Characterization of Codon Usage Bias in the UL55 Gene of Duck Enteritis Virus

Abstract

The analysis of codon usage may improve our understanding of the evolution and pathogenesis of DEV（Duck enteritis virus） and allow reengineering of target gene to improve their expression for gene therapy.In this study,we calculated the codon usage bias in DEV UL55 gene and performed a comparative analysis of synonymous codon usage patterns in other 26 related viruses by EMBOSS CUSP program and Codon W on line.Moreover,statistical methods were used to investigate the correlations of these related parameters. By comparing synonymous codon usage patterns in different viruses,we observed that synonymous codon usage pattern in these virus is virus specific and phylogenetically conserved, with a strong bias towards the codons with A and T at the third codon position. Phylogenetic analysis based on codon usage pattern suggested that DEV UL55 gene was clustered with the avian Alphaherpesvirus but diverged to form a single branch. The Neutrality-plot suggested GC12 and GC3s adopt the same mutation pattern,meanwhile,the ENC-plot revealed that the genetic heterogeneity in UL55 genes is constrained by the G+C content, while translational selection and gene length have no or micro effect on the variations of synonymous codon usage in these virus genes.Furthermore, we compared the codon preferences of DEV with those of E. coli, yeast and Homo sapiens.Data suggested the eukaryotes system such as human system may be more suitable for the expression of DEV UL55 gene in vitro. If the yeast and E. coli expression system are wanted for the expression of DEV UL55 gene ,codon optimization of the DEV UL55 gene may be required.