Fenner's Veterinary Virology

N. James Maclachlan, Edward J Dubovi

• Publisher: Academic Press
• Year: 2010
• eBook ISBN: 9780123751591
• Edition: 4
• Topic: Medicine
• Subtopic: Veterinary Medicine

Fenner's Veterinary, Virology, Fourth Edition, is the long awaited new edition of Veterinary Virology, 3e, which was published in 1999. Fully revised and updated by the new author team, part I presents the fundamental principles of virology related to animal infection and disease, and part II addresses the clinical features, pathogenesis, diagnosis, epidemiology and prevention of individual diseases. New to this Edition- New author team - one main author to ensure that the book reads like an authored book but with the benefit of using experts to contribute to specific topics- Text has been refocused - part I has been condensed and where appropriate incorporated into part II to make it more user friendly- The number of figures have been increased and are now in full color- Fully revised and updated to include the latest information in the field of veterinary virology- Beautifully illustrated color figures throughout- Organized and current information provided by an expert team of authors

Part I

The Principles of Veterinary and Zoonotic Virology

Chapter 1 The Nature of Viruses

Chapter 2 Virus Replication

Chapter 3 Pathogenesis of Viral Infections and Diseases

Chapter 4 Antiviral Immunity and Prophylaxis

Chapter 5 Laboratory Diagnosis of Viral Infections

Chapter 6 Epidemiology and Control of Viral Diseases

Chapter 1

The Nature of Viruses

Chapter Contents

Introduction: A Brief History of Animal Virology

Characteristics of Viruses

Chemical Composition of the Virion

Viral Nucleic Acids in the Virion

Viral Proteins in the Virion

Viral Membrane Lipids

Viral Morphology

Virion Structure

Virion Symmetry

Viral Taxonomy

Introduction: A Brief History of Animal Virology

The history of human development has been shaped by at least three major recurring elements: (1) environmental changes; (2) human conflicts; (3) infectious diseases. With regard to infectious diseases, the impact has been not only directly on the human population, but also on the food supply. The origins of veterinary medicine are rooted in efforts to maintain the health of animals for food and fiber production, and animals essential for work-related activities. Control of animal disease outbreaks was not possible until the pioneering work of the late 19th century that linked microbes to specific diseases of plants and animals. Many attribute the beginning of virology with the work of Ivanofsky and Beijerinck (1892–1898) on the transmission of tobacco mosaic virus. Both scientists were able to show the transmission of the agent causing disease in tobacco plants using fluids that passed through filters that retained bacteria. Beijerinck also noted that the filterable agent could regain its “strength” from diluted material, but only if it were put back into the tobacco plants. The concept of a replicating entity rather than a chemical or toxin had its genesis with these astute observations. The era of veterinary virology had its beginning virtually at the same time as Beijerinck was characterizing tobacco mosaic virus transmission. Loeffler and Frosch (1898) applied the filtration criteria to a disease in cattle that later would be known as foot and mouth disease. Repeated passage of the filtrate into susceptible animals with the reproduction of acute disease firmly established the “contagious” nature of the filtrate and provided more evidence for a process that was inconsistent with toxic substances. These early studies provided the essential operational definition of viruses as filterable agents until chemical and physical studies revealed the structural basis of viruses nearly 40 years later.

In the early 20th century, use of the filtration criteria saw the association of many acute animal diseases with what were to be defined as viral infections: African horse sickness, fowl plague (high pathogenicity avian influenza), rabies, canine distemper, equine infectious anemia, rinderpest, and classical swine fever (hog cholera) (Table 1.1). In 1911, Rous discovered the first virus that could produce neoplasia (tumors), and for this discovery he was awarded a Nobel Prize. This early phase of virology was one of skepticism and uncertainty because of the limited tools available to define the filterable agents. Even with filtration, there were differences among the agents as to their size as defined by filter retention. Some agents were inactivated with organic solvents, whereas others were resistant. For equine infectious anemia, the acute and chronic forms of the disease were perplexing and an unresolved conundrum. These types of apparent inconsistencies made it difficult to establish a unifying concept for the filterable agents. For research on animal diseases, early workers were restricted to using animal inoculation in order to assess the impact of any treatment on any putative disease causing agent. For equine and bovine disease work, the logistics could be daunting. Help in providing definition to filterable agents came from the discovery of viruses that infected bacteria. Twort in 1915 detected the existence of a filterable agent that could kill bacteria. Like its plant and animal counterparts, the strength of a dilute solution of the bacterial virus could be regained by inoculating new cultures of bacteria. Felix d’Herelle also noted the killing of bacteria by an agent that he called “bacteriophage.” He defined the plaque assay for quantitating bacteriophage, a technique that became a keystone for defining the properties of viruses and for the studies that became the basis of virus genetics.

Table 1.1

Selected Moments in the History of Virology

Year	Investigator(s)	Event
1892	Ivanofsky	Identification of tobacco mosaic virus as filterable agent
1898	Loeffler, Frosch	Foot-and-mouth disease caused by filterable agent
1898	Sanarelli	Myxoma virus
1900	Reed	Yellow fever virus
1900	Mcfadyean, Theiler	African horse sickness virus
1901	Centanni, Lode, Gruber	Fowl plague virus (avian influenza virus)
1902	Nicolle, Adil-Bey	Rinderpest virus
1902	Spruell, Theiler	Bluetongue virus
1902	Aujeszky	Pseudorabies virus
1903	Remlinger, Riffat-Bay	Rabies virus
1903	DeSchweinitz, Dorset	Hog cholera virus (classical swine fever virus)
1904	Carré, Vallée	Equine infectious anemia virus
1905	Spreull	Insect transmission of bluetongue virus
1905	Carré	Canine distemper virus
1908	Ellermann, Bang	Avian leukemia virus
1909	Landsteiner, Popper	Poliovirus
1911	Rous	Rous sarcoma virus—first tumor virus
1915	Twort, d’Herelle	Bacterial viruses
1917	d’Herelle	Development of the plaque assay
1927	Doyle	Newcastle disease virus
1928	Verge, Christofornoni Seifried, Krembs	Feline parvovirus (feline panleukopenia virus)
1930	Green	Fox encephalitis (canine adenovirus 1)
1931	Shope	Swine influenza virus
1931	Woodruff, Goodpasture	Embryonated eggs for virus propagation
1933	Dimmock, Edwards	Viral etiology for equine abortions
1933	Andrewes, Laidlaw, Smith	First isolation of human influenza virus
1933	Shope	Swine natural host of pseudorabies
1933	Bushnell, Brandly	Avian bronchitis virus
1935	Stanley	Tobacco mosaic virus (TMV) crystallized; protein nature of viruses confirmed
1938	Kausche, Ankuch, Ruska	First electron microscopy pictures—TMV
1939	Ellis, Delbruck	One step growth curve—bacteriophage
1946	Olafson, MacCallum, Fox	Bovine viral diarrhea virus
1948	Sanford, Earle, Likely	Culture of isolated mammalian cells
1952	Dulbecco, Vogt	Plaque assay for first animal virus—poliovirus
1956	Madin, York, McKercher	Isolation of bovine herpesvirus 1
1957	Isaacs, Lindemann	Discovery of interferon
1958	Horne, Brenner	Development of negative-stain electron microscopy
1961	Becker	First isolation of avian influenza virus from wild bird reservoir
1963	Plummer, Waterson	Equine abortion virus=herpesvirus
1970	Temin, Baltimore	Discovery of reverse transcriptase
1978	Carmichael, Appel, Scott	Canine parvovirus 2
1979	World Health Organization	WHO declares smallpox eradicated
1981	Pedersen	Feline coronavirus
1981	Baltimore	First infectious clone of an RNA virus
1983	Montagnier, Barre-Sinoussi, Gallo	Discovery of human immunodeficiency virus
1987	Pedersen	Feline immunodeficiency virus
1991	Wensvoort, Terpstra	Isolation of porcine reproductive and respiratory syndrome virus (PRRSV)
1994	Murray	Hendra virus isolated
1999		West Nile virus enters North America
2002		SARS outbreak
2005	Palase, Garcia-Sastre, Tumpey, Taubenberger	Reconstruction of the 1918 pandemic influenza virus
2007		End of vaccination program for rinderpest
2011?		Declaration of the eradication of rinderpest

The initial studies on tobacco mosaic virus led to further understanding of “filterable agents”—namely viruses. Specifically, the high concentration of virus produced in infected tobacco plants permitted the chemical and physical characterization of the infectious material. By the early 1930s, there was evidence that the agent infecting tobacco plants was composed of protein, and that antibodies produced in rabbits could neutralize the virus. The tobacco mosaic virus was crystallized in 1935, and in 1939 the first electron micrograph of a virus was recorded. The particulate nature of viruses was now an established fact. A further advance in animal virology was the use of embryonated eggs for culturing virus in 1931. In the same year, Shope identified influenza virus in swine; in 1933, influenza virus was isolated from human cases of the infection. The identification of the strain H1N1 in swine might be considered the first “emerging” disease in animals—that is, a virus crossing a species barrier and maintaining itself as an agent of disease in the new species. In an attempt to move away from large-animal experimentation, and to provide model systems for human diseases such as influenza, mice and rats became important tools for studying animal viruses. Thus we had the birth of laboratory animal medicine programs that have become the essential backbone of biomedical research.

The decade 1938–1948 saw major advances by Ellis, Delbruck and Luria in the use of bacteriophage to probe the mechanism of inheritance of phenotypic traits of these bacterial viruses. Advances in understanding the properties of viruses progressed much more rapidly with bacterial viruses, because the work could be done in artificial media, without any requirement for laborious and time-consuming propagation of viruses in either animals or plants. A key concept in virus replication, namely the latent period, was defined using one-step growth curve experiments with bacteriophage. This observation of the loss of infectivity for a period after the initiation of the infection directed research to define the mode of replication of viruses as totally distinct from that of all other replicating entities. Animal virus studies made a dramatic shift in emphasis with the development of reliable in-vitro animal cell cultures (1948–1955). As a result of intensive efforts to control poliovirus infections, single cell culture procedures were defined, cell culture media were standardized, a human cell line was developed, and growth of poliovirus in a non-neuronal cell demonstrated. These advances all permitted the development of a plaque assay for poliovirus 35 years after the concept was defined for bacteriophage. All the basic studies on animal viruses that were hindered by the necessity to work in animal systems were now possible, and the principles established for bacteriophage could be explored for animal viruses. The cell culture era of animal virology had begun.

The advances in virology driven by human disease control efforts were directly applicable to animal virology. Bovine viral diarrhea virus was identified as a new disease-causing agent in cattle in 1946 and by the late 1950s was considered the most economically important disease of cattle in the United States. Cell culture procedures permitted isolation of the virus and the production of a vaccine by the early 1960s. Influenza virus was detected for the first time in wild birds in 1961, which led to the identification of water fowl and shore birds as the natural reservoir of influenza A viruses. An apparent cross-species incursion of a feline parvovirus variant produced the worldwide epizootic of canine parvovirus in the late 1970s. Again, standard in-vitro cell culture procedures identified the new agent and soon enabled the production of an effective vaccine. The entire arterivirus family (Arteriviridae) was identified in the cell culture era of virology—specifically, equine arteritis virus (1953), lactate dehydrogenase-elevating virus (1960), simian hemorrhagic fever virus (1964), and porcine reproductive and respiratory syndrome virus (1991). The discovery of human immunodeficiency virus (HIV) in 1983 attracted global attention, but the identification of simian immunodeficiency virus shortly thereafter may ultimately be of equal importance to the eventual control of human HIV infection. The primate system provided the animal models for studies of pathogenesis and vaccine development, and the existence of the simian virus in Old World primates provided the link to the origin of HIV as a cross-species (species jumper) infection.

The beginnings of the molecular era of virology reside in the late 1970s and early 1980s. Although not related to virology, the development of the polymerase chain reaction (PCR) in 1983 was to have an impact on virology as has no other technique to date. Cloning of nucleic acid sequences led to the first infectious molecular clone of a virus (poliovirus) in 1981. The impact of molecular techniques on virus detection and diagnostics was demonstrated with the identification of hepatitis C virus by molecular means without isolation (in-vitro culture of the virus). Viruses that could not be easily cultured in vitro—such as papillomaviruses, noroviruses, rotaviruses, and certain nidoviruses—could now be characterized and routinely detected by tests at the molecular level. A remarkably impressive feat spear-headed by Jeffrey Taubenberger was the molecular reconstruction of an infectious virus from RNA fragments representing the pandemic 1918 influenza A virus. Dreams of recreating extinct animals by molecular techniques may be farfetched, but the possibility exists for determining the early precursors of currently circulating viruses. Rapid and inexpensive nucleotide sequencing strategies are again redefining virology, and whole genomic sequencing is likely to replace less exact procedures for identifying and characterizing virus isolates. Metagenomic analyses of water and soil samples have i...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Dedication
• Contributors
• Acknowledgments
• Part I: The Principles of Veterinary and Zoonotic Virology
• Part II: Veterinary and Zoonotic Viruses
• Index