Rhabdoviridae
From Free net encyclopedia
| Rhabdoviruses
Template:Taxobox begin placement virus Template:Taxobox group v entry | |
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| Order: | Mononegavirales |
| Family: | Rhabdoviridae |
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!Genera
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Vesiculovirus
Lyssavirus
Ephemerovirus
Cytorhabdovirus
Nucleorhabdovirus
Novirhabdovirus
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Rhabdoviruses are viruses belonging to the family Rhabdoviridae, which is in the order Mononegavirales. The name is derived from the Greek rhabdos meaning rod referring to the shape of the viral particles. Rhabdoviruses infect a broad range of hosts throughout the animal and plant kingdom. Animal rhabdoviruses infect insects, fish, and mammals, including humans.
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The Viruses
Rhabdoviruses carry their genetic material in the form of negative-sense single-stranded RNA. They typically carry genes for five proteins: large protein (L), glycoprotein (G), nucleoprotein (N), nonstructural protein (NS), and matrix protein (M). Rhabdoviruses that infect vertebrates are bullet-shaped.
The following genera are included here:
- Genus Cytorhabdovirus; type species: Lettuce necrotic yellows virus
- Genus Ephemerovirus; type species: Bovine ephemeral fever virus
- Genus Lyssavirus; type species: Rabies virus
- Genus Novirhabdovirus; type species: Infectious hematopoietic necrosis virus
- Genus Nucleorhabdovirus; type species: Potato yellow dwarf virus
- Genus Vesiculovirus; type species: Vesicular stomatitis Indiana virus
In addition to the above, there are a large number of rhabdoviruses that have not yet been assigned to a genus.
Replication
Replication of rhabdoviruses occurs in the cytoplasm. In order for replication, both the L and NS protein must be expressed to regulate transcription. Transcription results in five monocistronic mRNAs being produced because the intergenic sequences act as both termination and promoter sequences for adjacent genes. Subsequently, the mRNAs are then processed to introduce a 5’ cap and a 3’ polyadenylated tail to each of the molecules. This structure is homologous to cellular mRNAs and can thus be translated by cellular ribosomes to produce both structural and non-structural proteins.
Genomic replication is not as well understood. It is believed that, once the various proteins have been synthesised, a full length genomic copy is generated and subsequently replicated from a positive sense intermediate. It has been shown that the L+P polymerase complex is necessary. Nevertheless cellular factors are also required, but these are not fully understood.
Replication characteristically occurs in an inclusion body within the cytoplasm, from where they bud through various cytoplasmic membranes and the outer membrane of the cell. This process results in the acquisition of the M + G proteins, responsible for the characteristic bullet- shaped morphology of the virus.
Prototypical Rhabdoviruses
The prototypical and best studied rhabdovirus is vesicular stomatitis virus. Since it is easy to grow in the laboratory, it is a preferred model system to study the biology of Rhabdoviruses, and Mononegavirales in general.
The mammalian disease Rabies is caused by Lyssavirus, of which several strains have been identified.
Further reading
- J.K. Rose and M.A. Whitt (2001). Rhabdoviridae: The viruses and their replication. In: D.M. Knipe and P.M. Howley, ed., Field's Virology, vol. 1, pp. 1221-1244. Lippincott Williams & Wilkins, Philadelphia, 4th edition.
- R.R. Wagner, ed. (1987). The Rhabdoviruses. Plenum Press, New York.fr:Rhabdoviridae