Synthesis of cDNA was performed on the nucleic acid extract using the RevertAid First Strand cDNA Synthesis Kit (ThermoFisher Scientific, Gent, Belgium). The cDNA was used to amplify the four known TVVs by means of previously described type specific primers: TVV1F2875 (5′-ATT AGC GGT GTT TGT GAT GCA-3′) and TVV1R3443 (5′-CTA TCT TGC CAT CCT GAC TC-3′), TVV2F1401 (5′-ATT AGC GGT GTT TGT GAT GCA-3′) and TVV2R1953b (5′-GGT TCG TGG AAG CGG TTG ATG A-3′), TVV3F1474 (5′-CTA CCA AGA AGG AGG CTT GA-3′) and TVV3R2025b (5′-GGT TCG TGG AAG CGG TTG ATG A-3′), and TVV4F1338 (5′-ATG CCA GTT GCT TTC CG-3′) and TVV4R1834 (5′-TTC CCC AAT AGT TAT CAG-3′) . The amplification conditions were: 5 min at 95 °C, 40 cycles of 30 s at 95 °C, 30 s at 50 °C and 45 s at 72 °C, followed by 7 min at 72 °C. The PCR products were visualized by electrophoresis as described above.