260 research outputs found

    Recent high resolution laboratory determinations of line broadening and intensity parameters: PH3, CH3D, and CO2

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    Recent unpublished laboratory work on rovibrational line strengths and broadening coefficients which is of interest in the study of planetary atmospheres was reviewed. The molecules discussed are PH3, CH3D and CO2

    Low-temperature gas opacity - AESOPUS: a versatile and quick computational tool

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    We introduce a new tool - AESOPUS: Accurate Equation of State and OPacity Utility Software - for computing the equation of state and the Rosseland mean (RM) opacities of matter in the ideal gas phase. Results are given as a function of one pair of state variables, (i.e. temperature T in the range 3.2 <= log(T) <= 4.5, and parameter R= rho/(T/10^6 K)^3 in the range -8 <= log(R) <= 1), and arbitrary chemical mixture. The chemistry is presently solved for about 800 species, consisting of almost 300 atomic and 500 molecular species. The gas opacities account for many continuum and discrete sources, including atomic opacities, molecular absorption bands, and collision-induced absorption. Several tests made on AESOPUS have proved that the new opacity tool is accurate in the results,flexible in the management of the input prescriptions, and agile in terms of computational time requirement. We set up a web-interface (http://stev.oapd.inaf.it/aesopus) which enables the user to compute and shortly retrieve RM opacity tables according to his/her specific needs, allowing a full degree of freedom in specifying the chemical composition of the gas. Useful applications may regard RM opacities of gas mixtures with i) scaled-solar abundances of metals, choosing among various solar mixture compilations available in the literature; ii) varying CNO abundances, suitable for evolutionary models of red and asymptotic giant branch stars and massive stars in the Wolf-Rayet stages; iii) various degrees of enhancement in alpha-elements, and C-N, Na-O and Mg-Al abundance anti-correlations, necessary to properly describe the properties of stars in early-type galaxies and Galactic globular clusters; iv) zero-metal abundances appropriate for studies of gas opacity in primordial conditions.Comment: 32 pages, 34 postscript figures, A&A in press; new section 4.1.2 showing first tests with stellar models, sections 2.2, 2.2.2 and 5 expanded; interactive web-page at http://stev.oapd.inaf.it/aesopu

    The puzzling dredge-up pattern in NGC 1978

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    Low-mass stars are element factories that efficiently release their products in the final stages of their evolution by means of stellar winds. Since they are large in number, they contribute significantly to the cosmic matter cycle. To assess this contribution quantitatively, it is crucial to obtain a detailed picture of the stellar interior, particularly with regard to nucleosynthesis and mixing mechanisms. We seek to benchmark stellar evolutionary models of low-mass stars. In particular, we measure the surface abundance of ^{12}C in thermally pulsing AGB stars with well-known mass and metallicity, which can be used to infer information about the onset and efficiency of the third dredge-up. We recorded high-resolution near-infrared spectra of AGB stars in the LMC cluster NGC 1978. The sample comprised both oxygen-rich and carbon-rich stars, and is well-constrained in terms of the stellar mass, metallicity, and age. We derived the C/O and ^{12}C/^{13}C ratio from the target spectra by a comparison to synthetic spectra. Then, we compared the outcomes of stellar evolutionary models with our measurements. The M stars in NGC 1978 show values of C/O and ^{12}C/^{13}C that can best be explained with moderate extra-mixing on the RGB coupled to a moderate oxygen enhancement in the chemical composition. These oxygen-rich stars do not seem to have undergone third dredge-up episodes (yet). The C stars show carbon-to-oxygen and carbon isotopic ratios consistent with the occurrence of the third dredge-up. We did not find S stars in this cluster. None of the theoretical schemes that we considered was able to reproduce the observations appropriately. Instead, we discuss some non-standard scenarios to explain the puzzling abundance pattern in NGC 1978.Comment: 16 pages, 9 figures, 4 tables, accepted for publication in A&A, language revise

    A Vaccine against CCR5 Protects a Subset of Macaques upon Intravaginal Challenge with Simian Immunodeficiency Virus SIVmac251

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    As an alternative to targeting human immunodeficiency virus (HIV), we have developed vaccines targeting CCR5, a self-protein critically involved in HIV replication and pathogenesis. By displaying peptides derived from CCR5 at high density on the surface of virus-like particles, we can efficiently induce high-titer IgG antibodies against this self-molecule. Here, we investigated whether prophylactic immunization of rhesus macaques with a particle-based vaccine targeting two regions of macaque CCR5 could prevent or suppress vaginal infection with highly virulent SIVmac251. Twelve macaques were vaccinated with a bacteriophage Qß-based vaccine targeting macaque CCR5 (Qß.CCR5). Six control animals were immunized with the Qß platform alone. All animals immunized with Qß.CCR5 developed high-titer anti-CCR5 antibody responses. Macaques were vaginally challenged with a high dose of SIVmac251. The mean peak viral RNA levels in the vaccinated groups were 30-fold lower than in the control group (106.8 versus 108.3 copies/ml plasma). Three of the 12 vaccinated macaques dramatically suppressed simian immunodeficiency virus (SIV) replication: peak viral loads were low (103 to 104 RNA copies/ml), and SIV RNA became undetectable from 6 weeks onward. No viral RNA or DNA could be detected in colon and lymph node biopsy specimens collected 13 months after challenge. In vivo depletion of CD8+ cells failed to induce a viral rebound. However, once anti-CCR5 antibody responses had waned, the 3 animals became infected after intravaginal and/or intravenous rechallenge. In conclusion, vaccination against CCR5 was associated with dramatic suppression of virus replication in a subset (25%) of macaques. These data support further research of vaccination against CCR5 to combat HIV infection

    A Pan-HPV Vaccine Based on Bacteriophage PP7 VLPs Displaying Broadly Cross-Neutralizing Epitopes from the HPV Minor Capsid Protein, L2

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    Current human papillomavirus (HPV) vaccines that are based on virus-like particles (VLPs) of the major capsid protein L1 largely elicit HPV type-specific antibody responses. In contrast, immunization with the HPV minor capsid protein L2 elicits antibodies that are broadly cross-neutralizing, suggesting that a vaccine targeting L2 could provide more comprehensive protection against infection by diverse HPV types. However, L2-based immunogens typically elicit much lower neutralizing antibody titers than L1 VLPs. We previously showed that a conserved broadly neutralizing epitope near the N-terminus of L2 is highly immunogenic when displayed on the surface of VLPs derived from the bacteriophage PP7. Here, we report the development of a panel of PP7 VLP-based vaccines targeting L2 that protect mice from infection with carcinogenic and non-carcinogenic HPV types that infect the genital tract and skin.L2 peptides from eight different HPV types were displayed on the surface of PP7 bacteriophage VLPs. These recombinant L2 VLPs, both individually and in combination, elicited high-titer anti-L2 IgG serum antibodies. Immunized mice were protected from high dose infection with HPV pseudovirus (PsV) encapsidating a luciferase reporter. Mice immunized with 16L2 PP7 VLPs or 18L2 PP7 VLPs were nearly completely protected from both PsV16 and PsV18 challenge. Mice immunized with the mixture of eight L2 VLPs were strongly protected from genital challenge with PsVs representing eight diverse HPV types and cutaneous challenge with HPV5 PsV.VLP-display of a cross-neutralizing HPV L2 epitope is an effective approach for inducing high-titer protective neutralizing antibodies and is capable of offering protection from a spectrum of HPVs associated with cervical cancer as well as genital and cutaneous warts

    Plant virus particles carrying tumour antigen activate TLR7 and induce high levels of protective antibody

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    Induction of potent antibody is the goal of many vaccines targeted against infections or cancer. Modern vaccine designs that use virus-like particles (VLP) have shown efficacy for prophylactic vaccination against virus-associated cancer in the clinic. Here we used plant viral particles (PVP), which are structurally analogous to VLP, coupled to a weak idiotypic (Id) tumour antigen, as a conjugate vaccine to induce antibody against a murine B-cell malignancy. The Id-PVP vaccine incorporates a natural adjuvant, the viral ssRNA, which acts via TLR7. It induced potent protective anti-Id antibody responses in an in vivo mouse model, superior to the "gold standard" Id vaccine, with prevalence of the IgG2a isotype. Combination with alum further increased antibody levels and maintained the IgG2a bias. Engagement of TLR7 in vivo was followed by secretion of IFN-? by plasmacytoid dendritic cells and by activation of splenic CD11chi conventional dendritic cells. The latter was apparent from up-regulation of co-stimulatory molecules and from secretion of a wide range of inflammatory cytokines and chemokines including the Th1-governing cytokine IL-12, in keeping with the IgG2a antibody isotype distribution. PVP conjugates are a novel cancer vaccine design, offering an attractive molecular form, similar to VLP, and providing T-cell help. In contrast to VLP, they also incorporate a safe "in-built" ssRNA adjuvant

    Natural anti-CCR5 antibodies in HIV-infection and -exposure

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    Natural antibodies constitute a first-line of defence against pathogens; they may also play other roles in immune regulation and homeostasis, through their ability to bind host antigens, surface molecules and receptors. Natural anti-CCR5 antibodies can be decisive in preventing HIV infection in mucosal tissues and offer prompt and effective protection just at major sites of virus entry. Among natural anti-CCR5 antibodies, IgG and IgA to the ECL1 domain have been shown to block HIV effectively and durably without causing harm to the host. Their biological properties and their uncommon generation in subsets of HIV-infected and HIV-exposed individuals (so called ESN) will be introduced and discussed, with the aim at exploiting their potential in therapy and prevention

    Oxidized and Aggregated Recombinant Human Interferon Beta is Immunogenic in Human Interferon Beta Transgenic Mice

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    PurposeTo study the effect of oxidation on the structure of recombinant human interferon beta-1a (rhIFNβ-1a) and its immunogenicity in wild-type and immune-tolerant transgenic mice.MethodsUntreated rhIFNβ-1a was degraded by metal-catalyzed oxidation, H2O2-mediated oxidation, and guanidine-mediated unfolding/refolding. Four rhIFNβ-1a preparations with different levels of oxidation and aggregation were injected intraperitoneally in mice 15× during 3 weeks. Both binding and neutralizing antibodies were measured.ResultsAll rhIFNβ-1a preparations contained substantial amounts of aggregates. Metal-catalyzed oxidized rhIFNβ-1a contained high levels of covalent aggregates as compared with untreated rhIFNβ-1a. H2O2-treated rhIFNβ-1a showed an increase in oligomer and unrecovered protein content by HP-SEC; RP-HPLC revealed protein oxidation. Guanidine-treated rhIFNβ-1a mostly consisted of dimers and oligomers and some non-covalent aggregates smaller in size than those in untreated rhIFNβ-1a. All degraded samples showed alterations in tertiary protein structure. Wild-type mice showed equally high antibody responses against all preparations. Transgenic mice were discriminative, showing elevated antibody responses against both metal-catalyzed oxidized and H2O2-treated rhIFNβ-1a as compared to untreated and guanidine-treated rhIFNβ-1a.ConclusionsOxidation-mediated aggregation increased the immunogenicity of rhIFNβ-1a in transgenic mice, whereas aggregated preparations devoid of measurable oxidation levels were hardly immunogenic
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