38 Characterization of Synonymous Codon Usage Bias in the UL7 Gene of Duck Plague Virus

The Duck Plague Virus (DPV) UL7 gene was identified by constructing the DPV genomic library in our laboratory, and we analyzed the codon usage of DPV UL7 gene by employing CAI, CHIPS and CUSP program of EMBOSS. The results showed that codon usage bias of DPV UL7 gene was strong bias towards the synonymous with A and T at the third codon position. And obvious differences of the codon usage bias in the DPV UL7gene and reference herpesviruses by ENC and CG3s. The amino acids codon usage bias of DPV UL7 gene and the UL7-like genes of 30 other reference herpesviruses were analyzed, the phylogentic analysis revealed that DPV was evolutionarily closer to the avian Alphaherpesvirinae and all of them are highly expressed genes. Moreover, there is small variation in codon usage pattern among reference herpesviruses. In addition, the codon usage bias of DPV UL7 gene was compared with those of E. coli, yeast and human. There are 26 codons showing distinct usage differences between DPV and E. coli, 18 codons between DPV and yeast, 22 codons between DPV and human. Therefore, the yeast expression system is more suitable for heterologous expression of the DPV UL7 gene.