Viral Hepatitis
Copyright ©2005 Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Oct 28, 2005; 11(40): 6295-6304
Published online Oct 28, 2005. doi: 10.3748/wjg.v11.i40.6295
Classifying genotype F of hepatitis B virus into F1 and F2 subtypes
Hideaki Kato, Kei Fujiwara, Robert G. Gish, Hiroshi Sakugawa, Hiroshi Yoshizawa, Fuminaka Sugauchi, Etsuro Orito, Ryuzo Ueda, Yasuhito Tanaka, Takanobu Kato, Yuzo Miyakawa, Masashi Mizokami
Hideaki Kato, Kei Fujiwara, Fuminaka Sugauchi, Etsuro Orito, Ryuzo Ueda, Department of Internal Medicine and Molecular Science, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
Yasuhito Tanaka, Takanobu Kato, Masashi Mizokami, Department of Clinical Molecular Informative Medicine, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
Robert G. Gish, Hepatology and Gastroenterology, California Pacific Medical Center, CA, United States
Hiroshi Sakugawa, First Department of Medicine, University Hospital, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan
Hiroshi Yoshizawa, Department of Epidemiology and Control of Infectious Diseases, Hiroshima University Graduate School of Biomedical Sciences, Hiroshima, Japan
Yuzo Miyakawa, Miyakawa Memorial Research Foundation, Tokyo, Japan
Author contributions: All authors contributed equally to the work.
Correspondence to: Prof. Masashi Mizokami, Department of Clinical Molecular Informative Medicine, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan. mizokami@med.nagoya-cu.ac.jp
Telephone: +81-52-853-8292 Fax: +81-52-842-0021
Received: November 8, 2004
Revised: December 21, 2004
Accepted: December 23, 2004
Published online: October 28, 2005
Abstract

AIM: To explore the propriety of providing hepatitis B virus (HBV) genotypes F and H with two distinct genotypes.

METHODS: Eleven HBV isolates of genotype F (HBV/F) were recovered from patients living in San Francisco, Japan, Panama, and Venezuela, and their full-length sequences were determined. Phylogenetic analysis was carried out among them along with HBV isolates previously reported.

RESULTS: Seven of them clustered with reported HBV/F isolates in the phylogenetic tree constructed on the entire genomic sequence. The remaining four flocked on another branch along with three HBV isolates formerly reported as genotype H. These seven HBV isolates, including the four in this study and the three reported, had a sequence divergence of 7.3-9.5% from the other HBV/F isolates, and differed by >13.7% from HBV isolates of the other six genotypes (A-E and G). Based on a marked genomic divergence, falling just short of >8% separating the seven genotypes, these seven HBV/F isolates were classified into F2 subtype and the former seven into F1 subtype provisionally. In a pairwise comparison of the S-gene sequences among the 7 HBV/F2 isolates and against 47 HBV/F1 isolates as well as 136 representing the other six genotypes (A-E and G), two clusters separated by distinct genetic distances emerged.

CONCLUSION: Based on these analyses, classifying HBV/F isolates into two subtypes (F1 and F2) would be more appropriate than providing them with two distinct genotypes (F and H).

Keywords: Genotypes; Hepatitis B virus; Phylogenetic analysis; Subtypes