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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]
Overview
Smallpox is caused by the variola virus.
Taxonomy
Viruses; dsDNA; Poxviridae; Chordopoxvirinae; Orthopoxvirus; Variola vera
Biology
Variola virus is a orthopoxvirus, from the family Poxviridae, the largest viruses to infect humans. It is a 200-400 nm dsDNA virus, lacking icosahedral symmetry. The other viruses of the family Poxviridae include the vaccinia, the molluscum contagiosum, the cowpox and the monkeypox.[1] The viral structure includes:[2][3][4]
- Outer membrane
- 2 lateral bodies
- 1 dsDNA molecule in its core containing 186,999 base pairs
Variola virus genes are similar to the ones of vaccinia virus. Since there is cross-protection between poxviruses within a same genus, it was possible to use the second as a vaccine for smallpox virus.[5]
There are 2 forms of variola virus:
- Variola major
- Variola minor
Both strains of the virus share a large amount of genome, which leads to the assumption that the difference in virulence resides in alternate gene expression.
Origin
Tropism
Natural reservoir
Humans are the only natural reservoir of smallpox virus.[6]
References
- ↑ Moore, Zack S; Seward, Jane F; Lane, J Michael (2006). "Smallpox". The Lancet. 367 (9508): 425–435. doi:10.1016/S0140-6736(06)68143-9. ISSN 0140-6736.
- ↑ Fields, Bernard (2007). Fields virology. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. ISBN 0781760607.
- ↑ Massung RF, Liu LI, Qi J, Knight JC, Yuran TE, Kerlavage AR; et al. (1994). "Analysis of the complete genome of smallpox variola major virus strain Bangladesh-1975". Virology. 201 (2): 215–40. doi:10.1006/viro.1994.1288. PMID 8184534.
- ↑ Massung RF, Loparev VN, Knight JC, Totmenin AV, Chizhikov VE, Parsons JM; et al. (1996). "Terminal region sequence variations in variola virus DNA". Virology. 221 (2): 291–300. doi:10.1006/viro.1996.0378. PMID 8661439.
- ↑ Shchelkunov, Sergei N.; Resenchuk, Sergei M.; Totmenin, Alexei V.; Blinov, Vladimir M.; Marennikova, Svetlana S.; Sandakhchiev, Lev S. (1993). "Comparison of the genetic maps of variola and vaccinia viruses". FEBS Letters. 327 (3): 321–324. doi:10.1016/0014-5793(93)81013-P. ISSN 0014-5793.
- ↑ "Smallpox disease overview".