Analysis of 3' and 5' ends of N and NSs messenger RNAs of Toscana Phlebovirus.

The 5' and 3' ends of N and NSs mRNAs, transcribed from the S segment of Toscana Phlebovirus, were analyzed by oligonucleotide primer extension and S1 nuclease mapping procedures. The results showed that both mRNAs acquired, at their 5' end, approximately 9-15 nucleotides not present in the viral template, suggesting an initiation transcription mechanism similar to the one described for influenza virus. Furthermore, the 3' ends of the two mRNAs were located in a sequence motif conserved in the S segment of two other Phleboviruses, the Rift Valley Fever and Sandfly Fever Sicilian viruses. This finding suggests the possible involvement of this sequence in the mechanism of transcription termination.