Phylogenetic analysis based on the nucleotide sequence of the M segment of viruses belonging to the family Bunyaviridae referred to in this review. Phylogenetic analyses were performed by the neighbor-joining method with MEGA software, version 4 http://www.megasoftware.net/. Bootstrap probabilities of each node were calculated with 1,000 replicates. Scale bars indicate a genetic distance of 0.05-nt substitutions per site. The Chinese isolates are designated by boldface type in red.