Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Enterotropism of highly pathogenic avian influenza virus H5N8 from the 2016/2017 epidemic in some wild bird species
    Caliendo, Valentina ; Leijten, Lonneke ; Begeman, Lineke ; Poen, Marjolein J. ; Fouchier, Ron A.M. ; Beerens, Nancy ; Kuiken, Thijs - \ 2020
    Veterinary Research 51 (2020). - ISSN 0928-4249
    avian influenza - H5N1 - H5N8 - highly pathogenic - immunohistochemistry - low pathogenic - pathology - tropism - virus histochemistry - wild birds

    In 2016/2017, H5N8 highly pathogenic avian influenza (HPAI) virus of the Goose/Guangdong lineage spread from Asia to Europe, causing the biggest and most widespread HPAI epidemic on record in wild and domestic birds in Europe. We hypothesized that the wide dissemination of the 2016 H5N8 virus resulted at least partly from a change in tissue tropism from the respiratory tract, as in older HPAIV viruses, to the intestinal tract, as in low pathogenic avian influenza (LPAI) viruses, allowing more efficient faecal-oral transmission. Therefore, we determined the tissue tropism and associated lesions in wild birds found dead during the 2016 H5N8 epidemic, as well as the pattern of attachment of 2016 H5N8 virus to respiratory and intestinal tissues of four key wild duck species. We found that, out of 39 H5N8-infected wild birds of 12 species, four species expressed virus antigen in both respiratory and intestinal epithelium, one species only in respiratory epithelium, and one species only in intestinal epithelium. Virus antigen expression was association with inflammation and necrosis in multiple tissues. The level of attachment to wild duck intestinal epithelia of 2016 H5N8 virus was comparable to that of LPAI H4N5 virus, and higher than that of 2005 H5N1 virus for two of the four duck species and chicken tested. Overall, these results indicate that 2016 H5N8 may have acquired a similar enterotropism to LPAI viruses, without having lost the respirotropism of older HPAI viruses of the Goose/Guangdong lineage. The increased enterotropism of 2016 H5N8 implies that this virus had an increased chance to persist long term in the wild waterbird reservoir.

    Quantification of visits of wild fauna to a commercial free-range layer farm in the Netherlands located in an avian influenza hot-spot area assessed by video-camera monitoring
    Elbers, Armin R.W. ; Gonzales, José L. - \ 2020
    Transboundary and Emerging Diseases 67 (2020)2. - ISSN 1865-1674 - p. 661 - 677.
    avian influenza - ducks - free-range poultry - gulls - water pools - wild fauna

    Free-range poultry farms have a high risk of introduction of avian influenza viruses (AIV), and it is presumed that wild (water) birds are the source of introduction. There is very scarce quantitative data on wild fauna visiting free-range poultry farms. We quantified visits of wild fauna to a free-range area of a layer farm, situated in an AIV hot-spot area, assessed by video-camera monitoring. A total of 5,016 hr (209 days) of video recordings, covering all 12 months of a year, were analysed. A total of 16 families of wild birds and five families of mammals visited the free-range area of the layer farm. Wild birds, except for the dabbling ducks, visited the free-range area almost exclusively in the period between sunrise and the moment the chickens entered the free-range area. Known carriers of AIV visited the outdoor facility regularly: species of gulls almost daily in the period January–August; dabbling ducks only in the night in the period November–May, with a distinct peak in the period December–February. Only a small fraction of visits of wild fauna had overlap with the presence of chickens at the same time in the free-range area. No direct contact between chickens and wild birds was observed. It is hypothesized that AIV transmission to poultry on free-range poultry farms will predominantly take place via indirect contact: taking up AIV by chickens via wild-bird-faeces-contaminated water or soil in the free-range area. The free-range poultry farmer has several possibilities to potentially lower the attractiveness of the free-range area for wild (bird) fauna: daily inspection of the free-range area and removal of carcasses and eggs; prevention of forming of water pools in the free-range facility. Furthermore, there are ways to scare-off wild birds, for example use of laser equipment or trained dogs.

    Data from: Virus Shedding of Avian Influenza in Poultry: A Systematic Review and Meta-Analysis
    Germeraad, Evelien ; Sanders, Pim ; Gonzales Rojas, Jose - \ 2019
    Wageningen University & Research
    avian influenza - meta-analysis - poultry - systematic review - virus shedding
    These systematic review and meta-analysis were performed to summarize qualitative and quantitative information on virus shedding levels and duration for different AIV strains in experimentally infected poultry species.
    Virus Shedding of Avian Influenza in Poultry: A Systematic Review and Meta-Analysis
    Germeraad, Evelien A. ; Sanders, Pim ; Hagenaars, Thomas J. ; Jong, Mart C.M. de; Beerens, Nancy ; Gonzales, Jose L. - \ 2019
    Viruses 11 (2019)9. - ISSN 1999-4915
    avian influenza - meta-analysis - poultry - systematic review - virus shedding

    Understanding virus shedding patterns of avian influenza virus (AIV) in poultry is important for understanding host-pathogen interactions and developing effective control strategies. Many AIV strains were studied in challenge experiments in poultry, but no study has combined data from those studies to identify general AIV shedding patterns. These systematic review and meta-analysis were performed to summarize qualitative and quantitative information on virus shedding levels and duration for different AIV strains in experimentally infected poultry species. Methods were designed based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Four electronic databases were used to collect literature. A total of 1155 abstract were screened, with 117 studies selected for the qualitative analysis and 71 studies for the meta-analysis. A large heterogeneity in experimental methods was observed and the quantitative analysis showed that experimental variables such as species, virus origin, age, inoculation route and dose, affect virus shedding (mean, peak and duration) for highly pathogenic AIV (HPAIV), low pathogenic AIV (LPAIV) or both. In conclusion, this study highlights the need to standardize experimental procedures, it provides a comprehensive summary of the shedding patterns of AIV strains by infected poultry and identifies the variables that influence the level and duration of AIV shedding.

    Spread of Highly Pathogenic Avian Influenza (HPAI) H5N5 Viruses in Europe in 2016-2017 Appears Related to the Timing of Reassortment Events
    Bergervoet, Saskia A. ; Ho, Cynthia K.Y. ; Heutink, Rene ; Bossers, Alex ; Beerens, Nancy - \ 2019
    Viruses 11 (2019)6. - ISSN 1999-4915
    avian influenza - genetic analysis - highly pathogenic avian influenza - reassortment

    During the epizootic of highly pathogenic avian influenza (HPAI) H5N8 virus in Europe in 2016-2017, HPAI viruses of subtype H5N5 were also isolated. However, the detection of H5N5 viruses was limited compared to H5N8. In this study, we show that the genetic constellation of a newly isolated H5N5 virus is different from two genotypes previously identified in the Netherlands. The introduction and spread of the three H5N5 genotypes in Europe was studied using spatiotemporal and genetic analysis. This demonstrated that the genotypes were isolated in distinguishable phases of the epizootic, and suggested multiple introductions of H5N5 viruses into Europe followed by local spread. We estimated the timing of the reassortment events, which suggested that the genotypes emerged after the start of autumn migration. This may have prevented large-scale spread of the H5N5 viruses on wild bird breeding sites before introduction into Europe. Experiments in primary chicken and duck cells revealed only minor differences in cytopathogenicity and replication kinetics between H5N5 genotypes and H5N8. These results suggest that the limited spread of HPAI H5N5 viruses is related to the timing of the reassortment events rather than changes in virus pathogenicity or replication kinetics.

    Contrasting effects of host species and phylogenetic diversity on the occurrence of HPAI H5N1 in European wild birds
    Huang, Zheng Y.X. ; Xu, Chi ; Langevelde, Frank van; Ma, Yuying ; Langendoen, Tom ; Mundkur, Taej ; Si, Yali ; Tian, Huaiyu ; Kraus, Robert H.S. ; Gilbert, Marius ; Han, Guan Zhu ; Ji, Xiang ; Prins, Herbert H.T. ; Boer, Willem F. de - \ 2019
    Journal of Animal Ecology 88 (2019)7. - ISSN 0021-8790 - p. 1044 - 1053.
    avian influenza - community composition - dilution effect - diversity–disease relationship - phylogenetic distance - waterfowl

    Studies on the highly pathogenic avian influenza (HPAI) H5N1 suggest that wild bird migration may facilitate its long-distance spread, yet the role of wild bird community composition in its transmission risk remains poorly understood. Furthermore, most studies on the diversity–disease relationship focused on host species diversity without considering hosts’ phylogenetic relationships, which may lead to rejecting a species diversity effect when the community has host species that are only distantly related. Here, we explored the influence of waterbird community composition for determining HPAI H5N1 occurrence in wild birds in a continental-scale study across Europe. In particular, we tested the diversity–disease relationship using both host species diversity and host phylogenetic diversity. Our results provide the first demonstration that host community composition—compared with previously identified environmental risk factors—can also effectively explain the spatial pattern of H5N1 occurrence in wild birds. We further show that communities with more higher risk host species and more closely related species have a higher risk of H5N1 outbreaks. Thus, both host species diversity and community phylogenetic structure, in addition to environmental factors, jointly influence H5N1 occurrence. Our work not only extends the current theory on the diversity–disease relationship, but also has important implications for future monitoring of H5N1 and other HPAI subtypes.

    On the role of vaccine dose and antigenic distance in the transmission dynamics of Highly Pathogenic Avian Influenza (HPAI) H5N1 virus and its selected mutants in vaccinated animals
    Sitaras, Ioannis - \ 2017
    Wageningen University. Promotor(en): M.C.M. Jong, co-promotor(en): B. Peeters. - Wageningen : Wageningen University - ISBN 9789463438063 - 209
    avian influenza viruses - avian influenza - disease transmission - vaccines - vaccination - dosage - antigenic variation - mutants - mutations - immunity - vaccine development - virology - epidemiology - aviaire influenzavirussen - aviaire influenza - ziekteoverdracht - vaccins - vaccinatie - dosering - antigene variatie - mutanten - mutaties - immuniteit - vaccinontwikkeling - virologie - epidemiologie

    Influenza virus infections can cause high morbidity and mortality rates among animals and humans, and result in staggering direct and indirect financial losses amounting to billions of US dollars. Ever since it emerged in 1996 in Guangdong province, People’s Republic of China, one particular highly pathogenic avian influenza (HPAI) H5N1 virus has spread globally, and is responsible for massive losses of poultry, as well as human infections. For these reasons, HPAI H5N1 is considered as one of the viruses possible to cause a future influenza pandemic.

    One of the main reasons why influenza is a recurring problem is its ability to constantly evolve through the selection of mutants that are able to avoid immunity (be it natural or acquired). Due to the accumulation of mutations during genome replication, diverse/variant influenza genome sequences co-exist in a virus pool (quasispecies). These sequences can contain mutations that are able to confer selective advantages to the influenza virus given the opportunity. As a consequence, whenever a situation arises that places the virus under any type of pressure that the dominant virus sequence cannot cope with (i.e. immune pressure, selective receptor binding, etc.), the virus with the genome sequence that allows it to better adapt to that particular pressure becomes selected and takes over.

    Because of the influenza virus’s high rate of mutations, a global surveillance network is in place to monitor changes in circulating strains among humans that would warrant an update of the vaccines used. For human influenza strains, vaccines are updated frequently (every one or two years) and a similar situation holds true for racehorse vaccination. For avian influenza vaccination, however, the situation is different. In most countries, vaccination against avian influenza is not used, and in the countries where vaccines are used (either as routine or emergency measures), they are not updated as frequently as human vaccines are. In addition, in many instances vaccination against avian influenza viruses has met with some spectacular failures, since it failed to produce a level of immunity that would protect against circulating field strains. These vaccination failures have often been attributed to the fact that without constant vaccine updating (as is done for human influenza), the vaccines used are not able to keep up with continuously evolving antigenic variants selected in the field, and thus to protect poultry against them. In addition, since it is known that immune pressure resulting from vaccination can be a driving force in the evolution of influenza viruses and the selection of immune-escape mutants, there is a school of thought that posits that vaccination against avian influenza is not only a very expensive affair (especially if vaccines need to be frequently updated), but can also lead to selection of mutants that are able to avoid vaccination-induced immunity.

    The research reported in this thesis started with addressing the gaps in the knowledge regarding the role of vaccination-induced immunity in the selection of immune-escape mutants of HPAI H5N1, and if there is a way for vaccines to still be able to protect against antigenically-distant variants of the vaccine seed strain, without the need for frequent vaccine updates.

    Our first step in studying influenza virus evolution and selection of immune-escape mutants was to investigate how antigenic pressure may drive the selection of such mutants, and what the effect of the selected mutations on the pathogenicity and transmissibility of the mutants may be. Although there exist a variety of methods to select for influenza virus mutations (i.e. monoclonal antibodies, site-directed mutagenesis, reverse genetics, etc.), none of them is representative of selection as it happens in a vaccinated animal. In Chapter 2, we discuss in detail a laboratory-based system we have developed, in which immune-escape mutants are selected using homologous polyclonal chicken sera, similar to how they are selected in the field due to vaccination- induced immune pressure. We find that selection takes place early on, and additional mutations are selected when immune pressure is increased. Antigenic distances between the selected mutants and their parent strains are also increased throughout the selection process, but not in a linear fashion. Our selection system proved to be robust and replicable, and to be representative of selection in the field, since the mutations we selected for are also found in naturally-selected field isolates, and the antigenic distances between our selected mutants and their parent strains are similar to antigenic distances between vaccine strains and field isolates.

    We continued our research by addressing the roles played by vaccine dose (and resulting immunity) and antigenic distance between vaccine and challenge strains, in the transmission of HPAI H5N1 viruses, by employing transmission experiments using vaccinated chickens (Chapter 3). To our surprise, we found that the effect of antigenic distances between vaccine and challenge strains on transmission is very small compared to the effect of vaccine dose. We then quantified, for the first time, the minimum level of immunity and minimum percentage of the vaccinated population exhibiting said immunity, in order for vaccines to be able to protect against transmission even of strains that are antigenically distant to the vaccine seed strain. Transmission of such strains in well-vaccinated populations would allow for a scenario where vaccination- induced immunity may drive the selection of immune-escape mutants. Our results show that in order for vaccines to prevent transmission of antigenically distant strains (such as the ones resulting from selection due to immune pressure), the threshold level of immunity against these strains should be ≥23 haemagglutination inhibition units (HIU), in at least 86.5% of the vaccinated population. This level of immunity can be estimated by knowing the antigenic distance between the vaccine and challenge (field) strain, and the HI titre against the vaccine strain, which would then allow the approximate level of immunity against the field strain to be deduced. For example, assuming the HI titre against a vaccine strain is 210 HIU, and the distance with the challenge (field) strain is 24 HIU, according to our results the vaccine should be able to protect against the challenge strain, because the difference in HI titres should be around 26 HIU (i.e. above 23 HIU). These results, taken together with our previous work on selection of mutants, where we showed that the antigenic distances between our mutants and their parent strains are representative of distances found in the field, point to the fact that it is unlikely that vaccination-induced immunity can lead to selection of mutants able to escape it, given that a threshold level of immunity in a minimum percentage of the vaccinated population is achieved. As a consequence, we believe that constant vaccine updating may not be necessary for avian influenza viruses, as long as a threshold level of immunity is maintained. This makes vaccination a more attractive control measure, both from a health perspective and a financial one, than just applying biosecurity measures.

    To examine the effect the mutations in the haemagglutinin protein of our selected mutants may have in their transmission among chickens vaccinated with the parent strain, we used reverse genetics techniques to insert the HA gene of our most antigenically distant mutant into the parent strain backbone (Chapter 4). We vaccinated animals with a sub-optimal dose of vaccine, and we concluded that the mutations we selected for did not allow the mutant to avoid even low levels of immunity, such as the ones resulting from a sub-optimal vaccine dose (which resembles a poor field vaccination scenario). At the same time, the HA mutations we selected for did not appear to have a negative effect either on the pathogenicity of the mutant, or its ability to transmit to unvaccinated animals, since both parameters were comparable to the parent strain.

    Finally, we studied the role inter-animal variation in immunity – as measured by HI titres – has in the accuracy of antigenic cartography calculations (Chapter 5). We found that using sera from more than one animal significantly increased the accuracy of antigenic distance calculations, since it takes into account individual differences in immune responses to vaccination, an inevitable phenomenon documented in both humans and animals. In addition, we increased the accuracy of antigenic maps by avoiding the use of dimension-reducing algorithms as is currently done. By not reducing the dimensionality of virus positioning in space, our maps retain the original geometry between strains or sera, leading to more accurate positioning (Chapters 2 and 5). We hope that improving the accuracy of antigenic cartography can lead to a more precise surveillance of influenza evolution and better informed decisions regarding the need to update vaccines.

    Taken collectively, our results can improve field vaccination outcomes, since they provide guidelines on how to increase vaccination efficiency in stopping transmission of even antigenically-distant strains. In addition, our method for selecting for immune- escape mutants can be a valuable addition to research on influenza virus evolution. Moreover, policy making decisions regarding vaccination against any type of influenza can also benefit from our improvement on antigenic cartography accuracy, saving unnecessary costs in vaccine updating, and reducing morbidity and mortality of both animals and humans.

    Handelingsperspectief voor pluimveehouders in de preventie van laag- en hoogpathogene vogelgriep (AI)
    Bokma, Martien ; Bergevoet, Ron ; Elbers, Armin ; Goot, Jeanet van der; Neijenhuis, Francesca ; Niekerk, Thea van; Leenstra, Ferry - \ 2016
    Wageningen : Wageningen Livestock Research (Wageningen Livestock Research rapport 998) - 42
    aviaire influenza - hennen - pluimveehouderij - boeren - dierziektepreventie - risicofactoren - avian influenza - hens - poultry farming - farmers - animal disease prevention - risk factors
    Committed by the Dutch poultry sector research is carried out concerning acting perspective for prevention of AI-introduction on poultry farms, based on existing knowledge. The findings are shown in two parts: part I with practical advices for poultry farmers, and part II with its underpinning with a summary of existing knowledge of risk factors, preventive measures, early detection and possibilities for promoting desired (preventive) behaviour.
    Learning to live with bird flu
    Bouwstra, R.J. ; Poel, W.H.M. van der - \ 2015
    animal welfare - animal production - poultry - animal health - avian influenza - fowls
    H5N8 in Nederland in 2014 : Een nadere blik op de uitbraken
    Velkers, F.C. ; Elbers, A.R.W. ; Bouwstra, R.J. ; Stegeman, A. - \ 2015
    dierenwelzijn - dierlijke productie - pluimvee - dierziekten - diergezondheid - aviaire influenza - pluimveehouderij - animal welfare - animal production - poultry - animal diseases - animal health - avian influenza - poultry farming
    In opdracht van het Ministerie van Economische Zaken (EZ) is een analyse uitgevoerd van de H5N8 uitbraken om nader inzicht in binnenkomst, verspreiding en symptomen van het virus op pluimveebedrijven te krijgen. De bevindingen zijn tussentijds gerapporteerd via het overleg van de deskundigengroep dierziekten. De volledige
    rapportage is eind 2014 aangeboden aan het Ministerie van EZ. Dit document is een samenvatting hiervan.
    Eight challenges in modelling infectious livestock diseases
    Brooks-Pollock, E. ; Jong, M. de; Keeling, M.J. ; Klinkenberg, D. ; Wood, J.L.N. - \ 2015
    Epidemics 10 (2015). - ISSN 1755-4365 - p. 1 - 5.
    mouth-disease - great-britain - bovine tuberculosis - virus transmission - avian influenza - dynamic-model - uk foot - cattle - epidemic - impact
    The transmission of infectious diseases of livestock does not differ in principle from disease transmission in any other animals, apart from that the aim of control is ultimately economic, with the influence of social, political and welfare constraints often poorly defined. Modelling of livestock diseases suffers simultaneously from a wealth and a lack of data. On the one hand, the ability to conduct transmission experiments, detailed within-host studies and track individual animals between geocoded locations make livestock diseases a particularly rich potential source of realistic data for illuminating biological mechanisms of transmission and conducting explicit analyses of contact networks. On the other hand, scarcity of funding, as compared to human diseases, often results in incomplete and partial data for many livestock diseases and regions of the world. In this overview of challenges in livestock disease modelling, we highlight eight areas unique to livestock that, if addressed, would mark major progress in the area.
    Dierenlab beschermt mensen
    Sikkema, A. ; Bianchi, A.T.J. - \ 2015
    WageningenWorld (2015)1. - ISSN 2210-7908 - p. 24 - 27.
    dierziekten - infectieziekten - zoönosen - virusziekten - onderzoek - diergezondheid - vaccins - aviaire influenza - q-koorts - animal diseases - infectious diseases - zoonoses - viral diseases - research - animal health - vaccines - avian influenza - q fever
    Nederland krijgt steeds meer te maken met besmettelijke dierziektes die ook mensen ziek kunnen maken, zoals vogelgriep. Om daar goed onderzoek naar te doen is een lab gebouwd waarin levende, besmette landbouwhuisdieren gehouden worden. Geen virus kan eruit ontsnappen. ‘Zelfs het DNA wordt vernietigd.’
    Vogelgriepvirus kwam aanvliegen uit Azië
    Sikkema, A. ; Bouwstra, R.J. - \ 2014
    Resource: weekblad voor Wageningen UR 9 (2014)8. - ISSN 1874-3625 - p. 8 - 8.
    aviaire influenza - aviaire influenzavirussen - besmetting - pluimveehouderij - pluimvee - diergezondheid - dierenwelzijn - ziekteoverdracht - dierlijke productie - avian influenza - avian influenza viruses - contamination - poultry farming - poultry - animal health - animal welfare - disease transmission - animal production
    CVI acht besmetting via trekvogels 'waarschijnlijk.' Het virus komt oorspronkelijk uit China.
    Risk of poultry compartments for transmission of High Pathogenic Avian Influenza
    Boender, G.J. ; Hagenaars, T.H.J. ; Backer, J.A. ; Nodelijk, G. ; Asseldonk, M.A.P.M. van; Bergevoet, R.H.M. ; Roermund, H.J.W. van - \ 2014
    Lelystad : CVI en LEI (Report number CVI: 14/I00028 ) - 28
    aviaire influenza - pluimveeziekten - pluimveehouderij - compartimenten - ziekteoverdracht - pathogeniteit - eu regelingen - wetgeving - diergezondheid - dierenwelzijn - pluimvee - avian influenza - poultry diseases - poultry farming - compartments - disease transmission - pathogenicity - eu regulations - legislation - animal health - animal welfare - poultry
    The application for a poultry compartment by VPI and the prospect of further ones motivates the Dutch Ministry of Economic Affairs and the Netherlands Food and Consumer Product Safety Authority to raise the following three questions: 1) What are the additional transmission risks that the (specific) VPI compartment poses during an HPAI epidemic, compared to a situation without compartment?; 2) What are the additional transmission risks that a compartment in general poses during an HPAI epidemic, depending on its characteristics?; 3) What are relevant evaluation criteria for granting the compartment status? In this study we addressed these questions by quantitatively assessing the veterinary risks based on mathematical model calculations, and by qualitatively discussing the (socio) economic aspects.
    Laag pathogene aviaire influenza virus infecties op pluimveebedrijven in Nederland
    Goot, J.A. van der; Verhagen, J. ; Gonzales, J. ; Backer, J.A. ; Bongers, J.H. ; Boender, G.J. ; Fouchier, R.A.M. ; Koch, G. - \ 2013
    Tijdschrift voor Diergeneeskunde 138 (2013)6. - ISSN 0040-7453 - p. 24 - 29.
    pluimveehouderij - pluimveeziekten - aviaire influenza - hennen - kippen - ziekte-incidentie - huisvesting, dieren - agrarische productiesystemen - uitloop - risicofactoren - poultry farming - poultry diseases - avian influenza - hens - fowls - disease incidence - animal housing - agricultural production systems - outdoor run - risk factors
    Dit artikel is een samenvatting van het rapport "Laag pathogene aviaire influenza virus iInfecties op pluimveebedrijven in Nederland" (CVI 2012). Dit rapport is geschreven naar aanleiding van vragen van het toenmalige Ministerie van Economische zaken, Landbouw en Innovatie. De vragen die werden gesteld zijn: - hebben pluimveebedrijven met vrije uitloop een grotere kans op introductie van LPAI virus infecties?; - is de kans op introductie gerelateerd aan wilde vogels?; - is er een periode in het jaar waarin het risico op infectie groter is? - kunnen er factoren geidentificeerd worden die de kans op introductie verminderen?
    Guiding outbreak management by the use of influenza A(H7Nx) virus sequence analysis
    Jonges, M. ; Meijer, A. ; Fouchier, R.A.M. ; Koch, G. ; Li, J. ; Pan, J.C. ; Shu, Y.L. ; Koopmans, M.P.G. ; Chen, H. - \ 2013
    Eurosurveillance 18 (2013)16. - ISSN 1025-496X - 8 p.
    avian influenza - a virus - transmission - replication - poultry - ferrets - humans - mice
    The recently identified human infections with avian influenza A(H7N9) viruses in China raise important questions regarding possible source and risk to humans. Sequence comparison with an influenza A(H7N7) outbreak in the Netherlands in 2003 and an A(H7N1) epidemic in Italy in 1999–2000 suggests that widespread circulation of A(H7N9) viruses must have occurred in China. The emergence of human adaptation marker PB2 E627K in human A(H7N9) cases parallels that of the fatal A(H7N7) human case in the Netherlands.
    Agroterrorism targeting livestock: a review with a focus on early detection systems
    Elbers, A.R.W. ; Knutsson, R. - \ 2013
    Biosecurity and Bioterrorism: biodefense strategy, practice and science 11 (2013)s1. - ISSN 1538-7135 - p. S25 - S35.
    classical swine-fever - mouth-disease epidemic - avian influenza - descriptive epidemiology - biological terrorism - animal-disease - agricultural diseases - clinical signs - united-states - foot
    Agroterrorism targeting livestock can be described as the intentional introduction of an animal disease agent against livestock with the purpose of causing economic damage, disrupting socioeconomic stability of a country, and creating panic and distress. This type of terrorism can be alluring to terrorists because animal disease agents are easily available. This review addresses the vulnerabilities of the livestock industry to agroterrorism. However, we also show that early detection systems have recently been developed for agroterrorism and deliberate spread of animal pathogens in livestock, including an agroterrorism intelligence cycle, syndromic surveillance programs, and computer-based clinical decision support systems that can be used for early detection of notifiable animal diseases. The development of DIVA-vaccines in the past 10 to 15 years has created, in principle, an excellent response instrument to counter intentional animal disease outbreaks. These developments have made our animal agriculture less vulnerable to agroterrorism. But we cannot relax; there are still many challenges, in particular with respect to integration of first line of defense, law enforcement, and early detection systems for animal diseases.
    Vogelgriep ontrafeld : resultaten FES-AI onderzoeksprogramma
    Luijkx, D.L.M. ; Scholtens, B. ; Nijland, H.R. - \ 2012
    Lelystad : CVI - ISBN 9789461734907 - 62
    aviaire influenza - aviaire influenzavirussen - vogels - pluimveehouderij - epidemieën - dierziektepreventie - ziektebestrijding - vaccinatie - diagnostiek - virologie - nederland - avian influenza - avian influenza viruses - birds - poultry farming - epidemics - animal disease prevention - disease control - vaccination - diagnostics - virology - netherlands
    Vogelgriep en mensengriep zijn nauwe verwanten: beide worden meestal veroorzaakt door zogeheten Influenza-A-virussen. Zo'n griepvirus is een mini-kikkertje van hooguit honderd nanometer (0,0001 milimeter) doorsnede met eiwituitstulpingen aan de buitenkant. Daarmee klampt het virusbolletje zich vast aan de cellen van zijn gastheer. Die hechting heeft het nodig om de cel te infecteren en zichzelf daarna te kunnen vermenigvuldigen. Dit boekje heeft de vogelgriepuitbraak van 2003 in Nederland als startpunt. Welke dilemma's deden zich toen voor en welke bestrijdingsmogelijkheden waren er voorhanden? Vanwege de twijfels, vragen en onzekerheden werd het FES-AI onderzoeksprogramma in het leven geroepen. Het FES-AI programma is opgedeeld in 7 verschillende kennisvelden. Voor de samenstelling van dit boekje is gesproken met de onderzoekleiders, die het onderzoek vorm hebben gegeven.
    Protective Efficacy of Newcastle Disease Virus Expressing Soluble Trimeric Hemagglutinin against Highly Pathogenic H5N1 Influenza in Chickens and Mice
    Cornelissen, A.H.M. ; Leeuw, O.S. de; Tacken, M.G.J. ; Klos, H.C. ; Vries, R.P. de; Boer-Luijtze, E.A. de; Zoelen-Bos, D.J. van; Rigter, A. ; Rottier, P.J.M. ; Moormann, R.J.M. ; Haan, C.A.M. de - \ 2012
    PLoS ONE 7 (2012)8. - ISSN 1932-6203
    avian influenza - fusion protein - neutralizing antibodies - respiratory-tract - lethal challenge - vaccine vectors - fowlpox virus - recombinant - immunization - virulence
    Background: Highly pathogenic avian influenza virus (HPAIV) causes a highly contagious often fatal disease in poultry, resulting in significant economic losses in the poultry industry. HPAIV H5N1 also poses a major public health threat as it can be transmitted directly from infected poultry to humans. One effective way to combat avian influenza with pandemic potential is through the vaccination of poultry. Several live vaccines based on attenuated Newcastle disease virus (NDV) that express influenza hemagglutinin (HA) have been developed to protect chickens or mammalian species against HPAIV. However, the zoonotic potential of NDV raises safety concerns regarding the use of live NDV recombinants, as the incorporation of a heterologous attachment protein may result in the generation of NDV with altered tropism and/or pathogenicity. Methodology/Principal Findings: In the present study we generated recombinant NDVs expressing either full length, membrane-anchored HA of the H5 subtype (NDV-H5) or a soluble trimeric form thereof (NDV-sH5 3). A single intramuscular immunization with NDV-sH5 3 or NDV-H5 fully protected chickens against disease after a lethal challenge with H5N1 and reduced levels of virus shedding in tracheal and cloacal swabs. NDV-sH5 3 was less protective than NDV-H5 (50% vs 80% protection) when administered via the respiratory tract. The NDV-sH5 3 was ineffective in mice, regardless of whether administered oculonasally or intramuscularly. In this species, NDV-H5 induced protective immunity against HPAIV H5N1, but only after oculonasal administration, despite the poor H5-specific serum antibody response it elicited. Conclusions/Significance: Although NDV expressing membrane anchored H5 in general provided better protection than its counterpart expressing soluble H5, chickens could be fully protected against a lethal challenge with H5N1 by using the latter NDV vector. This study thus provides proof of concept for the use of recombinant vector vaccines expressing a soluble form of a heterologous viral membrane protein. Such vectors may be advantageous as they preclude the incorporation of heterologous membrane proteins into the viral vector particles.
    Cell culture based production of avian influenza vaccines
    Wielink, R. van - \ 2012
    Wageningen University. Promotor(en): Rene Wijffels; Rob Moormann, co-promotor(en): Michael Harmsen; Dirk Martens. - S.l. : s.n. - ISBN 9789461733535 - 141
    aviaire influenza - aviaire influenza a-virussen - celcultuur vaccins - vaccins - celkweek - virologie - bioproceskunde - veeartsenijkunde - avian influenza - avian influenza a viruses - cell culture vaccines - vaccines - cell culture - virology - bioprocess engineering - veterinary medicine

    Vaccination of poultry can be used as a tool to control outbreaks of avian influenza, including that of highly pathogenic H5 and H7 strains. Influenza vaccines are traditionally produced in embryonated chicken eggs. Continuous cell lines have been suggested as an alternative substrate to produce influenza vaccines, as they are more robust and lack the long lead times associated with the production of large quantities of embryonated eggs. In the study that is described in this thesis, the production of influenza virus in cell culture was explored. Therefore, several cell lines were assessed for their ability to propagate influenza virus. Furthermore, adaptations to both cell line and seed virus were suggested that increased virus yield, thereby allowing the production of attenuated influenza virus strains.

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