Due to the exotic origin of the virus, the potential for the aerosol transmission [9, 10, 11, 12] and serious consequences for humans and livestocks, wild-type (wt) RVFV is classified as a Risk Group 3 pathogen, that needs to be handled in a high-containment facility, e.g., a biosafety level (BSL)-4 laboratory, whereas a highly attenuated MP-12 strain of RVFV, produced after 12 serial passages of wt RVFV ZH548 in MRC-5 cells in the presence of 5fluorouracil [13] , is a Risk Group 2 pathogen. RVFV, which belongs to the genus Phlebovirus, family Bunyaviridae, is a negative-stranded RNA virus carrying a single-stranded, tripartite RNA genome composed of S, M and L segments [14] . The S segment encodes N and NSs genes and uses an ambi-sense strategy to express the N and NSs proteins in infected cells; N mRNA encoding N protein is transcribed from the viral-sense (negative-sense) S segment, while NSs mRNA encoding NSs protein is transcribed from the antiviral-sense (positive-sense) S segment. Monocistronic M mRNA and L mRNA are transcribed from the viral-sense M and L segments, respectively. M mRNA has one large open-reading frame (ORF) which encodes the nonstructural NSm protein, a 78-kDa glycoprotein and two major viral structural glycoproteins, Gn and Gc [15, 16] . L mRNA encodes L protein, a viral RNA-dependent RNA polymerase. Both N and L proteins are required for viral RNA synthesis, while Gn and Gc function as envelope proteins [14] . NSm and NSs, both nonstructural proteins, are dispensable for viral replication in cell cultures [17, 18, 19, 20] , but are involved in viral pathogenesis [21, 22, 23] .