General Description

Characteristics of the Virion

The variola virion has one of the longest genomes of any virus, with 187,000 nucleotides and 200 genes. The complexity of the virus is apparent in comparing it to the AIDS virus, which only has ten genes. The smallpox virus contains 200 distinct proteins. (15:32) (15:33)

The virion is approximately 0.2 - 0.3 microns (19:4) with a brick-shaped exterior structure that has a diameter of about 200nm and a crinkly, knobby surface that some experts call the mulberry of pox. (15:32) At the center of the virion is a dumbbell-shaped core which contains the double-stranded DNA genome.

Poxviruses are unique among DNA viruses in that they replicate in the cytoplasm of the cell rather than in the nucleus (19:4) This is facilitated by a variety of viral proteins produced in the host cell cytoplasm.

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