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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The relationship between the presence of antibodies and direct detection of Toxoplasma gondii in slaughtered calves and cattle in four European countries
Opsteegh, M. ; Spano, F. ; Aubert, D. ; Balea, A. ; Burrells, A. ; Cherchi, S. ; Cornelissen, J.B.W.J. ; Dam-Deisz, C. ; Guitian, J. ; Györke, A. ; Innes, E.A. ; Katzer, F. ; Limon, G. ; Possenti, A. ; Pozio, E. ; Schares, G. ; Villena, I. ; Wisselink, H.J. ; Giessen, J.W.B. van der - \ 2019
International Journal for Parasitology 49 (2019)7. - ISSN 0020-7519 - p. 515 - 522.
Cattle - Detection - Mouse bioassay - PCR - Serology - Toxoplasma gondii

In cattle, antibodies to Toxoplasma gondii infection are frequently detected, but evidence for the presence of T. gondii tissue cysts in cattle is limited. To study the concordance between the presence of anti-T. gondii IgG and viable tissue cysts of T. gondii in cattle, serum, liver and diaphragm samples of 167 veal calves and 235 adult cattle were collected in Italy, the Netherlands, Romania and the United Kingdom. Serum samples were tested for anti-T. gondii IgG by the modified agglutination test and p30 immunoblot. Samples from liver were analyzed by mouse bioassay and PCR after trypsin digestion. In addition, all diaphragms of cattle that had tested T. gondii-positive (either in bioassay, by PCR on trypsin-digested liver or serologically by MAT) and a selection of diaphragms from cattle that had tested negative were analyzed by magnetic capture quantitative PCR (MC-PCR). Overall, 13 animals were considered positive by a direct detection method: seven out of 151 (4.6%) by MC-PCR and six out of 385 (1.6%) by bioassay, indicating the presence of viable parasites. As cattle that tested positive in the bioassay tested negative by MC-PCR and vice-versa, these results demonstrate a lack of concordance between the presence of viable parasites in liver and the detection of T. gondii DNA in diaphragm. In addition, the probability to detect T. gondii parasites or DNA in seropositive and seronegative cattle was comparable, demonstrating that serological testing by MAT or p30 immunoblot does not provide information about the presence of T. gondii parasites or DNA in cattle and therefore is not a reliable indicator of the risk for consumers.

Emergence of carp edema virus (CEV) and its significance to European common carp and koi Cyprinus carpio
Way, K. ; Haenen, O. ; Stone, D. ; Adamek, M. ; Bergmann, S.M. ; Bigarré, L. ; Diserens, Nicolas ; El-Matbouli, M. ; Gjessing, M.C. ; Jung-Schroers, V. ; Leguay, E. ; Matras, M. ; Olesen, Niels J. ; Panzarin, Valentina ; Piačková, V. ; Toffan, A. ; Vendramin, N. ; Veselý, T. ; Waltzek, T. - \ 2017
Diseases of Aquatic Organisms 126 (2017)2. - ISSN 0177-5103 - p. 155 - 166.
Aquaculture - CEVD - Cyprinus carpio - Koi sleepy disease - PCR - Poxvirus
Carp edema virus disease (CEVD), also known as koi sleepy disease, is caused by a poxvirus associated with outbreaks of clinical disease in koi and common carp Cyprinus carpio. Originally characterised in Japan in the 1970s, international trade in koi has led to the spread of CEV, although the first recognised outbreak of the disease outside of Japan was not reported until 1996 in the USA. In Europe, the disease was first recognised in 2009 and, as detection and diagnosis have improved, more EU member states have reported CEV associated with disease outbreaks. Although the structure of the CEV genome is not yet elucidated, molecular epidemiology studies have suggested distinct geographical populations of CEV infecting both koi and common carp. Detection and identification of cases of CEVD in common carp were unreliable using the original PCR primers. New primers for conventional and quantitative PCR (qPCR) have been designed that improve detection, and their sequences are provided in this paper. The qPCR primers have successfully detected CEV DNA in archive material from investigations of unexplained carp mortalities conducted >15 yr ago. Improvement in disease management and control is possible, and the principles of biosecurity, good health management and disease surveillance, applied to koi herpesvirus disease, can be equally applied to CEVD. However, further research studies are needed to fill the knowledge gaps in the disease pathogenesis and epidemiology that, currently, prevent an accurate assessment of the likely impact of CEVD on European koi and common carp aquaculture and on wild carp stocks.
Predicting the ability of preclinical diagnosis to improve control of farm-to-farm foot-and-mouth disease transmission in cattle
Nelson, Noel ; Paton, David J. ; Gubbins, Simon ; Colenutt, Claire ; Brown, Emma ; Hodgson, Sophia ; Gonzales Rojas, Jose - \ 2017
Journal of Clinical Microbiology 55 (2017)6. - ISSN 0095-1137 - p. 1671 - 1681.
Diagnostics - Early detection - FMD - Foot-and-mouth disease virus - PCR - Sensitivity - Surveillance - Transmission

Foot-and-mouth disease (FMD) can cause large disruptive epidemics in livestock. Current eradication measures rely on the rapid clinical detection and removal of infected herds. Here, we evaluated the potential for preclinical diagnosis during reactive surveillance to reduce the risk of between-farm transmission. We used data from transmission experiments in cattle where both samples from individual animals, such as blood, probang samples, and saliva and nasal swabs, and herd-level samples, such as air samples, were taken daily during the course of infection. The sensitivity of each of these sample types for the detection of infected cattle during different phases of the early infection period was quantified. The results were incorporated into a mathematical model for FMD, in a cattle herd, to evaluate the impact of the early detection and culling of an infected herd on the infectious output. The latter was expressed as the between-herd reproduction ratio, Rh, where an effective surveillance approach would lead to a reduction in the Rh value to <1. Applying weekly surveillance, clinical inspection alone was found to be ineffective at blocking transmission. This was in contrast to the impact of weekly random sampling (i.e., using saliva swabs) of at least 10 animals per farm or daily air sampling (housed cattle), both of which were shown to reduce the Rh to <1. In conclusion, preclinical detection during outbreaks has the potential to allow earlier culling of infected herds and thereby reduce transmission and aid the control of epidemics.

Presence of Coxiella burnetii DNA in inflamed bovine cardiac valves
Agerholm, Jørgen S. ; Jensen, Tim K. ; Agger, Jens F. ; Engelsma, Marc Y. ; Roest, Hendrik-Jan - \ 2017
BMC Veterinary Research 13 (2017)1. - ISSN 1746-6148
Cattle - Coxiella burnetii - Endocarditis - PCR - Q fever

Background: Bacterial endocarditis is a recognised disease in humans and animals. In humans, infection with Coxiella burnetii can cause endocarditis, but this has not been investigated thoroughly in animals. Endocarditis in cattle is a common post-mortem finding in abattoirs and studies have identified Trueperella pyogenes as a major cause. Despite exposure of cattle to C. burnetii, the significance of this particular bacterium for development and progression of endocarditis has not been studied in detail. Cardiac valves of cattle affected with endocarditis (n = 100) were examined by histology, fluorescence in situ hybridization (FISH) and real time quantitative polymerase chain reaction (PCR). Serum was examined for anti-C. burnetii antibodies by enzyme-linked immunosorbent assay (ELISA). Results: Serology revealed that 70% of the cattle were positive for antibodies to C. burnetii, while PCR analysis identified 25% of endocarditis valve samples as being positive. C. burnetii was not detected by FISH, probably due to the low infection levels. Most cattle had chronic valvular vegetative endocarditis with lesions being characterised by a core of fibrous tissue covered by significant amounts of fibrin, sometimes with areas of liquefaction, and with a coagulum covering the surface. In a few cases, including the case with the highest infection level, lesions were characterized by extensive fibrosis and calcification. Histologically, bacteria other than C. burnetii were observed in most cases. Conclusions: The presence of C. burnetii DNA is relatively common in cattle affected with valvular endocarditis. The role of C. burnetii remains however unknown as lesions did not differ between C. burnetii infected and non-infected cattle and because T. pyogenes-like bacteria were present in the inflamed valves; a bacterium able to induce the observed lesions. Heart valves of normal cattle should be investigated to assess if C. burnetii may be present without preexisting lesions.

Targeting trichothecene biosynthetic genes
Wei, Songhong ; Lee, Theo van der; Verstappen, Els ; Gent, Marga van; Waalwijk, Cees - \ 2017
In: Mycotoxigenic Fungi Humana Press Inc. (Methods in Molecular Biology ) - ISBN 9781493967056 - p. 173 - 189.
PCR - Quantitative PCR - Trichothecenes
Biosynthesis of trichothecenes requires the involvement of at least 15 genes, most of which have been targeted for PCR. Qualitative PCRs are used to assign chemotypes to individual isolates, e.g., the capacity to produce type A and/or type B trichothecenes. Many regions in the core cluster (consisting of 12 genes) including intergenic regions have been used as targets for PCR, but the most robust assays are targeted to the tri3 and tri12 genes. Quantitative PCRs, that work across trichothecene-producing members of the Fusarium head blight complex, are described along with procedures to quantify the amount of fungal biomass in wheat samples. These assays are directed to the chemotype(s) present in field samples and quantify the total fungal biomass of trichothecene-producing fungi, irrespective of their genetic identity.
Novel TaqMan PCR screening methods for element cry3A and construct gat/T-pinII to support detection of both known and unknown GMOs
Prins, Theo W. ; Hoof, Richard A. van; Scholtens, Ingrid M.J. ; Kok, Esther J. - \ 2017
European Food Research and Technology 243 (2017)3. - ISSN 1438-2377 - p. 481 - 488.
Detection - Identification - PCR - qPCR - Real-time - Screening

The import and use of genetically modified organisms (GMOs) is strictly regulated in the European Union. In order to maintain the legislation on GMOs, a genetic element screening is generally applied as a first step to detect authorised as well as unauthorised GMOs. Subsequent identification of GMOs that relate to the detected elements is performed by the application of event-specific detection methods. However, as the diversity of GMOs on the world market is increasing, there is an ongoing need for methods for additional informative screening elements. Genes that are increasingly applied in GMOs are cry3A (including variants mcry3A and eCry3.1Ab) conferring resistance to Bt toxins, and gat, detoxifying glyphosate. Novel TaqMan PCR detection methods for element cry3A and construct gat/T-pinII were developed to support the identification of maize MIR604, 98140, 5307, canola 61061 and 73496, and soybean 356043. Also, other unknown (unauthorised) GMOs containing cry3A and/or gat/T-pinII can potentially be detected. Specificity, efficiency and sensitivity of the methods were evaluated.

Toxoplasma gondii in stranded marine mammals from the North Sea and Eastern Atlantic Ocean : Findings and diagnostic difficulties
Velde, Norbert van de; Devleesschauwer, Brecht ; Leopold, Mardik ; Begeman, Lineke ; IJsseldijk, Lonneke ; Hiemstra, Sjoukje ; IJzer, Jooske ; Brownlow, Andrew ; Davison, Nicholas ; Haelters, Jan - \ 2016
Veterinary Parasitology 230 (2016). - ISSN 0304-4017 - p. 25 - 32.
ELISA - IFA - Marine mammals - MAT - PCR - Seroprevalence - Toxoplasma gondii

The occurrence of the zoonotic protozoan parasite Toxoplasma gondii in marine mammals remains a poorly understood phenomenon. In this study, samples from 589 marine mammal species and 34 European otters (Lutra lutra), stranded on the coasts of Scotland, Belgium, France, The Netherlands and Germany, were tested for the presence of T. gondii. Brain samples were analysed by polymerase chain reaction (PCR) for detection of parasite DNA. Blood and muscle fluid samples were tested for specific antibodies using a modified agglutination test (MAT), a commercial multi-species enzyme-linked immunosorbent assay (ELISA) and an immunofluorescence assay (IFA). Out of 193 animals tested by PCR, only two harbour porpoise (Phocoena phocoena) cerebrum samples, obtained from animals stranded on the Dutch coast, tested positive. The serological results showed a wide variation depending on the test used. Using a cut-off value of 1/40 dilution in MAT, 141 out of 292 animals (41%) were positive. Using IFA, 30 out of 244 tested samples (12%) were positive at a 1/50 dilution. The commercial ELISA yielded 7% positives with a cut-off of the sample-to-positive (S/P) ratio ≥ 50; and 12% when the cut-off was set at S/P ratio ≥ 20. The high number of positives in MAT may be an overestimation due to the high degree of haemolysis of the samples and/or the presence of lipids. The ELISA results could be an underestimation due to the use of a multispecies conjugate. Our results confirm the presence of T. gondii in marine mammals in The Netherlands and show exposure to the parasite in both the North Sea and the Eastern Atlantic Ocean. We also highlight the limitations of the tests used to diagnose T. gondii in stranded marine mammals.

DNA enrichment approaches to identify unauthorized genetically modified organisms (GMOs)
Arulandhu, Alfred J. ; Dijk, Jeroen P. van; Dobnik, David ; Holst-Jensen, Arne ; Shi, Jianxin ; Zel, Jana ; Kok, Esther J. - \ 2016
Analytical and Bioanalytical Chemistry 408 (2016)17. - ISSN 1618-2642 - p. 4575 - 4593.
Enrichment approaches - GMOs - NGS - PCR - UGMOs

With the increased global production of different genetically modified (GM) plant varieties, chances increase that unauthorized GM organisms (UGMOs) may enter the food chain. At the same time, the detection of UGMOs is a challenging task because of the limited sequence information that will generally be available. PCR-based methods are available to detect and quantify known UGMOs in specific cases. If this approach is not feasible, DNA enrichment of the unknown adjacent sequences of known GMO elements is one way to detect the presence of UGMOs in a food or feed product. These enrichment approaches are also known as chromosome walking or gene walking (GW). In recent years, enrichment approaches have been coupled with next generation sequencing (NGS) analysis and implemented in, amongst others, the medical and microbiological fields. The present review will provide an overview of these approaches and an evaluation of their applicability in the identification of UGMOs in complex food or feed samples.

Prevalence of Anti-Hepatitis E Virus Antibodies and First Detection of Hepatitis E Virus in Wild Boar in Slovenia
Žele, Diana ; Fernandes Barry, Aline ; Honing-Hakze, Renate van der; Vengušt, Gorazd ; Poel, W.H.M. Van Der - \ 2016
Vector-Borne and Zoonotic Diseases 16 (2016)1. - ISSN 1530-3667 - p. 71 - 74.
Hepatitis E - Hepatitis E virus - PCR - Serology - Slovenia - Wild boar

Hepatitis E is an emerging zoonotic disease caused by hepatitis E virus (HEV). In this study, we investigated HEV presence in a wild boar (Sus scrofa) population of Slovenia. A total of 288 wild boar serum samples were collected throughout the country, and HEV infection was investigated by serology, using enzyme-linked immunosorbent assay (ELISA) and by HEV RNA detection using a real-time PCR assay. Antibodies against HEV were detected in 30.2% (87/288) of animals tested, whereas HEV RNA was detected in only one sample. This is the first evidence of HEV presence in the wild boar population in Slovenia, and these results suggest that these animals are part of the HEV epidemiological cycle in the country.

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