Encyclopedia of Food Sciences and Nutrition,6 Volume Set Vincent K. Greenwel

Virology is a fascinating and rapidly developing subject, and is worthy of study purely because viruses are interesting. There is a continuant need for trained virologists, and it is hoped that his book will play a small role to fulfill this need. A major branch of virology is virus classification. Viruses can be classified according to the host cell they infect: animal viruses, plant viruses, fungal viruses, and bacteriophages (viruses infecting bacteria, which include the most complex viruses). Another classification uses the geometrical shape of their capsid (often a helix or an icosahedron) or the virus's structure (e.g. presence or absence of a lipid envelope). Viruses range in size from about 30 nm to about 450 nm, which means that most of them cannot be seen with light microscopes. The shape and structure of viruses can be studied with electron microscopy, with NMR spectroscopy, and most importantly with X-ray crystallography. Virology is the study of viruses and virus like agents: their structure, classification and evolution, their ways to infect and exploit cells for virus reproduction, the diseases they cause, the techniques to isolate and culture them, and their use in research and therapy. Virology is often considered a part of microbiology or of pathology. Viruses can be spread through various ways, such as inhalation, swallowing, insect bites, sexual transmission, and contaminated blood transfusion. The most common outcome of a viral infection is host cell death (virulent infection). In contrast, some viruses can stay inside the host cell for years without causing any harmful effect (latent infection). In addition, viruses that undergo budding are released one at a time, causing persistent infection. This book provides the entire basic information required for the beginner of virology. All types of viruses including subviral agents, viroids and prions are dealt in an orderly manner with profuse illustrations. A comprehensive and update account of principles of virology, taxonomy, replication strategies, diagnostic techniques and management of viral diseases is the major attraction of this book.