Fig. 4. Analysis of the virulence associated with the NSs of RVFV MP12.

A) Characterization of S segment by Taq1α digestion. S segment RT-PCR carried out on total RNA extracted at 15h p.i. from Vero cells infected by ZH548, MP12, rZH, rZH-SMP12 or rZH-NSsMP12 at a moi=3. Schematic representation of the position of Taq1α in the S segment of ZH548 and MP12. The size of digestion products for ZH548 and rZH are indicated. B) Inhibition of the IFN-β mRNA transcription by these viruses except for the rZHΔNSs. IFN-β- and GAPDH-specific RT-PCR performed on total RNA extracted at 8h p.i. from L929 cells infected at a moi=3 by ZH548, MP12, or the recombinant RVFV. C) Survival curves of 4 to 5 week old mice (Swiss) infected with 10⁴ pfu of each RVFV. The experiment was carried out using lots of 12 mice.