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Artykuły w czasopismach na temat "Dengue virus genome replication"
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Alcaraz-Estrada, Sofia Lizeth, Martha Yocupicio-Monroy i Rosa María del Angel. "Insights into dengue virus genome replication". Future Virology 5, nr 5 (wrzesień 2010): 575–92. http://dx.doi.org/10.2217/fvl.10.49.
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Wang, Kezhen, Juanjuan Wang, Ta Sun, Gang Bian, Wen Pan, Tingting Feng, Penghua Wang, Yunsen Li i Jianfeng Dai. "Glycosphingolipid GM3 is Indispensable for Dengue Virus Genome Replication". International Journal of Biological Sciences 12, nr 7 (2016): 872–83. http://dx.doi.org/10.7150/ijbs.15641.
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Alvarez, Diego E., María F. Lodeiro, Silvio J. Ludueña, Lía I. Pietrasanta i Andrea V. Gamarnik. "Long-Range RNA-RNA Interactions Circularize the Dengue Virus Genome". Journal of Virology 79, nr 11 (1.06.2005): 6631–43. http://dx.doi.org/10.1128/jvi.79.11.6631-6643.2005.
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ABSTRACT Secondary and tertiary RNA structures present in viral RNA genomes play essential regulatory roles during translation, RNA replication, and assembly of new viral particles. In the case of flaviviruses, RNA-RNA interactions between the 5′ and 3′ ends of the genome have been proposed to be required for RNA replication. We found that two RNA elements present at the ends of the dengue virus genome interact in vitro with high affinity. Visualization of individual molecules by atomic force microscopy reveled that physical interaction between these RNA elements results in cyclization of the viral RNA. Using RNA binding assays, we found that the putative cyclization sequences, known as 5′ and 3′ CS, present in all mosquito-borne flaviviruses, were necessary but not sufficient for RNA-RNA interaction. Additional sequences present at the 5′ and 3′ untranslated regions of the viral RNA were also required for RNA-RNA complex formation. We named these sequences 5′ and 3′ UAR (upstream AUG region). In order to investigate the functional role of 5′-3′ UAR complementarity, these sequences were mutated either separately, to destroy base pairing, or simultaneously, to restore complementarity in the context of full-length dengue virus RNA. Nonviable viruses were recovered after transfection of dengue virus RNA carrying mutations either at the 5′ or 3′ UAR, while the RNA containing the compensatory mutations was able to replicate. Since sequence complementarity between the ends of the genome is required for dengue virus viability, we propose that cyclization of the RNA is a required conformation for viral replication.
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Yamamoto, Kristie A., Kevin Blackburn, Michael B. Goshe, Dennis T. Brown, Edimilson Migoswski, Isabele B. Campanhon, Monica F. Moreira, Davis F. Ferreira i Marcia R. Soares. "Tizoxanide Antiviral Activity on Dengue Virus Replication". Viruses 15, nr 3 (7.03.2023): 696. http://dx.doi.org/10.3390/v15030696.
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Dengue virus is an important circulating arbovirus in Brazil responsible for high morbidity and mortality worldwide, representing a huge economic and social burden, in addition to affecting public health. In this study, the biological activity, toxicity, and antiviral activity against dengue virus type 2 (DENV-2) of tizoxanide (TIZ) was evaluated in Vero cell culture. TIZ has a broad spectrum of action in inhibiting different pathogens, including bacteria, protozoa, and viruses. Cells were infected for 1 h with DENV-2 and then treated for 24 h with different concentrations of the drug. The quantification of viral production indicated the antiviral activity of TIZ. The protein profiles in infected Vero cells treated and not treated with TIZ were analyzed using the label-free quantitative proteomic approach. TIZ was able to inhibit virus replication mainly intracellularly after DENV-2 penetration and before the complete replication of the viral genome. Additionally, the study of the protein profile of infected not-treated and infected-treated Vero cells showed that TIZ interferes with cellular processes such as intracellular trafficking and vesicle-mediated transport and post-translational modifications when added after infection. Our results also point to the activation of immune response genes that would eventually lead to a decrease of DENV-2 production. TIZ is a promising therapeutic molecule for the treatment of DENV-2 infections.
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Leitmeyer, Katrin C., David W. Vaughn, Douglas M. Watts, Rosalba Salas, Iris Villalobos, de Chacon, Celso Ramos i Rebeca Rico-Hesse. "Dengue Virus Structural Differences That Correlate with Pathogenesis". Journal of Virology 73, nr 6 (1.06.1999): 4738–47. http://dx.doi.org/10.1128/jvi.73.6.4738-4747.1999.
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ABSTRACT The understanding of dengue virus pathogenesis has been hampered by the lack of in vitro and in vivo models of disease. The study of viral factors involved in the production of severe dengue, dengue hemorrhagic fever (DHF), versus the more common dengue fever (DF), have been limited to indirect clinical and epidemiologic associations. In an effort to identify viral determinants of DHF, we have developed a method for comparing dengue type 2 genomes (reverse transcriptase PCR in six fragments) directly from patient plasma. Samples for comparison were selected from two previously described dengue type 2 genotypes which had been shown to be the cause of DF or DHF. When full genome sequences of 11 dengue viruses were analyzed, several structural differences were seen consistently between those associated with DF only and those with the potential to cause DHF: a total of six encoded amino acid charge differences were seen in the prM, E, NS4b, and NS5 genes, while sequence differences observed within the 5′ nontranslated region (NTR) and 3′ NTR were predicted to change RNA secondary structures. We hypothesize that the primary determinants of DHF reside in (i) amino acid 390 of the E protein, which purportedly alters virion binding to host cells; (ii) in the downstream loop (nucleotides 68 to 80) of the 5′ NTR, which may be involved in translation initiation; and (iii) in the upstream 300 nucleotides of the 3′ NTR, which may regulate viral replication via the formation of replicative intermediates. The significance of four amino acid differences in the nonstructural proteins NS4b and NS5, a presumed transport protein and the viral RNA polymerase, respectively, remains unknown. This new approach to the study of dengue virus genome differences should better reflect the true composition of viral RNA populations in the natural host and permit their association with pathogenesis.
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Dethoff, Elizabeth A., Mark A. Boerneke, Nandan S. Gokhale, Brejnev M. Muhire, Darren P. Martin, Matthew T. Sacco, Michael J. McFadden i in. "Pervasive tertiary structure in the dengue virus RNA genome". Proceedings of the National Academy of Sciences 115, nr 45 (19.10.2018): 11513–18. http://dx.doi.org/10.1073/pnas.1716689115.
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RNA virus genomes are efficient and compact carriers of biological information, encoding information required for replication both in their primary sequences and in higher-order RNA structures. However, the ubiquity of RNA elements with higher-order folds—in which helices pack together to form complex 3D structures—and the extent to which these elements affect viral fitness are largely unknown. Here we used single-molecule correlated chemical probing to define secondary and tertiary structures across the RNA genome of dengue virus serotype 2 (DENV2). Higher-order RNA structures are pervasive and involve more than one-third of nucleotides in the DENV2 genomic RNA. These 3D structures promote a compact overall architecture and contribute to viral fitness. Disrupting RNA regions with higher-order structures leads to stable, nonreverting mutants and could guide the development of vaccines based on attenuated RNA viruses. The existence of extensive regions of functional RNA elements with tertiary folds in viral RNAs, and likely many other messenger and noncoding RNAs, means that there are significant regions with pocket-containing surfaces that may serve as novel RNA-directed drug targets.
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Asyura, Muhammad Mikail Athif Zhafir, Ahmad Fauzi i Fakhru Adlan Ayub. "Potential of Peptide-Based Non-Structural Protein 1 (NS1) Inhibitor in Obstructing Dengue Virus (DENV) Replication". Green Medical Journal 3, nr 1 (29.04.2021): 1–12. http://dx.doi.org/10.33096/gmj.v3i1.71.
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Introduction: Dengue Virus (DENV) is the pathogen for human dengue fever and is responsible for 390 million infections per year. The viral genome produces about 10 viral protein products, one of them being NS1. The NS1 protein plays a key role in viral replication and stimulation of humoral immune cells, thus being the perfect candidate to create an effective antiviral drug or vaccine for dengue
Methods: Dengue Virus (DENV) is the pathogen for human dengue fever and is responsible for 390 million infections per year. The viral genome produces about 10 viral protein products, one of them being NS1. The NS1 protein plays a key role in viral replication and stimulation of humoral immune cells, thus being the perfect candidate to create an effective antiviral drug or vaccine for dengue
Conclusion: The review established promising results of using peptide-based intervention on NS1. Further in vivo and randomized controlled trials are advised to solidify the applicability and biosafety of the intervention
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Yang, Siwy Ling, Riccardo Delli Ponti, Yue Wan i Roland G. Huber. "Computational and Experimental Approaches to Study the RNA Secondary Structures of RNA Viruses". Viruses 14, nr 8 (16.08.2022): 1795. http://dx.doi.org/10.3390/v14081795.
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Most pandemics of recent decades can be traced to RNA viruses, including HIV, SARS, influenza, dengue, Zika, and SARS-CoV-2. These RNA viruses impose considerable social and economic burdens on our society, resulting in a high number of deaths and high treatment costs. As these RNA viruses utilize an RNA genome, which is important for different stages of the viral life cycle, including replication, translation, and packaging, studying how the genome folds is important to understand virus function. In this review, we summarize recent advances in computational and high-throughput RNA structure-mapping approaches and their use in understanding structures within RNA virus genomes. In particular, we focus on the genome structures of the dengue, Zika, and SARS-CoV-2 viruses due to recent significant outbreaks of these viruses around the world.
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Markoff, Lewis, Xiaou Pang, Huo-shu Houng, Barry Falgout, Raymond Olsen, Estella Jones i Stephanie Polo. "Derivation and Characterization of a Dengue Type 1 Host Range-Restricted Mutant Virus That Is Attenuated and Highly Immunogenic in Monkeys". Journal of Virology 76, nr 7 (1.04.2002): 3318–28. http://dx.doi.org/10.1128/jvi.76.7.3318-3328.2002.
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ABSTRACT We recently described the derivation of a dengue serotype 2 virus (DEN2mutF) that exhibited a host range-restricted phenotype; it was severely impaired for replication in cultured mosquito cells (C6/36 cells). DEN2mutF virus had selected mutations in genomic sequences predicted to form a 3′ stem-loop structure (3′-SL) that is conserved among all flavivirus species. The 3′-SL constitutes the downstream terminal ∼95 nucleotides of the 3′ noncoding region in flavivirus RNA. Here we report the introduction of these same mutational changes into the analogous region of an infectious DNA derived from the genome of a human-virulent dengue serotype 1 virus (DEN1), strain Western Pacific (DEN1WP). The resulting DEN1 mutant (DEN1mutF) exhibited a host range-restricted phenotype similar to that of DEN2mutF virus. DEN1mutF virus was attenuated in a monkey model for dengue infection in which viremia is taken as a correlate of human virulence. In spite of the markedly reduced levels of viremia that it induced in monkeys compared to DEN1WP, DEN1mutF was highly immunogenic. In addition, DEN1mutF-immunized monkeys retained high levels of neutralizing antibodies in serum and were protected from challenge with high doses of the DEN1WP parent for as long as 17 months after the single immunizing dose. Phenotypic revertants of DEN1mutF and DEN2mutF were each detected after a total of 24 days in C6/36 cell cultures. Complete nucleotide sequence analysis of DEN1mutF RNA and that of a revertant virus, DEN1mutFRev, revealed that (i) the DEN1mutF genome contained no additional mutations upstream from the 3′-SL compared to the DEN1WP parent genome and (ii) the DEN1mutFRev genome contained de novo mutations, consistent with our previous hypothesis that the defect in DEN2mutF replication in C6/36 cells was at the level of RNA replication. A strategy for the development of a tetravalent dengue vaccine is discussed.
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Sanford, Thomas J., Harriet V. Mears, Teodoro Fajardo, Nicolas Locker i Trevor R. Sweeney. "Circularization of flavivirus genomic RNA inhibits de novo translation initiation". Nucleic Acids Research 47, nr 18 (8.08.2019): 9789–802. http://dx.doi.org/10.1093/nar/gkz686.
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Abstract Members of the Flaviviridae family, including dengue virus (DENV) and yellow fever virus, cause serious disease in humans, whilst maternal infection with Zika virus (ZIKV) can induce microcephaly in newborns. Following infection, flaviviral RNA genomes are translated to produce the viral replication machinery but must then serve as a template for the transcription of new genomes. However, the ribosome and viral polymerase proceed in opposite directions along the RNA, risking collisions and abortive replication. Whilst generally linear, flavivirus genomes can adopt a circular conformation facilitated by long-range RNA–RNA interactions, shown to be essential for replication. Using an in vitro reconstitution approach, we demonstrate that circularization inhibits de novo translation initiation on ZIKV and DENV RNA, whilst the linear conformation is translation-competent. Our results provide a mechanism to clear the viral RNA of ribosomes in order to promote efficient replication and, therefore, define opposing roles for linear and circular conformations of the flavivirus genome.
Rozprawy doktorskie na temat "Dengue virus genome replication"
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Branfield, Lauren Elizabeth. "Structural and biochemical analysis of protein/RNA interactions during the initiation of dengue virus genome replication". Thesis, University of Leeds, 2018. http://etheses.whiterose.ac.uk/21365/.
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Williams, Kelley J. "Silver Nanoparticles Inhibit the Binding and Replication of Dengue Virus". Wright State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=wright1431880664.
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Trist, Iuni Margaret Laura. "In silico design of novel inhibitors of dengue virus replication". Thesis, Cardiff University, 2014. http://orca.cf.ac.uk/71338/.
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Dengue virus (DENV) is a health burden responsible of 50-100 million new cases and 22,000 deaths per year and its four serotypes are worryingly spreading out of the endemic regions. Current therapy is symptomatic, making antiviral research on DENV an unmet need. Vaccine development is more challenging than expected, so the development of anti-DENV drugs is particularly important for infection management. DENV is a positive sense single stranded RNA virus that replicates within cells exploiting both host and viral enzymes to replicate. Based on the hypothesis that DENV infection can be stopped with the inhibition of one or more of the enzymes that are fundamental for its replication, the aims of the studies reported in this PhD thesis were to: identify novel targets to combat DENV infection, generate new basic knowledge and discover potential novel chemical leads exploiting those targets. Novel approaches combining molecular modelling techniques, classical Medicinal Chemistry approaches, chemical synthesis and in& vitro assays were applied to four essential viral-encoded proteins: the capsid (C), the NS3 NTPase/helicase (NS3hel), the NS5 methyltransferase (NS5 MTase) and the NS5 RNA-dependent RNA polymerase (NS5 RdRp). Novel understanding of the 3'-5' translocation mechanism of NS3hel along the RNA has been hypothesised, increasing awareness about DENV-encoded proteins. Important knowledge on the mode of action of promising antiviral compounds has been acquired, for example that ST-148 stabilises C protein-protein interactions and that published N-sulphonylanthranilic acid RdRp inhibitors bind to a unique allosteric site. Novel promising DENV inhibitor scaffolds have also been developed and the chemical synthesis of one of them has been described, showing that the adopted drug discovery approaches are suitable starting points for the development of anti-DENV medicines. The results obtained represent a significant contribution to DENV research in increasing basic knowledge and in identifying good chemical leads for future work.
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Tran, Tuan Anh. "Screening against the dengue virus polymerase". Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4006.
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La dengue, une des maladies les plus largement émergents actuellement, avec 390 millions d'infections chaque année (OMS), est causée par le virus de la dengue contre lequel il n’existe pas de traitements. La protéine NS5 a un rôle important dans le cycle de réplication. Cette protéine se compose d'une méthionine S-transférase d’adénosyl en N-terminal et une ARN polymérase dépendante de l'ARN (RdRp) en C-terminal. Cette NS5 RdRp peut catalyser non seulement la synthèse du brin négatif de l'ARN, utilisé comme matrice pour synthétiser l'ARN brin plus-supplémentaire, mais aussi pour la synthèse d'un ARN complémentaire à partir d'une matrice court e d'ARN sans amorce (de novo). Dans ce travail de thèse, nous présentons la production et le test de l'activité de la protéine NS5, ainsi que du domaine polymérase RdRp pour les quatre sérotypes du virus de la dengue en développant un nouveau test enzymatique, en utilisant comme un réactif fluorescent. L'utilisation de ce réactif fluorescent a également contribué à la détermination des conditions optimisées pour développer un essai de criblage de l'activité polymérase pour identifier des inhibiteurs contre le virus de la dengue. En outre, quatre flavonoïdes, Hinokiflavone, apigénine, la quercétine et Amentoflavone ont montré des valeurs d’IC50 équivalentes contre toutes les constructions NS5 et les domaines polymérase des quatre sérotypesDengue fever, one of the most widely emerging diseases nowadays with 390 million infections each year (WHO), is caused by Dengue virus in which no official antiviral reagent or vaccine is available. The NS5 protein has an important role in the replication cycle. This protein consists of a S-adenosyl methionine transferase at N-terminal and a RNA dependent RNA polymerase (RdRp) at C-terminal. This NS5 RdRp can catalyse for not only synthesis of minus-strand RNA to be used as the template to synthesize additional plus-strand RNA but also synthesizing a complement RNA from a short RNA template without primer (de novo). In this research we present the production and activity test for NS5 protein and N-terminal extended sequence 266-900 from NS5 RdRp of all first four serotypes of Dengue virus and a construct of sequence 273-900 using a new enzymatic assay, using Picogreen as fluorescent reagent. Using this fluorescent reagent also helped determining the optimised conditions to develop a screening assay for inhibitors against dengue polymerase activity. In addition, four flavonoids, Hinokiflavone, Apigenin, Quercetin and Amentoflavone showed approximate IC50 values when testing on all NS5 and polymerase protein constructs of all four serotypes
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Deng, Ruitang. "Molecular cloning, nucleotide sequencing and genome replication of bovine viral diarrhea virus /". The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487779914825349.
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Yousuf, Amjad. "High-throughput quantitative proteomic analysis of host proteins interacting with dengue virus replication complex". Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.702423.
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Dengue virus (DENV) is a global health problem with approximately 390 million infections annually. Currently, no completely effective vaccines or medications are available to prevent DENV infection. This study used high-throughput quantitative proteomic analysis to identify cellular proteins that modulate DENV replication and are potential targets for the development of antiviral strategies. DENV is known to replicate and package its genome in association with perinuclear ER membranes. Initially, experimental conditions were optimised to infect human Huh-7 liver cells at high efficiency, with DENV serotypes -2 and -4 and to isolate a subcellular heavy membrane fraction (16K) enriched in the DENV replication complex. Then, stable isotope labelling by amino acids in cell culture (SILAC) coupled with high-throughput mass spectrometry (MS) was used to identify changes in the Huh-7 cell proteome and the subcellular 16K fraction in response to DENV-2 and DENV-4 infection. The analysis led to the identification and quantification of 3650 and 4026 and 3461 and 3668 proteins in the 16K and total cell proteomes from DENV-2 and DENV-4 infected cells respectively. For comparison, the total cell proteomes were also analysed by tandem mass tagging combined with MS. Proteomic bioinformatics was done on the datasets which showed that DENV modulated various cellular pathways including; protein biosynthesis, the secretory pathway, lipid metabolism and the cell cycle. A comparison of changes in the total and 16K proteomes from DENV infected cells identified a number of cellular proteins that selectively increased in the replicase containing fraction. which was validated by Western blotting and immunofluorescence analysis. Seven proteins (APOB, ARFRP1, BAG2, GOLGA1, GOLGB1, GOSRI and TMED9) were further investigated for their role in DENV -2 replication by examining either viral or replicon replication in cells depleted of the proteins by siRNA knockdown which revealed proteins that both positively and negatively modulated DENV replication.
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Beeharry, Yasnee. "Role of RNA Genome Structure and Paraspeckle Proteins In Hepatitis Delta Virus Replication". Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/35343.
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The Hepatitis Delta Virus (HDV) is an RNA pathogen that uses the host DNA-dependent RNA polymerase II (RNAP II) to replicate. Previous studies identified the right terminal domain of genomic polarity (R199G) of HDV RNA as an RNAP II promoter, but the features required for HDV RNA to be used as an RNA promoter were unknown. In order to identify the structural features of an HDV RNA promoter, I analyzed 473,139 sequences representing 2,351 new R199G variants generated by high-throughput sequencing of a viral population replicating in 293 cells. To complement this analysis, I also analyzed the same region from HDV sequences isolated from various hosts. Base pair covariation analysis indicates a strong
selection for the rod-like conformation. Several selected RNA motifs were identified,
including a GC-rich stem, a CUC/GAG motif and a uridine at the initiation site of
transcription. In addition, a polarization of purine/pyrimidine content was identified, which might represent a motif favourable for the binding of the host Polypyrimidine tract-binding protein-associated-splicing-factor (PSF), p54 and Paraspeckle Protein 1 (PSP1). Previously, it was shown that R199G binds both RNAP II and PSF, that PSF increased the HDV levels during in vitro transcription and that p54 binds R199G. In the present study, I showed that PSP1 also associates with HDV RNA and I investigated whether these proteins are required for HDV replication. My results show that knockdown of PSF, p54 and PSP1 resulted in a decrease of HDV accumulation. These proteins are highly concentrated in paraspeckles, which are nuclear structures involved in storage of transcripts generated by RNAP II. I found that upon viral replication in 293 cells, PSP1 appeared as bigger foci present outside of the
nucleus, while PSF and p54 foci remained in the nucleus. NEAT1 is a long non-coding RNA essential for the formation of paraspeckles. Upon HDV replication, I found an increase of the intensity and size of NEAT1 foci that correlates with an increase of NEAT1 transcripts. Altogether, these data suggest that HDV replication results in an alteration of the paraspeckles structures, providing foundation for further investigation of the paraspeckles role in HDV cycle. Overall, the present study addresses the importance of the HDV RNA structure and of the host paraspeckle proteins for HDV replication.
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Stirrups, Kathleen Elizabeth. "A defective-RNA expression vector for targeted recombination of the coronavirus infectious bronchitis virus". Thesis, University of Reading, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285965.
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Hellen, C. U. T. "Studies on the structure, replication and expression of the cherry leaf roll virus genome". Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305712.
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Mullin, Anne Elizabeth. "Factors affecting the balance between transcription and replication of the influenza A virus genome". Thesis, University of Cambridge, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.615957.
Pełny tekst źródłaKsiążki na temat "Dengue virus genome replication"
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Viral genome replication. New York, NY: Springer, 2009.
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Norwich), John Innes Symposium (7th 1986. Virus replication and genome interaction: Proceedings of the seventh John Innes Symposium. Cambridge: Company of Biologists, 1987.
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John, Innes Symposium (7th 1986 Norwich England). Virus replication and genome interactions: Proceedings of the seventh John Innes Symposium, Norwich, 1986. Cambridge: Company of Biologists, 1987.
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K, Wagner Edward, i Wagner Edward K, red. Basic virology. Wyd. 3. Malden, MA: Blackwell Pub., 2008.
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1963-, Feng Zhi, i Long Ming, red. Viral genomes: Diversity, properties, and parameters. Hauppauge, NY: Nova Science Publishers, 2009.
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Principles of molecular virology. London: Academic Press, 1993.
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Principles of molecular virology. Wyd. 4. Amsterdam: Elsevier Academic Press, 2005.
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Principles of molecular virology. Wyd. 2. San Diego: Academic Press, 1997.
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Principles of molecular virology. Wyd. 4. Amsterdam: Elsevier Academic Press, 2005.
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Virus Replication and Genome Interaction. The Company of Biologists Limited, 1987.
Znajdź pełny tekst źródłaCzęści książek na temat "Dengue virus genome replication"
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Ferrer-Orta, Cristina, i Nuria Verdaguer. "RNA Virus Polymerases". W Viral Genome Replication, 383–401. Boston, MA: Springer US, 2009. http://dx.doi.org/10.1007/b135974_18.
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Aw, Pauline Poh Kim, Paola Florez de Sessions, Andreas Wilm, Long Truong Hoang, Niranjan Nagarajan, October M. Sessions i Martin Lloyd Hibberd. "Next-Generation Whole Genome Sequencing of Dengue Virus". W Dengue, 175–95. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-0348-1_12.
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Wendeler, Michaela, Jennifer T. Miller i Stuart F. J. Le Grice. "Human Immunodeficiency Virus Reverse Transcriptase". W Viral Genome Replication, 403–27. Boston, MA: Springer US, 2009. http://dx.doi.org/10.1007/b135974_19.
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Lindenbach, Brett D., i Timothy L. Tellinghuisen. "Hepatitis C Virus Genome Replication". W Viral Genome Replication, 61–88. Boston, MA: Springer US, 2009. http://dx.doi.org/10.1007/b135974_4.
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Yi, Guanghui, i C. Cheng Kao. "Brome Mosaic Virus RNA Replication and Transcription". W Viral Genome Replication, 89–108. Boston, MA: Springer US, 2009. http://dx.doi.org/10.1007/b135974_5.
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Liu, Shenping, i Fred L. Homa. "Atomic Structure of the Herpes Simplex Virus 1 DNA Polymerase". W Viral Genome Replication, 365–81. Boston, MA: Springer US, 2009. http://dx.doi.org/10.1007/b135974_17.
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Paranjape, Suman M., i Eva Harris. "Control of Dengue Virus Translation and Replication". W Current Topics in Microbiology and Immunology, 15–34. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-02215-9_2.
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Krug, Robert M., i Ervin Fodor. "The virus genome and its replication". W Textbook of Influenza, 57–66. Oxford, UK: John Wiley & Sons, Ltd, 2013. http://dx.doi.org/10.1002/9781118636817.ch4.
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Krug, Robert M., Firelli V. Alonso-Caplen, Ilkka Julkunen i Michael G. Katze. "Expression and Replication of the Influenza Virus Genome". W The Influenza Viruses, 89–152. Boston, MA: Springer US, 1989. http://dx.doi.org/10.1007/978-1-4613-0811-9_2.
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Weller, Sandra K. "Herpes Simplex Virus DNA Replication and Genome Maturation". W The DNA Provirus, 189–213. Washington, DC, USA: ASM Press, 2014. http://dx.doi.org/10.1128/9781555818302.ch14.
Pełny tekst źródłaStreszczenia konferencji na temat "Dengue virus genome replication"
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Davi, Caio, André Pastor, Thiego Oliveira, Fernando B. Lima Neto, Ulisses Braga-Neto, Abigail W. Bigham, Michael Bamshad, Ernesto T. A. Marques i Bartolomeu Acioli-Santos. "Computational Intelligence applied to Human Genome Data for the Dengue Severity Prognosis". W XI Simpósio Brasileiro de Bioinformática. Sociedade Brasileira de Computação - SBC, 2019. http://dx.doi.org/10.5753/bsb_estendido.2018.8800.
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Dengue has become one of the most important worldwide arthropodborne diseases around the world. Here, one hundred and two Brazilian dengue virus (DENV) III patients and controls were genotyped for 322 innate immunity gene loci. All biological data (including age, sex and genome background) were analyzed using Machine Learning techniques to discriminate tendency to severe dengue phenotype development. Our current approach produces median values for accuracy greater than 86%, with sensitivity and specificity over 98% and 51%, respectively. Genome data information from 13 key immune polymorphic SNPs was used under different dominant or recessive models. Our approach is a valuable tool for early diagnosis of the severe form of dengue infection and can be used to identify individuals at high risk of developing this form of the disease even in uninfected individuals. The model also identifies various genes involved dengue severity.
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Li, Chi-Chuan. "Enhancement of dengue virus replication in transgenic mosquitoesAedes aegyptiexpressing anti-thioester containing protein 1 (TEP1) microRNA". W 2016 International Congress of Entomology. Entomological Society of America, 2016. http://dx.doi.org/10.1603/ice.2016.115686.
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Mahapatro, Pushpa Susant, i Jatinderkumar R. Saini. "An Innovative Computer Programming based Analysis of Zika Virus for Identification of Genome Replication Location". W 2021 2nd Global Conference for Advancement in Technology (GCAT). IEEE, 2021. http://dx.doi.org/10.1109/gcat52182.2021.9587478.
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Elbashir, Israa, Heba Al Khatib i Hadi Yassine. "Replication Dynamics, Pathogenicity, and Evolution of Influenza Viruses in Intestinal Caco-2 Cells". W Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0166.
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Background: Influenza virus is a major cause of respiratory infections worldwide. Besides the common respiratory symptoms, namouras cases with gastrointestinal symptoms have been reported. Moreover, influenza virus has been detected in feces of up to 20.6 % of influenza-infected patients. Therefore, direct infection of intestinal cells with influenza virus is suspected; however, the mechanism of this infection has not been explored. AIM: To investigate influenza virus replication, cellular responses to infection, and virus evolution following serial infection in human Caucasian colon adenocarcinoma cells (Caco-2 cells). Method: Two influenza A subtypes (A/H3N2 and A/H1N1pdm 09) and one influenza B virus (B/Yamagata) were serially passaged in Caco-2. Quantitative PCR was used to study hormones and cytokines expression following infection. Deep sequencing analysis of viral genome was used to assess the virus evolution. Results: The replication capacity of the three viruses was maintained throughout 12 passages, with H3N2 virus being the fastest in adaptation. The expression of hormone and cytokines in Caco-2 cells was considerably different between the viruses and among the passages, however, a pattern of induction was observed at the late phase of infection. Deep sequencing analysis revealed a few amino acid substitutions in the HA protein of H3N2 and H1N1 viruses, mostly in the antigenic site. Moreover, virus evolution at the quasispecies level based on HA protein revealed that H3N2 and H1N1 harbored more diverse virus populations when compared to IBV, indicating their higher evolution within Caco-2 cells. Conclusion: The findings of this study indicate the possibility of influenza virus replication in intestinal cells. To further explain the gastrointestinal complications of influenza infections in-vivo experiments with different influenza viruses are needed.
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Yusuf, Amry Irsyada, Beti Ernawati Dewi i Fithriyah Sjatha. "Antiviral Activity of Cynometra ramiflora Linn Leaves Extract Against Replication of Dengue Virus Serotype 2 on Huh 7.5 Cell In Vitro". W Bromo Conference, Symposium on Natural Products and Biodiversity. SCITEPRESS - Science and Technology Publications, 2018. http://dx.doi.org/10.5220/0008359901980201.
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Kaptelova, V. V., A. S. Speranskaya, A. E. Samoilov, A. V. Valdokhina, V. P. Bulanenko, E. V. Korneenko, O. Y. Shipulina i V. G. Akimkin. "MUTATIONS IN THE GENOMES OF SARS-COV-2 FROM CLINICAL SAMPLES OBTAINED IN LATE MARCH-EARLY APRIL FROM PATIENTS IN MOSCOW". W Molecular Diagnostics and Biosafety. Federal Budget Institute of Science 'Central Research Institute for Epidemiology', 2020. http://dx.doi.org/10.36233/978-5-9900432-9-9-147.
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Many papers suggested that D614G mutation in the viral spike (S) protein SARS-CoV-2 can influence the ability of virus transmission. In recent work [1], it was shown D614G influences the rate of disease transmission only in combination with the P323L mutation in the viral polymerase. We have sequenced 28 full genomes of SARS-CoV-2, obtained from clinical material from patients of different ages. The analyzed isolates belong to clades B.1 (GH) and B1.1 (GR). Combinations of mutations P323L and D614G were found in all genomes. These differences can be explained by sampling: the samples for the sequencing of the whole genome were selected with high viral load, it can be related to the rate of viral replication in intra-host. That, in turn, can be dependent on the presence of P323L/D614G mutations in the virus genome.
Raporty organizacyjne na temat "Dengue virus genome replication"
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Padmanabhan, Radha K. Structure and Functional Studies on Dengue-2 Virus Genome. Fort Belvoir, VA: Defense Technical Information Center, marzec 1986. http://dx.doi.org/10.21236/ada199075.
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Bar-Joseph, Moshe, William O. Dawson i Munir Mawassi. Role of Defective RNAs in Citrus Tristeza Virus Diseases. United States Department of Agriculture, wrzesień 2000. http://dx.doi.org/10.32747/2000.7575279.bard.
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This program focused on citrus tristeza virus (CTV), the largest and one of the most complex RNA-plant-viruses. The economic importance of this virus to the US and Israeli citrus industries, its uniqueness among RNA viruses and the possibility to tame the virus and eventually turn it into a useful tool for the protection and genetic improvement of citrus trees justify these continued efforts. Although the overall goal of this project was to study the role(s) of CTV associated defective (d)-RNAs in CTV-induced diseases, considerable research efforts had to be devoted to the engineering of the helper virus which provides the machinery to allow dRNA replication. Considerable progress was made through three main lines of complementary studies. For the first time, the generation of an engineered CTV genetic system that is capable of infecting citrus plants with in vitro modified virus was achieved. Considering that this RNA virus consists of a 20 kb genome, much larger than any other previously developed similar genetic system, completing this goal was an extremely difficult task that was accomplished by the effective collaboration and complementarity of both partners. Other full-length genomic CTV isolates were sequenced and populations examined, resulting in a new level of understanding of population complexities and dynamics in the US and Israel. In addition, this project has now considerably advanced our understanding and ability to manipulate dRNAs, a new class of genetic elements of closteroviruses, which were first found in the Israeli VT isolate and later shown to be omnipresent in CTV populations. We have characterized additional natural dRNAs and have shown that production of subgenomic mRNAs can be involved in the generation of dRNAs. We have molecularly cloned natural dRNAs and directly inoculated citrus plants with 35S-cDNA constructs and have shown that specific dRNAs are correlated with specific disease symptoms. Systems to examine dRNA replication in protoplasts were developed and the requirements for dRNA replication were defined. Several artificial dRNAs that replicate efficiently with a helper virus were created from infectious full-genomic cDNAs. Elements that allow the specific replication of dRNAs by heterologous helper viruses also were defined. The T36-derived dRNAs were replicated efficiently by a range of different wild CTV isolates and hybrid dRNAs with heterologous termini are efficiently replicated with T36 as helper. In addition we found: 1) All CTV genes except of the p6 gene product from the conserved signature block of the Closteroviridae are obligate for assembly, infectivity, and serial protoplast passage; 2) The p20 protein is a major component of the amorphous inclusion bodies of infected cells; and 3) Novel 5'-Co-terminal RNAs in CTV infected cells were characterized. These results have considerably advanced our basic understanding of the molecular biology of CTV and CTV-dRNAs and form the platform for the future manipulation of this complicated virus. As a result of these developments, the way is now open to turn constructs of this viral plant pathogen into new tools for protecting citrus against severe CTV terms and development of virus-based expression vectors for other citrus improvement needs. In conclusion, this research program has accomplished two main interconnected missions, the collection of basic information on the molecular and biological characteristics of the virus and its associated dRNAs toward development of management strategies against severe diseases caused by the virus and building of novel research tools to improve citrus varieties. Reaching these goals will allow us to advance this project to a new phase of turning the virus from a pathogen to an ally.
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Mawassi, Munir, Adib Rowhani, Deborah A. Golino, Avichai Perl i Edna Tanne. Rugose Wood Disease of Grapevine, Etiology and Virus Resistance in Transgenic Vines. United States Department of Agriculture, listopad 2003. http://dx.doi.org/10.32747/2003.7586477.bard.
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Rugose wood is a complex disease of grapevines, which occurs in all growing areas. The disease is spread in the field by vector transmission (mealybugs). At least five elongated-phloem- limited viruses are implicated in the various rugose wood disorders. The most fully characterized of these are Grapevine virus A (GV A) and GVB, members of a newly established genus, the vitivirus. GVC, a putative vitivirus, is much less well characterized than GV A or GVB. The information regarding the role of GVC in the etiology and epidemiology of rugose wood is fragmentary and no sequence data for GVC are available. The proposed research is aimed to study the etiology and epidemiology of rugose wood disease, and to construct genetically engineered virus-resistant grapevines. The objectives of our proposed research were to construct transgenic plants with coat protein gene sequences designed to induce post-transcriptional gene silencing (pTGS); to study the epidemiology and etiology of rugose wood disease by cloning and sequencing of GVC; and surveying of rugose wood- associated viruses in Californian and Israeli vineyards. In an attempt to experimentally define the role of the various genes of GV A, we utilized the infectious clone, inserted mutations in every ORF, and studied the effect on viral replication, gene expression, symptoms and viral movement. We explored the production of viral RNAs in a GV A-infected Nicotiana benthamiana herbaceous host, and characterized one nested set of three 5'-terminal sgRNAs of 5.1, 5.5 and 6.0 kb, and another, of three 3'-terminal sgRNAs of 2.2, 1.8 and 1.0 kb that could serve for expression of ORFs 2-3, respectively. Several GV A constructs have been assembled into pCAMBIA 230 I, a binary vector which is used for Angrobacterium mediated transformation: GV A CP gene; two copies of the GV A CP gene arranged in the same antisense orientation; two copies of the GV A CP gene in which the downstream copy is in an antigens orientation; GV A replicase gene; GV A replicase gene plus the 3' UTR sequence; and the full genome of GV A. Experiments for transformation of N. benthamiana and grapevine cell suspension with these constructs have been initiated. Transgenic N. benthamiana plants that contained the CP gene, the replicase gene and the entire genome of GV A were obtained. For grapevine transformation, we have developed efficient protocols for transformation and successfully grapevine plantlets that contained the CP gene and the replicase genes of GV A were obtained. These plants are still under examination for expression of the trans genes. The construction of transgenic plants with GV A sequences will provide, in the long run, a means to control one of the most prevalent viruses associated with grapevines. Our many attempts to produce a cDNA library from the genome of GVC failed. For surveying of rugose wood associated viruses in California vineyards, samples were collected from different grape growing areas and tested by RT-PCR for GV A, GVB and GVD. The results indicated that some of the samples were infected with multiple viruses, but overall, we found higher incidence of GVB and GV A infection in California vineyards and new introduction varieties, respectively. In this research we also conducted studies to increase our understanding of virus - induced rootstock decline and its importance in vineyard productivity. Our results provided supporting evidence that the rootstock response to virus infection depends on the rootstock genotype and the virus type. In general, rootstocks are differ widely in virus susceptibility. Our data indicated that a virus type or its combination with other viruses was responsible in virus-induced rootstock decline. As the results showed, the growth of the rootstocks were severely affected when the combination of more than one virus was present.
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Lapidot, Moshe, i Vitaly Citovsky. molecular mechanism for the Tomato yellow leaf curl virus resistance at the ty-5 locus. United States Department of Agriculture, styczeń 2016. http://dx.doi.org/10.32747/2016.7604274.bard.
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Tomato yellow leaf curl virus (TYLCV) is a major pathogen of tomato that causes extensive crop loss worldwide, including the US and Israel. Genetic resistance in the host plant is considered highly effective in the defense against viral infection in the field. Thus, the best way to reduce yield losses due to TYLCV is by breeding tomatoes resistant or tolerant to the virus. To date, only six major TYLCV-resistance loci, termed Ty-1 to Ty-6, have been characterized and mapped to the tomato genome. Among tomato TYLCV-resistant lines containing these loci, we have identified a major recessive quantitative trait locus (QTL) that was mapped to chromosome 4 and designated ty-5. Recently, we identified the gene responsible for the TYLCV resistance at the ty-5 locus as the tomato homolog of the gene encoding messenger RNA surveillance factor Pelota (Pelo). A single amino acid change in the protein is responsible for the resistant phenotype. Pelo is known to participate in the ribosome-recycling phase of protein biosynthesis. Our hypothesis was that the resistant allele of Pelo is a “loss-of-function” mutant, and inhibits or slows-down ribosome recycling. This will negatively affect viral (as well as host-plant) protein synthesis, which may result in slower infection progression. Hence we have proposed the following research objectives: Aim 1: The effect of Pelota on translation of TYLCV proteins: The goal of this objective is to test the effect Pelota may or may not have upon translation of TYLCV proteins following infection of a resistant host. Aim 2: Identify and characterize Pelota cellular localization and interaction with TYLCV proteins: The goal of this objective is to characterize the cellular localization of both Pelota alleles, the TYLCV-resistant and the susceptible allele, to see whether this localization changes following TYLCV infection, and to find out which TYLCV protein interacts with Pelota. Our results demonstrate that upon TYLCV-infection the resistant allele of pelota has a negative effect on viral replication and RNA transcription. It is also shown that pelota interacts with the viral C1 protein, which is the only viral protein essential for TYLCV replication. Following subcellular localization of C1 and Pelota it was found that both protein localize to the same subcellular compartments. This research is innovative and potentially transformative because the role of Peloin plant virus resistance is novel, and understanding its mechanism will lay the foundation for designing new antiviral protection strategies that target translation of viral proteins. BARD Report - Project 4953 Page 2
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Bercovier, Herve, i Ronald P. Hedrick. Diagnostic, eco-epidemiology and control of KHV, a new viral pathogen of koi and common carp. United States Department of Agriculture, grudzień 2007. http://dx.doi.org/10.32747/2007.7695593.bard.
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Original objectives and revisions-The proposed research included these original objectives: field validation of diagnostic tests (PCR), the development and evaluation of new sensitive tools (LC-PCR/TaqManPCR, antibody detection by ELISA) including their use to study the ecology and the epidemiology of KHV (virus distribution in the environment and native cyprinids) and the carrier status of fish exposed experimentally or naturally to KHV (sites of virus replication and potential persistence or latency). In the course of the study we completed the genome sequence of KHV and developed a DNA array to study the expression of KHV genes in different conditions. Background to the topics-Mass mortality of koi or common carp has been observed in Israel, USA, Europe and Asia. These outbreaks have reduced exports of koi from Israel and have created fear about production, import, and movements of koi and have raised concerns about potential impacts on native cyprinid populations in the U.S.A. Major conclusions-A suite of new diagnostic tools was developed that included 3 PCR assays for detection of KHV DNA in cell culture and fish tissues and an ELISA assay capable of detecting anti-KHV antibodies in the serum of koi and common carp. The TKPCR assay developed during the grant has become an internationally accepted gold standard for detection of viral DNA. Additionally, the ELISA developed for detecting serum anti-KHV antibodies is now in wide use as a major nonlethal screening tool for evaluating virus status of koi and common carp populations. Real time PCR assays have been able to detect viral DNA in the internal organs of survivors of natural and wild type vaccine exposures at 1 and 10³ genome equivalents at 7 months after exposure. In addition, vaccinated fish were able to transmit the virus to naive fish. Potential control utilizing hybrids of goldfish and common carp for production demonstrated they were considerably more resistant than pure common carp or koi to both KHV (CyHV-3). There was no evidence that goldfish or other tested endemic cyprinids species were susceptible to KHV. The complete genomic sequencing of 3 strains from Japan, the USA, and Israel revealed a 295 kbp genome containing a 22 kbp terminal direct repeat encoding clear gene homologs to other fish herpesviruses in the family Herpesviridae. The genome encodes156 unique protein-coding genes, eight of which are duplicated in the terminal repeat. Four to seven genes are fragmented and the loss of these genes may be associated with the high virulence of the virus. Viral gene expression was studies by a newly developed chip which has allowed verification of transcription of most all hypothetical genes (ORFs) as well as their kinetics. Implications, both scientific and agricultural- The results from this study have immediate application for the control and management of KHV. The proposal provides elements key to disease management with improved diagnostic tools. Studies on the ecology of the virus also provide insights into management of the virus at the farms that farmers will be able to apply immediately to reduce risks of infections. Lastly, critical issues that surround present procedures used to create “resistant fish” must be be resolved (e.g. carriers, risks, etc.). Currently stamping out may be effective in eradicating the disease. The emerging disease caused by KHV continues to spread. With the economic importance of koi and carp and the vast international movements of koi for the hobby, this disease has the potential for even further spread. The results from our studies form a critical component of a comprehensive program to curtail this emerging pathogen at the local, regional and international levels.
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Chejanovsky, Nor, Diana Cox-Foster, Victoria Soroker i Ron Ophir. Honeybee modulation of infection with the Israeli acute paralysis virus, in asymptomatic, acutely infected and CCD colonies. United States Department of Agriculture, grudzień 2013. http://dx.doi.org/10.32747/2013.7594392.bard.
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Honey bee (Apis mellifera) colony losses pose a severe risk to the food chain. The IAPV (Israeli acute paralysis virus) was correlated with CCD, a particular case of colony collapse. Honey bees severely infected with IAPV show shivering wings that progress to paralysis and subsequent death. Bee viruses, including IAPV, are widely present in honey bee colonies but often there are no pathological symptoms. Infestation of the beehive with Varroa mites or exposure to stress factors leads to significant increase in viral titers and fatal infections. We hypothesized that the honey bee is regulating/controlling IAPV and viral infections in asymptomatic infections and this control is broken through "stress" leading to acute infections and/or CCD. Our aims were: 1. To discover genetic changes in IAPV that may affect tissue tropism in the host, and/or virus infectivity and pathogenicity. 2. To elucidate mechanisms used by the host to regulate/ manage the IAPV-infection in vivo and in vitro. To achieve the above objectives we first studied stress-induced virus activation. Our data indicated that some pesticides, including myclobutanil, chlorothalonil and fluvalinate, result in amplified viral titers when bees are exposed at sub lethal levels by a single feeding. Analysis of the level of immune-related bee genes indicated that CCD-colonies exhibit altered and weaker immune responses than healthy colonies. Given the important role of viral RNA interference (RNAi) in combating viral infections we investigated if CCD-colonies were able to elicit this particular antiviral response. Deep-sequencing analysis of samples from CCD-colonies from US and Israel revealed high frequency of small interfering RNAs (siRNA) perfectly matching IAPV, Kashmir bee virus and Deformed wing virus genomes. Israeli colonies showed high titers of IAPV and a conserved RNAi pattern of targeting the viral genome .Our findings were further supported by analysis of samples from colonies experimentally infected with IAPV. Following for the first time the dynamics of IAPV infection in a group of CCD colonies that we rescued from collapse, we found that IAPV conserves its potential to act as one lethal, infectious factor and that its continuous replication in CCD colonies deeply affects their health and survival. Ours is the first report on the dominant role of IAPV in CCD-colonies outside from the US under natural conditions. We concluded that CCD-colonies do exhibit a regular siRNA response that is specific against predominant viruses associated with colony losses and other immune pathways may account for their weak immune response towards virus infection. Our findings: 1. Reveal that preventive measures should be taken by the beekeepers to avoid insecticide-based stress induction of viral infections as well as to manage CCD colonies as a source of highly infectious viruses such as IAPV. 2. Contribute to identify honey bee mechanisms involved in managing viral infections.
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Gafny, Ron, A. L. N. Rao i Edna Tanne. Etiology of the Rugose Wood Disease of Grapevine and Molecular Study of the Associated Trichoviruses. United States Department of Agriculture, wrzesień 2000. http://dx.doi.org/10.32747/2000.7575269.bard.
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Rugose wood is a complex disease of grapevines, characterized by modification of the woody cylinder of affected vines. The control of rugose wood is based on the production of healthy propagation material. Detection of rugose wood in grapevines is difficult and expensive: budwood from tested plants is grafted onto sensitive Vitis indicators and the appearance of symptoms is monitored for 3 years. The etiology of rugose wood is complex and has not yet been elucidated. Several elongated clostero-like viruses are consistently found in affected vines; one of them, grapevine virus A (GVA), is closely associated with Kober stem grooving, a component of the rugose wood complex. GVA has a single-stranded RNA genome of 7349 nucleotides, excluding a polyA tail at the 3' terminus. The GVA genome includes five open reading frames (ORFs 1-5). ORF 4, which encodes for the coat protein of GVA, is the only ORF for which the function was determined experimentally. The original objectives of this research were: 1- To produce antisera to the structural and non-structural proteins of GVA and GVB and to use these antibodies to establish an effective detection method. 2- Develop full length infectious cDNA clones of GVA and GVB. 3- Study the roll of GVA and GVB in the etiology of the grapevine rugose wood disease. 4- Determine the function of Trichovirus (now called Vitivirus) encoded genes in the virus life cycle. Each of the ORFs 2, 3, 4 and 5 genes of GVA were cloned and expressed in E. coli and used to produce antisera. Both the CP (ORF 4) and the putative MP (ORF 3) were detected with their corresponding antisera in-GVA infected N. benthamiana and grapevine. The MP was first detected at an early stage of the infection, 6-12 h after inoculation, and the CP 2-3 days after inoculation. The MP could be detected in GVA-infected grapevines that tested negative for CP, both with CP antiserum and with a commercially available ELISA kit. Antisera to ORF 2 and 5 encoded proteins could react with the recombinant proteins but failed to detect both proteins in GVA infected plants. A full-length cDNA clone of grapevine virus A (GVA) was constructed downstream from the bacteriophage T7 RNA polymerase promoter. Capped in vitro transcribed RNA was infectious in N. benthamiana and N. clevelandii plants. Symptoms induced by the RNA transcripts or by the parental virus were indistinguishable. The infectivity of the in vitro-transcribed RNA was confirmed by serological detection of the virus coat and movement proteins and by observation of virions by electron microscopy. The full-length clone was modified to include a gus reporter gene and gus activity was detected in inoculated and systemic leaves of infected plants. Studies of GVA mutants suggests that the coat protein (ORF 4) is essential for cell to cell movement, the putative movement protein (ORF 3) indeed functions as a movement protein and that ORF 2 is not required for virus replication, cell to cell or systemic movement. Attempts to infect grapevines by in-vitro transcripts, by inoculation of cDNA construct in which the virus is derived by the CaMV 35S promoter or by approach grafting with infected N. benthamiana, have so far failed. Studies of the subcellular distribution of GFP fusion with each of ORF 2, 3 and 4 encoded protein showed that the CP fusion protein accumulated as a soluble cytoplasmatic protein. The ORF 2 fusion protein accumulated in cytoplasmatic aggregates. The MP-GFP fusion protein accumulated in a large number of small aggregates in the cytoplasm and could not move from cell to cell. However, in conditions that allowed movement of the fusion protein from cell to cell (expression by a PVX vector or in young immature leaves) the protein did not form cytoplasmatic aggregates but accumulated in the plasmodesmata.
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Gelb, Jr., Jack, Yoram Weisman, Brian Ladman i Rosie Meir. Identification of Avian Infectious Brochitis Virus Variant Serotypes and Subtypes by PCR Product Cycle Sequencing for the Rational Selection of Effective Vaccines. United States Department of Agriculture, grudzień 2003. http://dx.doi.org/10.32747/2003.7586470.bard.
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Objectives 1. Determine the serotypic identities of 40 recent IBV isolates from commercial chickens raised in the USA and Israel. 2. Sequence all IBV field isolates using PCR product cycle sequencing and analyze their S 1 sequence to detennine their homology to other strains in the Genbank and EMBL databases. 3. Select vaccinal strains with the highest S 1 sequence homology to the field isolates and perform challenge of immunity studies in chickens in laboratory trials to detennine level of protection afforded by the vaccines. Background Infectious bronchitis (IB) is a common, economically important disease of the chicken. IB occurs as a respiratory form, associated with airsacculitis, condemnation, and mortality of meat-type broilers, a reproductive form responsible for egg production losses in layers and breeders, and a renal form causing high mortality in broilers and pullets. The causative agent is avian coronavirus infectious bronchitis virus (IBV). Replication of the virus' RNA genome is error-prone and mutations commonly result. A major target for mutation is the gene encoding the spike (S) envelope protein used by the virus to attach and infect the host cell. Mutations in the S gene result in antigenic changes that can lead to the emergence of variant serotypes. The S gene is able to tolerate numerous mutations without compromising the virus' ability to replicate and cause disease. An end result of the virus' "flexibility" is that many strains of IBV are capable of existing in nature. Once formed, new mutant strains, often referred to as variants, are soon subjected to immunological selection so that only the most antigenically novel variants survive in poultry populations. Many novel antigenic variant serotypes and genotypes have been isolated from commercial poultry flocks. Identification of the field isolates of IBV responsible for outbreaks is critical for selecting the appropriate strain(s) for vaccination. Reverse transcriptase polymerase chain reaction (RT-PCR) of the Sl subunit of the envelope spike glycoprotein gene has been a common method used to identify field strains, replacing other time-consuming or less precise tests. Two PCR approaches have been used for identification, restriction fragment length polymorphism (RFLP) and direct automated cycle sequence analysis of a diagnostically relevant hypervariab1e region were compared in our BARD research. Vaccination for IB, although practiced routinely in commercial flocks, is often not protective. Field isolates responsible for outbreaks may be unrelated to the strain(s) used in the vaccination program. However, vaccines may provide varying degrees of cross- protection vs. unrelated field strains so vaccination studies should be performed. Conclusions RFLP and S1 sequence analysis methods were successfully performed using the field isolates from the USA and Israel. Importantly, the S1 sequence analysis method enabled a direct comparison of the genotypes of the field strains by aligning them to sequences in public databases e.g. GenBank. Novel S1 gene sequences were identified in both USA and Israel IBVs but greater diversity was observed in the field isolates from the USA. One novel genotype, characterized in this project, Israel/720/99, is currently being considered for development as an inactivated vaccine. Vaccination with IBV strains in the US (Massachusetts, Arkansas, Delaware 072) or in Israel (Massachusetts, Holland strain) provided higher degrees of cross-protection vs. homologous than heterologous strain challenge. In many cases however, vaccination with two strains (only studies with US strains) produced reasonable cross-protection against heterologous field isolate challenge. Implications S1 sequence analysis provides numerical similarity values and phylogenetic information that can be useful, although by no means conclusive, in developing vaccine control strategies. Identification of many novel S1 genotypes of IBV in the USA is evidence that commercial flocks will be challenged today and in the future with strains unrelated to vaccines. In Israel, monitoring flocks for novel IBV field isolates should continue given the identification of Israel/720/99, and perhaps others in the future. Strains selected for vaccination of commercial flocks should induce cross- protection against unrelated genotypes. Using diverse genotypes for vaccination may result in immunity against unrelated field strains.