Figure. Phylogenetic analysis of hepatitis E virus (HEV) based on the complete genome sequences of HEVs using the neighbor-joining method with MEGA 4.0 software (http://www.megasoftware.net). Black diamond indicates the newly identified yak HEV sequence from Qinghai, China (GenBank accession no. KF736234). Another 18 sequences were collected from GenBank, including 7 sequences of genotype 4 (GU119961, JQ740781, JQ655735, AB291965, AB602440, FJ763141, GU206559), 6 of genotype 3 (AF455784, FJ705359, AY575859, HQ389543, AB291963, FJ527832), 1 of genotype 2 (M74596), and 4 of genotype 1 (AY204877, AF051352, JQ655734, JF443726). Bootstrap values of >50% are indicated for the corresponding nodes based on a bootstrapping with 1,000 replicates. GenBank accession numbers and geographic and animal species origin are shown. Scale bar indicates nucleotide substitutions per site.