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Open Access Research article

Subgenotype reclassification of genotype B hepatitis B virus

Weifeng Shi1*, Chaodong Zhu2, Wei Zheng234, Michael J Carr5, Desmond G Higgins6 and Zhong Zhang7*

Author Affiliations

1 Guangzhou Institute of Advanced Technology, Chinese Academy of Sciences, Nansha, 511458, Guangzhou, China

2 Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China

3 Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, China

4 Graduate University of Chinese Academy of Sciences, Beijing, 100049, China

5 National Virus Reference Laboratory, University College Dublin, Dublin, 4, Ireland

6 The Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, 4, Ireland

7 Department of Basic Medicine, Taishan Medical College, Taian, 271000, Shandong, China

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BMC Gastroenterology 2012, 12:116  doi:10.1186/1471-230X-12-116

Published: 27 August 2012

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.

Conclusion

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%.

Keywords:
Hepatitis B virus; Subgenotype; Phylogenetic analysis; Sequence divergence