Comparative clinico-pathological assessment of velogenic (sub-genotype VIIi) and mesogenic (sub-genotype VIm) Avian avulavirus 1 in chickens and pigeons.

Newcastle disease (ND), caused by virulent Avian avulavirus 1 (AAvV 1), affects a wide range of avian species worldwide. Recently, several AAvVs of diverse genotypes have emerged with varying genomic and residue substitutions, and subsequent clinical impact on susceptible avian species. We assessed the clinico-pathological influence of two different AAvV 1 pathotypes [wild bird originated-velogenic strain (sub-genotype VIIi, MF437287) and feral pigeon originated-mesogenic strain (sub-genotype VIm, KU885949)] in commercial broiler chickens and pigeons. The velogenic strain caused 100% mortality in both avian species while the mesogenic strain caused 0% and 30% mortality in chickens and pigeons, respectively. Both strains showed tissue tropism for multiple tissues including visceral organs; however, minor variances were observed according to host and pathotype. The observed gross and microscopic lesions were typical of AAvV 1 infection. Utilizing oropharyngeal and cloacal swabs, a comparable pattern of viral shedding was observed for both strains from each of the infected individuals of both avian species. The study concludes a varying susceptibility of chickens and pigeons to different wild bird-originated AAvV 1 pathotypes and, therefore, suggests continuous monitoring and surveillance of currently prevailing strains for effective control of the disease worldwide, particularly in disease-endemic countries.

Protective Measures for Humans against Avian Influenza A(H5N8) Outbreaks in 22 European Union/European Economic Area Countries and Israel, 2016-17.

We sought to better understand national approaches for managing potential human health risks during outbreaks of infection with avian influenza A(H5N8) virus during 2016-17. Twenty-three countries in the Union/European Economic Area and Israel participated in this study. Risk to the general public was assessed as low in 18 countries and medium in 1 country. Of 524 exposed persons identified, 274 were passively monitored and 250 were actively monitored. Of 29 persons tested, all were negative for H5N8 virus. Vaccination and antiviral drug recommendations varied across countries. A high level of personal protection was recommended although a low risk was assessed. No transmission of this virus to humans was identified.

Recommendations for a standardized avian coronavirus (AvCoV) nomenclature: outcome from discussions within the framework of the European Union COST Action FA1207: "towards control of avian coronaviruses: strategies for vaccination, diagnosis and surveillance".

Viruses within the Coronaviridae family show variations within their genome sequences, especially within the major structural protein the Spike (S) glycoprotein gene. Therefore, many different antigenic forms, serotypes or variant strains of avian coronaviruses (AvCoV) exist worldwide. Only a few of them, the so called protectotypes, cross protect against different serotypes. New serotypes arise by recombination or spontaneous mutations. From time to time, antigenic virus variants appear, which differ significantly from known serotypes. The result of this variability is an inconsistent nomenclature and classification of virus strains. Furthermore, there are currently no standard classification methods defined. Within the framework of the COST Action FA1207 "Towards control of avian coronaviruses: strategies for diagnosis, surveillance and vaccination" (working groups "Molecular virology" and "Epidemiology"), we aimed at defining and developing a unified and internationally standardized nomenclature and classification of AvCoVs. We recommend the use of "CoV Genus/AvCov/host/country/specimen id/year" to refer to AvCoV strains.

Recommendations for a Standardized Avian Coronavirus (AvCoV) Nomenclature: Outcome from Discussions Within the Framework of the European Union COST Action FA1207: "Towards Control of Avian Coronaviruses: Strategies for Vaccination, Diagnosis and Surveillance".

Viruses within the Coronaviridae family show variations within their genome sequences, especially within the major structural protein, the Spike (S) glycoprotein gene. Therefore, many different antigenic forms, serotypes, or variant strains of avian coronaviruses (AvCoV) exist worldwide. Only a few of them, the so called protectotypes, cross protect against different serotypes. New serotypes arise by recombination or spontaneous mutations. From time to time, antigenic virus variants appear which differ significantly from known serotypes. The result of this variability is an inconsistent nomenclature and classification of virus strains. Furthermore, there are currently no standard classification methods defined. Within the framework of the COST Action FA1207 "Towards control of avian coronaviruses: strategies for diagnosis, surveillance, and vaccination" (working groups "Molecular virology" and "Epidemiology"), we aimed at defining and developing a unified and internationally standardized nomenclature and classification of AvCoVs. We recommend the use of "CoV Genus/AvCov/host/country/specimen id/year" to refer to AvCoV strains.

Genetic characterization and pathogenicity assessment of Newcastle disease virus isolated from wild peacock.

The continued spread and occurrence of Newcastle disease virus (NDV) has posed potential threat to domestic poultry industry around the globe. Mainly, wild avian species has always been implicated for the natural reservoir for virus and spread of the disease. In the present study, we report the isolation of Newcastle disease virus (NDV/Peacock/India/2012) in necropsy brain tissue sample of wild peacock from North India. Complete genome of the virus was found to be 15,186 nucleotides (nts) with six genes in order of 3'-N-P-M-F-HN-L-5', which was limited by 55-nts leader region at the 3' end and a 114-nts trailer sequence at 5' end. Sequence analysis of fusion protein revealed the dibasic amino acid cleavage site (112)R-R-Q-K-R-F(117), a characteristic motif of virulent virus. Phylogenetic analysis placed the isolate in genotype II of Newcastle disease virus showing the lowest mean percent divergence (6 %) with other genotype II counterparts. The isolate was characterized as mesogenic (intermediate pathotype) based on the mean death time (63 h) in embryonated chicken eggs and the intra-cerebral pathogenicity index (1.40) in day-old chicks. The report emphasizes the dynamic ecology of NDV strains circulating in a wild avian host during the outbreak of 2012 in North India. Further the genotypic and pathotypical characterizations of the isolate could help in development of homologous vaccine against NDV strain circulating in avian population.

Rapid genotyping of beak and feather disease virus using high-resolution DNA melt curve analysis.

Beak and feather disease virus (BFDV) is a significant pathogen both for wild and captive psittacine birds globally. Genotypic differentiation of BFDV isolates is crucial to establish effective control strategies for the conservation of endangered species and epidemiological investigations of disease outbreaks. The technique developed in this study is a simple, rapid and inexpensive genotyping method for BFDV using PCR and subsequent high-resolution melt (HRM) curve analysis. This was achieved using PCR amplification of the conserved Rep gene in the presence of a fluorescent DNA intercalating dye (SYTO9). HRM curve analysis of the resultant amplicon could readily differentiate between reference strain (92-SR14) and 18 other BFDV isolates used in this study. Analysis of the nucleotide sequences of the amplicon from each isolate revealed that each melt curve profile was related to a unique DNA sequence. The potential of the PCR-HRM curve analysis to differentiate inter-host genetic variation among critically endangered orange-bellied parrots, lorikeets and cockatoos was also evaluated. Phylogenetic tree topology based on partial Rep gene sequences used in this study showed that BFDV Rep gene sequence patterns were correlated with the results of HRM curve analysis. The results presented in this study indicate that this technique could be used in both clinical research and differentiation of BFDV isolates in a fraction of time without further nucleotide sequencing and provides a novel approach for the genetic screening of BFDV in clinical virology laboratories.

The impact of West Nile virus on the abundance of selected North American birds.

BACKGROUND: The emergence of West Nile virus (WNV) in North America has been associated with high mortality in the native avifauna and has raised concerns about the long-term impact of WNV on bird populations. Here, we present results from a longitudinal analysis of annual counts of six bird species, using North American Breeding Bird Survey data from ten states (1994 to 2010). We fit overdispersed Poisson models to annual counts. Counts from successive years were linked by an autoregressive process that depended on WNV transmission intensity (annual West Nile neuroinvasive disease reports) and was adjusted by El Niño Southern Oscillation events. These models were fit using a Markov chain Monte Carlo algorithm. RESULTS: Model fit was mostly excellent, especially for American Crows, for which our models explained between 26% and 81% of the observed variance. The impact of WNV on bird populations was quantitatively evaluated by contrasting hypothetical count trajectories (omission of WNV) with observed counts. Populations of American crows were most consistently affected with a substantial cumulative impact in six of ten states. The largest negative impact, almost 60%, was found in Illinois. A regionally substantial decline was also seen for American Robins and House Sparrows, while the other species appeared unaffected. CONCLUSIONS: Our results confirm findings from previous studies that single out American Crows as the species most vulnerable to WNV infection. We discuss strengths and limitations of this and other methods for quantifying the impact of WNV on bird populations.

Assessment of a novel real-time pan-flavivirus RT-polymerase chain reaction.

Outbreaks of West Nile virus (WNV) have occurred intermittently in regions around the Mediterranean coast, and the virus may have become established in Northern Italy and Romania, with reported intermittent outbreaks in Spain, Hungary, and France. WNV has also spread rapidly throughout the Americas since its introduction into New York in 1999. This capacity to emerge in new geographical locations and to spread rapidly together with the current increase in incidence of other flaviviruses such as tick-borne encephalitis virus, dengue virus, and Usutu virus has prompted us to design a novel pan-flavivirus RT-polymerase chain reaction for the purpose of surveillance for a range of flaviviruses. The assay utilizes degenerate primers targeting the flavivirus NS5 gene (RNA-dependent RNA polymerase) and detects a range of flaviviruses, including WNV. A small panel of WNV bird samples obtained from the United States has been shown to be detected using this assay. The amplicon generated is of sufficient size to provide sequence data to confirm the identity of the virus detected and undertake limited phylogenetic analysis. Testing using this assay has shown its ability to detect a range of tick-borne flaviviruses, particularly louping ill virus that is endemic in areas of the United Kingdom. The assay has been used to survey 160 bird samples and 1000 mosquito samples from the United Kingdom and found no evidence for WNV.

Antibodies to flaviviruses in wild ducks captured in Hokkaido, Japan: risk assessment of invasive flaviviruses.

Recently, the distribution of Japanese encephalitis virus (JEV) and West Nile virus (WNV) has expanded into new territories. The invasion of WNV into Japan is of great concern. The migration of birds is suggested to be involved in the expanded distribution of these flaviviruses. In this study, 92 wild ducks--20 Anas poecilorhyncha (migratory breeders), 50 Anas platyrhynchos (undetermined), 16 Anas acuta (winter visitors), and 6 Anas penelope (winter visitors)--were captured in autumn of 2005 and 2006, in the central part of Hokkaido, a low JEV activity area. A seroepidemiologic analysis of flavivirus infections was conducted with 90% and 50% focus reduction neutralization tests (FRNT(90) and FRNT(50)). Of the 92 serum samples, 1 (1.1%) and 5 (5.4%) tested positive for WNV-specific and JEV-specific antibodies, respectively, in the FRNT(90), and 61 (66.3%) and 79 (85.9%) tested positive for WNV and JEV, respectively, in the FRNT(50). These results indicate that wild ducks in this study had been exposed to flaviviruses. The results together with the recognized distribution of flaviviruses and migratory routes of individual duck species strongly suggested that the birds captured in this study had been exposed to flaviviruses, including WNV, on the flyway, not in Hokkaido.

Assessment of recombinant beak and feather disease virus capsid protein as a vaccine for psittacine beak and feather disease.

Beak and feather disease virus (BFDV) is a significant pathogen of wild Australasian and African psittacine birds. We assessed the immunogenicity of recombinant BFDV capsid (recBFDVcap) to protect against the development of psittacine beak and feather disease (PBFD). Long-billed corellas (Cacatua tenuirostris) (n=13) received (by injection) 1 ml vaccine containing 10 microg recBFDVcap on day 0 and 0.4 ml vaccine containing 66.8 microg recBFDVcap on day 11. All vaccinated corellas and five non-vaccinated control corellas were given 0.4 ml BFDV suspension [titre=log(2) 12 haemagglutination units (HAU) 50 microl(-1)] intramuscularly and 0.1 ml orally 16 days after booster vaccination. Blood was collected during the vaccination period and blood and feathers were collected after BFDV administration. Testing of blood samples included BFDV DNA detection by PCR and quantitative PCR (qPCR) as well as antibody detection by haemagglutination inhibition (HI) and on feather samples, BFDV DNA and antigen was detected by haemagglutination (HA) and qPCR. Four of 97 blood samples collected from vaccinated birds after virus challenge tested positive by PCR, whereas 17 of 35 samples taken from non-vaccinated control corellas tested positive. Vaccinated birds did not develop feather lesions, had only transient PCR-detectable viraemia and had no evidence of persistent infection 270 days post-challenge using PCR, histopathology and immunohistochemistry. Non-vaccinated control corellas developed transient feather lesions and had PCR, HI and HA test results consistent with PBFD. They were BFDV PCR-positive for up to 41 days post-challenge and qPCR demonstrated reduced virus replication in vaccinated birds compared with non-vaccinated control birds.

Evaluation of antigen-capture ELISA and immunohistochemical methods for avian surveillance of West Nile virus.

Accurate detection of West Nile virus (WNV) in corvids is essential for monitoring the spread of virus during the mosquito season. Viremia in corvids is very high, with titers approaching 10(8) viral particles/ml. In the presence of such marked viremia, the sensitivity of real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis is unnecessary, and more cost-effective methods should be assessed. To this end, antigen-capture ELISA (ACE) and immunohistochemical (IHC) assays were evaluated. Skin, cloacal swab specimens, and feathers from corvids were tested by use of ACE, and results were compared with results obtained from use of real-time RT-PCR analysis. Of the 3 sample types, skin gave the best sensitivity (98%) and specificity (100%). Skin, brain, kidney, and spleen from corvids were analyzed by IHC, and results were compared with real-time RT-PCR results. Kidney and spleen were more often positive by use of IHC than were brain and skin tissue; however, IHC did not perform as well as ACE in the identification of virus-positive birds. Results of this study support the use of a skin sample in an ACE format as an effective surveillance method for corvids.