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Elucidating Mechanisms of Eukaryotic Genetic Expression by Studying Animal Viruses AARON 1. SHATIGN* Eukaryotic genetic expression is carefully regulated. Normal cell growth and division, tis sue differentiation, and organism development all depend on a strictly ordered progres sion of specific events. Perturbation of the control of these processes, for example by ex posure to harmful chemicals or infection with viruses leads to aberrant forms of meta bolism, often resulting in malignancies and cell death. One of the most challenging problems in biology is to derme at the molecular level the mechanisms that govern gene function in higher organisms, including ultimately man. This goal serves to unify the diverse efforts of many investigators, whether studying the precise patterns of embryo genesis, the loss of control that occurs during neoplastic growth or the redirection of biosynthetic pathways in virus-infected cells. Recently there has been remarkable and exciting progress toward understanding the molecular biology of eukaryotic expression. Much of this rapidly increasing new infor mation has come from studies of animal virus systems. Just as investigations of the relatively simple, rapidly assayed, and easily manipulated bacteriophages lead to basic discoveries about prokaryotic cells, analyses of animal viruses and their interactions with host cells have provided fundamental information about how eukaryotic nucleic acids are organized for regulated replication, transcription, and translation. For example, the small genome of SV , like cellular DNA in chromatin, is associated with histones to 40 form nucleosomal arrays (Griffin 1975).
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.
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.
The Epstein-Barr virus was discovered 15 years ago. Since that time an immense body of information has been accumu lated on this agent which has come to assume great signifi cance in many different fields of biological science. Thus, the virus has very special relevance in human medicine and oncology, in tumor virology, in immunology, and in mole cular virology, since it is the cause of infectious mononu cleosis and also the first human cancer virus, etiologically related to endemic Burkitt's lymphoma and probably to nasopharyngeal carcinoma. In addition, continuous human lymphoid cell lines initiated and maintained by the transform ing function of the virus genome provide a laboratory tool with wide and ever-growing applications. Innumerable papers on the Epstein-Barr virus have ap peared over recent years and reports of work with this agent now constitute a veritable flood. The present book provides the first and only comprehensive, authoritative over-view of all aspects of the virus by authors who have been the original and major contributors in their particular disciplines. A complete and up-to-date survey of this unique and important agent is thus provided which should be of great interest to experts, teachers, and students engaged in cancer research, virology, immunology, molecular biology, epide miology, and cell culture. Where topics have been dealt with from more than one of these viewpoints, some inevitable overlap and duplication has resulted; although this has been kept to a minimum, it has been retained in some places because of positive usefulness.
It has been ten years since the publication of the third edition of this seminal text on plant virology, during which there has been an explosion of conceptual and factual advances. The fourth edition updates and revises many details of the previous editon, while retaining the important older results that constitute the field's conceptual foundation. Key features of the fourth edition include: * Thumbnail sketches of each genera and family groups * Genome maps of all genera for which they are known * Genetic engineered resistance strategies for virus disease control * Latest understanding of virus interactions with plants, including gene silencing * Interactions between viruses and insect, fungal, and nematode vectors * New plate section containing over 50 full-color illustrations.
Epstein-Barr virus lytic replication is accomplished by an intricate cascade of gene expression that integrates viral DNA replication and structural protein synthesis. Most genes encoding structural proteins exhibit "true" late kinetics - their expression is strictly dependent on lytic DNA replication. Recently, the EBV BcRF1 gene was reported to encode a TATA box binding protein homolog, which preferentially recognizes the TATT sequence found in true late gene promoters. BcRF1 is one of seven EBV genes with homologs found in other [small beta]- and [small gamma]-, but not in [small alpha]-herpesviruses. Using EBV BACmids, we systematically disrupted each of these "[small beta][small gamma]" genes. We found that six of them, including BcRF1, exhibited an identical phenotype: intact viral DNA replication with loss of late gene expression. The proteins encoded by these six genes have been found by other investigators to form a viral protein complex that is essential for activation of TATT-containing reporters in EBV-negative HEK293 cells. Unexpectedly, in EBV infected HEK293 cells, we found that TATT reporter activation was weak and non-specific unless an EBV origin of lytic replication (OriLyt) was present in cis. Using two different replication-defective EBV genomes, we demonstrated that OriLyt-mediated DNA replication is required in cis for TATT reporter activation and for late gene expression from the EBV genome. We further demonstrate by fluorescence in situ hybridization that the late BcLF1 mRNA localizes to EBV DNA replication factories. These findings support a model in which the [small beta][small gamma] gene-encoded viral pre-initiation complex (vPIC) mediates late gene transcription from newly replicated viral DNA. While this model explains the dependence of late gene transcription on lytic DNA replication, it does not account for this dependence in [small alpha]-herpesviruses nor for recent reports that some EBV late genes are transcribed independently of vPIC. To rigorously define which transcription start sites (TSS) are dependent on viral lytic DNA replication or the [small beta][small gamma] complex, we performed Cap Analysis of Gene Expression (CAGE)-seq on cells infected with wildtype EBV or EBV mutants defective for DNA replication, [small beta][small gamma] function, or lacking an origin of lytic replication (OriLyt). This approach identified 16 true-late, 32 early, and 16 TSS that are active at low levels early and are further upregulated in a DNA replication-dependent manner (leaky late). Almost all late gene transcription is vPIC-dependent, with BCRF1 (vIL10), BDLF2, and BDLF3 transcripts being notable exceptions. We present evidence that leaky late transcription is not due to a distinct mechanism, but results from superimposition of the early and late transcription mechanisms at the same promoter. Our results represent the most comprehensive characterization of EBV lytic gene expression kinetics reported to date and suggest that most, but not all EBV late genes are vPIC-dependent.
Encyclopedia of Virology, Fourth Edition, Five Volume Set builds on the solid foundation laid by the previous editions, expanding its reach with new and timely topics. In five volumes, the work provides comprehensive coverage of the whole virosphere, making this a unique resource. Content explores viruses present in the environment and the pathogenic viruses of humans, animals, plants and microorganisms. Key areas and concepts concerning virus classification, structure, epidemiology, pathogenesis, diagnosis, treatment and prevention are discussed, guiding the reader through chapters that are presented at an accessible level, and include further readings for those needing more specific information. More than ever now, with the Covid19 pandemic, we are seeing the huge impact viruses have on our life and society. This encyclopedia is a must-have resource for scientists and practitioners, and a great source of information for the wider public. Offers students and researchers a one-stop shop for information on virology not easily available elsewhere Fills a critical gap of information in a field that has seen significant progress in recent years Authored and edited by recognized experts in the field, with a range of different expertise, thus ensuring a high-quality standard
Biology for AP® courses covers the scope and sequence requirements of a typical two-semester Advanced Placement® biology course. The text provides comprehensive coverage of foundational research and core biology concepts through an evolutionary lens. Biology for AP® Courses was designed to meet and exceed the requirements of the College Board’s AP® Biology framework while allowing significant flexibility for instructors. Each section of the book includes an introduction based on the AP® curriculum and includes rich features that engage students in scientific practice and AP® test preparation; it also highlights careers and research opportunities in biological sciences.