Toscana phlebovirus

Toscana phlebovirus (TOSV) is an arbovirus (arthropod-borne virus) belonging to Bunyavirales, an order of negative-stranded, enveloped RNA viruses. The virus can be transmitted to humans by the bite of an infected sandfly of the genus Phlebotomus.[1] Toscana is not normally associated with disease, as indicated by high seroprevalence rates (up to 25%) in endemic areas,[2] but in common with other sandfly transmitted viruses such as Naples virus and Sicilian virus, infection may result in Pappataci fever, an illness with mild fever, headache and myalgia. In serious cases that go undiagnosed, acute meningitis, meningoencephalitis and encephalitis may occur. There is no specific treatment for infection, so treatment is supportive, reducing the severity of symptoms until the immune system has cleared the infection.[3]

Toscana phlebovirus
Virus classification Edit this classification
(unranked): Virus
Realm: Riboviria
Kingdom: Orthornavirae
Phylum: Negarnaviricota
Class: Ellioviricetes
Order: Bunyavirales
Family: Phenuiviridae
Genus: Phlebovirus
Species:
Toscana phlebovirus
Synonyms
  • Toscana virus

The virus is found in most countries that border the Mediterranean Sea, with the highest incidence in Italy. Infection rates peak during the summer time as sandfly populations grow more abundant.[4]

Virology

Structure and genome

TOSV has a spherical, enveloped body with an 80–120 nm diameter. The genome is encased in a nucleocapsid and consists of negative-sense RNA broken into three segments, termed L, M and S. L is about 6,400 nucleotides in length, M about 4,200 nucleotides in length, and S about 1,900 nucleotides in length. L encodes for the viral polymerase, M encodes for structural glycoproteins and S encodes for nucleic proteins.

Diagnosis

Laboratory diagnosis of TOSV infection can be performed through the use of ELISA, immunofluorescence and/or neutralization tests,[5] but reverse transcription, real-time polymerase chain reaction assays are preferred because they are less time-consuming and reduce the risk of contamination.[5][6]

Epidemiology

This virus is a leading cause of acute meningitis between May and October in Central Italy and in other northern Mediterranean countries (Croatia, France, Greece, Portugal and Spain) as well as several of the eastern Mediterranean countries (Cyprus and Turkey). It is among the 3 most prevalent viruses associated with meningitis during the warm seasons: the other two are enteroviruses and herpesviruses.

History

Toscana virus (TOSV) was first isolated in 1971 from Phlebotomus perniciosus and Phlebotomus perfiliewi in Monte Argentario (Grosseto, Tuscany).[7]

References
  1. Valassina, M.; Cusi, M. G.; Valensin, P. E. (2003). "A Mediterranean arbovirus: The Toscana virus". Journal of NeuroVirology. 9 (6): 577–583. doi:10.1080/jnv.9.6.577.583. PMID 14602570.
  2. Braito, A.; Corbisiero, R.; Corradini, S.; Marchi, B.; Sancasciani, N.; Fiorentini, C.; Ciufolini, M. G. (1997). "Evidence of Toscana virus infections without central nervous system involvement: A serological study". European Journal of Epidemiology. 13 (7): 761–764. doi:10.1023/A:1007422103992. PMID 9384264. S2CID 11973850.
  3. Arboviral Infections (Report). Virginia Department of Health.
  4. Valassina, M.; Cusi, M. G.; Valensin, P. E. (2003). "A Mediterranean arbovirus: The Toscana virus". Journal of Neurovirology. 9 (6): 577–583. doi:10.1080/jnv.9.6.577.583. PMID 14602570.
  5. Cusi, M. G.; Savellini, G. G. (2011). "Diagnostic tools for Toscana virus infection". Expert Review of Anti-infective Therapy. 9 (7): 799–805. doi:10.1586/eri.11.54. PMID 21810052. S2CID 46365705.
  6. Pérez-Ruiz, M.; Collao, X.; Navarro-Marí, J. -M. A.; Tenorio, A. (2007). "Reversetranscription, real-time PCR assay for detection of Toscana virus". Journal of Clinical Virology. 39 (4): 276–281. doi:10.1016/j.jcv.2007.05.003. PMID 17584525.
  7. Charrel RN, Bichaud L, de Lamballerie X (2013). "Emergence of Toscana virus in the Mediterranean area". World J Virol. 1 (5): 135–141. doi:10.5501/wjv.v1.i5.135. PMC 3782275. PMID 24175218.
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