Virus Variability and Impact on Epidemiology and Control of Diseases E. Kurstak and A. Hossain I. INTRODUCTION An important number of virus infections and their epidemic developments demonstrate that ineffec tiveness of prevention measures is often due to the mutation rate and variability of viruses (Kurstak et al., 1984, 1987). The new human immunodeficiency retroviruses and old influenza viruses are only one among several examples of virus variation that prevent, or make very difficult. the production of reliable vaccines. It could be stated that the most important factor limiting the effectiveness of vaccines against virus infections is apparently virus variation. Not much is, how ever, known about the factors influencing and responsible for the dramatically diverse patterns of virus variability. II. MUTATION RATE AND VARIABILITY OF HUMAN AND ANIMAL VIRUSES Mutation is undoubtedly the primary source of variation, and several reports in the literature suggest that extreme variability of some viruses may be a consequence of an unusually high mutation rate (Holland et al., 1982; Domingo et al., 1985; Smith and Inglis, 1987). The mutation rate of a virus is defined as the probability that during a single replication of the virus genome a particular nucleotide position is altered through substitution, deletion, insertion. or recombination. Different techniques have been utilized to measure virus mutation rates, and these have been noted in the extent of application to different viruses.

The all new Concepts in Viral Pathogenesis III contains the widely praised format of presenting up-to-date information in pithy, easily read "mini-review" style and complements previous editions with contributions by leading international authorities on structure-function relationships, gene regulation, cell biology of viral infections, transgenic mice, expression of viral genes, retroviruses, and evolving concepts in viral diseases. Taken together, Volume I, II and III of Concepts in Viral Pathogenesis contain 145 unique chapters each representing the latest thinking in important areas of virology by the foremost investigators in the field. Clinicians, laboratory scientists, students, and others seeking authoritative overviews of current knowledge on the mechanism of viral diseases will welcome this valuable resource.

Providing both historical background and recent advances, this series reviews in-depth the biologic, molecular, immunologic, and patholic features of this facinating virus family. The current volume focuses on the avian and murine species which have generated novel insights into cancer, and the evolution of the retroviridae.

Is cancer a contagious disease? In the late nineteenth century this idea, and attending efforts to identify a cancer “germ,” inspired fear and ignited controversy. Yet speculation that cancer might be contagious also contained a kernel of hope that the strategies used against infectious diseases, especially vaccination, might be able to subdue this dread disease. Today, nearly one in six cancers are thought to have an infectious cause, but the path to that understanding was twisting and turbulent. ? A Contagious Cause is the first book to trace the century-long hunt for a human cancer virus in America, an effort whose scale exceeded that of the Human Genome Project. The government’s campaign merged the worlds of molecular biology, public health, and military planning in the name of translating laboratory discoveries into useful medical therapies. However, its expansion into biomedical research sparked fierce conflict. Many biologists dismissed the suggestion that research should be planned and the idea of curing cancer by a vaccine or any other means as unrealistic, if not dangerous. Although the American hunt was ultimately fruitless, this effort nonetheless profoundly shaped our understanding of life at its most fundamental levels. A Contagious Cause links laboratory and legislature as has rarely been done before, creating a new chapter in the histories of science and American politics.

A select group of highly renowned scientists - among them four Nobel Prize Winners - have been asked to summarize significant developments of their ownrecent research in the life sciences at a workshop organized on the occasionof the opening of the new Paul-Ehrlich-Institut in Langen near Frankfurt/ Main. They do this in a comparative fashion evaluating similar achievements in adjacent fields. Their intellectual state-of-the-art analysis and fascinating outlook on future perspectives provides exciting and stimulating reading. The authors address areas in virology, immunology, oncology and evolution. Intelligent design of vaccines and other immunologial drugs, virus evolution and viruses as nature's engineers, pathology of chronic autoimmune and central nervous system diseases and the biology of mammary cancer belong to the topics discussed. A book easy to read for scientists, doctors and students interested in rapidly developing fields in the life sciences.

The Fifth Report of the International Committee on Taxonomy of Viruses (ICTV), summarizes the proceedings and decisions reached by the ICTV at its meetings held at the International Congresses of Virology in Sendai (1984), Edmonton (1987) and Berlin (1990). This report has been organized in the same way as the previous ones (Wildy, 1971; Fenner, 1976; Matthews, 1979; 1982), yet it encompasses many more families and groups of viruses than previous reports, and it includes new tables, diagrams and keys. The officers and members of the ICTV study groups from 1984 to 1990 are listed, as the current ICTV statutes and rules of nomenclature. Information on the format for submission of new taxonomic proposals to the ICTV is also provided. Since the Fourth Report of the ICTV (1982), 19 new virus families and groups have been described. This report includes 2,430 viruses belonging to 73 families or groups, as well as virus satellites and viroids descriptions, but it does not include descriptions not approved by the ICTV. It now will be possible to publish such preliminary, and in some cases controversial, descriptions in the Virology Division pages of the Archives of Virology --this will allow virologists to carry on the kind of interim dialogue that is necessary for arriving at broad agreement on taxonomic matters.

Now in its Twelfth Edition, Diseases of Poultry continues its tradition of excellence as the definitive reference of poultry disease. Following the same user-friendly format, the book has been thoroughly updated to reflect the most current knowledge of avian pathology, including new coverage of genetic resistance to disease. Coverage is given to both common and uncommon diseases, and chapters are organized by disease type, including viral, bacterial, fungal, parasitic diseases as well as others, such as nutritional, developmental, metabolic, noninfectious diseases and toxins. Each disease section provides detailed coverage of history, etiology, pathobiology, diagnosis, and intervention strategies, as well as the economic and public health significance of each disease. With a host of international authors, Diseases of Poultry is a must-have resource for all veterinary pathologists, practitioners, agricultural managers and industry leaders involved in poultry health and production.

Significant recent advances in cell culture technology now permit a detailed biochemical and molecular analysis of differentiation in both normal and tumor cells. These studies are important in attempting to understand the complex factors involved in normal growth and development, as well as the abnormalities associated with carcinogenesis. Mechanisms of Differentiation, Volumes I and II, is comprised of review chapters addressing various topics of current interest in this important area of research. Topics discussed include genes controlling differentiation, changes in gene expression during differentiation, induction of differentiation, induction of differentiation as a mode of action of chemotherapeutic agents, and the effect of cell shape, growth factors and differentiation modulating agents on the differentiated cell phenotype. Mechanisms of Differentiation is valuable to researchers involved in differentiation and development, carcinogenesis, cell biology, chemotherapy, and immunology.