Poxviridae

Poxviridae is a family of large, complex, enveloped double-stranded DNA viruses that infect a broad range of vertebrates and, in some genera, insects. Unlike many DNA viruses, poxviruses replicate entirely in the cytoplasm, using virion-encoded transcription and replication machinery and forming cytoplasmic viral factories.

The family is divided into two subfamilies: Chordopoxvirinae, which infects vertebrates, and Entomopoxvirinae, which infects insects. Genera within Chordopoxvirinae include Orthopoxvirus (variola, vaccinia, cowpox, monkeypox), Parapoxvirus (orf virus, bovine papular stomatitis virus, pseudocowpox virus), Molluscipoxvirus (molluscum contagiosum virus), Avipoxvirus (fowlpox virus, canarypox virus), Capripoxvirus (sheeppox virus, goatpox virus, lumpy skin disease virus), Leporipoxvirus (myxoma virus, rabbit fibroma virus), and Yatapoxvirus (tanapox virus, yaba monkey tumor virus). The Entomopoxvirinae subfamily contains genera that infect insects.

Poxvirus genomes are large linear double-stranded DNA molecules, typically about 130 to 360 kilobases, encoding roughly 150 to 350 genes. Virions are large and brick-shaped, with complex envelopes. In addition to mature virions, poxviruses produce enveloped extracellular virions that disseminate within a host.

Transmission routes vary by virus but commonly include direct contact, respiratory droplets, aerosols, and fomites; some species are vector transmitted in insects. Diseases range from cutaneous and mucosal lesions in humans and animals to systemic illness in livestock and wildlife. Notable human diseases include smallpox (eradicated in 1980) caused by variola virus, and infections by molluscum contagiosum virus.

Eradication efforts and vaccination history, particularly using vaccinia-based vaccines, have shaped the epidemiology of poxvirus infections. Current research focuses on viral evolution, host range, vaccines, and antiviral therapies.