A recombinant Toscana virus nucleoprotein in a diagnostic immunoblot test system

Sandfly fever, a vector-borne disease endemic in the Mediterranean region, is caused by Toscana virus (TOS). The disease is increasingly important as a travel-related infection. Serological diagnosis is currently dependent on viral antigens derived from TOS-infected cell cultures. In this study, we report the cloning and expression of the TOS nucleoprotein (N) in Escherich ia coli and evaluation of the recombinant (r) TOS N protein as an antigen f or immunoblot assays. The TOS N gene was amplified by reverse-transcriptase polymerase chain reaction and cloned into the bacterial expression vector pTrcHis-A. Sera with known TOS antibody status were used to evaluate the im munoblot assay. The expressed rTOS N protein was purified and used as antig en for immunoblots. By recombinant immunoblot, the TOS antibody status (IgM and/or IgG) of the test panel was correctly identified. No cross-reactivit y was detected. The rTOS N protein is useful as an antigen for immunoblot a ssays, and will enable more laboratories to perform TOS antibody diagnosis.