The study of animal viruses contributes to the general understanding of the molecular basis of viral infection. The emergence of the SARS (Severe Acute Respiratory Syndrome) virus in the human population, coming from an animal source, highlights the importance of animals in harboring infectious agents. In addition, it has been recognized recently that influenza viruses, which persist in their natural avian host, can directly infect humans. In this book, an international panel of leading virologists provide a state-of-the-art overview of the field, comprehensively detailing the current understanding of viruses, their replication, evolution, and interaction with the host. The authors emphasize strategic and methodological aspects of current research, and provide key related references. Topics include foot-and-mouth disease virus, Pestivirus, Arteriviridae, Coronaviruses (including SARS), Herpesviridae, Paramyxoviridae, influenza viruses, Reoviridae, porcine circoviruses, Asfarviridae and much more.