Crossover animal trials were performed with intravenous and oral administration of deoxynivalenol-3-β-D-glucoside (DON3G) and deoxynivalenol (DON) to broiler chickens and pigs. Systemic plasma concentrations of DON, DON3G and de-epoxy-DON were quantified using liquid chromatography-tandem mass spectrometry. Liquid chromatography coupled to high-resolution mass spectrometry was used to unravel phase II metabolism of DON. Additionally for pigs, portal plasma was analysed to study presystemic hydrolysis and metabolism. Data were processed via tailor-made compartmental toxicokinetic models. The results in broiler chickens indicate that DON3G is not hydrolysed to DON in vivo. Furthermore, the absolute oral bioavailability of DON3G in broiler chickens was low (3.79 ± 2.68 %) and comparable to that of DON (5.56 ± 2.05 %). After PO DON3G administration to pigs, only DON was detected in plasma, indicating a complete presystemic hydrolysis of the absorbed fraction of DON3G. However, the absorbed fraction of DON3G, recovered as DON, was approximately 5 times lower than after PO DON administration, 16.1 ± 5.4 compared with 81.3 ± 17.4 %. Analysis of phase II metabolites revealed that biotransformation of DON and DON3G in pigs mainly consists of glucuronidation, whereas in chickens predominantly conjugation with sulphate occurred. The extent of phase II metabolism is notably higher for chickens than for pigs, which might explain the differences in sensitivity of these species to DON. Although in vitro studies demonstrate a decreased toxicity of DON3G compared with DON, the species-dependent toxicokinetic data and in vivo hydrolysis to DON illustrate the toxicological relevance and consequently the need for further research to establish a tolerable daily intake.

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Enterotoxigenic Escherichia coli (ETEC) strains that produce heat-stable (ST) and/or heat - labile (LT) enterotoxins are cause of post – weaning diarrhea in piglets. However, the relative importance of the different enterotoxins in host immune responses against ETEC infection has been poorly defined. In the present study, several isogenic mutant strains of an O149:F4ac + , LT + STa + STb + ETEC strain were constructed that lack the expression of LT in combination with one or both types of ST enterotoxins (STa and/or STb). The small intestinal segment perfusion (SISP) technique and microarray analysis were used to study host early immune responses induced by these mutant strains 4 h after infection in comparison to the wild type strain and a PBS control. Simultaneously, net fluid absorption of pig small intestinal mucosa was measured 4 h after infection, allowing us to correlate enterotoxin secretion with gene regulation. Microarray analysis showed on the one hand a non-toxin related general antibacterial response comprising genes such as PAP, MMP1 and IL8 . On the other hand, results suggest a dominant role for STb in small intestinal secretion early after post-weaning infection, as well as in the induced innate immune response through differential regulation of immune mediators like interleukin 1 and interleukin 17.

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Bovine necrohemorrhagic enteritis is a major cause of mortality in veal calves. Clostridium perfringens is considered as the causative agent, but there has been controversy on the toxins responsible for the disease. Recently, it has been demonstrated that a variety of C. perfringens type A strains can induce necrohemorrhagic lesions in a calf intestinal loop assay. These results put forward alpha toxin and perfringolysin as potential causative toxins, since both are produced by all C. perfringens type A strains. The importance of perfringolysin in the pathogenesis of bovine necrohemorrhagic enteritis has not been studied before. Therefore, the objective of the current study was to evaluate the role of perfringolysin in the development of necrohemorrhagic enteritis lesions in calves and its synergism with alpha toxin. A perfringolysin-deficient mutant, an alpha toxin-deficient mutant and a perfringolysin alpha toxin double mutant were less able to induce necrosis in a calf intestinal loop assay as compared to the wild-type strain. Only complementation with both toxins could restore the activity to that of the wild-type. In addition, perfringolysin and alpha toxin had a synergistic cytotoxic effect on bovine endothelial cells. This endothelial cell damage potentially explains why capillary hemorrhages are an initial step in the development of bovine necrohemorrhagic enteritis. Taken together, our results show that perfringolysin acts synergistically with alpha toxin in the development of necrohemorrhagic enteritis in a calf intestinal loop model and we hypothesize that both toxins act by targeting the endothelial cells.