Are hepatitis B virus “subgenotypes” defined accurately?

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http://www.journalofclinicalvirology.com/article/PIIS1386653210000247/abstract?r\

ss=yesJOURNAL OF CLINICAL VIROLOGYAre hepatitis B virus “subgenotypes” defined

accurately?Mahmoud Reza Pourkarimab, Samad Amini-Bavil-Olyaeec, Philippe Lemeyd,

Piet Maesa, Marc Van RanstaReceived 4 December 2009; received in revised form 14

January 2010; accepted 22 January 2010. published online 15 February

2010. Corrected ProofAbstract BackgroundRecently, several novel hepatitis B

virus (HBV) subgenotypes have been introduced that do not meet proper definition

of “subgenotypes”. In particular for HBV genotype A, such novel subgenotypes

have been reported.ObjectiveTo comprehensively reanalyse all HBV subgenotypes A,

and to propose a novel, consistent alternative for HBV classification.Study

designAll HBV full-length genome subgenotypes A1–A6 were reanalysed using

phylogenetic reconstruction and genetic distance calculation in order to study

their evolutionary relationships.ResultsPhylogenetic analysis based on the

complete genome sequence of subgenotype A strains revealed four distinct

clusters supported by high bootstrap values, whereas only the three groups A1,

A2 and A6 could be assigned as subgenotypes. Previously introduced subgenotype

A3, “tentative A4” and A5 clustered together in one main branch and were

designated as “quasi-subgenotypes”. Also genetic distances failed to classify

these three groups as definite subgenotypes. These results advocate for a new

classification of HBV genotype A into subgenotype A1, A2, “quasi-subgenotype A3”

and A4.ConclusionDetailed phylogenetic analysis of the complete genome sequences

demonstrates that some of available HBV genotype A strains may not be considered

as definite “subgenotypes”. These strains, which are mainly of African origin,

could be considered as “quasi-subgenotypes” which puts them in between the

“clade” and “subgenotype” definition. Geographical origin may have a key role in

further classification of HBV subgenotypes.a Laboratory of Clinical Virology,

Rega Institute for Medical Research, University of Leuven, Minderbroedersstraat

10, B3000 Leuven, Belgiumb Research Centre, Iranian Blood Transfusion

Organization (IBTO), Tehran, Iranc Biotechnology Department, Pasteur Institute

of Iran, 13164 Tehran, Irand Laboratory of Evolutionary Virology, Rega Institute

for Medical Research, Leuven, BelgiumCorresponding author. Tel.: +32 16 347908;

fax: +32 16 332131.PII: S1386-6532(10)00024-7doi:10.1016/j.jcv.2010.01.015© 2010

Published by Elsevier Inc.