Genetic diversity of Toscana virus

Abstract

Distribution of Toscana virus (TOSV) is evolving with climate change, and pathogenicity may be higher in nonexposed populations outside areas of current prevalence (Mediterranean Basin). To characterize genetic diversity of TOSV, we determined the coding sequences of isolates from Spain and France. TOSV is more diverse than other well-studied phleboviruses (e.g.,Rift Valley fever virus).

Figure 1

Histogram showing distribution of nucleotide pairwise (p) distances in the medium segment of Toscana virus. p distances are for nucleotides; frequencies are for intervals of 0.01. Validity of this method was confirmed by analysis of variance, comparing the scores of sequence comparisons within genotypes to those between genotypes. Black bars indicate intralineage distribution; white bars indicate interlineage distribution.

Figure 2

Phylogenetic analysis of Toscana virus (TOSV) strains. Coding regions for A) nonstructural (NS) gene, B) nucleoprotein (N) gene, C) medium (M) gene, and D) large (L) gene were studied by using distance MEGA (www.megasoftware.net); relationships between different strains are shown. Each sequence used shows GenBank accession number followed by name of the virus according to the International Committee on Taxonomy of Viruses and the corresponding strain. Proposed virus genotypes (TOSV from Italy, A; TOSV from Spain, B) are indicated. For TOSV, 4 lineages (G1 to G4) are shown, and for RVFV, 7 lineages (A to G) are shown, as previously described (2,8). The sequences obtained in this work are TOSVFR (TOSV H/IMTSSA), TOSVGH (TOSV ESH 62100), and TOSVGR (TOSV EsPhGR40). RVFV, Rift Valley fever virus; PTV, Punta Toro virus; SFSV, sandfly fever Sicilian virus; UUKV, Uukuniemi virus; SFNV, Sandfly fever Naples virus; FRIV, Frijoles virus; ICOV, Icoaraci virus; JOAV, Joa virus; BELTV, Belterra virus; SLBOV, Salobo virus; BUEV, Buenaventura virus. Scale bars indicate nucleotide substitutions per site.