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Negative-sense single-stranded RNA virus

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Negative ssRNA Virus
Ebola Virus
Virus classification
Group:
Group V ((−)ssRNA)
Order, Family, and Genus


Negative-Sense Single Strand RNA Viruses

A negative-sense single strand RNA virus (or (-)ssRNA virus) is a virus that uses negative sense RNA as its genetic material. Single stranded RNA viruses are classified as positive or negative depending on the sense or polarity of the RNA. The negative viral RNA is complementary to the mRNA and must be converted to a positive RNA by RNA polymerase before transcription. Therefore, the purified RNA of a negative sense virus is not infectious by itself, as it needs to be converted to a positive sense RNA for replication. The virus belongs to Group V on the Baltimore classification.[1]


Replication

Negative sense ssRNA virus needs RNA polymerase to form a positive sense RNA. The positive sense RNA acts as a viral mRNA, which is translated into proteins for the production of new virion materials. With the newly formed virions, more negative sense RNA molecules are produced.

In more details, replication of the virus consists of the following steps:[2][3][4]

  1. A virion enters the host cell and releases its negative RNA into the cytoplasm.
  2. The virus uses its own RNA replicase, also known as RNA-dependent RNA polymerase (RdRp), to form positive RNA template strands through complementary base pairing.
  3. The positive RNA acts as mRNA, which is translated into structural capsomere proteins and viral RdRp by the host's ribosomes.
  4. A replicative complex is formed with RdRp: The positive strands can either function as mRNA to produce more proteins or as template to make more negative RNA strands.
  5. New viral capsids are assembled with the capsomere proteins. The negative RNA strands combine with capsids and viral RdRp to form new negative RNA virions.
  6. After assembly and maturation of nucleocapsid, the new virions exit the cell by budding or lysing through cell membrane to further infect other cells.

The genome size of a negative RNA virus is between 10kb to 30kb. Two genome subgroups can be distinguished, nonsegmented and segmented, and are described as such:

  • In viruses with nonsegmented genomes, the first step of replication is transcription of the negative strand by RdRp to form various monocistronic mRNA that code for individual viral proteins. A positive strand copy is formed to serve as template for the production of the negative genome. This replication takes place in the cytoplasm.
  • In viruses with segmented genomes, replication occurs in the nucleus and the RdRp produces one monocistronic mRNA strand from each genome segment. The principal difference between the two types is the location of replication.

Taxonomy

One order and eight families are currently recognised in this group. Four of these families contain extremely similar genetic structures and are classified under the order Mononegavirales.[5] A number of unassigned species and genera are yet to be classified.[6]

Host range

Viruses of the families Arenaviridae, Orthomyxoviridae, and Paramyxoviridae are able to infect vertebrates. Viruses of the families Bunyaviridae and Rhabdoviridae are able to infect vertebrates, arthropods, and plants. Viruses of the family Tenuivirus only infect plants. A few viruses known to infect humans include Marburg virus, Ebola, measles, mumps, rabies, and influenza.

See also

References

  1. ^ "ICTVdb Index of Viruses: Virus Taxonomy, 8th Reports of the International Committee on Taxonomy of Viruses: Listing in Taxonomic Order." (Website). U.S. National Center for Biotechnology Information, National Library for Medicine, National Institutes of Health. Accessed 28 September 2007.
  2. ^ Charles E. Samuel (2005) Virus-Host Interaction Minireview Series: Human Immunodeficiency Virus, Hepatitis C Virus, and Influenza Virus, J. Biol. Chem., Vol. 281, Issue 13, 8305-8307. doi: 10.1074
  3. ^ Hofkin, Bruce (2010). Living in a Microbial World. Garland Science. ISBN 9780815341758.
  4. ^ Rybicki, Ed. "Viral Replication Strategy in Negative-Sense Single-Stranded RNA Viruses". ASM Microbe Library. American Society for Microbiology. Retrieved 14 April 2015.
  5. ^ Cann, Alan (2011). Principles of Molecular Virology. Academic Press. ISBN 978-0-12-384939-7.
  6. ^ Klein, Donald W.; Prescott, Lansing M.; Harley, John (1993). Microbiology. Dubuque, Iowa: Wm. C. Brown. ISBN 0-697-01372-3.{{cite book}}: CS1 maint: multiple names: authors list (link)
  7. ^ Mihindukulasuriya, K. A.; Nguyen, N. L.; Wu, G.; Huang, H. V.; Travassos da Rosa, A. P.; Popov, V. L.; Tesh, R. B.; Wang, D. (2009). "Nyamanini and Midway viruses define a novel taxon of RNA viruses in the order Mononegavirales". J. Virol. 83 (10): 5109–16. doi:10.1128/JVI.02667-08. PMC 2682064. PMID 19279111.
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