Research Article

Virologica Sinica

, Volume 27, Issue 5, pp 303-315

Characterization of synonymous codon usage bias in the pseudorabies virus US1 gene

  • Meili LiAffiliated withDepartment of Pathogenic Biology and Immunology, Guangzhou Medical University
  • , Zhiyao ZhaoAffiliated withDepartment of Pathogenic Biology and Immunology, Guangzhou Medical University
  • , Jianhong ChenAffiliated withDepartment of Veterinary Medicine, Foshan Science and Technology University
  • , Bingyun WangAffiliated withDepartment of Veterinary Medicine, Foshan Science and Technology University
  • , Zi LiAffiliated withDepartment of Pathogenic Biology and Immunology, Guangzhou Medical University
  • , Jian LiAffiliated withDepartment of Pathogenic Biology and Immunology, Guangzhou Medical University
  • , Mingsheng CaiAffiliated withDepartment of Veterinary Medicine, Foshan Science and Technology University Email author 

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Abstract

In the present study, we examined the codon usage bias between pseudorabies virus (PRV) US1 gene and the US1-like genes of 20 reference alphaherpesviruses. Comparative analysis showed noticeable disparities of the synonymous codon usage bias in the 21 alphaherpesviruses, indicated by codon adaptation index, effective number of codons (ENc) and GC3s value. The codon usage pattern of PRV US1 gene was phylogenetically conserved and similar to that of the US1-like genes of the genus Varicellovirus of alphaherpesvirus, with a strong bias towards the codons with C and G at the third codon position. Cluster analysis of codon usage pattern of PRV US1 gene with its reference alphaherpesviruses demonstrated that the codon usage bias of US1-like genes of 21 alphaherpesviruses had a very close relation with their gene functions. ENc-plot revealed that the genetic heterogeneity in PRV US1 gene and the 20 reference alphaherpesviruses was constrained by G+C content, as well as the gene length. In addition, comparison of codon preferences in the US1 gene of PRV with those of E. coli, yeast and human revealed that there were 50 codons showing distinct usage differences between PRV and yeast, 49 between PRV and human, but 48 between PRV and E. coli. Although there were slightly fewer differences in codon usages between E.coli and PRV, the difference is unlikely to be statistically significant, and experimental studies are necessary to establish the most suitable expression system for PRV US1. In conclusion, these results may improve our understanding of the evolution, pathogenesis and functional studies of PRV, as well as contributing to the area of herpesvirus research or even studies with other viruses.

Keywords

Pseudorabies virus US1 gene Alphaherpesvirus Codon usage bias