Vaccine candidates for dengue virus type 1 (DEN1) generated by replacement of the structural genes of rDEN4 and rDEN4Δ30 with those of DEN1

BACKGROUND: Antigenic chimeric viruses have previously been generated in which the structural genes of recombinant dengue virus type 4 (rDEN4) have been replaced with those derived from DEN2 or DEN3. Two vaccine candidates were identified, rDEN2/4Δ30(ME) and rDEN3/4Δ30(ME), which contain the membrane (M) precursor and envelope (E) genes of DEN2 and DEN3, respectively, and a 30 nucleotide deletion (Δ30) in the 3' untranslated region of the DEN4 backbone. Based on the promising preclinical phenotypes of these viruses and the safety and immunogenicity of rDEN2/4Δ30(ME) in humans, we now describe the generation of a panel of four antigenic chimeric DEN4 viruses using either the capsid (C), M, and E (CME) or ME structural genes of DEN1 Puerto Rico/94 strain. RESULTS: Four antigenic chimeric viruses were generated and found to replicate efficiently in Vero cells: rDEN1/4(CME), rDEN1/4Δ30(CME), rDEN1/4(ME), and rDEN1/4Δ30(ME). With the exception of rDEN1/4(ME), each chimeric virus was significantly attenuated in a SCID-HuH-7 mouse xenograft model with a 25-fold or greater reduction in replication compared to wild type DEN1. In rhesus monkeys, only chimeric viruses with the Δ30 mutation appeared to be attenuated as measured by duration and magnitude of viremia. rDEN1/4Δ30(CME) appeared over-attenuated since it failed to induce detectable neutralizing antibody and did not confer protection from wild type DEN1 challenge. In contrast, rDEN1/4Δ30(ME) induced 66% seroconversion and protection from DEN1 challenge. Presence of the Δ30 mutation conferred a significant restriction in mosquito infectivity upon rDEN1/4Δ30(ME) which was shown to be non-infectious for Aedes aegypti fed an infectious bloodmeal. CONCLUSION: The attenuation phenotype in SCID-HuH-7 mice, rhesus monkeys, and mosquitoes and the protective immunity observed in rhesus monkeys suggest that rDEN1/4Δ30(ME) should be considered for evaluation in a clinical trial

A decade's overview of Io's volcanic activity

Over the past decade some aspects of Io's volcanic activity have changed greatly, while others have essentially remained constant. This contrast has emerged from our study of multi-wavelength, infrared, observations of Io's thermal emission. From 1983 to 1992 we observed the disk integrated flux density of Io from the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. Our spectral coverage allows us to separate out the emission components due to volcanic thermal anomalies which are warmer than the background emission caused by solar heating. Our temporal coverage allows us to resolve individual eruptions and also to obtain the disk-integrated flux density as a function of longitude (or, equivalently, orbital phase angle). Characteristics that persisted over the decade involve Loki's location and intensity of emission, the leading hemisphere emission, and the average heat flow. The variable aspects of Io over the decade include Loki's hotter area(s) and the outbursts in the leading hemisphere

Addressing food insecurity in Papua New Guinea through food safety and sago cropping

Papua New Guinea (PNG) is known to have a large resource base of sago with over 1 million ha, as well as a high number of germplasm types of the Metroxylon species. The country’s food security status is very low and is primarily dependent on subsistence fresh garden produce as practiced by 85% of the population who are rural dwellers. Postharvest losses can be as high as 40% with little to no postharvest technology nor processing of foods done. Sago provides well for food security and sustains life in rural communities during disasters such as droughts, floods, and cyclones. The dilemma of sago being an underutilized crop in PNG is exacerbated by the introduction of new food crops, cash crops, and limited accessibility to cash to purchase other foods. Over the last 50 years, sago consumption has diminished as one of the major traditional food staples, from 16% to less than 10%. Neglect of sago is further due to food safety concerns about traditionally processed sago, in particular, the risk from sago hemolytic disease (SHD). For over30 years, SHD has been a food safety issue since it was first reported in 1973.Investigations on SHD highlight the serious need to improve on the hygiene and sanitation of the traditional postharvest processing and storage methods of sago starch in PNG. A set of hazard analysis and critical control point (HACCP) protocols has been developed for traditional processing of sago as a food safety measure to improve food safety for food security. While commercial cultivation is nonexistent, there is increased planting of the larger hapaxanthic, non-soboliferous sagospecies, Metroxylon salomonense Becc., in some nontraditional sago-consuming areas as a low-cost raw material source for roof thatching and other building materials. It is however a wasted opportunity for food security in these areas as the starch from the palm is not utilized. Current work in these areas promotes sago as a potential food source that can be harvested or processed into flour. This is to improve the food security status in areas of high population density, like island communities where land is scarce

Vaccine candidates derived from a novel infectious cDNA clone of an American genotype dengue virus type 2

BACKGROUND: A dengue virus type 2 (DEN-2 Tonga/74) isolated from a 1974 epidemic was characterized by mild illness and belongs to the American genotype of DEN-2 viruses. To prepare a vaccine candidate, a previously described 30 nucleotide deletion (Δ30) in the 3' untranslated region of DEN-4 has been engineered into the DEN-2 isolate. METHODS: A full-length cDNA clone was generated from the DEN-2 virus and used to produce recombinant DEN-2 (rDEN-2) and rDEN2Δ30. Viruses were evaluated for replication in SCID mice transplanted with human hepatoma cells (SCID-HuH-7 mice), in mosquitoes, and in rhesus monkeys. Neutralizing antibody induction and protective efficacy were also assessed in rhesus monkeys. RESULTS: The rDEN2Δ30 virus was ten-fold reduced in replication in SCID-HuH-7 mice when compared to the parent virus. The rDEN-2 viruses were not infectious for Aedes mosquitoes, but both readily infected Toxorynchites mosquitoes. In rhesus monkeys, rDEN2Δ30 appeared to be slightly attenuated when compared to the parent virus as measured by duration and peak of viremia and neutralizing antibody induction. A derivative of rDEN2Δ30, designated rDEN2Δ30-4995, was generated by incorporation of a point mutation previously identified in the NS3 gene of DEN-4 and was found to be more attenuated than rDEN2Δ30 in SCID-HuH-7 mice. CONCLUSIONS: The rDEN2Δ30 and rDEN2Δ30-4995 viruses can be considered for evaluation in humans and for inclusion in a tetravalent dengue vaccine

A trade-off in replication in mosquito versus mammalian systems conferred by a point mutation in the NS4B protein of dengue virus type 4

AbstractAn acceptable live-attenuated dengue virus vaccine candidate should have low potential for transmission by mosquitoes. We have identified and characterized a mutation in dengue virus type 4 (DEN4) that decreases the ability of the virus to infect mosquitoes. A panel of 1248 mutagenized virus clones generated previously by chemical mutagenesis was screened for decreased replication in mosquito C6/36 cells but efficient replication in simian Vero cells. One virus met these criteria and contained a single coding mutation: a C-to-U mutation at nucleotide 7129 resulting in a Pro-to-Leu change in amino acid 101 of the nonstructural 4B gene (NS4B P101L). This mutation results in decreased replication in C6/36 cells relative to wild-type DEN4, decreased infectivity for mosquitoes, enhanced replication in Vero and human HuH-7 cells, and enhanced replication in SCID mice implanted with HuH-7 cells (SCID-HuH-7 mice). A recombinant DEN4 virus (rDEN4) bearing this mutation exhibited the same set of phenotypes. Addition of the NS4B P101L mutation to rDEN4 bearing a 30 nucleotide deletion (Δ30) decreased the ability of the double-mutant virus to infect mosquitoes but increased its ability to replicate in SCID-HuH-7 mice. Although the NS4B P101L mutation decreases infectivity of DEN4 for mosquitoes, its ability to enhance replication in SCID-HuH-7 mice suggests that it might not be advantageous to include this specific mutation in an rDEN4 vaccine. The opposing effects of the NS4B P101L mutation in mosquito and vertebrate systems suggest that the NS4B protein is involved in maintaining the balance between efficient replication in the mosquito vector and the human host

Constraining the Texture and Composition of Pore-Filling Cements at Gale Crater, Mars

The Mars Science Laboratory (MSL) rover Curiosity has encountered a wide variety of sedimentary rocks deposited in fluvio-lacuestrine sequences at the base of Gale Crater. The presence of sedimentary rocks requires that initial sediments underwent diagenesis and were lithified. Lithification involves sediment compaction, cementation, and re-crystallization (or authigenic) processes. Analysis of the texture and composition of the cement can reveal the environmental conditions when the cements were deposited, enabling better understanding of early environments present within Gale Crater. The first step in lithification is sediment compaction. The Gale crater sediments do not show evidence for extensive compaction prior to cementation; the Sheepbed mudstone in Yellowknife Bay (YKB) has preserved void spaces ("hollow nodules"), indicating that sediments were cemented around the hollow prior to compaction, and conglomerates show imbrication, indicating minimal grain reorganization prior to lithification. Furthermore, assuming the maximum burial depth of these sediments is equivalent to the depth of Gale Crater, the sediments were never under more than 1 kb of pressure, and assuming a 15 C/km thermal gradient in the late Noachian, the maximum temperature of diagenesis would have been approximately 75 C. This is comparable to shallow burial diagenetic conditions on Earth. The cementation and recrystallization components of lithification are closely intertwined. Cementation describes the precipitation of minerals between grains from pore fluids, and recrystallization (or authigenesis) is when the original sedimentary mineral grains are altered into secondary minerals. The presence of authigenic smectites and magnetite in the YKB formation suggests that some recrystallization has taken place. The relatively high percentage of XRD-amorphous material (25-40%) detected by CheMin suggests that this recrystallization may be limited in scope, and therefore may not contribute significantly to the cementing material. However, relatively persistent amorphous components could exist in the Martian environment (e.g. amorphous MgSO4), so recrystallization, including loss of crystallinity, cannot yet be excluded as a method of cementation. In order to describe the rock cementation, both the rock textures and their composition must be considered. Here, we attempt to summarize the current understanding of the textural and compositional aspects of the cement across the rocks analyzed by Curiosity to this point

Age-dependent alteration of TGF-β signalling in osteoarthritis

Osteoarthritis (OA) is a disease of articular cartilage, with aging as the main risk factor. In OA, changes in chondrocytes lead to the autolytic destruction of cartilage. Transforming growth factor-β has recently been demonstrated to signal not only via activin receptor-like kinase 5 (ALK5)-induced Smad2/3 phosphorylation, but also via ALK1-induced Smad1/5/8 phosphorylation in articular cartilage. In aging cartilage and experimental OA, the ratio ALK1/ALK5 has been found to be increased, and the expression of ALK1 is correlated with matrix metalloproteinase-13 expression. The age-dependent shift towards Smad1/5/8 signalling might trigger the differentiation of articular chondrocytes with an autolytic phenotype

The 28 November 2020 Landslide, Tsunami, and Outburst Flood – A Hazard Cascade Associated With Rapid Deglaciation at Elliot Creek, British Columbia, Canada

We describe and model the evolution of a recent landslide, tsunami, outburst flood, and sediment plume in the southern Coast Mountains, British Columbia, Canada. On November 28, 2020, about 18 million m3 of rock descended 1,000 m from a steep valley wall and traveled across the toe of a glacier before entering a 0.6 km2 glacier lake and producing >100-m high run-up. Water overtopped the lake outlet and scoured a 10-km long channel before depositing debris on a 2-km2 fan below the lake outlet. Floodwater, organic debris, and fine sediment entered a fjord where it produced a 60+km long sediment plume and altered turbidity, water temperature, and water chemistry for weeks. The outburst flood destroyed forest and salmon spawning habitat. Physically based models of the landslide, tsunami, and flood provide real-time simulations of the event and can improve understanding of similar hazard cascades and the risk they pose

Difficulties associated with outpatient management of drug abusers by general practitioners. A cross-sectional survey of general practitioners with and without methadone patients in Switzerland

BACKGROUND: In Switzerland, general practitioners (GPs) manage most of the patients receiving methadone maintenance treatment (MMT). METHODS: Using a cross-sectional postal survey of GPs who treat MMT patients and GPs who do not, we studied the difficulties encountered in the out-patient management of drug-addicted patients. We sent a questionnaire to every GP with MMT patients (556) in the French-speaking part of Switzerland (1,757,000 inhabitants). We sent another shorter questionnaire to primary care physicians without MMT patients living in the Swiss Canton of Vaud. RESULTS: The response rate was 63.3%. The highest methadone dose given by GPs to MMT patients averaged 120.4 mg/day. When asked about help they would like to be given, GPs with MMT patients primarily mentioned the importance of receiving adequate fees for the care they provide. Secondly, they mentioned the importance of better training, better knowledge of psychiatric pathologies, and discussion groups on practical cases. GPs without MMT patients refuse to treat these patients mostly for emotional and relational reasons. CONCLUSION: GPs encounter financial, relational and emotional difficulties with MMT patients. They desire better fees for services and better training