a sua conservação, são escassas. Os objetivos do presente estudo foram avaliar a ocorrência de VGA, VDN, VNO, AV e HV pela primeira vez em uma comunidade de aves de uma área única protegida no Sul do Brasil, que abriga o cardeal-amarelo (Gubernatrix cristata) criticamente ameaçado de extinção e em cardeais-amarelos de cativeiro dos mantenedores de fauna do Programa Brasileiro de Cativeiro do Cardeal-amarelo. Espécies de passeriformes silvestres foram capturadas, identificadas e amostras (swabs) foram coletadas da orofaringe e cloaca de 64 passeriformes de 26 espécies (incluindo 3 cardeais-amarelos) e 30 cardeais-amarelos de cativeiro, para diagnóstico molecular. As amostras foram submetidas à extração de RNA e DNA e à reação em cadeia da polimerase em tempo real (RT-PCR) para VGA, VDN e VNO e nested PCR para AV e HV. Um cardeal-amarelo de cativeiro apresentou resultado positivo para AV, este resultado é importante para o planejamento, manejo dos atributos naturais e tomada de decisões em relação à conservação integrada de espécies ameaçadas. Este é o primeiro relato de AV em cardeal-amarelo e de investigação epidemiológica de vírus em passeriformes silvestres do bioma Pampa, no Rio Grande do Sul, Brasil.(AU)

Molecular Characterisation of a Novel and Highly Divergent Passerine Adenovirus 1.

Wild birds harbour a large number of adenoviruses that remain uncharacterised with respect to their genomic organisation, diversity, and evolution within complex ecosystems. Here, we present the first complete genome sequence of an atadenovirus from a passerine bird that is tentatively named Passerine adenovirus 1 (PaAdV-1). The PaAdV-1 genome is 39,664 bp in length, which was the longest atadenovirus to be sequenced, to the best of our knowledge, and contained 42 putative genes. Its genome organisation was characteristic of the members of genus Atadenovirus; however, the novel PaAdV-1 genome was highly divergent and showed the highest sequence similarity with psittacine adenovirus-3 (55.58%). Importantly, PaAdV-1 complete genome was deemed to contain 17 predicted novel genes that were not present in any other adenoviruses sequenced to date, with several of these predicted novel genes encoding proteins that harbour transmembrane helices. Subsequent analysis of the novel PaAdV-1 genome positioned phylogenetically to a distinct sub-clade with all others sequenced atadenoviruses and did not show any obvious close evolutionary relationship. This study concluded that the PaAdV-1 complete genome described here is not closely related to any other adenovirus isolated from avian or other natural host species and that it should be considered a separate species.

Body condition and poxvirus infection predict circulating glucose levels in a colorful songbird that inhabits urban and rural environments.

There is widespread contemporary interest in causes and consequences of blood glucose status in humans (e.g., links to diabetes and cardiovascular disease), but we know comparatively less about what underlies variation in glucose levels of wild animals. Several environmental factors, including diet, disease status, and habitat quality, may regulate glucose circulation, and we are in need of work that assesses many organismal traits simultaneously to understand the plasticity and predictability of glucose levels in ecological and evolutionary contexts. Here, we measured circulating glucose levels in a species of passerine bird (the house finch, Haemorhous mexicanus) that has served as a valuable model for research on sexual selection, disease, and urban behavioral ecology, as these animals display sexually dichromatic ornamental coloration, harbor many infectious diseases (e.g., poxvirus, coccidiosis, mycoplasmal conjunctivitis), and reside in both natural habitats and cities. We tested the effects of sex, habitat type, body condition, coccidiosis and poxvirus infections, and expression of carotenoid plumage coloration on blood glucose concentrations and found that the body condition and poxvirus infection significantly predicted circulating glucose levels. Specifically, birds with higher blood glucose levels had higher body condition scores and were infected with poxvirus. This result is consistent with biomedical, domesticated-animal, and wildlife-rehabilitation findings, and the premise that glucose elevation is a physiological response to or indicator of infection and relative body weight. The fact that we failed to find links between glucose and our other measurements suggests that blood glucose levels can reveal some but not all aspects of organismal or environmental quality.

Serum anti-Toxoplasma gondii antibodies in Passer domesticus (Linnaeus, 1758) (Passeriformes: Passeridae), in the municipality of Pelotas, RS, Brazil / Anticorpos séricos anti-Toxoplasma gondii em pardais, Passer domesticus (Linnaeus, 1758) (Passeriformes: Passeridae), do município de Pelotas, RS, Brasil

The objective of this study was to detect the presence of anti-Toxoplasma gondii antibodies in serum samples from 100 house sparrows (Passer domesticus Linnaeus, 1758) that were caught in the municipality of Pelotas, Rio Grande do Sul, Brazil. The modified agglutination test (MAT) was used to investigate anti-T. gondii antibodies and samples with a cut-off dilution > 5 were considered positive. Among the 100 serum samples analyzed, 80 (80%) were reactive. These results demonstrate that P. domesticus may play an important role in the epidemiological chain of T. gondii, since it is widely distributed throughout Brazil, and may act as a source of infection to domestic and wild felids.(AU)

O objetivo deste estudo foi detectar a presença de anticorpos anti-Toxoplasma gondii em amostras de soro de 100 pardais (Passer domesticus Linnaeus, 1758) capturados na área urbana do município de Pelotas, Rio Grande do Sul, Brasil. Para a pesquisa de anticorpos anti-T. gondii foi utilizado o teste de aglutinação modificado (MAT) e foram consideradas positivas as amostras que apresentaram título > 5. Das 100 amostras de soro analisadas, 80 (80%) foram reagentes. Esses resultados demonstram que P. domesticus, por ser amplamente distribuído em todo país, pode desempenhar um papel importante na cadeia epidemiológica de T. gondii, podendo atuar como fonte de infecção para felinos domésticos e silvestres.(AU)

Antiviral Activity and Adaptive Evolution of Avian Tetherins.

Tetherin/BST-2 is an antiviral protein that blocks the release of enveloped viral particles by linking them to the membrane of producing cells. At first, BST-2 genes were described only in humans and other mammals. Recent work identified BST-2 orthologs in nonmammalian vertebrates, including birds. Here, we identify the BST-2 sequence in domestic chicken (Gallus gallus) for the first time and demonstrate its activity against avian sarcoma and leukosis virus (ASLV). We generated a BST-2 knockout in chicken cells and showed that BST-2 is a major determinant of an interferon-induced block of ASLV release. Ectopic expression of chicken BST-2 blocks the release of ASLV in chicken cells and of human immunodeficiency virus type 1 (HIV-1) in human cells. Using metabolic labeling and pulse-chase analysis of HIV-1 Gag proteins, we verified that chicken BST-2 blocks the virus at the release stage. Furthermore, we describe BST-2 orthologs in multiple avian species from 12 avian orders. Previously, some of these species were reported to lack BST-2, highlighting the difficulty of identifying sequences of this extremely variable gene. We analyzed BST-2 genes in the avian orders Galliformes and Passeriformes and showed that they evolve under positive selection. This indicates that avian BST-2 is involved in host-virus evolutionary arms races and suggests that BST-2 antagonists exist in some avian viruses. In summary, we show that chicken BST-2 has the potential to act as a restriction factor against ASLV. Characterizing the interaction of avian BST-2 with avian viruses is important in understanding innate antiviral defenses in birds.IMPORTANCE Birds are important hosts of viruses that have the potential to cause zoonotic infections in humans. However, only a few antiviral genes (called viral restriction factors) have been described in birds, mostly because birds lack counterparts of highly studied mammalian restriction factors. Tetherin/BST-2 is a restriction factor, originally described in humans, that blocks the release of newly formed virus particles from infected cells. Recent work identified BST-2 in nonmammalian vertebrate species, including birds. Here, we report the BST-2 sequence in domestic chicken and describe its antiviral activity against a prototypical avian retrovirus, avian sarcoma and leukosis virus (ASLV). We also identify BST-2 genes in multiple avian species and show that they evolve rapidly in birds, which is an important indication of their relevance for antiviral defense. Analysis of avian BST-2 genes will shed light on defense mechanisms against avian viral pathogens.

Molecular identification of novel and genetically diverse adenoviruses in Passeriform birds.

Knowledge about adenoviruses in birds of the order Passeriformes is very scarce. Based on molecular characterizations, only two siadenoviruses, great tit adenovirus 1 and Gouldian finch adenovirus, have been described so far occurring in great tits and Gouldian finches, respectively. Assuming a broader occurrence of adenoviruses, various passeriform birds including pet, zoo, and wild birds were examined using a broad-range PCR targeting a fragment of the adenovirus DNA polymerase gene. Adenoviruses were detected in 25 individual birds belonging to 13 species and seven zoological families (Ploceidae, Fringillidae, Estrildidae, Paridae, Sylviidae, Turdidae, Muscicapidae). The putative viruses were further characterized by sequencing the PCR products and phylogenetic analyses. DNA of adenoviruses affiliating to 3 genera including aviadenovirus, siadenovirus, and atadenovirus was found. Viruses with sequences identical or closely related to great tit adenovirus 1 and Gouldian finch adenovirus 1 were detected in a great tit and in two zebra finches, respectively. Based on polymerase amino acid sequence comparisons, the viruses found in the remaining 22 birds revealed phylogenetic distances larger than 15% to adenoviruses known so far suggesting that they may belong to at least 14 different virus species. In some bird species (great tit, zebra finch, vitelline masked weaver) varying adenovirus genera were detected. These results suggest a broad variety of adenoviruses circulating in passeriform birds.

Evidence that Passerine Birds Act as Amplifying Hosts for Usutu Virus Circulation.

Environment determines the distribution and prevalence of vector-borne pathogens due to its direct and indirect effects on the hosts, vectors, and pathogens. To investigate the relationship between Usutu virus occurrence and host biodiversity and to characterize the nidus of infection, we used field-based measures of host diversity and density (all birds and only passerines), vector abundance, landscape and Usutu virus prevalence (mosquito infection rate), an emergent disease with a similar cycle to West Nile virus. We collected 908,237 female mosquitoes in an area of 54,984 ha in the Doñana National Park, southern Spain. We identified the mosquitoes and screened them for viruses, censused birds, characterized landscape and climatic variables, and then modeled the presence and infection rate of the virus in relation to host, vector, climatic, and landscape variables. Monthly Usutu presence, detected in Culex perexiguus, was positively related to Passeriformes richness and secondarily to NDVI in the previous month. Our results suggest that Usutu prevalence may be higher when and where host (passerine) richness was high, and thus challenging the conventional idea that host biodiversity reduces flavivirus amplification.

Usefulness of Eurasian Magpies (Pica pica) for West Nile virus Surveillance in Non-Endemic and Endemic Situations.

: In September 2017, passive surveillance allowed the detection of West Nile virus (WNV) lineage 2 for the first time in northern Spain in a northern goshawk (Accipiter gentilis). However, a cross sectional study carried out in Eurasian magpies (Pica pica) in a nearby area evidenced that WNV had been circulating two months earlier. Therefore, active surveillance in Eurasian magpies proved its effectiveness for the early detection of WNV in a non-endemic area. Further surveys in 2018 and the beginning of 2019 using young magpies (i.e., born after 2017) showed the repeated circulation of WNV in the same region in the following transmission season. Therefore, active surveillance in Eurasian magpies as well proved to be useful for the detection of WNV circulation in areas that may be considered as endemic. In this manuscript we present the results of those studies and discuss reasons that make the Eurasian magpies an ideal species for the surveillance of WNV, both in endemic and non-endemic areas.

A novel group of avian astroviruses from Neotropical passerine birds broaden the diversity and host range of Astroviridae.

Metagenomics is helping to expand the known diversity of viruses, especially of those with poorly studied hosts in remote areas. The Neotropical region harbors a considerable diversity of avian species that may play a role as both host and short-distance vectors of unknown viruses. Viral metagenomics of cloacal swabs from 50 Neotropical birds collected in French Guiana revealed the presence of four complete astrovirus genomes. They constitute an early diverging novel monophyletic clade within the Avastrovirus phylogeny, representing a putative new astrovirus species (provisionally designated as Avastrovirus 5) according to the International Committee on Taxonomy of Viruses (ICTV) classification criteria. Their genomic organization shares some characteristics with Avastrovirus but also with Mamastrovirus. The pan-astrovirus RT-PCR analysis of the cloacal samples of 406 wild Neotropical birds showed a community-level prevalence of 4.9% (5.1% in passerines, the highest described so far in this order of birds). By screening birds of a remote region, we expanded the known host range of astroviruses to the avian families Cardinalidae, Conopophagidae, Furnariidae, Thamnophilidae, Turdidae and Tyrannidae. Our results provide important first insights into the unexplored viral communities, the ecology, epidemiology and features of host-pathogen interactions that shape the evolution of avastroviruses in a remote Neotropical rainforest.

Flaviviruses in migratory passerines during spring stopover in a desert oasis.

Bird migration has long been hypothesized as the main mechanism for long-distance dispersal of flaviviruses, but the role of migratory birds in flaviviruses spillover is not well documented. In this study, we investigated the eco-epidemiology of West Nile virus (WNV) and Usutu virus (USUV) in trans-Saharan passerines during their spring stopover in southern Tunisian oases. To do, we combined oral swab analysis and serological tools to assess whether migratory birds could be reaching these stopover sites while infectious or have been previously exposed to viruses. All sampled birds tested negative for oral swab analysis. However, anti-WNV and anti-USUV antibodies were detected in 32% and 1% of tested birds, respectively. Among WNV-seropositive species, the Golden oriole (Oriolus oriolus) showed the highest anti-WNV occurrence probability. In this species, anti-WNV occurrence was twice larger in males than females. Inter-specific and intraspecific morphological, physiological and behavioural differences could explain these results. Although our findings did not show evidence for passerines migrating while infectious, they did not exclude an existing enzootic WNV transmission cycle in Tunisian oases. Further investigations including larger samples of migratory birds are needed for a better understanding of this issue.

Characterization of Unknown Orthobunya-Like Viruses from India.

Next-generation sequencing (NGS) of agents causing idiopathic human diseases has been crucial in the identification of novel viruses. This study describes the isolation and characterization of two novel orthobunyaviruses obtained from a jungle myna and a paddy bird from Karnataka State, India. Using an NGS approach, these isolates were classified as Cat Que and Balagodu viruses belonging to the Manzanilla clade of the Simbu serogroup. Closely related viruses in the Manzanilla clade have been isolated from mosquitos, humans, birds, and pigs across a wide geographic region. Since Orthobunyaviruses exhibit high reassortment frequency and can cause acute, self-limiting febrile illness, these data suggest that human and livestock infections of the Oya/Cat Que/Manzanilla virus may be more widespread and/or under-reported than anticipated. It therefore becomes imperative to identify novel and unknown viruses in order to understand their role in human and animal pathogenesis. The current study is a step forward in this regard and would act as a prototype method for isolation, identification and detection of several other emerging viruses.

Avian keratin disorder of Alaska black-capped chickadees is associated with Poecivirus infection.

BACKGROUND: Avian keratin disorder (AKD) is an epizootic of debilitating beak deformities, first documented in black-capped chickadees (Poecile atricapillus) in Alaska during the late 1990s. Similar deformities have now been recorded in dozens of species of birds across multiple continents. Despite this, the etiology of AKD has remained elusive, making it difficult to assess the impacts of this disease on wild populations. We previously identified an association between infection with a novel picornavirus, Poecivirus, and AKD in a small cohort of black-capped chickadees. METHODS: To test if the association between Poecivirus and AKD holds in a larger study population, we used targeted PCR followed by Sanger sequencing to screen 124 symptomatic and asymptomatic black-capped chickadees for Poecivirus infection. We further compared the efficacy of multiple non-terminal field sampling methods (buccal swabs, cloacal swabs, fecal samples, and blood samples) for Poecivirus screening. Finally, we used both in situ hybridization and a strand-specific expression assay to localize Poecivirus to beak tissue of AKD-positive individuals and to determine if virus is actively replicating in beak tissue. RESULTS: Poecivirus was detected in 28/28 (100%) individuals with AKD, but only 9/96 (9.4%) asymptomatic individuals with apparently normal beaks (p < 0.0001). We found that cloacal swabs are the most sensitive of these sample types for detecting Poecivirus in birds with AKD, but that buccal swabs should be combined with cloacal swabs in evaluating the infection status of asymptomatic birds. Finally, we used both in situ hybridization and a strand-specific expression assay to localize Poecivirus to beak tissue of AKD-positive individuals and to provide evidence of active viral replication. CONCLUSION: The data presented here show a strong, statistically significant relationship between Poecivirus infection and AKD, and provide evidence that Poecivirus is indeed an avian virus, infecting and actively replicating in beak tissue of AKD-affected BCCH. Taken together, these data corroborate and extend the evidence for a potential causal association between Poecivirus and AKD in the black-capped chickadee. Poecivirus continues to warrant further investigation as a candidate agent of AKD.

Health hazards to wild birds and risk factors associated with anthropogenic food provisioning.

Provision of supplementary food for wild birds at garden feeding stations is a common, large-scale and year-round practice in multiple countries including Great Britain (GB). While these additional dietary resources can benefit wildlife, there is a concomitant risk of disease transmission, particularly when birds repeatedly congregate in the same place at high densities and through interactions of species that would not normally associate in close proximity. Citizen science schemes recording garden birds are popular and can integrate disease surveillance with population monitoring, offering a unique opportunity to explore inter-relationships between supplementary feeding, disease epidemiology and population dynamics. Here, we present findings from a national surveillance programme in GB and note the dynamism of endemic and emerging diseases over a 25-year period, focusing on protozoal (finch trichomonosis), viral (Paridae pox) and bacterial (passerine salmonellosis) diseases with contrasting modes of transmission. We also examine the occurrence of mycotoxin contamination of food residues in bird feeders, which present both a direct and indirect (though immunosuppression) risk to wild bird health. Our results inform evidence-based mitigation strategies to minimize anthropogenically mediated health hazards, while maintaining the benefits of providing supplementary food for wild birds.This article is part of the theme issue 'Anthropogenic resource subsidies and host-parasite dynamics in wildlife'.

Complete coding sequence of a novel picorna-like virus in a blackbird infected with Usutu virus.

Using random high-throughput RNA sequencing, the complete coding sequence of a novel picorna-like virus (a 9,228-nt contig containing 212,202 reads) was determined from a blackbird (Turdus merula) infected with Usutu virus. This sequence shares only 36% amino acid sequence identity with its closest homolog, arivirus 1, (an unclassified member of the order Picornavirales), and shares its dicistronic genome arrangement. The new virus was therefore tentatively named "blackbird arilivirus" (ari-like virus). The nearly complete genome sequence consists of at least 9,228 nt and contains two open reading frames (ORFs) encoding the nonstructural polyprotein (2235 amino acids) and structural polyprotein (769 amino acids). Two TaqMan RT-qPCR assays specific for ORF1 confirmed the presence of high levels of this novel virus in the original sample. Nucleotide composition analysis suggests that blackbird arilivirus is of dietary (plant) origin.

Identification of two novel CRESS DNA viruses associated with an Avipoxvirus lesion of a blue-and-gray Tanager (Thraupis episcopus).

The discovery of circular rep-encoding single stranded (CRESS) DNA viruses has increased spectacularly over the past decade. They represent the smallest animal viruses known worldwide infecting a wide variety of invertebrates and vertebrates in different natural and human-made environments. The extremely low similarity of nucleotide and protein sequences among different CRESS DNA genomes has challenged their classification. Moreover, the existence of capsid proteins (Cp) remains difficult to demonstrate which is crucial to understand the structural properties of these viruses. Here we describe two unclassified CRESS DNA viruses isolated from a cutaneous lesion, caused by a strain of Avipoxvirus, from a blue-and-gray tanager (Thraupis episcopus) in Southern Ecuador. Both viruses present replication-associated proteins (Rep) and one to two open reading frames (ORF), one of which represents a putative Cp. The two new Rep are long proteins characterized by the existence of the several highly conserved amino acid residues characteristic of rolling circle replication. Within the putative Cp we detected intrinsically disordered regions (IDR), potential protein and DNA binding regions, and nuclear localization signals (NLS), providing further evidence of presumed Cp. Despite being found on the same host lesion, both viruses show low similarity between each other (<60%) and other known CRESS DNA viruses. Furthermore, we analyze the evolutionary relationships within the CRESS DNA diversity. Additional sampling is needed to explore the possible pathogenic effects, prevalence and diversity (both phylogenetical and structural) of these viruses in wild bird populations.