Host-Independent Evolution and a Genetic Classification of the Hepadnavirus Family Based on Nucleotide Sequences

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 86; no. 18; pp. 7059 - 7062
• Main Authors: Orito, Etsuro, Mizokami, Masashi, Ina, Yasuo, Moriyama, Etsuko N., Kameshima, Nobutoshi, Yamamoto, Masahiko, Gojobori, Takashi
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.09.1989; National Acad Sciences
• Subjects: Animals; Bacteriology; Base Sequence; Biological and medical sciences; Biological Evolution; DNA, Viral - genetics; Evolution; Evolutionary genetics; Fundamental and applied biological sciences. Psychology; Genes, Viral; Genomes; Hepadnaviridae; Hepatitis B virus; Hepatitis B virus - classification; Hepatitis B virus - genetics; Humans; Microbiology; Molecular Sequence Data; Nucleotide sequences; Open reading frames; Phylogenetics; Phylogeny; Systematics; Viruses; Virus; Phylogeny; Substitution; Nucleotide sequence; Hepadnaviridae; Biological evolution
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.86.18.7059

An analysis of molecular phylogeny was undertaken to examine whether the evolution of the hepadnavirus family is host-dependent. Using the nucleotide sequences of 18 strains, we constructed phylogenetic trees. The trees obtained show that all 12 strains of hepatitis B virus can be classified into four subgroups that are not compatible with conventional subtypes. We estimated the rate of synonymous (silent) substitution for hepatitis B virus to be 4.57 × 10-5 per site per year. Applying this rate to the phylogenetic tree, we estimated that duck hepatitis B virus diverged from a common ancestor about 30,000 years ago at the earliest, that woodchuck hepatitis virus and ground squirrel hepatitis virus diverged about 10,000 years ago, and that hepatitis B virus diverged within the last 3000 years. Because these divergence times of the viruses are much more recent than those of the host species, it suggests that the hepadnavirus family evolved independently of host-species divergence.