title: Subgenotype reclassification of genotype B hepatitis B virus.
abstract: BACKGROUND
  Nine subgenotypes from genotype B have been identified for hepatitis B virus (HBV). However, these subgenotypes were less conclusive as they were often designated based on a few representative strains. In addition, subgenotype B6 was designated twice for viruses of different origin.
  
  
  METHODS
  All complete genome sequences of genotype B HBV were phylogenetically analyzed. Sequence divergences between different potential subgenotypes were also assessed.
  
  
  RESULTS
  Both phylogenetic and sequence divergence analyses supported the designation of subgenotypes B1, B2, B4, and B6 (from Arctic). However, sequence divergences between previously designated B3, B5, B7, B8, B9 and another B6 (from China) were mostly less than 4%. In addition, subgenotype B3 did not form a monophyly.
  
  
  CONCLUSIONS
  Current evidence failed to classify original B5, B7, B8, B9, and B6 (from China) as subgenotypes. Instead, they could be considered as a quasi-subgenotype B3 of Southeast Asian and Chinese origin. In addition, previously designated B6 (from Arctic) should be renamed as B5 for continuous numbering. This novel classification is well supported by both the phylogeny and sequence divergence of > 4%.
authors.affiliation: Guangzhou Institute of Advanced Technology, Chinese Academy of Sciences, Nansha, 511458, Guangzhou, China. wf.shi@giat.ac.cn
authors.forename: Weifeng
authors.initials: W
authors.lastname: Shi
authors.forename: Chaodong
authors.initials: C
authors.lastname: Zhu
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Carr
authors.forename: Desmond G
authors.initials: DG
authors.lastname: Higgins
authors.forename: Zhong
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D001483:Base Sequence; D016679:Genome, Viral; D005838:Genotype; D006515:Hepatitis B virus / Q000145:classification* / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny