Viral Genomes: molecular structure, diversity, gene expression mechanisms and host-virus interactions

ML GARCÍA & V ROMANOWSKI

InTech

Año: 2011 p. 304

979-953-307-045-1

Viral Genomes: molecular structure, diversity, gene expression mechanisms and host-virus interactionsShort descriptionViruses are small infectious agents that can replicate only inside the living cells of susceptible organisms. The understanding of the molecular events underlying the infectious process has been of central interest to improve strategies aimed at combating viral diseases of medical, veterinary and agricultural importance. Some of the viruses cause dreadful diseases, while others are also of interest as tools for gene transduction and expression and in non-poluting insect pest management strategies. The contributions in this book provide the reader with a perspective on the wide spectrum of virus-host systems. They are organized in sections based on the major topics covered: viral genomes organization, regulation of replication and gene expression, genome diversity and evolution, virus-host interactions, including clinically relevant features. The chapters also cover a wide range of technical approaches, including high throughput methods to assess genome variation or stability. This book shoul appeal all those interested in fundamental and applied aspects of virology.   PrefaceViral genomes are diverse in size and molecular structure (www.ictvdb.org). The bacteriophage MS2 genome is one of the smallest known; it encodes just four genes: maturation protein (A-protein), coat protein, replicase protein, and lysis. However, the expression of these proteins depends upon a complex interplay between translation and RNA secondary structure. It was the first fully sequenced viral genome (1): it took more than five years to determine the 3,569 nucleotides long single-stranded RNA of MS2 phage (1976). A year later the PhyX174 circular single-stranded DNA genome of 5,386 nucleotides , encoding 11proteins, was published (2). These two genomes were the first to be determined in scientific history. It has been a long way since these fabulous achievements of the early years molecular biology. Long before the advent of recombinant DNA technology, viruses (having a discrete number of genes) were indeed the first tools at hand to explore the mechanisms of genome replication and gene expression.Several leaps in sequencing strategies and technological advances (a blend of chemistry, enzymology, robotics and computer sciences) have increased our potential to molecularly describe new viral genomes in virtually no-time. Advances in molecular cloning and cell biology  This book compiles chapters written by experts on diferent aspects of selected viruses with DNA and RNA genomes that are pathogens for humans, other animals and plants. They represent just a sample of the smallest genomes (ranging from several thousands to hundreds of thousands nucleotides) that “come to life” when they succeed infecting a susceptible host cell. The molecular structures of viral genomes are as diverse as the molecularly exquisite alternatives of interactions with their host targets. The different chapters visit fundamental concepts of contemporary Virology. Although many edges of viral biology touch upon several aspects in an intertwigned manner (genomics, cell biology, pathogenesis, etc.), the chapters have been arranged in sections according to the main issues raised in each of them. Section 1 deals with the organization of large viral dsDNA genomes and also smaller ssRNA (monopartite and segmented) genomes. Bioinformatic analyses shed light on the potential function of yet unknown gene products and the evolutionary history of viral families. This information is complemented with experimental data on morphology, gene expression, pathology and viral population structure (quasispecies).Section 2 addresses mechanisms that affect regulation of replication and gene expression in viral RNA and DNA genomes (translational frameshifting signals, RNA structures that affect recombination, genome packaging, etc., protein-DNA interactions that affect viral and cellular genes transcription).A new generation sequencing technologies, enzymatic amplification of specific nucleotide sequence targets, and nucleic acid hybridization analyses in diferent types of platforms are some of the tools that revolutionized the study of fundamental aspects of Virology and also yielded practical applications such as assessing live attenuated virus vaccine stability. These issues are explored in Section 3. Finally, Section 4 explores some aspects of virus-host interactions that impact on tissue tropism, virulence, pathogenesis and the development of vaccines and therapeutic strategies.The editors wish to thank the authors for their contributions as well as the publishing team for their expert work and dedication. Profs. María Laura García & Víctor RomanowskiInstituto de Biotecnología y Biología Molecular(IBBM, CONICET-UNLP)Facultad de Ciencias ExactasUniversidad Nacional de La PlataArgentinaReferences:(1)     Fiers W, Contreras R, Duerinck F, Haegeman G, Iserentant D, Merregaert J, Min Jou W, Molemans F, Raeymaekers A, Van den Berghe A, Volckaert G, Ysebaert M. (1976). Complete nucleotide sequence of bacteriophage MS2 RNA: primary and secondary structure of the replicase gene. Nature 260 (5551):500-507. (2)     Sanger F, Air GM, Barrell BG, Brown NL, Coulson AR, Fiddes CA, Hutchison CA, Slocombe PM, Smith M (1977). Nucleotide sequence of bacteriophage phi X174 DNA. Nature 265 (5596): 687–695.