Download or read book Vaccinia Virus Ribonucleotide Reductase written by Meredith L. Howell and published by . This book was released on 1992 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ribonucleotide reductase is a remarkable enzyme that catalyzes the rate-limiting step in the synthesis of the 2'-deoxynucleoside triphosphates. The intent of this project was to characterize the ribonucleotide reductase encoded by the orthopoxvirus, vaccinia. The first objective was to study the structural and functional features of the viral small subunit protein of ribonucleotide reductase. The viral reductase gene was engineered into an expression vector and expressed in Escherichia coli. The purified recombinant protein was then characterized and compared with other ribonucleotide reductase small subunits from different organisms. The physical characteristics of the vaccinia virus enzyme showed a strong similarity to the features of the mammalian counterpart. A second aim of this project was to establish the transcriptional and translational kinetics of ribonucleotide reductase gene expression during the time course of viral infection in cultured mammalian cells. In addition, the activity and stability of the enzyme in the viral system was measured and the accumulation of ribonucleotide reductase protein was quantitated. By also quantitating the accumulation of viral DNA synthesis, a direct comparison can be made between the the synthesis and utilization of deoxynucleotide precursors. A third objective of this work was to detail the mechanism by which hydroxyurea inactivates the vaccinia virus ribonucleotide reductase. Visible spectroscopy and electron paramagnetic resonance spectroscopy clearly demonstrated that the inhibitor destroys the free radical moiety in the viral small subunit protein. In addition, in vivo studies revealed that inhibition by hydroxyurea can be circumvented during viral infection. The exogenous addition of deoxyadenosine reversed the block to viral growth that was imposed by hydroxyurea, and stabilized hydroxyurea induced deoxynucleotide pool imbalances. These inhibition studies suggest that there may be a differential sensitivity of the enzyme towards hydroxyurea in the presence of various substrates.
Download or read book Vaccinia Virus Ribonucleotide Reductase written by Ralph Eugene Davis and published by . This book was released on 1992 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vaccinia virus infected monkey kidney cells had been previously shown to have an increased ribonucleoside diphosphate reductase (RR) activity. DNA from mutant virus resistant to hydroxyurea were digested with restriction endonucleases and were shown to have substoichiometric amounts of the Hind III F fragment. Additional information from Southern blotting experiments localized the putative small subunit (R2) gene to the left end of the Hind III F fragment of the vaccinia virus genome. The entire open reading frame of the R2 gene and the flanking regions was sequenced and the translated sequence found to be 80% homologous to the mouse R2 polypeptide. A combination of in situ and in vitro experiments addressed the question of macromolecular interactions involving vaccinia ribonucleotide reductase (FIR). Replication of double stranded viral DNA occurs in very discrete loci in infected cells and these DNA factories can be isolated from gently lysed cell in sucrose gradients. RR was detected at low levels (less than 5% of the total R2) with the rapidly sedimenting DNA by using antibodies against FIR. In situ crosslinking experiments were attempted with no specific interaction determined at this time. Immunolocalization experiments have given evidence for localization of large subunit (R1) polypeptide to the viral inclusion bodies. The most conclusive results utilized anti-idiotypic antibodies against the antibodies to R2 protein. lmmunolocalization experiments have shown the putative R2 binding protein to be localized at the sites of viral DNA synthesis. lmmunoprecipitations show a single predominant viral polypeptide which also has proven to be a DNA binding (phospho)protein. Screening a lambda phale expression library of vaccinia with the anti-idiotypic antibody localized the binding site to the carboxy terminal 81 amino acids in open reading frame 1-3 of the vaccinia genome. The open reading frame was cloned into a pET11c expression vector and the partially purified recombinant protein was shown to have specificity for single-stranded DNA as well as stimulate vaccinia RR activity.
Download or read book Vaccinia Virus DNA Polymerase and Ribonucleotide Reductase written by Donald Brad Gammon and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Large Subunit of Vaccinia Cirus Ribonucleotide Reductase written by Rainer K. Warth and published by . This book was released on 1993 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ribonucleoside diphosphate reductase (RR) from vaccinia virus was recently cloned and overexpressed rn Escherichia coli. The amino acid sequence identities of the small and large subunits between the mouse and the vaccinia virus reductase are approximately 80 and 72 percent, respectively. In addition, vaccinia virus RR displays similar complex allosteric regulation to the mouse enzyme and other eukaryotic reductases. The overall activity of the enzyme, which has two subunits (Rl and R2), is regulated through binding to ATP, which activates the enzyme, and dATP which seryes as an inhibitor. Both nucleotides bind to the same allosteric site, called the activity site, on the large subunit of RR. The specificity of the enzyme towards the four ribonucleoside diphosphate substrates is regulated by the binding of ATP, dATP, dTTP and GTp. Each of these nucleotides affects the reduction of a specific nucleoside diphosphate. Although this enzyme's allosteric regulation is kinetically well understood it has not been possible so far to gain further structural information about the location of the activity site and specificity site. The use of deletion mutants and photoaffinity labeling of the large subunit to identify the location of the binding sites is the incentive for this thesis. With the introduction of 6xHis/Nickel Nitrilo-tri-acetic acid (Ni-NTA) chromatography, the purification of the large subunit was improved in the E. coli and vaccinia virus/T7 RNA polymerase hybrid system. The purification of several deletion mutant forms of the large subunit was also attempted, but it was not possible to purify any of them from either of the expression systems. The purified full-length large subunit obtained with the Ni-NTA-chromatography system was used for a photoaffinity labeling experiment with [32P]dATP and [32P]dTTP. The labeled proteins were proteolytically digested to find out about the specificity of the labeling experiment and also to map the binding site of the nucleotide. It was found that labeling of dATP yielded few discrete bands indicating specific binding, while a comparable experiment with dTTP indicated less specific binding, based on a larger number of labeled bands. In competition experiments with non-radioactive nucleotides, vaccinia virus R1 featured the same properties as the mouse and E. coli counterparts. This is consistent with data from kinetic experiments, which also establish the same kinetic properties between vaccinia virus RR with those of mouse and E. coli (RR). To identify the sequence of the fragments carrying the label the digests were subjected to mass spectrometric analysis. However, it was not possible to determine the sequence of the labeled fragment by mass spectrometry due to poor spectral resolution.
Download or read book Poxviruses written by Richard W. Moyer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this volume is to highlight some current areas of poxvirus research which are likely to be particularly fruitful in the upcoming few years. The first chapter, by Drs. Condit and Niles, discusses poxvirus genetics. Work in this area has provided mutants, produced practical procedures to simplify the manipulation of viral genes, and generated information about the molecular architecture and organization of genes characteristic of pox viruses. One of the most intensively studied regions of the viral genome is the HindIII D region of vaccinia, in which a combination of classical and molecular genetic analysis of the region has been particularly revealing. Within this region are open reading frames, some of which are expressed early and others late, organized in a fashion which is now known to be typical of these viruses. Other studies, related to temperature sensitive, drug resistant, and drug dependent mutants, are also discussed. Each of the other reviews included in this volume summarizes areas of research which have depended heavily on the genetics of the system. The intracellular site of a poxvirus infection is mostly, if not exclusively, limited to the cytoplasm which dictates several interesting biological ramifications. For example, poxvirus transcription must occur in the cytoplasm, rather than in the nucleus. The virus copes with this situation by incorporating into the virion the enzymatic machinery necessary to initiate transcription from input virus.
Download or read book Ranaviruses written by Matthew J. Gray and published by Springer. This book was released on 2015-05-01 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book on ranaviruses. Ranaviruses are double-stranded DNA viruses that cause hemorrhagic disease in amphibians, reptiles, and fish. They have caused mass die-offs of ectothermic vertebrates in wild and captive populations around the globe. There is evidence that this pathogen is emerging and responsible for population declines in certain locations. Considering that amphibians and freshwater turtles are suitable hosts and the most imperiled vertebrate taxa in the world, ranaviruses can have significant impacts on biodiversity and ecosystem function. Additionally, many fish that are raised in aquaculture facilities and traded internationally are suitable hosts; thus, the potential economic impact of ranaviruses is significant. Ranaviruses also serve as a model for replication and gene function of large double-stranded DNA viruses. There is an urgent need to assemble the contemporary information on ranaviruses and provide guidance on how to assess their threats in populations. Through the Global Ranavirus Consortium, 24 experts from six countries were organize to write this volume, the first book on ranaviruses. The book begins with a discussion on the global extent of ranaviruses, case histories of infection and disease in ectothermic vertebrates, and current phylogeny. Basic principles of ranavirus ecology and evolution are covered next, with a focus on host-pathogen interactions and how the virus emerges in its environment. There are two chapters that will discuss the molecular biology of ranaviruses, host response to infection, and the genes responsible for immune system evasion. One chapter establishes standards for testing for infection and diagnosing ranaviral disease. The book ends by providing guidance on how to design ranavirus surveillance studies and analyze data to determine risk, and discussing the role of the Global Ranavirus Consortium in organizing research and outreach activities.
Download or read book Human Herpesviruses written by Ann Arvin and published by Cambridge University Press. This book was released on 2007-08-16 with total page 1325 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive account of the human herpesviruses provides an encyclopedic overview of their basic virology and clinical manifestations. This group of viruses includes human simplex type 1 and 2, Epstein–Barr virus, Kaposi's Sarcoma-associated herpesvirus, cytomegalovirus, HHV6A, 6B and 7, and varicella-zoster virus. The viral diseases and cancers they cause are significant and often recurrent. Their prevalence in the developed world accounts for a major burden of disease, and as a result there is a great deal of research into the pathophysiology of infection and immunobiology. Another important area covered within this volume concerns antiviral therapy and the development of vaccines. All these aspects are covered in depth, both scientifically and in terms of clinical guidelines for patient care. The text is illustrated generously throughout and is fully referenced to the latest research and developments.
Download or read book Oncolytic Viruses Genetically Engineering the Future of Cancer Therapy written by Benjamin Gesundheit and published by Frontiers Media SA. This book was released on 2016-11-22 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to genetically engineer oncolytic viruses in order to minimize side effects and improve the selective targeting of tumor cells has opened up novel opportunities for treating cancer. Understanding the mechanisms involved and the complex interaction between the viruses and the immune system will undoubtedly help guide the development of new strategies. Theranostic biomarkers to monitor these therapies in clinical trials serve an important need in this innovative field and demand further research.
Download or read book Virus Taxonomy written by International Committee on Taxonomy of Viruses and published by Elsevier. This book was released on 2011-10-25 with total page 1463 pages. Available in PDF, EPUB and Kindle. Book excerpt: The practical need to partition the world of viruses into distinguishable, universally agreed upon entities is the ultimate justification for developing a virus classification system. Since 1971, the International Committee on Taxonomy of Viruses (ICTV) operating on behalf of the world community of virologists has taken on the task of developing a single, universal taxonomic scheme for all viruses infecting animals (vertebrate, invertebrates, and protozoa), plants (higher plants and algae), fungi, bacteria, and archaea. The current report builds on the accumulated taxonomic construction of the eight previous reports dating back to 1971 and records the proceedings of the Committee since publication of the last report in 2005. Representing the work of more than 500 virologists worldwide, this report is the authoritative reference for virus organization, distinction, and structure.
Download or read book Poxviruses written by Andrew Mercer and published by Springer Science & Business Media. This book was released on 2007-02-15 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph provides a comprehensive review of the poxvirus family with a particular emphasis on current developments. It includes the latest insights into poxviral molecular biology, diagnosis, therapy, vaccine development and the beneficial exploitation of these viruses in biomedical research. Each chapter is written by a leader in the field, and the book includes historical perspectives and summaries of recent advances in the field.
Download or read book Orthopoxviruses Pathogenic for Humans written by and published by Springer Science & Business Media. This book was released on 2006-06-09 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orthopoxviruses Pathogenic for Humans covers those viruses capable of causing disease in man, including monkeypox, smallpox, cowpox, and vaccinia. The coverage of each virus is comprehensive, covering the biology, molecular biology, and ecology of the virus as well as the clinical and epidemiological aspects of these viruses in humans and animals. In addition, this volume highlights developments in genetic engineering that are paving the way for potential therapeutic treatments of these viruses.
Download or read book The Baculoviruses written by Lois K. Miller and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 459 pages. Available in PDF, EPUB and Kindle. Book excerpt: The past decade has witnessed an explosion of information on the molecular biology of insect viruses and a frenzy of activity in applying this information to medicine and agriculture. Genetically engineered baculoviruses are presently being tested for commercial use as pesticides, and the study of such viruses is also revealing remarkable insights into basic cellular processes such as apoptosis. This comprehensive volume provides readers with knowledge of basic and applied baculovirology so that current literature in the field can be appreciated.
Download or read book Recombinant Poxviruses written by Matthew M. Binns and published by CRC Press. This book was released on 1992-05-27 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recombinant Poxviruses provides a comprehensive examination of poxviruses with an emphasis on the potential of these viruses as new vaccines. The book considers a wide range of issues involved in producing new genetically engineered live vaccines, such as efficacy, safety, stability, cost, host range, immune response, immunization route, use of multivalent vaccines, and need for revaccination. The opening chapter describes the origin of vaccinia virus, its use to eradicate smallpox, and the pathogenesis of poxvirus infections. Subsequent chapters examine the molecular biology of poxviruses, methods of constructing vaccinia virus recombinants, and applications; the use and immune responses induced by poxvirus recombinants as live vaccines; and the important issues of the safety and immunogenicity of vaccinia virus. The book's final two chapters report the progress that has been made developing avipoxviruses and parapoxviruses as candidate recombinant vaccines. Recombinant Poxviruses will be a welcome addition to the bookshelves of virologists, microbiologists, infectious disease specialists, and veterinarians.
Download or read book Viral Genome Replication written by Craig E. Cameron and published by Springer Science & Business Media. This book was released on 2009-05-28 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides the first comprehensive review of viral genome replication strategies, emphasizing not only pathways and regulation but also the structure-function, mechanism, and inhibition of proteins and enzymes required for this process.
Download or read book The Orthopoxviruses written by Frank Fenner and published by Elsevier. This book was released on 2012-12-02 with total page 443 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Orthopoxviruses presents knowledge and comprehensive and integrated picture of orthopoxviruses. The book looks into the molecular biology of this genusof viruses, particularly, the structure and chemical composition of the virion, replication, morphogenesis, pathogenesis, pathology, and immunology of this virus' infections. It also elucidates the global spread, control, and eradication of smallpox. Additionally, the book describes a potentially important use of vaccinia virus, namely, its use as a vector for genes from other viruses, bacteria, or protozoa that specify antigens important in stimulating the production of a protective immune response. Such comprehensive account of all aspects of the biology of all known species of orthopoxviruses will be valuable to molecular biologists, virologists, immunologists, pathologists, and researchers in the veterinary sciences.
Download or read book Fields Virology DNA Viruses written by Peter M. Howley and published by Lippincott Williams & Wilkins. This book was released on 2021-05-17 with total page 2429 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bundled with the eBook, which will be updated regularly as new information about each virus is available, this text serves as the authoritative, up-to-date reference book for virologists, infectious disease specialists, microbiologists, and physicians, as well as medical students pursuing a career in infectious diseases.
Download or read book Allosteric Enzymes written by Guy Herve and published by CRC Press. This book was released on 2020-11-26 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book compiles detailed information concerning a dozen of the best known allosteric enzymes, and so allows the comparison of their regulatory mechanisms and the confrontation of these mechanisms with the theoretical models. Stimulating and unexpected ideas emerge from these comparisons and emphasize the importance of developing various methods of investigation such as crystallography, X-ray solution scattering, and the study of fast movements in proteins and site-directed mutagenesis. This book is addressed to students and researchers interested in structure-function relationship in proteins, enzymology and metabolic regulation. It is also a basis for teaching.
