Phylogeny of the Genus <i>Flavivirus</i>

TLDR

The study aimed to determine the genetic relationships among Flavivirus species and compare molecular phylogeny with serologic classification. The authors performed a comprehensive phylogenetic analysis using bootstrap support and pairwise nucleotide sequence identity to classify Flavivirus into clusters, clades, and species. The analysis revealed that Flavivirus evolved from a non‑vector ancestor into vector‑borne lineages, with tick‑borne and mosquito‑borne clusters diverging sequentially, and that the resulting clades align with antigenic complexes while resolving taxonomic ambiguities.

Abstract

We undertook a comprehensive phylogenetic study to establish the genetic relationship among the viruses of the genus Flavivirus and to compare the classification based on molecular phylogeny with the existing serologic method. By using a combination of quantitative definitions (bootstrap support level and the pairwise nucleotide sequence identity), the viruses could be classified into clusters, clades, and species. Our phylogenetic study revealed for the first time that from the putative ancestor two branches, non-vector and vector-borne virus clusters, evolved and from the latter cluster emerged tick-borne and mosquito-borne virus clusters. Provided that the theory of arthropod association being an acquired trait was correct, pairwise nucleotide sequence identity among these three clusters provided supporting data for a possibility that the non-vector cluster evolved first, followed by the separation of tick-borne and mosquito-borne virus clusters in that order. Clades established in our study correlated significantly with existing antigenic complexes. We also resolved many of the past taxonomic problems by establishing phylogenetic relationships of the antigenically unclassified viruses with the well-established viruses and by identifying synonymous viruses.