474 research outputs found

    Live SIV vaccine correlate of protection: immune complex-inhibitory Fc receptor interactions that reduce target cell availability

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    Principles to guide design of an effective vaccine against HIV are greatly needed, particularly to protect women in the pandemic’s epicentre in Africa. We have been seeking these principles by identifying correlates of the robust protection associated with SIVmac239Δnef vaccination in the SIV-rhesus macaque animal model of HIV-1 transmission to women. We have identified one correlate of SIVmac239Δnef protection against vaginal challenge as a resident mucosal system for SIV-gp41 trimer antibody production and neonatal Fc receptor (FcRn)-mediated concentration of these antibodies on the path of virus entry to inhibit establishment of infected founder populations at the portal of entry. Here we identify as a second protection correlate, blocking CD4+ T cell recruitment to inhibit local expansion of infected founder populations. Virus-specific immune complex interactions with the inhibitory FcγRIIb receptor in the epithelium lining the cervix initiate expression of genes that block recruitment of target cells to fuel local expansion. Immune complex-FcγRIIb receptor interactions at mucosal frontlines to dampen the innate immune response to vaginal challenge could be a potentially general mechanism for the mucosal immune system to sense and modulate the response to a previously encountered pathogen. Designing vaccines to provide protection without eliciting these transmission-promoting innate responses could contribute to developing an effective HIV-1 vaccine

    Live SIV vaccine correlate of protection: immune complex-inhibitory Fc receptor interactions that reduce target cell availability

    Get PDF
    Principles to guide design of an effective vaccine against HIV are greatly needed, particularly to protect women in the pandemic’s epicentre in Africa. We have been seeking these principles by identifying correlates of the robust protection associated with SIVmac239Δnef vaccination in the SIV-rhesus macaque animal model of HIV-1 transmission to women. We have identified one correlate of SIVmac239Δnef protection against vaginal challenge as a resident mucosal system for SIV-gp41 trimer antibody production and neonatal Fc receptor (FcRn)-mediated concentration of these antibodies on the path of virus entry to inhibit establishment of infected founder populations at the portal of entry. Here we identify as a second protection correlate, blocking CD4+ T cell recruitment to inhibit local expansion of infected founder populations. Virus-specific immune complex interactions with the inhibitory FcγRIIb receptor in the epithelium lining the cervix initiate expression of genes that block recruitment of target cells to fuel local expansion. Immune complex-FcγRIIb receptor interactions at mucosal frontlines to dampen the innate immune response to vaginal challenge could be a potentially general mechanism for the mucosal immune system to sense and modulate the response to a previously encountered pathogen. Designing vaccines to provide protection without eliciting these transmission-promoting innate responses could contribute to developing an effective HIV-1 vaccine

    A Measurement of the Electric Form Factor of the Neutron through d(e,en)p\vec{d}(\vec{e},e'n)p at Q2=0.5Q^2 = 0.5 (GeV/c)2^2

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    We report the first measurement of the neutron electric form factor GEnG_E^n via d(e,en)p\vec{d}(\vec{e},e'n)p using a solid polarized target. GEnG_E^n was determined from the beam-target asymmetry in the scattering of longitudinally polarized electrons from polarized deuterated ammonia, 15^{15}ND3_3. The measurement was performed in Hall C at Thomas Jefferson National Accelerator Facility (TJNAF) in quasi free kinematics with the target polarization perpendicular to the momentum transfer. The electrons were detected in a magnetic spectrometer in coincidence with neutrons in a large solid angle segmented detector. We find GEn=0.04632±0.00616(stat.)±0.00341(syst.)G_E^n = 0.04632\pm0.00616 (stat.) \pm0.00341 (syst.) at Q2=0.495Q^2 = 0.495 (GeV/c)2^2.Comment: Latex2e 5 pages, 3 figure

    Functional Expression of Human Adenine Nucleotide Translocase 4 in Saccharomyces Cerevisiae

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    The adenine nucleotide translocase (ANT) mediates the exchange of ADP and ATP across the inner mitochondrial membrane. The human genome encodes multiple ANT isoforms that are expressed in a tissue-specific manner. Recently a novel germ cell-specific member of the ANT family, ANT4 (SLC25A31) was identified. Although it is known that targeted depletion of ANT4 in mice resulted in male infertility, the functional biochemical differences between ANT4 and other somatic ANT isoforms remain undetermined. To gain insight into ANT4, we expressed human ANT4 (hANT4) in yeast mitochondria. Unlike the somatic ANT proteins, expression of hANT4 failed to complement an AAC-deficient yeast strain for growth on media requiring mitochondrial respiration. Moreover, overexpression of hANT4 from a multi-copy plasmid interfered with optimal yeast growth. However, mutation of specific amino acids of hANT4 improved yeast mitochondrial expression and supported growth of the AAC-deficient yeast on non-fermentable carbon sources. The mutations affected amino acids predicted to interact with phospholipids, suggesting the importance of lipid interactions for function of this protein. Each mutant hANT4 and the somatic hANTs exhibited similar ADP/ATP exchange kinetics. These data define common and distinct biochemical characteristics of ANT4 in comparison to ANT1, 2 and 3 providing a basis for study of its unique adaptation to germ cells

    Conjugative Plasmids of Neisseria gonorrhoeae

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    Many clinical isolates of the human pathogen Neisseria gonorrhoeae contain conjugative plasmids. The host range of these plasmids is limited to Neisseria species, but presence of a tetracycline (tetM) determinant inserted in several of these plasmids is an important cause of the rapid spread of tetracycline resistance. Previously plasmids with different backbones (Dutch and American type backbones) and with and without different tetM determinants (Dutch and American type tetM determinants) have been identified. Within the isolates tested, all plasmids with American or Dutch type tetM determinants contained a Dutch type plasmid backbone. This demonstrated that tetM determinants should not be used to differentiate between conjugal plasmid backbones. The nucleotide sequences of conjugative plasmids with Dutch type plasmid backbones either not containing the tetM determinant (pEP5233) or containing Dutch (pEP5289) or American (pEP5050) type tetM determinants were determined. Analysis of the backbone sequences showed that they belong to a novel IncP1 subfamily divergent from the IncP1α, β, γ, δ and ε subfamilies. The tetM determinants were inserted in a genetic load region found in all these plasmids. Insertion was accompanied by the insertion of a gene with an unknown function, and rearrangement of a toxin/antitoxin gene cluster. The genetic load region contains two toxin/antitoxins of the Zeta/Epsilon toxin/antitoxin family previously only found in Gram positive organisms and the virulence associated protein D of the VapD/VapX toxin/antitoxin family. Remarkably, presence of VapX of pJD1, a small cryptic neisserial plasmid, in the acceptor strain strongly increased the conjugation efficiency, suggesting that it functions as an antitoxin for the conjugative plasmid. The presence of the toxin and antitoxin on different plasmids might explain why the host range of this IncP1 plasmid is limited to Neisseria species. The isolated plasmids conjugated efficiently between N. gonorrhoeae strains, but did not enhance transfer of a genetic marker

    Use of antenatal services and delivery care among women in rural western Kenya: a community based survey

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    BACKGROUND: Improving maternal health is one of the UN Millennium Development Goals. We assessed provision and use of antenatal services and delivery care among women in rural Kenya to determine whether women were receiving appropriate care. METHODS: Population-based cross-sectional survey among women who had recently delivered. RESULTS: Of 635 participants, 90% visited the antenatal clinic (ANC) at least once during their last pregnancy (median number of visits 4). Most women (64%) first visited the ANC in the third trimester; a perceived lack of quality in the ANC was associated with a late first ANC visit (Odds ratio [OR] 1.5, 95% confidence interval [CI] 1.0–2.4). Women who did not visit an ANC were more likely to have < 8 years of education (adjusted OR [AOR] 3.0, 95% CI 1.5–6.0), and a low socio-economic status (SES) (AOR 2.8, 95% CI 1.5–5.3). The ANC provision of abdominal palpation, tetanus vaccination and weight measurement were high (>90%), but provision of other services was low, e.g. malaria prevention (21%), iron (53%) and folate (44%) supplementation, syphilis testing (19.4%) and health talks (14.4%). Eighty percent of women delivered outside a health facility; among these, traditional birth attendants assisted 42%, laypersons assisted 36%, while 22% received no assistance. Factors significantly associated with giving birth outside a health facility included: age ≥ 30 years, parity ≥ 5, low SES, < 8 years of education, and > 1 hour walking distance from the health facility. Women who delivered unassisted were more likely to be of parity ≥ 5 (AOR 5.7, 95% CI 2.8–11.6). CONCLUSION: In this rural area, usage of the ANC was high, but this opportunity to deliver important health services was not fully utilized. Use of professional delivery services was low, and almost 1 out of 5 women delivered unassisted. There is an urgent need to improve this dangerous situation

    A novel formulation of inhaled sodium cromoglicate (PA101) in idiopathic pulmonary fibrosis and chronic cough: a randomised, double-blind, proof-of-concept, phase 2 trial

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    Background Cough can be a debilitating symptom of idiopathic pulmonary fibrosis (IPF) and is difficult to treat. PA101 is a novel formulation of sodium cromoglicate delivered via a high-efficiency eFlow nebuliser that achieves significantly higher drug deposition in the lung compared with the existing formulations. We aimed to test the efficacy and safety of inhaled PA101 in patients with IPF and chronic cough and, to explore the antitussive mechanism of PA101, patients with chronic idiopathic cough (CIC) were also studied. Methods This pilot, proof-of-concept study consisted of a randomised, double-blind, placebo-controlled trial in patients with IPF and chronic cough and a parallel study of similar design in patients with CIC. Participants with IPF and chronic cough recruited from seven centres in the UK and the Netherlands were randomly assigned (1:1, using a computer-generated randomisation schedule) by site staff to receive PA101 (40 mg) or matching placebo three times a day via oral inhalation for 2 weeks, followed by a 2 week washout, and then crossed over to the other arm. Study participants, investigators, study staff, and the sponsor were masked to group assignment until all participants had completed the study. The primary efficacy endpoint was change from baseline in objective daytime cough frequency (from 24 h acoustic recording, Leicester Cough Monitor). The primary efficacy analysis included all participants who received at least one dose of study drug and had at least one post-baseline efficacy measurement. Safety analysis included all those who took at least one dose of study drug. In the second cohort, participants with CIC were randomly assigned in a study across four centres with similar design and endpoints. The study was registered with ClinicalTrials.gov (NCT02412020) and the EU Clinical Trials Register (EudraCT Number 2014-004025-40) and both cohorts are closed to new participants. Findings Between Feb 13, 2015, and Feb 2, 2016, 24 participants with IPF were randomly assigned to treatment groups. 28 participants with CIC were enrolled during the same period and 27 received study treatment. In patients with IPF, PA101 reduced daytime cough frequency by 31·1% at day 14 compared with placebo; daytime cough frequency decreased from a mean 55 (SD 55) coughs per h at baseline to 39 (29) coughs per h at day 14 following treatment with PA101, versus 51 (37) coughs per h at baseline to 52 (40) cough per h following placebo treatment (ratio of least-squares [LS] means 0·67, 95% CI 0·48–0·94, p=0·0241). By contrast, no treatment benefit for PA101 was observed in the CIC cohort; mean reduction of daytime cough frequency at day 14 for PA101 adjusted for placebo was 6·2% (ratio of LS means 1·27, 0·78–2·06, p=0·31). PA101 was well tolerated in both cohorts. The incidence of adverse events was similar between PA101 and placebo treatments, most adverse events were mild in severity, and no severe adverse events or serious adverse events were reported. Interpretation This study suggests that the mechanism of cough in IPF might be disease specific. Inhaled PA101 could be a treatment option for chronic cough in patients with IPF and warrants further investigation

    A framework for evolutionary systems biology

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    <p>Abstract</p> <p>Background</p> <p>Many difficult problems in evolutionary genomics are related to mutations that have weak effects on fitness, as the consequences of mutations with large effects are often simple to predict. Current systems biology has accumulated much data on mutations with large effects and can predict the properties of knockout mutants in some systems. However experimental methods are too insensitive to observe small effects.</p> <p>Results</p> <p>Here I propose a novel framework that brings together evolutionary theory and current systems biology approaches in order to quantify small effects of mutations and their epistatic interactions <it>in silico</it>. Central to this approach is the definition of fitness correlates that can be computed in some current systems biology models employing the rigorous algorithms that are at the core of much work in computational systems biology. The framework exploits synergies between the realism of such models and the need to understand real systems in evolutionary theory. This framework can address many longstanding topics in evolutionary biology by defining various 'levels' of the adaptive landscape. Addressed topics include the distribution of mutational effects on fitness, as well as the nature of advantageous mutations, epistasis and robustness. Combining corresponding parameter estimates with population genetics models raises the possibility of testing evolutionary hypotheses at a new level of realism.</p> <p>Conclusion</p> <p>EvoSysBio is expected to lead to a more detailed understanding of the fundamental principles of life by combining knowledge about well-known biological systems from several disciplines. This will benefit both evolutionary theory and current systems biology. Understanding robustness by analysing distributions of mutational effects and epistasis is pivotal for drug design, cancer research, responsible genetic engineering in synthetic biology and many other practical applications.</p

    Determinants of recovery from post-COVID-19 dyspnoea: analysis of UK prospective cohorts of hospitalised COVID-19 patients and community-based controls

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    Background The risk factors for recovery from COVID-19 dyspnoea are poorly understood. We investigated determinants of recovery from dyspnoea in adults with COVID-19 and compared these to determinants of recovery from non-COVID-19 dyspnoea. Methods We used data from two prospective cohort studies: PHOSP-COVID (patients hospitalised between March 2020 and April 2021 with COVID-19) and COVIDENCE UK (community cohort studied over the same time period). PHOSP-COVID data were collected during hospitalisation and at 5-month and 1-year follow-up visits. COVIDENCE UK data were obtained through baseline and monthly online questionnaires. Dyspnoea was measured in both cohorts with the Medical Research Council Dyspnoea Scale. We used multivariable logistic regression to identify determinants associated with a reduction in dyspnoea between 5-month and 1-year follow-up. Findings We included 990 PHOSP-COVID and 3309 COVIDENCE UK participants. We observed higher odds of improvement between 5-month and 1-year follow-up among PHOSP-COVID participants who were younger (odds ratio 1.02 per year, 95% CI 1.01–1.03), male (1.54, 1.16–2.04), neither obese nor severely obese (1.82, 1.06–3.13 and 4.19, 2.14–8.19, respectively), had no pre-existing anxiety or depression (1.56, 1.09–2.22) or cardiovascular disease (1.33, 1.00–1.79), and shorter hospital admission (1.01 per day, 1.00–1.02). Similar associations were found in those recovering from non-COVID-19 dyspnoea, excluding age (and length of hospital admission). Interpretation Factors associated with dyspnoea recovery at 1-year post-discharge among patients hospitalised with COVID-19 were similar to those among community controls without COVID-19. Funding PHOSP-COVID is supported by a grant from the MRC-UK Research and Innovation and the Department of Health and Social Care through the National Institute for Health Research (NIHR) rapid response panel to tackle COVID-19. The views expressed in the publication are those of the author(s) and not necessarily those of the National Health Service (NHS), the NIHR or the Department of Health and Social Care. COVIDENCE UK is supported by the UK Research and Innovation, the National Institute for Health Research, and Barts Charity. The views expressed are those of the authors and not necessarily those of the funders
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