Deadly avian flu hits Galápagos.

Concerns rise for boobies, finches, and other endemic species.

Sensitivity of Quails (Coturnix coturnix), Siskins (Carduelis spinus), and Frogs (Rana ridibunda) to West Nile Virus.

The level of viremia and features of the course of experimental infection caused by West Nile virus were studied in two species of migratory birds, siskins Сarduelis spinus and quails Coturnix coturnix, and in one species of amphibians, frogs Rana ridibunda. In quails, the virus caused a fatal disease; histological analysis revealed pathological changes in the heart, kidneys, liver, and brain stem. In siskins and frogs, virus antigen was detected in cloacal smears despite the absence of clinical manifestations, the level of viremia was sufficient to infect insect vectors during bloodsucking. These findings suggest that siskins and frogs can be potential reservoirs of West Nile virus and play a role in its circulation.

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.

Diverse genomoviruses representing eight new and one known species identified in feces and nests of house finches (Haemorhous mexicanus).

House finches are desert birds native to Mexico and the southwestern United States of America. They are relatively well studied in terms of their diet, breeding, and migration patterns, but knowledge regarding viruses associated with these birds is limited. DNA viruses in fecal and nest samples of finches sampled in Phoenix (Arizona, USA) were identified using high-throughput sequencing. Seventy-three genomoviruses were identified, belonging to four genera: Gemycircularvirus (n = 27), Gemykibivirus (n = 41), Gemykroznavirus (n = 3) and Gemykrogvirus (n = 2). These 73 finch genomoviruses represent nine species, eight of which are novel. This study reiterates that these genomoviruses are ubiquitous in ecosystems.

Spatio-temporal dynamics and aetiology of proliferative leg skin lesions in wild British finches.

Proliferative leg skin lesions have been described in wild finches in Europe although there have been no large-scale studies of their aetiology or epizootiology to date. Firstly, disease surveillance, utilising public reporting of observations of live wild finches was conducted in Great Britain (GB) and showed proliferative leg skin lesions in chaffinches (Fringilla coelebs) to be widespread. Seasonal variation was observed, with a peak during the winter months. Secondly, pathological investigations were performed on a sample of 39 chaffinches, four bullfinches (Pyrrhula pyrrhula), one greenfinch (Chloris chloris) and one goldfinch (Carduelis carduelis) with proliferative leg skin lesions and detected Cnemidocoptes sp. mites in 91% (41/45) of affected finches and from all species examined. Fringilla coelebs papillomavirus (FcPV1) PCR was positive in 74% (23/31) of birds tested: a 394 base pair sequence was derived from 20 of these birds, from all examined species, with 100% identity to reference genomes. Both mites and FcPV1 DNA were detected in 71% (20/28) of birds tested for both pathogens. Histopathological examination of lesions did not discriminate the relative importance of mite or FcPV1 infection as their cause. Development of techniques to localise FcPV1 within lesions is required to elucidate the pathological significance of FcPV1 DNA detection.

West Nile and St. Louis encephalitis viral genetic determinants of avian host competence.

West Nile virus (WNV) and St. Louis encephalitis (SLEV) virus are enzootically maintained in North America in cycles involving the same mosquito vectors and similar avian hosts. However, these viruses exhibit dissimilar viremia and virulence phenotypes in birds: WNV is associated with high magnitude viremias that can result in mortality in certain species such as American crows (AMCRs, Corvus brachyrhynchos) whereas SLEV infection yields lower viremias that have not been associated with avian mortality. Cross-neutralization of these viruses in avian sera has been proposed to explain the reduced circulation of SLEV since the introduction of WNV in North America; however, in 2015, both viruses were the etiologic agents of concurrent human encephalitis outbreaks in Arizona, indicating the need to re-evaluate host factors and cross-neutralization responses as factors potentially affecting viral co-circulation. Reciprocal chimeric WNV and SLEV viruses were constructed by interchanging the pre-membrane (prM)-envelope (E) genes, and viruses subsequently generated were utilized herein for the inoculation of three different avian species: house sparrows (HOSPs; Passer domesticus), house finches (Haemorhous mexicanus) and AMCRs. Cross-protective immunity between parental and chimeric viruses were also assessed in HOSPs. Results indicated that the prM-E genes did not modulate avian replication or virulence differences between WNV and SLEV in any of the three avian species. However, WNV-prME proteins did dictate cross-protective immunity between these antigenically heterologous viruses. Our data provides further evidence of the important role that the WNV / SLEV viral non-structural genetic elements play in viral replication, avian host competence and virulence.

A novel passerivirus (family Picornaviridae) in an outbreak of enteritis with high mortality in estrildid finches (Uraeginthus sp.).

An enteric outbreak with high mortality (34/52, 65.4%) was recorded in 2014 in home-reared estrildid finches (Estrildidae) in Hungary. A novel passerivirus was identified in a diseased violet-eared waxbill using viral metagenomics and confirmed by RT-(q)PCR. The complete genome of finch picornavirus strain waxbill/DB01/HUN/2014 (MF977321) showed the highest amino acid sequence identity of 38.9%, 61.6%, 69.6% in P1cap, 2Chel and 3CproDpol, respectively, to passerivirus A1 (GU182406). A high viral load (6.58 × 1010 genomic copies/ml) was measured in a cloacal specimen and in the tissues (spinal cord, lung, and the intestines) of two additional affected finches. In addition to intestinal symptoms (diarrhoea), the presence of extra-intestinal virus suggests a generalized infection in this fatal disease, for which the passerivirus might be a causative agent.

An examination of the effect of aerosolized Permanone insecticide on zebra finch susceptibility to West Nile virus.

West Nile virus (WNV) is maintained cryptically primarily in avian (passerine) populations, where it is transmitted by Culex spp. mosquitoes. Mosquito-control measures currently include physical activities to reduce mosquito-breeding sites and the application of mosquito larvicides or aerosolized insecticides to kill adults (adulticides) when arboviral diseases such as WNV or Zika virus are detected in mosquito populations. Organochlorine, organophosphorus, carbamate, and pyrethroid insecticides are often used. Previous work suggests an effect of pyrethroids on the immune system in a variety of vertebrates. We examined the effects of exposure to aerosolized Permanone® 30:30 insecticide (permethrin and piperonyl butoxide in soy oil vehicle) at approximately 103 to 106 times potential environmental concentrations on the response of captive zebra finches (Taeniopygia guttata) to experimental challenge with WNV. Compared to vehicle control birds, WNV outcome was unchanged (65% of birds produced a viremia) in the "low" exposure (9.52 ± 3.13 mg/m3 standard deviation [SD] permethrin) group but reduced in the "high" exposure (mean 376.5 ± 27.9 mg/m3 SD permethrin) group (30% were viremic; p < 0.05). After clearing WNV infection, birds treated with Permanone regained less body mass than vehicle-treated birds (p < 0.001). The present study suggests that exposure to aerosolized Permanone insecticide at levels exceeding typical application rates has the potential to not change or to mildly enhance a bird's resistance to WNV. Environ Toxicol Chem 2017;36:3376-3386. Published 2017 Wiley Periodicals Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Polyomavirus Infection in Gouldian Finches (Erythrura gouldiae) and Other Pet Birds of the Family Estrildidae.

A syndrome characterized by apathy, diarrhoea and high mortality of nestlings was observed in a flock of pet birds of the family Estrildidae. Enlargement of the liver, pulmonary congestion and urate accretions in the kidney were observed. Microscopically, there was glomerular atrophy, oedema and congestion of the lungs and necrosis and fibrosis of the liver. Cowdry type B intranuclear inclusion bodies were detected in the tissues. Polyomavirus was detected by polymerase chain reaction. The entire genome of the virus was amplified and sequenced, revealing 99 % identity to the sequence of finch polyomavirus isolated from the Eurasian bullfinch (family Fringillidae).

Susceptibility and Antibody Response of the Laboratory Model Zebra Finch (Taeniopygia guttata) to West Nile Virus.

Since the introduction of West Nile virus (WNV) into North America in 1999 a number of passerine bird species have been found to play a role in the amplification of the virus. Arbovirus surveillance, observational studies and experimental studies have implicated passerine birds (songbirds, e.g., crows, American robins, house sparrows, and house finches) as significant reservoirs of WNV in North America, yet we lack a tractable passerine animal model for controlled studies of the virus. The zebra finch (Taeniopygia guttata) serves as a model system across a diversity of fields, and here we develop the zebra finch a songbird model for WNV. Like many natural hosts of WNV, we found that zebra finches developed sufficient viremia to serve as a competent host, yet in general resisted mortality from infection. In the Australian zebra finch (AZF) T. g. castanotis, we detected WNV in the majority of sampled tissues by 4 days post injection (dpi). However, WNV was not detected in tissues of sacrificed birds at 14 dpi, shortly after the development of detectable anti-WNV antibodies in the majority of birds indicating successful viral clearance. We compared susceptibility between the two zebra finch subspecies AZF and Timor zebra finch (TZF) T. g. guttata. Compared to AZF, WNV RNA was detected in a larger proportion of challenged TZF and molecular detection of virus in the serum of TZF was significantly higher than in AZF. Given the observed moderate host competence and disease susceptibility, we suggest that zebra finches are appropriate as models for the study of WNV and although underutilized in this respect, may be ideal models for the study of the many diseases carried and transmitted by songbirds.

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.

Comparing competitive fitness of West Nile virus strains in avian and mosquito hosts.

Enzootic transmission of West Nile virus (WNV; Flaviviridae, Flavivirus) involves various species of birds and ornithophilic mosquitoes. Single nucleotide substitutions in the WNV genome may impact viral fitness necessary for WNV adaptation and evolution as previously shown for the WN02 genotype. In an effort to study phenotypic change, we developed an in vivo fitness competition model in two biologically relevant hosts for WNV. The House Finch (HOFI; Haemorhous mexicanus) and Culex tarsalis mosquitoes represent moderately susceptible hosts for WNV, are highly abundant in Western North America and frequently are infected with WNV in nature. Herein, we inoculated HOFIs and Cx. tarsalis competitively (dually) and singly with infectious-clone derived viruses of the founding California isolate COAV997-2003 (COAV997-IC), the founding North American isolate NY99 (NY99-IC), and a 2004 field isolate from California (CA-04), and compared the replicative capacities (fitness) of these viruses to a genetically marked virus of COAV997 (COAV997-5nt) by measuring RNA copy numbers. COAV997 and COAV997-5nt exhibited neutral fitness in HOFIs and Cx. tarsalis, and the temperature-sensitive phenotype of COAV997 did not affect replication in HOFIs as none of the infected birds became febrile. The NY99 and CA-04 isolates demonstrated elevated fitness in HOFIs compared to COAV997-5nt, whereas all viruses replicated to similar titers and RNA copies in Cx. tarsalis, and the only fitness differences were related to infection rates. Our data demonstrated that competitive replication allows for the sensitive comparison of fitness differences among two genetically closely related viruses using relevant hosts of WNV while eliminating host-to-host differences. In conclusion, our approach may be helpful in understanding the extent of phenotypic change in fitness associated with genetic changes in WNV.

Influenza A(H7N9) virus transmission between finches and poultry.

Low pathogenicity avian influenza A(H7N9) virus has been detected in poultry since 2013, and the virus has caused >450 infections in humans. The mode of subtype H7N9 virus transmission between avian species remains largely unknown, but various wild birds have been implicated as a source of transmission. H7N9 virus was recently detected in a wild sparrow in Shanghai, China, and passerine birds, such as finches, which share space and resources with wild migratory birds, poultry, and humans, can be productively infected with the virus. We demonstrate that interspecies transmission of H7N9 virus occurs readily between society finches and bobwhite quail but only sporadically between finches and chickens. Inoculated finches are better able to infect naive poultry than the reverse. Transmission occurs through shared water but not through the airborne route. It is therefore conceivable that passerine birds may serve as vectors for dissemination of H7N9 virus to domestic poultry.

A novel siadenovirus detected in the kidneys and liver of Gouldian finches (Erythura gouldiae).

A novel siadenovirus was found in six captive Gouldian finches (Erythrura gouldiae) in the United States and Hungary. Histopathological examination revealed inclusions in the kidney of the captive Gouldian finch in the United States, and virions morphologically consistent with adenoviruses were seen by electron microscopy. Partial sequence of the DNA-dependent DNA polymerase gene was gained by consensus PCR and sequencing in all six finches, and all proved to be identical. In one Hungarian finch, additional sequence was obtained from the DNA polymerase gene, the pre-terminal protein (pTP) gene, the 52k gene, and the hexon gene. Bayesian, maximum likelihood, and distance-based analyses showed the novel virus clusters with the siadenoviruses, and is herein referred to as Gouldian finch adenovirus 1. The genes looked at in this study had low G+C percentages, which is common in the genus Siadenovirus, and suggestive of recent host switch. The significance of this virus' presence is unknown at this time as clinical signs of positive birds varied.

Discovery of a new avian bornavirus genotype in estrildid finches (Estrildidae) in Germany.

Avian bornaviruses (ABV) are known to be the causative agent of proventricular dilatation disease (PDD) in parrots and their relatives (Psittaciformes). A broad range of ABV genotypes has been detected not only in psittacine birds, but also in other avian species including canary birds (Serinus canaria forma domestica) and Bengalese finches (Lonchura striata f. dom.), which are both members of the order songbirds (Passeriformes). During this study 286 samples collected from captive and wild birds of various passerine species in different parts of Germany were screened for the presence of ABV. Interestingly, only three ABV-positive samples were identified by RT-PCR. They originated from one yellow-winged pytilia (Pytilia hypogrammica) and two black-rumped waxbills (Estrilda troglodytes) from a flock of captive estrildid finches in Saxony. The ABV isolates detected here were only distantly related to ABV isolates found in passerine species in Germany and Japan and form a new genotype tentatively called ABV-EF (for "estrildid finches").

A novel recombinant retrovirus in the genomes of modern birds combines features of avian and mammalian retroviruses.

UNLABELLED: Endogenous retroviruses (ERVs) represent ancestral sequences of modern retroviruses or their extinct relatives. The majority of ERVs cluster alongside exogenous retroviruses into two main groups based on phylogenetic analyses of the reverse transcriptase (RT) enzyme. Class I includes gammaretroviruses, and class II includes lentiviruses and alpha-, beta-, and deltaretroviruses. However, analyses of the transmembrane subunit (TM) of the envelope glycoprotein (env) gene result in a different topology for some retroviruses, suggesting recombination events in which heterologous env sequences have been acquired. We previously demonstrated that the TM sequences of five of the six genera of orthoretroviruses can be divided into three types, each of which infects a distinct set of vertebrate classes. Moreover, these classes do not always overlap the host range of the associated RT classes. Thus, recombination resulting in acquisition of a heterologous env gene could in theory facilitate cross-species transmissions across vertebrate classes, for example, from mammals to reptiles. Here we characterized a family of class II avian ERVs, "TgERV-F," that acquired a mammalian gammaretroviral env sequence. Although TgERV-F clusters near a sister clade to alpharetroviruses, its genome also has some features of betaretroviruses. We offer evidence that this unusual recombinant has circulated among several avian orders and may still have infectious members. In addition to documenting the infection of a nongalliform avian species by a mammalian retrovirus, TgERV-F also underscores the importance of env sequences in reconstructing phylogenies and supports a possible role for env swapping in allowing cross-species transmissions across wide taxonomic distances. IMPORTANCE: Retroviruses can sometimes acquire an envelope gene (env) from a distantly related retrovirus. Since env is a key determinant of host range, such an event affects the host range of the recombinant virus and can lead to the creation of novel retroviral lineages. Retroviruses insert viral DNA into the host DNA during infection, and therefore vertebrate genomes contain a "fossil record" of endogenous retroviral sequences thought to represent past infections of germ cells. We examined endogenous retroviral sequences in avian genomes for evidence of recombination events involving env. Although cross-species transmissions of retroviruses between vertebrate classes (from mammals to birds, for example) are thought to be rare, we here characterized a group of avian retroviruses that acquired an env sequence from a mammalian retrovirus. We offer evidence that this unusual recombinant circulated among songbirds 2 to 4 million years ago and has remained active into the recent past.

Evaluation of the pathogenicity of avipoxvirus strains isolated from wild birds in New Zealand and the efficacy of a fowlpox vaccine in passerines.

Avipoxvirus (APV) infection is a highly contagious disease of birds and has been reported in more than 200 bird species, affecting both domesticated and free-ranging birds around the world. In New Zealand, at least three different strains of Avipoxvirus (APV) have been identified in a range of bird species.The pathogenicityof two APV strains isolated from wild birds in New Zealand, representing subclade A1 and subclade B1 were compared in zebra finches (Taeniopygia guttata). The efficacy of fowlpox vaccine at preventing clinical disease in passerines was also evaluated. Twenty-five zebra finches were divided into five groups (I-IV and a control group). Birds from Groups II and IV were vaccinated using fowl poxvirus vaccine prior to challenge. Subsequently two groups (I and II) were inoculated with a silvereye isolate (A1) and the other two groups (Group III and IV) were inoculated with a blackbird isolate (B1). Both inocula were previously propagated in chicken fibroblast cell culture. Birds in the control group were inoculated with sterile PBS. Skin thickness at the inoculation sites was measured and the development of additional skin lesions was monitored. Antibody development was measured by ELISA pre- and post virus inoculation. Both APV strains caused either swelling or hyperplasia at the inoculation site of non-vaccinated birds (4/5 in Group I and 5/5 in Group III). The swelling was milder and no foot lesions were observed in vaccinated birds before or after challenge with the silvereye or blackbird APV strains. These findings indicated that the fowlpox vaccine provided safe and appropriate protection for zebra finches exposed to the two wild APV strains and suggest that the vaccine has the potential to be used where APV threatens the captive management or translocation of endangered passerines.

The genome of a Mesozoic paleovirus reveals the evolution of hepatitis B viruses.

Paleovirology involves the identification of ancient endogenous viral elements within eukaryotic genomes. The evolutionary origins of the reverse-transcribing hepatitis B viruses, however, remain elusive, due to the small number of endogenized sequences present in host genomes. Here we report a comprehensively dated genomic record of hepatitis B virus endogenizations that spans bird evolution from >82 to <12.1 million years ago. The oldest virus relic extends over a 99% complete hepatitis B virus genome sequence and constitutes the first discovery of a Mesozoic paleovirus genome. We show that Hepadnaviridae are >63 million years older than previously known and provide direct evidence for coexistence of hepatitis B viruses and birds during the Mesozoic and Cenozoic Eras. Finally, phylogenetic analyses and distribution of hepatitis B virus relics suggest that birds potentially are the ancestral hosts of Hepadnaviridae and mammalian hepatitis B viruses probably emerged after a bird-mammal host switch. Our study reveals previously undiscovered and multi-faceted insights into prehistoric hepatitis B virus evolution and provides valuable resources for future studies, such as in-vitro resurrection of Mesozoic hepadnaviruses.

Variation with land use of immune function and prevalence of avian pox in Galapagos finches.

Introduced disease has been implicated in recent wildlife extinctions and population declines worldwide. Both anthropogenic-induced change and natural environmental features can affect pathogen spread. Furthermore, environmental disturbance can result in changes in stress physiology, nutrition, and social structure, which in turn can suppress immune system function. However, it remains unknown whether landscape variation results in heterogeneity in host resistance to pathogens. Avian pox virus, a pathogen implicated in avian declines and extinctions in Hawaii, was introduced to the Galapagos in the 1890 s, and prevalence (total number of current infections) has increased recently in finches. We tested whether prevalence and recovery trends in 7 species of Galapagos finches varied by elevation or human land use. To do so, we used infection data obtained from 545 wild-caught birds. In addition, we determined whether annual changes in 4 aspects of innate immune function (complement protein activity, natural antibody activity, concentration of PIT54 protein, and heterophil:lymphocyte ratio) varied by elevation or land use. Prevalence and recovery rates did not vary by elevation from 2008 to 2009. Avian pox prevalence and proportion of recovered individuals in undeveloped and urban areas did not change from 2008 to 2009. In agricultural areas, avian pox prevalence increased 8-fold (from 2% to 17% of 234 individuals sampled) and proportion of recovered individuals increased (11% to 19%) from 2008 to 2009. These results suggest high disease-related mortality. Variation in immune function across human land-use types correlated with variation in both increased prevalence and susceptibility, which indicates changes in innate immune function may underlie changes in disease susceptibility. Our results suggest anthropogenic disturbance, in particular agricultural practices, may underlie immunological changes in host species that themselves contribute to pathogen emergence.

Detection of persistent west nile virus RNA in experimentally and naturally infected avian hosts.

To determine whether West Nile virus (WNV) persistent infection in avian hosts may potentially serve as an overwintering mechanism, House Sparrows and House Finches, experimentally and naturally infected with several strains of WNV, and two naturally infected Western Scrub-Jays were held in mosquito-proof outdoor aviaries from 2007-March 2008. Overall, 94% (n = 36) of House Sparrows, 100% (n = 14) of House Finches and 2 Western Scrub-Jays remained WNV antibody positive. When combined by species, 37% of the House Sparrows, 50% of the House Finches, and 2 Western Scrub-Jays were WNV RNA positive at necropsy, up to 36 weeks post-infection. Infectious WNV was not detected. Our study supports the hypothesis that some avian hosts support the long-term persistence of WNV RNA, but it remains unresolved whether these infections relapse to restart an avian-arthropod transmission cycle and thereby serve as an overwintering mechanism for WNV.