Immunoblot detection of antibodies to Toscana virus.

Sera from patients with sandfly fever caused by Toscana virus (TOSV) infection were tested by immunoblot for specific antibody response to TOSV derived from infected Vero-E6 cells. The 28 kDa TOSV nucleoprotein (N) was identified as the major immunodominant protein recognized by immunoblot. In sera of patients with acute TOSV infection, specific antibodies of the IgM, IgA, and IgG class were detected. Using sandfly fever virus, serotypes Sicilian (SFSV) and Naples (SFNV), as antigens for immunoblot, TOSV antibody-positive sera cross-reacted with the corresponding N proteins. These sera reacted for IgM and IgG by SFSV immunoblot, and for IgM by SFNV immunoblot. The diagnosis of sandfly fever may be confirmed by TOSV immunoblot.