Positive selection of ORF1 and ORF2 in hepatitis E virus genome

ObjectiveTo explore positive selection sites in ORF1 and ORF2 of hepatitis Evirus(HEV)genome.MethodsThirty-one complete genomes of types of HEV were retrieved from GenBank,and were aligned,corrected by codon with MEGA 3.1 software package.Phylogenetic tress were constructed with PHYLIP3.6 package.Adaptive evolution was analyzed with PAML 4.0 package.ResultsIt was revealed that purified evolution prevailed the ORF1 and ORF2 with ω of 0.029 and 0.024 respectively.Ninety-three percent of ORF1 sites and 98 percent of ORF1 sites were conservative with ω of 0.018 by neutral evolution model.No positive selection site was found in ORF1 or ORF2.ConclusionNo positive selection site was found in ORF1 or ORF2,which indicated that positive selection was not prevailing during HEV evolution.