Sindbis virus (SINV) is a member of the ''

Togaviridae {{Commonscat, Viruses by family This category is for articles about virus families (or redirects to such articles). There should be no subcategories. families Families (biology) ...

'' family, in the '' Alphavirus'' genus. The virus was first isolated in 1952 in

Cairo Cairo ( ; , ) is the Capital city, capital and largest city of Egypt and the Cairo Governorate, being home to more than 10 million people. It is also part of the List of urban agglomerations in Africa, largest urban agglomeration in Africa, L ...

, Egypt. The virus is transmitted by

mosquitoes Mosquitoes, the Culicidae, are a family of small flies consisting of 3,600 species. The word ''mosquito'' (formed by '' mosca'' and diminutive ''-ito'') is Spanish and Portuguese for ''little fly''. Mosquitoes have a slender segmented body, ...

(''

Culex ''Culex'' or typical mosquitoes are a genus of mosquitoes, several species of which serve as vectors of one or more important diseases of birds, humans, and other animals. The diseases they vector include arbovirus infections such as West Nil ...

'' and '' Culiseta''). SINV is linked to

Pogosta ''Pogost'' (, from Old East Slavic: погостъ) is a Russian language, Russian historical term which has had several meanings. In modern Russian, it typically refers to a rural church and graveyard. It has also been borrowed into Latgalian l ...

diseaseKurkela S, Manni T, Vaheri A, Vapalahti O
Causative agent of Pogosta disease isolated from blood and skin lesions
Emerg Infect Dis erial on the Internet Published 2004 May. (accessed 2007-10-16). (

Finland Finland, officially the Republic of Finland, is a Nordic country in Northern Europe. It borders Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bothnia to the west and the Gulf of Finland to the south, ...

), Ockelbo disease (

Sweden Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...

) and Karelian fever (

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

). In humans, the symptoms include

arthralgia Arthralgia () literally means ' joint pain'. Specifically, arthralgia is a symptom of injury, infection, illness (in particular arthritis), or an allergic reaction to medication Medication (also called medicament, medicine, pharmaceuti ...

rash A rash is a change of the skin that affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracke ...

and

malaise In medicine, malaise is a feeling of general discomfort, uneasiness or lack of wellbeing and often the first sign of an infection or other disease. It is considered a vague termdescribing the state of simply not feeling well. The word has exist ...

. Sindbis virus is widely and continuously found in insects and vertebrates in Eurasia, Africa, and Oceania. Clinical infection and disease in humans however has almost only been reported from Northern Europe (Finland, Sweden, Russian Karelia), where SINV is endemic and where large outbreaks occur intermittently. Cases are occasionally reported in Australia, China, and South Africa. SINV is an

arbovirus Arbovirus is an informal name for any virus that is Transmission (medicine), transmitted by arthropod Vector (epidemiology), vectors. The term ''arbovirus'' is a portmanteau word (''ar''thropod-''bo''rne ''virus''). ''Tibovirus'' (''ti''ck-''bo ...

, it is arthropod-borne, and it is maintained in nature by transmission between

vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

(bird) hosts and

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

(mosquito) vectors. Humans are infected with Sindbis virus when bitten by an infected mosquito.

Virus physiology

Structure, genome and replication

Sindbis viruses are enveloped particles with an icosahedral

capsid A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or m ...

, with a positive single stranded

RNA Ribonucleic acid (RNA) is a polymeric molecule that is essential for most biological functions, either by performing the function itself (non-coding RNA) or by forming a template for the production of proteins (messenger RNA). RNA and deoxyrib ...

genome, with an approximate size of 11.7 kb. The RNA has a 5'-cap and 3'-polyadenylated tail, and therefore serves directly as messenger RNA (

mRNA In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein. mRNA is ...

) in a host cell. The genome encodes four non-structural proteins, the capsid, and two envelope proteins. This is characteristic of all Togaviruses. Replication is

cytoplasmic The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, including the organelles and excluding the nucleus in eukaryotic cells. The material inside the nucleus of a eukaryotic cell and ...

and rapid. The genomic RNA is partially translated at the 5' end to produce the non-structural proteins which are then involved in genome replication and the production of new genomic RNA and a shorter sub-genomic RNA strand. This sub-genomic strand is translated into the structural proteins. The viruses assemble at the host cell surfaces and acquire their

envelope An envelope is a common packaging item, usually made of thin, flat material. It is designed to contain a flat object, such as a letter (message), letter or Greeting card, card. Traditional envelopes are made from sheets of paper cut to one o ...

through

budding Budding or blastogenesis is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. For example, the small bulb-like projection coming out from the yeast cell is kno ...

. A non-coding RNA element has been found to be essential for Sindbis virus genome replication. Recombination has been demonstrated between

s of Sindbis virus. The mechanism of recombination appears to be template switching (copy choice) during RNA replication.

References

MicrobiologyBytes: Togaviruses

��ICTVdB—The Universal Virus Database, version 4.

External links

Virus Pathogen Database and Analysis Resource (ViPR): Togaviridae
{{Taxonbar, from=Q2302993 Alphaviruses

Virus physiology

Structure, genome and replication

See also

References

External links