Smallpox causes
|
Smallpox Microchapters |
|
Diagnosis |
|---|
|
Treatment |
|
Case Studies |
|
Smallpox causes On the Web |
|
American Roentgen Ray Society Images of Smallpox causes |
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:[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, 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, yet they differ clinically. This leads to the assumption that the difference in virulence resides in alternate gene expression.[1][6]
Poxviruses survive in cold and dry environments being able to survive in the aerosol form, and are killed by hospital disinfectants and UV light.[1][6][7][8]
Unlike other DNA viruses, poxviruses replicate within the cytoplasm of the host cell. In order to replicate, poxviruses produce a variety of specialized proteins not produced by other DNA viruses, the most important of which is a viral-associated DNA-dependent RNA polymerase.
Origin
Tropism
Natural reservoir
Humans are the only natural reservoir of smallpox virus.[9]
References
- ↑ 1.0 1.1 1.2 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.
- ↑ 6.0 6.1 "Smallpox and its Eradication" (PDF).
- ↑ Thomas G (1974). "Air sampling of smallpox virus". J Hyg (Lond). 73 (1): 1–7. PMC 2130554. PMID 4371586.
- ↑ HARPER GJ (1961). "Airborne micro-organisms: survival tests with four viruses". J Hyg (Lond). 59: 479–86. PMC 2134455. PMID 13904777.
- ↑ "Smallpox disease overview".