Time-scaled phylogenies of both genome segments of infectious bursal disease virus suggest multiple re-assortment events in its evolutionary history

Abstract

Infectious bursal disease virus (IBDV) causes an immunosuppressive disease in chickens, resulting in serious economic impacts in the worldwide poultry industries. The evolutionary history of IBDV was puzzled by the phylogenetic discordance between the two genome segments for years. In this study, phylogenies of segments A and B were reconstructed to estimate the earlier divergence events in the evolutionary histories of both segments. The evolutionary rates and the time of most recent common ancestor (tMRCA) results of individual lineage in each segment were estimated independently. These evolutionary rates and tMRCA results were implemented as prior timestamps for the reconstruction of the phylogenies of the two segments. The earlier divergence events of various genotypes from the two phylogenies jointly suggest multiple re-assortment events in the evolutionary history of IBDV. This study is expected to provide a better understanding on the evolutionary history of IBDV and highlight the multiple occurrences of reassortment events which shaped the phylogeny of IBDV nowadays.