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1
Gooding, R. H. "Genetic variation in arthropod vectors of disease-causing organisms: obstacles and opportunities." Clinical Microbiology Reviews 9, n.º 3 (julho de 1996): 301–20. http://dx.doi.org/10.1128/cmr.9.3.301.
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An overview of the genetic variation in arthropods that transmit pathogens to vertebrates is presented, emphasizing the genetics of vector-pathogen relationships and the biochemical genetics of vectors. Vector-pathogen interactions are reviewed briefly as a prelude to a discussion of the genetics of susceptibility and refractoriness in vectors. Susceptibility to pathogens is controlled by maternally inherited factors, sex-linked dominant alleles, and dominant and recessive autosomal genes. There is widespread interpopulation (including intercolony) and temporal variation in susceptibility to pathogens. The amount of biochemical genetic variation in vectors is similar to that found in other invertebrates. However, the amount varies widely among species, among populations within species, and temporally within populations. Biochemical genetic studies show that there is considerable genetic structuring of many vectors at the local, regional, and global levels. It is argued that genetic variation in vectors is critical in understanding vector-pathogen interactions and that genetic variation in vectors creates both obstacles to and opportunities for application of genetic techniques to the control of vectors.
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Yew, Chee-Hong Takahiro, Narmatha Gurumoorthy, Fazlina Nordin, Gee Jun Tye, Wan Safwani Wan Kamarul Zaman, Jun Jie Tan e Min Hwei Ng. "Integrase deficient lentiviral vector: prospects for safe clinical applications". PeerJ 10 (12 de agosto de 2022): e13704. http://dx.doi.org/10.7717/peerj.13704.
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HIV-1 derived lentiviral vector is an efficient transporter for delivering desired genetic materials into the targeted cells among many viral vectors. Genetic material transduced by lentiviral vector is integrated into the cell genome to introduce new functions, repair defective cell metabolism, and stimulate certain cell functions. Various measures have been administered in different generations of lentiviral vector systems to reduce the vector’s replicating capabilities. Despite numerous demonstrations of an excellent safety profile of integrative lentiviral vectors, the precautionary approach has prompted the development of integrase-deficient versions of these vectors. The generation of integrase-deficient lentiviral vectors by abrogating integrase activity in lentiviral vector systems reduces the rate of transgenes integration into host genomes. With this feature, the integrase-deficient lentiviral vector is advantageous for therapeutic implementation and widens its clinical applications. This short review delineates the biology of HIV-1-erived lentiviral vector, generation of integrase-deficient lentiviral vector, recent studies involving integrase-deficient lentiviral vectors, limitations, and prospects for neoteric clinical use.
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Verma, Abhishek, e Ankit Awasthi. "Developing non-viral or viral vectors for efficient and targeted delivery of genetic material, such as DNA or RNA, for gene therapy applications". Pharmaspire 15, n.º 04 (2023): 243–56. http://dx.doi.org/10.56933/pharmaspire.2023.15137.
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Gene therapy has emerged as a promising approach for treating a wide range of genetic and acquired diseases by introducing or modifying genetic material within cells. To achieve successful gene therapy, efficient and precise delivery of genetic material, such as DNA or RNA, to target cells is essential. This abstract explores the development of both non-viral and viral vectors for the delivery of genetic material in gene therapy applications. Non-viral vectors, including lipid nanoparticles (LNPs), polymer-based carriers, and cell-penetrating peptides, have gained significant attention due to their safety profile and ease of production. These vectors are designed to protect genetic material from degradation, facilitate cellular uptake, and release the cargo at the desired location. Recent advancements in nanotechnology have enabled the design of customizable non-viral vectors with enhanced delivery efficiency and reduced offtarget effects. Viral vectors, on the other hand, harness the natural infectivity of viruses to transport genetic material into target cells. Retroviruses, lentiviruses, adenoviruses, and adeno-associated viruses (AAVs) are commonly used viral vectors in gene therapy. Viral vectors offer high transduction efficiency but may trigger immune responses or pose risks of insertional mutagenesis. Efforts in vector engineering have led to the development of safer viral vectors with improved targeting capabilities and reduced immunogenicity. AAVs, in particular, have gained prominence due to their ability to achieve long-lasting gene expression with minimal adverse effects. Targeted delivery strategies aim to enhance vector specificity, ensuring that genetic material reaches the intended cell type or tissue. These strategies include modifying vector surface proteins, employing tissue-specific promoters, or utilizing ligand-receptor interactions. In conclusion, the successful application of gene therapy relies on the development of efficient and targeted delivery systems for genetic material. Non-viral and viral vectors offer distinct advantages and continue to evolve to meet the demands of gene therapy applications. Advances in vector design, safety, and targeting strategies hold promise for the continued progress of gene therapy as a transformative medical intervention.
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Perumalsamy, Nandhini, Rohit Sharma, Muthukumaravel Subramanian e Shriram Ananganallur Nagarajan. "Hard Ticks as Vectors: The Emerging Threat of Tick-Borne Diseases in India". Pathogens 13, n.º 7 (2 de julho de 2024): 556. http://dx.doi.org/10.3390/pathogens13070556.
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Hard ticks (Ixodidae) play a critical role in transmitting various tick-borne diseases (TBDs), posing significant global threats to human and animal health. Climatic factors influence the abundance, diversity, and vectorial capacity of tick vectors. It is imperative to have a comprehensive understanding of hard ticks, pathogens, eco-epidemiology, and the impact of climatic changes on the transmission dynamics of TBDs. The distribution and life cycle patterns of hard ticks are influenced by diverse ecological factors that, in turn, can be impacted by changes in climate, leading to the expansion of the tick vector’s range and geographical distribution. Vector competence, a pivotal aspect of vectorial capacity, involves the tick’s ability to acquire, maintain, and transmit pathogens. Hard ticks, by efficiently feeding on diverse hosts and manipulating their immunity through their saliva, emerge as competent vectors for various pathogens, such as viruses, parasites and bacteria. This ability significantly influences the success of pathogen transmission. Further exploration of genetic diversity, population structure, and hybrid tick vectors is crucial, as they play a substantial role in influencing vector competence and complicating the dynamics of TBDs. This comprehensive review deals with important TBDs in India and delves into a profound understanding of hard ticks as vectors, their biology, and the factors influencing their vector competence. Given that TBDs continue to pose a substantial threat to global health, the review emphasizes the urgency of investigating tick control strategies and advancing vaccine development. Special attention is given to the pivotal role of population genetics in comprehending the genetic diversity of tick populations and providing essential insights into their adaptability to environmental changes.
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Weklak, Denice, Daniel Pembaur, Georgia Koukou, Franziska Jönsson, Claudia Hagedorn e Florian Kreppel. "Genetic and Chemical Capsid Modifications of Adenovirus Vectors to Modulate Vector–Host Interactions". Viruses 13, n.º 7 (2 de julho de 2021): 1300. http://dx.doi.org/10.3390/v13071300.
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Adenovirus-based vectors are playing an important role as efficacious genetic vaccines to fight the current COVID-19 pandemic. Furthermore, they have an enormous potential as oncolytic vectors for virotherapy and as vectors for classic gene therapy. However, numerous vector–host interactions on a cellular and noncellular level, including specific components of the immune system, must be modulated in order to generate safe and efficacious vectors for virotherapy or classic gene therapy. Importantly, the current widespread use of Ad vectors as vaccines against COVID-19 will induce antivector immunity in many humans. This requires the development of strategies and techniques to enable Ad-based vectors to evade pre-existing immunity. In this review article, we discuss the current status of genetic and chemical capsid modifications as means to modulate the vector–host interactions of Ad-based vectors.
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Powell, Jeffrey. "Genetic Variation in Insect Vectors: Death of Typology?" Insects 9, n.º 4 (11 de outubro de 2018): 139. http://dx.doi.org/10.3390/insects9040139.
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The issue of typological versus population thinking in biology is briefly introduced and defined. It is then emphasized how population thinking is most relevant and useful in vector biology. Three points are made: (1) Vectors, as they exist in nature, are genetically very heterogeneous. (2) Four examples of how this is relevant in vector biology research are presented: Understanding variation in vector competence, GWAS, identifying the origin of new introductions of invasive species, and resistance to inbreeding. (3) The existence of high levels of vector genetic heterogeneity can lead to failure of some approaches to vector control, e.g., use of insecticides and release of sterile males (SIT). On the other hand, vector genetic heterogeneity can be harnessed in a vector control program based on selection for refractoriness.
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Kienesberger, Sabine, Gregor Gorkiewicz, Martina M. Joainig, Sylvia R. Scheicher, Eva Leitner e Ellen L. Zechner. "Development of Experimental Genetic Tools for Campylobacter fetus". Applied and Environmental Microbiology 73, n.º 14 (18 de maio de 2007): 4619–30. http://dx.doi.org/10.1128/aem.02407-06.
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ABSTRACT Molecular analysis of the virulence mechanisms of the emerging pathogen Campylobacter fetus has been hampered by the lack of genetic tools. We report the development and functional analysis of Escherichia coli-Campylobacter shuttle vectors that are appropriate for C. fetus. Some vectors were constructed based on the known Campylobacter coli plasmid pIP1455 replicon, which confers a wide host range in Campylobacter spp. Versatility in directing gene expression was achieved by introducing a strong C. fetus promoter. The constructions carry features necessary and sufficient to detect the expression of phenotypic markers, including molecular reporter genes in both subspecies of C. fetus, while retaining function in C. jejuni. The capacity to express several gene products from different vectors in a single host can be advantageous but requires distinct plasmid replicons. To this end, replication features derived from a cryptic plasmid of C. fetus subsp. venerealis strain 4111/108, designated pCFV108, were adapted for a compatible series of constructions. The substitution of the C. coli replication elements reduced vector size while apparently limiting the host range to C. fetus. The complementation of a ciprofloxacin-resistant mutant phenotype via vector-driven gyrA expression was verified. Cocultivation demonstrated that shuttle vectors based on the pCFV108 replicon were compatible with pIP1455 replication functions, and the stable maintenance of two plasmids in a C. fetus subsp. venerealis host over several months was observed. The application of both vector types will facilitate the investigation of the genetics and cellular interactions of the emerging pathogen C. fetus.
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Criscione, Frank, David A. O’Brochta e William Reid. "Genetic technologies for disease vectors". Current Opinion in Insect Science 10 (agosto de 2015): 90–97. http://dx.doi.org/10.1016/j.cois.2015.04.012.
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Krasnykh, Victor N., Joanne T. Douglas e Victor W. van Beusechem. "Genetic Targeting of Adenoviral Vectors". Molecular Therapy 1, n.º 5 (maio de 2000): 391–405. http://dx.doi.org/10.1006/mthe.2000.0062.
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Kojic, Milorad, e William K. Holloman. "Shuttle vectors for genetic manipulations in Ustilago maydis". Canadian Journal of Microbiology 46, n.º 4 (1 de abril de 2000): 333–38. http://dx.doi.org/10.1139/w00-002.
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Shuttle vectors with new or improved features were constructed to enable facile genetic manipulations in the plant pathogen Ustilago maydis. Sets of plasmids selectable in media containing geneticin, carboxin, nourseothricin, or hygromycin, able to replicate autonomously, to transform U. maydis by integration, and to express foreign genes under control of the homologous glyceraldehyde-3-phosphate dehydrogenase promoter, were built upon a common pUC19 vector backbone. This permits a large number of choices for a cloning site, blue/white screening for recombinant plasmids, rapid transfer of a cloned DNA fragment between plasmids, and choice of several dominant drug-resistance markers for selection in U. maydis.Key words: G418, carboxin, nourseothricin, hygromycin, expression vectors.
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Redder, Peter, e Patrick Linder. "New Range of Vectors with a Stringent 5-Fluoroorotic Acid-Based Counterselection System for Generating Mutants by Allelic Replacement in Staphylococcus aureus". Applied and Environmental Microbiology 78, n.º 11 (23 de março de 2012): 3846–54. http://dx.doi.org/10.1128/aem.00202-12.
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ABSTRACTWe have developed a range of vectors for allelic replacements inStaphylococcus aureusto facilitate genetic work in this opportunistic pathogen. The central feature of the vector range is a selection/counterselection system that takes advantage of the 5-fluoroorotic acid (FOA) resistance and pyrimidine prototrophy caused by the loss and gain, respectively, of thepyrFandpyrEgenes. This system allows for stringent counterselection of the vectors during the second homologous recombination of a classic allelic replacement. The basic vector pRLY2, which contains thepyrFEgenes fromBacillus subtilis, was combined with chloramphenicol, erythromycin, and tetracycline resistance genes and four different versions of nonreplicative or conditionally replicative origins of replication. The choice between these 12 different pRLY vectors allows for high versatility and ensures that the vectors can be used in virtually any genetic background. Finally, as proof of concept, we present six deletions or modifications of components in theS. aureusdegradosome as well as the operon containing thecshBDEAD box helicase.
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Cody, Will B., e Herman B. Scholthof. "Plant Virus Vectors 3.0: Transitioning into Synthetic Genomics". Annual Review of Phytopathology 57, n.º 1 (25 de agosto de 2019): 211–30. http://dx.doi.org/10.1146/annurev-phyto-082718-100301.
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Plant viruses were first implemented as heterologous gene expression vectors more than three decades ago. Since then, the methodology for their use has varied, but we propose it was the merging of technologies with virology tools, which occurred in three defined steps discussed here, that has driven viral vector applications to date. The first was the advent of molecular biology and reverse genetics, which enabled the cloning and manipulation of viral genomes to express genes of interest (vectors 1.0). The second stems from the discovery of RNA silencing and the development of high-throughput sequencing technologies that allowed the convenient and widespread use of virus-induced gene silencing (vectors 2.0). Here, we briefly review the events that led to these applications, but this treatise mainly concentrates on the emerging versatility of gene-editing tools, which has enabled the emergence of virus-delivered genetic queries for functional genomics and virology (vectors 3.0).
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NIJHOF, A. M. "Genetic make-up of arthropod vectors". Revue Scientifique et Technique de l'OIE 34, n.º 1 (1 de abril de 2015): 113–22. http://dx.doi.org/10.20506/rst.34.1.2348.
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Carlson, J., K. Olson, S. Higgs e B. Beaty. "Molecular Genetic Manipulation of Mosquito Vectors". Annual Review of Entomology 40, n.º 1 (janeiro de 1995): 359–88. http://dx.doi.org/10.1146/annurev.en.40.010195.002043.
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Lee, Joon-Yong, Min-Soeng Kim e Ju-Jang Lee. "Compact Genetic Algorithms using belief vectors". Applied Soft Computing 11, n.º 4 (junho de 2011): 3385–401. http://dx.doi.org/10.1016/j.asoc.2011.01.010.
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Ponnazhagan, Selvarangan. "Adenoassociated Virus Vectors for Genetic Immunization". Immunologic Research 26, n.º 1-3 (2002): 247–54. http://dx.doi.org/10.1385/ir:26:1-3:247.
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Li, Shu-fen, Hua-lin Wang, Zhi-hong Hu e Fei Deng. "Genetic modification of baculovirus expression vectors". Virologica Sinica 27, n.º 2 (abril de 2012): 71–82. http://dx.doi.org/10.1007/s12250-012-3236-y.
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Xiao, Cheng Yong, Bo Qiang Shi, Zhi Jun Hao e Shuang Ming Zhu. "Gear Incipient Diagnosing Based on EEMD and Genetic-Support Vector Machine". Applied Mechanics and Materials 397-400 (setembro de 2013): 2104–10. http://dx.doi.org/10.4028/www.scientific.net/amm.397-400.2104.
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Due to the incipient fault attributes of gear are not obvious, So a hybrid diagnosis model to gear diagnosing based on Ensemble Empirical Mode Decomposition (EEMD) and Genetic-Support Vector Machine (GSVM) was proposed. With the method of EEMD,the gear vibration signals are adaptively decomposed into a finite number of Intrinsic Mode Function (IMF),which can alleviate model mixing that may appear in conventional EMD method. It calculates the energy character vectors of every IMF components,energy feature extracted from a number of IMFs that contained the most dominant fault information could serve as input genetic-vectors of support vector machine. The proposed model is applied to the gear testing system, and the results show that the diagnosis approach was effectively.
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Wang, Xutong, Mandi Wang, Jian Sun, Xiaolei Qu, Shixin Wang e Tingting Sun. "Establishment of an Efficient Genetic Transformation System in Sanghuangporus baumii". Journal of Fungi 10, n.º 2 (8 de fevereiro de 2024): 137. http://dx.doi.org/10.3390/jof10020137.
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(1) Background: Sanghuangporus baumii, a valuable medicinal fungus, has limited studies on its gene function due to the lack of a genetic transformation system. (2) Methods: This study aimed to establish an efficient Agrobacterium tumefaciens-mediated transformation (ATMT) system for S. baumii. This study involved cloning the promoter (glyceraldehyde-3-phosphate dehydrogenase, gpd) of S. baumii, reconstructing the transformation vector, optimizing the treatment of receptor tissues, and inventing a new method for screening positive transformants. (3) Results: The established ATMT system involved replacing the CaMV35S promoter of pCAMBIA-1301 with the gpd promoter of S. baumii to construct the pCAMBIA-SH-gpd transformation vector. The vectors were then transferred to A. tumefaciens (EHA105) for infection. This study found that the transformation efficiency was higher in the infection using pCAMBIA-SH-gpd vectors than using pCAMBIA-1301 vectors. The mycelia of S. baumii were homogenized for 20 s and collected as the genetic transformation receptor. After 20 min of co-culture and 48 h of incubation in 15 mL PDL medium at 25 °C, new colonies grew. (4) Conclusions: These colonies were transferred to PDA medium (hygromycin 4 μg/mL, cefotaxime 300 μg/mL), and the transformation efficiency was determined to be 33.7% using PCR.
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Moskalev, A. V., B. Yu Gumilevskiy, A. V. Apchel e V. N. Tsygan. "Genetic updating and marks of cellular lines". Bulletin of the Russian Military Medical Academy 22, n.º 3 (15 de dezembro de 2020): 168–75. http://dx.doi.org/10.17816/brmma50555.
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Abstract. Despite great advances in the biology of stem cells, there are still many dark spots. Genetic modification techniques, which can be used to track the lines of different cells, primarily stem cells, help to solve this problem. Various methods of biotechnology research are considered, allowing to evaluate the options of introducing new genes into cells and even whole organisms, as well as methods of controlling their expression in time and space, their activation, differentiation and decrease in functional activity, expression of several target genes. Options with multi-cystron vectors encoding several proteins are described. Options for introducing genes using plasmids, electroportation of their disadvantages and advantages are characterized. The most promising and the safest is a retroviral vector using lentivirus vectors capable of generating additional copies of itself, which is very important in the field of biotechnology security. A line of packing cells, usually 293T cells, is used to produce a viral vector. Prospects for the use of adenovirus and adenoassociated vectors are characterized. The achievement of modern biotechnology methods is the system of short palindrome repetitions located in groups, which is a unique tool for genome editing. At the heart of this system is the process of cutting out sequences of deoxyribonucleic acid, which are permanent and which are supported by cells regardless of subsequent divisions or changes in condition. The system allows geneticists and medical researchers to edit parts of the genome by removing, adding or modifying successive sites of deoxyribonucleic acid. An important problem with biotechnology methods is how to control the expression of transgenes. Today, it is quite effective to control expression with a factor present in the gene delivery vector itself and which is only active in a certain type of cell. Endonuclease bacteriophage P1 is used to regulate transgene expression, which cuts deoxyribonucleic acid only at specific sites. This system is introduced in both eukaryotic and prokaryotic systems.
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CHEN, PENG, CHUNMEI LIU, LEGAND BURGE, MOHAMMAD MAHMOOD, WILLIAM SOUTHERLAND e CLAY GLOSTER. "PROTEIN FOLD CLASSIFICATION WITH GENETIC ALGORITHMS AND FEATURE SELECTION". Journal of Bioinformatics and Computational Biology 07, n.º 05 (outubro de 2009): 773–88. http://dx.doi.org/10.1142/s0219720009004321.
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Protein fold classification is a key step to predicting protein tertiary structures. This paper proposes a novel approach based on genetic algorithms and feature selection to classifying protein folds. Our dataset is divided into a training dataset and a test dataset. Each individual for the genetic algorithms represents a selection function of the feature vectors of the training dataset. A support vector machine is applied to each individual to evaluate the fitness value (fold classification rate) of each individual. The aim of the genetic algorithms is to search for the best individual that produces the highest fold classification rate. The best individual is then applied to the feature vectors of the test dataset and a support vector machine is built to classify protein folds based on selected features. Our experimental results on Ding and Dubchak's benchmark dataset of 27-class folds show that our approach achieves an accuracy of 71.28%, which outperforms current state-of-the-art protein fold predictors.
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Zouache, Karima, Albin Fontaine, Anubis Vega-Rua, Laurence Mousson, Jean-Michel Thiberge, Ricardo Lourenco-De-Oliveira, Valérie Caro, Louis Lambrechts e Anna-Bella Failloux. "Three-way interactions between mosquito population, viral strain and temperature underlying chikungunya virus transmission potential". Proceedings of the Royal Society B: Biological Sciences 281, n.º 1792 (7 de outubro de 2014): 20141078. http://dx.doi.org/10.1098/rspb.2014.1078.
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Interactions between pathogens and their insect vectors in nature are under the control of both genetic and non-genetic factors, yet most studies on mosquito vector competence for human pathogens are conducted in laboratory systems that do not consider genetic and/or environmental variability. Evaluating the risk of emergence of arthropod-borne viruses (arboviruses) of public health importance such as chikungunya virus (CHIKV) requires a more realistic appraisal of genetic and environmental contributions to vector competence. In particular, sources of variation do not necessarily act independently and may combine in the form of interactions. Here, we measured CHIKV transmission potential by the mosquito Aedes albopictus in all combinations of six worldwide vector populations, two virus strains and two ambient temperatures (20°C and 28°C). Overall, CHIKV transmission potential by Ae. albopictus strongly depended on the three-way combination of mosquito population, virus strain and temperature. Such genotype-by-genotype-by-environment (G × G × E) interactions question the relevance of vector competence studies conducted with a simpler set of conditions. Our results highlight the need to account for the complex interplay between vectors, pathogens and environmental factors to accurately assess the potential of vector-borne diseases to emerge.
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Bogoslovskaya, E. V., D. V. Glazkova, G. A. Shipulin e V. V. Pokrovskii. "SAFETY OF RETROVIRAL VECTORS IN GENE THERAPY". Annals of the Russian academy of medical sciences 67, n.º 10 (10 de outubro de 2012): 55–61. http://dx.doi.org/10.15690/vramn.v67i10.417.
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Retroviral vectors are widely used in gene therapy and found to be an effective tool for the delivery of genetic constructs into cells. A unique feature of these vectors is the ability to incorporate therapeutic genes into a chromosome that ensures its passage to all progeny cells and enables to cure the diseases requiring genetic correction of dividing cells such as hematopoietic cells or skin cells. Retroviral vectors have been successfully used in gene therapy clinical trials for the treatment of 2 forms of severe combined immunodeficiencies and some other hereditary blood disorders. However, the integration of the vector into the chromosome was accompanied by genotoxicity and caused development of hematologic malignancies in several patients. Later it was shown that genotoxicity is not a general feature of retroviral vectors but it depends on many factors. In the present article we discuss safety issues concerning the use of different retroviral vectors in gene therapy. The description of modern vectors which designed to avoid the genotoxicity and other possible side effects are given.
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Sedova, E. S., D. N. Shcherbinin, A. I. Migunov, Yu A. Smirnov, D. Yu Logunov, M. M. Shmarov, L. M. Tsybalova, B. S. Naroditskiĭ, O. I. Kiselev e A. L. Gintsburg. "Recombinant Influenza Vaccines". Acta Naturae 4, n.º 4 (15 de dezembro de 2012): 17–27. http://dx.doi.org/10.32607/20758251-2012-4-4-17-27.
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This review covers the problems encountered in the construction and production of new recombinant influenza vaccines. New approaches to the development of influenza vaccines are investigated; they include reverse genetics methods, production of virus-like particles, and DNA- and viral vector-based vaccines. Such approaches as the delivery of foreign genes by DNA- and viral vector-based vaccines can preserve the native structure of antigens. Adenoviral vectors are a promising gene-delivery platform for a variety of genetic vaccines. Adenoviruses can efficiently penetrate the human organism through mucosal epithelium, thus providing long-term antigen persistence and induction of the innate immune response. This review provides an overview of the practicability of the production of new recombinant influenza cross-protective vaccines on the basis of adenoviral vectors expressing hemagglutinin genes of different influenza strains.
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Arumugam, Paritha, e Punam Malik. "Genetic Therapy for Beta-Thalassemia: From the Bench to the Bedside". Hematology 2010, n.º 1 (4 de dezembro de 2010): 445–50. http://dx.doi.org/10.1182/asheducation-2010.1.445.
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AbstractBeta-thalassemia is a genetic disorder with mutations in the β-globin gene that reduce or abolish β-globin protein production. Patients with β-thalassemia major (Cooley's anemia) become severely anemic by 6 to 18 months of age, and are transfusion dependent for life, while those with thalassemia intermedia, a less-severe form of thalassemia, are intermittently or rarely transfused. An allogeneically matched bone marrow transplant is curative, although it is restricted to those with matched donors. Gene therapy holds the promise of “fixing” one's own bone marrow cells by transferring the normal β-globin or γ-globin gene into hematopoietic stem cells (HSCs) to permanently produce normal red blood cells. Requirements for effective gene transfer for the treatment of β-thalassemia are regulated, erythroid-specific, consistent, and high-level β-globin or γ-globin expression. Gamma retroviral vectors have had great success with immune-deficiency disorders, but due to vector-associated limitations, they have limited utility in hemoglobinopathies. Lentivirus vectors, on the other hand, have now been shown in several studies to correct mouse and animal models of thalassemia. The immediate challenges of the field as it moves toward clinical trials are to optimize gene transfer and engraftment of a high proportion of genetically modified HSCs and to minimize the adverse consequences that can result from random integration of vectors into the genome by improving current vector design or developing novel vectors. This article discusses the current state of the art in gene therapy for β-thalassemia and some of the challenges it faces in human trials.
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Bourgade, Barbara, James Millard, Christopher M. Humphreys, Nigel P. Minton e M. Ahsanul Islam. "Enabling Ethanologenesis in Moorella thermoacetica through Construction of a Replicating Shuttle Vector". Fermentation 8, n.º 11 (28 de outubro de 2022): 585. http://dx.doi.org/10.3390/fermentation8110585.
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Replicating plasmid shuttle vectors are key tools for efficient genetic and metabolic engineering applications, allowing the development of sustainable bioprocesses using non-model organisms with unique metabolic capabilities. To date, very limited genetic manipulation has been achieved in the thermophilic acetogen, Moorella thermoacetica, partly due to the lack of suitable shuttle vectors. However, M. thermoacetica has considerable potential as an industrial chassis organism, which can only be unlocked if reliable and effective genetic tools are in place. This study reports the construction of a replicating shuttle vector for M. thermoacetica through the identification and implementation of a compatible Gram-positive replicon to allow plasmid maintenance within the host. Although characterisation of plasmid behaviour proved difficult, the designed shuttle vector was subsequently applied for ethanologenesis, i.e., ethanol production in this organism. The non-native ethanologenesis in M. thermoacetica was achieved via plasmid-borne overexpression of the native aldh gene and heterologous expression of Clostridium autoethanogenum adhE1 gene. This result demonstrates the importance of the developed replicating plasmid vector for genetic and metabolic engineering efforts in industrially important M. thermoacetica.
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Moon, Seung-Hyun, e Yourim Yoon. "Genetic Mean Reversion Strategy for Online Portfolio Selection with Transaction Costs". Mathematics 10, n.º 7 (26 de março de 2022): 1073. http://dx.doi.org/10.3390/math10071073.
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Online portfolio selection (OLPS) is a procedure for allocating portfolio assets using only past information to maximize an expected return. There have been successful mean reversion strategies that have achieved large excess returns on the traditional OLPS benchmark datasets. We propose a genetic mean reversion strategy that evolves a population of portfolio vectors using a hybrid genetic algorithm. Each vector represents the proportion of the portfolio assets, and our strategy chooses the best vector in terms of the expected returns on every trading day. To test our strategy, we used the price information of the S&P 500 constituents from 2000 to 2017 and compared various strategies for online portfolio selection. Our hybrid genetic framework successfully evolved the portfolio vectors; therefore, our strategy outperformed the other strategies when explicit or implicit transaction costs were incurred.
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Yildirim, Özal, e Ulas Baran Baloglu. "Heartbeat type classification with optimized feature vectors". An International Journal of Optimization and Control: Theories & Applications (IJOCTA) 8, n.º 2 (12 de abril de 2018): 170–75. http://dx.doi.org/10.11121/ijocta.01.2018.00567.
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In this study, a feature vector optimization based method has been proposed for classification of the heartbeat types. Electrocardiogram (ECG) signals of five different heartbeat type were used for this aim. Firstly, wavelet transform (WT) method were applied on these ECG signals to generate all feature vectors. Optimizing these feature vectors is provided by performing particle swarm optimization (PSO), genetic search, best first, greedy stepwise and multi objective evoluationary algorithms on these vectors. These optimized feature vectors are later applied to the classifier inputs for performance evaluation. A comprehensive assessment was presented for the determination of optimized feature vectors for ECG signals and best-performing classifier for these optimized feature vectors was determined.
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Mastakov, Mihail Y., Kristin Baer, C. Wymond Symes, Claudia B. Leichtlein, Robert M. Kotin e Matthew J. During. "Immunological Aspects of Recombinant Adeno-Associated Virus Delivery to the Mammalian Brain". Journal of Virology 76, n.º 16 (15 de agosto de 2002): 8446–54. http://dx.doi.org/10.1128/jvi.76.16.8446-8454.2002.
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ABSTRACT Recombinant adeno-associated viruses (rAAV) are highly efficient vectors for gene delivery into the central nervous system (CNS). However, host inflammatory and immune responses may play a critical role in limiting the use of rAAV vectors for gene therapy and functional genomic studies in vivo. Here, we evaluated the effect of repeated injections of five rAAV vectors expressing different genetic sequences (coding or noncoding) in a range of combinations into the rat brain. Specifically, we wished to determine whether a specific immune or inflammatory response appeared in response to the vector and/or the transgene protein after repeated injections under conditions of mannitol coinjection. We show that readministration of the same rAAV to the CNS is possible if the interval between the first and second injection is more than 4 weeks. Furthermore, our data demonstrate that rAAV vectors carrying different genetic sequences can be administered at intervals of 2 weeks. Our data therefore suggest that the AAV capsid structure is altered by the vector genetic sequence, such that secondary structures of the single-stranded genome have an impact on the antigenicity of the virus. This study provides guidelines for more rational design of gene transfer studies in the rodent brain and, in addition, suggests the use of repeated administration of rAAV as a viable form of therapy for the treatment of chronic diseases.
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Young, Won-Bin, Gary L. Lindberg e Charles J. Link. "DNA Methylation of Helper Virus Increases Genetic Instability of Retroviral Vector Producer Cells". Journal of Virology 74, n.º 7 (1 de abril de 2000): 3177–87. http://dx.doi.org/10.1128/jvi.74.7.3177-3187.2000.
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ABSTRACT Retroviral vector producer cells (VPC) have been considered genetically stable. A clonal cell population exhibiting a uniform vector integration pattern is used for sustained vector production. Here, we observed that the vector copy number is increased and varied in a population of established LTKOSN.2 VPC. Among five subclones of LTKOSN.2 VPC, the vector copy number ranged from 1 to approximately 29 copies per cell. A vector superinfection experiment and Northern blot analysis demonstrated that suppression of helper virus gene expression decreased Env-receptor interference and allowed increased superinfection. The titer production was tightly associated with helper virus gene expression and varied between 0 and 2.2 × 105 CFU/ml in these subclones. In one analyzed subclone, the number of integrated vectors increased from one copy per cell to nine copies per cell during a 31-day period. Vector titer was reduced from 1.5 × 105 CFU to an undetectable level. To understand the mechanism involved, helper virus and vectors were examined for DNA methylation status by methylation-sensitive restriction enzyme digestion. We demonstrated that DNA methylation of helper virus 5′ long terminal repeat occurred in approximately 2% of the VPC population per day and correlated closely with inactivation of helper virus gene expression. In contrast, retroviral vectors did not exhibit significant methylation and maintained consistent transcription activity. Treatment with 5-azacytidine, a methylation inhibitor, partially reversed the helper virus DNA methylation and restored a portion of vector production. The preference for methylation of helper virus sequences over vector sequences may have important implications for host-virus interaction. Designing a helper virus to overcome cellular DNA methylation may therefore improve vector production. The maintenance of increased viral envelope-receptor interference might also prevent replication-competent retrovirus formation.
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Schnepp, Bruce C., K. Reed Clark, Dori L. Klemanski, Christina A. Pacak e Philip R. Johnson. "Genetic Fate of Recombinant Adeno-Associated Virus Vector Genomes in Muscle". Journal of Virology 77, n.º 6 (15 de março de 2003): 3495–504. http://dx.doi.org/10.1128/jvi.77.6.3495-3504.2003.
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ABSTRACT Recombinant adeno-associated virus (rAAV) vectors are promising human gene transfer vectors, because they mediate long-term gene expression in vivo. The vector DNA form responsible for sustained gene expression has not been clearly defined, but it has been presumed that the vector integrates to some degree and persists in this manner. Using two independent methods, we were unable to identify rAAV integrants in mouse muscle. In the first approach, we were unable to recover host cell-vector DNA junctions from a lambda phage library generated using transduced mouse muscle DNA that contained a high vector copy number. Following this result, we devised a PCR assay based on the principle that integrated rAAV vector sequences could be amplified using primers specific for mouse interspersed repetitive sequences (B1 elements). Using this assay, we analyzed transduced mouse muscle DNA isolated from 6 to 57 weeks after injection and did not detect amplification above background levels. Based on the demonstrated sensitivity of the assay, these results suggested that >99.5% of vector DNA was not integrated. Additional analyses using a novel DNA exonuclease showed that the majority of the rAAV vector DNA in muscle persisted over time as transcriptionally active monomeric and concatameric episomes.
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Cattoglio, Claudia, Barbara Felice, Davide Cittaro, Annarita Miccio, Giuliana Ferrari, Alessandra Recchia, Lucilla Luzi e Fulvio Mavilio. "Transcription Factor Binding Sites Are Genetic Determinant of Retroviral Integration in the Human Genome". Blood 112, n.º 11 (16 de novembro de 2008): 820. http://dx.doi.org/10.1182/blood.v112.11.820.820.
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Abstract Gamma-retroviruses and lentiviruses integrate non-randomly in mammalian genomes, with specific preferences for active chromatin, promoters and regulatory regions. Gamma-retroviral gene transfer vectors show a high frequency of insertional gene activation, and may induce neoplastic or pre-neoplastic clonal expansions in patients treated with genetically modified cells. An analysis of >10,000 integration sites of a Moloney leukemia virus (MLV)-derived vector in human CD34+ hematopoietic progenitors showed that genes involved the control of growth, differentiation and development of the hematopoietic and immune system are targeted at high frequency and enriched in integration hot spots, suggesting that the cell gene expression program is instrumental in directing MLV integration. To investigate the role of transcriptional regulatory networks in retroviral target site selection, we analyzed the distribution of transcription factor binding sites (TFBSs) flanking >4,000 MLV- and HIV-derived proviruses in human hematopoietic and non-hematopoietic cells. We show that MLV vectors integrate in genomic regions enriched in cell-type specific subsets of TFBSs, independently from their relative position with respect to genes and transcription start sites. Conversely, HIV vectors appear to avoid TFBS-rich genomic regions. Hierarchical clustering and a principal component analysis of TFBSs flanking retroviral integration sites in CD34+ and HeLa cells showed that TFBS subsets are vector- and cell type-specific. Analysis of sequences flanking the integration sites of vectors carrying mutations in their long terminal repeats (LTRs), and of HIV vectors packaged with a MLV integrase, indicates that the MLV integrase and LTR enhancer are the viral determinants of the selection of TFBS-rich regions in the genome. Chromatin immunoprecipitation analysis shows that transcription factors bind the LTR enhancers in the cell nucleus before integration, and may therefore synergize with the integrase in tethering retroviral pre-integration complexes to transcriptionally active regulatory regions. This study identifies TFBSs as differential genomic determinants of retroviral target site selection in the human genome, and indicates that gamma-retroviruses and lentiviruses have evolved dramatically different strategies to interact with the host cell chromatin. These differences predict a higher risk in using gamma-retroviral vs. lentiviral vectors for human gene therapy applications, independently from the design of the vector and the transgene expression cassette.
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Pless, Evlyn, Norah P. Saarman, Jeffrey R. Powell, Adalgisa Caccone e Giuseppe Amatulli. "A machine-learning approach to map landscape connectivity inAedes aegyptiwith genetic and environmental data". Proceedings of the National Academy of Sciences 118, n.º 9 (22 de fevereiro de 2021): e2003201118. http://dx.doi.org/10.1073/pnas.2003201118.
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Mapping landscape connectivity is important for controlling invasive species and disease vectors. Current landscape genetics methods are often constrained by the subjectivity of creating resistance surfaces and the difficulty of working with interacting and correlated environmental variables. To overcome these constraints, we combine the advantages of a machine-learning framework and an iterative optimization process to develop a method for integrating genetic and environmental (e.g., climate, land cover, human infrastructure) data. We validate and demonstrate this method for theAedes aegyptimosquito, an invasive species and the primary vector of dengue, yellow fever, chikungunya, and Zika. We test two contrasting metrics to approximate genetic distance and find Cavalli-Sforza–Edwards distance (CSE) performs better than linearized FST. The correlation (R) between the model’s predicted genetic distance and actual distance is 0.83. We produce a map of genetic connectivity forAe. aegypti’s range in North America and discuss which environmental and anthropogenic variables are most important for predicting gene flow, especially in the context of vector control.
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Neuwelt, Edward A., Michael A. Pagel, Alfred Geller e Leslie L. Muldoon. "Gene replacement therapy in the central nervous system: Viral vector-mediated therapy of global neurodegenerative disease". Behavioral and Brain Sciences 18, n.º 1 (março de 1995): 1–9. http://dx.doi.org/10.1017/s0140525x00037237.
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AbstractThis target article describes the current state of global gene replacement in the brain using viral vectors and assesses possible solutions to some of the many problems inherent in gene therapy of the central nervous system (CNS). Gene replacement therapy in the CNS is a potential means of producing a stable expression of normal human proteins in deficient cells and thus curing certain genetically inherited enzyme deficiencies and metabolic diseases as well as cancers. The two major issues to be addressed in CNS gene replacement are the delivery of genetic material to the brain and the expression of recombinant genetic material in target cells within the CNS. Focal inoculation of recombinant virions or other genetic vectors has limitations in global CNS disease. A new approach is the blood-brain barrier (BBB) disruption technique developed in this laboratory, in which hypertonic mannitol transiently shrinks the BBB endothelium, allowing passage of high molecular weight compounds and even viruses. Gene therapy of the CNS will require a viral vector system that allows long-term, nontoxic gene expression in neurons or glial cells. Retroviral vectors have limitations in CNS gene replacement, although they are suitable for expressing recombinant genes in intracerebral grafts, or toxic genes in brain tumors. Using mutant neurotropic viruses with reduced neurotoxicity (such as defective herpes simplex virus type I [HSV-1], the HSV-1 amplicon vector system we have developed, or adenovirus mutants) has potential for direct treatment of neurons. Injecting these vectors into rodent brains can lead to stable expression of foreign genetic material in postmitotic neuronal cells. We discuss our BBB disruption delivery technique, our defective HSV-1 amplicon vector system, and our feline model for the neuronal lysosomal storage disorder Gm2-gangliosidosis (Sandhoff disease), which may prove to be a useful model system for CNS gene therapy.
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Deng, C., K. R. Thomas e M. R. Capecchi. "Location of crossovers during gene targeting with insertion and replacement vectors". Molecular and Cellular Biology 13, n.º 4 (abril de 1993): 2134–40. http://dx.doi.org/10.1128/mcb.13.4.2134-2140.1993.
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Gene targeting was used to introduce nonselectable genetic changes into chromosomal loci in mouse embryo-derived stem cells. The nonselectable markers were linked to a selectable marker in both insertion- and replacement-type vectors, and the transfer of the two elements to the Hprt locus was assayed. When insertion vectors were used as substrates, the frequency of transfer was highly dependent upon the distance between the nonselectable marker and the double-strand break in the vector. A marker located close to the vector ends was frequently lost, suggesting that a double-strand gap repair activity is involved in vector integration. When replacement vectors were used, cotransfer of a selectable marker and a nonselectable marker 3 kb apart was over 50%, suggesting that recombination between vector and target often occurs near the ends of the vector. To illustrate the use of replacement vectors to transfer specific mutations to the genome, we describe targeting of the delta F508 mutation to the CFTR gene in mouse embryo-derived stem cells.
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Deng, C., K. R. Thomas e M. R. Capecchi. "Location of crossovers during gene targeting with insertion and replacement vectors." Molecular and Cellular Biology 13, n.º 4 (abril de 1993): 2134–40. http://dx.doi.org/10.1128/mcb.13.4.2134.
Texto completo da fonteResumo:
Gene targeting was used to introduce nonselectable genetic changes into chromosomal loci in mouse embryo-derived stem cells. The nonselectable markers were linked to a selectable marker in both insertion- and replacement-type vectors, and the transfer of the two elements to the Hprt locus was assayed. When insertion vectors were used as substrates, the frequency of transfer was highly dependent upon the distance between the nonselectable marker and the double-strand break in the vector. A marker located close to the vector ends was frequently lost, suggesting that a double-strand gap repair activity is involved in vector integration. When replacement vectors were used, cotransfer of a selectable marker and a nonselectable marker 3 kb apart was over 50%, suggesting that recombination between vector and target often occurs near the ends of the vector. To illustrate the use of replacement vectors to transfer specific mutations to the genome, we describe targeting of the delta F508 mutation to the CFTR gene in mouse embryo-derived stem cells.
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Altamiranda-Saavedra, Mariano, Nelson Naranjo-Díaz, Jan E. Conn e Margarita M. Correa. "Entomological parameters and population structure at a microgeographic scale of the main Colombian malaria vectors Anopheles albimanus and Anopheles nuneztovari". PLOS ONE 18, n.º 1 (6 de janeiro de 2023): e0280066. http://dx.doi.org/10.1371/journal.pone.0280066.
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Population subdivision among several neotropical malaria vectors has been widely evaluated; however, few studies have analyzed population variation at a microgeographic scale, wherein local environmental variables may lead to population differentiation. The aim of the present study was to evaluate the genetic and geometric morphometric structure of Anopheles nuneztovari and Anopheles albimanus in endemic localities of northwestern Colombia. Genetic and phenetic structures were evaluated using microsatellites markers and wing geometric morphometrics, respectively. In addition, entomological indices of importance in transmission were calculated. Results showed that the main biting peaks of Anopheles nuneztovari were between 20:00 and 22:00, whereas Anopheles albimanus exhibited more variation in biting times among localities. Infection in An. nuneztovari by Plasmodium spp. (IR: 4.35%) and the annual entomological inoculation rate (30.31), indicated high vector exposure and local transmission risk. We did not detect Plasmodium-infected An. albimanus in this study. In general, low genetic and phenetic subdivision among the populations of both vectors was detected using a combination of phenotypic, genetic and environmental data. The results indicated high regional gene flow, although local environmental characteristics may be influencing the wing conformation differentiation and behavioral variation observed in An. albimanus. Furthermore, the population subdivision detected by microsatellite markers for both species by Bayesian genetic analysis provides a more accurate picture of the current genetic structure in comparison to previous studies. Finally, the biting behavior variation observed for both vectors among localities suggests the need for continuous malaria vector surveys covering the endemic region to implement the most effective integrated local control interventions.
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Xu, Youqiang, Fei Tao, Cuiqing Ma e Ping Xu. "New Constitutive Vectors: Useful Genetic Engineering Tools for Biocatalysis". Applied and Environmental Microbiology 79, n.º 8 (15 de fevereiro de 2013): 2836–40. http://dx.doi.org/10.1128/aem.03746-12.
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ABSTRACTConstitutive vectors are useful tools for genetic engineering. Two constitutive vectors with high levels of expression and broad host ranges were developed and used in a range ofPseudomonashosts. The vectors showed superior characteristics compared to the inducible vectors as well as the potential to be used as improved genetic tools for biocatalysis.
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Saadi, Hogir. "Gene Therapy Approaches". Qubahan Academic Journal 1, n.º 1 (28 de março de 2021): 52–56. http://dx.doi.org/10.48161/qaj.v1n1a35.
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Gene therapy can be described broadly as the transfer of genetic material to control a disease or at least to enhance a patient's clinical status. The transformation of viruses into genetic shuttles is one of the core principles of gene therapy, which will introduce the gene of interest into the target tissue and cells. To do this, safe strategies have been invented, using many viral and non-viral vector delivery. Two major methods have emerged: modification in vivo and modification ex vivo. For gene therapeutic approaches which are focused on lifelong expression of the therapeutic gene, retrovirus, adenovirus, adeno-associated viruses are acceptable. Non-viral vectors are much less successful than viral vectors, but because of their low immune responses and their broad therapeutic DNA ability, they have advantages. The addition of viral functions such as receptor-mediated uptake and nuclear translocation of DNA may eventually lead to the development of an artificial virus in order to improve the role of non-viral vectors. For human use in genetic conditions, cancers and acquired illnesses, gene transfer techniques have been allowed. The ideal delivery vehicle has not been identified, although the accessible vector systems are capable of transporting genes in vivo into cells. Therefore, only with great caution can the present viral vectors be used in human beings and further progress in the production of vectors is required. Current progresses in our understanding of gene therapy approaches and their delivery technology, as well as the victors used to deliver therapeutic genes, are the primary goals of this review. For that reason, a literature search on PubMed and Google Scholar was carried out using different keywords.
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Hedley, Susan J., Aleksandr Krendelshchikov, Myung-Hee Kim, Jian Chen, Hui-Chen Hsu, John D. Mountz, David T. Curiel e Imre Kovesdi. "Assessment of Genetic Shielding for Adenovirus Vectors". Open Gene Therapy Journal 2, n.º 1 (27 de janeiro de 2009): 1–11. http://dx.doi.org/10.2174/1875037000902010001.
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Amalfitano, Andrea, Michael A. Hauser, Huimin Hu, Delila Serra, Catherine R. Begy e Jeffrey S. Chamberlain. "Production and Characterization of Improved Adenovirus Vectors with the E1, E2b, and E3 Genes Deleted". Journal of Virology 72, n.º 2 (1 de fevereiro de 1998): 926–33. http://dx.doi.org/10.1128/jvi.72.2.926-933.1998.
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ABSTRACT Adenovirus (Ad)-based vectors have great potential for use in the gene therapy of multiple diseases, both genetic and nongenetic. While capable of transducing both dividing and quiescent cells efficiently, Ad vectors have been limited by a number of problems. Most Ad vectors are engineered such that a transgene replaces the Ad E1a, E1b, and E3 genes; subsequently the replication-defective vector can be propagated only in human 293 cells that supply the deleted E1 gene functions intrans. Unfortunately, the use of high titers of E1-deleted vectors has been repeatedly demonstrated to result in low-level expression of viral genes still resident in the vector. In addition, the generation of replication-competent Ad (RCA) by recombination events with the E1 sequences residing in 293 cells further limits the usefulness of E1-deleted Ad vectors. We addressed these problems by isolating new Ad vectors deleted for the E1, E3, and the E2b gene functions. The new vectors can be readily grown to high titers and have several improvements, including an increased carrying capacity and a theoretically decreased risk for generating RCA. We have also demonstrated that the further block to Ad vector replication afforded by the deletion of both the E1 and E2b genes significantly diminished Ad late gene expression in comparison to a conventional E1-deleted vector, without destabilization of the modified vector genome. The results suggested that these modified vectors may be very useful both for in vitro and in vivo gene therapy applications.
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Mally, Manuela, e Guy R. Cornelis. "Genetic Tools for Studying Capnocytophaga canimorsus". Applied and Environmental Microbiology 74, n.º 20 (22 de agosto de 2008): 6369–77. http://dx.doi.org/10.1128/aem.01218-08.
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ABSTRACT Capnocytophaga canimorsus, a commensal bacterium from canine oral flora, has been isolated throughout the world from severe human infections caused by dog bites. Due to the low level of evolutionary relationship to Proteobacteria, genetic methods suitable for the genus Capnocytophaga needed to be established. Here, we show that Tn4351, derived from Bacteroides fragilis, could be introduced by conjugation into C. canimorsus and conferred resistance to erythromycin. By mapping and sequencing a naturally occurring plasmid isolated from a clinical isolate of C. canimorsus, we identified a repA gene that allowed us to construct Escherichia coli-Capnocytophaga shuttle vectors. Most commonly used antibiotic markers were not functional in C. canimorsus, but cefoxitin (cfxA), tetracycline (tetQ), and erythromycin (ermF) resistances could be used as markers for plasmid maintenance in C. canimorsus and even in some other Capnocytophaga spp. Shuttle vectors were introduced into C. canimorsus either by conjugation using the origin of transfer (oriT) of RP4 or by electrotransformation. Taking advantage of the promoter of ermF, an expression vector was constructed. Finally, a method that allows site-directed mutagenesis is described. All these genetic tools pave the way, not only for molecular studies of the pathogenesis of C. canimorsus, but also for studies of other oral Capnocytophaga species.
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Wintermantel, William M., e Gail C. Wisler. "Vector Specificity, Host Range, and Genetic Diversity of Tomato chlorosis virus". Plant Disease 90, n.º 6 (junho de 2006): 814–19. http://dx.doi.org/10.1094/pd-90-0814.
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Tomato chlorosis virus (ToCV), family Closteroviridae, genus Crinivirus, causes interveinal chlorosis, leaf brittleness, and limited necrotic flecking or leaf bronzing on tomato leaves. ToCV can cause a decline in plant vigor and reduce fruit yield. It is emerging as a serious production problem for field and greenhouse tomato growers, and has been increasing in prevalence in many parts of the world. The virus is unique among known whitefly-transmitted viruses, due to its ability to be transmitted by four whitefly vectors from two genera. Studies demonstrated that transmission efficiency and virus persistence in the vector varies significantly among the different whitefly vectors. Trialeurodes abutilonea and Bemisia tabaci biotype B are highly efficient vectors of ToCV. B. tabaci biotype A and T. vaporariorum are less efficient vectors, but are fully capable of transmission. ToCV persists for up to 5 days in T. abutilonea, 2 days in B. tabaci biotype B, and only 1 day in B. tabaci biotype A and T. vaporariorum. ToCV has a moderately wide host range, infecting 24 host plant species in seven families. A portion of the coat protein coding region of five geographically diverse ToCV isolates was compared and found to be highly conserved. This information, coupled with existing information on conservation within the heat shock protein 70 homologue coding region, suggests that many ToCV isolates throughout the world are related very closely, and may have been distributed on plant material.
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Gray, Stewart M., e Nanditta Banerjee. "Mechanisms of Arthropod Transmission of Plant and Animal Viruses". Microbiology and Molecular Biology Reviews 63, n.º 1 (1 de março de 1999): 128–48. http://dx.doi.org/10.1128/mmbr.63.1.128-148.1999.
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SUMMARY A majority of the plant-infecting viruses and many of the animal-infecting viruses are dependent upon arthropod vectors for transmission between hosts and/or as alternative hosts. The viruses have evolved specific associations with their vectors, and we are beginning to understand the underlying mechanisms that regulate the virus transmission process. A majority of plant viruses are carried on the cuticle lining of a vector’s mouthparts or foregut. This initially appeared to be simple mechanical contamination, but it is now known to be a biologically complex interaction between specific virus proteins and as yet unidentified vector cuticle-associated compounds. Numerous other plant viruses and the majority of animal viruses are carried within the body of the vector. These viruses have evolved specific mechanisms to enable them to be transported through multiple tissues and to evade vector defenses. In response, vector species have evolved so that not all individuals within a species are susceptible to virus infection or can serve as a competent vector. Not only are the virus components of the transmission process being identified, but also the genetic and physiological components of the vectors which determine their ability to be used successfully by the virus are being elucidated. The mechanisms of arthropod-virus associations are many and complex, but common themes are beginning to emerge which may allow the development of novel strategies to ultimately control epidemics caused by arthropod-borne viruses.
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Su, Yuanzhang, Xinfeng Guo, Hang Luo, Jingyuan Wang e Zhen Liu. "A Boundary Scan Test Vectors Optimization Method Based on Improved GA-AO* Approach Considering Fault Probability Model". Applied Sciences 14, n.º 6 (13 de março de 2024): 2410. http://dx.doi.org/10.3390/app14062410.
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The generation of test vectors is a key technique that affects the efficiency and fault detection rate of the boundary scan test. Aiming at the local optimal solution problem of the current common test vectors generation algorithm, this paper proposes a test vectors generation algorithm based on improved GA-AO* model, through which the test vectors are generated by using the idea of heuristic search and backtracking correction. In order to speed up the heuristic search, this paper designed a heuristic function with both prior and posterior parameters to describe the influence of typical faults on the failure probability index of the test vectors. At the same time, this paper used a genetic algorithm (GA) to determine the specific values of the posterior parameters iteratively. Finally, through theoretical analysis and physical verification, compared with the test vector generated by the traditional method, the test vector generated by this method is optimized on the prior failure probability index and performs better in the physical experiment.
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Habel, Marie-Eve, Mathieu Drouin e Daniel Jung. "Maintenance of Epstein–Barr virus-derived episomal vectors in the murine Sp2/0 myeloma cell line is dependent upon exogenous expression of human EBP2". Biochemistry and Cell Biology 82, n.º 3 (1 de junho de 2004): 375–80. http://dx.doi.org/10.1139/o04-037.
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Vectors carrying the origin of replication (oriP) and driving expression of the EBNA-1 protein from Epstein–Barr virus (EBV) replicate as extrachromosomal episomes in human cells. Whether these vectors can be maintained as episomes in murine cells is still controversial. Here we demonstrate that EBNA-1 expression alone was unable to maintain episomal expression of an EBV-based vector in the murine Sp2/0 cell line. However, we were able to obtain long-term episome maintenance in Sp2/0 cells after exogenously expressing human EBP2 by genetic engineering. Our results provide further evidence for the fundamental role of human EBP2 in episomal maintenance of EBV-based vectors. Moreover, we demonstrate that EBV-based vectors can be successfully used in cells presumably incompetent for episomal maintenance.Key words: EBV vector, EBNA-1, EBP2, episomal maintenance, mouse cell, Sp2/0 myeloma cell line.
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Manisha. B. Shinde, Dr. Archana D. Kajale, Dr. Madhuri A. Channawar e Dr. Shilpa R. Gawande. "Vector-mediated cancer gene therapy: A review". GSC Biological and Pharmaceutical Sciences 13, n.º 2 (30 de novembro de 2020): 152–65. http://dx.doi.org/10.30574/gscbps.2020.13.2.0368.
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Gene therapy is the transfer of genetic material to cure a disease or at least to improve the clinical status of a patient. One of the basic concepts of gene therapy is to transform viruses into genetic shuttles, which will deliver the gene of interest into the target cells. Safe methods have been devised to do this, using several viral and non-viral vectors. Two main approaches emerged: in vivo modification and ex vivo modification. Retrovirus, adenovirus, adenoassociated virus are suitable for gene therapeutic approaches which are based on permanent expression of the therapeutic gene. Non-viral vectors are far less efficient than viral vectors, but they have advantages due to their low immunogenicity and their large capacity for therapeutic DNA. The most commonly used DNA virus vectors are based on adenoviruses and adeno-associated viruses. An example of gene-knockout mediated gene therapy is the knockout of the human CCR5 gene in T-cells in order to control HIV infection. To improve the function of non-viral vectors, the addition of viral functions such as receptor mediated uptake and nuclear translocation of DNA may finally lead to the development of an artificial virus. Gene transfer protocols have been approved for human use in inherited diseases, cancers and acquired disorders. Although the available vector systems are able to deliver genes in vivo into cells, the ideal delivery vehicle has not been found. Thus, the present viral vectors should be used only with great caution in human beings and further progress in vector development is necessary.
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Gong, Qi, Bin Wang, Xubiao Lu, Jiantao Tan, Yuke Hou, Taoli Liu, Yao-Guang Liu e Qinlong Zhu. "Nicking Endonuclease-Mediated Vector Construction Strategies for Plant Gene Functional Research". Plants 9, n.º 9 (25 de agosto de 2020): 1090. http://dx.doi.org/10.3390/plants9091090.
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Plant genetic engineering vectors, such as RNA interference (RNAi) and CRISPR/Cas9 vectors, are important tools for plant functional genomics. Efficient construction of these functional vectors can facilitate the study of gene function. Although some methods for vector construction have been reported, their operations are still complicated and costly. Here, we describe a simpler and low-cost vector construction method by nicking endonucleases-mediated DNA assembly (NEMDA), which uses nicking endonucleases to generate single-strand overhanging complementary ends for rapid assembly of DNA fragments into plasmids. Using this approach, we rapidly completed the construction of four RNAi vectors and a CRISPR/Cas9 knockout vector with five single-guide RNA (sgRNA)-expression cassettes for multiplex genome editing, and successfully achieved the goal of decreasing the expression of the target genes and knocking out the target genes at the same time in rice. These results indicate the great potential of NEMDA in assembling DNA fragments and constructing plasmids for molecular biology and functional genomics.
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Lindemann, Dirk, e Hans Schnittler. "Genetic manipulation of endothelial cells by viral vectors". Thrombosis and Haemostasis 102, n.º 12 (2009): 1135–43. http://dx.doi.org/10.1160/th09-10-0724.
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SummaryThe need for uncovering molecular mechanisms in endothelial cell biology has tremendously increased in the last decades as it became more and more clear that the endothelium is an important target in nearly all diseases and treatments (drug delivery) and plays a central role in regeneration processes. One of the critical methods generally applied in cell biology research to uncover structural and functional aspects is the modulation of protein expression by over-expression, expression of mutant variants or gene silencing. This strategy, however, requires genetic manipulation of the respective cells. The classical gene transfer by chemical transfection techniques works pretty well in a large variety of cultured cells but fails for most endothelial cell types. Insufficient transfection rates and gene expression levels as well as the sensitivity of the endothelium against chemical transfection reagents limits utilisation of this technique for endothelial cell biology research. This holds true not only for primary endothelial cell cultures and endothelial cells in vivo but also for endothelial cell lines, e.g. endothelioma cells. The development of viral vectors originally designed for gene therapy approaches has significantly improved the methodological spectrum in endothelial cell research. Two viral vector systems, based on retroviruses and adenoviruses, deliver transgenic information highly efficient into both cultured endothelial cells and in endothelial cells in vivo, respectively. This review aims to give a comprehensive overview of these two vector systems that appear to be reliable and efficient tools for gene delivery into endothelial cell types.
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Whitacre, David C., Farah Hedjran, Ingo Schmidt-Wolf, Charles Prussak, Tony Reid, Thomas J. Kipps e David Whitacre. "Highly Efficient Gene-Transfer into Chronic Lymphocytic Leukemia Cells Using Adenovirus Type 35 Genetic Vectors." Blood 106, n.º 11 (16 de novembro de 2005): 2109. http://dx.doi.org/10.1182/blood.v106.11.2109.2109.
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Abstract Adenovirus (Ad) vectors have been used to introduce genetic material into mammalian cells for gene-expression studies and/or gene therapy. Ad serotypes 2 and 5, the most widely used Ad virus vectors, belong to the group C adenoviruses, which bind to the coxsakie/adenovirus receptor (CAR) present on cells that are most susceptible to virus infection. Because lymphoid cells generally do not express CAR, high-titer virus and optimal conditions are required to infect lymphocytes, including the neoplastic cells of most lymphoid malignancies. Ad35, on the other hand, is a member of the group B adenoviruses that infect cells by binding CD46, a receptor expressed on most cell types. We found chronic lymphocytic leukemia B cells (n = 10) expressed high-levels of CD46 by flow cytometry, whereas none of the CLL samples expressed CAR by immunoblot analyses. We examined and compared the relative susceptibility of CLL cells to infection by Ad5 versus Ad35 vectors at various multiplicity of infection (MOI). These studies revealed that CLL cells were 100-fold more sensitive to infection with Ad35 than with Ad5. To examine whether this improved tropism of Ad35 for CLL cells was due to the adenovirus receptor for CD46, we examined the relative susceptibility of CLL cells to infection by Ad5 vectors that had been engineered to express the Ad35 knob fiber protein (Shayakhmetov DM, et al., J Virol 2000, vol 74, pp. 2567-83) responsible for binding CD46, designated Ad5F35. Titration studies evaluating for expression of a reporter transgene in infected CLL cells (e.g. the gene encoding green fluorescence protein (GFP)), found that Ad5F35 vectors also were > 100-fold more effective than Ad5 vectors at transducing CLL B cells. These studies reveal that Ad5F35 is a highly efficient vector for transducing CLL cells, a quality that should make these vectors better suited than Ad5 virus vectors for studies requiring gene transfer and/or gene therapy of this and related lymphoid malignancies.