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 development of a multiplex serological assay for avian influenza based on Luminex technology
Germeraad, Evelien ; Achterberg, René ; Venema, Sandra ; Post, Jacob ; Leeuw, Olav de; Koch, Guus ; Wal, Fimme Jan van der; Beerens, Nancy - \ 2019
Methods : a companion to Methods in enzymology (2019). - ISSN 1046-2023
Avian influenza - Luminex - Multiplex - Poultry - Serology - Subtyping

Avian influenza (AI) is an infectious disease in birds with enormous impact on the poultry sector. AI viruses are divided into different subtypes based on the antigenicity of their surface proteins haemagglutinin (HA) and neuraminidases (NA). In birds, 16 HA subtypes and 9 NA subtypes are detected in different combinations. Traditional serological methods for the subtyping of AI antibodies are labour-intensive and have to be performed for each HA and NA subtype separately. This study describes the development of a multiplex serological assay for subtyping AI antibodies in poultry sera using Luminex xMAP technology. This multiplex assay allows the detection of all AI serotypes in one single assay. For all HA and NA subtypes, recombinant proteins were purified and coupled to colour-coded magnetic bead sets. Using the Luminex MAGPIX device, binding of serum antibodies to the antigens on the bead sets is detected by fluorescent secondary antibodies, and the different bead sets are identified. The results of the multiplex assay were compared with that of the traditional singleplex assays. We show that serotyping using the novel multiplex serological assay is consistent with the results of the traditional assays in 97.8% of the reference sera and in 90.8% of the field sera. The assay has a higher sensitivity than the traditional assays, and requires a smaller sample volume. Therefore, the assay will allow complete AI-serotyping in small volumes of field sera, which will improve the monitoring of AI subtypes circulating in poultry significantly.

Influence of Age and Dose of African Swine Fever Virus Infections on Clinical Outcome and Blood Parameters in Pigs
Post, Jacob ; Weesendorp, Eefke ; Montoya, Maria ; Loeffen, Willie L. - \ 2017
Viral Immunology 30 (2017)1. - ISSN 0882-8245 - p. 58 - 69.
African swine fever - IL-10 - peripheral blood cells - serum cytokines - γδ T cells

African swine fever (ASF) is a fatal disease for domestic pigs, leading to serious economic losses in countries where ASF is endemic. Despite extensive research, efficient vaccines against ASF are lacking. Since peripheral blood cells are important mediators for vaccines, we study the impact of ASF on blood parameters in pigs with different ages and infected with different doses of ASF virus. Four different groups were studied: (1) 12 weeks of age/low virus dose; (2) 12 weeks of age/high virus dose; (3) 18 weeks of age/low virus dose; and (4) 18 weeks of age/high virus dose. By varying in age and/or ASFV inoculation dose, we monitor blood parameters during different degrees of disease. Thirty percent of the pigs survived the infection with a moderately virulent strain of African swine fever virus (ASFV). Animals that did survive infection were generally older, independent from the inoculation dose used. A firm reduction in many different cell types at 3-5 days postinfection (DPI) was accompanied by an increase in body temperature, followed by clinical signs and mortality from day 6 PI. While blood parameters generally normalized in survivors, γδ T cells and IL-10 levels could be related to mortality. These conclusions should be considered in new approaches for protection against ASF.

The effect of C. burnetii infection on the cytokine response of PBMCs from pregnant goats
Ammerdorfer, A. ; Roest, H.I.J. ; Dinkla, A. ; Post, J. ; Schoffelen, T. ; Deuren, M. van; Sprong, T. ; Rebel, J.M.J. - \ 2014
PLoS ONE 9 (2014)10. - ISSN 1932-6203
tumor-necrosis-factor - q-fever endocarditis - t-cells - factor-alpha - gamma - interleukin-10 - interferon - mice - monocytes
In humans, infection with Coxiella burnetii, the causative agent of Q fever, leads to acute or chronic infection, both associated with specific clinical symptoms. In contrast, no symptoms are observed in goats during C. burnetii infection, although infection of the placenta eventually leads to premature delivery, stillbirth and abortion. It is unknown whether these differences in clinical outcome are due to the early immune responses of the goats. Therefore, peripheral blood mononuclear cells (PBMCs) were isolated from pregnant goats. In total, 17 goats were included in the study. Six goats remained naive, while eleven goats were infected with C. burnetii. Toll-like receptor (TLR) and cytokine mRNA expression were measured after in vitro stimulation with heat-killed C. burnetii at different time points (prior infection, day 7, 35 and 56 after infection). In naive goats an increased expression of interleukin (IL)-1ß, tumor necrosis factor (TNF)-a, IL-10 and interferon (IFN)-¿ mRNA upon C. burnetii stimulation was detected. In addition, TLR2 expression was strongly up-regulated. In goats infected with C. burnetii, PBMCs re-stimulated in vitro with C. burnetii, expressed significantly more TNF-a mRNA and IFN-¿ mRNA compared to naive goats. In contrast, IL-10 mRNA production capacity was down-regulated during C. burnetii infection. Interestingly, at day 7 after inoculation a decreased IFN-¿ protein level was observed in stimulated leukocytes in whole blood from infected goats, whereas at other time-points increased production of IFN-¿ protein was seen. Our study shows that goats initiate a robust pro-inflammatory immune response against C. burnetii in vitro. Furthermore, PBMCs from C. burnetii infected goats show augmented pro-inflammatory cytokine responses compared to PBMCs from non-infected goats. However, despite this pro-inflammatory response, goats are not capable of clearing the C. burnetii infection.
Contribution of the NS1 Gene of H7 Avian Influenza Virus Strains to Pathogenicity in Chickens
Post, J. ; Peeters, B.P.H. ; Cornelissen, J.B.W.J. ; Vervelde, L. ; Rebel, J.M.J. - \ 2013
Viral Immunology 26 (2013)6. - ISSN 0882-8245 - p. 396 - 403.
a virus - nonstructural protein-1 - cytokine responses - interferon - h5n1 - infection - virulence - cells - ducks - beta
Using reverse genetics (rg), we generated two reassortant viruses carrying the NS1 gene of two closely related HPAIV and LPAIV H7N1 variants (designated rgH7N7 HPHPNS1 and rgH7N7 HPLPNS1, respectively) in the backbone of the HP H7N7 strain A/Chicken/Netherlands/621557/03 (rgH7N7 HP). Comparison of these reassortants allowed us to determine the effect of amino acid differences in the nuclear export and nucleolar localization sequences of NS1 on pathogenesis in chickens. Compared to rgH7N7 HPLPNS1, a delay in weight gain and an increase in mortality were observed for rgH7N7 HPHPNS1. Furthermore, an increase in viral load in brains, lungs, and cloacal swabs, as well as an increased induction of mRNA for type I interferons and proinflammatory cytokines in brains, were observed for rgH7N7 HPHPNS1. Comparison of rgH7N7 HPLPNS1 with the backbone strain rgH7N7 HP allowed us to examine differences in pathogenesis due to differences in NS1 alleles. rgH7N7 HP, which contained allele A of NS1 showed a higher in vitro replication rate and proved to be more virulent than the isogenic virus carrying allele B of NS1(rgH7N7 HPLPNS1). In addition, higher virus accumulation in the lungs and brains, and an increased induction of host gene responses, especially in the brains, were found for rgH7N7 HP compared to rgH7N7 HPLPNS1. No large differences were observed in type I interferon expression in the lungs of chickens infected with any of the viruses, suggesting that differences in virulence due to differences in NS1 could be related to differences in the induction of pro-inflammatory cytokines in vital organs such as the brains.
Q fever in pregnant goats: humoral and cellular immune responses
Roest, H.I.J. ; Post, J. ; Gelderen, E. van; Zijderveld, F.G. van; Rebel, J.M.J. - \ 2013
Veterinary Research 44 (2013)1. - ISSN 0928-4249 - 9 p.
coxiella-burnetii infection - phase-i - t-cells - netherlands - outbreak - mice - lipopolysaccharide - progesterone - vaccination - history
Q fever is a zoonosis caused by the intracellular bacterium Coxiella burnetii. Both humoral and cellular immunity are important in the host defence against intracellular bacteria. Little is known about the immune response to C. burnetii infections in domestic ruminants even though these species are the major source of Q fever in humans. To investigate the goat’s immune response we inoculated groups of pregnant goats via inhalation with a Dutch outbreak isolate of C. burnetii. All animals were successfully infected. Phase 1 and Phase 2 IgM- and IgG-specific antibodies were measured. Cellular immune responses were investigated by interferon-gamma, enzyme-linked immunosorbent spot test (IFN-¿ Elispot), lymphocyte proliferation test (LPT) and systemic cytokines. After two weeks post inoculation (wpi), a strong anti-C. burnetii Phase 2 IgM and IgG antibody response was observed while the increase in IgM anti-Phase 1 antibodies was less pronounced. IgG anti-Phase 1 antibodies started to rise at 6 wpi. Cellular immune responses were observed after parturition. Our results demonstrated humoral and cellular immune responses to C. burnetii infection in pregnant goats. Cell-mediated immune responses did not differ enough to distinguish between Coxiella-infected and non-infected pregnant animals, whereas a strong-phase specific antibody response is detected after 2 wpi. This humoral immune response may be useful in the early detection of C. burnetii-infected pregnant goats.
Differences in highly pathogenic avian influenza viral pathogenesis and associated early inflammatory response in chickens and ducks
Cornelissen, J.B.W.J. ; Vervelde, L. ; Post, J. ; Rebel, J.M.J. - \ 2013
Avian Pathology 42 (2013)4. - ISSN 0307-9457 - p. 347 - 364.
activated protein-kinase - innate immune-responses - toll-like receptor-7 - a virus-infection - anas-platyrhynchos - pekin ducks - h5n1 influenza - cytokine responses - domestic ducks - tissue tropism
We studied the immunological responses in the lung, brain and spleen of ducks and chickens within the first 7 days after infection with H7N1 highly pathogenic avian influenza (HPAI). Infection with HPAI caused significant morbidity and mortality in chickens, while in ducks the infection was asymptomatic. The HPAI viral mRNA load was higher in all investigated tissues of chickens compared with duck tissues. In the lung, brain and spleen of HPAI-infected chickens, a high, but delayed, pro-inflammatory response of IL-6 and IL-1ß mRNA was induced, including up-regulation of IFN-ß, IFN-¿, TLR3 and MDA-5 mRNA from 1 day post infection (p.i.). Whereas in ducks already at 8 h p.i., a quicker but lower response was found for IL-6, IL-1ß and iNOS mRNA followed by a delayed activation of TLR7, RIG-I, MDA5 and IFN-¿ mRNA response. Virus-infected areas in the lung of chickens co-localized with KUL-01¿ (macrophages, dendritic cells), CD4¿, and CD8a¿ cells, during the first day after infection. However, only KUL-01¿ cells co-localized with the virus after 1 day p.i. In ducks, CVI-ChNL-68.1¿ (macrophage-like cells), CD4¿ and CD8a¿ cells and apoptosis co-localized with the virus within 8 h p.i. Apoptosis was detected in the brain and lung of HPAI-infected chickens after 2 days p.i. and apoptotic cells co-localized with virus-infected areas. In conclusion, excessive delayed cytokine inflammatory responses but inadequate cellular immune responses may contribute to pathogenesis in chickens, while ducks initiate a fast lower cytokine response followed by the activation of major pattern recognition receptors (TLR7, RIG-I, MDA5) and a persistent cellular response.
Systemic distribution of different low pathogenic avian influenza (LPAI) viruses in chicken
Post, J. ; Geus, E.D. ; Vervelde, L. ; Cornelissen, J.B.W.J. ; Rebel, J.M.J. - \ 2013
Virology journal 10 (2013). - ISSN 1743-422X - 7 p.
h9n2 - turkeys - infection - evolution - poultry - h7 - h5
Background Since we were able to isolate viable virus from brain and lung of H7N1 low pathogenic avian influenza virus (LPAIV) infected chickens, we here examined the distribution of different LPAIV strains in chickens by measuring the viral AI RNA load in multiple organs. Subtypes of H5 (H5N1, H5N2), H7 (H7N1, H7N7) and H9 (H9N2), of chicken (H5N2, H7N1, H7N7, H9N2), or mallard (H5N1) origin were tested. The actual presence of viable virus was evaluated with virus isolation in organs of H7N7 inoculated chickens. Findings Viral RNA was found by PCR in lung, brain, intestine, peripheral blood mononuclear cells, heart, liver, kidney and spleen from chickens infected with chicken isolated LPAIV H5N2, H7N1, H7N7 or H9N2. H7N7 virus could be isolated from lung, ileum, heart, liver, kidney and spleen, but not from brain, which was in agreement with the data from the PCR. Infection with mallard isolated H5N1 LPAIV resulted in viral RNA detection in lung and peripheral blood mononuclear cells only. Conclusion We speculate that chicken isolated LPAI viruses are spreading systemically in chicken, independently of the strain.
Chicken dendritic cells are susceptible to highly pathogenic avian influenza viruses which induce strong cytokine responses
Vervelde, L. ; Reemens, S.S. ; Haarlem, D.A. van; Post, J. ; Claassen, E.A.W. ; Rebel, J.M.J. ; Jansen, C.A. - \ 2013
Developmental and Comparative Immunology 39 (2013)3. - ISSN 0145-305X - p. 198 - 206.
ns1 protein - a virus - swine influenza - gene-expression - infection - interferon - activation - pathobiology - recognition - inhibition
Infection with highly pathogenic avian influenza (HPAI) in birds and mammals is associated with severe pathology and increased mortality. We hypothesize that in contrast to low pathogenicity avian influenza (LPAI) infection, HPAI infection of chicken dendritic cells (DC) induces a cytokine deregulation which may contribute to their highly pathogenic nature. Infection of DC with LPAI H7N1 and H5N2 resulted in viral RNA and NP expression without increase in time, in contrast to HPAI H7N1 and H5N2 mRNA expression. No increase in IFN mRNA was detected after infection with LPAI, but after LPAI H5N2, and not LPAI H7N1, infection the level of bioactive IFNa/ß significantly increased. After HPAI H7N1 and H5N2 infection, significant increases in IL-8, IFN-a, IFN-¿ mRNA expression and in TLR1, 3, and 21 mRNA were observed. This enhanced activation of DC after HPAI infection may trigger deregulation of the immune response as seen during HPAI infection in chickens.
Comparison of cytokine responses in goats after stimulations with different Coxiella strains
Ammerdorffer, A. ; Dinkla, A. ; Post, J. ; Joosten, K. ; Netea, M.G. ; Rebel, J.M.J. ; Sprong, T. ; Roest, H.I.J. - \ 2012
Systemic Virus distribution and host responses in brain and intestine of chickens infected with low pathogenic and high pathogenic avian influenza virus
Post, J. ; Burt, D.W. ; Cornelissen, J.B.W.J. ; Broks, V.C.M. ; Zoelen, D. van; Peeters, B.P.H. ; Rebel, J.M.J. - \ 2012
Virology journal 9 (2012). - ISSN 1743-422X - 14 p.
hemagglutinin cleavage site - membrane-fusion - pekin ducks - a viruses - h5n1 - pathology - pathobiology - replication - chemokines - antibodies
Background: Avian influenza virus (AIV) is classified into two pathotypes, low pathogenic (LP) and high pathogenic ( HP), based on virulence in chickens. Differences in pathogenicity between HPAIV and LPAIV might eventually be related to specific characteristics of strains, tissue tropism and host responses. Methods: To study differences in disease development between HPAIV and LPAIV, we examined the first appearance and eventual load of viral RNA in multiple organs as well as host responses in brain and intestine of chickens infected with two closely related H7N1 HPAIV or LPAIV strains. Results: Both H7N1 HPAIV and LPAIV spread systemically in chickens after a combined intranasal/intratracheal inoculation. In brain, large differences in viral RNA load and host gene expression were found between H7N1 HPAIV and LPAIV infected chickens. Chicken embryo brain cell culture studies revealed that both HPAIV and LPAIV could infect cultivated embryonic brain cells, but in accordance with the absence of the necessary proteases, replication of LPAIV was limited. Furthermore, TUNEL assay indicated apoptosis in brain of HPAIV infected chickens only. In intestine, where endoproteases that cleave HA of LPAIV are available, we found minimal differences in the amount of viral RNA and a large overlap in the transcriptional responses between HPAIV and LPAIV infected chickens. Interestingly, brain and ileum differed clearly in the cellular pathways that were regulated upon an AI infection. Conclusions: Although both H7N1 HPAIV and LPAIV RNA was detected in a broad range of tissues beyond the respiratory and gastrointestinal tract, our observations indicate that differences in pathogenicity and mortality between HPAIV and LPAIV could originate from differences in virus replication and the resulting host responses in vital organs like the brain.
Diffferential innate responses of chickens and ducks to low pathogenic avian influenza virus
Cornelissen, J.B.W.J. ; Post, J. ; Peeters, B.P.H. ; Vervelde, L. ; Rebel, J.M.J. - \ 2012
Avian Pathology 41 (2012)6. - ISSN 0307-9457 - p. 519 - 529.
toll-like receptor-7 - a virus-infection - rig-i - gene-expression - target-cells - ifn-beta - recognition - h9n2 - replication - h5n1
Ducks and chickens are hosts of avian influenza virus, each with distinctive responses to infection. To understand these differences, we characterized the innate immune response to low pathogenicity avian influenza virus H7N1 infection in chickens and ducks. Viral RNA was detected in the lungs of chickens from day 0.8 to 7, in ducks mainly at day 4. In both species viral RNA was detected in the bursa and gut. Infection in chickens resulted in up-regulation of interferon (IFN)-a and IFN-ß mRNA, while in the ducks IFN-¿ mRNA was strongly up-regulated in lung and bursa. In chickens and ducks all investigated pathogen recognition receptors (PRR) mRNA were up regulated, however, in the chicken lung Toll-like receptor (TLR)7 and melanoma differentiation-associated protein (MDA)-5 mRNA were strongly induced. TLR3, TLR7 and MDA-5 responses correlated with IFN-a and IFN-ß responses in chickens, but in ducks a correlation between IFN-a and TLR7, retinoic acid-inducible gene-I and MDA-5 was absent. We studied the responses of duck and chicken splenocytes to poly (I:C) and R848 analogues to analyze the regulation of PRRs without the interfering mechanisms of the influenza virus. This revealed IFN-a and IFN- ¿ responses in both species. MDA-5 was only strongly up-regulated in chicken splenocytes. In chickens splenocytes, time related PRR responses correlated with the IFN-a and IFN-ß response. In duck splenocytes this correlation was absent. In conclusion, chicken and duck differ in induction of MDA-5, TLR7 and IFN-a mRNA after an influenza virus infection in vivo and after in vitro stimulation with TLR antagonists.
Highly pathogenic or low pathogenic avian influenza virus subtype H7N1 infection in chicken lungs: small differences in general acute responses.
Rebel, J.M.J. ; Peeters, B.P.H. ; Fijten, H.P.D. ; Post, J. ; Cornelissen, J.B.W.J. ; Vervelde, L. - \ 2011
Veterinary Research 42 (2011). - ISSN 0928-4249 - 11 p.
cytokine responses - respiratory-tract - a virus - immune-responses - host-responses - h5n1 virus - cells - expression - deposition - h9n2
Avian influenza virus can be divided into two groups, highly pathogenic avian influenza virus (HPAI) and low pathogenic avian influenza virus (LPAI) based on their difference in virulence. To investigate if the difference in clinical outcome between LPAI and HPAI in chickens is due to immunological host responses in the lung within the first 24 hours post infection (hpi), chickens were infected with LPAI or HPAI of subtype H7N1. Virus was found in the caudal and cranial part of the lung. With LPAI, virus was localised around the intrapulmonary bronchus and secondary bronchi. In sharp contrast, HPAI was detected throughout the whole lung. However, based on viral RNA levels, no quantitative difference was observed between LPAI and HPAI infected birds. In infected areas of the lungs, an influx of CD8a+ cells as well as KUL01+ macrophages and dendritic cells (DC) occurred as fast as 8 hpi in both infected groups. No major difference between LPAI and HPAI infected birds in the induction of cytokines and interferons at mRNA level in lung tissue was found. In conclusion, the differences in lethality for chickens infected with LPAI or HPAI could be ascribed to difference in location of the virus. However similar amounts of viral RNA, similar cytokine mRNA levels, and similar influxes of CD8a+ and KUL01+ macrophages and DC were found between HPAI and LPAI in the lungs. A cytokine storm at mRNA level as described for mammals was not observed in the lungs of HPAI infected birds within 24 hpi.
Differences in host response and virus replication in chickens infected with low pathogenic of high pathogenic avian influenza viruses
Post, J. ; Cornelissen, J.B.W.J. ; Burt, D.W. ; Broks, V.C.M. ; Zoelen, D. van; Peeters, B. ; Rebel, J.M.J. - \ 2010
Immune reaction in chickens and ducks inn response to low pathogenic avian Influenza
Cornelissen, J.B.W.J. ; Post, J. ; Peeters, B. ; Fijten, H.P.D. ; Vervelde, L. ; Rebel, J.M.J. - \ 2010
The potential of blue energy for reducing emissions of CO2 and non-CO2 greenhouse gases
Kuleszo, J. ; Kroeze, C. ; Post, J. ; Fekete, B.M. - \ 2010
Journal of integrative Environmental Sciences 7 (2010)S1. - ISSN 1943-815X - p. 89 - 96.
Salinity gradient power (or blue energy) is a renewable energy source mentioned in the literature since the 1950s. It refers to the production of electricity by mixing of two solutions with different salt concentrations, for example river and sea water. The global potential of salinity power has been estimated in the 1970s as substantial, but the state of membrane technology at that time - crucial for energy recovery - did not permit the practical use of this resource. More recently, the interest in salinity power has been growing because of the need for carbon neutral, renewable sources of electricity. This study aims to assess the potential of salinity-gradient power for reducing emissions of CO2 and non-CO2 greenhouse gases. First, we discuss the global technical potential for blue energy, i.e. the maximum amount of energy that could be retrieved at the current state of technology. We focus on rivers as source of fresh water and seas as source of saline water. The analysis is based on global datasets of annual river discharges for more than 5000 world rivers. The resulting estimates of global and regional potentials for salinity gradient power are used to estimate the potential for reducing greenhouse gases, assuming that salinity power would reduce the need for fossil fuels. The results are shown for global totals, regional totals and selected rivers.
The Potential of Blue Energy to Reduce Emissions of CO2 and non-CO2 Greenhouse Gases
Kuleszo, J. ; Kroeze, C. ; Post, J. - \ 2010
Detection probability of Campylobacter
Evers, E.G. ; Post, J. ; Putirulan, F.F. ; Wal, F.J. van der - \ 2010
Food Control 21 (2010)3. - ISSN 0956-7135 - p. 247 - 252.
A rapid presence/absence test for Campylobacter in chicken faeces is being evaluated to support the scheduling of highly contaminated broiler flocks as a measure to reduce public health risks [Nauta, M. J., & Havelaar, A. H. (2008). Risk-based standards for Campylobacter in the broiler meat chain. Food Control, 19, 372–381]. Although the presence/absence test is still under development, an example data set of test results is analysed to illustrate the benefit of the detection probability concept. The detection probability of Campylobacter increases with the logarithm of the Campylobacter concentration in faeces according to an S-shaped curve which stretches about 2–3 log units. The detection probability is 50% at a Campylobacter concentration of 7.4 × 106 cfu/g. The uncertainty in the detection probability is 32% at the most for a 90% confidence interval. This type of information allows for realistic calculations on the Campylobacter status of different food processing paths after splitting. Usable quantitative estimates on detection probability await a data set of test results from a test that is ready for use or has similar properties
Differences in immune reaction between chicken and ducks in response to low pathogenic avian influenza
Cornelissen, J.B.W.J. ; Post, J. ; Peeters, B. ; Fijten, H.P.D. ; Vervelde, L. ; Rebel, J.M.J. - \ 2009
Highly pathogenic or low pathogenic avian influenza virus subtype H7N1 infection in chicken lungs: small differences amidst general acute responses
Rebel, J.M.J. ; Peeters, B. ; Fijten, H.P.D. ; Post, J. ; Cornelissen, J.B.W.J. ; Hoek, A. ; Vervelde, L. - \ 2009
Evaluation of the " testing and scheduling" strategy for control of Campylobacter in broilers in The Netherlands
Nauta, M.J. ; Wal, F.J. van der; Putirulan, F.F. ; Post, J. ; Kassteele, J. van de; Bolder, N.M. - \ 2009
International Journal of Food Microbiology 134 (2009)3. - ISSN 0168-1605 - p. 216 - 222.
quantitative risk-assessment - real-time pcr - cross-contamination - chicken carcasses - poultry carcasses - spp. - numbers - quantification - prevalence - chain
“Testing and scheduling” has been proposed as a strategy for control of Campylobacter in broiler meat. By this strategy, flocks with high numbers of Campylobacter in fecal samples would be diverted away from fresh meat production at the entrance of the broiler meat processing plant. Risk assessment studies suggest that this would effectively decrease human health risks, if these flocks are responsible for the meat products with the highest Campylobacter numbers. To investigate the effect of this control strategy, the numbers of Campylobacter were determined in fecal samples from transport containers, and in cecal and breast meat samples from birds in 62 broiler chicken flocks. Results from direct plating and enrichment were combined by a statistical method that allows the inclusion of censored data. As the implementation of “testing and scheduling” requires a rapid on-site test to detect high numbers of Campylobacter, a lateral flow immuno-assay (LFA) was developed and applied to the fecal samples collected from containers. The Campylobacter prevalence in broiler flocks in the autumn of 2007 was found to be 85.4% by traditional microbiological methods. Campylobacter could be isolated from breast meat samples from 42% of the flocks. There was limited agreement between Campylobacter results for the three types of samples and weak correlation between the quantitative results for fecal or cecal samples and meat samples. Agreement between the results of LFA and traditional methods was poor. These findings do not support the implementation of “testing and scheduling” as a practical control strategy, because of both measurement uncertainties and shortcomings in understanding the dynamics of transmission and survival of Campylobacter in the broiler meat processing plant. The limited correlation between Campylobacter contamination of cecal samples and breast meat samples, as observed in this study, suggests that cecal samples are no good indicator for human exposure to Campylobacter.
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