Vaccinia virus | |
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A TEM micrograph of Vaccinia virus virions. | |
Virus classification | |
Group: | Group I (dsDNA) |
Order: | Unassigned |
Family: | Poxviridae |
Subfamily: | Chordopoxvirinae |
Genus: | Orthopoxvirus |
Type species | |
Vaccinia virus |
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Species | |
Vaccinia virus |
Vaccinia | |
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Classification and external resources | |
ICD-10 | B08.0 |
ICD-9-CM | 051.0 |
eMedicine | med/2356 |
MeSH | D014615 |
Vaccinia virus
Vaccinia virus (VACV or VV) is a large, complex, enveloped virus belonging to the poxvirus family. It has a linear, double-stranded DNA genome approximately 190 kbp in length, and which encodes approximately 250 genes. The dimensions of the virion are roughly 360 × 270 × 250 nm, with a mass of approximately 5-10 fg.
Smallpox was the first disease to be widely prevented by vaccination due to pioneering work by the English physician and scientist Edward Jenner in the eighteenth century using cowpox virus. Vaccinia virus is the active constituent of the vaccine that eradicated smallpox, making it the first human disease to be eradicated. This endeavour was carried out by the World Health Organization under the Smallpox Eradication Program. Post eradication of smallpox, scientists study vaccinia virus to use as a tool for delivering genes into biological tissues (gene therapy and genetic engineering) and because of concerns about smallpox being used as an agent for bioterrorism.
In addition to the morbidity of uncomplicated primary vaccination, transfer of infection to other sites by scratching, and post vaccinial encephalitis, other complications of vaccinia infections may be divided into the following types:
Vaccinia virus is closely related to the virus that causes cowpox; historically the two were often considered to be one and the same. The precise origin of vaccinia virus is unknown due to the lack of record-keeping as the virus was repeatedly cultivated and passaged in research laboratories for many decades. The most common notion is that vaccinia virus, cowpox virus, and variola virus (the causative agent of smallpox) were all derived from a common ancestral virus. There is also speculation that vaccinia virus was originally isolated from horses.