Cytokine responses in birds challenged with the human food-borne pathogen Campylobacter jejuni implies a Th17 response

Development of process orientated understanding of cytokine interactions within the gastrointestinal tract during an immune response to pathogens requires experimentation and statistical modelling. The immune response against pathogen challenge depends on the specific threat to the host. Here, we show that broiler chickens mount a breed-dependent immune response to Campylobacter jejuni infection in the caeca by analysing experimental data using frequentist and Bayesian structural equation models (SEM). SEM provides a framework by which cytokine interdependencies, based on prior knowledge, can be tested. In both breeds important cytokines including pro-inflammatory interleukin (IL)-1β, , IL-4, IL-17A, interferon (IFN)-γ and anti-inflammatory IL-10 and transforming growth factor (TGF)-β4 were expressed post-challenge. The SEM revealed a putative regulatory pathway illustrating a T helper (Th)17 response and regulation of IL-10, which is breed-dependent. The prominence of the Th17 pathway indicates the cytokine response aims to limit the invasion or colonization of an extracellular bacterial pathogen but the time-dependent nature of the response differs between breeds

Adding function to the genome of African Salmonella Typhimurium ST313 strain D23580.

Salmonella Typhimurium sequence type (ST) 313 causes invasive nontyphoidal Salmonella (iNTS) disease in sub-Saharan Africa, targeting susceptible HIV+, malarial, or malnourished individuals. An in-depth genomic comparison between the ST313 isolate D23580 and the well-characterized ST19 isolate 4/74 that causes gastroenteritis across the globe revealed extensive synteny. To understand how the 856 nucleotide variations generated phenotypic differences, we devised a large-scale experimental approach that involved the global gene expression analysis of strains D23580 and 4/74 grown in 16 infection-relevant growth conditions. Comparison of transcriptional patterns identified virulence and metabolic genes that were differentially expressed between D23580 versus 4/74, many of which were validated by proteomics. We also uncovered the S. Typhimurium D23580 and 4/74 genes that showed expression differences during infection of murine macrophages. Our comparative transcriptomic data are presented in a new enhanced version of the Salmonella expression compendium, SalComD23580: http://bioinf.gen.tcd.ie/cgi-bin/salcom_v2.pl. We discovered that the ablation of melibiose utilization was caused by three independent SNP mutations in D23580 that are shared across ST313 lineage 2, suggesting that the ability to catabolize this carbon source has been negatively selected during ST313 evolution. The data revealed a novel, to our knowledge, plasmid maintenance system involving a plasmid-encoded CysS cysteinyl-tRNA synthetase, highlighting the power of large-scale comparative multicondition analyses to pinpoint key phenotypic differences between bacterial pathovariants

Genome-wide fitness analyses of the foodborne pathogen Campylobacter jejuni in in vitro and in vivo models.

Campylobacter is the most common cause of foodborne bacterial illness worldwide. Faecal contamination of meat, especially chicken, during processing represents a key route of transmission to humans. There is a lack of insight into the mechanisms driving C. jejuni growth and survival within hosts and the environment. Here, we report a detailed analysis of C. jejuni fitness across models reflecting stages in its life cycle. Transposon (Tn) gene-inactivation libraries were generated in three C. jejuni strains and the impact on fitness during chicken colonisation, survival in houseflies and under nutrient-rich and -poor conditions at 4 °C and infection of human gut epithelial cells was assessed by Tn-insertion site sequencing (Tn-seq). A total of 331 homologous gene clusters were essential for fitness during in vitro growth in three C. jejuni strains, revealing that a large part of its genome is dedicated to growth. We report novel C. jejuni factors essential throughout its life cycle. Importantly, we identified genes that fulfil important roles across multiple conditions. Our comprehensive screens showed which flagella elements are essential for growth and which are vital to the interaction with host organisms. Future efforts should focus on how to exploit this knowledge to effectively control infections caused by C. jejuni.This work was funded by Biotechnology and Biological Sciences Research Council (http://www.bbsrc.ac.uk) grant BB/K004514/1. D.P.W. was funded by a Wellcome Trust (https://wellcome.ac.uk) Infection and Immunity PhD rotation studentship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Distinct Salmonella Enteritidis lineages associated with enterocolitis in high-income settings and invasive disease in low-income settings.

An epidemiological paradox surrounds Salmonella enterica serovar Enteritidis. In high-income settings, it has been responsible for an epidemic of poultry-associated, self-limiting enterocolitis, whereas in sub-Saharan Africa it is a major cause of invasive nontyphoidal Salmonella disease, associated with high case fatality. By whole-genome sequence analysis of 675 isolates of S. Enteritidis from 45 countries, we show the existence of a global epidemic clade and two new clades of S. Enteritidis that are geographically restricted to distinct regions of Africa. The African isolates display genomic degradation, a novel prophage repertoire, and an expanded multidrug resistance plasmid. S. Enteritidis is a further example of a Salmonella serotype that displays niche plasticity, with distinct clades that enable it to become a prominent cause of gastroenteritis in association with the industrial production of eggs and of multidrug-resistant, bloodstream-invasive infection in Africa.This work was supported by the Wellcome Trust. We would like to thank the members of the Pathogen Informatics Team and the core sequencing teams at the Wellcome Trust Sanger Institute (Cambridge, UK). We are grateful to D. Harris for work in managing the sequence data

Magnetic Particle-Scanning for Ultrasensitive Immunodetection On-Chip

We describe the concept of magnetic particle-scanning for on-chip detection of biomolecules: a magnetic particle, carrying a low number of antigens (Ag's) (down to a single molecule), is transported by hydrodynamic forces and is subjected to successive stochastic reorientations in an engineered magnetic energy landscape. The latter consists of a pattern of substrate-bound small magnetic particles that are functionalized with antibodies (Ab's). Subsequationuent counting of the captured Ag-carrying particles provides the detection signal. The magnetic particle-scanning principle is investigated in a custom-built magneto-microfluidic chip and theoretically described by a random walk-based model, in which the trajectory of the contact point between an Ag-carrying particle and the small magnetic particle pattern is described by stochastic moves over the surface of the mobile particle, until this point coincides with the position of an Ag, resulting in the binding of the particle. This model explains the particular behavior of previously reported experimental dose-response curves obtained for two different ligand-receptor systems (biotin/streptavidin and TNF-alpha) over a wide range of concentrations. Our model shows that magnetic particle-scanning results in a very high probability of irrununocomplex formation for very low Ag concentrations, leading to an extremely low limit of detection, down to the single molecule-per-particle level. When compared to other types of magnetic particle-based surface coverage assays, our strategy was found to offer a wider dynamic range (>8 orders of magnitude), as the system does not saturate for concentrations as high as 10(11) Ag molecules in a 5 mu L drop. Furthermore, by emphasizing the importance of maximizing the encounter probability between the Ag and the Ab to improve sensitivity, our model also contributes to explaining the behavior of other particle-based heterogeneous immunoassays

Effect of Cu on InSe/Si(111) heterojunctions

The effect of sequential deposition of Cu onto a 300 Å-thick film of layered InSe epitaxially grown onto a Si(111) substrate, has been studied by Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and photoemission yield spectroscopy (PYS). Cu coverages were from a few hundredth of a monolayer (in terms of InSe atomic surface plane: 1 ML = 7.2 × 1014 at/cm2, that is 0.85 Å of Cu-metal) to 300 ML. The effect of annealings up to 370 °C was also studied. It is shown that Cu has first a non uniform bulk interaction with InSe which looks like an insertion which saturates at 1 ML of Cu per In2Se2 single layer. Then it forms islands which fully mask the surface beyond about 150 ML coverage (130 Å of Cu-metal). Upon annealings beyond 300 °C, the Si substrate behaves as a Cu sink

Analyse par activation neutronique d'amphores gallo-romaines - Mise en évidence d'exportations aux frontières de l'empire

A bunch of 24 amphorae found in Switzerland and Germany, with types encountered in South-Gaul workshops, has been analyzed with neutron activation. Comparison with the reference groups of the 13 workshops characterized for the moment allowed us to classify 70 % of the sampling, either in a workshop precisely, or in an area more or less extended. Cluster analysis is used as a first approach, and a detailed control in then operated taking in account elements mobility and surface of geological outcrops.Un lot de 24 amphores trouvées en Suisse et en Allemagne, de types connus dans les ateliers de la Gaule du Sud a été analysé par activation neutronique. La comparaison avec les groupes de références des 13 ateliers actuellement caractérisés a permis de classer 70 % du lot, soit dans un atelier, soit dans une zone plus ou moins étendue. L'analyse de grappe est utilisée comme première approche et un contrôle détaillé est opéré ensuite, tenant compte de la mobilité des éléments et de l'étendue des affleurements géologiques.Laubenheimer Fanette, Fontes P., Leblanc J., Dodinet M., Lacharme Y., Lleres J., Widemann F. Analyse par activation neutronique d'amphores gallo-romaines - Mise en évidence d'exportations aux frontières de l'empire. In: Revue d'Archéométrie, n°1, 1981. Actes du XXe symposium international d'archéométrie Paris 26-29 mars 1980 Volume III. pp. 155-175