The Plant Viruses: Polyhedral Virions with Tripartite Genomes

ISBN-13: 9781468449396 / Angielski / Miękka / 2012 / 309 str.

R. I. B. Francki

Opis

It has been known for a long time that the majority of plant viruses contain RNA and in the past decade and a half it has been realized that many have genomes consisting of three molecules of single-stranded RNA with positive polarity. Among these are viruses belonging to four groups recognized by the International Committee for Virus Taxonomy: the Bromovirus and Cucumovirus groups whose genomes are encapsi dated in small icosahedral particles or the Ilarvirus and alfalfa mosaic virus groups with spheroidal or bacilliform particles. In addition to their tripartite genomes, these viruses share a number of other properties and it has been proposed that they should perhaps be grouped in a single virus family for which the name Tricornaviridae has been suggested, the tri indicating the tripartite nature of the genome, the co emphasizing the cooperation of the three genome parts required to initiate infection, and the rna indicating that the genome is composed of RNA. Viruses of this "family" are less uniform in their biological proper ties. A number of them are widespread, causing very destructive plant diseases. Viruses such as those of cucumber mosaic and alfalfa mosaic have very extensive host ranges and are responsible for serious crop losses in many parts of the world. Others such as prunus necrotic ringspot or prune dwarf viruses are more restricted in their host ranges but never theless infect important perennial hosts such as stone fruits and reduce productivity considerably."

Spis treści

1 The Viruses and Their Taxonomy.- I. Introduction.- II. Members of the Tricornaviridae.- A. Bromovirus Group.- B. Cucumovirus Group.- C. Ilarvirus Group.- D. Alfalfa Mosaic Virus Group.- III. Taxonomic Considerations.- A. Features Common to All Tricornaviridae.- B. Comparison of the Bromoviruses with the Cucumoviruses.- C. Comparison of AMV with the Ilarviruses.- D. Significance of Genome Primary Structure to Taxonomy.- IV. Conclusions.- References.- 2 Virus Particle Stability and Structure.- I. Introduction.- II. Atomic Resolution Structures of Spherical Viruses.- A. Icosahedral Symmetry of Protein Capsids.- B. Structures of TBSV, SBMV, and STNV.- III. Virus Descriptions and Structure.- A. Alfalfa Mosaic Virus.- B. Ilarviruses.- C. Bromoviruses.- D. Cucumoviruses.- References.- 3 Viral Genome Structure.- I. Introduction.- II. General Structure of Tripartite Genomes.- III. RNA Sequence and Gene Content.- A. Information Derived from RNAs That Have Been Completely Sequenced.- B. Proportion of Each RNA Containing Protein-Coding Regions.- C. Are There Overlapping Reading Frames on Viral RNAs? Are There Subgenomic RNAs Other than RNA 4?.- IV. Sequence and Structure of Viral RNAs.- A. 5’-Terminal Sequences.- B. Sequences Upstream from Initiating AUG.- C. 3’-Terminal Sequences and Structures.- D. Intercistronic Region of RNA 3.- E. Characterization of Viral RNAs by Hybridization Analysis.- V. Satellite RNAs of the Cucumoviruses.- References.- 4 Virus Multiplication.- I. Introduction.- II. Experimental Systems.- A. Whole Plants.- B. Protoplasts.- C. In Vitro Systems.- III. Virus Entry and Uncoating.- IV. Virus Replication.- A. Initial Translation.- B. Proteins Involved in Replication.- C. RNA Replication.- D. Further Translation Products.- E. Inhibitors.- F. Time Courses of Replication.- G. Joint Infections of Viruses and Virus Strains.- V. Assembly in Relation to Virus Replication.- VI. Cellular Location of RNA Replication.- VII. Cell-to-Cell Spread.- VIII. Conclusions.- References.- 5 Virus Genetics.- I. Introduction.- II. Analysis of Pseudorecombinants Constructed from Genome Parts of Naturally Occurring Virus Strains.- III. Analysis of Incomplete Infections.- IV. Analysis of Mutants.- A. Type of Mutants.- B. Determination of ts Character.- C. Spontaneous Mutations.- D. Stability of Mutants.- E. Induction of Mutations.- F. Selection of Mutants.- G. Reversion of Mutations.- H. Assignment of Mutations to RNA Components.- I. Complementation and Interference between Mutants with ts Defects and the Same RNA.- J. Viral Functions Affected by Mutations.- V. Summary and Prospects.- VI. Glossary of Mutants Cited in This Chapter.- References.- 6 Virus-Host Relationships: Symptomatological and Ultrastructural Aspects.- I. Introduction.- II. Effects of Virus Infection on Host Morphology and Cell Structure.- III. Symptomatology.- IV. Cytopathology.- A. Cucumovirus Group.- B. Bromovirus Group.- C. Ilarvirus Group.- D. Alfalfa Mosaic Virus.- V. Concluding Remarks.- References.- 7 Serology and Immunochemistry.- I. Introduction.- II. Immunological Techniques.- A. Problems with Immunization.- B. Serological Techniques.- III. Serological Relationships.- A. Relationships between Viruses.- B. Relationships between Virus Strains.- IV. Immunochemical Studies.- A. Current Status.- B. The Viruses as Model Tools for Immunochemical Research.- V. Taxonomic Implications.- VI. Concluding Remarks.- References.- 8 Virus Transmission.- I. Introduction.- II. Modes of Transmission.- A. Bromoviruses.- B. Alfalfa Mosaic Virus.- C. Cucumoviruses.- D. Ilarviruses.- III. Concluding Remarks.- References.- 9 Virus Epidemiology and Control.- I. Introduction.- II. Pollen-Borne Viruses.- A. Behavior of Insects and Patterns of Virus Spread.- B. The Epidemiology of Specific Diseases.- C. Perennial Hosts and Virus Survival.- D. Spread of Viruses within the Tissues of Woody Hosts.- III. Aphid-Borne Viruses.- A. Aphid Behavior.- B. Epidemiology of Aphid-Borne Viruses.- IV. Epidemiology of Bromoviruses.- V. Control.- A. Production of Virus-Free Plants.- B. Reduction of Virus Spread.- VI. Discussion.- References.