Providing an integrated account of the subject across different host systems, with an emphasis on human and animal viruses, this book covers the field of virology from molecular biology to disease processes using a systems approach. Featuring full color illustrations, the new edition has been updated throughout, and reorganized into thematic sections on the fundamental nature of viruses, their growth in cells, their interactions with the host organism, and their role as agents of human disease. There is a new chapter on human viral disease, and rapidly developing areas, such as the use of viruses as gene therapy vectors, have been included.