Presence of Vaccine-Derived Newcastle Disease Viruses in Wild Birds

Spillover of Newcastle disease virus to Himalayan Griffon vulture: a possible food-based transmission

The Newcastle disease virus (NDV) affects wild and domesticated bird species, including commercial poultry. Although the diversity of NDV in domestic chickens is well documented, limited information is available about Newcastle disease (ND) outbreaks in other bird species. We report an annotated sequence of NDV/Vulture/Borjuri/01/22, an avirulent strain of NDV reported from Borjuri, Northeast India, in Himalayan Griffon vulture. The complete genome is 15,186 bases long with a fusion protein (F) cleavage site 112GRQGR↓L117. The phylogenetic analysis based on the F protein gene and the whole genome sequence revealed that the isolate from the vulture belongs to genotype II, sharing significant homology with vaccine strain LaSota. The study highlights the possible spillover of the virus from domestic to wild species through the food chain.

Connectivity at the human-wildlife interface: starling movements relate to carriage of E. coli

Synanthropic bird species in human, poultry or livestock environments can increase the spread of pathogens and antibiotic-resistant bacteria between wild and domestic animals. We present the first telemetry-based spatial networks for a small songbird. We quantified landscape connectivity exerted by spotless starling movements, and aimed to determine if connectivity patterns were related to carriage of potential pathogens. We captured 28 starlings on a partridge farm in 2020 and tested them for Avian influenza virus, West Nile virus WNV, Avian orthoavulavirus 1, Coronavirus, Salmonella spp. and Escherichia coli. We did not detect any viruses or Salmonella, but one individual had antibodies against WNV or cross-reacting Flaviviruses. We found E. coli in 61 % (17 of 28) of starlings, 76 % (13 of 17) of which were resistant to gentamicin, 12 % (2 of 17) to cefotaxime/enrofloxacin and 6 % (1 of 17) were phenotypic extended spectrum beta-lactamase (ESBL) carriers. We GPS-tracked 17 starlings and constructed spatial networks showing how their movements (i.e. links) connect different farms with nearby urban and natural habitats (i.e. nodes with different attributes). Using E. coli carriage as a proxy for acquisition/dispersal of bacteria, we found differences across spatial networks constructed for E. coli positive (n = 7) and E. coli negative (n = 9) starlings. We used Exponential Random Graph Models to reveal significant differences between networks. In particular, an urban roost was more connected to other sites by movements of E. coli positive than by movements of E. coli negative starlings. Furthermore, an open pine forest used mainly for roosting was more connected to other sites by movements of E. coli negative than by movements of E. coli positive starlings. Using E. coli as a proxy for a potential pathogen carried by starlings, we reveal the pathways of spread that starlings could provide between farms, urban and natural habitats.

Detection of Avian Orthoavulavirus-1 genotypes VI.2.1 and VII.1.1 with neuro-viscerotropic tropism in some backyard pigeons (Columbidae) in Eastern Saudi Arabia

Introduction

Avian orthoavulavirus-1 (AOAV1) has a wide host range, including domestic and wild birds. The present study aimed to identify the currently circulating AOAV1 strains from some outbreaks in some backyard pigeons in the eastern region of Saudi Arabia (ERSA).

Methods

Tracheal/cloacal swabs and tissue specimens were collected from eight backyards in Al-Ahsa, ERSA, between January 2021 and March 2023. Samples were tested for the presence of AOAV1 using commercial real-time RT-PCR. Part of the fusion gene was also amplified by gel-based RT-PCR, and the obtained amplicons were sequenced.

Results and discussion

AOAV1 was detected in samples from the eight flocks. The retrieved sequences from samples of 6/8 pigeon backyards are reported. Phylogenetic analysis based on the obtained sequences from these backyard pigeons showed the segregation of the obtained sequences in AOAV1 genotypes VI.2.1 and VII.1.1. Clinically, nervous manifestations were dominant in pigeons infected with both genotypes. Respiratory manifestations and significantly higher overall mortality rate were induced by genotype VI.2.1. The deduced amino acid sequences of the fusion protein cleavage site (FPCS) showed that all the detected isolates belong to velogenic strains. Differences in clinical profiles induced by the natural infection of pigeons with AOAV1 genotypes VI.2.1 and VII.1.1 were reported. The present findings highlight the potential roles of some backyard pigeons in the long-distance spread and cross-species transmission of the reported AOAVI genotypes. Further research is required to perform biotyping and pathotyping of the reported strains.

Circulation of Antibiotic-Resistant Escherichia coli in Wild and Domestic Waterfowl in Ukraine

Background: Antibiotic resistance is becoming an increasingly urgent problem for human and animal health due to the widespread use of antibiotics in medicine, veterinary medicine, and agriculture. At the same time, the natural reservoirs of antibiotic-resistant pathogens remain unclear. Wild birds may play a role in this due to their biology. Escherichia coli is a representative indicator pathogen for antibiotic resistance studies. Materials and Methods: In 2020-2021, sampling of feces and cloacal swabs from six species of wild waterfowl (Eurasian wigeon Anas penelope, Eurasian teal Anas crecca, white-fronted goose Anser albifrons, red-breasted goose Rufibrenta ruficollis, graylag goose Anser anser, shelduck Tadorna tadorna) and from two species of domestic waterfowl (ducks and geese) was conducted in the Kherson, Zaporizhzhia, Odesa, Kharkiv, and Cherkasy regions of Ukraine. Biological material was collected, stored, and transported in cryotubes with transport medium (brain heart infusion broth [BHIB] with the addition of 15% glycerol) in liquid nitrogen. Bacteriological studies were carried out according to standard methods for the isolation and identification of microorganisms. Drug resistance of E. coli was carried out by a standard disk diffusion method. Results: Bacteria representing six families (Enterobacteriaceae, Yersiniaceae, Morganellaceae, Bacillaceae, Pseudomonadaceae, Staphylococcaceae) were isolated from clinically healthy wild birds (wigeon, Eurasian teal, white-fronted goose, red-breasted goose, mallard, graylag goose, shelduck) in the southern regions of Ukraine with isolation rates ranging from 26.7% to 100%. A total of 19 E. coli isolates were cultured from 111 samples from wild birds, and 30 isolates of E. coli were cultured from 32 poultry samples. E. coli was isolated from birds of all species. The prevalence of E. coli ranged from 5.0% to 33.3% in wild waterfowl and from 90.9% to 100% in domestic waterfowl. The prevalence of multidrug-resistant (MDR) E. coli ranged from 10.0% to 31.8% in wild and domestic waterfowl: 3 of 15 (20%) specimens from wild mallard were MDR in the Kherson region, as well as 7 of 22 domestic ducks (31.8%) and 1 of 10 geese (10%) in the Kharkiv and Cherkasy regions. Isolates from wild birds were the most resistant to ampicillin (AMP), amoxiclav (AMC), amoxicillin (AMX), doxycycline (DO), and chloramphenicol (C). Isolates from poultry were resistant to ampicillin, amoxiclav, doxycycline, amoxicillin, chloramphenicol, and enrofloxacin (EX). Most of the other E. coli isolates from wild waterfowl were classified as non-multidrug-resistant (non-MDR) forms. Analysis of antibiotic sensitivity phenotypes showed that only four antibiotic-resistant phenotypes were detected among non-MDR bacteria, whereas among the MDR bacteria, two antibiotic-resistant phenotypes were detected in mallards and six in domestic waterfowl. Conclusion: The results of this study showed that wild waterfowl in Ukraine, which live in natural conditions and do not receive any antimicrobial drugs, are carriers of E. coli that are resistant to a number of antibiotics that are actively used in industrial poultry.

Virulent Newcastle disease virus genotypes V.3, VII.2, and XIII.1.1 and their coinfections with infectious bronchitis viruses and other avian pathogens in backyard chickens in Tanzania

Oropharyngeal (OP) and cloacal (CL) swabs from 2049 adult backyard chickens collected at 12 live bird markets, two each in Arusha, Dar es Salaam, Iringa, Mbeya, Morogoro and Tanga regions of Tanzania were screened for Newcastle disease virus (NDV) using reverse transcription real-time PCR (rRT-PCR). The virus was confirmed in 25.23% of the birds (n = 517; rRT-PCR CT ≤ 30), with the highest positivity rates observed in birds from Dar es Salaam region with higher prevalence during the dry season (September-November 2018) compared to the rainy season (January and April-May 2019). Next-generation sequencing of OP/CL samples of 20 out of 32 birds that had high amounts of viral RNAs (CT ≤ 25) resulted in the assembly of 18 complete and two partial genome sequences (15,192 bp and 15,045-15,190 bp in length, respectively) of NDV sub-genotypes V.3, VII.2 and XIII.1.1 (n = 1, 13 and 4 strains, respectively). Two birds had mixed NDV infections (V.3/VII.2 and VII.2/XIII.1.1), and nine were coinfected with viruses of families Astroviridae, Coronaviridae, Orthomyxoviridae, Picornaviridae, Pneumoviridae, and Reoviridae. Of the coinfecting viruses, complete genome sequences of two avastroviruses (a recombinant chicken astrovirus antigenic group-Aii and avian nephritis virus genogroup-5) and two infectious bronchitis viruses (a turkey coronavirus-like recombinant and a GI-19 virus) were determined. The fusion (F) protein F1/F2 cleavage sites of the Tanzanian NDVs have the consensus motifs 112 RRRKR↓F 117 (VII.2 strains) and 112 RRQKR↓F 117 (V.3 and XIII.1.1 strains) consistent with virulent virus; virulence was confirmed by intracerebral pathogenicity index scores of 1.66-1.88 in 1-day-old chicks using nine of the 20 isolates. Phylogenetically, the complete F-gene and full genome sequences regionally cluster the Tanzanian NDVs with, but distinctly from, other strains previously reported in eastern and southern African countries. These data contribute to the understanding of NDV epidemiology in Tanzania and the region.

Newcastle disease virus (NDV) recombinant expressing Marek's disease virus (MDV) glycoprotein B significantly protects chickens against MDV and NDV challenges

Marek's disease (MD) is a highly contagious viral neoplastic disease of chickens caused by Marek's disease virus (MDV), resulting in significant economic losses to the poultry industry worldwide. The commonly used live and/or vectored MDV vaccines are expensive to produce and difficult to handle due to the requirement of liquid nitrogen for manufacturing and delivering frozen infected cells that are viable. In this study, we aimed to develop a Newcastle disease virus (NDV) vectored MDV vaccine that can be lyophilized, stored, and transported at 4 °C. Four NDV LaSota (LS) vaccine strain-based recombinant viruses expressing MDV glycoproteins gB, gC, gE, or gI were generated using reverse genetics technology. The biological assessments showed that these recombinant viruses were slightly attenuated in vivo yet retained similar growth kinetics and virus titers in vitro compared to the parental LaSota virus. Vaccination of leghorn chickens (Lines 15I5x71 F1 cross) with these recombinant viruses via intranasal and intraocular routes conferred different levels of protection against virulent MDV challenge. The recombinant expressing the MDV gB protein, rLS/MDV-gB, protected vaccinated birds significantly against MDV-induced tumor formation when challenged at 14 days post-vaccination (DPV) but moderately at 5 DPV. Whereas the other three recombinants provided little protection against the MDV challenge. All four recombinants conferred complete protection against the velogenic NDV challenge. These results demonstrated that the rLS/MDV-gB virus is a safe and efficacious dual vaccine candidate that can be lyophilized and potentially mass-administered via aerosol or drinking water to large chicken populations at a meager cost.

Environmental spillover of emerging viruses: Is it true?

The concept of environmental "spillover" of pathogens to humans is widely used in the scientific literature about emerging diseases with the idea that it is scientifically proven. However, the exact characterization of the mechanism of spillover is simply lacking. A systematic review retrieved 688 articles using this term. The systematic analysis revealed an irreducible polysemy covering ten different definitions. It also demonstrated the absence of explicit definition in most of the articles, and even antinomies. A modeling analysis of the various processes described by these ten definitions showed that none of them corresponded to the complete trajectory leading to the emergence of a disease. There is no article demonstrating a mechanism of spillover. There are only ten articles proposing ideas on how a putative spillover could work but they merely are intellectual constructions. All other articles only reuse the term with no demonstration. It is essential to understand that since there is no scientific concept behind the "spillover", it might be dangerous to base public health and public protection against future pandemics on it.

Niclosamide inhibits Newcastle disease virus replication in chickens by perturbing the cellular glycolysis

Newcastle disease virus (NDV), a member of Paramyxoviridae family, is one of the most important pathogens in poultry. To ensure optimal environments for their replication and spread, viruses rely largely on host cellular metabolism. In the present study, we evaluated the small drug molecule niclosamide for its anti-NDV activity. Our study has shown that a sublethal dose of 1 μM niclosamide could drastically reduce NDV replication. The results showed that niclosamide has antiviral activity against NDV infection during in vitro, in ovo and in vivo assays. Pharmacologically inhibiting the glycolytic pathway remarkably reduced NDV RNA synthesis and infectious virion production. Our results suggest that the effect of niclosamide on cellular glycolysis could be the possible reason for the specific anti-NDV effect. This study could help us understand antiviral strategies against similar pathogens and may lead to novel therapeutic approaches through targeted inhibition of specific cellular metabolic pathways.

Genetic diversity of Newcastle disease viruses circulating in wild and synanthropic birds in Ukraine between 2006 and 2015

Newcastle disease virus (NDV) infects a wide range of bird species worldwide and is of importance to the poultry industry. Although certain virus genotypes are clearly associated with wild bird species, the role of those species in the movement of viruses and the migratory routes they follow is still unclear. In this study, we performed a phylogenetic analysis of nineteen NDV sequences that were identified among 21,924 samples collected from wild and synanthropic birds from different regions of Ukraine from 2006 to 2015 and compared them with isolates from other continents. In synanthropic birds, NDV strains of genotype II, VI, VII, and XXI of class II were detected. The fusion gene sequences of these strains were similar to strains detected in birds from different geographical regions of Europe and Asia. However, it is noteworthy to mention the isolation of vaccine viruses from synanthropic birds, suggesting the possibility of their role in viral transmission from vaccinated poultry to wild birds, which may lead to the further spreading of vaccine viruses into other regions during wild bird migration. Moreover, here we present the first publicly available complete NDV F gene from a crow (genus Corvus). Additionally, our phylogenetic results indicated a possible connection of Ukrainian NDV isolates with genotype XXI strains circulating in Kazakhstan. Among strains from wild birds, NDVs of genotype 1 of class I and genotype I of class II were detected. The phylogenetic analysis highlighted the possible exchange of these NDV strains between wild waterfowl from the Azov-Black Sea region of Ukraine and waterfowl from different continents, including Europe, Asia, and Africa.

Risky business in Georgia's wild birds: Contact rates between wild birds and backyard chickens is influenced by supplemental feed

Backyard chickens are increasingly popular, and their husbandry varies widely. How backyard chickens are housed may influence the accessibility of chicken feed and water to wild birds, and thus, the contact rates between both groups. Increased contacts have implications for pathogen transmission; for instance, Newcastle disease virus or avian influenza virus may be transmitted to and from backyard chickens from contaminated water or feed. Given this potentially increased pathogen risk to wild birds and backyard chickens, we examined which wild bird species are likely to encounter backyard chickens and their resources. We performed a supplemental feeding experiment followed by observations at three sites associated with backyard chickens in North Georgia, USA. At each site, we identified the species of wild birds that: (a) shared habitat with the chickens, (b) had a higher frequency of detection relative to other species and (c) encountered the coops. We identified 14 wild bird species that entered the coops to consume supplemental feed and were considered high-risk for pathogen transmission. Our results provide evidence that contact between wild birds and backyard chickens is frequent and more common than previously believed, which has crucial epidemiological implications for wildlife managers and backyard chicken owners.

Peptide Multimerization as Leads for Therapeutic Development

Multimerization of peptide structures has been a logical evolution in their development as potential therapeutic molecules. The multivalent properties of these assemblies have attracted much attention from researchers in the past and the development of more complex branching dendrimeric structures, with a wide array of biocompatible building blocks is revealing previously unseen properties and activities. These branching multimer and dendrimer structures can induce greater effect on cellular targets than monomeric forms and act as potent antimicrobials, potential vaccine alternatives and promising candidates in biomedical imaging and drug delivery applications. This review aims to outline the chemical synthetic innovations for the development of these highly complex structures and highlight the extensive capabilities of these molecules to rival those of natural biomolecules.

Survey on the Presence of Viruses of Economic and Zoonotic Importance in Avifauna in Northern Italy

Wild birds play an important role in the circulation and spread of pathogens that are potentially zoonotic or of high economic impact on zootechnical production. They include, for example, West Nile virus (WNV), Usutu virus (USUV), avian influenza virus (AIV), and Newcastle disease virus (NDV), which, despite having mostly an asymptomatic course in wild birds, have a strong impact on public health and zootechnical production. This study investigated the presence of these viruses in several wild bird species from North Italy during the biennium 2019-2020. Wild birds derived from 76 different species belonging to 20 orders. Out of 679 birds, 27 were positive for WNV (lineage 2) with a prevalence of 4%; all birds were negative for USUV; one gull was positive for H13N6 influenza virus, and 12 samples were positive for NDV with a prevalence of 2%. Despite the low prevalence observed, the analyses performed on these species provide further data, allowing a better understanding of the diffusion and evolution of diseases of both economic and zoonotic importance.

Epidemiology of Newcastle disease in Africa with emphasis on Côte d'Ivoire: A review

For decades, Newcastle disease (ND) has long been recognized as a frontline viral disease that constrains poultry production throughout Africa. The need to update on the epidemiology of the disease is rife, due to the increasing importance of poultry farming. In addition, poultry farming serves as the top animal food source globally. However, in Africa, the greater population of poultry is reared under traditional and conventional husbandry methods. This hugely impedes the ability of management practices to be correctly embraced in limiting or excluding viral pathogens in the poultry production chain. We conducted this review to consolidate recently published studies in the field and provide an overview of the disease. We reviewed original studies conducted on ND, the current taxonomic classification of the virus, clinical signs of the disease, and laboratory diagnostic methods available for virus detection and typing. This review additionally examined the control methods currently used, including available or circulating vaccines, vaccinations, recent vaccine findings, and the main variants of the virus present in West Africa. More specifically, we present a review of the current status and available information on the disease in Côte d’Ivoire. The lack of up-to-date and relevant information on the current prevalence, socio-economic impact, and ethnoveterinary medicine used against ND is probably the main limitation for appropriate and effective decision-making for better control of this disease in Côte d’Ivoire.

Virulence during Newcastle Disease Viruses Cross Species Adaptation

The hypothesis that host adaptation in virulent Newcastle disease viruses (NDV) has been accompanied by virulence modulation is reviewed here. Historical records, experimental data, and phylogenetic analyses from available GenBank sequences suggest that currently circulating NDVs emerged in the 1920-1940's from low virulence viruses by mutation at the fusion protein cleavage site. These viruses later gave rise to multiple virulent genotypes by modulating virulence in opposite directions. Phylogenetic and pathotyping studies demonstrate that older virulent NDVs further evolved into chicken-adapted genotypes by increasing virulence (velogenic-viscerotropic pathotypes with intracerebral pathogenicity indexes [ICPIs] of 1.6 to 2), or into cormorant-adapted NDVs by moderating virulence (velogenic-neurotropic pathotypes with ICPIs of 1.4 to 1.6), or into pigeon-adapted viruses by further attenuating virulence (mesogenic pathotypes with ICPIs of 0.9 to 1.4). Pathogenesis and transmission experiments on adult chickens demonstrate that chicken-adapted velogenic-viscerotropic viruses are more capable of causing disease than older velogenic-neurotropic viruses. Currently circulating velogenic-viscerotropic viruses are also more capable of replicating and of being transmitted in naïve chickens than viruses from cormorants and pigeons. These evolutionary virulence changes are consistent with theories that predict that virulence may evolve in many directions in order to achieve maximum fitness, as determined by genetic and ecologic constraints.

Comparative safety and efficacy of two bivalent vaccines containing Newcastle disease LaSota and avian influenza H9N2 Sidrap isolate formulated with different oil adjuvants

Background and Aim:

Newcastle disease (ND) and avian influenza (AI) are two devastating diseases of poultry, which cause great economic losses to the poultry industry and disrupt food security in our country. The use of ND-AI inactive bivalent vaccine is very effective and economical to prevent and control ND and AI disease. Bivalent ND LaSota-AI H9N2 vaccine is not yet available in Indonesia. The inactivated vaccines used in poultry industry often require oil adjuvant to elicit a sufficient immune response. This study aimed to develop the bivalent inactive vaccines containing ND LaSota and AI H9N2 Sidrap isolate which are local isolates as poultry vaccine candidates, and formulated with two different commercial adjuvants, then compared.

Materials and Methods:

Two vaccines bivalent were prepared by emulsifying inactivated Newcastle disease virus (LaSota strain) and AI H9N2 Sidrap isolate viruses with Marcol white mineral oil and Montanide ISA70 adjuvants. Both of bivalent vaccines were tested for safety (physical and histopathological at the injection site) and efficacy in specific-pathogen-free chickens. Parameters used for the evaluation of the efficacy were immunogenicity by hemagglutination inhibition and protection percentage.

Results:

Both bivalent vaccines are safe to use. Post-vaccination (PV) immune response was observed using a hemagglutination inhibition test at 2, 3, 4, 5, 6, 7, and 8 weeks of PV. The bivalent vaccine B gives a better immune response to ND at 2, 3, and 4 weeks of PV (p<0.05) compared to the bivalent vaccine A, but in 5, 6, 7, and 8 weeks, the PV does not show differences in the immune response. The immune response to AI H9N2 showed differences at weeks 2 and 3 PV (p<0.05) with the bivalent vaccine B indicated higher immunity. A single immunization with both bivalent vaccines induces 100% protection in chickens that have been vaccinated against the deadly challenge with the virulent ND virus.

Conclusion:

Both of bivalent vaccines are safe to use and provide good efficacy against virulent ND viruses, but bivalent vaccine B (with Montanide ISA70 adjuvant) shows better immune response than bivalent vaccine A (Marcol white mineral oil adjuvant).

Evolutionary dynamics and transmission patterns of Newcastle disease virus in China through Bayesian phylogeographical analysis

The Chinese poultry industry has experienced outbreaks of Newcastle disease (ND) dating back to the 1920s. However, the epidemic has exhibited a downtrend in recent years. In this study, both observational and genetic data [fusion (F) and haemagglutinin-neuraminidase genes (HN)] were analyzed, and phylogeographic analysis based on prevalent genotypes of Newcastle disease virus (NDV) was conducted for better understanding of the evolution and spatiotemporal dynamics of ND in China. In line with the observed trend of epidemic outbreaks, the effective population size of F and HN genes of circulating NDV is no longer growing since 2000, which is supported by 95% highest posterior diversity (HPD) intervals. Phylogeographic analysis indicated that the two eastern coastal provinces, Shandong and Jiangsu were the most relevant hubs for NDV migration, and the geographical regions with active NDV diffusion seemed to be constrained to southern and eastern China. The live poultry trade may play an important role in viral spread. Interestingly, no migration links from wild birds to poultry received Bayes factor support (BF > 3), while the migration links from poultry to wild birds accounted for 64% in all effective migrations. This may indicate that the sporadic cases of ND in wild bird likely spillover events from poultry. These findings contribute to predictive models of NDV transmission, and potentially help in the prevention of future outbreaks.

A Review of Pathogen Transmission at the Backyard Chicken-Wild Bird Interface

Habitat conversion and the expansion of domesticated, invasive species into native habitats are increasingly recognized as drivers of pathogen emergence at the agricultural-wildlife interface. Poultry agriculture is one of the largest subsets of this interface, and pathogen spillover events between backyard chickens and wild birds are becoming more commonly reported. Native wild bird species are under numerous anthropogenic pressures, but the risks of pathogen spillover from domestic chickens have been historically underappreciated as a threat to wild birds. Now that the backyard chicken industry is one of the fastest growing industries in the world, it is imperative that the principles of biosecurity, specifically bioexclusion and biocontainment, are legislated and implemented. We reviewed the literature on spillover events of pathogens historically associated with poultry into wild birds. We also reviewed the reasons for biosecurity failures in backyard flocks that lead to those spillover events and provide recommendations for current and future backyard flock owners.

Towards an understanding of the avian virome

The last two decades have seen the rise of viromics, the study of viral communities through the detection and characterization of virus genome sequences. Here we systematically review and summarize the scope and limitations of our current understanding of avian viromes, in both domesticated and wild-bird populations. We compare this viromic work to the broader literature on avian prokaryotic microbiomes, and highlight the growing importance of structured sampling and experimental design for testing explanatory hypotheses. We provide a number of recommendations for sample collection and preliminary data analysis to guide the development of avian viromics. Avian viromes have the potential to inform disease surveillance in poultry and improve our understanding of the risk of zoonotic viruses to human health.

Experimental Infection and Transmission of Newcastle Disease Vaccine Virus in Four Wild Passerines

Our prior work has shown that live poultry vaccines have been intermittently isolated from wild birds sampled during field surveillance studies for Newcastle disease virus (NDV). Thus, we experimentally investigated the susceptibility of four native agriculturally associated wild bird species to the NDV LaSota vaccine and evaluated the shedding dynamics, potential transmission from chickens, and humoral antibody responses. To test susceptibility, we inoculated wild-caught, immunologically NDV-naïve house finches (Haemorhous mexicanus; n = 16), brown-headed cowbirds (Molothrus ater; n = 9), northern cardinals (Cardinalis cardinalis; n = 6), and American goldfinches (Spinus tristis; n = 12) with 0.1 ml (10^6.7 mean embryo infectious doses [EID_50/ml]) of NDV LaSota vaccine via the oculo-nasal route. To test transmission between chickens and wild birds, adult specific-pathogen-free white leghorn chickens were inoculated similarly and cohoused in separate isolators with two to five wild birds of the species listed above. This design resulted in three treatments: wild bird direct inoculation (five groups) and wild bird exposure to one (two groups) or two inoculated chickens (six groups), respectively. Blood and oropharyngeal and cloacal swabs were collected before and after infection with the live vaccine. All wild birds that were directly inoculated with the LaSota vaccine shed virus as demonstrated by virus isolation (VI). Cardinals were the most susceptible species based on shedding viruses from 1 to 11 days postinoculation (dpi) with titers up to 10^4.9 EID₅₀/ml. Although LaSota viruses were shed by all inoculated chickens and were present in the drinking water, most noninoculated wild birds cohoused with these chickens remained uninfected for 14 days as evidenced by VI. However, one American goldfinch tested positive for vaccine transmission by VI at 7 dpi and one house finch tested positive for vaccine transmission by real-time reverse-transcription PCR at 13 dpi. Only one directly inoculated cowbird (out of three) and two cardinals (out of two) developed NDV-specific hemagglutination inhibition antibody titers of 16, 16, and 128, respectively. No clinical signs were detected in the chickens or the wild birds postinoculation.

Highly Pathogenic and Low Pathogenic Avian Influenza H5 Subtype Viruses in Wild Birds in Ukraine

There have been three waves of highly pathogenic avian influenza (HPAI) outbreaks in commercial, backyard poultry, and wild birds in Ukraine. The first (2005-2006) and second (2008) waves were caused by H5N1 HPAI virus, with 45 outbreaks among commercial poultry (chickens) and backyard fowl (chickens, ducks, and geese) in four regions of Ukraine (AR Crimea, Kherson, Odesa, and Sumy Oblast). H5N1 HPAI viruses were isolated from dead wild birds: cormorants (Phalacrocorax carbo) and great crested grebes (Podiceps cristatus) in 2006 and 2008. The third HPAI wave consisted of nine outbreaks of H5N8 HPAI in wild and domestic birds, beginning in November 2016 in the central and south regions (Kherson, Odesa, Chernivtsi, Ternopil, and Mykolaiv Oblast). H5N8 HPAI virus was detected in dead mute swans (Cygnus olor), peacocks (Pavo cristatus) (in zoo), ruddy shelducks (Tadorna ferruginea), white-fronted geese (Anser albifrons), and from environmental samples in 2016 and 2017. Wide wild bird surveillance for avian influenza (AI) virus was conducted from 2006 to 2016 in Ukraine regions suspected of being intercontinental (north-south and east-west) flyways. A total of 21 511 samples were collected from 105 species of wild birds representing 27 families and 11 orders. Ninety-five avian influenza (AI) viruses were isolated (including one H5N2 LPAI virus in 2010) from wild birds with a total of 26 antigenic hemagglutinin (HA) and neuraminidase (NA) combinations. Fifteen of 16 known avian HA subtypes were isolated. Two H5N8 HPAI viruses (2016-2017) and two H5N2 LPAI viruses (2016) were isolated from wild birds and environmental samples (fresh bird feces) during surveillance before the outbreak in poultry in 2016-2017. The Ukrainian H5N1, H5N8 HPAI, and H5N2 LPAI viruses belong to different H5 phylogenetic groups. Our results demonstrate the great diversity of AI viruses in wild birds in Ukraine, as well as the importance of this region for studying the ecology of avian influenza.

Isolation and genetic characterization of virulent strains of avian paramyxovirus-1 from multiple avian species in Azad Jammu and Kashmir 2017-2018

Despite intensive vaccination, endemicity of Avian paramyxoviruses-1 (APMV-1) is a significant problem in developing countries in Africa, Middle East, and Asia. Given the importance of APMV-1 in poultry and multiple non-poultry avian species, it is important to continue surveillance programs, routine monitoring and characterization of field isolates in the region where viruses are endemic. The purpose of this study was to pathotyped and genetically characterized 21 APMV-1s isolated from multiple avian species reared in different regions of Azad Jammu and Kashmir (AJK). Phylogenetic analysis based on complete fusion (F) gene sequences showed that 17 APMV-1 isolates obtained from commercial poultry and backyard birds belonged to sub-genotype VIIi. Though, one pigeon-origin APMV-1 isolate was clustered in sub-genotype VIg and three in recently designated new sub-genotype VIm of genotype VI. The pigeon-origin isolates had the following two motifs ¹¹³-RKKR↓F-¹¹⁷ and ¹¹³-RQRR↓F-¹¹⁷, while all other isolates had the polybasic amino acid sequence ¹¹³-RQKR↓F-¹¹⁷ at the F-cleavage site, which is characteristic of virulent APMV-1 strains. These results are consistent with the five viruses that had intracerebral pathogenicity indices (ICPIs) of between 1.50 and 1.73, corresponding to a velogenic pathotype. The APMV-1s isolated from commercial poultry and backyard birds in this study showed low nucleotide distance (0.3-0.9%) and genetically closely related (> 97%) to viruses repeatedly isolated (2011-2017) from multiple avian species in other states of Pakistan. Strengthened surveillance programs in both commercial poultry and backyard flocks are needed to better assess the commercial-backyard bird interface and form a basis for evidence-based measures to limit and prevent APMV-1 transmission.

Genetic stability of a Newcastle disease virus vectored infectious laryngotracheitis virus vaccine after serial passages in chicken embryos

Previously, we have demonstrated that the recombinant Newcastle disease virus (NDV) expressing the infectious laryngotracheitis virus (ILTV) glycoprotein D (gD) conferred protection against both virulent NDV and ILTV challenges in chickens. In this study, we evaluated the genetic stability of the recombinant vaccine after eight serial passages in embryonated chicken eggs (ECE). The vaccine master seed virus at the original egg-passage level 3 (EP3) was diluted and passaged in three separate repetitions (A, B and C) in ECE eight times (EP4 to EP11). RT-PCR analysis of the vaccine seed and egg-passaged virus stocks showed that there was no detectable insertion/deletion in the ILTV gD insert region. Next-generation sequencing analysis of the EP3 and EP11 virus stocks confirmed their genome integrity and revealed a total of thirteen single-nucleotide polymorphisms (SNPs). However, none of these SNPs were located in the ILTV gD insert or any of the known critical biological determinant positions. Virological and immunofluorescent assays provided additional evidence that the EP11 virus stocks retained their growth kinetics, low pathogenicity, and robust level of gD expression comparable to that of the vaccine master seed virus. This indicated that the SNPs were non-detrimental sporadic mutations. These results demonstrated that the insertion of ILTV gD gene into the NDV LaSota backbone did not significantly affect the genetic stability of the recombinant virus and that the rLS/ILTV-gD virus is a safe and genetically stable vaccine candidate after at least eight serial passages in ECE.

Updated unified phylogenetic classification system and revised nomenclature for Newcastle disease virus

Several Avian paramyxoviruses 1 (synonymous with Newcastle disease virus or NDV, used hereafter) classification systems have been proposed for strain identification and differentiation. These systems pioneered classification efforts; however, they were based on different approaches and lacked objective criteria for the differentiation of isolates. These differences have created discrepancies among systems, rendering discussions and comparisons across studies difficult. Although a system that used objective classification criteria was proposed by Diel and co-workers in 2012, the ample worldwide circulation and constant evolution of NDV, and utilization of only some of the criteria, led to identical naming and/or incorrect assigning of new sub/genotypes. To address these issues, an international consortium of experts was convened to undertake in-depth analyses of NDV genetic diversity. This consortium generated curated, up-to-date, complete fusion gene class I and class II datasets of all known NDV for public use, performed comprehensive phylogenetic neighbor-Joining, maximum-likelihood, Bayesian and nucleotide distance analyses, and compared these inference methods. An updated NDV classification and nomenclature system that incorporates phylogenetic topology, genetic distances, branch support, and epidemiological independence was developed. This new consensus system maintains two NDV classes and existing genotypes, identifies three new class II genotypes, and reduces the number of sub-genotypes. In order to track the ancestry of viruses, a dichotomous naming system for designating sub-genotypes was introduced. In addition, a pilot dataset and sub-trees rooting guidelines for rapid preliminary genotype identification of new isolates are provided. Guidelines for sequence dataset curation and phylogenetic inference, and a detailed comparison between the updated and previous systems are included. To increase the speed of phylogenetic inference and ensure consistency between laboratories, detailed guidelines for the use of a supercomputer are also provided. The proposed unified classification system will facilitate future studies of NDV evolution and epidemiology, and comparison of results obtained across the world.

Cellular MicroRNA Expression Profile of Chicken Macrophages Infected with Newcastle Disease Virus Vaccine Strain LaSota

Vaccines with live, low-virulence Newcastle disease virus (NDV) strains are still the most accepted prevention and control strategies for combating Newcastle disease (ND), a major viral disease that hampers the development of the poultry industry worldwide. However, the mechanism underlying vaccine-mediated innate cell immune responses remains unclear. Here, a high-throughput Illumina sequencing approach was employed to determine cellular miRNA expression profiles in chicken macrophages infected with the LaSota virus, a widely used vaccine strain for mass vaccination programs against ND in poultry. Compared to the control group, 112 and 115 differentially expressed (DE) miRNAs were identified at 24 hpi (hours post inoculation) and 48 hpi, respectively. Meanwhile, 174 DE miRNAs were identified between 24 hpi and 48 hpi. Furthermore, 12 upregulated and 6 downregulated DE miRNAs were observed in common at 24 and 48 hpi compared with 0 hpi. In addition, target prediction and functional analysis of these DE miRNAs revealed significant enrichment for several signaling pathways, especially in the immune-related genes and pathways, such as the RIG-I-like receptor signaling pathway, NOD-like receptor signaling pathway, and mitogen-activated protein kinase (MAPK) signaling pathway. Our findings not only lay the foundations for further investigating the roles and regulatory mechanisms of miRNA in vaccine-mediated innate cellular immune responses, but also extend new insights into the interactions between the host and NDV infection.

Global phylodynamic analysis of avian paramyxovirus-1 provides evidence of inter-host transmission and intercontinental spatial diffusion

BACKGROUND

Avian avulavirus (commonly known as avian paramyxovirus-1 or APMV-1) can cause disease of varying severity in both domestic and wild birds. Understanding how viruses move among hosts and geography would be useful for informing prevention and control efforts. A Bayesian statistical framework was employed to estimate the evolutionary history of 1602 complete fusion gene APMV-1 sequences collected from 1970 to 2016 in order to infer viral transmission between avian host orders and diffusion among geographic regions. Ancestral states were estimated with a non-reversible continuous-time Markov chain model, allowing transition rates between discrete states to be calculated. The evolutionary analyses were stratified by APMV-1 classes I (n = 198) and II (n = 1404), and only those sequences collected between 2006 and 2016 were allowed to contribute host and location information to the viral migration networks.

RESULTS

While the current data was unable to assess impact of host domestication status on APMV-1 diffusion, these analyses supported the sharing of APMV-1 among divergent host taxa. The highest supported transition rate for both classes existed from domestic chickens to Anseriformes (class I:6.18 transitions/year, 95% highest posterior density (HPD) 0.31-20.02, Bayes factor (BF) = 367.2; class II:2.88 transitions/year, 95%HPD 1.9-4.06, BF = 34,582.9). Further, among class II viruses, domestic chickens also acted as a source for Columbiformes (BF = 34,582.9), other Galliformes (BF = 34,582.9), and Psittaciformes (BF = 34,582.9). Columbiformes was also a highly supported source to Anseriformes (BF = 322.0) and domestic chickens (BF = 402.6). Additionally, our results provide support for the diffusion of viruses among continents and regions, but no interhemispheric viral exchange between 2006 and 2016. Among class II viruses, the highest transition rates were estimated from South Asia to the Middle East (1.21 transitions/year; 95%HPD 0.36-2.45; BF = 67,107.8), from Europe to East Asia (1.17 transitions/year; 95%HPD 0.12-2.61; BF = 436.2) and from Europe to Africa (1.06 transitions/year, 95%HPD 0.07-2.51; BF = 169.3).

CONCLUSIONS

While migration appears to occur infrequently, geographic movement may be important in determining viral diversification and population structure. In contrast, inter-order transmission of APMV-1 may occur readily, but most events are transient with few lineages persisting in novel hosts.

Genomic comparison of Newcastle disease viruses isolated in Nigeria between 2002 and 2015 reveals circulation of highly diverse genotypes and spillover into wild birds

Newcastle disease virus (NDV) has a wide avian host range and a high degree of genetic variability, and virulent strains cause Newcastle disease (ND), a worldwide concern for poultry health. Although NDV has been studied in Nigeria, genetic information about the viruses involved in the endemicity of the disease and the transmission that likely occurs at the poultry-wildlife interface is still largely incomplete. Next-generation and Sanger sequencing was performed to provide complete (n = 73) and partial genomic sequence data (n = 38) for NDV isolates collected from domestic and wild birds in Nigeria during 2002-2015, including the first complete genome sequences of genotype IV and subgenotype VIh from the African continent. Phylogenetic analysis revealed that viruses of seven different genotypes circulated in that period, demonstrating high genetic diversity of NDV for a single country. In addition, a high degree of similarity between NDV isolates from domestic and wild birds was observed, suggesting that spillovers had occurred, including to three species that had not previously been shown to be susceptible to NDV infection. Furthermore, the first spillover of a mesogenic Komarov vaccine virus is documented, suggesting a previous spillover and evolution of this virus. The similarities between viruses from poultry and multiple bird species and the lack of evidence for host adaptation in codon usage suggest that transmission of NDV between poultry and non-poultry birds occurred recently. This is especially significant when considering that some viruses were isolated from species of conservation concern. The high diversity of NDV observed in both domestic and wild birds in Nigeria emphasizes the need for active surveillance and epidemiology of NDV in all bird species.

Presence of Newcastle disease viruses of sub-genotypes Vc and VIn in backyard chickens and in apparently healthy wild birds from Mexico in 2017

Virulent Newcastle disease viruses (NDV) have been present in Mexico since 1946, and recently, multiple outbreaks have been reported in the country. Here, we characterized eleven NDV isolated from apparently healthy wild birds and backyard chickens in three different locations of Jalisco, Mexico in 2017. Total RNA from NDV was reverse-transcribed, and 1285 nucleotides, which includes 3/4 of the fusion gene, was amplified and sequenced using a long-read MinION sequencing method. The sequences were 99.99-100% identical to the corresponding region obtained using the Illumina MiSeq. Phylogenetic analysis using MinION sequences demonstrated that nine virulent NDV from wild birds belonged to sub-genotypes Vc and VIn, and two backyard chicken isolates were of sub-genotype Vc. The sub-genotype Vc viruses had nucleotide sequence identity that ranged from 97.7 to 98% to a virus of the same sub-genotype isolated from a chicken in Mexico in 2010. Three viruses from pigeons had 96.3-98.7% nucleotide identity to sub-genotype VIn pigeon viruses, commonly referred to as pigeon paramyxovirus, isolated in the USA during 2000-2016. This study demonstrates that viruses of sub-genotype Vc are still present in Mexico, and the detection of this sub-genotype in both chickens and wild birds suggests that transmission among these species may represent a biosecurity risk. This is the first detection and complete genome sequencing of genotype VI NDV from Mexico. In addition, the utilization of an optimized long-read sequencing method for rapid virulence and genotype identification using the Oxford nanopore MinION system is demonstrated.

Epidemiology, control, and prevention of Newcastle disease in endemic regions: Latin America

Newcastle disease (ND) infects wild birds and poultry species worldwide, severely impacting the economics of the poultry industry. ND is especially problematic in Latin America (Mexico, Colombia, Venezuela, and Peru) where it is either endemic or re-emerging. The disease is caused by infections with one of the different strains of virulent avian Newcastle disease virus (NDV), recently renamed Avian avulavirus 1. Here, we describe the molecular epidemiology of Latin American NDVs, current control and prevention methods, including vaccines and vaccination protocols, as well as future strategies for control of ND. Because the productive, cultural, economic, social, and ecological conditions that facilitate poultry endemicity in South America are similar to those in the developing world, most of the problems and control strategies described here are applicable to other continents.

Isolation, identification and molecular characterization of Newcastle disease viruses in vaccinated chickens from commercial farms in the Sultanate of Oman

Newcastle disease (ND) remains an important enzootic disease in chickens in several parts of the world. With the increasing reports of virulence and genetic diversity of the causative agent; Newcastle disease virus (NDV), there is a need to identify the circulating NDV in specific regions. In Oman, to this moment, such information is still lacking. The aim of this study was to isolate and characterize the NDV from ND outbreaks from commercial farms in Oman. Following suspected outbreaks of ND in three commercial farms in 2017, a total of 30 carcasses (10 from each flock) of adult chickens were subjected to necropsy for gross and histopathological examination, virus isolation and molecular methods. Specifically, haemagglutination inhibition (HI) test and reverse transcription-polymerase chain reaction (RT-PCR) assay were used for the virus detection and confirmation, respectively. Lesions were suggestive of viscerotropic velogenic form of ND based on gross and histopathological examinations. Isolation of NDV was present in 4 cases and further confirmed by RT-PCR following the target of the partial fusion protein gene of the viral genome. The sequence of the partial fusion gene was determined and phylogenetic tree was constructed based on the partial length F gene of 4 Omani isolates and 65 previously published NDVs. The findings predicted that the Omani isolates had high homology (99%) with the isolate from Pakistan belonging to genotype VII. Subsequently, the isolated pathotype was identified as the virulent NDV. This study serves as a basic work for further research on the analysis and phenotyping of NDV in the Sultanate of Oman. Improved monitoring and surveillance of the disease is important for proper preventive measures.

Diagnostic and Vaccination Approaches for Newcastle Disease Virus in Poultry: The Current and Emerging Perspectives

Newcastle disease (ND) is one of the most devastating diseases that considerably cripple the global poultry industry. Because of its enormous socioeconomic importance and potential to rapidly spread to naïve birds in the vicinity, ND is included among the list of avian diseases that must be notified to the OIE immediately upon recognition. Currently, virus isolation followed by its serological or molecular identification is regarded as the gold standard method of ND diagnosis. However, this method is generally slow and requires specialised laboratory with biosafety containment facilities, making it of little relevance under epidemic situations where rapid diagnosis is seriously needed. Thus, molecular based diagnostics have evolved to overcome some of these difficulties, but the extensive genetic diversity of the virus ensures that isolates with mutations at the primer/probe binding sites escape detection using these assays. This diagnostic dilemma leads to the emergence of cutting-edge technologies such as next-generation sequencing (NGS) which have so far proven to be promising in terms of rapid, sensitive, and accurate recognition of virulent Newcastle disease virus (NDV) isolates even in mixed infections. As regards disease control strategies, conventional ND vaccines have stood the test of time by demonstrating track record of protective efficacy in the last 60 years. However, these vaccines are unable to block the replication and shedding of most of the currently circulating phylogenetically divergent virulent NDV isolates. Hence, rationally designed vaccines targeting the prevailing genotypes, the so-called genotype-matched vaccines, are highly needed to overcome these vaccination related challenges. Among the recently evolving technologies for the development of genotype-matched vaccines, reverse genetics-based live attenuated vaccines obviously appeared to be the most promising candidates. In this review, a comprehensive description of the current and emerging trends in the detection, identification, and control of ND in poultry are provided. The strengths and weaknesses of each of those techniques are also emphasised.

Seroprevalence of Newcastle disease virus in backyard chickens and herd-level risk factors of Newcastle disease in poultry farms in Oman

Newcastle disease (ND) is an endemic disease in Oman's poultry industry and impacts negatively on food security. However, little is known regarding the potential risks of the disease in backyard poultry. The objectives of this study were to determine the seroprevalence of Newcastle disease virus (NDV) in backyard chickens and the herd-level risk factors in Oman. In total, 1383 serum samples were collected from chickens in 139 flocks from nine governorates. Information on associated risk factors was assessed using a semi-structured questionnaire. The samples were tested using commercial indirect ELISA kits.A logistic regression model was applied to assess the associated risk factors. The bird and flock-level NDV seroprevalence was 33.8% (95% Confidence Interval (CI): 12.8-38.6%) and 57.1% (95% CI: 35.7-71.4%), respectively. The highest seroprevalence of antibody to NDV at bird and flock levels was recorded in North Ash Sharqiyah (38.6%) and Al Buraimi (71.4%), respectively. Also, the lowest seroprevalence at bird and flock levels was recorded in Musandam (12.8%) and South Al Batinah (35.7%), respectively. A significant difference in NDV seroprevalence at flock and bird levels was only recorded in Ad Dakhliyah. Factors associated with higher seroprevalence to NDV included absence of a veterinarian in the farm (OR = 5.3; 95% CI: 2.1, 11.7), usage of dead ND vaccine (OR = 2.3; 95% CI: 1.2-4.2), employment of non-permanent staff (OR = 3.9; 95% CI: 1.5, 10.6) and free entry of visitors (OR = 6.2; 95% CI: 2.0, 20.3). In conclusion, the results of this study revealed a high exposure of backyard chickens to NDV and the identified risk factors could be vital in the prevention and control of the disease in Oman.

Whole-genome sequencing of genotype VI Newcastle disease viruses from formalin-fixed paraffin-embedded tissues from wild pigeons reveals continuous evolution and previously unrecognized genetic diversity in the U.S

Background

Newcastle disease viruses (NDV) are highly contagious and cause disease in both wild birds and poultry. A pigeon-adapted variant of genotype VI NDV, often termed pigeon paramyxovirus 1, is commonly isolated from columbids in the United States and worldwide. Complete genomic characterization of these genotype VI viruses circulating in wild columbids in the United States is limited, and due to the genetic variability of the virus, failure of rapid diagnostic detection has been reported. Therefore, in this study, formalin-fixed paraffin-embedded (FFPE) samples were subjected to next-generation sequencing (NGS) to identify and characterize these circulating viruses, providing valuable genetic information. NGS enables multiple samples to be deep-sequenced in parallel. When used on FFPE samples, this methodology allows for retrospective studies of infectious organisms.

Methods

FFPE wild pigeon tissue samples (kidney, liver and spleen) from 10 mortality events in the U.S. between 2010 and 2016 were analyzed using NGS to detect and sequence NDV genomes from randomly amplified total RNA. Results were compared to the previously published immunohistochemistry (IHC) results conducted on the same samples. Additionally, phylogenetic analyses were conducted on the complete and partial fusion gene and complete genome coding sequences.

Results

Twenty-three out of 29 IHC-positive FFPE pigeon samples were identified as positive for NDV by NGS. Positive samples produced an average genome coverage of 99.6% and an average median depth of 199. A previously described sub-genotype (VIa) and a novel sub-genotype (VIn) of NDV were identified as the causative agent of 10 pigeon mortality events in the U.S. from 2010 to 2016. The distribution of these viruses from the North American lineages match the distribution of the Eurasian collared-doves and rock pigeons in the U.S.

Conclusions

This work reports the first successful evolutionary study using deep sequencing of complete NDV genomes from FFPE samples of wild bird origin. There are at least two distinct U.S. lineages of genotype VI NDV maintained in wild pigeons that are continuously evolving independently from each other and have no evident epidemiological connections to viruses circulating abroad. These findings support the hypothesis that columbids are serving as reservoirs of virulent NDV in the U.S.

Electronic supplementary material

The online version of this article (10.1186/s12985-017-0914-2) contains supplementary material, which is available to authorized users.

A review of virulent Newcastle disease viruses in the United States and the role of wild birds in viral persistence and spread

Newcastle disease is caused by virulent strains of Newcastle disease virus (NDV), which causes substantial morbidity and mortality events worldwide in poultry. The virus strains can be differentiated as lentogenic, mesogenic, or velogenic based on a mean death time in chicken embryos. Currently, velogenic strains of NDV are not endemic in United States domestic poultry; however, these strains are present in other countries and are occasionally detected in wild birds in the U.S. A viral introduction into domestic poultry could have severe economic consequences due to the loss of production from sick and dying birds, the cost of control measures such as depopulation and disinfection measures, and the trade restrictions that would likely be imposed as a result of an outbreak. Due to the disease-free status of the U.S. and the high cost of a potential viral incursion to the poultry industry, a qualitative risk analysis was performed to evaluate the vulnerabilities of the U.S. against the introduction of virulent strains of NDV. The most likely routes of virus introduction are explored and data gathered by several federal agencies is provided. Recommendations are ultimately provided for data that would be useful to further understand NDV on the landscape and to utilize all existing sampling opportunities to begin to comprehend viral movement and further characterize the risk of NDV introduction into the U.S.

The role of vaccination in risk mitigation and control of Newcastle disease in poultry

Newcastle disease is regarded as one of the most important avian diseases throughout the world and continues to be a threat and economic burden to the poultry industry. With no effective treatment, poultry producers rely primarily on stringent biosecurity and vaccination regimens to control the spread of this devastating disease. This concise review provides an historical perspective of Newcastle disease vaccination and how fundamental research has paved the way for the development of instrumental techniques which are still in use today. Although vaccination programmes have reduced the impact of clinical disease, they have historically been ineffective in controlling the spread of virulent viruses and therefore do not always offer an adequate solution to the world's food security problems. However, the continued development of novel vaccine technology and improved biosecurity measures through education may offer a solution to help reduce the global threat of Newcastle disease on the poultry industry.

Spillover of Newcastle disease viruses from poultry to wild birds in Guangdong province, southern China

Despite intensive vaccination programs in many countries, including China, Newcastle disease has been reported sporadically and is still a significant threat to the poultry industry in China. Newcastle disease virus (NDV) is infectious for at least 250 bird species, but the role of wild birds in virus epidemiology remains largely unknown. Fourteen NDV isolates were obtained from 2040 samples collected from wild birds or the environment in Guangdong province, southern China, from 2013 to 2015. The isolation rate was the highest in the period of wintering and lowest during the periods of spring migration, nesting, and postnesting. A maximum clade credibility phylogenetic analysis revealed that at least four genotypes circulate in southern China: three class II genotypes (II, VI, and IX) and one class I (1b). We also demonstrated that most isolates from wild birds were highly similar to isolates from poultry, and two isolates were linked to viruses from wild birds in northern China. These data suggested that wild birds could disseminate NDV and poultry-derived viruses may spillover to wild birds. Accordingly, vaccine development and poultry management strategies should be considered to prevent future NDV outbreaks, particularly given the strength of the poultry industry in developing countries, such as China.

Reverse spillover of avian viral vaccine strains from domesticated poultry to wild birds

Transmission of viruses from the commercial poultry to wild birds is an emerging paradigm of livestock-wildlife interface. Here, we report the identification and isolation of vaccine strains of avian paramyxovirus serotype 1 (APMV1) and avian coronaviruses (ACoV) from different wild bird species across eight Egyptian governorates between January 2014 and December 2015. Surveillance of avian respiratory viruses in free-ranging wild birds (n=297) identified three species that harboured or excreted APMV1 and ACoVs. Genetic characterization and phylogenetic analysis of recovered viruses revealed a close association with the most widely utilized vaccine strains in the country. These results highlight the potential spillover of vaccine-viruses probably due to extensive use of live-attenuated vaccines in the commercial poultry, and close interaction between domesticated and wild bird populations. Further exploring the full spectrum of vaccine-derived viral vaccine strains in wild birds might help to assess the emergence of future wild-birds origin viruses.

Potential disease transmission from wild geese and swans to livestock, poultry and humans: a review of the scientific literature from a One Health perspective

There are more herbivorous waterfowl (swans and geese) close to humans, livestock and poultry than ever before. This creates widespread conflict with agriculture and other human interests, but also debate about the role of swans and geese as potential vectors of disease of relevance for human and animal health. Using a One Health perspective, we provide the first comprehensive review of the scientific literature about the most relevant viral, bacterial, and unicellular pathogens occurring in wild geese and swans. Research thus far suggests that these birds may play a role in transmission of avian influenza virus, Salmonella, Campylobacter, and antibiotic resistance. On the other hand, at present there is no evidence that geese and swans play a role in transmission of Newcastle disease, duck plague, West Nile virus, Vibrio, Yersinia, Clostridium, Chlamydophila, and Borrelia. Finally, based on present knowledge it is not possible to say if geese and swans play a role in transmission of Escherichia coli, Pasteurella, Helicobacter, Brachyspira, Cryptosporidium, Giardia, and Microsporidia. This is largely due to changes in classification and taxonomy, rapid development of identification methods and lack of knowledge about host specificity. Previous research tends to overrate the role of geese and swans as disease vectors; we do not find any evidence that they are significant transmitters to humans or livestock of any of the pathogens considered in this review. Nevertheless, it is wise to keep poultry and livestock separated from small volume waters used by many wild waterfowl, but there is no need to discourage livestock grazing in nature reserves or pastures where geese and swans are present. Under some circumstances it is warranted to discourage swans and geese from using wastewater ponds, drinking water reservoirs, and public beaches. Intensified screening of swans and geese for AIV, West Nile virus and anatid herpesvirus is warranted.

Assessment of contemporary genetic diversity and inter-taxa/inter-region exchange of avian paramyxovirus serotype 1 in wild birds sampled in North America

BACKGROUND

Avian paramyxovirus serotype 1 (APMV-1) viruses are globally distributed, infect wild, peridomestic, and domestic birds, and sometimes lead to outbreaks of disease. Thus, the maintenance, evolution, and spread of APMV-1 viruses are relevant to avian health.

METHODS

In this study we sequenced the fusion gene from 58 APMV-1 isolates recovered from thirteen species of wild birds sampled throughout the USA during 2007-2014. We analyzed sequence information with previously reported data in order to assess contemporary genetic diversity and inter-taxa/inter-region exchange of APMV-1 in wild birds sampled in North America.

RESULTS

Our results suggest that wild birds maintain previously undescribed genetic diversity of APMV-1; however, such diversity is unlikely to be pathogenic to domestic poultry. Phylogenetic analyses revealed that APMV-1 diversity detected in wild birds of North America has been found in birds belonging to numerous taxonomic host orders and within hosts inhabiting multiple geographic regions suggesting some level of viral exchange. However, our results also provide statistical support for associations between phylogenetic tree topology and host taxonomic order/region of sample origin which supports restricted exchange among taxa and geographical regions of North America for some APMV-1 sub-genotypes.

CONCLUSIONS

We identify previously unrecognized genetic diversity of APMV-1 in wild birds in North America which is likely a function of continued viral evolution in reservoir hosts. We did not, however, find support for the emergence or maintenance of APMV-1 strains predicted to be pathogenic to poultry in wild birds of North America outside of the order Suliformes (i.e., cormorants). Furthermore, genetic evidence suggests that ecological drivers or other mechanisms may restrict viral exchange among taxa and regions of North America. Additional and more systematic sampling for APMV-1 in North America would likely provide further inference on viral dynamics for this infectious agent in wild bird populations.

Genome-wide analysis reveals class and gene specific codon usage adaptation in avian paramyxoviruses 1

In order to characterize the evolutionary adaptations of avian paramyxovirus 1 (APMV-1) genomes, we have compared codon usage and codon adaptation indexes among groups of Newcastle disease viruses that differ in biological, ecological, and genetic characteristics. We have used available GenBank complete genome sequences, and compared codon usage of class I (CI-29 sequences containing 132,675 codons) and class II (CII-259 sequences containing 1,184,925 codons) APMV-1 genomes. We also compared available complete fusion protein gene sequences (CI-175 sequences containing 96,775 codons; CII-1166 sequences containing 644,798 codons). Adaptation to Gallus gallus was compared among the different classes of viruses, among different genomic regions based on transcriptional levels, or among the fusion gene. Interestingly, distinctive codon usage determined by differences in relative synonymous codon usage and by codon adaptation indexes was observed for the two APMV-1 classes and for different transcriptional regions within classes. Furthermore, differential use of the third codon position and preferential use of codon pairs were seen for the two different classes and for selected genotypes of class II despite the fact that there were no large differences in nucleotide composition. The data suggest that codon usage has changed significantly since the two APMV-1 classes diverged, however, these changes are not significantly pronounced among viruses of the same genotype, suggesting that codon adaptation in APMV-1 occurs through a slow evolutionary process.

Complete Genome Sequence of a Vaccinal Newcastle Disease Virus Strain Isolated from an Owl (Rhinoptynx clamator)

A Newcastle disease virus (NDV) was isolated in chicken embryonated eggs after detection by real-time reverse transcription-PCR (RRT-PCR) from a captive owl swab. The complete genome sequence of APMV-1/Rhinoptynx clamator/Brazil/22516/2009 (APMV-1, avian paramyxovirus type 1) was obtained using Illumina sequencing. Phylogenetic analysis of the complete genome classified the isolate within NDV class II genotype II.