Drinking water application of Denagard® Tiamulin for control of Brachyspira pilosicoli infection of laying poultry.

Avian intestinal spirochaetosis (AIS) caused by Brachyspira spp., and notably Brachyspira pilosicoli, is common in layer flocks and reportedly of increasing incidence in broilers and broiler breeders. Disease manifests as diarrhoea, increased feed consumption, reduced growth rates and occasional mortality in broilers and these signs are shown in layers also associated with a delayed onset of lay, reduced egg weights, faecal staining of eggshells and non-productive ovaries. Treatment with Denagard® Tiamulin has been used to protect against B. pilosicoli colonisation, persistence and clinical presentation of AIS in commercial layers, but to date there has been no definitive study validating efficacy. Here, we used a poultry model of B. pilosicoli infection of layers to compare the impact of three doses of Denagard® Tiamulin. Four groups of thirty 17 week old commercial pre-lay birds were all challenged with B. pilosicoli strain B2904 with three oral doses two days apart. All birds were colonised within 2 days after the final oral challenge and mild onset of clinical signs were observed thereafter. A fifth group that was unchallenged and untreated was also included for comparison as healthy birds. Five days after the final oral Brachypira challenge three groups were given Denagard® Tiamulin in drinking water made up following the manufacturer's recommendations with doses verified as 58.7 ppm, 113 ppm and 225 ppm. Weight gain body condition and the level of diarrhoea of birds infected with B. pilosicoli were improved and shedding of the organism reduced significantly (p=0.001) following treatment with Denagard® Tiamulin irrespective of dose given. The level and duration of colonisation of organs of birds infected with B. pilosicoli was also reduced. Confirming previous findings we showed that the ileum, caeca, colon, and both liver and spleen were colonised and here we demonstrated that treatment with Denagard® Tiamulin resulted in significant reduction in the numbers of Brachyspira found in each of these sites and dramatic reduction in faecal shedding (p<0.001) to approaching zero as assessed by culture of cloacal swabs. Although the number of eggs produced per bird and the level of eggshell staining appeared unaffected, egg weights of treated birds were greater than those of untreated birds for a period of approximately two weeks following treatment. These data conclusively demonstrate the effectiveness of Denagard® Tiamulin in reducing B. pilosicoli infection in laying hens.

Toll-dependent antimicrobial responses in Drosophila larval fat body require Spätzle secreted by haemocytes.

In Drosophila, the humoral response characterised by the synthesis of antimicrobial peptides (AMPs) in the fat body (the equivalent of the mammalian liver) and the cellular response mediated by haemocytes (blood cells) engaged in phagocytosis represent two major reactions that counter pathogens. Although considerable analysis has permitted the elucidation of mechanisms pertaining to the two responses individually, the mechanism of their coordination has been unclear. To characterise the signals with which infection might be communicated between blood cells and fat body, we ablated circulating haemocytes and defined the parameters of AMP gene activation in larvae. We found that targeted ablation of blood cells influenced the levels of AMP gene expression in the fat body following both septic injury and oral infection. Expression of the AMP gene drosomycin (a Toll target) was blocked when expression of the Toll ligand Spätzle was knocked down in haemocytes. These results show that in larvae, integration of the two responses in a systemic reaction depend on the production of a cytokine (spz), a process that strongly parallels the mammalian immune response.

Assessment of the potential allergenicity of a Milk Basic Protein fraction.

BACKGROUND: A specific basic fraction of bovine milk, termed Milk Basic Protein (MBP), has the potential to provide nutritionally important benefits if used as a food ingredient. Although derived from milk, MBP is intended for use as an ingredient in other foods. Cows' milk is a well studied, commonly allergenic food. Although the proteins in MBP are not identified as milk allergens, food products containing MBP will be labelled as containing milk as a caution to milk allergic consumers under food labelling guidelines in the US and the European Union as MBP has not been demonstrated to be free of milk allergens. However, as part of an overall safety evaluation of MBP, the developers sought to evaluate the potential allergenicity of the primary protein components for characteristics of allergenic food proteins and to assess whether intake of these proteins at intended use levels could present a significant new allergenic risk for consumers. OBJECTIVE: To evaluate the potential allergenicity of the five identified proteins in MBP. While extensive studies have not demonstrated allergenicity of lactoferrin, the four other proteins are less studied. The four were tested here by sequence identity comparison to known allergens, and for stability of these proteins in acidic pepsin as a characteristic common to many food allergens. METHODS: Sequences of the proteins were compared to those listed in AllergenOnline.com, by methods recommended for the evaluation of proteins introduced in crops through genetic engineering. Pepsin stability was assessed by incubating the various proteins in simulated gastric fluid at pH 1.2 with porcine pepsin for up to 60 min at 37 degrees C, with samples withdrawn and analyzed at specific times. RESULTS: No significant sequence similarities were identified for the MBP proteins compared to known allergens. All but one of the protein components of MBP were digested relatively quickly by pepsin. The more stable protein will be of low abundance as consumed in contrast to most pepsin-stable food allergens. CONCLUSIONS: Based on molecular characteristics and expected exposure, the protein components in MBP are unlikely to present any increased risk of allergy for milk allergic subjects or of cross-reactivity for other allergic subjects. However, since the proteins are derived from milk, products containing MBP will need to be labelled as containing milk proteins to warn milk allergic subjects of the potential risk of allergic reactions.