title: Comprehensive analysis of the overall codon usage patterns in equine infectious anemia virus.
abstract: BACKGROUND
  Equine infectious anemia virus (EIAV) is an important animal model for understanding the relationship between viral persistence and the host immune response during lentiviral infections. Comparison and analysis of the codon usage model between EIAV and its hosts is important for the comprehension of viral evolution. In our study, the codon usage pattern of EIAV was analyzed from the available 29 full-length EIAV genomes through multivariate statistical methods.
  
  
  RESULTS
  Effective number of codons (ENC) suggests that the codon usage among EIAV strains is slightly biased. The ENC-plot analysis demonstrates that mutation pressure plays a substantial role in the codon usage pattern of EIAV, whereas other factors such as geographic distribution and host translation selection also take part in the process of EIAV evolution. Comparative analysis of codon adaptation index (CAI) values among EIAV and its hosts suggests that EIAV utilize the translational resources of horse more efficiently than that of donkey.
  
  
  CONCLUSIONS
  The codon usage bias in EIAV is slight and mutation pressure is the main factor that affects codon usage variation in EIAV. These results suggest that EIAV genomic biases are the result of the co-evolution of genome composition and the ability to evade the host's immune response.
authors.forename: Xin
authors.initials: X
authors.lastname: Yin
authors.forename: Yuezhi
authors.initials: Y
authors.lastname: Lin
authors.forename: Weigang
authors.initials: W
authors.lastname: Cai
authors.affiliation: Division of Livestock Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, PR China. weiiping@yahoo.com.cn.
authors.forename: Ping
authors.initials: P
authors.lastname: Wei
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Wang
mesh_terms: D003062:Codon / Q000032:analysis*; D019295:Computational Biology; D054884:Host-Pathogen Interactions; D004860:Infectious Anemia Virus, Equine / Q000235:genetics*; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D003062:Codon