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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Mycobacterium avium Subspecies paratuberculosis DNA and Antobodies in Dairy Goat Colostrum and Milk
Lievaart-Peterson, Karianne ; Luttikholt, S. ; Gonggrijp, Maaike ; Ruuls, R.C. ; Ravesloot, Lars ; Koets, A.P. - \ 2019
Veterinary Sciences 6 (2019)4. - ISSN 2306-7381
Mycobacterium avium subspecies paratuberculosis (MAP) is endemic in the Dutch dairy goat population causing economic loss, and negatively influencing welfare. Moreover, there are concerns about a potential zoonotic risk. Therefore the industry’s objectives are to decrease MAP prevalence, limit economic losses as well as reduce the concentration of MAP in (bulk) milk. To diminish within-farm spread of infection, vaccination, age dependent group housing with separation of newborns from adults, as well as rearing on artificial or treated colostrum and milk replacers are implemented. However, the importance of MAP contaminated colostrum and milk as a route of infection in dairy goat herds is unknown. Therefore the aim of this study was to detect the presence of MAP DNA in colostrum and milk from dairy goats in infected herds. A convenience sample of 120 colostrum samples and 202 milk samples from MAP infected dairy goat herds were tested by IS900 real-time Polymerase Chain Reaction (PCR) for MAP DNA. Furthermore, 22 colostrum samples and 27 post mortem milk samples of goats with clinical signs consistent with paratuberculosis from known infected herds were tested. The majority of samples were from goats vaccinated against MAP. Positive or doubtful PCR results were obtained in none of the 120 and two of the 22 colostrum samples, and in eight of the 202 and four of the 27 milk samples Negative PCR results were obtained in the remaining 140 (99%) colostrum samples and 217 (95%) milk samples.
Effects of age and environment on adaptive immune responses to Mycobacterium avium subsp. paratuberculosis (MAP) vaccination in dairy goats in relation to paratuberculosis control strategies
Koets, Ad ; Ravesloot, Lars ; Ruuls, Robin ; Dinkla, Annemieke ; Eisenberg, Susanne ; Lievaart-Peterson, Karianne - \ 2019
Veterinary Sciences 6 (2019)3. - ISSN 2306-7381
Diagnostics - Immunity - Mycobacterium - Paratuberculosis - Vaccination

Paratuberculosis infection is caused by Mycobacterium avium subsp. paratuberculosis (MAP). In the Netherlands, 75% herd level prevalence of caprine paratuberculosis has been estimated, and vaccination is the principal control strategy applied. Most goat dairy farms with endemic paratuberculosis systematically vaccinate goat kids in the first months of life with a commercially available whole cell MAP vaccine. We hypothesized that the development of adaptive immune responses in goats vaccinated at young age depends on the environment they are raised in, and this has implications for the application of immune diagnostic tests in vaccinated dairy goats. We evaluated the early immune response to vaccination in young goat kids sourced from a MAP unsuspected non-vaccinated herd and raised in a MAP-free environment. Subsequently we compared these with responses observed in birth year and vaccination matched adult goats raised on farms with endemic paratuberculosis. Results indicated that initial adaptive immune responses to vaccination are limited in a MAP-free environment. In addition, adult antibody positive vaccinated goats raised in a MAP endemic environment are less likely to be IS900 PCR-positive as compared to antibody negative herd mates. We conclude that test-and-cull strategies in a vaccinated herd are currently not feasible using available immune diagnostic tests.

Effect of dietary phosphorus deprivation on leukocyte function in transition cows
Eisenberg, S.W.F. ; Ravesloot, L. ; Koets, A.P. ; Grünberg, W. - \ 2019
Journal of Dairy Science 102 (2019)2. - ISSN 0022-0302 - p. 1559 - 1570.
hypophosphatemia - immune function - lymphoproliferation test - phagocytosis assay

Phosphorus depletion and hypophosphatemia have been described to hamper immune function in different species, an effect barely studied in dairy cows commonly developing hypophosphatemia in early lactation. Dietary P deprivation in mid lactating dairy cows was associated with a decline of the number of granulocytes and impaired granulocyte survival, whereas the phagocytic activity remained unaffected. The objective of the study reported here was to determine the effect of P deprivation on the leukocyte function of periparturient dairy cows. Eighteen multiparous and late pregnant dairy cows were randomly assigned to either a treatment group that was offered a markedly P-deficient diet or a control group receiving the same ration with adequate P content. The study consisted of a 2-wk acclimation period that was followed by a P deprivation period extending from 4 wk before to 4 wk after parturition and a P repletion period of 2 wk thereafter. Blood samples for leukocyte counts and leukocyte function analysis were obtained at the end of the acclimation period, after 2 wk of P deprivation, within the first week of lactation, at the end of the P depletion period and after 2 wk of dietary P supplementation. Blood samples for biochemical analysis were obtained weekly. Immune function was assessed by means of a phagocytosis assay and a lymphocyte stimulation test. Dietary P deprivation resulted in pronounced and sustained hypophosphatemia. Time effects were observed on the counts of different leukocyte fractions, the relative number of phagocytic granulocytes, the degree of phagocytosis, and the lymphocyte proliferation. Differences between P-deprived and control cows were only identified for the degree of phagocytosis that was lower in P-deprived cows compared with control cows. The correlation and regression analyses, however, revealed positive associations of the plasma phosphate concentration and the granulocyte count, the relative number of phagocytic granulocytes, and the degree of phagocytosis at the end of the dietary P deprivation when P depletion was most severe. The results of the study reported here indicate a mild negative effect of pronounced and sustained hypophosphatemia on the granulocyte count and the phagocytic activity of granulocytes in transition dairy cows. The clinical relevance of this effect for health and productivity of dairy cows remains to be determined.

Immunization of young heifers with staphylococcal immune evasion proteins before natural exposure to Staphylococcus aureus induces a humoral immune response in serum and milk
Benedictus, Lindert ; Ravesloot, Lars ; Poppe, Kim ; Daemen, Ineke ; Boerhout, Eveline ; Strijp, Jos Van; Broere, Femke ; Rutten, Victor ; Koets, Ad ; Eisenberg, Susanne - \ 2019
BMC Veterinary Research 15 (2019)1. - ISSN 1746-6148
Cattle - Efb - Experimental immunization - LukM - Mastitis - Milk antibodies - Natural exposure - Non-protective immunity - Staphylococcus aureus

Background: Staphylococcus aureus, a leading cause of mastitis in dairy cattle, causes severe mastitis and/or chronic persistent infections with detrimental effects on the cows' wellbeing, lifespan and milk production. Despite years of research there is no effective vaccine against S. aureus mastitis. Boosting of non-protective pre-existing immunity to S. aureus, induced by natural exposure to S. aureus, by vaccination may interfere with vaccine efficacy. The aim was to assess whether experimental immunization of S. aureus naïve animals results in an immune response that differs from immunity following natural exposure to S. aureus. Results: First, to define the period during which calves are immunologically naïve for S. aureus, Efb, LukM, and whole-cell S. aureus specific serum antibodies were measured in a cohort of newborn calves by ELISA. Rising S. aureus specific antibodies indicated that from week 12 onward calves mounted an immune response to S. aureus due to natural exposure. Next, an experimental immunization trial was set up using 8-week-old heifer calves (n = 16), half of which were immunized with the immune evasion molecules Efb and LukM. Immunization was repeated after one year and before parturition and humoral and cellular immunity specific for Efb and LukM was determined throughout the study. Post-partum, antibody levels against LukM and EfB were significantly higher in serum, colostrum and milk in the experimentally immunized animals compared to animals naturally exposed to S. aureus. LukM specific IL17a responses were also significantly higher in the immunized cows post-partum. Conclusions: Experimental immunization with staphylococcal immune evasion molecules starting before natural exposure resulted in significantly higher antibody levels against Efb and LukM around parturition in serum as well as the site of infection, i.e. in colostrum and milk, compared to natural exposure to S. aureus. This study showed that it is practically feasible to vaccinate S. aureus naïve cattle and that experimental immunization induced a humoral immune response that differed from that after natural exposure only.

Age-related distribution and dynamics of T-cells in blood and lymphoid tissues of goats
Baliu-Piqué, Mariona ; Kurniawan, Henry ; Ravesloot, Lars ; Verheij, Myrddin W. ; Drylewicz, Julia ; Lievaart-Peterson, Karianne ; Borghans, José A.M. ; Koets, Ad ; Tesselaar, Kiki - \ 2019
Developmental and Comparative Immunology 93 (2019). - ISSN 0145-305X - p. 1 - 10.
Deuterium - Development - Goat - Mathematical modelling - Neonatal adaptive immunity - Stable isotope labelling - T-cell turnover - T-lymphocytes

Neonatal mammals have increased disease susceptibility and sub-optimal vaccine responses. This raises problems in both humans and farm animals. The high prevalence of paratuberculosis in goats and the lack of an effective vaccine against it have a strong impact on the dairy sector, and calls for vaccines optimized for the neonatal immune system. We characterized the composition of the T-cell pool in neonatal kids and adult goats and quantified their turnover rates using in vivo deuterium labelling. From birth to adulthood, CD4+ T-cells were the predominant subset in the thymus and lymph nodes, while spleen and bone marrow contained mainly CD8+ lymphocytes. In blood, CD4+ T-cells were the predominant subset during the neonatal period, while CD8+ T-cells predominated in adults. We observed that thymic mass and cellularity increased during the first 5 months after birth, but decreased later in life. Deuterium labelling revealed that T-cell turnover rates in neonatal kids are considerably higher than in adult animals.

Short lifespans of memory T-cells in bone marrow, blood, and lymph nodes suggest that T-cell memory is maintained by continuous self-renewal of recirculating cells
Baliu-Piqué, Mariona ; Verheij, Myrddin W. ; Drylewicz, Julia ; Ravesloot, Lars ; Boer, Rob J. de; Koets, Ad ; Tesselaar, Kiki ; Borghans, José A.M. - \ 2018
Frontiers in Immunology 9 (2018)SEP. - ISSN 1664-3224
Bone marrow - Deuterium - Lifespan - Lymphocyte turnover - Mathematical modeling - Memory T-cells - Stable isotope labeling

Memory T-cells are essential to maintain long-term immunological memory. It is widely thought that the bone marrow (BM) plays an important role in the long-term maintenance of memory T-cells. There is controversy however on the longevity and recirculating kinetics of BM memory T-cells. While some have proposed that the BM is a reservoir for long-lived, non-circulating memory T-cells, it has also been suggested to be the preferential site for memory T-cell self-renewal. In this study, we used in vivo deuterium labeling in goats to simultaneously quantify the average turnover rates-and thereby expected lifespans-of memory T-cells from BM, blood and lymph nodes (LN). While the fraction of Ki-67 positive cells, a snapshot marker for recent cell division, was higher in memory T-cells from blood compared to BM and LN, in vivo deuterium labeling revealed no substantial differences in the expected lifespans of memory T-cells between these compartments. Our results support the view that the majority of memory T-cells in the BM are self-renewing as fast as those in the periphery, and are continuously recirculating between the blood, BM, and LN.

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