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Journal articles on the topic "Mount Isa Province"
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Simpson, Janelle, and Graham Heinson. "Tectonic framework of the southern Mount Isa Province." ASEG Extended Abstracts 2018, no. 1 (December 2018): 1–4. http://dx.doi.org/10.1071/aseg2018abm3_3g.
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Williams, P. J. "Metallogeny of the McArthur River-Mount Isa-Cloncurry minerals province; preface." Economic Geology 93, no. 8 (December 1, 1998): 1119–0. http://dx.doi.org/10.2113/gsecongeo.93.8.1119.
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Williams, Patrick J. "An introduction to the metallogeny of the McArthur River-Mount Isa-Cloncurry minerals province." Economic Geology 93, no. 8 (December 1, 1998): 1120–31. http://dx.doi.org/10.2113/gsecongeo.93.8.1120.
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Beard, Charles D., Nicholas Arndt, Richard Lynch, and Jamin Cristall. "Cover Mapping with Passive Seismics at the Boulia Prospect, Mount Isa Province, Queensland, Australia." First Break 40, no. 6 (June 1, 2022): 89–96. http://dx.doi.org/10.3997/1365-2397.fb2022052.
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Walter, M. R., I. N. Krylov, and M. D. Muir. "Stromatolites from Middle and Late Proterozoic sequences in the McArthur and Georgina Basins and the Mount Isa Province, Australia." Alcheringa: An Australasian Journal of Palaeontology 12, no. 2 (January 1988): 79–106. http://dx.doi.org/10.1080/03115518808618998.
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Wecker, H. R. B., V. Ziolkowski, and G. D. Powis. "NEW GAS DISCOVERIES IN THE NORTHERN COOPER BASIN." APPEA Journal 36, no. 1 (1996): 104. http://dx.doi.org/10.1071/aj95006.
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Over the last two decades, minimal gas exploration was undertaken in the northeastern Cooper Basin. It was viewed the area held negligible gas potential due to the perceived absence of conventional anticlinal traps and the marginal reservoir quality of the Permian sandstones.With the award of permit ATP 549P to Mount Isa Mines Limited in mid-1993, available seismic and well data were reviewed to highlight potential fault-controlled traps in the region and to define areas likely to contain more favourable reservoir sandstones. A vibroseis seismic survey provided the initial prospects and leads inventory upon which the 1994 drilling program was based. Four prospects were tested resulting in three gas discoveries.Based on these encouraging results, an additional phase of seismic acquisition was completed to increase the prospect inventory. Thereafter, a five well program was undertaken. Whilst the two appraisal wells were successful, three wildcat wells failed due to ineffective trapping.A completion and testing program has been initiated to further evaluate the field discoveries.From an exploration viewpoint, the recognition of a consistently productive sandstone in the basal Toolachee Formation within a broad fairway across the eastern ATP 549P permit block was a significant result which has important implications for future activities. Within the fairway, gas flows varying from 0.4 MMcfd up to 6.0 MMcfd were measured on openhole tests. In addition, substantial gas volumes in low permeability sandstones within the Patchawarra Formation have been defined.These discoveries, coupled with the number of prospects and leads and the proposed gas pipeline to Mount Isa and to southeast Queensland markets, provide strong impetus to the continued evaluation of this northern extension of the Cooper Basin gas province.
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Rieger, Philip, Joseph M. Magnall, Sarah A. Gleeson, Richard Lilly, Alexander Rocholl, and Christof Kusebauch. "Sulfur Isotope Constraints on the Conditions of Pyrite Formation in the Paleoproterozoic Urquhart Shale Formation and George Fisher Zn-Pb-Ag Deposit, Northern Australia." Economic Geology 115, no. 5 (August 1, 2020): 1003–20. http://dx.doi.org/10.5382/econgeo.4726.
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Abstract The Carpentaria province (McArthur basin and Mount Isa inlier) in northern Australia is one of the most important districts for clastic-dominated (CD-type) massive sulfide deposits. The George Fisher Zn-Pb-Ag deposit, located in this province, is hosted by the carbonaceous Urquhart Shale Formation (ca. 1654 Ma) in a region that has an active history of metamorphism and tectonism. In this study, paragenetically constrained pyrite in samples from the George Fisher deposit and unmineralized Urquhart Shale have been analyzed in situ using secondary ion mass spectrometry (SIMS) of sulfur isotopes (δ34S values). Samples were taken from four drill cores through the main orebodies at George Fisher and one drill core through correlative, unmineralized Urquhart Shale (Shovel Flats area). Five generations of pyrite were identified at George Fisher and record a protracted history of sulfate reduction under diagenetic and subsequent hydrothermal conditions: (1) fine-grained, subhedral-spheroidal pyrite (Py-0), (2) coarse-grained, anhedral pyrite (Py-1) associated with ore-stage 1 sphalerite and galena, (3) coarse-grained, euhedral pyrite (Py-2) associated with ore-stage 2 sphalerite, galena, and pyrrhotite, (4) massive subhedral to euhedral pyrite (Py-3) associated with ore-stage 3 chalcopyrite, pyrrhotite, galena, and sphalerite, and (5) coarse-grained euhedral pyrite (Py-euh), which occurs only in unmineralized rocks. In the unmineralized Shovel Flats drill core, only Py-0 and Py-euh are present. Whereas pre-ore pyrite (Py-0) preserves negative δ34S values (–8.1 to 11.8‰), the ore-stage pyrites (Py-1, Py-2, and Py-3) have higher δ34S values (7.8–33.3, 1.9–12.7, and 23.4–28.2‰, respectively). The highest δ34S values (7.2–33.9‰) are preserved in Py-euh. In combination with petrographic observations, the δ34S values of pyrite provide evidence of three different processes responsible for the reduction of sulfate at George Fisher. Reduced sulfur in fine-grained pyrite (Py-0) formed via microbial sulfate reduction (MSR) under open-system conditions prior to the first generation of hydrothermal pyrite (Py-1) in ore-stage 1, which most likely formed via thermochemical sulfate reduction (TSR). During deformation, previously formed sulfide phases were then recycled and replaced during a second hydrothermal event (ore-stage 2), resulting in intermediate sulfur isotope values. Another syndeformational hydrothermal Cu event, involving a sulfate-bearing fluid, formed ore-stage 3 via TSR. This study demonstrates that the fine-grained pyrite formed pre-ore under conditions open to sulfate and outlines the role of multiple stages of sulfide formation in producing high-grade Zn-Pb-Ag orebodies in the Mount Isa inlier.
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Page, R. W., C. H. H. Conor, B. P. J. Stevens, G. M. Gibson, W. V. Preiss, and P. N. Southgate. "Correlation of Olary and Broken Hill Domains, Curnamona Province: Possible Relationship to Mount Isa and Other North Australian Pb-Zn-Ag-Bearing Successions." Economic Geology 100, no. 4 (June 1, 2005): 663–76. http://dx.doi.org/10.2113/100.4.663.
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Gibson, G. M., A. J. Meixner, I. W. Withnall, R. J. Korsch, L. J. Hutton, L. E. A. Jones, J. Holzschuh, R. D. Costelloe, P. A. Henson, and E. Saygin. "Basin architecture and evolution in the Mount Isa mineral province, northern Australia: Constraints from deep seismic reflection profiling and implications for ore genesis." Ore Geology Reviews 76 (July 2016): 414–41. http://dx.doi.org/10.1016/j.oregeorev.2015.07.013.
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Korsch, Russell, Heike Struckmeyer, Alison Kirkby, Laurie Hutton, Lidena Carr, Kinta Hoffmann, Richard Chopping, et al. "Energy potential of the Millungera Basin: a newly discovered basin in north Queensland." APPEA Journal 51, no. 1 (2011): 295. http://dx.doi.org/10.1071/aj10020.
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Deep seismic reflection surveys in north Queensland that were collected in 2006 and 2007 discovered a previously unknown sedimentary basin, now named the Millungera Basin, which is completely covered by a thin succession of sediments of the Jurassic–Cretaceous, Eromanga-Carpentaria Basin. Interpretation of regional aeromagnetic data suggests that the basin could have areal dimensions of up to 280 km by 95 km. Apart from regional geophysical data, virtually no confirmed geological information exists on the basin. To complement the seismic data, new magnetotelluric data have been acquired on several lines across the basin. An angular unconformity between the Eromanga and Millungera basins indicates that the upper part of the Millungera Basin was eroded prior to deposition of the Eromanga-Carpentaria Basin. Both the western and eastern margins of the Millungera Basin are truncated by thrust faults, with well-developed hangingwall anticlines occurring above the thrusts at the eastern margin. The basin thickens slightly to the east, to a maximum preserved subsurface depth of ˜3,370 m. Using sequence stratigraphic principles, three discrete sequences have been mapped. The geometry of the stratigraphic sequences, the post-depositional thrust margins, and the erosional unconformity at the top of the succession all indicate that the original succession across much of the basin was thicker–by up to at least 1,500 m–than preserved today. The age of the Millungera Basin is unknown, but petroleum systems modelling has been carried out using two scenarios, that is, that the sediment fill is equivalent in age to (1) the Neoproterozoic-Devonian Georgina Basin, or (2) the Permian–Triassic Lovelle Depression of the Galilee Basin. Using the Georgina Basin analogue, potential Cambrian source rocks are likely to be mature over most of the Millungera Basin, with significant generation and expulsion of hydrocarbons occurring in two phases, in response to Ordovician and Cretaceous sediment loading. For the Galilee Basin analogue, potential Permian source rocks are likely to be oil mature in the central Millungera Basin, but immature on the basin margins. Significant oil generation and expulsion probably occurred during the Triassic, in response to late Permian to Early Triassic sediment loading. Based on the seismic and potential field data, several granites are interpreted to occur immediately below the Millungera Basin, raising the possibility of hot rock geothermal plays. Depending on its composition, the Millungera Basin could provide a thermal blanket to trap any heat which is generated. 3D inversion of potential field data suggests that the inferred granites range from being magnetic to nonmagnetic, and felsic (less dense) to more mafic. They may be part of the Williams Supersuite, which is enriched in uranium, thorium and potassium, and exposed just to the west, in the Mount Isa Province. 3D gravity modelling suggests that the inferred granites have a possible maximum thickness of up to 5.5 km. Therefore, if granites with the composition of the Williams Supersuite occur beneath the Millungera Basin, in the volumes indicated by gravity inversions, then, based on the forward temperature modelling, there is a good probability that the basin is prospective for geothermal energy.
Dissertations / Theses on the topic "Mount Isa Province"
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Simpson, Janelle Maree. "Understanding interpretation limitations due to MT inversion variability: examples from the Mount Isa Province, Queensland, Australia." Thesis, 2019. http://hdl.handle.net/2440/122614.
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Exploration undercover presents a significant challenge and relies heavily on the effective interpretation of geophysical data. Magnetotelluric (MT) surveying is an ideal method for characterising these covered terranes because it provides resolution from the shallow cover into the deep earth. Undercover terranes often lack constraining information, creating a significant impediment for translating geophysical features into geological interpretations. This thesis presents advances for understanding MT inversion uncertainty to produce better geological interpretations in data-poor areas. The project area is along strike from major Pb-Zn-Ag deposits at Mount Isa and George Fischer, and includes the location of a proposed suture between the Mount Isa Province and the North Australian Craton. The structure is interpreted from potential field data by previous workers but is not observable in outcrop. The prospective Proterozoic packages are concealed beneath 200-1200 m of Phanerozoic cover and consequently exploration success in this area has been very poor. The project dataset contains 1600 audiomagnetotelluric (AMT; 10-4 to 100 seconds) and broadband MT (BBMT; 10-2 to 103 seconds) sites; with approximate survey dimensions of 90 km north-south with line spacing of 5 km, and 150 km east-west with inter-site spacing of 2 km. The project area has scarce geological and geophysical information, and there is an inadequate understanding of the macro-scale geological structure. Three studies were undertaken with the aim of creating a new geological interpretation for the area. These studies were based on quantifying inversion variability and integration of information during interpretation. One study presents a workflow to objectively assess the variability of models produced during 3D magnetotelluric inversion. The workflow uses a sequential inversion methodology to examine model variability while minimising the computational demand of 3D inversion. The results highlight the high degree of variability permissible in 3D MT inversion models and reinforce the clear impact inversion parameterisation has on the inversion models. Our method allows objective differentiation between well- and poorly-constrained features. The second study integrates the results of 3D magnetotelluric inversion and variability analysis from the previous study, with deep crustal seismic and potential field data to refine our understanding of the southern Mount Isa Province. A new crustal-scale west-dipping feature is identified that is adjacent to a major change in crustal thickness and associated with a major change in crustal resistivity (that extends at least 400 km to the north). There is additionally a conductor located on or just above the interface and significant changes in the potential field response corresponding to both upper crustal and lower crustal depths. The structure is spatially associated with a low-resistivity feature (interpreted to be due to fluid movement or alteration), extends into the shallow crust and represents a possible exploration target. The third study is focused on resolving the depth to basement and basin morphology of the Neoproterozoic-Mesozoic cover basins in the project area. Resolving the depth to basement from MT data is inherently difficult due to the data’s insensitivity to the top of a resistive package (such as crystalline basement rocks). We used a combination of 1D probabilistic inversion, 2D deterministic inversion and synthetic modelling of downhole resistivity data to produce the final interpretation. The interpretation includes the base of the Eromanga Basin, an intra-Georgina Basin low-resistivity layer and depth to basement, all of which have associated error estimates. Understanding variability in geophysical inversion is integral to the construction of a well-supported geological interpretation. This is especially true for areas where constraining information is limited or absent. We demonstrate that an understanding of data resolution and model uncertainty enables interpretation of new, worthwhile geological information from MT inversion even in data-poor greenfield terranes. Our new interpretation de-risks mineral exploration and provide new insights into crustal structures important for exploration targeting.Thesis (Ph.D.) -- University of Adelaide, School of Physical Sciences, 2019
Reports on the topic "Mount Isa Province"
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Anderson, J. R., C. J. Lewis, A. J. M. Jarrett, L. K. Carr, P. Henson, C. J. Carson, C. Southby, and T. J. Munson. New SHRIMP U-Pb zircon ages from the South Nicholson Basin, Mount Isa Province and Georgina Basin, Northern Territory and Queensland: July 2017-June 2018. Geoscience Australia, 2019. http://dx.doi.org/10.11636/record.2019.010.
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Liu, X., Z. Chen, and S. E. Grasby. Using shallow temperature measurements to evaluate thermal flux anomalies in the southern Mount Meager volcanic area, British Columbia, Canada. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330009.
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Geothermal is a clean and renewable energy resource. However, locating where elevated thermal gradient anomalies exist is a significant challenge when trying to assess potential resource volumes during early exploration of a prospective geothermal area. In this study, we deployed 22 temperature probes in the shallow subsurface along the south flank of the Mount Meager volcanic complex, to measure the transient temperature variation from September 2020 to August 2021. In our data analysis, a novel approach was developed to estimate the near-surface thermal distribution, and a workflow and code with python language have been completed for the thermal data pre-processing and analysis. The long-term temperature variation at different depths can be estimated by modelling, so that the relative difference of deducing deeper geothermal gradient anomalies can be assessed. Our proposed inversion and simulation methods were applied to calculating the temperature variation at 2.0 meters depth. The results identified a preferred high thermal flux anomalous zone in the south Mount Meager area. By combining with previous studies, the direct analysis and estimation of anomalous thermal fields based on the collected temperature data can provide a significant reference for interpretation of the regional thermal gradient variation.
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Chen, Z., S. E. Grasby, C. Deblonde, and X. Liu. AI-enabled remote sensing data interpretation for geothermal resource evaluation as applied to the Mount Meager geothermal prospective area. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330008.
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The objective of this study is to search for features and indicators from the identified geothermal resource sweet spot in the south Mount Meager area that are applicable to other volcanic complexes in the Garibaldi Volcanic Belt. A Landsat 8 multi-spectral band dataset, for a total of 57 images ranging from visible through infrared to thermal infrared frequency channels and covering different years and seasons, were selected. Specific features that are indicative of high geothermal heat flux, fractured permeable zones, and groundwater circulation, the three key elements in exploring for geothermal resource, were extracted. The thermal infrared images from different seasons show occurrence of high temperature anomalies and their association with volcanic and intrusive bodies, and reveal the variation in location and intensity of the anomalies with time over four seasons, allowing inference of specific heat transform mechanisms. Automatically extracted linear features using AI/ML algorithms developed for computer vision from various frequency bands show various linear segment groups that are likely surface expression associated with local volcanic activities, regional deformation and slope failure. In conjunction with regional structural models and field observations, the anomalies and features from remotely sensed images were interpreted to provide new insights for improving our understanding of the Mount Meager geothermal system and its characteristics. After validation, the methods developed and indicators identified in this study can be applied to other volcanic complexes in the Garibaldi, or other volcanic belts for geothermal resource reconnaissance.
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Hurlow, Hugh A., Paul C. Inkenbrandt, and Trevor H. Schlossnagle. Hydrogeology, Groundwater Chemistry, and Water Budget of Juab Valley, Eastern Juab County, Utah. Utah Geological Survey, October 2022. http://dx.doi.org/10.34191/ss-170.
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Juab Valley is a north-south-trending basin in the eastern Basin and Range Province. Juab Valley is bounded on the east by the Wasatch normal fault and the Wasatch Range and San Pitch Mountains, bounded on the west by Long Ridge and the West Hills. Juab Valley is at the southern end of Utah’s Wasatch Front, an area of projected rapid population growth and increased groundwater use. East-west-trending surface-water, groundwater, and water-rights boundaries approximately coincide along the valley’s geographic midline at Levan Ridge, an east-west trending watershed divide that separates the north and south parts of Juab Valley. The basin includes, from north to south, the towns of Mona, Nephi, and Levan, which support local agricultural and light-industrial businesses. Groundwater use is essential to Juab Valley’s economy. The Juab Valley study area consists of surficial unconsolidated basin-fill deposits at lower elevations and various bedrock units surrounding and underlying the basin-fill deposits. Quaternary-Tertiary basin-fill deposits form Juab Valley’s primary aquifer. Tertiary volcanic rocks underlie some of the basinfill deposits and form the central part of Long Ridge on the northwest side of the valley. Paleozoic carbonate rocks that crop out in the Mount Nebo area of the Wasatch Range, which receives the greatest average annual precipitation in the study area, likely accommodate infiltration of snowmelt and subsurface groundwater flow to the basin-fill aquifer. The Jurassic Arapien Formation also crops out in the Wasatch Range and San Pitch Mountains, and dissolution of gypsum and halite in the formation and sediments derived from it increases the sulfate, sodium, and total-dissolved-solids concentrations of surface water and groundwater. We grouped the stratigraphy of the Juab Valley study area into 19 hydrostratigraphic units based on known and interpreted hydraulic properties.
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Hodul, M., H. P. White, and A. Knudby. A report on water quality monitoring in Quesnel Lake, British Columbia, subsequent to the Mount Polley tailings dam spill, using optical satellite imagery. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330556.
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In the early morning on the 4th of August 2014, a tailings dam near Quesnel, BC burst, spilling approximately 25 million m3 of runoff containing heavy metal elements into nearby Quesnel Lake (Byrne et al. 2018). The runoff slurry, which included lead, arsenic, selenium, and vanadium spilled through Hazeltine Creek, scouring its banks and picking up till and forest cover on the way, and ultimately ended up in Quesnel Lake, whose water level rose by 1.5 m as a result. While the introduction of heavy metals into Quesnel Lake was of environmental concern, the additional till and forest cover scoured from the banks of Hazeltine Creek added to the lake has also been of concern to salmon spawning grounds. Immediate repercussions of the spill involved the damage of sensitive environments along the banks and on the lake bed, the closing of the seasonal salmon fishery in the lake, and a change in the microbial composition of the lake bed (Hatam et al. 2019). In addition, there appears to be a seasonal resuspension of the tailings sediment due to thermal cycling of the water and surface winds (Hamilton et al. 2020). While the water quality of Quesnel Lake continues to be monitored for the tailings sediments, primarily by members at the Quesnel River Research Centre, the sample-and-test methods of water quality testing used, while highly accurate, are expensive to undertake, and not spatially exhaustive. The use of remote sensing techniques, though not as accurate as lab testing, allows for the relatively fast creation of expansive water quality maps using sensors mounted on boats, planes, and satellites (Ritchie et al. 2003). The most common method for the remote sensing of surface water quality is through the use of a physics-based semianalytical model which simulates light passing through a water column with a given set of Inherent Optical Properties (IOPs), developed by Lee et al. (1998) and commonly referred to as a Radiative Transfer Model (RTM). The RTM forward-models a wide range of water-leaving spectral signatures based on IOPs determined by a mix of water constituents, including natural materials and pollutants. Remote sensing imagery is then used to invert the model by finding the modelled water spectrum which most closely resembles that seen in the imagery (Brando et al 2009). This project set out to develop an RTM water quality model to monitor the water quality in Quesnel Lake, allowing for the entire surface of the lake to be mapped at once, in an effort to easily determine the timing and extent of resuspension events, as well as potentially investigate greening events reported by locals. The project intended to use a combination of multispectral imagery (Landsat-8 and Sentinel-2), as well as hyperspectral imagery (DESIS), combined with field calibration/validation of the resulting models. The project began in the Autumn before the COVID pandemic, with plans to undertake a comprehensive fieldwork campaign to gather model calibration data in the summer of 2020. Since a province-wide travel shutdown and social distancing procedures made it difficult to carry out water quality surveying in a small boat, an insufficient amount of fieldwork was conducted to suit the needs of the project. Thus, the project has been put on hold, and the primary researcher has moved to a different project. This document stands as a report on all of the work conducted up to April 2021, intended largely as an instructional document for researchers who may wish to continue the work once fieldwork may freely and safely resume. This research was undertaken at the University of Ottawa, with supporting funding provided by the Earth Observations for Cumulative Effects (EO4CE) Program Work Package 10b: Site Monitoring and Remediation, Canada Centre for Remote Sensing, through the Natural Resources Canada Research Affiliate Program (RAP).
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Chejanovsky, Nor, and Bruce A. Webb. Potentiation of pest control by insect immunosuppression. United States Department of Agriculture, July 2004. http://dx.doi.org/10.32747/2004.7587236.bard.
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Our original aims were to elucidate the mechanisms through which the immunosuppressive insect virus, the Campoletis sonorensis polydnavirus (CsV) promotes replication of a well-characterized pathogenic virus, the Autographa californica multiple nucleopolyhedrovirus (AcMNPV) in hosts that are mildly or non-permissive to virus replication. According to the BARD panels criticism we modified our short-term goals (see below). Thus, in this feasibility study (one-year funding) we aimed to show that: 1. S. littoralis larvae mount an immune response against a baculovirus infection. 2. Immunosuppression of an insect pest improves the ability of a viral pathogen (a baculovirus) to infect the pest. 3. S. littoralis cells constitute an efficient tool to study some aspects of the anti- viral immune response. We achieved the above objectives by: 1. Finding melanized viral foci upon following the baculoviral infection in S . littoralis larvae infected with a polyhedra - positive AcMNPV recombinant that expressed the GFP gene under the control of the Drosophila heat shock promoter. 2. Studying the effect of AcMNPV-infection in S . littoralis immunosuppressed by parasitation with the Braconidae wasp Chelonus inanitus that bears the CiV polydna virus, that resulted in higher susceptibility of S. littoralis to AcMNPV- infection. 3. Proving that S. littoralis hemocytes resist AcMNPV -infection. 4. Defining SL2 as a granulocyte-like cell line and demonstrating that as littoralis hemocytic cell line undergoes apoptosis upon AcMNPV -infection. 5. Showing that some of the recombinant AcMNPV expressing the immuno-suppressive polydna virus CsV- vankyrin genes inhibit baculoviral-induced lysis of SL2 cells. This information paves the way to elucidate the mechanisms through which the immuno- suppressive polydna insect viruses promote replication of pathogenic baculoviruses in lepidopteran hosts that are mildly or non-permissive to virus- replication by: - Assessing the extent to which and the mechanisms whereby the immunosuppressive viruses, CiV and CsV or their genes enhance AcMNPV replication in polydnavirus- immunosuppressed H. zea and S. littoralis insects and S. littoralis cells. - Identifying CiV and CsV genes involved in the above immunosuppression (e.g. inhibiting cellular encapsulation and disrupting humoral immunity). This study will provide insight to the molecular mechanisms of viral pathogenesis and improve our understanding of insect immunity. This knowledge is of fundamental importance to controlling insect vectored diseases of humans, animals and plants and essential to developing novel means for pest control (including baculoviruses) that strategically weaken insect defenses to improve pathogen (i.e. biocontrol agent) infection and virulence.
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Chejanovsky, Nor, and Bruce A. Webb. Potentiation of Pest Control by Insect Immunosuppression. United States Department of Agriculture, January 2010. http://dx.doi.org/10.32747/2010.7592113.bard.
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The restricted host range of many baculoviruses, highly pathogenic to Lepidoptera and non-pathogenic to mammals, limits their use to single or few closely related Lepidopteran species and is an obstacle to extending their implementation for pest control. The insect immune response is a major determinant of the ability of an insect pathogen to efficiently multiply and propagate. We have developed an original model system to study the Lepidopteran antiviral immune response based on Spodoptera littoralis resistance to AcMNPV (Autographa californica multiple nucleopolyhedrovirus) infection and the fascinating immunosuppressive activity of polydnaviruses .Our aim is to elucidate the mechanisms through which the immunosuppressive insect polydnaviruses promote replication of pathogenic baculoviruses in lepidopteran hosts that are mildly or non-permissive to virus- replication. In this study we : 1- Assessed the extent to which and the mechanisms whereby the immunosuppressive Campoletis sonorensis polydnavirus (CsV) or its genes enhanced replication of a well-characterized pathogenic baculovirus AcMNPV, in polydnavirus-immunosuppressedH. zea and S. littoralis insects and S. littoralis cells, hosts that are mildly or non-permissive to AcMNPV. 2- Identified CsV genes involved in the above immunosuppression (e.g. inhibiting cellular encapsulation and disrupting humoral immunity). We showed that: 1. S. littoralis larvae mount an immune response against a baculovirus infection. 2. Immunosuppression of an insect pest improves the ability of a viral pathogen, the baculovirus AcMNPV, to infect the pest. 3. For the first time two PDV-specific genes of the vankyrin and cystein rich-motif families involved in immunosuppression of the host, namely Pvank1 and Hv1.1 respectively, enhanced the efficacy of an insect pathogen toward a semipermissive pest. 4. Pvank1 inhibits apoptosis of Spodopteran cells elucidating one functional aspect of PDVvankyrins. 5. That Pvank-1 and Hv1.1 do not show cooperative effect in S. littoralis when co-expressed during AcMNPV infection. Our results pave the way to developing novel means for pest control, including baculoviruses, that rely upon suppressing host immune systems by strategically weakening insect defenses to improve pathogen (i.e. biocontrol agent) infection and virulence. Also, we expect that the above result will help to develop systems for enhanced insect control that may ultimately help to reduce transmission of insect vectored diseases of humans, animals and plants as well as provide mechanisms for suppression of insect populations that damage crop plants by direct feeding.