Combination Therapy against Multidrug Resistance explores the potential of combination therapy as an efficient strategy to combat multi-drug resistance. Multidrug resistance (MDR) occurs when microorganisms such as bacteria, fungi, viruses, and parasites are excessively exposed to antimicrobial drugs such as antibiotics, antifungals, or antivirals, and in response the microorganism undergoes mutations or develops different resistance mechanisms to combat the drug for its survival. MDR is becoming an increasingly serious problem in both developed and developing nations. Bacterial resistance to antibiotics has developed faster than the production of new antibiotics, making bacterial infections increasingly difficult to treat, and the same is true for a variety of other diseases. Combination therapy proves to be a promising strategy as it offers potential benefits such as a broad spectrum of efficacy, greater potency than the drugs used in monotherapy, improved safety and tolerability, and reduction in the number of resistant organisms. This book considers how combination therapy can be applied in multiple situations, including cancer, HIV, tuberculosis, fungal infections, and more. Combination Therapy Against Multidrug Resistance gathers the most relevant information on the prospects of combination therapy as a strategy to combat multridrug resistance and helping to motivate the industrial sector and government agencies to invest more in research and development of this strategy as a weapon to tackle the multidrug resistance problem. It will be useful to academics and researchers involved in the development of new antimicrobial or antiinfective agents and treatment strtategies to combat multidrug resistance. Clinicians and medical nurses working in the field of infection prevention and control (IPC) will also find the book relevant

SARS was the ?rst new plague of the twenty-?rst century. Within months, it spread worldwide from its "birthplace" in Guangdong Province, China, affecting over 8,000 people in 25 countries and territories across ?ve continents. SARS exposed the vulnerability of our modern globalised world to the spread of a new emerging infection. SARS (or a similar new emerging disease) could neither have spread so rapidly nor had such a great global impact even 50 years ago, and arguably, it was itself a product of our global inter-connectedness. Increasing af?uence and a demand for wild-game as exotic food led to the development of large trade of live animal and game animal markets where many species of wild and domestic animals were co-housed, providing the ideal opportunities for inter-species tra- mission of viruses and other microbes. Once such a virus jumped species and attacked humans, the increased human mobility allowed the virus the opportunity for rapid spread. An infected patient from Guangdong who stayed for one day at a hotel in Hong Kong led to the transmission of the disease to 16 other guests who travelled on to seed outbreaks of the disease in Toronto, Singapore, and Vietnam, as well as within Hong Kong itself. The virus exploited the practices used in modern intensive care of patients with severe respiratory disease and the weakness in infection control practices within our health care systems to cause outbreaks within hospitals, further amplifying the spread of the disease. Health-care itself has become a two-edged sword.

Bluetongue may be described as an acute insect borne disease of ruminants, manifested clinically in sheep by a catarrhal inflammation of the mucous mem branes of the digestive and respiratory systems and associated with degenerative changes in the skeletal musculature. The profound emaciation and weakness which follow the acute disease are responsible for a protracted convalescence and for serious economic losses due to diminished productivity. II. Historical During the early colonisation of Africa, susceptible Merino and other European breeds of sheep were introduced into the Cape, at first by the Dutch East India Company between 1652 and 1785 and again later in 1870. A report of the Cattle and Sheep Diseases Commission (1876) records the appearance of a serious febrile disease amongst these imported sheep in which both morbidity and mortality was high (cited by HENNING, 1949). HuTCHEON (1881) gave this disease the name of "Fever" or "Epizootic Catarrh," in order to distinguish it from other clinical conditions of a similar nature encountered amongst sheep. In the first com prehensive description of this clinical syndrome and its epizootiology HuTCHEON (1902) referred to it as "Malarial Catarrhal Fever of Sheep," a designation which was obviously influenced by the mistaken belief that an intracorpuscular parasite was the primary cause of the disease. More systematic studies were conducted by SPREULL (1902; 1905), who endeavoured to immunize sheep by the simultaneous inoculation of immune serum and infective blood."

It is hardly necessary to define the concept of receptors to readers of this series, but it should be born in mind that in several instances receptors are undefined entities, whose molecular details remain to be established. On the other hand the ligand, which reco izes the receptors, has been identified and characterized in most cases. The current interest in the structure and function of biological membranes gives great expectations that in the near future we may understand the details of ligand-receptor interaction. This interaction involves two defined steps: the first, usually referred to as recognition, is followed by the second step, transduction, in which the ligand-receptor interaction is translated by the cell into a biochemical action. The present two volumes which cover prokaryotic and eukaryotic virus receptors, have been published together in order to illustrate the specificity of virus receptor recognition which appears to be a guiding principle for both bacteria and higher cells. The identification and characterization of the receptors for phages of gram-negative bacteria has to a large extent relied on the genetic techniques available for these organisms. In a similar way the availability of genetic systems has also clarified the interrelationship between animal retrovirus receptors even if the molecular structure remains to be determined. The paucity of defined genetic systems may therefore explain part of our ignorance concerning the molecular details of virus receptors on human cells and possibly also on gram positive bacteria."

Praised forits clarity of presentation and accessibility, Introduction to Modern Virology has been a successful student text for over 30 years. It provides a broad introduction to virology, which includes the nature of viruses, the interaction of viruses with their hosts and the consequences of those interactions that lead to the diseases we see. This new edition contains a number of important changes and innovations including: * The consideration of immunology now covers two chapters, one on innate immunity and the other on adaptive immunity, reflecting the explosion in knowledge of viral interactions with these systems. * The coverage of vaccines and antivirals has been expanded and separated into two new chapters to reflect the importance of these approaches to prevention and treatment. * Virus infections in humans are considered in more detail with new chapters on viral hepatitis, influenza, vector-borne diseases, and exotic and emerging viral infections, complementing an updated chapter on HIV. * The final section includes three new chapters on the broader aspects of the influence of viruses on our lives, focussing on the economic impact of virus infections, the ways we can use viruses in clinical and other spheres, and the impact that viruses have on the planet and almost every aspect of our lives. A good basic understanding of viruses is important for generalists and specialists alike. The aim of this book is to make such understanding as accessible as possible, allowing students across the biosciences spectrum to improve their knowledge of these fascinating entities.

Using different viral models, molecular pathways regulated by viral genes and their role in the pathogenesis of infection are analyzed. The book also offers an update of known signaling pathways in apoptosis and their role in normal and infected cells. Special emphasis is given to molecular pathways underlying viral transformation and oncogenesis and how research in this area is opening opportunities in cancer therapy.

In 2020, an invisible germ-a virus-wholly upended our lives. We're most familiar with the viruses that give us colds or Covid-19. But viruses also cause a vast range of other diseases, including one disorder that makes people sprout branch-like growths as if they were trees. Viruses have been a part of our lives for so long that we are actually part virus: the human genome contains more DNA from viruses than our own genes. Meanwhile, scientists are discovering viruses everywhere they look: in the soil, in the ocean, even in deep caves miles underground. Fully revised and updated, with new illustrations and a new chapter about coronaviruses and the spread of Covid-19, this third edition of Carl Zimmer's A Planet of Viruses pulls back the veil on this hidden world. It presents the latest research on how viruses hold sway over our lives and our biosphere, how viruses helped give rise to the first life-forms, how viruses are producing new diseases, how we can harness viruses for our own ends, and how viruses will continue to control our fate as long as life endures

One hundred years ago, when Martinus W. Beijerinck in Delft and Friedrich Loeffler on Riems Island discovered a new class of infectious agents in plants and animals, a new discipline was born. This book, a compilation of papers written by well-recognized scientists, gives an impression of the early days, the pioneer period and the current state of virology. Recent developments and future perspectives of this discipline are sketched against a historic background. With contributions by A. Alcami, D. Baulcombe, F. Brown, L. W. Enquist, H. Feldmann, A. Garcia-Sastre, D. Griffiths, M. C. Horzinek, A. van Kammen, H.-D. Klenk, F. A. Murphy, T. Muster, R. O'Neill, P. Palese, C. Patience, R. Rott, H.- P. Schmiedebach, S. Schneider-Schaulies, G. L. Smith, J. A. Symons, Y. Takeuchi, V. ter Meulen, P. J. W. Venables, V. E. Volchkov, V. A. Volchkova, R. A. Weiss, W. Wittmann, H. Zheng

In Virus-Insect-Plant Interactions, the world's leading scientists discuss the latest breakthroughs in understanding the biological and ecological factors that define these complex transmission systems and how this knowledge might be used to our advantage in producing innovative, user and environmentally friendly approaches to controlling the spread of plant pathogens by insects. This is an invaluable reference work for researchers, teachers, and students. There are many quick-reference figures and tables, the contents pages include individual chapter abstracts, and each chapter ends with its own bibliography.
Key Features
* presents the most significant research breakthroughs of the past two decades
* contains eighteen chapters by forty-two world-renowned researchers
* invaluable reference work for researchers, teachers and students
* each chapter ends with its own bibliography
* contents pages of forematter include individual chapter abstracts
* contains many quick-reference figures and tables

Applied Plant Virology: Advances, Detection, and Antiviral Strategies provides an overview on recent developments and applications in the field of plant virology. The book begins with an introduction to important advances in plant virology, but then covers topics including techniques for assay detection and the diagnosis of plant viruses, the purification, isolation and characterization of plant viruses, the architecture of plant viruses, the replication of plant viruses, the physiology of virus-infected hosts, vectors of plant viruses, and the nomenclature and classification of plants. The book also discusses defense strategies by utilizing antiviral agents and management strategies of virus and viroid diseases. With contributions from an international collection of experts, this book presents a practical resource for plant virologists, plant pathologists, horticulturalists, agronomists, biotechnologists, academics and researchers interested in up-to-date technologies and information that advance the field of plant virology.

Rabies: Basis of the Disease and Its Management, Fourth Edition is an authoritative reference on the current status of rabies, including the virological, clinical, and public health aspects and management recommendations. Rabies remains one of the most important global public health problems worldwide. Although many important developments have been made over the past century to combat this disease, rabies has become a re-emergent infection in the resource-constrained countries. The Fourth Edition updates this classic reference with comprehensive coverage of the molecular virology, pathogenesis, immunology, vaccines, public health aspects, and epidemiology of rabies and is completely revised, with new chapters that will cover historical developments in rabies intervention strategies, the evolution of rabies virus, modeling rabies control, and on the strategy for rabies elimination. Rabies, Fourth Edition, provides physicians, veterinarians, public health advisors, epidemiologists, and research scientists with a single source for authoritative and up-to-date information on the diagnosis, treatment, control, and prevention of this fatal infectious virus.

Advances in molecular biology have enabled leaps forward in the determination of virus phylogenetic history. This detailed 1995 book results from the invitation to foremost experts to give essays on aspects of virus biology. Initial chapters cover impacts of viruses and their control. Further chapters detail genetic variation of viruses and the molecular basis of interrelations with hosts. This leads to discussions of interactions with the host at the population level, and their molecular basis and evolution. Seventeen chapters follow, by specialists on particular groups of viruses describing their impact, genetic origins, sources of variation, population genetics and interactions with hosts. Practical virologists will find the chapters on phylogenetic analysis techniques very useful. The adaptive nature of viruses makes this work highly relevant to evolutionists.

Positive-strand RNA viruses include the majority of the plant viruses, a number of insect viruses, and animal viruses, such as coronaviruses, togaviruses, flaviviruses, poliovirus, hepatitis C, and rhinoviruses. Works from more than 50 leading laboratories represent latest research on strategies for the control of virus diseases: molecular aspects of pathogenesis and virulence; genome replication and transcription; RNA recombination; RNA-protein interactions and host-virus interactions; protein expression and virion maturation; RNA replication; virus receptors; and virus structure and assembly. Highlights include analysis of the picornavirus IRES element, evidence for long term persistence of viral RNA in host cells, acquisition of new genes from the host and other viruses via copy-choice recombination, identification of molecular targets and use of structural and molecular biological studies for development of novel antiviral agents.

Rapid developments continue to take place in the research of viruses, the causative agents of infectious diseases in humans, animals, plants, invertebrates, protozoa, fungi, and bacteria. A still growing number of more than 30,000 viruses, virus strains, and subtypes are being tracked in various specialty laboratories and culture collections. In this situation of expansion and specialization, the International Committee on Taxonomy of Viruses was founded to establish, refine and maintain a universal virus taxonomy system giving information to virologists about the characteristics of the different groups of viruses. The Committee s Sixth Report includes one order, 71 families, 11 subfamilies, and 175 genera and more than 4,000 member viruses. On 600 printed pages large amounts of molecular biologic data, illustrated by micrographs and virion diagrams, gene maps and tables give a comprehensive overview and prove helpful in teaching, in diagnostics, in scholarly research, and in the practical areas of medicine, veterinary medicine, plant pathology, insect pest management, and biotechnology. ..". est une reference indispensable pour les chercheurs, les enseignants, les medecins ou les veterinaires mais aussi pour les etudiants et d une maniere generale pour toutes les personnes interessees par la virologie . Revue de Medecine Veterinaire ..". an excellent, well presented and informative volume. The report should be an essential reference volume for any department or organization involved in the study of viruses . Quarterly"

Among unconventional agents and unclassified viruses the contributions to this volume focused on prion-related diseases, with special emphasis on bovine spongiform encephalopathy and human spongiform encephalopathies, and Borna disease virus, an agent known since long time to be pathogenic for horses and sheep, which is now discussed as a potential pathogen for humans. Additionally, the volume contains articles about newly discovered viruses like porcine respiratory and reproductive syndrome virus and viruses that are classified only provisionally like African swine fever virus, hepatitis C and E viruses, or the arteriviruses.

Recombinant viruses provide an efficient mechanism for the transfer and expression of DNA in eukaryotic cells. First, the transfer of DNA by viral infection-utilizing specific cell surface receptors and cellular intern- ization mechanisms-occurs much more readily than DNA transfer via uptake induced by such physical methods as calcium phosphate coprecipitation or electroporation. Second, the novel strategies employed by the virus to express its own genes can then be "hijacked" in the recombinant virus to express the researcher's gene of interest The purpose of Practical Molecular Virology isthus to compile a coll- tion of readily repeatable gene transfer and expression methods from wo- ers expert in the use of a variety of recombinant viral vectors . These include those designed for the production of recombinant antigens, such as pol- virus and yeast Ty-VLPs; those giving very high levels of recombinant protein expression, for example, baculovirus, vaccinia virus, and SV40; and finally viral vectors used for efficient, stable gene transfer to eu otic cells, such as retroviruses and herpesviruses . The first chapter describes the viral life cycle for each virus, and explains how this can be adapted to allow construction of recombinant vectors. Subsequent chapters deal with methods for producing and char- terizing recombinant viruses . I make no apology for the hyperproliferation of chapters dealing with recombinant retroviral methods and applications, since I believe this is clearly proportional to the recent expansion of interest in these techniques.

This volume summarizes selected papers presented at two symposia convened in the fall of 1989. The papers include information on the molecular biology, antigenicity, diagnosis, epidemiology, clinical aspects, pathogenesis, vaccines and other aspects of haermorrhagic fever with renal syndrome and tick (tick-borne encephalitis, Congo-Crimean haemorrhagic fever, Duqbe, orbiviruses, orthomyxoviruses) and mosquito-borne (California serogroup, alphaviruses from Mongolia, sandfly fevers in Central Asia and Afghanistan) viruses. Although covering a wide range of subjects and perspectives, the book is intended to provide readers with an integrated view of the geographical distribution, properties and effects, recognition and prevention of infections with these and other viruses. Included are papers describing newly recognized viruses, virus diseases, foci, techniques for detection and diagnosis, and vaccines.

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.

We have attempted to provide a concise and up to date account of human viruses in the environment with attention to basic tools now available for monitoring viruses. We have aimed this introductory volume at young students, teachers and investigators in microbiology, virology, environmental engineering and health sciences. As the routes for virus dissemination become more varied, there is an enhanced potential for causing infection in humans. Improvement in the development of control strategies will alleviate the magnitude of viral pollution of the environment. This volume will introduce the reader to an area of science which of necessity must utilize a variety of disciplines. V.CHALAPATIRAO JOSEPH L. MELNICK v We humbly dedicate this volume to the cherished memory of our parents Contents Preface v 1 Introduction 1 References 9 2 Human enteric viruses in polluted water 10 Enteroviruses 10 Hepatitis A virus 11 Non-A, non-B hepatitis 12 Norwalk and Norwalk-like agents 12 Rotaviruses 13 Adenoviruses 13 Parvoviruses 14 Enteric viruses in the etiology of water-borne disease 14 Summary 16 References 16 3 Monitoring for viruses in wastewater and water 18 Why water should be monitored for viral contamination 18 Methods for monitoring viral contamination 19 Virus isolation from sewage, and surface and drinking water 25 Indicators for viruses 30 Standards for viruses in drinking water 32 Future developments in virus detection 33 Summary 38 References 39 4 Virus removal by treatment processes 41 Advanced waste treatment (tertiary treatment) 46 Disinfection 49 Summary 54 References 54

The study of viruses, or virology as it is now called, had its origin in 1892 when a Russian botanist, Iwanawsky, showed that sap from a tobacco plant with an infectious disease was still highly infectious after passage through a filter capable of retaining bacterial cells. From such humble beginnings the study of these 'filter-passing agents', or viruses, has developed into a separate science which rivals, if it does not excel, in importance the whole of bacteriology. The importance of viruses lies not only in the diseases they cause in every type of living organism, but also because of their intimate relationship with the living cell, in which alone they can reproduce. Their study has influenced the whole of biology by greatly increasing our knowledge of the gene, genetics, and molecular structure; there is also the possible connexion of viruses with human cancer, in view of the occurrence of many viral cancers in other animals. The book attempts to give a comprehensive but necessarily superficial survey of the subject as a whole and should help senior undergraduates and postgraduate students who wish to gain some knowledge of virology. Further information is available from the extensive bibliography.

1. 1 Historical development of molecular virology of effort on a limited number of phages, Viruses have occupied a central position in notably the Escherichia coli phages T2 and T4. molecular biology ever since its development as At the same time Lwoff and his colleagues were an independent discipline. Indeed, molecular studying phage A, a temperate phage of E. coli, biology itselflargely developed out of the work which was to lead to equally fundamental pioneer studies of Delbriick, Luria and Hershey, observations on the regulation of macro who realized, in the late 1930's, that bacterial molecular synthesis. viruses (bacteriophages, often abbreviated to The study of animal and plant viruses has its phages) had properties which made them origins in the latter half of the 19th century uniquely suitable as a model system for an and was largely initiated by workers in medical, attack on one of the then outstanding problems veterinary and agricultural disciplines. Many of of biology, the definition of the gene in their practical successes owe little to molecular physical and chemical terms. The favourable biology, stemming instead from those properties of these viruses include the rapidity approaches successful in combating other of their growth, their ease of assay, and the parasites, such as vector control and the availability of easily scored genetic markers. breeding of resistant varieties of plants."

**THE SUNDAY TIMES BESTSELLER | BBC RADIO 4 BOOK OF THE WEEK** Preventable tells the extraordinary story of COVID-19 and how global politics shape our health - from a world-leading expert and the pandemic's go-to science communicator Professor Devi Sridhar has risen to prominence for her vital roles in communicating science to the public and speaking truth to power. In Preventable she highlights lessons learned from outbreaks past and present in a narrative that traces the COVID-19 pandemic - including her personal experience as a scientist - and sets out a vision for how we can better protect ourselves from the inevitable health crises to come. In gripping and heartfelt prose, Sridhar exposes the varied realities of those affected (from the jailed doctor in Wuhan who sounded the alarm, and the bored passengers marooned on the Diamond Princess cruise ship, to the daily nightmares of exhausted healthcare workers), and puts you in the room with key decision makers at crucial moments (from over-confident heads of states and their hesitant scientific advisors, to the beleaguered leaders of global health organisations). Sridhar vibrantly conveys the twists and turns of a plot that saw: deadlier variants emerge (contrary to the predictions of social media pundits who argued it would mutate to a milder form); the Pyrrhic victory in many countries of the false narrative of health versus the economy (those countries which controlled the virus, like Taiwan and Denmark, had a steadier recovery); countries with weak health systems like Senegal and Vietnam fare better than countries like the US and UK (which were consistently ranked as the most prepared); and the quickest development of game-changing vaccines in history (and their unfair distribution). Combining science, politics, ethics and economics, this definitive book dissects the global structures that determine our fate, and reveals the deep-seated economic and social inequalities at their heart - it will challenge, outrage and inspire. 'A brutally compelling reminder that if voices like Devi's had been listened to, so many more could have lived' OWEN JONES 'One of the most brilliant scientists in the world who has been proven consistently right in this crisis' PIERS MORGAN 'Excellent . . . Fair, clear and compelling' NICOLA STURGEON 'Those who have found Professor Devi Sridhar's expertise and calm advice invaluable since the arrival of Covid-19 will be glad to know that she has written Preventable' RACHEL COOKE, Guardian, Non-fiction to look out for in 2022

'Lucid, calm, informed, directly helpful in trying to think about where we are now... The literature of the time after begins here' Evening Standard 'Taking a breather from bewildering statistics and terrible tales of contagion to read Giordano's book was a jolt of brevity and simplicity... It takes concepts that have been dancing away in our minds, just out of reach, and lines them up neatly' The Times 'Potent and original' Sunday Times 'In one short hour, in the midst of this difficult moment, Giordano reinforced my sense of hope in humanity, in the one and the many' Philippe Sands, author of East West Street and The Rat Line The Covid-19 pandemic is the most significant health emergency of our time. Writing from Italy in lockdown, physicist and novelist Paolo Giordano explains how disease spreads in our interconnected world: why it matters how it impacts us how we must react Expanding his focus to include other forms of contagion - from the environmental crisis to fake news and xenophobia - Giordano shows us not just how the coronavirus crisis got so bad so quickly, but also how we can work together to create change. Paolo Giordano is a physicist and the author of four bestselling novels. His article 'The Mathematics of Contagion' - published in Italy at the beginning of the coronavirus emergency - was shared more than 4 million times and helped shift public opinion in the early stages of the epidemic.

Science doesn't speak for itself. Neck-deep in work that can be messy and confounding and naive in the ways of public communication, scientists are often unable to package their insights into the neat narratives that the public requires. Enter celebrities, advocates, lobbyists, and the funders behind them, who take advantage of scientists' reluctance to provide easy answers, flooding the media with misleading or incorrect claims about health risks. Amid this onslaught of spurious information, Americans are more confused than ever about what's good for them and what isn't. In Bad Advice, Paul A. Offit shares hard-earned wisdom on the dos and don'ts of battling misinformation. For the past twenty years, Offit has been on the front lines in the fight for sound science and public heath. Stepping into the media spotlight as few scientists have done-such as being one of the first to speak out against conspiracy theories linking vaccines to autism-he found himself in the crosshairs of powerful groups intent on promoting pseudoscience. Bad Advice discusses science and its adversaries: not just the manias stoked by slick charlatans and their miracle cures but also corrosive, dangerous ideologies such as Holocaust and climate-change denial. Written with wit and passion, Offit's often humorous guide to taking on quack experts and self-appointed activists is a must-read for any American disturbed by the uptick in politicized attacks on science.

Approximately eight percent of our DNA contains retroviral sequences that are millions of years old. Through engaging stories of scientific discovery, Anna Marie Skalka explains our evolving knowledge of these ancient denizens of the biosphere and how this understanding has significantly advanced research in genetic engineering, gene delivery systems, and precision medicine. Discovering Retroviruses begins with the pioneer scientists who first encountered these RNA-containing viruses and solved the mystery of their reproduction. Like other viruses, retroviruses invade the cells of a host organism to reproduce. What makes them "retro" is a unique process of genetic information transfer. Instead of transcribing DNA into RNA as all living cells do, they transcribe their RNA into DNA. This viral DNA is then spliced into the host's genome, where the cell's synthetic machinery is co-opted to make new virus particles. The 100,000 pieces of retroviral DNA in the human genome are remnants from multiple invasions of our ancestors' "germline" cells-the cells that allow a host organism to reproduce. Most of these bits of retroviral DNA are degenerated fossils, but some have been exploited during evolution, with profound effects on our physiology. Some present-day circulating retroviruses cause cancers in humans and other animals. Others, like HIV, cause severe immunodeficiencies. But retroviruses also hold clues to innovative approaches that can prevent and treat these diseases. In laboratories around the world, retroviruses continue to shed light on future possibilities that are anything but "retro."