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In order to assess the risk of SARS-CoV-2 infection, transmission and reservoir development in swine, we combined results of an experimental and two observational studies. First, intranasal and intratracheal challenge of eight pigs did not result in infection, based on clinical signs and PCR on swab and lung tissue samples. Two serum samples returned a low positive result in virus neutralization, in line with findings in other infection experiments in pigs. Next, a retrospective observational study was performed in the Netherlands in the spring of 2020. Serum samples (N =417) obtained at slaughter from 17 farms located in a region with a high human case incidence in the first wave of the pandemic. Samples were tested with protein micro array, plaque reduction neutralization test and receptor-binding-domain ELISA. None of the serum samples was positive in all three assays, although six samples from one farm returned a low positive result in PRNT (titers 40–80). Therefore we conclude that serological evidence for large scale transmission was not observed. Finally, an outbreak of respiratory disease in pigs on one farm, coinciding with recent exposure to SARS-CoV-2 infected animal caretakers, was investigated. Tonsil swabs and paired serum samples were tested. No evidence for infection with SARS-CoV-2 was found. In conclusion, Although in both the experimental and the observational study few samples returned low antibody titer results in PRNT infection with SARS-CoV-2 was not confirmed. It was concluded that sporadic infections in the field cannot be excluded, but large-scale SARS-CoV-2 transmission among pigs is unlikely.

Objective: Unprecedented SARS-CoV-2 infections in farmed minks raised immediate concerns regarding transmission to humans and initiated intensive environmental investigations to assess occupational and environmental exposure. Methods: Air sampling was performed at infected Dutch mink farms, at farm premises and at nearby residential sites. A range of other environmental samples were collected from minks' housing units, including bedding materials. SARS-CoV-2 RNA was analysed in all samples by quantitative PCR. Results: Inside the farms, considerable levels of SARS-CoV-2 RNA were found in airborne dust, especially in personal inhalable dust samples (approximately 1000-10 000 copies/m3). Most of the settling dust samples tested positive for SARS-CoV-2 RNA (82%, 75 of 92). SARS-CoV-2 RNA was not detected in outdoor air samples, except for those collected near the entrance of the most recently infected farm. Many samples of minks' housing units and surfaces contained SARS-CoV-2 RNA. Conclusions: Infected mink farms can be highly contaminated with SARS-CoV-2 RNA. This warns of occupational exposure, which was substantiated by considerable SARS-CoV-2 RNA concentrations in personal air samples. Dispersion of SARS-CoV-2 to outdoor air was found to be limited and SARS-CoV-2 RNA was not detected in air samples collected beyond farm premises, implying a negligible risk of environmental exposure to nearby communities. Our occupational and environmental risk assessment is in line with whole genome sequencing analyses showing mink-to-human transmission among farm workers, but no indications of direct zoonotic transmission events to nearby communities.

Micro algae's are used as alternative protein source in human and animal diets. Besides micro algae contain substantial amounts of proteins they also contain a high concentration of, often unique, biological and chemical substances with potential to induce beneficial and health promoting effects in humans and animals. This study was set up to evaluate the potential of these substances to improve (intestinal) health. The effect of extracts prepared from 3 monocultures of micro algae's (Chlorella vulgaris [C], Haematococcus pluvialis [H], and Spirulina platensis [S]) and a mixed culture of micro algae's (AM; a mixture of Scenedesmus sp. and Chlorella sp. ) was studied in the presence and absence of the enterotoxigenic bacterium Escherichia coli k99 strain (ETEC, [E]) as an in vitro challenge. The E.coli-k99 strain with adhesion factor F41 (41/32) was isolated from a mastitis-infected udder. Gene expression was measured in cultured intestinal porcine epithelium cells (IPECJ2 cell line) after 2 and 6 hours incubation with C, H, and S extracts, and after 6 hours with the AM extract, using “whole genome” porcine microarrays. Gene expression profiles were analysed using functional bioinformatics programs to provide insight in the biological processes induced by micro algae extracts.

Porcine epidemic diarrhoea virus, strain CV777, was initially characterized in 1978 as the causative agent of a disease first identified in the UK in 1971. This coronavirus has been widely distributed among laboratories and has been passaged both within pigs and in cell culture. To determine the variability between different stocks of the PEDV strain CV777, sequencing of the full-length genome (ca. 28kb) has been performed in 6 different laboratories, using different protocols. Not surprisingly, each of the different full genome sequences were distinct from each other and from the reference sequence (Accession number AF353511) but they are >99% identical. Unique and shared differences between sequences were identified. The coding region for the surface-exposed spike protein showed the highest proportion of variability including both point mutations and small deletions. The predicted expression of the ORF3 gene product was more dramatically affected in three different variants of this virus through either loss of the initiation codon or gain of a premature termination codon. The genome of one isolate had a substantially rearranged 5´-terminal sequence. This rearrangement was validated through the analysis of sub-genomic mRNAs from infected cells. It is clearly important to know the features of the specific sample of CV777 being used for experimental studies.

This study investigated the effect of four different nutritional interventions, applied during the first week of life, on immune competence parameters of broiler chickens. The four (dietary) interventions were antibiotics in the drinking water, 25% inclusion of rye in the feed, beta-glucans from Saccharomyces cerevisiae, and coated butyrate. Broiler chickens (between 1 and 2 weeks of age) were subjected to a Necrotic Enteritis (NE) challenge. A positive and negative control treatment (challenged vs. non-challenged chickens, respectively) was included to estimate the effect of the NE challenge. It was hypothesized that applying a nutritional intervention in the first week of life would affect the microbiota colonization, immune system programming, and consequently the quantitative disease phenotype (lesions scores as a result of the NE challenge). The NE challenge did affect the overall performance during the first 2 weeks post-challenge. The antibiotics group showed significant effects on different biological levels: (temporary) increased performance, deviating microbiota composition, increased gene expression in barrier function processes, whereas decreased gene expression in immune related processes, and a higher villi to crypt ratio compared to the (un)challenged control treatment. In the other treatments only significant differences in bacterial genera were observed. In conclusion, this study has shown that it is probable to disturb the gut system development, whereby giving antibiotics (amoxicillin) gives an effect on multiple biological levels. In addition, the other dietary perturbations, i.e. change in feed composition (25% inclusion of rye), feed additives (beta-glucans or coated butyrate) only affected the microbiota composition to some extent.

Het doel van dit project is om een “meetlat” te ontwikkelen die de effecten van (voedings)interventies gericht op de verbetering van de immuuncompetentie van varkens, pluimvee en vleeskalveren kan vaststellen. Immuuncompetentie is binnen dit project gedefinieerd als het vermogen van dieren om effectieve responsen van het immuunsysteem te tonen op het moment dat de gezondheid van het dier onder druk wordt gezet. Een meetlat voor immuuncompetentie kan in de toekomst door de diervoedingssector gebruikt worden bij de ontwikkeling en evaluatie van nieuwe voerconcepten, ingrediënten en additieven gericht op de verbetering en ondersteuning van diergezondheid. Het is bekend dat de samenstelling van de voeding van jonge dieren invloed heeft op de functionele ontwikkeling van het maagdarmkanaal en op de samenstelling van de daarin aanwezige microbiota. De interacties tussen de microbiota en de weefsels van het darmkanaal (cross talk) hebben een belangrijke invloed op de ontwikkeling van immuuncompetentie. Daarom wordt in dit project gefocust op de effecten van (voedings)interventies op de microbiota, genexpressie veranderingen in darmweefsel, en morfologische en immunologische veranderen in de darm. De hier gepresenteerde meetlat voor immuuncompetentie is gebaseerd op de resultaten van onderzoek binnen het VDI programma van Feed4Foodure (projecten VDI-11; vleeskuikens, VDI-12; biggen, VDI- 13; gespeende biggen en kalveren) waarin m.b.v. model interventies de effecten van variatie in voersamenstelling op de microbiota samenstelling in het darmkanaal, de biologische responsen van darmweefsel en de zoötechnische dierprestaties zijn onderzocht. In de hier gepresenteerde meetlat worden gemeten effecten in deze studies aan elkaar gerelateerd en functioneel inzichtelijk gemaakt. Dit rapport beschrijft de ontwikkeling en totstandkoming van een eerste versie van de meetlat. Hierbij worden gemaakte keuzes, beperkingen en mogelijkheden van de meetlat bediscussieerd. Tenslotte wordt in

BackgroundGene expression profiles of intestinal mucosa of chickens and pigs fed over long-term periods (days/weeks) with a diet rich in rye and a diet supplemented with zinc, respectively, or of chickens after a one-day amoxicillin treatment of chickens, were recorded recently. Such dietary interventions are frequently used to modulate animal performance or therapeutically for monogastric livestock. In this study, changes in gene expression induced by these three interventions in cultured “Intestinal Porcine Epithelial Cells” (IPEC-J2) recorded after a short-term period of 2 and 6 hours, were compared to the in vivo gene expression profiles in order to evaluate the capability of this in vitro bioassay in predicting in vivo responses.MethodsLists of response genes were analysed with bioinformatics programs to identify common biological pathways induced in vivo as well as in vitro. Furthermore, overlapping genes and pathways were evaluated for possible involvement in the biological processes induced in vivo by datamining and consulting literature.ResultsFor all three interventions, only a limited number of identical genes and a few common biological processes/pathways were found to be affected by the respective interventions. However, several enterocyte-specific regulatory and secreted effector proteins that responded in vitro could be related to processes regulated in vivo, i.e. processes related to mineral absorption, (epithelial) cell adherence and tight junction formation for zinc, microtubule and cytoskeleton integrity for amoxicillin, and cell-cycle progression and mucus production for rye.ConclusionsShort-term gene expression responses to dietary interventions as measured in the in vitro bioassay have a low predictability for long-term responses as measured in the intestinal mucosa in vivo. The short-term responses of a set regulatory and effector genes, as measured in this bioassay, however, provided additional insight into how specific processes in piglets a