Virus Life in Diagrams

Hans-Wolfgang Ackermann, Laurent Berthiaume, Michel Tremblay

• Publisher: CRC Press
• Year: 2021
• ISBN:
  9781000465365
• Edition: 1
• Topic: Ciencias biológicas
• Subtopic: Microbiología

This atlas presents 233 virus diagrams selected for their scientific content, clarity, originality, and historic, didactic, and aesthetic value. Virus Life in Diagrams assembles the many diagrams of viral life cycles, particle assembly, and strategies of nucleic acid replication that are scattered throughout the literature. The diagrams cover vertebrate, invertebrate, plant, bacterial, fungal, and protozoal viruses, viroids, and prions. They offer a dynamic illustration of the time course of viral life cycles not available in photographs. They also offer speculative elements that project the possible results of future research, as well as historical documentation that shows the development of virology. This valuable reference book for virologists, microbiologists, molecular biologists, geneticists, and students in these areas is the first atlas to compile illustrations of viral morphogenesis in one complete source.

Chapter 1

INTRODUCTION

This book is a sequel to the Atlas of Virus Diagrams, published in 1995 and concerned with viral morphology.¹ Its aim is to assemble the many diagrams of viral life cycles, particle assembly, and strategies of nucleic acid replication that are scattered over the literature. As was its predecessor, this book is directed at teachers and students. The title reflects the fact that viruses are inert in the environment and come to life during their multiplication within living cells.

Virology makes extensive use of diagrams to illustrate particle morphology and morphogenesis, viral genetic and replication cycles, epidemiology and replication of viral diseases, and virological techniques. Their function is to integrate large numbers of data of different origin, from electron microscopy to amino acid composition and clinical observations, into a single picture or a sequence of related diagrams. Photographs and experimental data usually illustrate the state or activity of a virus at a given moment. Diagrams transcend this moment and are thus ideally suited to illustrate the time course of viral life cycles and the steps of viral nucleic acid replication. Some diagrams, intended to promote understanding and future research, contain speculative elements and some reflect personal views or interpretational errors of the day. Others are historical documents and time capsules illustrating the development of virology. For example, the nature of lysogeny is explained in a diagram from 1953, and a series of drawings from 1962, featuring virus-infected cells, shows that the cytopathic effects and general life cycles of many mammalian viruses were known at an early date. Finally, many diagrammatical representations of viral development are true artistic creations that deserve preservation in their own right.

The 233 diagrams in this book were selected from about 1000 drawings from over 50 periodicals and 150 books or monographs from the English, French, and German literature. Most diagrams were from a few core journals, notably Advances in Virus Research, Virology, Journal of Virology, and Journal of General Virology. Scientific content was the prime criterion for selection, followed by clarity and didactic value, originality of concept, esthetic appeal, and historic interest. Vertebrate viruses and the tailed bacteriophages T4 and λ were well illustrated in the literature, often with considerable detail. Representations of retrovirus and herpesvirus life cycles were particularly frequent, but many other, generally less known viruses were not illustrated at all. As a consequence, the diagrams in this book illustrate the morphogenesis and replication of only 30 virus families and six nonclassified “floating” genera. Plant viruses are clearly underrepresented and as many as 23 families and 15 “floating” genera of bacterial, plant, fungal, algal, or protozoal viruses are absent from this book. In plant viruses, this reflects the centering of research interests on applied rather than molecular microbiology. In fungal, algal, and protozoal viruses, this reflects lack of funding.

The diagrams are arranged according to the nature of viral nucleic acids and replication strategies rather than virus morphology or host range. The various types of viral nucleic acids, single-stranded or double-stranded RNA, have evolved many different strategies for replication, generally in relationship with their use of host mRNA. Consequently, the diagrams are grouped into five chapters corresponding to (i) a series of comparative diagrams, (ii) DNA viruses, (iii) viruses using reverse transcription, (iv) RNA viruses, and (v) miscellaneous entities including prions.

The comparative diagrams illustrate the properties of large groups such as enveloped or ssRNA viruses. A diagram on interferons is added because of its general nature. DNA viruses are subdivided into viruses with ssDNA (certain bacteriophages and parvoviruses), dsDNA viruses with cubic or helical symmetry, and dsDNA viruses with binary symmetry or tailed bacteriophages; this latter section is warranted because of the large number and diversity of diagrams available for these phages. Viruses using reverse transcription comprise DNA and RNA viruses of plants (badna- and caulimoviruses) and vertebrates (hepadna- and retroviruses). The chapter on RNA viruses includes sections on viruses with (+) sense and (−) sense ssRNA and viruses with dsDNA. The first two sections contain viruses with segmented and nonsegmented genomes. This arrangement brings out taxonomically important common properties. For example, regardless of morphology or host specificity, (+) strand RNA virus genomes code for RNA polymerases and replicate in strikingly similar ways, (−) sense RNA viruses are enveloped, (−) sense ssRNA and dsRNA viruses contain a viral RNA-dependent RNA polymerase, and dsRNA viruses have segmented genomes which all seem to be transcribed within viral particles. Similarly, one notes that several virus groups with dsDNA, namely adeno-, herpes-, and iridoviruses, resemble tailed phages in several aspects of replication and particle assembly.

Virus families and “floating” genera are arranged alphabetically within each section. Each family or single genus is characterized by a few key words and the introductory paragraph includes a short description of taxonomic status, particle morphology, host range, and major physiological features. In families illustrated more than once, diagrams are arranged from the general to the detailed, starting with cytopathic effects or whole life cycles and ending with the replication of nucleic acids. Except for retroviruses, there are few illustrations of genomic maps, translation, and regulation. The reasons are lack of space, due to the need to limit the number of pages of this book, and the uneven state of knowledge in virology, a few viruses being known in exquisite detail and the vast majority in outlines only. Virology has not yet reached the point where a coherent picture of translation can be given. Similarly, diagrams illustrating fine points of virology, for example the priming of DNA replication in tectiviruses or the biosynthesis of influenza virus hemagglutinin, have been left out because they were considered to be too detailed.

The diagrams were recorded with a Super Vista S-12 high-resolution scanner (UMAX Technologies, Freemont, CA; 600 × 1200 dpi). Many captions and some damaged diagrams, for example drawings recovered from microfilm, were restored and a number of foreign-language captions were translated into English. Legends represented particular problems. Some are extremely long in the original, extending over whole pages of small print. Others are so short that they are, taken out of context, not informative. We consider that each legend is an independent unit that has to be, in principle, understandable without consulting the original publication (although this may still be necessary in very complex diagrams). This situation required extensive rewriting. Many legends were shortened while still preserving their information content and others were completed from the accompanying text.

An overview of the state of virus classification, including the latest taxonomic changes, is presented in Chapter 2. Descriptions of individual taxa may be found in the periodical reports of the International Committee of Virology. An outline of viral multiplication, centering on mammalian viruses and regrettably short in information on viruses of fungi, algae, and protozoa, is given in Chapter 3. The diagrams are followed by an extensive glossary, warranted by a profusion of new terms or alternative meanings. Many frequently used terms, e.g., “capsid,” “core,” or “matrix,” have acquired several meanings; even the now famous term “provirus” not only applies to the latent integrated DNA of retrovirus genomes, but is also used to designate immature virus particles. Many definitions in the glossary are taken or derived from the virological dictionary of Hull, Brown, and Payne² and the recent Encyclopedia of Molecular Biology.³ Others have been devised by us.

Chapter 2

A SUMMARY OF VIRUS CLASSIFICATION

Viruses consist minimally of nucleic acid and a protein shell or capsid. The shell is of cubic or helical symmetry or, in tailed phages, a combination thereof (“binary symmetry”). Capsids with cubic symmetry are icosahedra or related bodies. In about one third of virus families, the capsid is surrounded by a lipid-containing envelope. A few exceptional types have an envelope and no capsid. The nucleic acid is single-stranded or double-stranded DNA or RNA, is linear or circular, and comprises one or several molecules (up to 12). All DNA viruses except polydnaviruses contain a single molecule of DNA. All RNA genomes except that of hepatitis deltavirus are linear. In some plant viruses, the individual segments of multipartite genomes are packaged into separate shells, constituting multicomponent systems.

The present edifice of virus classification is essentially the work of the International Committee on Taxonomy of Viruses or ICTV. It deve...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Acknowledgments
• The Authors
• Chapter 1 Introduction
• Chapter 2 A Summary of Virus Classification
• Chapter 3 The Replication Cycle
• Chapter 4 Comparative Diagrams
• Chapter 5 DNA Viruses
• Chapter 6 Viruses with Reverse Transcription
• Chapter 7 RNA Viruses
• Chapter 8 Miscellany
• Abbreviations and Units
• Glossary
• References
• Index