Antibody response against Trichinella spiralis in experimentally infected rats is dose dependent

Domestic pigs are the main representatives of the domestic cycle of Trichinella spiralis that play a role in transmission to humans. In Europe, backyard pigs of small household farms are the most important risks for humans to obtain trichinellosis. Rats might play a role in the transmission of Trichinella spiralis from domestic to sylvatic animals and vice versa. In order to be able to investigate the role of wild rats in the epidemiology of T. spiralis in The Netherlands, we studied the dynamics of antibody response after T. spiralis infections in experimental rats, using infection doses ranging from very low (10 muscle larvae, ML, per rat) to very high (16 000 ML per rat). To evaluate the feasibility of rats surviving high infection doses with T. spiralis, clinical and pathological parameters were quantified. Serological tools for detecting T. spiralis in rats were developed to quantitatively study the correlation between parasite load and immunological response. The results show that an infection dose-dependent antibody response was developed in rats after infection with as low as 10 ML up to a level of 10 000 ML. A positive correlation was found between the number of recovered ML and serum antibody levels, although specific measured antibody levels correspond to a wide range of LPG values. Serum antibodies of rats that were infected even with 10 or 25 ML could readily be detected by use of the T. spiralis western blot 2 weeks post infection. We conclude that based on these low infection doses, serologic tests are a useful tool to survey T. spiralis in wild rats

Long-term exposure to environmental concentrations of the pharmaceutical ethynylestradiol causes reproductive failure in fish

International audienceHeightened concern over endocrine-disrupting chemicals is driven by the hypothesis that they could reduce reproductive success and affect wildlife populations, but there is little evidence for this expectation. The pharmaceutical ethynylestradiol (EE(2)) is a potent endocrine modulator and is present in the aquatic environment at biologically active concentrations. To investigate impacts on reproductive success and mechanisms of disruption, we exposed breeding populations (n = 12) of zebrafish (Danio rerio) over multiple generations to environmentally relevant concentrations of EE(2). Life-long exposure to 5 ng/L EE(2) in the F, generation caused a 56% reduction in fecundity and complete population failure with no fertilization. Conversely, the same level of exposure for up to 40 days in mature adults in the parental F(0) generation had no impact on reproductive success. Infertility in the F, generation after life-long exposure to 5 ng/L EE(2) was due to disturbed sexual differentiation, with males having no functional testes and either undifferentiated or intersex gonads. These F, males also showed a reduced vitellogenic response when compared with F(0) males, indicating an acclimation to EE(2) exposure. Deputation studies found only a partial recovery in reproductive capacity after 5 months. Significantly, even though the F(0) males lacked functional testes, they showed male-pattern reproductive behavior, inducing the spawning act and competing with healthy males to disrupt fertilization. Endocrine disruption is therefore likely to affect breeding dynamics and reproductive success in group-spawning fish. Our findings raise major concerns about the population-level impacts for wildlife of long-term exposure to low concentrations of estrogenic endocrine disruptors

The assessment of the safety for the consumer of feed additives and additives added to foods of animal origin

Safe animal feed is important for the health of animals, the safety of the consumer of food of animal origin and for the environment. There is a close link between the safety of animal feed and the foods derived from the animals given this fodder. Additives are purposely added to animal feed or to food of animal origin with the aim to improve the quality of the feed and the quality of the food of animal origin. Assessing the safety of feed additives or additives added to food of animal origin requires a multidisciplinary approach to asses all aspects relevant to the intended use of that compound. The principles of the assessment of the safety of the consumer exposed to compounds via food from animal origin are described. An overview is given of the toxicity studies that are used to assess the safety, including the method to derive the safe intake for the consumer based on the outcome of the toxicity studies. The approach is illustrated by four examples of commercially available additives in order to illustrate how regulatory authorities, i.e. the European Food Safety Authority, evaluate the (absence of) potential health effects for consumers

Effects of the antithyroid agent propylthiouracil in a partial life cycle assay with zebrafish

Some ubiquitous pollutants of the aquatic environment, such as PCBs or other polyhalogenated aromatic hydrocarbons, may disrupt the thyroid hormone system. In a partial life cycle assay with zebrafish (Danio rerio), we studied the effects of the reference compound propylthiouracil (PTU) on reproduction, growth and development, histopathology of some target tissues, and plasma thyroid hormone levels. PTU induced a concentration-dependent increase of egg production with a concomitant decrease of mature oocyte size but had no effect on fertilization rate or hatching.Piet Beekhof, Bhawani Nagarajah, Sisca de Vlugt, Joke Robinson, and Sandra de Waal are acknowledged for their dedicated technical assistance, and Dr. Saskia Sterk (Laboratory for Food and Residue analysis, European Union Community Reference Laboratory, RIVM) is acknowledged for PTUmeasurements. This study was ordered by the European Commission (Project B6-7920/98/00025) and the Dutch Environment Ministry VROM (Project M/640920)

Antibody response against <it>Trichinella spiralis </it>in experimentally infected rats is dose dependent

Abstract Domestic pigs are the main representatives of the domestic cycle of Trichinella spiralis that play a role in transmission to humans. In Europe, backyard pigs of small household farms are the most important risks for humans to obtain trichinellosis. Rats might play a role in the transmission of Trichinella spiralis from domestic to sylvatic animals and vice versa. In order to be able to investigate the role of wild rats in the epidemiology of T. spiralis in The Netherlands, we studied the dynamics of antibody response after T. spiralis infections in experimental rats, using infection doses ranging from very low (10 muscle larvae, ML, per rat) to very high (16 000 ML per rat). To evaluate the feasibility of rats surviving high infection doses with T. spiralis, clinical and pathological parameters were quantified. Serological tools for detecting T. spiralis in rats were developed to quantitatively study the correlation between parasite load and immunological response. The results show that an infection dose-dependent antibody response was developed in rats after infection with as low as 10 ML up to a level of 10 000 ML. A positive correlation was found between the number of recovered ML and serum antibody levels, although specific measured antibody levels correspond to a wide range of LPG values. Serum antibodies of rats that were infected even with 10 or 25 ML could readily be detected by use of the T. spiralis western blot 2 weeks post infection. We conclude that based on these low infection doses, serologic tests are a useful tool to survey T. spiralis in wild rats.</p

Comparative gene expression profiling in two congenic mouse strains following <it>Bordetella pertussis </it>infection

<p>Abstract</p> <p>Background</p> <p>Susceptibility to <it>Bordetella pertussis </it>infection varies widely. These differences can partly be explained by genetic host factors. HcB-28 mice are more resistant to <it>B. pertussis </it>infection than C3H mice, which could partially be ascribed to the <it>B</it>. <it>pertussis susceptibility locus-1 </it>(<it>Bps1</it>) on chromosome 12. The presence of C57BL/10 genome on this locus instead of C3H genome resulted in a decreased number of bacteria in the lung. To further elucidate the role of host genetic factors, in particular in the <it>Bps1 </it>locus, in <it>B. pertussis </it>infection, and to identify candidate genes within in this region, we compared expression profiles in the lungs of the C3H and HcB-28 mouse strains following <it>B. pertussis </it>inoculation. Twelve and a half percent of the genomes of these mice are from a different genetic background.</p> <p>Results</p> <p>Upon <it>B. pertussis </it>inoculation 2,353 genes were differentially expressed in the lungs of both mouse strains. Two hundred and six genes were differentially expressed between the two mouse strains, but, remarkably, none of these were up- or down-regulated upon <it>B. pertussis </it>infection. Of these 206 genes, 17 were located in the <it>Bps1 </it>region. Eight of these genes, which showed a strong difference in gene expression between the two mouse strains, map to the immunoglobulin heavy chain complex (<it>Igh</it>).</p> <p>Conclusion</p> <p>Gene expression changes upon <it>B. pertussis </it>infection are highly identical between the two mouse strains despite the differences in the course of <it>B. pertussis </it>infection. Because the genes that were differentially regulated between the mouse strains only showed differences in expression before infection, it appears likely that such intrinsic differences in gene regulation are involved in determining differences in susceptibility to <it>B. pertussis </it>infection. Alternatively, such genetic differences in susceptibility may be explained by genes that are not differentially regulated between these two mouse strains. Genes in the <it>Igh </it>complex, among which <it>Igh-1a/b</it>, are likely candidates to explain differences in susceptibility to <it>B. pertussis</it>. Thus, by microarray analysis we significantly reduced the number of candidate susceptibility genes within the <it>Bps1 </it>locus. Further work should establish the role of the <it>Igh </it>complex in <it>B. pertussis </it>infection.</p