Genetic variability of the S segment of Toscana virus

• This study was conducted on the genetic variability of the whole S segment of Toscana virus.
• Phylogenetic analysis demonstrates that TOSV A is the only genotype identified in Italy.
• A genome stability of Toscana virus over the years is shown.

Toscana virus (TOSV) was originally isolated in 1971 from a pool of Phlebotomus perniciosus sandflies collected in Grosseto province (Central Italy). Since its first isolation, several studies have been conducted in Italy and other Mediterranean countries in order to identify its possible animal reservoirs, spread of infection and genetic variability. Phylogenetic analysis conducted on TOSV genome demonstrated the co-circulation of two major lineages in the Mediterranean areas, TOSV A and TOSV B. This study reports the results of the genetic analysis of 32 viral strains isolated in Italy in the last 30 years from patients hospitalized with neurological disease, from sandflies and from the brain of a bat. The genetic diversity of TOSV was investigated by determining the sequences of the whole S segment. Phylogenetic analysis showed that TOSV A lineage represents the lineage circulating in Italy. Moreover, the current variability of lineage A is similar to that of lineage B.