Satellite (biology)

Satellite
Scientific classification
(unranked): Subviral agents
(unranked): Satellite
Groups

Satellite viruses
Satellite nucleic acids

A satellite is a subviral agent composed of nucleic acid that depends on the co-infection of a host cell with a helper virus for its replication.

Satellite viruses, which are most commonly associated with plants, but are also found in mammals, arthropods, and bacteria, have the components to make their own protein shell to enclose their genetic material, but rely on a helper virus to replicate. Most viruses have the capability to use host enzymes or their own replication machinery to independently replicate their own viral RNA. Satellite viruses in contrast, are completely dependent on a helper virus for replication. The symbiotic relationship between a satellite and a helper virus to catalyze the replication of a satellite viral genome is also dependent on the host to provide components like replicases[1] to carry out replication.[2] A satellite virus of mamavirus that inhibits the replication of its host has been termed a virophage.[3] However, the usage of this term remains controversial due to the lack of fundamental differences between virophages and classical satellite viruses.[4]

The genomes of satellite viruses range upward from 359 nucleotides in length for satellite tobacco ringspot virus RNA (STobRV).[5]

Satellite viral particles should not be confused with satellite DNA.

Satellite Virus Vs. Virus
Virus Satellite Virus
Replication Able to direct host cell to replicate genome Depends on presence of helper virus for replication of genome
Nucleic acid Contain DNA or RNA or both at different points in life cycle Contain DNA or RNA
Genome Size <10kbp to >2000kbp 0.22-1.5kbp
Structure Contain protein shell or capsid

Packaged genome with a capsid

Envelope-not specific to all viruses

 Satellite viruses contain the protein to encode own capsid with aid of helper virus

Satellite RNA's and DNA's do not have capsids, rely on helper virus to enclose their genome

Host Range Can infect all types of organism; animals, plants, fungi, bacteria, archaea Plants (most common), mammals, arthropods, bacteria

History and Discovery

The tobacco necrosis virus was the virus that lead to the discovery of the first satellite virus in 1962. Scientists discovered that the first satellite had the components to make its own protein shell. A few years later in 1969, scientists discovered another symbiotic relationship with the tobacco ringspot neopvirus (TobRV) and another satellite virus.[6] The emergence of satellite RNA is said to have come from either the genome of the host or its co-infecting agents, and any vectors leading to transmission.[7]

A satellite virus important to human health that demonstrates the need for co-infection to replicate and infect within a host is the virus that causes hepatitis D. Hepatitis D (HDV) was discovered in 1977 by an Mario Rizzetto[8] and is unique from hepatitis A, B, and C because it requires viral particles from hepatitis B to replicate and infect liver cells. Hepatitis B (HBV) provides a surface antigen HBsAg which in return is utilized by HDV to create a super infection resulting in liver failure.[9] Hepatitis delta virus is found all over the globe but most prevalent in Africa, the Middle East and southern Italy.[9]

Classification

  • Satellite viruses- satellites are classified as sub viral agents in that they require the help for co-infection therefore they do not have their own taxonomic classification. There is ongoing talk about proposing new genre for the taxonomic classification of satellites.
  • Satellite nucleic acids
    • Single-stranded satellite DNAs
    • Double-stranded satellite RNAs
      • Saccharomyces cerevisiae M virus satellite
      • Trichomonas vaginalis T1 virus satellite
    • Single-stranded satellite RNAs
      • Subgroup 1: Large satellite RNAs
        • Arabis mosaic virus large satellite RNA
        • Bamboo mosaic virus satellite RNA
        • Chicory yellow mottle virus large satellite RNA
        • Grapevine Bulgarian latent virus satellite RNA
        • Grapevine fanleaf virus satellite RNA
        • Myrobalan latent ringspot virus satellite RNA
        • Tomato black ring virus satellite RNA
        • Beet ringspot virus satellite RNA
      • Subgroup 2: Small linear satellite RNAs
        • Cucumber mosaic virus satellite RNA
        • Cymbidium ringspot virus satellite RNA
        • Pea enation mosaic virus satellite RNA
        • Groundnut rosette virus satellite RNA
        • Panicum mosaic virus small satellite RNA
        • Peanut stunt virus satellite RNA
        • Turnip crinkle virus satellite RNA
        • Tomato bushy stunt virus satellite RNA, B10
        • Tomato bushy stunt virus satellite RNA, B1
      • Subgroup 3: Circular satellite RNAs or "virusoids"
        • Arabis mosaic virus small satellite RNA
        • Cereal yellow dwarf virus-RPV satellite RNA
        • Chicory yellow mottle virus satellite RNA
        • Hepatitis D satellite virus RNA
        • Lucerne transient streak virus satellite RNA
        • Solanum nodiflorum mottle virus satellite RNA
        • Subterranean clover mottle virus satellite RNA
        • Tobacco ringspot virus satellite RNA
        • Velvet tobacco mottle virus satellite RNA

See also

References

  1. ↑ Hu, Chung-Chi; Hsu, Yau-Heiu; Lin, Na-Sheng (2009-12-18). "Satellite RNAs and Satellite Viruses of Plants". Viruses. 1 (3): 1325–1350. doi:10.3390/v1031325.
  2. ↑ Krupovic, Mart; Kuhn, Jens H.; Fischer, Matthias G. (2016-01-01). "A classification system for virophages and satellite viruses". Archives of Virology. 161 (1): 233–247. doi:10.1007/s00705-015-2622-9. ISSN 0304-8608.
  3. ↑ Bernard La Scola; Christelle Desnues; Isabelle Pagnier; Catherine Robert; Lina Barrassi; Ghislain Fournous; Michèle Merchat; Marie Suzan-Monti; Patrick Forterre; Eugene Koonin & Didier Raoult (2008). "The virophage as a unique parasite of the giant mimivirus". Nature. 455 (7205): 100–4. doi:10.1038/nature07218. PMID 18690211.
  4. ↑ Krupovic M; Cvirkaite-Krupovic V (2011). "Virophages or satellite viruses?". Nat Rev Microbiol. 9 (11): 762–763. doi:10.1038/nrmicro2676. PMID 22016897.
  5. ↑ Wayne L. Gerlach; Jamal M. Buzayan; Irving R. Schneider; George Bruening (1986). "Satellite Tobacco Ringspot Virus RNA: Biological Activity of DNA Clones and Their in Vitro Transcripts". Virology. 151: 172–185. doi:10.1016/0042-6822(86)90040-1.
  6. ↑ Roossinck, M. J.; Sleat, D.; Palukaitis, P. (June 1992). "Satellite RNAs of plant viruses: structures and biological effects". Microbiological Reviews. 56 (2): 265–279. ISSN 0146-0749. PMC 372867. PMID 1620065.
  7. ↑ Hu, Chung-Chi; Hsu, Yau-Heiu; Lin, Na-Sheng (2009). "Satellite RNAs and Satellite Viruses of Plants". Viruses. 1 (3): 1325–1350. doi:10.3390/v1031325.
  8. ↑ "Hepatitis D Virus". web.stanford.edu. Retrieved 2017-12-01.
  9. 1 2 "Hepatitis D: Background, Etiology, Epidemiology". 2017-11-20.
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