NCT01829932.

A transmissible agent (Breda agent) was isolated from a calf with diarrhea and shown to be infectious by inoculation orally into gnotobiotic and conventionally reared calves. The "Breda" agent had the morphology of a virus and possessed a hemagglutinin. Antigenic studies showed the virus to be antigenically different from bovine coronavirus, parainfluenza 3 virus, bovine rotavirus, bovine parvovirus and bovine pestivirus (BVD). Attempts to culture the virus in cell or organ cultures or in embryonated eggs, were unsuccessful. The virus was either spherical or kidney shaped, with 7-9 nm peplomers on the surface. A few particles possessed coronavirus processes of 17-20 nm, but these were arranged irregularly and were thought to be tissue debris. Three out of eight experimental calves developed severe diarrhea and the lesions in the small and large intestines were similar to those reported for coronavirus. The virus replicated in the jejunal and ileal regions of the small intestine and in the spiral colon, as judged by immunofluorescence. The virus multiplied in all experimental calves and was excreted in the feces; excretion correlating with the onset of diarrhea or a change in the appearance of the feces. There was little or no malabsorption measured by the uptake of D-xylose and the fact that infection of both the crypt and villus epithelial cells was observed, suggests that the pathogenesis may be different from rotavirus and coronavirus. Fourteen of forty seven calves in the outbreak were infected with the virus, virus was not identified in other farm outbreaks of the disease.

Up to 20% of the global population develops gastrointestinal symptoms following a meal 1 , leading to decreased quality of life, significant morbidity and high medical costs. Although the interest of both the scientific and lay community has increased dramatically with the worldwide introduction of gluten-free and other diets, the underlying mechanisms leading to food-induced abdominal complaints remain largely unknown. Here we show that a bacterial infection and bacterial toxins can trigger an immune response leading to the production of dietary antigen-specific IgE antibodies in mice, a mechanism confined to the intestine. Subsequent oral ingestion of the respective dietary antigen results in increased visceral pain via an IgE-and mast cell-dependent mechanism. This aberrant pain signaling results from histamine receptor H1 (H1R)-mediated sensitization of visceral afferents. Moreover, in patients with irritable bowel syndrome (IBS), we show that injection of food antigens (gluten, wheat, soy and milk) into the rectosigmoid induces local edema and mast cell activation. Hence, we have unveiled and characterized a novel peripheral mechanism underlying food-induced abdominal pain, which creates new opportunities for the treatment of IBS and related abdominal pain disorders. MAIN TEXT:The mucosal immune system provides a balanced response to pathogens and harmless commensal bacteria or food antigens, thereby limiting unnecessary inflammation and concomitant tissue damage 2 . This is achieved by an active suppression of cellular and humoral responses to orally administered antigens, a mechanism referred to as oral tolerance 3 . Viral and bacterial infections can, however, interfere with tolerance to dietary antigens, thereby perturbing intestinal homeostasis 4 . An infectious gastroenteritis is a significant risk factor to develop IBS, defined as a constellation of abdominal pain and altered bowel patterns. Between 3 and 36% of enteric infections lead to new onset IBS 5 , while up to 17% of IBS patients report that their symptoms started Supplementary information included as a separate pdf file and videos (Supplementary Information Video 1-4). EXTENDED DATA LEGENDS: Extended Data Fig. 1. Extended analysis of the OVA-specific immune response and VHS in postinfectious mice. a, b, diarrhea development quantification by (a) water content in feces and (b) whole-gut transit time upon gavage of carmine red dye in OVA/sham + OVA, OVA/infected + OVA (n = 10/group) mice. c, quantification of OVA-specific IgE in intestinal homogenates of OVA/sham + OVA, saline/infected + OVA,

Mast cells that are in close proximity to autonomic and enteric nerves release several mediators that cause neuronal hyperexcitability. This study examined whether mast cell tryptase evokes acute and long-term hyperexcitability in submucosal neurons from the guinea-pig ileum by activating proteinase-activated receptor 2 (PAR2) on these neurons. We detected the expression of PAR2 in the submucosal plexus using RT-PCR. Most submucosal neurons displayed PAR2 immunoreactivity, including those colocalizing VIP. Brief (minutes) application of selective PAR2 agonists, including trypsin, the activating peptide SL-NH 2 and mast cell tryptase, evoked depolarizations of the submucosal neurons, as measured with intracellular recording techniques. The membrane potential returned to resting values following washout of agonists, but most neurons were hyperexcitable for the duration of recordings (> 30 min-hours) and exhibited an increased input resistance and amplitude of fast EPSPs. Trypsin, in the presence of soybean trypsin inhibitor, and the reverse sequence of the activating peptide (LR-NH 2 ) had no effect on neuronal membrane potential or long-term excitability. Degranulation of mast cells in the presence of antagonists of established excitatory mast cell mediators (histamine, 5-HT, prostaglandins) also caused depolarization, and following washout of antigen, long-term excitation was observed. Mast cell degranulation resulted in the release of proteases, which desensitized neurons to other agonists of PAR2. Our results suggest that proteases from degranulated mast cells cleave PAR2 on submucosal neurons to cause acute and long-term hyperexcitability. This signalling pathway between immune cells and neurons is a previously unrecognized mechanism that could contribute to chronic alterations in visceral function.