Sudan ebolavirus explained

The species Sudan ebolavirus is a virological taxon included in the genus Ebolavirus, family Filoviridae, order Mononegavirales. The species has a single virus member, Sudan virus (SUDV). The members of the species are called Sudan ebolaviruses. It was discovered in 1977 and causes Ebola clinically indistinguishable from the ebola Zaire strain, but is less transmissible than it. Unlike with ebola Zaire there is no vaccine available.

Nomenclature

The name Sudan ebolavirus is derived from Sudan (the country in which Sudan virus was first discovered) and the taxonomic suffix ebolavirus (which denotes an ebolavirus species).

The species was introduced in 1998 as Sudan Ebola virus.[1] [2] In 2002, the name was changed to Sudan ebolavirus.[3]

A virus of the genus Ebolavirus is a member of the species Sudan ebolavirus if:

Sudan virus (SUDV) is one of six known viruses within the genus Ebolavirus and one of the four that causes Ebola virus disease (EVD) in humans and other primates; it is the sole member of the species Sudan ebolavirus. SUDV is a Select agent, World Health Organization Risk Group 4 Pathogen (requiring Biosafety Level 4-equivalent containment), National Institutes of Health/National Institute of Allergy and Infectious Diseases Category A Priority Pathogen, Centers for Disease Control and Prevention Category A Bioterrorism Agent, and listed as a Biological Agent for Export Control by the Australia Group.

The first known outbreak of EVD occurred due to Sudan virus in South Sudan between June and November 1976, infecting 284 people and killing 151, with the first identifiable case on 27 June 1976.[4] [5] [6]

Use of term

Sudan virus (abbreviated SUDV) was first described in 1977.[7] It is the single member of the species Sudan ebolavirus, which is included into the genus Ebolavirus, family Filoviridae, order Mononegavirales.[8] The name Sudan virus is derived from South Sudan (where it was first discovered before South Sudan seceded from Sudan[9]) and the taxonomic suffix virus.

Previous designations

Sudan virus was first introduced as a new "strain" of Ebola virus in 1977.[7] Sudan virus was described as "Ebola haemorrhagic fever" in a 1978 WHO report describing the 1976 Sudan outbreak.[10] In 2000, it received the designation Sudan Ebola virus[11] [12] and in 2002 the name was changed to Sudan ebolavirus.[13] [3] Previous abbreviations for the virus were EBOV-S (for Ebola virus Sudan) and most recently SEBOV (for Sudan Ebola virus or Sudan ebolavirus). The virus received its final designation in 2010, when it was renamed Sudan virus (SUDV).[8]

Virus inclusion criteria

A virus of the species Sudan ebolavirus is a Sudan virus (SUDV) if it has the properties of Sudan ebolaviruses and if its genome diverges from that of the prototype Sudan virus, Sudan virus variant Boniface (SUDV/Bon), by ≤10% at the nucleotide level.[8]

Disease

See main article: articles and Ebola. SUDV is one of four ebolaviruses that causes Ebola virus disease (EVD) in humans (in the literature also often referred to as Ebola hemorrhagic fever, EHF). EVD due to SUDV infection cannot be differentiated from EVD caused by other ebolaviruses by clinical observation alone, which is why the clinical presentation and pathology of infections by all ebolaviruses is presented together on a separate page. The strain is less transmissible than Zaire ebolavirus.[14]

In the past, SUDV has caused the following EVD outbreaks:[15] [16]

Ebola virus disease (EVD) outbreaks due to Sudan virus (SUDV) infection
YearGeographic locationHuman cases/deaths (case-fatality rate)
1976Juba, Maridi, Nzara, and Tembura, South Sudan284/151 (53%)
1979Nzara, South Sudan34/22 (65%)
2000–2001Gulu, Mbarara, and Masindi Districts, Uganda425/224 (53%)
2004Yambio County, South Sudan17/7 (41%)
2011Luweero District, Uganda1/1 (100%)
2014Equateur, Congo[17] 0/1 * two strains reported, one Sudan and one Sudan/Zaire Hybrid to 24/08/2014 (0%)
2022-2023Central and Western Regions, Uganda164/77 (47%)

Vaccine development

As of 2022, there are six experimental vaccines but only three have advanced to the stage where human clinical trials have begun.[18]

As the Public Health Agency of Canada developed a candidate RVSV vaccine for Sudan ebolavirus. Merck was developing it, but had discontinued development; Merck's monopolies on rVSV techniques, acquired with funding from GAVI, are not available to others developing rVSV vaccines.[19]

As of 2021 GeoVax was developing MVA-SUDV-VLP, which is a modified vaccinia Ankara virus producing Sudan virus-like particles; early data from their research showed the GeoVax vaccine candidate to be 100% effective at preventing death from the Sudan ebolavirus in animals.[20]

An adenovirus based vaccine previously licensed by GSK was donated to and further developed by the Sabin Vaccine Institute in partnership with the Vaccine Research Center at the US National Institute of Allergy and Infectious Diseases; as of October 2022, it will be offered to contacts of known SDV cases in the 2022 Uganda Ebola outbreak as part of a clinical trial.[18]

Ecology

The ecology of SUDV is currently unclear and no reservoir host has yet been identified. Therefore, it remains unclear how SUDV was repeatedly introduced into human populations. As of 2009, bats have been suspected to harbor the virus because infectious Marburg virus (MARV), a distantly related filovirus, has been isolated from bats,[21] and because traces (but no infectious particles) of the more closely related Ebola virus (EBOV) were found in bats as well.[22]

Molecular biology

SUDV is basically uncharacterized on a molecular level. However, its genomic sequence, and with it the genomic organization and the conservation of individual open reading frames, is similar to that of the other four known ebolaviruses. It is therefore currently assumed that the knowledge obtained for EBOV can be extrapolated to SUDV and that all SUDV proteins behave analogous to those of EBOV.

External links

Notes and References

  1. Book: Netesov. S. V.. Feldmann. H.. Jahrling. P. B.. Klenk. H. D.. Sanchez. A.. Family Filoviridae. 2000. van Regenmortel. M. H. V.. Fauquet. C. M.. Bishop. D. H. L.. Carstens. E. B.. Estes. M. K.. Lemon. S. M.. Maniloff. J.. Mayo. M. A.. McGeoch. D. J.. Pringle. C. R.. Wickner. R. B.. Virus Taxonomy—Seventh Report of the International Committee on Taxonomy of Viruses. 539–48. Academic Press. San Diego, USA. 978-0-12-370200-5.
  2. Pringle. C. R.. 1998. Virus taxonomy-San Diego 1998. Archives of Virology. 143. 7. 1449–59. 9742051. 10.1007/s007050050389. 13229117.
  3. Mayo. M. A.. 2002. ICTV at the Paris ICV: results of the plenary session and the binomial ballot. Archives of Virology. 147. 11. 2254–60. 10.1007/s007050200052. 43887711. free.
  4. Web site: Ebola haemorrhagic fever in Sudan, 1976. dead. https://web.archive.org/web/20141013194802/http://whqlibdoc.who.int/bulletin/1978/Vol56-No2/bulletin_1978_56(2)_247-270.pdf. 13 October 2014. dmy-all.
  5. 10.1016/S0140-6736(10)60667-8 . 21084112 . Feldmann . H. . Geisbert . T. W. . Ebola haemorrhagic fever . The Lancet . 377 . 9768 . 849–862 . 2011 . 3406178.
  6. Hoenen T, Groseth A, Feldmann H . Current ebola vaccines. Expert Opin Biol Ther. 12. 7. 859–72. July 2012. 22559078. 3422127. 10.1517/14712598.2012.685152.
  7. Bowen. E. T. W.. Lloyd. G.. Harris. W. J.. Platt. G. S.. Baskerville. A.. Vella. E. E.. 1977. Viral haemorrhagic fever in southern Sudan and northern Zaire, Preliminary studies on the aetiological agent.. Lancet. 309. 8011. 571–3. 65662. 10.1016/s0140-6736(77)92001-3. 3092094.
  8. Kuhn. Jens H.. Becker. Stephan. Ebihara. Hideki. Geisbert. Thomas W.. Johnson. Karl M.. Kawaoka. Yoshihiro. Lipkin. W. Ian. Negredo. Ana I. Netesov. Sergey V.. Nichol. Stuart T.. Palacios. Gustavo. Peters. Clarence J.. Tenorio. Antonio. Volchkov. Viktor E.. Jahrling. Peter B.. 2010. Proposal for a revised taxonomy of the family Filoviridae: Classification, names of taxa and viruses, and virus abbreviations. Archives of Virology. 155. 12. 2083–103. 10.1007/s00705-010-0814-x. 21046175. 3074192. 8.
  9. https://books.google.com/books?id=BbjFAAAAQBAJ&dq=Nzara%2C+South+Sudan&pg=PA61 Nzara, South Sudan
  10. Web site: Home . 2015-02-11 . dead . https://web.archive.org/web/20141013194802/http://whqlibdoc.who.int/bulletin/1978/Vol56-No2/bulletin_1978_56(2)_247-270.pdf . 13 October 2014 . dmy-all .
  11. Book: Netesov. S. V.. Feldmann. H.. Jahrling. P. B.. Klenk. H. D.. Sanchez. A.. Family Filoviridae. 2000. van Regenmortel. M. H. V.. Fauquet. C. M.. Bishop. D. H. L.. Carstens. E. B.. Estes. M. K.. Lemon. S. M.. Maniloff. J.. Mayo. M. A.. McGeoch. D. J.. Pringle. C. R.. Wickner. R. B.. Virus Taxonomy – Seventh Report of the International Committee on Taxonomy of Viruses. 539–48. Academic Press. San Diego, USA. 978-0-12-370200-5.
  12. Pringle. C. R.. 1998. Virus taxonomy-San Diego 1998. Archives of Virology. 143. 7. 1449–59. 9742051. 10.1007/s007050050389. 13229117.
  13. Book: Feldmann. H.. Geisbert. T. W.. Jahrling. P. B.. Klenk. H.-D.. Netesov. S. V.. Peters. C. J.. Sanchez. A.. Swanepoel. R.. Volchkov. V. E.. Family Filoviridae. 2005. Fauquet. C. M.. Mayo. M. A.. Maniloff. J.. Desselberger. U.. Ball. L. A.. Virus Taxonomy – Eighth Report of the International Committee on Taxonomy of Viruses. 645–653. Elsevier/Academic Press. San Diego, USA. 978-0-12-370200-5.
  14. News: Biryabarema . Elias . 2022-09-22 . Uganda has confirmed seven Ebola cases so far, one death . en . Reuters . 2022-09-23.
  15. News: 2014-08-24 . Ebola outbreak: DR Congo confirms two deaths . BBC .
  16. Web site: Ebola Disease caused by Sudan virus – Uganda . 27 September 2022 . www.who.int . en.
  17. News: Ebola outbreak: DR Congo confirms two deaths. BBC. 2014-08-24.
  18. Web site: Helen Branswell . 2022-09-29 . Ebola experimental vaccine trial may begin soon in Uganda . 2022-10-10 . STAT News . en-US.
  19. Web site: 2018-09-25 . MSF's response to CEPI's policy regarding equitable access . 2022-09-23 . Médecins Sans Frontières Access Campaign . en . In vaccine development, access to know how is important. Knowledge and expertise including but not limited to purification techniques, cell lines, materials, software codes and their transfer of this to alternative manufacturers in the event the awardee discontinues development of a promising vaccine is critically important. The recent example of Merck abandoning the development of rVSV vaccines for Marburg (rVSV-MARV) and for Sudan-Ebola (rVSV-SUDV) is a case in point. Merck continues to retain vital know-how on the rVSV platform as it developed the rVSV vaccine for Zaire-Ebola (rVSV-ZEBOV) with funding support from GAVI. While it has transferred the rights on these vaccines back to Public Health Agency of Canada, there is no mechanism to share know how on the rVSV platform with other vaccine developers who would like to also use rVSV as a vector against other pathogens..
  20. Web site: 2021-07-21 . GeoVax Announces Presentation of Sudan Ebolavirus Vaccine Data at the American Society for Virology Annual Meeting .
  21. Towner . J. S. . Amman . B. R. . Sealy . T. K. . Carroll . S. A. R. . Comer . J. A. . Kemp . A. . Swanepoel . R. . Paddock . C. D. . Balinandi . S. . Khristova . M. L. . Formenty . P. B. . Albarino . C. G. . Miller . D. M. . Reed . Z. D. . Kayiwa . J. T. . Mills . J. N. . Cannon . D. L. . Greer . P. W. . Byaruhanga . E. . Farnon . E. C. . Atimnedi . P. . Okware . S. . Katongole-Mbidde . E. . Downing . R. . Tappero . J. W. . Zaki . S. R. . Ksiazek . T. G. . Nichol . S. T. . Rollin . P. E. . Fouchier . Ron A. M. . Isolation of Genetically Diverse Marburg Viruses from Egyptian Fruit Bats . 10.1371/journal.ppat.1000536 . PLOS Pathogens . 5 . 7 . e1000536 . 2713404 . 2009 . 19649327. free .
  22. Fruit bats as reservoirs of Ebola virus. Nature. 438. 7068. 575–576. 2005. 16319873 . R.. 10.1038/438575a. 2005Natur.438..575L. Leroy . E. M.. Kumulungui . B.. Swanepoel. Pourrut . X.. Rouquet . P.. Hassanin . A.. Yaba . P.. Délicat . A.. Paweska . J. T.. Gonzalez . J. P. . 4403209.

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