Class I viruses with a double-stranded DNA genome that encodes more than 30 polypeptides. They are the largest viruses and have a complex multilayered coat composed of lipid and enzymes, including a DNA-dependent RNA polymerase. They multiply in the cytoplasm of the cell. Four genera cause human infections: orthopox, parapox, yatapox, and molluscipox. Important examples are vaccinia, variola (smallpox), and myxoma.
Subjects: Medicine and Health.