Figure 3. Phylogenetic relationships of the S (small), M (medium), and L (large) RNA segments of Rift Valley fever viruses. Strains isolated in Mauritania (gray shading) are designated H1MAU03 and H2MAU03, according to previous abbreviation guidelines (24). Nucleotide sequences of these segments (S, M, and L) have been submitted to GenBank with the following accession nos., respectively: EF160113, EF160116, and EF160117 for H1MAU03; EF160114, EF160115, and EF160118 for H2MAU03. Branch lengths are proportional to the number of substitutions per site.