Bos, Jan H; Klip, Fokko C; Sprong, Hein; Broens, Els M; Kik, Marja J L (2017-08)
From a herd of captive reindeer (Rangifer tarandus tarandus) consisting of two males and seven females with five calves, three calves were diagnosed on post mortem examination with a Babesia capreoli infection. The diagnosis was indicated by PCR and when the other reindeer were examined two adult females and a one-year-old male were Babesia-positive. Molecular characterization of the 18S rDNA of the parasite showed complete identity with known B. capreoli sequences. Ixodes ricinus has been demonstrated to be a competent vector for B. capreoli from infected roe deer (Capreolus capreolus), the natural host of B. capreoli. The B. capreoli infection in these reindeer may have been transmitted by infected ticks (Ixodes ricinus) originating from roe deer living in the forest and meadows surrounding the enclosure.
Vlaanderen, J J; Janssen, N A; Hoek, G; Keski-Rahkonen, P; Barupal, D K; Cassee, F R; Gosens, I; Strak, M; Steenhof, M; Lan, Q; et al. (2017-07)
Biological perturbations caused by air pollution might be reflected in the compounds present in blood originating from air pollutants and endogenous metabolites influenced by air pollution (defined here as part of the blood metabolome). We aimed to assess the perturbation of the blood metabolome in response to short term exposure to air pollution.
We need greater understanding of the mechanisms underlying protection against influenza virus to develop more effective vaccines. To do this, we need better, more reproducible methods of sampling the nasal mucosa. The aim of the current study was to compare levels of influenza virus A subtype-specific IgA collected using three different methods of nasal sampling. Samples were collected from healthy adult volunteers before and after LAIV immunization by nasal wash, flocked swabs and Synthetic Absorptive Matrix (SAM) strips. Influenza A virus subtype-specific IgA levels were measured by haemagglutinin binding ELISA or haemagglutinin binding microarray and the functional response was assessed by microneutralization. Nasosorption using SAM strips lead to the recovery of a more concentrated sample of material, with a significantly higher level of total and influenza H1-specific IgA. However, an equivalent percentage of specific IgA was observed with all sampling methods when normalized to the total IgA. Responses measured using a recently developed antibody microarray platform, which allows evaluation of binding to multiple influenza strains simultaneously with small sample volumes, were compared to ELISA. There was a good correlation between ELISA and microarray values. Material recovered from SAM strips was weakly neutralizing when used in an in vitro assay, with a modest correlation between the level of IgA measured by ELISA and neutralization, but a greater correlation between microarray-measured IgA and neutralizing activity. In conclusion we have tested three different methods of nasal sampling and show that flocked swabs and novel SAM strips are appropriate alternatives to traditional nasal washes for assessment of mucosal influenza humoral immunity.
Blom, Maartje; Pico-Knijnenburg, Ingrid; Sijne-van Veen, Marja; Boelen, Anita; Bredius, Robbert G M; van der Burg, Mirjam; Schielen, Peter C J I (2017-07)
Newborn screening of severe combined immunodeficiency through the detection of T-cell receptor excision circles will provide the opportunity of treating before the occurrence of life-threatening infections. With the EnLite Neonatal TREC assay (PerkinElmer) and end-point PCR, 39 samples (3.0%) of 1295 heel prick cards of the Dutch newborn screening program required a retest after initial analysis. After retest, 21 samples (1.62%) gave TREC levels below cut-off. A significant reduction in TREC levels was observed in heel prick cards stored for three months (n=33) and one year (n=33). Preterm newborns (n=155) showed significantly lower TREC levels and a higher retest-rate than full-term newborns. Peripheral blood spots of 22 confirmed SCID patients and 17 primary immunodeficiency patients showed undetectable or low TREC-levels. These findings suggest that the EnLite Neonatal TREC assay is a suitable method for SCID-screening in the Netherlands, thereby providing guidance in the decisions concerning implementation into the Dutch program.
The human pathogens Borrelia afzelii, which causes Lyme borreliosis and B. miyamotoi, which causes relapsing fever, both circulate between Ixodes ricinus ticks and rodents. The spatiotemporal dynamics in the prevalence of these pathogens have not yet been fully elucidated, but probably depend on the spatiotemporal population dynamics of small rodents. We aimed to evaluate the effect of different forest types on the density of infected nymphs in different years and to obtain more knowledge about the spatial and temporal patterns of ticks and tick-borne pathogens. We analysed unfed nymphal ticks from 22 stands of four different forest types in Belgium in 2009, 2010, 2013 and 2014 and found that the density of nymphs in general and the density of nymphs infected with B. afzelii and B. miyamotoi varied yearly, but without temporal variation in the infection prevalence. The yearly variation in density of infected nymphs in our study thus seems to be caused most by the variation in the density of nymphs, which makes it a good predictor of disease risk. The risk for rodent-associated tick-borne diseases also varied between forest types. We stress the need to elucidate the contribution of the host community composition to tick-borne disease risk.
Strak, Maciej; Janssen, Nicole; Beelen, Rob; Schmitz, Oliver; Vaartjes, Ilonca; Karssenberg, Derek; van den Brink, Carolien; Bots, Michiel L; Dijst, Martin; Brunekreef, Bert; et al. (2017-11)
The evidence from observational epidemiological studies of a link between long-term air pollution exposure and diabetes prevalence and incidence is currently mixed. Some studies found the strongest associations of diabetes with fine particles, other studies with nitrogen dioxide and some studies found no associations.
Schares, G; Bangoura, B; Randau, F; Goroll, T; Ludewig, M; Maksimov, P; Matzkeit, B; Sens, M; Bärwald, A; Conraths, F J; et al. (2017-10)
Serological assays are commonly used to determine the prevalence of Toxoplasma gondii infection in livestock, but the predictive value of seropositivity with respect to the presence of infective tissue cysts is less clear. The present study aimed at the identification of seropositive and seronegative free-range laying hens from organic and backyard farms, and the relationship with the presence of viable tissue cysts. In addition, potential risk and protective factors on the selected farms were investigated. An in-house T. gondii surface antigen (TgSAG1, p30, SRS29B) ELISA was validated with sera from experimentally infected chickens and used to examine 470 serum samples collected from laying hens from large organic and small backyard farms at the end of their laying period. A total of 11.7% (55/470) of all chickens tested positive, and another 18.9% (89/470) of test results were inconclusive. The highest seroprevalences were observed on small backyard farms with 47.7% (41/86) of chickens being seropositive while another 20.9% (18/86) of test results were inconclusive. Twenty-nine seropositive, 20 seronegative and 12 laying hens which yielded inconclusive ELISA results, were selected for further examination. Hearts and limb muscles of these hens were examined for T. gondii tissue cysts in a bioassay with IFNɣ-knockout or IFNɣ-receptor-knockout mice. Viable T. gondii was isolated from 75.9% (22/29) of the seropositive, 25.0% (3/12) of the inconclusive, and 5.0% (1/20) of the seronegative chickens. All 26 chickens tested positive in heart samples, while drumstick muscles (i.e. limb muscles) tested positive only in three. Data on putative risk and protective factors were collected on the farms using a standard questionnaire. Generalised multilevel modelling revealed farm size, cat related factors ('cats on the premise', 'cats used for rodent control'), hen house/hall related factors ('size category of hen house/hall', 'frequency category of cleaning hen house/hall', 'service period') as significantly associated with seropositivity to T. gondii in hens. The final model, which included the age of the birds as an effect modifier and farm as a random effect variable, revealed that the use of cats for rodent control and an area available per hen in the chicken run of ≥10sqm were statistically significant risk factors for T. gondii seropositivity. Overall this study showed that exposure to T. gondii is common in small backyard farms but is rare on large organic farms with a high density of free-range hens, even when cats were present on the premises.
Chen, Guangchao; Peijnenburg, Willie J G M; Xiao, Yinlong; Vijver, Martina G (2017-04-05)
A species sensitivity distribution (SSD) for engineered nanomaterials (ENMs) ranks the tested species according to their sensitivity to a certain ENM. An SSD may be used to estimate the maximum acceptable concentrations of ENMs for the purpose of environmental risk assessment. To construct SSDs for metal-based ENMs, more than 1800 laboratory derived toxicity records of metallic ENMs from >300 publications or open access scientific reports were retrieved. SSDs were developed for the metallic ENMs grouped by surface coating, size, shape, exposure duration, light exposure, and different toxicity endpoints. It was found that PVP- and sodium citrate- coatings enhance the toxicity of Ag ENMs as concluded from the relevant SSDs. For the Ag ENMs with different size ranges, differences in behavior and/or effect were only observed at high exposure concentrations. The SSDs of Ag ENMs separated by both shape and exposure duration were all nearly identical. Crustaceans were found to be the most vulnerable group to metallic ENMs. In spite of the uncertainties of the results caused by limited data quality and availability, the present study provided novel information about building SSDs for distinguished ENMs and contributes to the further development of SSDs for metal-based ENMs.
Buesen, Roland; Chorley, Brian N; da Silva Lima, Beatriz; Daston, George; Deferme, Lize; Ebbels, Timothy; Gant, Timothy W; Goetz, Amber; Greally, John; Gribaldo, Laura; et al. (2017-12)
Prevailing knowledge gaps in linking specific molecular changes to apical outcomes and methodological uncertainties in the generation, storage, processing, and interpretation of 'omics data limit the application of 'omics technologies in regulatory toxicology. Against this background, the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) convened a workshop Applying 'omics technologies in chemicals risk assessment that is reported herein. Ahead of the workshop, multi-expert teams drafted frameworks on best practices for (i) a Good-Laboratory Practice-like context for collecting, storing and curating 'omics data; (ii) the processing of 'omics data; and (iii) weight-of-evidence approaches for integrating 'omics data. The workshop participants confirmed the relevance of these Frameworks to facilitate the regulatory applicability and use of 'omics data, and the workshop discussions provided input for their further elaboration. Additionally, the key objective (iv) to establish approaches to connect 'omics perturbations to phenotypic alterations was addressed. Generally, it was considered promising to strive to link gene expression changes and pathway perturbations to the phenotype by mapping them to specific adverse outcome pathways. While further work is necessary before gene expression changes can be used to establish safe levels of substance exposure, the ECETOC workshop provided important incentives towards achieving this goal.
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