Bacteria cause disease by two general mechanisms: the action of their toxins on host cells and induction of a pro-inflammatory response that can lead to a deleterious cytokine/chemokine response ...(e.g., the so-called cytokine storm) often seen in bacteremia/septicemia. These major mechanisms may overlap due to the action of surface structures that can have direct and indirect actions on phagocytic or non-phagocytic cells. In this respect, the lipid A (endotoxin) component of lipopolysaccharide (LPS) possessed by Gram-negative bacteria has been the subject of literally thousands of studies over the past century that clearly identified it as a key virulence factor in endotoxic shock. In addition to its capacity to modulate inflammatory responses, endotoxin can also modulate bacterial susceptibility to host antimicrobials, such as the host defense peptides termed cationic antimicrobial peptides. This review concentrates on the phosphoethanolamine (PEA) decoration of lipid A in the pathogenic species of the genus
and
. PEA decoration of lipid A is mediated by the enzyme EptA (formerly termed LptA) and promotes resistance to innate defense systems, induces the pro-inflammatory response and can influence the
fitness of bacteria during infection. These important biological properties have driven efforts dealing with the biochemistry and structural biology of EptA that will facilitate the development of potential inhibitors that block PEA addition to lipid A.
Context. One of the possible approaches to detecting optical counterparts of GRBs requires monitoring large parts of the sky. This idea has gained some instrumental support in recent years, such as ...with the “Pi of the Sky” project. The broad sky coverage of the “Pi of the Sky” apparatus results from using cameras with wide-angle lenses (20° × 20° field of view). Optics of this kind introduce significant deformations of the point spread function (PSF), increasing with the distance from the frame centre. A deformed PSF results in additional uncertainties in data analysis. Aims. Our aim was to create a model describing highly deformed PSF in optical astronomy, allowing uncertainties caused by image deformations to be reduced. Methods. Detailed laboratory measurements of PSF, pixel sensitivity, and pixel response functions were performed. These data were used to create an effective high quality polynomial model of the PSF. Finally, tuning the model and tests in applications to the real sky data were performed. Results. We have developed a PSF model that accurately describes even very deformed stars in our wide-field experiment. The model is suitable for use in any other experiment with similar image deformation, with a simple tuning of its parameters. Applying this model to astrometric procedures results in a significant improvement over standard methods, while basic photometry precision performed with the model is comparable to the results of an optimised aperture algorithm. Additionally, the model was used to search for a weak signal – namely a possible gamma ray burst optical precursor – showing very promising results. Conclusions. Precise modelling of the PSF function significantly improves the astrometric precision and enhances the discovery potential of a wide-field system with lens optics.
An apparatus to search for optical flashes in the sky is described. It has been optimized for optical counterparts of gamma ray bursts (GRB). It consists of 2×16 cameras covering all the sky. The sky ...is monitored continuously and the data are analyzed on-line. The apparatus has self-triggering capability and can react to external triggers with negative delay. The prototype with two cameras has been installed at Las Campanas (Chile) and is operational from July 2004. The paper presents the general idea of the experiment and describes the apparatus in detail. The performance of the prototype is briefly reviewed and perspectives for the future are outlined.
Despite the widespread effectiveness of pneumococcal conjugate vaccines on the overall incidence of invasive pneumococcal disease, the global epidemiological landscape continues to be transformed by ...residual disease from non-vaccine serotypes, thus highlighting the need for vaccines with expanded disease coverage. To address these needs, we have developed V116,an investigational 21-valent non-adjuvanted pneumococcal conjugate vaccine (PCV),containingpneumococcal polysaccharides (PnPs) 3, 6A, 7F, 8, 9N, 10A, 11A,12F, 15A, 16F, 17F, 19A, 20, 22F, 23A, 23B, 24F, 31, 33F, 35B, anda de-O-acetylated 15B(deOAc15B) individually conjugated to the nontoxic diphtheria toxoid CRM197 carrier protein. Preclinical studies evaluated the immunogenicity of V116 inadult monkeys, rabbits, and mice. Following one dose, V116 was found to be immunogenic in preclinical animal species and induced functional antibodies for all serotypes included in the vaccine, in addition to cross-reactive functional antibodies to serotypes 6C and 15B. In these preclinical animal studies, the increased valency of V116 did not result in serotype-specific antibody suppression when compared to lower valent vaccines V114 or PCV13. In addition, when compared with naïve controls, splenocytes from V116 to immunized animals demonstrated significant induction of CRM197-specific T cells in both IFN-γ and IL-4 ELISPOT assays, as well as Th1 and Th2 cytokine induction through in vitro stimulation assays, thus suggesting the ability of V116 to engage T cell dependent immune response pathways to aid in development of memory B cells. V116 also demonstrated significant protection in mice from intratracheal challenge with serotype 24F, a novel serotype not contained in any currently licensed vaccine.
We have evaluated the stability profiles of adenovirus type-5 (Ad5)-based vaccine formulations to identify liquid formulations that are stable during long-term storage at 4°C. By identifying the ...major physiochemical inactivation pathway(s) during storage, formulations of Ad5 were designed with specific pharmaceutical excipients leading to greatly enhanced stability. For example, results indicate that Ad5 is stabilized by non-ionic surfactants and cryoprotectants as well as excipients known to inhibit free-radical oxidation. A non-ionic surfactant is necessary to prevent adsorption of adenovirus to glass surfaces during storage, and a cryoprotectant is needed to prevent freeze−thaw-induced virus inactivation. In a base formulation (A105) containing sucrose as the cryoprotectant and polysorbate-80 as the non-ionic surfactant, metal-ion catalyzed free-radical oxidation is an important mechanism of Ad5 inactivation. The free-radical oxidation inhibitors ethanol and histidine, combined with the metal-ion chelator ethylenediaminetetraacetic acid (EDTA), were determined to be effective stabilizers of Ad5. Arrhenius plots of stability data are consistent with a first-order inactivation mechanism with apparent activation energies for virus inactivation of 26.5±0.9 and 28.7±0.6 kcal/mol in the absence and presence of free-radical oxidation inhibitors, respectively. Optimization of formulation pH, as well as the EDTA and ethanol concentrations, allowed for the identification of formulations that further enhanced long-term storage stability. For example, Ad5 in an optimized liquid formulation (A195) lost <0.1 logs of infectivity after 24 months of storage at 4°C. The immunogenicity of a recombinant Ad5-based human immunodeficiency virus (HIV) vaccine candidate expressing HIV-1 gag (MRKAd5gag) formulated in A195, was shown to be equivalent to the same vaccine formulated in A105. Therefore, the use of EDTA, ethanol, and histidine did not significantly alter the immunogenicity of the vaccine in mice. The identification of 4°C stable liquid formulations should significantly enhance the utility of Ad5 as a vector for vaccines and gene therapy.
Abstract Pneumococcal disease continues to be a medical need even with very effective vaccines on the market. Globally, there are extensive research efforts to improve serotype coverage with novel ...vaccines; therefore, conducting preclinical studies in different animal models becomes essential. The work presented herein focuses on evaluating a 15-valent pneumococcal conjugate vaccine (PCV15) in mice. Initially we evaluated several doses of PCV15 in Balb/c mice. The optimal vaccine dose was determined to be 0.4 μg per pneumococcal polysaccharide (PS) (0.8 μg of 6B) for subsequent studies. This PS dose was chosen for PCV evaluation in mice based on antibody levels determined by multiplexed electrochemiluminescent (ECL) assays, T-cell responses following in vitro stimulation with CRM197 peptides and protection from pneumococcal challenge. We then selected four mouse strains for evaluation: Balb/c, C3H/HeN, CD1 and Swiss Webster (SW), immunized with PCV15 by either intraperitoneal (IP) or intramuscular (IM) routes. We assessed IgG responses by ECL assays and functional antibody activity by multiplexed opsonophagocytic assays (MOPA). Every mouse strain evaluated responded to all 15 serotypes contained in the vaccine. Mice tended to have lower responses to serotypes 6B, 23F and 33F. The IP route of immunization resulted in higher antibody titers for most serotypes in Balb/c, C3H and SW. CD1 mice tended to respond similarly for most serotypes, regardless of route of immunization. Similar trends were observed with the four mouse strains when evaluating functional antibody activity. Given the differences in antibody responses based on mouse strain and route of immunization, it is critical to evaluate pneumococcal vaccines in multiple animal models to determine the optimal formulation before moving to clinical trials.
Long-duration gamma-ray bursts (GRBs) release copious amounts of energy across the entire electromagnetic spectrum, and so provide a window into the process of black hole formation from the collapse ...of massive stars. Previous early optical observations of even the most exceptional GRBs (990123 and 030329) lacked both the temporal resolution to probe the optical flash in detail and the accuracy needed to trace the transition from the prompt emission within the outflow to external shocks caused by interaction with the progenitor environment. Here we report observations of the extraordinarily bright prompt optical and gamma-ray emission of GRB 080319B that provide diagnostics within seconds of its formation, followed by broadband observations of the afterglow decay that continued for weeks. We show that the prompt emission stems from a single physical region, implying an extremely relativistic outflow that propagates within the narrow inner core of a two-component jet.
Issue Title: The Multi-Messenger Approach to High-Energy Gamma-Ray Sources: Third Workshop on the Nature of Unidentified High-Energy Sources Experiment "Pi of the Sky" is designed to search for ...prompt optical emission from GRB sources. 32 CCD cameras covering 2 steradians will monitor the sky continuously. The data will be analysed on-line in search for optical flashes. The prototype with 2 cameras operated at Las Campanas (Chile) since 2004 has recognised several outbursts of flaring stars and has given limits for a few GRB. PUBLICATION ABSTRACT
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