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.

First edition published in 2002. Second edition published in 2008.

This comprehensive account of the human herpesviruses provides an encyclopedic overview of their basic virology and clinical manifestations. This group of viruses includes human simplex type 1 and 2, Epstein–Barr virus, Kaposi's Sarcoma-associated herpesvirus, cytomegalovirus, HHV6A, 6B and 7, and varicella-zoster virus. The viral diseases and cancers they cause are significant and often recurrent. Their prevalence in the developed world accounts for a major burden of disease, and as a result there is a great deal of research into the pathophysiology of infection and immunobiology. Another important area covered within this volume concerns antiviral therapy and the development of vaccines. All these aspects are covered in depth, both scientifically and in terms of clinical guidelines for patient care. The text is illustrated generously throughout and is fully referenced to the latest research and developments.

Published since 1953, Advances in Virus Research covers a diverse range of in-depth reviews providing a valuable overview of the current field of virology. In 2004, the Institute for Scientific Information released figures showing that the series has an Impact Factor of 2.576, with a half-life of 7.1 years, placing it 11th in the highly competitive category of Virology.* Edited by an experienced plant pathologist who has over 50 years experience in plant virus epidemiology* Covers topics such as Evolutionary epidemiology of plant virus disease, The control of tropical plant virus diseases, and Control of plant virus diseases* A valuable resource for students and researchers alike

This book provides a comprehensive look at the field of plant virus evolution. It is the first book ever published on the topic. Individual chapters, written by experts in the field, cover plant virus ecology, emerging viruses, plant viruses that integrate into the host genome, population biology, evolutionary mechanisms and appropriate methods for analysis. It covers RNA viruses, DNA viruses, pararetroviruses and viroids, and presents a number of thought-provoking ideas.

Viral respiratory tract infections are important and common causes of morbidity and mortality worldwide. In the past two decades, several novel viral respiratory infections have emerged with epidemic potential that threaten global health security. This Monograph aims to provide an up-to-date and comprehensive overview of severe acute respiratory syndrome, Middle East respiratory syndrome and other viral respiratory infections, including seasonal influenza, avian influenza, respiratory syncytial virus and human rhinovirus, through six chapters written by authoritative experts from around the globe.

This book will serve as a primer for both laboratory and field scientists who are shaping the emerging field of molecular epidemiology. Molecular epidemiology utilizes the same paradigm as traditional epidemiology but uses biological markers to identify exposure, disease or susceptibility. Schulte and Perera present the epidemiologic methods pertinent to biological markers. The book is also designed to enumerate the considerations necessary for valid field research and provide a resource on the salient and subtle features of biological indicators.

also occurs. New outbreaks of yellow fever have occurred in Colombia and Trinidad and new outbreaks of rift valley fever have occurred in Egypt. Chapter 6, Arenaviruses: The biochemical and physical properties have now been clar ified, and they show a remarkable uniformity in the various viruses constituting the group. The possibility that prenatal infection with LCM may result in hydrocephalus and chorioretinitis has been raised. Serologic surveys have suggested the existence of Lassa virus infection in Guinea, Central African Empire, Mali, Senegal, Cameroon, and Benin, in addition to earlier identification in Nigeria, Liberia, and Sierra Leone. Chapter 7, Coronaviruses: New studies have confirmed the important role of these viruses in common respiratory illnesses of children and adults. The viruses are now known to contain a single positive strand of RNA. About 50% of corona virus infections result in clinical illness. About 5% of common colds are caused by strain DC 43 in winter. Chapter 8, Cytomegalovirus: Sections on pathogenesis of CMV in relation to organ transplantation and mononucleosis, as well as sections on the risk and features of con genital infection and disease, have been expanded. There are encouraging preliminary results with a live CMV vaccine, but the questions of viral persistence and oncogenicity require further evaluation.

New viral diseases are emerging continuously. Viruses adapt to new environments at astounding rates. Genetic variability of viruses jeopardizes vaccine efficacy. For many viruses mutants resistant to antiviral agents or host immune responses arise readily, for example, with HIV and influenza. These variations are all of utmost importance for human and animal health as they have prevented us from controlling these epidemic pathogens. This book focuses on the mechanisms that viruses use to evolve, survive and cause disease in their hosts. Covering human, animal, plant and bacterial viruses, it provides both the basic foundations for the evolutionary dynamics of viruses and specific examples of emerging diseases. - NEW - methods to establish relationships among viruses and the mechanisms that affect virus evolution - UNIQUE - combines theoretical concepts in evolution with detailed analyses of the evolution of important virus groups - SPECIFIC - Bacterial, plant, animal and human viruses are compared regarding their interation with their hosts

In the past half century, deadly disease outbreaks caused by novel viruses of animal origin - Nipah virus in Malaysia, Hendra virus in Australia, Hantavirus in the United States, Ebola virus in Africa, along with HIV (human immunodeficiency virus), several influenza subtypes, and the SARS (sudden acute respiratory syndrome) and MERS (Middle East respiratory syndrome) coronaviruses - have underscored the urgency of understanding factors influencing viral disease emergence and spread. Emerging Viral Diseases is the summary of a public workshop hosted in March 2014 to examine factors driving the appearance, establishment, and spread of emerging, re-emerging and novel viral diseases; the global health and economic impacts of recently emerging and novel viral diseases in humans; and the scientific and policy approaches to improving domestic and international capacity to detect and respond to global outbreaks of infectious disease. This report is a record of the presentations and discussion of the event.