Dengue virus type 4 evolution and genomics: A bioinformatic approach

Dengue is becoming the most devastating endemic disease in the last few years all over the world. Four serotypes DENV1, DENV2, DENV3 and DENV4 show strong adaptation against host defence. DENV4 is phylogenetically most divergent serotype and highlights the importance of the study about evolution and genomics of DENV4 genome. Overall, study of codon usage pattern at gene level and the effect of mutational bias, natural selection, translational selection and gene length were estimated. A multivariate statistical analysis showed the conservation of codon usage pattern among phylogenetically closely related DENV4 genomes. For compositional constraint, most of the preferred codons in DENV4 genes contain 'A' and/or 'T' at 3 rd position. Moreover, mutational bias and gene length were also functioning for the variation in codon usage. Pyrimidines ending preferred codons were slightly numerous in highly expressed genes, but codon usage bias was higher in non-structural genes than structural one, which was the evidence for the absence of the effect of translational selection on codon usage variation of DENV4 genome. The study is helpful to understand the evolution of DENV4 genome and gradual change in their pathogenicity.