Vanya Choumanova
Winter, 2004
Humans and Viruses
Robert Siegel


Poxviridae are morphologically the largest viruses. They are brick-shaped or ovoid viruses, and their structure is referred to as complex: their capsids are neither icosahedral nor helical. Their genome is dsDNA and codes for more than 100 polypeptides, including a DNA-dependent RNA polymerase. Unlike most DNA viruses, poxviruses replicate in the cytoplasm and can replicate in cells lacing nuclei.

Poxviridae contains two subfamilies: the Chordopoxvirinae, which has eight genera and infects a wide range of mammals and birds, and the Entomopoxvirinae with three genera that affect only insects. The following poxviruses affect humans:
Bovine papular stomatitis
Molluscum contagiosum
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Smallpox, caused by variola virus, has led to at least three "firsts:" the first vaccine, the first disease to be eradicated by immunization, and the first virus infection against which chemotherapy was clinically effective. In the past few years, many other "firsts" have taken place in this viral family: monkeypox emerged in the Western Hemisphere and the first case of inadvertent contact vaccinia transmission from a breasfeeding mother to infant was reported. Smallpox, although eradicated, infiltrated our homes, as politicians discussed the potential for a bioterror attack and whether to vaccinate or not to vaccinate the people of the United States.

Poxviridae is a "complex" family of viruses: morphologically, politically, economically, and socially. So go ahead, explore and learn a lot more about Poxviridae!