Lyssavirus

This article is about the rabiform virus. For the hemorrhagic fever-causing virus, see Lassa virus.
Lyssavirus
Colored transmission electron micrograph of Australian bat lyssavirus. The bullet-like objects are the virus, and some of them are budding off from a cell.
Virus classification
Group: Group V ((-)ssRNA)
Order: Mononegavirales
Family: Rhabdoviridae
Genus: Lyssavirus
Type Species

Rabies virus

Lyssavirus is a genus of RNA viruses in the order Mononegavirales, in the family Rhabdoviridae. Humans, mammals, and vertebrates serve as natural hosts. There are currently 14 species in this genus including the type species Rabies virus.[1][2] Lyssavirus (from Lyssa, the Greek goddess of madness, rage, and frenzy) includes the rabies virus traditionally associated with the disease.

Taxonomy

Group: ssRNA(-)

[2]

Virology

Structure

Viruses in Lyssavirus are enveloped, with bullet shaped geometries. These viruses are about 75 nm wide and 180 nm long.[1] Lyssaviruses have helical symmetry, so their infectious particles are approximately cylindrical in shape. This is typical of plant-infecting viruses. Human-infecting viruses more commonly have cubic symmetry and take shapes approximating regular polyhedra.

The structure consists of a spiked outer envelope, a middle region consisting of matrix protein M, and an inner ribonucleocapsid complex region, consisting of the genome associated with other proteins.

Genome

Lyssavirus genome consists of a negative-sense, single-stranded RNA molecule that encodes five viral proteins: polymerase L, matrix protein M, phosphoprotein P, nucleoprotein N, and glycoprotein G. Genomes are linear, around 11kb in length.[1]

Based on recent phylogenetic evidence, lyssaviruses are categorized into seven major species. In addition, five species recently have been discovered: West Caucasian bat virus, Aravan virus, Khujand virus, Irkut virus and Shimoni bat virus.[3][4] The major species include rabies virus (species 1), Lagos bat virus (species 2), Mokola virus (species 3), Duvenhage virus (species 4), European Bat lyssaviruses type 1 and 2 (species 5 and 6), and Australian bat lyssavirus (species 7).[5]

Based on biological properties of the viruses, these species are further subdivided into phylogroups 1 and 2. Phylogroup 1 includes genotypes 1, 4, 5, 6, and 7, while phylogroup 2 includes genotypes 2 and 3. The nucleocapsid region of lyssavirus is fairly highly conserved from genotype to genotype across both phylogroups; however, experimental data have shown the lyssavirus strains used in vaccinations are only from the first species(i.e. classic rabies).[5]

Genus Structure Symmetry Capsid Genomic Arrangement Genomic Segmentation
LyssavirusBullet-shapedEnvelopedLinearMonopartite

Life Cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by attachment of the viral G glycoproteins to host receptors, which mediates clathrin-mediated endocytosis. Replication follows the negative stranded RNA virus replication model. Negative stranded RNA virus transcription, using polymerase stuttering is the method of transcription. The virus exits the host cell by budding, and tubule-guided viral movement. Human, mammals, and vertebrates serve as the natural host. Transmission routes are zoonosis and bite.[1]

Genus Host Details Tissue Tropism Entry Details Release Details Replication Site Assembly Site Transmission
LyssavirusHumans; mammalsNeuronsClathrin-mediated endocytosisBuddingCytoplasmCytoplasmZoonosis; animal bite

Epidemiology

Species 1, classic rabies, is prevalent throughout most of the world and can be carried by any warm blooded mammal. The other species (2 through 7) have much less diversity in carriers. Only select hosts can carry each of the viral species. Also, these other species are particular only to a specific geographic area. Bats are known to be an animal vector for all identified lyssavirus species except the Mokola virus.[6]

See also

References

  1. 1 2 3 4 "Viral Zone". ExPASy. Retrieved 15 June 2015.
  2. 1 2 ICTV. "Virus Taxonomy: 2014 Release". Retrieved 15 June 2015.
  3. ↑ Virus Taxonomy: 2013 Release. ictvonline.org
  4. ↑ Kuzmin, I.; Hughes, G.; Botvinkin, A.; Orciari, L.; Rupprecht, C. (2005). "Phylogenetic relationships of Irkut and West Caucasian bat viruses within the genus and suggested quantitative criteria based on the N gene sequence for lyssavirus genotype definition". Virus Research 111 (1): 28–25. doi:10.1016/j.virusres.2005.03.008. PMID 15896400.
  5. 1 2 Badrane, H.; Bahloul, C.; Perrin, P.; Tordo, N. (2001). "Evidence of Two Lyssavirus Phylogroups with Distinct Pathogenicity and Immunogenicity". Journal of Virology 75 (7): 3268–3276. doi:10.1128/JVI.75.7.3268-3276.2001. PMC 114120. PMID 11238853.
  6. ↑ WHO Rabnet/CDC Map Production (2008). "Rabies, countries or areas at risk". World Health Organization.

See also

External links

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