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Reoviridae

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Reoviridae

Reoviridae is a family of viruses. They have a wide host range, including vertebrates, invertebrates, plants, and fungi.[1] There are currently 87 species in this family, divided among 30 genera.[2] Reoviruses can affect the gastrointestinal system (such as Rotavirus) and respiratory tract.[3] The name "Reo-" is derived from respiratory enteric orphan viruses.[4] The term "orphan virus" refers to the fact that some of these viruses have been observed not associated with any known disease. Even though viruses in the Reoviridae family have more recently been identified with various diseases, the original name is still used.

Reovirus infection occurs often in humans, but most cases are mild or subclinical. Rotavirus, however, can cause severe diarrhea and intestinal distress in children. The virus can be readily detected in feces, and may also be recovered from pharyngeal or nasal secretions, urine, cerebrospinal fluid, and blood. Despite the ease of finding Reovirus in clinical specimens, their role in human disease or treatment is still uncertain.

Some viruses of this family infect plants. For example, Phytoreovirus and Oryzavirus.

Contents

  • Structure 1
  • Life Cycle 2
  • Multiplicity reactivation 3
  • Taxonomy 4
    • Other Reoviridae 4.1
  • Therapeutic applications 5
  • See also 6
  • References 7
  • External links 8

Structure

Reoviruses are non-enveloped and have an icosahedral capsid composed of an outer (T=13) and inner (T=2) protein shell.[1][4] The genomes of viruses in Reoviridae contain 10–12 segments which are grouped into three categories corresponding to their size: L (large), M (medium) and S (small). Segments range from about 3.9 to 1 kbp and each segment encodes 1–3 proteins (10-14 proteins in total[1]). Reoviridae proteins are denoted by the Greek character corresponding to the segment it was translated from (the L segment encodes for λ proteins, the M segment encodes for μ proteins and the S segment encodes for σ proteins).[4]

Genus Structure Symmetry Capsid Genomic Arrangement Genomic Segmentation
Aquareovirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented
Rotavirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented
Seadornavirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented
Coltivirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented
Fijivirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented
Phytoreovirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented
Mimoreovirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented
Orbivirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented
Cypovirus Icosahedral T=2 Non-Enveloped Linear Segmented
Orthoreovirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented
Idnoreovirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented
Dinovernavirus Icosahedral T=2 Non-Enveloped Linear Segmented
Oryzavirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented
Cardoreovirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented
Mycoreovirus Icosahedral T=13, T=2 Non-Enveloped Linear Segmented

Life Cycle

Viruses in the family Reoviridae have genomes consisting of segmented, double-stranded RNA (dsRNA).[3] Because of this, replication occurs exclusively in the cytoplasm and the virus encodes several proteins which are needed for replication and conversion of the dsRNA genome into (+)-RNAs. The virus can enter the host cell via a receptor on the cell surface. The receptor is not known but is thought to include sialic acid and junctional adhesion molecules (JAMs).[5] The virus is partially uncoated by proteases in the endolysosome, where the capsid is partially digested to allow further cell entry. The core particle then enters the cytoplasm by a yet unknown process where the genome is transcribed conservatively causing an excess of (+) sense strands, which are used as mRNA templates to synthesize (−) sense strands. Viral particles begin to assemble in the cytoplasm 6–7 hours after infection.

Translation takes place by leaky scanning, suppression of termination, and ribosomal skipping. The virus exits the host cell by monopartite non-tubule guided viral movement, cell to cell movement, and existing in occlusion bodies after cell death and remaining infectious until finding another host.[1]

Genus Host Details Tissue Tropism Entry Details Release Details Replication Site Assembly Site Transmission
Aquareovirus Aquatic vertebrates: fish; aquatic invertebrates: shellfish; aquatic invertebrates: crustaceans None Cell receptor endocytosis Cell death Cytoplasm Cytoplasm Passive diffusion
Rotavirus Humans; vertebrates Intestinal mucosa Clathrin-mediated endocytosis Cell death Cytoplasm Cytoplasm Oral-fecal
Seadornavirus Humans; cattle; pigs; mosquitoes None Cell receptor endocytosis Cell death Cytoplasm Cytoplasm Zoonosis; arthropod bite
Coltivirus Humans; rodents; ticks; mosquitoes Erythrocytes Cell receptor endocytosis Cell death Cytoplasm Cytoplasm Arthropod bite
Fijivirus Plants: gramineae; plants: liliacea; planthoppers Phloem Viral movement; mechanical inoculation Cell death Cytoplasm Cytoplasm Delphacid plant hoppers
Phytoreovirus Oryza sativa; leafhoppers Phloem Viral movement; mechanical inoculation Cell death Cytoplasm Cytoplasm Leafhoppers
Mimoreovirus Algae None Cell receptor endocytosis Cell death Cytoplasm Cytoplasm Arthropod bite
Orbivirus Vertebrates; mosquitoes; midges; gnats; sandflies; ticks None Cell receptor endocytosis Cell death Cytoplasm Cytoplasm Arthropod bite
Cypovirus Insects Midgut; goblet; fat Cell receptor endocytosis Cell death Cytoplasm Cytoplasm Polyhedra: oral-fecal; vertical: eggs
Orthoreovirus Vertebrates Epithelium: intestinal; epithelium:bile duct; epithelium: lung; leukocytes; endothelium: CNS Clathrin-mediated endocytosis Cell death Cytoplasm Cytoplasm Aerosol; oral-fecal
Idnoreovirus Hymenoptera Gut Cell receptor endocytosis Cell death Cytoplasm Cytoplasm Unknown
Dinovernavirus Insects; Mosquitoes None Unknown Cell death Cytoplasm Cytoplasm Unknown
Oryzavirus Plants: graminae, Oryza sativa; planthoppers None Viral movement; mechanical inoculation Cell death Cytoplasm Cytoplasm Delphacid planthoppers
Cardoreovirus Crustaceans: crabs None Cell receptor endocytosis Cell death Cytoplasm Cytoplasm Arthropod bite
Mycoreovirus Fungi Mycelium Cell death; cytoplasmic exchange, sporogenesis; hyphal anastomosis Cell death; cytoplasmic exchange, sporogenesis; hyphal anastomosis Cytoplasm Cytoplasm Cytoplasmic exchange, sporogenesis; hyphal anastomosis

Multiplicity reactivation

Multiplicity reactivation (MR) is the process by which 2 or more virus genomes, each containing inactivating genome damage, can interact within an infected cell to form a viable virus genome. McClain and Spendlove[6] demonstrated MR for three types of reovirus after exposure to ultraviolet irradiation. In their experiments, reovirus particles were exposed to doses of UV-light that would be lethal in single infections. However, when two or more inactivated viruses were allowed to infect individual host cells MR occurred and viable progeny were produced. As they stated, multiplicity reactivation by definition involves some type of repair. Michod et al.[7] reviewed numerous examples of MR in different viruses, and suggested that MR is a common form of sexual interaction in viruses that provides the benefit of recombinational repair of genome damages.

Taxonomy

Group: dsRNA

[2]

The Reoviridae are divided into two subfamilies[8] based on the presence of a "turret" protein on the inner capsid.[9][10] From ICTV communications: "The name Spinareovirinae will be used to identify the subfamily containing the spiked or turreted viruses and is derived from ‘reovirus’ and the Latin word ‘spina’ as a prefix, which means spike, denoting the presence of spikes or turrets on the surface of the core particles. The term ‘spiked’ is an alternative to ‘turreted’, that was used in early research to describe the structure of the particle, particularly with the cypoviruses. The name Sedoreovirinae will be used to identify the subfamily containing the non-turreted virus genera and is derived from ‘reovirus’ and the Latin word ‘sedo’, which means smooth, denoting the absence of spikes or turrets from the core particles of these viruses, which have a relatively smooth morphology."[11]

Phylogenetic comparison of the viral polymerase protein sequences of viruses of the family Reoviridae. Arrow indicates a common phylogenetic origin between seadornaviruses and rotaviruses.

Other Reoviridae

Additionally, there is one proposed genus that has not yet been accepted by the ICTV:

Piscine reovirus is a Spinareovirinae-like virus that has not yet been classified.[13]

Therapeutic applications

The reoviruses have been demonstrated to have oncolytic (cancer-killing) properties, encouraging the development of reovirus-based therapies for cancer treatment.[14][15]

Reolysin is a formulation of reovirus that is currently in clinical trials for the treatment of various cancers.[16]

See also

References

  1. ^ a b c d "Viral Zone". ExPASy. Retrieved 15 June 2015. 
  2. ^ a b ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015. 
  3. ^ a b Patton JT (editor). (2008). Segmented Double-stranded RNA Viruses: Structure and Molecular Biology. Caister Academic Press. isbn = 978-1-904455-21-9. 
  4. ^ a b c MicrobiologyBytes—Reoviruses
  5. ^ Barton, ES; Forrest, JC; Connolly, JL; Chappell, JD; Liu, Y; Schnell, FJ; Nusrat, A; Parkos, CA; Dermody, TS (Feb 9, 2001). "Junction adhesion molecule is a receptor for reovirus.". Cell 104 (3): 441–51.  
  6. ^ McClain ME, Spendlove RS (November 1966). "Multiplicity reactivation of reovirus particles after exposure to ultraviolet light". J. Bacteriol. 92 (5): 1422–9.  
  7. ^ Michod, R. E.; Bernstein, H.; Nedelcu, A. M. (2008). "Adaptive value of sex in microbial pathogens". Infection, Genetics and Evolution 8 (3): 267–285.  
  8. ^ Carstens, E. B. (January 2010). "Ratification vote on taxonomic proposals to the International Committee on Taxonomy of Viruses (2009)" (PDF). Archives of Virology 155 (1): 133–146.  
  9. ^ Hill C, Booth T, et al. (1999). "The structure of a cypovirus and the functional organization of dsRNA viruses". Nature Structural Biology 6 (6): 565–9.  
  10. ^ Knipe D, Howley P, et al. (2006). Fields Virology. Philadelphia, Pa.: Wolters Kluwer, Lippincott Williams & Wilkins. p. 1855.  
  11. ^ Attoui, Houssam; Mertens, Peter. 2007.127-129V.v2.Spina-Sedoreovirinae. ICTV. pp. 1–9 http://talk.ictvonline.org/files/ictv_official_taxonomy_updates_since_the_8th_report/m/vertebrate-2008/1221.aspx. 
  12. ^ Deng, X. X.; Lü, L.; Ou, Y. J.; Su, H. J.; Li, G.; Guo, Z. X.; Zhang, R.; Zheng, P. R.; Chen, Y. G.; He, J. G.; Weng, S. P. (2012). "Sequence analysis of 12 genome segments of mud crab reovirus (MCRV)". Virology 422 (2): 185–194.  
  13. ^ Kibenge MJ, Iwamoto T, Wang Y, Morton A, Godoy MG, Kibenge FS (2013). "Whole-genome analysis of piscine reovirus (PRV) shows PRV represents a new genus in family Reoviridae and its genome segment S1 sequences group it into two separate sub-genotypes". Virol. J. 10: 230.  
  14. ^ Lal R, Harris D, Postel-Vinay S, de Bono J (October 2009). "Reovirus: Rationale and clinical trial update". Curr. Opin. Mol. Ther. 11 (5): 532–9.  
  15. ^ Kelland, K. (13 June 2012). "Cold virus hitches a ride to kill cancer: study". Reuters. Retrieved 17 June 2012. 
  16. ^ Thirukkumaran C, Morris DG (2009). "Oncolytic viral therapy using reovirus". Methods Mol. Biol. Methods in Molecular Biology 542: 607–34.  

External links

  • Viralzone: Reoviridae
  • ICTV: Reoviridae
  • Description of plant viruses: Reoviridae
  • ViPR: Reoviridae
  • "Reoviridae". NCBI Taxonomy Browser. 10880. 
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