Excavating New Facts from Ancient Hepatitis B Virus Sequences

Abstract

Recently, Muhlemann et al. (2018) and Krause-Kyora et al. (2018) discovered 15 ancient Hepatitis B virus (aHBV) sequences dating back to the Neolithic age (NA) and the Bronze age (BA). Being published simultaneously, neither of these studies could include sequences from the other for analyses. In the present research, aHBV sequences from these studies were collective re-analysed with reference to a comprehensive database comprising extant HBV diversity to understand their relatedness and role in the evolution of extant HBV diversity. Present analyses revealed several interesting findings on distribution, dispersal, phylogenetic and recombinational relatedness of ancient HBV to extant genotypes, which were not recognized previously. Several interesting recombination patterns were observed, which corroborated well with ancient human migration, shown by the human genetic studies. Present analyses suggest that comparable to the replacement of the Neolithic European farmer associated Y chromosome haplogroups by haplogroups associated with the steppe people during Steppe migration, HBV genotype associated with the early Neolithic European farming cultures was also replaced by the ancestral HBV genotype A probably carried by the migrating steppe people, and a variant of this genotype is the prevalent HBV genotype in contemporary European populations. Additionally, based on recent literature, this research also indicates that HBV genotype divergence estimates proposed by Muhlemann et al., and others cannot sufficiently explain distribution of certain extant HBV genotypes. Hence, an alternative possibility to explain long distance and trans-oceanic distribution of phylogenetically related HBV genotypes was reviewed and discussed in the light of currently available knowledge. Through this manuscript, novel and important findings of the present analyses are communicated.