Fig. 4

ENC–GC3 plots displaying the relationship between GC3s and effective number of codon (ENC) for three HEV ORFs. All three HEV ORFs were analyzed together regardless of the genotype and the data were colored according to the ORF (a). Then, the ORF1s, 2 s and 3 s were analyzed separately and the data were colored according the different genotypes (b, c and d, respectively). The solid curve indicates the expected codon usage if GC compositional constraints alone justify the codon usage bias