Genetic Variation Of Viruses

New viral diseases are emerging continuously. Viruses adapt to new environments at astounding rates. Genetic variability of viruses jeopardizes vaccine efficacy. For many viruses mutants resistant to antiviral agents or host immune responses arise readily, for example, with HIV and influenza. These variations are all of utmost importance for human and animal health as they have prevented us from controlling these epidemic pathogens. This book focuses on the mechanisms that viruses use to evolve, survive and cause disease in their hosts. Covering human, animal, plant and bacterial viruses, it provides both the basic foundations for the evolutionary dynamics of viruses and specific examples of emerging diseases. NEW - methods to establish relationships among viruses and the mechanisms that affect virus evolution UNIQUE - combines theoretical concepts in evolution with detailed analyses of the evolution of important virus groups SPECIFIC - Bacterial, plant, animal and human viruses are compared regarding their interation with their hosts

Virus as Composition, Complexity, Quasispecies, Dynamics, and Biological Implications, Second Edition, explains the fundamental concepts surrounding viruses as complex populations during replication in infected hosts. Fundamental phenomena in virus behavior, such as adaptation to changing environments, capacity to produce disease, and the probability to be transmitted or respond to treatment all depend on virus population numbers. Concepts such as quasispecies dynamics, mutations rates, viral fitness, the effect of bottleneck events, population numbers in virus transmission and disease emergence, and new antiviral strategies are included. The book's main concepts are framed by recent observations on general virus diversity derived from metagenomic studies and current views on the origin and role of viruses in the evolution of the biosphere. Features current views on key steps in the origin of life and origins of viruses Includes examples relating ancestral features of viruses with their current adaptive capacity Explains complex phenomena in an organized and coherent fashion that is easy to comprehend and enjoyable to read Considers quasispecies as a framework to understand virus adaptability and disease processes

Many RNA viruses have been known for decades to be genetically and biologically quite variable. Some well-known examples are influenza viruses, foot and mouth disease viruses, and Newcastle disease virus. During the past decade, it has become clear that most, it not all. , RNA viruses (riboviruses and retroviruses) are much more mutable than was recognized previously, and that this great mutability generates extremely complex populations consisting of indeterminate mixtures of related variants (Le. , "mutant swarms" or "quasispecies" populations). This is also true of DNA viruses (such as hepatitis DNA genomes via RNA transcripts B virus) which replicate their that are reverse-transcribed back to DNA. This hypermutability of RNA replicons provides great biological adaptability for RNA virus genomes. It also allows (but does not necessitate) RNA viruses, so that they can extremely rapid evolution of evolve over a million times more quickly than their eukaryotic DNA-based hosts. The genetics of RNA replicons is so unusual (and often counterintuitive) that it has many important biological conse quences which are neither readily apparent nor widely under stood. Failure to understand the distinctive aspects of RNA genetics frequently generates confusion and controversy and can adversely impact vaccine and antiviral drug programs and other applications of medical virology. The 14 chapters in this volume describe advances in a number of significant areas of RNA virus genetics and evolution.

Genetic Variation Among Influenza Viruses documents the proceedings of ICN-UCLA symposium held in Salt Lake City, Utah, 8-13 March 1981. The symposium brought together people from different disciplines working with the common objective of reducing the ravages of influenza and to expose them to the totality of the problem of influenza. The papers presented at the meeting included nearly all major aspects of influenza in which important advances are being made. Because of recombinant DNA technology and rapid DNA sequencing, a number of genes of influenza virus from a number of strains have been either completely or partially sequenced. Among these, the gene coding for hemagglutinin (HA) has been most intensively studied and the HA of one or more strains from each subtype (H1, H2, H3) has been completely sequenced. Other topics discussed include the question of drift and shift at the genomic level; the role of the capped host mRNA is the process of initiation of transcription; and the regulation of viral transcription. This volume also includes papers presented by the speakers of the plenary sessions and that of keynote speaker, Sir Charles Stuart-Harris as well as the selected papers presented in the poster sessions.

While viruses—the world’s most abundant biological entities—are not technically alive, they invade, replicate, and evolve within living cells. Michael Cordingley goes beyond our familiarity with infections to show how viruses spur evolutionary change in their hosts and shape global ecosystems, from ocean photosynthesis to drug-resistant bacteria.

With the advent of genetic engineering methods and improved biochemical tech niques, much has been learned about the replication of influenza viruses, their structure and their epidemiology. It appears that the time is ripe to review these efforts and to provide a molecular perspective of influenza virology. It is hoped that this book will stimulate our thinking, help us in designing new experiments, and possibly show avenues leading to the control of the diseases associated with influenza viruses. Peter Palese, New York, N. Y. August 1983 David W. Kingsbury, Memphis, Tenn. Contents List of Contributors. . . . . . . . . . . . . . . . . XV 1. The Evolution of Influenza Viral Genetics - A Perspective. By E. D. Kilbourne. . . . . . . . . . . . . . . . 1 I. Introduction. . . . . . . . . . . . . . . . . 1 II. The Development of Modern Influenza Viral Genetics 2 A. Early Evidence of Genetic Variation in the Laboratory 2 B. Application of Formal Genetic Techniques to Studies of Influenza Virus . . . . . . . 3 C. Genetic Markers. . . . . . . . . 3 D. Development of Plaquing Systems. . . 4 E. The Use of Conditional Lethal Mutants 5 F. New Approaches in Influenza Virus Genetics. 6 1. The Biochemical Identification of Viral Gene Products in the Unambiguous Definition of Viral Inheritance . . . 6 2. Mapping of the Influenza Virus Genome by Correlative Physico-Chemical and Biological Techniques. . . . . . 7 3. The Application of Molecular Biological Techniques to the Study of Viral Genetic Variation. . . . . . . . . 8 4. Oligonucleotide Mapping of Viral RNA's . . . . . . . 8 5. Contribution of Protein and RNA Sequencing to Influenza Viral Genetics-Intragenic Mapping . . . . . . . 8 III. Viral Genetics and the Understanding of Viral Virulence and Pathogenicity . . . . . . . . . . . . . . . . . . .