Poxviruses

Abstract

The Poxviridae family comprises large, complex DNA viruses that infect a wide variety of vertebrate and invertebrate hosts (chordopoxviruses and entomopox-viruses, respectively). Within the chordopoxvirus subfamily, the orthopoxvirus genus is best known for containing variola (VARV), the etiological agent of smallpox, and vaccinia (VACV), the virus used as the vaccine in the successful campaign to eradicate smallpox. Vaccinia has also served as the prototype for experimental investigation of poxvirus biology, and the following review will focus on vaccinia replication. Despite possessing DNA genomes, these viruses replicate exclusively in the cytoplasm of the infected host cell. This unusual physical autonomy from the host nucleus is accompanied by genetic autonomy; the ∼200 viral gene products encode a repertoire of proteins that mediate three temporally regulated phases of gene expression, genome replication, and virion morphogenesis. Poxviruses also encode a plethora of proteins that intersect with, and modulate, many cellular signaling cascades and components of the innate immune response.