The Orthopoxviruses presents knowledge and comprehensive and integrated picture of orthopoxviruses. The book looks into the molecular biology of this genusof viruses, particularly, the structure and chemical composition of the virion, replication, morphogenesis, pathogenesis, pathology, and immunology of this virus’ infections. It also elucidates the global spread, control, and eradication of smallpox. Additionally, the book describes a potentially important use of vaccinia virus, namely, its use as a vector for genes from other viruses, bacteria, or protozoa that specify antigens important in stimulating the production of a protective immune response. Such comprehensive account of all aspects of the biology of all known species of orthopoxviruses will be valuable to molecular biologists, virologists, immunologists, pathologists, and researchers in the veterinary sciences.