296 research outputs found

    The Plasma and Suprathermal Ion Composition (PLASTIC) investigation on the STEREO observatories

    Get PDF
    The Plasma and Suprathermal Ion Composition (PLASTIC) investigation provides the in situ solar wind and low energy heliospheric ion measurements for the NASA Solar Terrestrial Relations Observatory Mission, which consists of two spacecraft (STEREO-A, STEREO-B). PLASTIC-A and PLASTIC-B are identical. Each PLASTIC is a time-of-flight/energy mass spectrometer designed to determine the elemental composition, ionic charge states, and bulk flow parameters of major solar wind ions in the mass range from hydrogen to iron. PLASTIC has nearly complete angular coverage in the ecliptic plane and an energy range from ∼0.3 to 80 keV/e, from which the distribution functions of suprathermal ions, including those ions created in pick-up and local shock acceleration processes, are also provided

    Meningococcal Factor H Binding Proteins in Epidemic Strains from Africa: Implications for Vaccine Development

    Get PDF
    Epidemics of meningococcal meningitis are common in sub-Saharan Africa. Most are caused by encapsulated serogroup A strains, which rarely cause disease in industrialized countries. A serogroup A polysaccharide protein conjugate vaccine recently was introduced in some countries in sub-Saharan Africa. The antibodies induced, however, may allow replacement of serogroup A strains with serogroup W-135 or X strains, which also cause epidemics in this region. Protein antigens, such as factor H binding protein (fHbp), are promising for prevention of meningococcal serogroup B disease. These proteins also are present in strains with other capsular serogroups. Here we report investigation of the potential of fHbp vaccines for prevention of disease caused by serogroup A, W-135 and X strains from Africa. Four fHbp amino acid sequence variants accounted for 81% of the 106 African isolates studied. While there was little cross-protective activity by antibodies elicited in mice by recombinant fHbp vaccines from each of the four sequence variants, a prototype native outer membrane vesicle (NOMV) vaccine from a mutant with over-expressed fHbp elicited antibodies with broad protective activity. A NOMV vaccine has the potential to supplement coverage by the group A conjugate vaccine and help prevent emergence of disease caused by non-serogroup A strains

    Age-Related Immunity to Meningococcal Serogroup C Vaccination: An Increase in the Persistence of IgG2 Correlates with a Decrease in the Avidity of IgG

    Get PDF
    Contains fulltext : 97618.pdf (publisher's version ) (Open Access)Background All children and adolescents between 1 and 19 years of age in The Netherlands received a single meningococcal serogroup C conjugate (MenCC) vaccine in 2002. During follow-up 4–5 years later, the persistence of MenC polysaccharide-specific IgG was found to be dependent on age of vaccination with higher IgG levels in the oldest immunized age categories. Methods and Findings Two cross-sectional population-based serum banks, collected in 1995/1996 and in 2006/2007, were used for this study. We measured MenC polysaccharide-specific IgM, the IgG1 and IgG2 subclasses and determined the avidity of the IgG antibodies. We report that the age-related persistence of IgG after immunization with the MenCC vaccine seemed to result from an increase of IgG2 levels with age, while IgG1 levels remained stable throughout the different age-cohorts. Furthermore, an age-related increase in IgM levels was observed, correlating with the persistence of IgG antibodies with age. It is noteworthy that the increase in IgG2 correlated with a reduced IgG-avidity with age. Conclusion These date indicate that the classical characteristics of a T-cell-dependent antibody response as elicited by protein based vaccines might not be completely applicable when conjugate vaccines are administered to older children and adolescents up to 18 years of age. The response elicited by the MenCC vaccine seemed to be more a mixture of both T cell dependent and T cell independent responses in terms of humoral immunological characteristics

    The Meningococcal Vaccine Candidate Neisserial Surface Protein A (NspA) Binds to Factor H and Enhances Meningococcal Resistance to Complement

    Get PDF
    Complement forms an important arm of innate immunity against invasive meningococcal infections. Binding of the alternative complement pathway inhibitor factor H (fH) to fH-binding protein (fHbp) is one mechanism meningococci employ to limit complement activation on the bacterial surface. fHbp is a leading vaccine candidate against group B Neisseria meningitidis. Novel mechanisms that meningococci employ to bind fH could undermine the efficacy of fHbp-based vaccines. We observed that fHbp deletion mutants of some meningococcal strains showed residual fH binding suggesting the presence of a second receptor for fH. Ligand overlay immunoblotting using membrane fractions from one such strain showed that fH bound to a ∼17 kD protein, identified by MALDI-TOF analysis as Neisserial surface protein A (NspA), a meningococcal vaccine candidate whose function has not been defined. Deleting nspA, in the background of fHbp deletion mutants, abrogated fH binding and mAbs against NspA blocked fH binding, confirming NspA as a fH binding molecule on intact bacteria. NspA expression levels vary among strains and expression correlated with the level of fH binding; over-expressing NspA enhanced fH binding to bacteria. Progressive truncation of the heptose (Hep) I chain of lipooligosaccharide (LOS), or sialylation of lacto-N-neotetraose LOS both increased fH binding to NspA-expressing meningococci, while expression of capsule reduced fH binding to the strains tested. Similar to fHbp, binding of NspA to fH was human-specific and occurred through fH domains 6–7. Consistent with its ability to bind fH, deleting NspA increased C3 deposition and resulted in increased complement-dependent killing. Collectively, these data identify a key complement evasion mechanism with important implications for ongoing efforts to develop meningococcal vaccines that employ fHbp as one of its components

    Immunoglobulin GM 3 23 5,13,14 phenotype is strongly associated with IgG1 antibody responses to Plasmodium vivax vaccine candidate antigens PvMSP1-19 and PvAMA-1

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Humoral immune responses play a key role in the development of immunity to malaria, but the host genetic factors that contribute to the naturally occurring immune responses to malarial antigens are not completely understood. The aim of the present investigation was to determine whether, in subjects exposed to malaria, GM and KM allotypes--genetic markers of immunoglobulin γ and κ-type light chains, respectively--contribute to the magnitude of natural antibody responses to target antigens that are leading vaccine candidates for protection against <it>Plasmodium vivax</it>.</p> <p>Methods</p> <p>Sera from 210 adults, who had been exposed to malaria transmission in the Brazilian Amazon endemic area, were allotyped for several GM and KM determinants by a standard hemagglutination-inhibition method. IgG subclass antibodies to <it>P. vivax </it>apical membrane antigen 1 (PvAMA-1) and merozoite surface protein 1 (PvMSP1-19) were determined by an enzyme-linked immunosorbent assay. Multiple linear regression models and the non-parametric Mann-Whitney test were used for data analyses.</p> <p>Results</p> <p>IgG1 antibody levels to both PvMSP1-19 and PvAMA-1 antigens were significantly higher (<it>P </it>= 0.004, <it>P </it>= 0.002, respectively) in subjects with the GM 3 23 5,13,14 phenotype than in those who lacked this phenotype.</p> <p>Conclusions</p> <p>Results presented here show that immunoglobulin GM allotypes contribute to the natural antibody responses to <it>P. vivax </it>malaria antigens. These findings have important implications for the effectiveness of vaccines containing PvAMA-1 or PvMSP1-19 antigens. They also shed light on the possible role of malaria as one of the evolutionary selective forces that may have contributed to the maintenance of the extensive polymorphism at the GM loci.</p

    Experimental Meningococcal Sepsis in Congenic Transgenic Mice Expressing Human Transferrin

    Get PDF
    Severe meningococcal sepsis is still of high morbidity and mortality. Its management may be improved by an experimental model allowing better understanding of its pathophysiology. We developed an animal model of meningococcal sepsis in transgenic BALB/c mice expressing human transferrin. We studied experimental meningococcal sepsis in congenic transgenic BALB/c mice expressing human transferrin by transcriptional profiling using microarray analysis of blood and brain samples. Genes encoding acute phase proteins, chemokines and cytokines constituted the largest strongly regulated groups. Dynamic bioluminescence imaging further showed high blood bacterial loads that were further enhanced after a primary viral infection by influenza A virus. Moreover, IL-1 receptor–associated kinase–3 (IRAK-3) was induced in infected mice. IRAK-3 is a negative regulator of Toll-dependant signaling and its induction may impair innate immunity and hence result in an immunocompromised state allowing bacterial survival and systemic spread during sepsis. This new approach should enable detailed analysis of the pathophysiology of meningococcal sepsis and its relationships with flu infection

    The Irredeemable Debt: On the English Translation of Lacan's First Two Public Seminars

    Get PDF
    This is an Accepted Manuscript of an article published by Edinburgh University Press in Psychoanalysis and History . The Version of Record is available online at: https://www.euppublishing.com/doi/10.3366/pah.2017.0214Drawing on archival sources and personal recollections, this essay reconstructs the troubled history of the first robust attempt at making the works of the French psychoanalyst Jacques Lacan newly available to an anglophone readership, after his death in 1981. It details how the project was initiated by John Forrester as part of a large-scale initiative to generate translations of both Lacan’s own texts and seminars, and various books written in the Lacanian tradition. If, almost seven years after it was conceived, Forrester’s project only resulted in the publication of English translations of Lacan’s first two public seminars, the essay demonstrates that this was not owing to disagreements over the quality of Forrester’s work, but because of two consecutive sources of resistance. External resistance from publishers first led to the initial project being reduced to the translation of two seminars, whereas internal resistance from Lacan’s son-in-law Jacques-Alain Miller to Forrester’s vision of presenting the seminars with a full scholarly apparatus subsequently brought about delays in its execution
    corecore