Restriction fragment length polymorphism analysis and direct sequencing for determination of HBV genotypes in a Turkish population

The aim of this study was to analyze the restriction fragment length polymorphism and direct sequencing results in genotyping of hepatitis B virus from a Turkish population in a clinical virology laboratory. Serum samples of 54 chronic hepatitis B patients attending the Ege University Hospital were studied. Sequences of partial S gene PCR products were analysed and RFLP was performed. Fifty-three isolates could be identified by direct sequencing as genotype D. One sample needed to be cloned and determined as genotype D. Forty-two isolates were genotyped as D with RFLP according to published determinative patterns. Twelve isolates had undefined patterns. Eight of them suggested a mixture of isolates with different patterns and cloning of these samples confirmed the presence of heterogeneous isolates. Four isolates with undefined pattern were determined as genotype D by direct sequencing. All the studied isolates were genotype D. The results of this studied population suggest that RFLP is suitable for HBV genotyping in a routine clinical virology laboratory setting. However sequence analysis and even cloning may be needed to clarify indeterminate results.