Induction of a local anti-IpaC antibody response in mice by use of a Shigella flexneri 2a vaccine candidate: implications for use of IpaC as a protein carrier

The capacity of Shigella flexneri to act as a delivery system for stimulation of local immunity was investigated by use of an S. Flexneri 2a vaccine candidate (SC602). This vaccine strain was constructed by deletion of virulence genes responsible for dissemination (icsA) and survival (iuc:iut) of bacteria within the colonic mucosa. Among the most immunogenic S. flexneri 2a proteins inducing a local immunoglobulin A antibody response, the IpaC invasion was selected as a potential protein carrier. Overexpression of IpaC from a plasmid in trans within SC602 (SC602/pIpaC) was shown to be required for the induction of optimal anti-IpaC antibody response in the murine pulmonary infection model. A weak anti-IpaC antibody response was obtained after intranasal inoculations with SC602/pIpaC live bacteria. This response was enhanced by combining systemic priming with SC602/pIpaC killed bacteria and local boosting with SC602/pIpaC live bacteria. These results suggest that naive B cells primed systemically could account for local antibody production. This immunization protocol will allow further evaluation of the immunogenicity of IpaC hybrid proteins expresses in SC602.     

Bio-ethanol production by fermentation of ricotta cheese whey as an effective alternative non-vegetable source

The aim of the present paper is to investigate the feasibility of bio-ethanol production by batch fermentation of ricotta cheese whey (“Scotta”), a dairy industry waste characterized by lactose concentration ranging from 4.5% to 5.0% (w/w) and, with respect to traditional (raw) whey, by much lower protein content. Scotta, therefore, could represent an effective non-vegetable source for renewable energy production. The microrganism used to carry out the fermentation processes was the yeast Kluyveromyces marxianus. Preliminary experiments, performed in aerobic conditions on different volumes of scotta, have shown the actual growth of the yeast. The subsequent fermentation experiments were carried out, in anaerobic conditions, on three different substrates: scotta, raw cheese whey and deproteinized whey. The experimental data have demonstrated the process feasibility: scotta is an excellent substrate for fermentation and exhibits better performance with respect to both raw cheese whey and deproteinized whey. Complete lactose consumption, indeed, was observed in the shortest time (13 h) and with the highest ethanol yield (97% of the theoretical value).     

Design and realization of multiple quarter-wave phase-shiftsUV-written bandpass filters in optical fibers

Ultraviolet (UV)-written optical fiber bandpass filters based on multiple quarter-wave phase-shifts, up to eight, are presented and modeled. It is demonstrated that the shape of the bandpass peak can be tailored by optimization of the phase-shifts locations. We show that flat top bandpass peak with negligible ripples (<0.01 dB) at the top can be designed and that a tradeoff between nearly rectangular shape and stopband width occurs when gratings containing more than two phase-shifts are to be used. We also present experimental spectral responses of gratings with up to three phase-shifts and comparisons with theoretical results     

Identification and cellular localization of the actin-binding protein ABP-120 from Entamoeba histolytica

Several actin-binding proteins participate in the morphological changes that occur during amoeboid movement. The gene encoding one of these proteins, the gelation factor ABP-120, was identified and characterized from trophozoites of Entamoeba histolytica. The sequence contains 2574 nucleotides, with an open reading frame of 858 amino acids, giving a protein of 93 kDa belonging to the spectrin family. The N-terminal domain of ABP-120 from E. histolytica revealed a consensus site for actin binding homologous to the actin-binding sites of ABP-120 of Dictyostelium discoideum, alpha-actinin and spectrin. Analysis of the central domain revealed the presence of four repeats of a 73-amino-acid motif constituting 31% of the protein. In addition, a stretch of 105 amino acids was highly divergent when compared with the C-terminal domain of D. discoideum ABP-120. This sequence showed short motifs that are homologous to microtubule-binding domains. We found that ABP-120 from E. histolytica binds to F-actin. In addition, upon motility of the parasite, this protein localized in the pseudopod and the uroid region, implying a role for ABP-120 in movement and capping of surface receptors in E. histolytica.     

Alteration of HLA-B27 peptide presentation after infection of transfected murine L cells by Shigella flexneri

Shigella flexneri is a triggering agent for reactive arthritis in HLA-B27-susceptible individuals. Considering the intracellular multiplication of bacteria, it seems likely that bacterial peptides may be presented by the major histocompatibility complex (MHC) class I pathway. To examine this hypothesis, we infected HLA-B*2705- and/or human beta2-microglobulin-transfected murine L-cell lines with M90T, an invasive strain of S. flexneri. Bacterial infection induced no detectable modifications in the biosynthesis and expression level of HLA-B27, as assessed by immunoprecipitation, Northern blot analysis, and flow cytometry. Using confocal microscopy, we observed that bacterial infection induced a clustering of HLA-B27 molecules during macropinocytosis and before bacterial dissemination from cell to cell. Peptides naturally bound to HLA-B27 molecules were acid eluted from infected cells and separated by high-performance liquid chromatography. Major differences were observed in high-performance liquid chromatography profiles and in the nature of peptides presented following bacterial infection. Although most of the antigens presented were not accessed by Edman degradation, we obtained two sequences partially homologous to bacterial proteins. These peptides lacked the major HLA-B27 peptide anchor (Arg) at position 2, and one had an unusual length of 14 amino acids. These data suggest that alterations in the peptide presentation by HLA-B27 occur during infection, which could be relevant to the pathogenesis of HLA-B27-related arthritis.     

Interferon alpha inhibits a Src-mediated pathway necessary for Shigella-induced cytoskeletal rearrangements in epithelial cells

Shigella flexneri, the causative agent of bacillary dysentery, has the ability to enter nonphagocytic cells. The interferon (IFN) family of cytokines was found to inhibit Shigella invasion of cultured epithelial cells. We show here that IFN-alpha inhibits a Src-dependent signaling cascade triggered by Shigella that leads to the reorganization of the host cell cytoskeleton. Immunofluorescence studies showed that IFN-alpha inhibits Shigella-induced actin polymerization required for bacterial entry into cells. Phosphorylation of cortactin, a Src-substrate specifically tyrosyl-phosphorylated during Shigella entry, was inhibited by IFN-alpha. Overexpression of a dominant interfering form of pp60c-src led to inhibition of Shigella-induced cytoskeletal rearrangements and decreased cortactin phosphorylation indicating a role for Src in Shigella entry. Also, Shigella uptake in cells that expressed constitutively active Src was unaffected by IFN-alpha treatment. We conclude that Src kinase activity is necessary for Shigella invasion of epithelial cells and that IFN-alpha inhibits this Src-dependent signaling pathway.     

Enhancing cultural recommendations through social and linked open data

In this article, we describe a hybrid recommender system (RS) in the artistic and cultural heritage area, which takes into account the activities on social media performed by the target user and her friends, and takes advantage of linked open data (LOD) sources. Concretely, the proposed RS (1) extracts information from Facebook by analyzing content generated by users and their friends; (2) performs disambiguation tasks through LOD tools; (3) profiles the active user as a social graph; (4) provides her with personalized suggestions of artistic and cultural resources in the surroundings of the user’s current location. The last point is performed by integrating collaborative filtering algorithms with semantic technologies in order to leverage LOD sources such as DBpedia and Europeana. Based on the recommended points of cultural interest, the proposed system is also able to suggest to the active user itineraries among them, which meet her preferences and needs and are sensitive to her physical and social contexts as well. Experimental results on real users showed the effectiveness of the different modules of the proposed recommender.