Definition of Orthopox
Orthopox: The family of viruses to which belongs vaccinia, the virus that causes smallpox.
Other members of the orthopox family of viruses capable of infecting humans include:
Poxviruses are very large rectangular viruses the size of small bacteria. They have a complex internal structure with a large double-stranded DNA genome enclosed within a "core" that is flanked by 2 "lateral bodies". The surface of the virus particle is covered with filamentous protein components, so that the particles have the appearance of a "ball of knitting wool". The entire particle is enclosed in an envelope derived from the host cell membranes. Most poxviruses are host-species specific, but vaccinia is a remarkable exception. True pox viruses are antigenically rather similar, so that infection by one elicits immune protection against the others.
Last Editorial Review: 6/14/2012
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