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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    Circulation of four Anaplasma phagocytophilum ecotypes in Europe
    Jahfari, S. ; Coipan, E.C. ; Fonville, M. ; Leeuwen, A.D. van; Hengeveld, P. ; Heylen, D. ; Heyman, P. ; Maanen, C. van; Butler, C.M. ; Foldvari, G. ; Szekeres, S. ; Duijvendijk, L.A.G. van; Tack, W. ; Rijks, J.M. ; Giessen, J. van der; Takken, W. ; Wieren, S.E. van; Takumi, K. ; Sprong, H. - \ 2014
    Parasites & Vectors 7 (2014)1. - ISSN 1756-3305
    candidatus neoehrlichia mikurensis - human granulocytic anaplasmosis - ixodes-ricinus ticks - borrelia-burgdorferi - borne diseases - phylogenetic analyses - sequence-analysis - ehrlichiosis - strains - gene
    Background: Anaplasma phagocytophilum is the etiological agent of granulocytic anaplasmosis in humans and animals. Wild animals and ticks play key roles in the enzootic cycles of the pathogen. Potential ecotypes of A. phagocytophilum have been characterized genetically, but their host range, zoonotic potential and transmission dynamics has only incompletely been resolved. Methods. The presence of A. phagocytophilum DNA was determined in more than 6000 ixodid ticks collected from the vegetation and wildlife, in 289 tissue samples from wild and domestic animals, and 69 keds collected from deer, originating from various geographic locations in The Netherlands and Belgium. From the qPCR-positive lysates, a fragment of the groEL-gene was amplified and sequenced. Additional groEL sequences from ticks and animals from Europe were obtained from GenBank, and sequences from human cases were obtained through literature searches. Statistical analyses were performed to identify A. phagocytophilum ecotypes, to assess their host range and their zoonotic potential. The population dynamics of A. phagocytophilum ecotypes was investigated using population genetic analyses. Results: DNA of A. phagocytophilum was present in all stages of questing and feeding Ixodes ricinus, feeding I. hexagonus, I. frontalis, I. trianguliceps, and deer keds, but was absent in questing I. arboricola and Dermacentor reticulatus. DNA of A. phagocytophilum was present in feeding ticks and tissues from many vertebrates, including roe deer, mouflon, red foxes, wild boar, sheep and hedgehogs but was rarely found in rodents and birds and was absent in badgers and lizards. Four geographically dispersed A. phagocytophilum ecotypes were identified, that had significantly different host ranges. All sequences from human cases belonged to only one of these ecotypes. Based on population genetic parameters, the potentially zoonotic ecotype showed significant expansion. Conclusion: Four ecotypes of A. phagocytophilum with differential enzootic cycles were identified. So far, all human cases clustered in only one of these ecotypes. The zoonotic ecotype has the broadest range of wildlife hosts. The expansion of the zoonotic A. phagocytophilum ecotype indicates a recent increase of the acarological risk of exposure of humans and animals.
    Development and validation of an indirect Enzyme-linked Immunosorbent Assay for the detection of antibodies against Schmallenberg virus in blood samples from ruminants
    Heijden, H.M.J.F. van der; Bouwstra, R.J. ; Mars, M.H. ; Poel, W.H.M. van der; Wellenberg, G.J. ; Maanen, C. van - \ 2013
    Research in Veterinary Science 95 (2013)2. - ISSN 0034-5288 - p. 731 - 735.
    akabane virus - simbu serogroup - cattle - bovine - europe
    To detect Schmallenberg virus (SBV) infections in ruminants and to perform SBV epidemiological studies a cost-effective serological test is required. For these purposes an indirect whole virus Enzyme-linked Immunosorbent Assay (ELISA) for detection of SBV specific antibodies in ruminant blood samples was developed. Schmallenberg virus antigen was produced by propagation on Vero cells, partly purified and coated onto ELISA plates. The indirect ELISA procedure included the subsequent incubation of diluted samples, protein-G-HRP conjugate and TMB substrate solution. Net Optical Densities (OD) values were calculated and expressed as a sample to positive percentage (S/P%) by comparison of the average net OD with the OD of the positive control. Validation of this assay was performed using 633 samples from SBV-free sheep, goats and cattle, and 141 samples from SBV suspect ruminants. The diagnostic specificity was 98.8%. Test results of 86 ruminant serum samples using both the SBV-ELISA and an SBV virus neutralization test (VNT), designated as the gold standard serological test for SBV, showed good correlation: at an S/P cut-off of 15% only one VNT positive sample tested negative in the SBV ELISA. The diagnostic sensitivity of the ELISA, relative to the VNT, was 98.8% (95% CI: 93.3-100.0%). The ELISA showed a high repeatability (cv=6.5%) and reproducibility (100% agreement). It was concluded that this ELISA is a suitable test method for the detection of SBV antibodies in sera from cows, sheep and, possibly, goats.
    Schmallenberg virus outbreak in the Netherlands: Routine diagnostics and test results
    Bouwstra, R.J. ; Kooi, E.A. ; Kluijver, E.P. de; Verstraten, E.R.A.M. ; Bongers, J.H. ; Maanen, C. van; Wellenberg, G.J. ; Spek, A.N. van der; Poel, W.H.M. van der - \ 2013
    Veterinary Microbiology 165 (2013)1-2. - ISSN 0378-1135 - p. 102 - 108.
    akabane virus - antibodies - cattle - orthobunyavirus - shamonda - nigeria - bovine
    In 2006 and 2007 pig farming in the region of Lombardy, in the north of Italy, was struck by an epidemic of Swine Vesicular Disease virus (SVDV). In fact this epidemic could be viewed as consisting of two sub-epidemics, as the reported outbreaks occurred in two separate time periods. These periods differed in terms of the provinces or municipalities that were affected and also in terms of the timing of implementation of movement restrictions. Here we use a simple mathematical model to analyse the epidemic data, quantifying between-farm transmission probability as a function of between-farm distance. The results show that the distance dependence of between-farm transmission differs between the two periods. In the first period transmission over relatively long distances occurred with higher probability than in the second period, reflecting the effect of movement restrictions in the second period. In the second period however, more intensive transmission occurred over relatively short distances. Our model analysis explains this in terms of the relatively high density of pig farms in the area most affected in this period, which exceeds a critical farm density for between-farm transmission. This latter result supports the rationale for the additional control measure taken in 2007 of pre-emptively culling farms in that area.
    Schmallenberg virus antibodies in bovine and ovine foetuses
    Maanen, C. van; heijden, H. van der; Wellenberg, G.J. ; Witteveen, G. ; Luttikholt, S. ; Vellema, P. ; Peperkamp, K. ; Mars, J. ; Bouwstra, R.J. ; Kooi, B. - \ 2012
    Veterinary Record 171 (2012)12. - ISSN 0042-4900
    akabane virus - arthrogryposis - cattle - infection
    We conclude that testing for antibodies against SBV in foetal or neonatal precolostral serum samples, either by ELISA or VNT, is a valuable tool to diagnose SBV infections in affected lambs and calves as it is for related viruses like Akabane virus.
    Evaluation of an indirect ELISA for detection of antibodies in bulk mlik against bluetongue virus infections in the Netherlands
    Mars, M.H. ; Maanen, C. van; Vellema, P. ; Kramps, J.A. ; Rijn, P.A. van - \ 2010
    Veterinary Microbiology 146 (2010)3-4. - ISSN 0378-1135 - p. 209 - 214.
    linked immunosorbent assays - individual milk - dairy herds - cattle - samples
    After the introduction of bluetongue virus serotype 8 (BTV-8) in western Europe in 2006, an indirect ELISA for detection of serogroup-specific antibodies against BTV in serum samples was validated for individual milk samples by the Central Veterinary Institute and the Animal Health Service in the Netherlands (Kramps et al., 2008). In order to develop a cost-effective monitoring tool, we now have evaluated this ELISA also for use in bulk milk. Therefore, bulk milk samples and individual milk samples were collected from 92 herds in the affected southern region in the Netherlands in 2007, before the start of the vaccination campaign. In addition, bulk milk samples collected from 88 herds before the bluetongue introduction in 2006 (“historically negative” samples) have been tested. With these results ROC analyses were performed and herd specificity and herd sensitivity of the bulk milk ELISA were estimated. All “historically negative” bulk milk samples were negative in the ELISA, with a mean S/P ratio of 10 ± 0.8%. The herd sensitivity and herd specificity of the ELISA in bulk milk samples depend on the cut-off that is chosen. In order to detect a within-herd-prevalence of 1%, the optimal cut-off S/P ratio 13% was found. A few herds with one or two milk-positive animals would then be missed. The specificity will be 100%. A within-herd-prevalence of 10% can be detected with 100% sensitivity at a cut-off S/P ratio of 96%. In conclusion, the indirect ELISA in bulk milk samples is a very specific and sensitive test which can be implemented in monitoring and surveillance systems in unvaccinated populations.
    'Emerging vector-borne diseases' bij het paard
    Sloet van Oldruitenborgh-Oosterbaan, M.M. ; Goehring, L.S. ; Koopmans, M.P.G. ; Rijn, P.A. van; Maanen, C. van - \ 2009
    Tijdschrift voor Diergeneeskunde 134 (2009)10. - ISSN 0040-7453 - p. 439 - 447.
    Validation of a commercial ELISA kit for detection of antibodies to bluetongue virus in individual milk samples of dutch dairy cows
    Kramps, J.A. ; Maanen, C. van; Mars, J. ; Popma, J.K. ; Rijn, P.A. van - \ 2007
    The effect of maternal antibodies on the detection of bovine virus diarrhoea virus in peripheral blood samples
    Zimmer, G.M. ; Maanen, C. van; Goey, I. de; Brinkhof, J. ; Wentink, G.H. - \ 2004
    Veterinary Microbiology 100 (2004)3-4. - ISSN 0378-1135 - p. 145 - 149.
    infection - cattle - vaccination - bvdv
    Persistently infected animals (PI animals), that is those animals born after an intrauterine infection of the dam during the first 120 days of gestation, are the main source of bovine virus diarrhoea virus (BVD virus) in a cattle population. The success of any BVD virus eradication programme depends on the ability to detect all PI animals at a young age. The purpose of this study was to evaluate the use of the antigen ELISA test and the reverse transcriptase-polymerase chain reaction (RT-PCR) test for the diagnosis of PI animals in the presence of maternal antibodies, and to compare them with the classical virus isolation test. In this experiment, 25 calves born after an experimental infection with a mixture of BVD virus field strains were used. All calves were found to be positive for BVD virus using the virus isolation test, both before the ingestion of colostrum and again at 10 weeks of age. Both the virus isolation test and the antigen ELISA test were shown to be unreliable indicators for the diagnosis of persistent infections with BVD virus, when used in the presence of high levels of maternal antibodies. However, the RT-PCR test gave positive results even in the presence of high maternal antibody titres, indicating the suitability of the RT-PCR test for use in eradication programmes.
    Diagnostic methods applied to analysis of an outbreak of equine influenza in a riding school in which vaccine failure occurred
    Maanen, C. van; Essen, G.J. van; Minke, J. ; Daly, J.M. ; Yates, P.J. - \ 2003
    Veterinary Microbiology 93 (2003)4. - ISSN 0378-1135 - p. 291 - 306.
    a viruses - horses - gene
    An outbreak of equine influenza H3N8 in a riding school is described retrospectively with emphasis on diagnosis and putative vaccine failure. In March 1995 an outbreak of equine influenza occurred among 11 horses in a riding school, where most horses had received basic primary immunizations and several booster vaccinations against influenza. Six of the 11 diseased horses had received their last booster vaccination within 5 months of the outbreak. Nevertheless, the influenza infection spread rapidly and clinical manifestations were prominent with frequent, harsh, dry coughing often accompanied by high fever. Nasal swabs were taken from 11 diseased horses. Influenza A virus of the equine H3N8 (equi-2) subtype was isolated from five nasal swab extracts. Stored nasal swab extracts were also retrospectively investigated in two different enzyme immunoassays designed to detect the type-specific conserved nucleoprotein of influenza A viruses, and in a single-tube reverse transcription-PCR (RT-PCR) using a set of primers based on highly conserved regions of the matrix gene of influenza A viruses. Five nasal swab extracts were found positive in a DAS-ELISA and seven in the Directigen® Flu A (DFA) assay, respectively. Two nasal swab extracts from which virus was isolated did not give a positive result in the DAS-ELISA, and one of these also did not give a positive result in the DFA assay. Nine nasal swab extracts were found positive by RT-PCR. Moreover, all virus isolation and/or ELISA positive nasal swab extracts were confirmed by RT-PCR. Three nasal swab extracts were negative by virus isolation, PCR and ELISA. A significant rise in HI titre against influenza A/eq/Miami/63 (H3N8) virus was detected in seven of the nine paired sera available. In acute phase serum samples from 10 horses, SRH antibody levels varied widely. However, some horses with high, or at least putatively clinically protective SRH antibody levels, showed clinical signs and infection was confirmed. Antigenic analysis of two isolates showed that A/eq/Holland/1/95 (H3N8) and A/eq/Holland/2/95 (H3N8) cluster with the UK isolate Osgodsby/92, the Swedish isolate Borlänge/91 and some other European isolates, with H/2/95 identical in reactivity to Borlänge/91 and H/1/95 more similar in reactivity to Osgodsby/92 than H/2/95. Nucleotide and deduced amino-acid sequences showed large differences of both isolates as compared with Miami/63, Fontainebleau/79 and Kentucky/81, the influenza A H3N8 subtype strains incorporated in the vaccines used in this riding school. The role of antigenic drift in vaccine breakdown is discussed in the light of evidence for vaccine breakdown in the UK in 1989, Sweden in 1991 and in the USA since 1991.
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