Hybrid spreading mechanisms and T cell activation shape the dynamics of HIV-1 infection

HIV-1 can disseminate between susceptible cells by two mechanisms: cell-free infection following fluid-phase diffusion of virions and by highly-efficient direct cell-to-cell transmission at immune cell contacts. The contribution of this hybrid spreading mechanism, which is also a characteristic of some important computer worm outbreaks, to HIV-1 progression in vivo remains unknown. Here we present a new mathematical model that explicitly incorporates the ability of HIV-1 to use hybrid spreading mechanisms and evaluate the consequences for HIV-1 pathogenenesis. The model captures the major phases of the HIV-1 infection course of a cohort of treatment naive patients and also accurately predicts the results of the Short Pulse Anti-Retroviral Therapy at Seroconversion (SPARTAC) trial. Using this model we find that hybrid spreading is critical to seed and establish infection, and that cell-to-cell spread and increased CD4+ T cell activation are important for HIV-1 progression. Notably, the model predicts that cell-to-cell spread becomes increasingly effective as infection progresses and thus may present a considerable treatment barrier. Deriving predictions of various treatments' influence on HIV-1 progression highlights the importance of earlier intervention and suggests that treatments effectively targeting cell-to-cell HIV-1 spread can delay progression to AIDS. This study suggests that hybrid spreading is a fundamental feature of HIV infection, and provides the mathematical framework incorporating this feature with which to evaluate future therapeutic strategies

Revisión de las principales tecnologías de purificación de biogás

As it is necessary to propose a sustainable change in Argentinean energy matrix is important to study new sources of energy production to reduce dependency of hydrocarbons. Those compounds are not only in short supply but also its combustion produces greenhouse gases. Biogas is a valuable renewable fuel obtained from organic waste materials solving contamination problems and reducing greenhouse gases. Methane and carbon dioxide are its main components, but biogas also contains contaminants such as hydrogen sulphide and siloxanes. The presence of these compounds different than methane constitutes a problem because they are detrimental to any biogas processing equipment and they generate harmful emissions. Then, it is important to include biogas purification before its final use. This paper reviews the state of the art in biogas purification. A promising purification methods is absorption in aqueous solutions because it is economical and works for carbon dioxide and hydrogen sulphide removal. The paper presents an analysis of biogas purification processes showing its applicability.Fil: Morero, Betzabet del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico Para la Industria Química (i); Argentina. Universidad Nacional del Litoral; ArgentinaFil: Groppelli, Eduardo. Universidad Nacional del Litoral. Facultad de Ingeniería Química; ArgentinaFil: Campanella, Enrique Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química (i); Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; Argentin

Comparación de diferentes soluciones de aminas para la purificación de biogás

El biogás es un valioso combustible renovable producido por la digestión anaeróbica de materia orgánica desechable. Sus principales componentes son metano (CH4), dióxido de carbono (CO2), agua (H2O) y ácido sulfhídrico (H2S). La presencia de anhídrido carbónico y ácido sulfhídrico constituye un problema ya que son perjudiciales para cualquier equipo de procesamiento de biogás y producen emisiones contaminantes. Entre las diversas tecnologías disponibles actualmente para purificar biogás, la absorción con aminas es una tecnología muy conveniente por su alta selectividad hacia el CO2 y el H2S. El presente trabajo compara la concentración de metano, anhídrido carbónico y ácido sulfhídrico en el gas endulzado y el consumo de energía en un proceso convencional de absorción-desorción para seis tipos de soluciones de aminas o mezclas de ellas.Fil: Morero, Betzabet del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Croquer Martinis, Carolina. Bryan Research & Engineering; Estados UnidosFil: Groppelli, Eduardo Santiago. Universidad Nacional del Litoral; ArgentinaFil: Campanella, Enrique Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Picornavirus RNA is protected from cleavage by ribonuclease during virion uncoating and transfer across cellular and model membranes

Picornaviruses are non-enveloped RNA viruses that enter cells via receptor-mediated endocytosis. Because they lack an envelope, picornaviruses face the challenge of delivering their RNA genomes across the membrane of the endocytic vesicle into the cytoplasm to initiate infection. Currently, the mechanism of genome release and translocation across membranes remains poorly understood. Within the enterovirus genus, poliovirus, rhinovirus 2, and rhinovirus 16 have been proposed to release their genomes across intact endosomal membranes through virally induced pores, whereas one study has proposed that rhinovirus 14 releases its RNA following disruption of endosomal membranes. For the more distantly related aphthovirus genus (e.g. foot-and-mouth disease viruses and equine rhinitis A virus) acidification of endosomes results in the disassembly of the virion into pentamers and in the release of the viral RNA into the lumen of the endosome, but no details have been elucidated as how the RNA crosses the vesicle membrane. However, more recent studies suggest aphthovirus RNA is released from intact particles and the dissociation to pentamers may be a late event. In this study we have investigated the RNase A sensitivity of genome translocation of poliovirus using a receptor-decorated-liposome model and the sensitivity of infection of poliovirus and equine-rhinitis A virus to co-internalized RNase A. We show that poliovirus genome translocation is insensitive to RNase A and results in little or no release into the medium in the liposome model. We also show that infectivity is not reduced by co-internalized RNase A for poliovirus and equine rhinitis A virus. Additionally, we show that all poliovirus genomes that are internalized into cells, not just those resulting in infection, are protected from RNase A. These results support a finely coordinated, directional model of viral RNA delivery that involves viral proteins and cellular membranes

Immune adaptor ADAP in T cells regulates HIV-1 transcription and cell-cell viral spread via different co-receptors

Background: Immune cell adaptor protein ADAP (adhesion and degranulation-promoting adaptor protein) mediates aspects of T-cell adhesion and proliferation. Despite this, a connection between ADAP and infection by the HIV-1 (human immunodeficiency virus-1) has not been explored. Results: In this paper, we show for the first time that ADAP and its binding to SLP-76 (SH2 domain-containing leukocyte protein of 76 kDa) regulate HIV-1 infection via two distinct mechanisms and co-receptors. siRNA down-regulation of ADAP, or expression of a mutant that is defective in associating to its binding partner SLP-76 (termed M12), inhibited the propagation of HIV-1 in T-cell lines and primary human T-cells. In one step, ADAP and its binding to SLP-76 were needed for the activation of NF-κB and its transcription of the HIV-1 long terminal repeat (LTR) in cooperation with ligation of co-receptor CD28, but not LFA-1. In a second step, the ADAP-SLP-76 module cooperated with LFA-1 to regulate conjugate formation between T-cells and dendritic cells or other T-cells as well as the development of the virological synapse (VS) and viral spread between immune cells. Conclusions: These findings indicate that ADAP regulates two steps of HIV-1 infection cooperatively with two distinct receptors, and as such, serves as a new potential target in the blockade of HIV-1 infection

Evaluation of future hydrological cycle under climate change scenarios in a mesoscale Alpine watershed of Italy

Abstract. We investigate future (2045–2054) hydrological cycle of the snow fed Oglio (≈1800 km2) Alpine watershed in Northern Italy. A Stochastic Space Random Cascade (SSRC) approach is used to downscale future precipitation from three general circulation models, GCMs (PCM, CCSM3, and HadCM3) available within the IPCC's data base and chosen for this purpose based upon previous studies. We then downscale temperature output from the GCMs to obtain temperature fields for the area. We also consider a projected scenario based upon trends locally observed in former studies, LOC scenario. Then, we feed the downscaled fields to a minimal hydrological model to build future hydrological scenarios. We provide projected flow duration curves and selected flow descriptors, giving indication of expected modified (against control run for 1990–1999) regime of low flows and droughts and flood hazard, and thus evaluate modified peak floods regime through indexed flood. We then assess the degree of uncertainty, or spread, of the projected water resources scenarios by feeding the hydrological model with ensembles projections consistent with our deterministic (GCMs + LOC) scenarios, and we evaluate the significance of the projected flow variables against those observed in the control run. The climate scenarios from the adopted GCMs differ greatly from one another with respect to projected precipitation amount and temperature regimes, and so do the projected hydrological scenarios. A relatively good agreement is found upon prospective shrinkage and shorter duration of the seasonal snow cover due to increased temperature patterns, and upon prospective increase of hydrological losses, i.e. evapotranspiration, for the same reason. However, precipitation patterns are less consistent, because HadCM3 and PCM models project noticeably increased precipitation for 2045–2054, whereas CCSM3 provides decreased precipitation patterns therein. The LOC scenario instead displays unchanged precipitation. The ensemble simulations indicate that several projected flow variables under the considered scenarios are significantly different from their control run counterparts, and also that snow cover seems to significantly decrease in duration and depth. The proposed hydrological scenarios eventually provide a what-if analysis, giving a broad view of the possible expected impacts of climate change within the Italian Alps, necessary to trigger the discussion about future adaptation strategies

Volcano monitoring from space using high-cadence planet CubeSat images applied to Fuego Volcano, Guatemala

Fuego volcano (Guatemala) is one of the most active and hazardous volcanoes in the world. Its persistent activity generates lava flows, pyroclastic density currents (PDCs), and lahars that threaten the surrounding areas and produce frequent morphological change. Fuego’s eruption deposits are often rapidly eroded or remobilized by heavy rains and its constant activity and inaccessible terrain makes ground-based assessment of recent eruptive deposits very challenging. Earth-orbiting satellites can provide unique observations of volcanoes during eruptive activity, when ground-based techniques may be too hazardous, and also during inter-eruptive phases, but have typically been hindered by relatively low spatial and temporal resolution. Here, we use a new source of Earth observation data for volcano monitoring: high resolution (~3 m pixel size) images acquired from a constellation of over 150 CubeSats (‘Doves’) operated by Planet Labs Inc. The Planet Labs constellation provides high spatial resolution at high cadence (\u3c1–72 h), permitting space-based tracking of volcanic activity with unprecedented detail. We show how PlanetScope images collected before, during, and after an eruption can be applied for mapping ash clouds, PDCs, lava flows, or the analysis of morphological change. We assess the utility of the PlanetScope data as a tool for volcano monitoring and rapid deposit mapping that could assist volcanic hazard mitigation efforts in Guatemala and other active volcanic regions