Classifying genotype F of hepatitis B virus into F1 and F2 subtypes.
OBJECTIVE
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.


CONCLUSIONS
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).
Kato
Hideaki
H
Department of Internal Medicine and Molecular Science, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
Fujiwara
Kei
K
Gish
Robert G
RG
Sakugawa
Hiroshi
H
Yoshizawa
Hiroshi
H
Sugauchi
Fuminaka
F
Orito
Etsuro
E
Ueda
Ryuzo
R
Tanaka
Yasuhito
Y
Kato
Takanobu
T
Miyakawa
Yuzo
Y
Mizokami
Masashi
M
D000595:Amino Acid Sequence; D019143:Evolution, Molecular; D016679:Genome, Viral; D005838:Genotype; D006509:Hepatitis B / Q000821:virology*; D006515:Hepatitis B virus / Q000145:classification* / Q000235:genetics*; D006801:Humans; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA