S-gene sequences and genotype-related restriction sites in hepatitis B virus carriers in Turkey

Although hepatitis B virus (HBV) infections are a major health problem in Turkey, there is little information on the genotype distribution of the virus. In this study, HBV genotypes were determined by DNA sequencing and restriction enzyme analysis of the S gene.

The S genes of hepatitis B virus isolated from 23 chronically infected HBV-DNA-positive Turkish patients were amplified and directly sequenced. Nucleotide sequences were then aligned with reference isolates from the GenBank database and subjected to phylogenetic analysis. HBsAg subtype-specific amino acid substitutions at codons 122, 127, 134, 159, and 160 were analyzed using translated sequences. The amplified products were also subjected to restriction enzyme analysis using endonucleases Mva I, Rsa I, and Hinf I.

Phylogenetic analysis showed clustering of all samples with genotype D sequences. The mean intragroup divergence was 0.95% (range 0.00%-4.00%). All isolates were ayw2, as predicted from translated sequences. The results of the restriction enzyme analysis of the samples were consistent with the phylogenetic analysis.

Our data complement the findings that genotype D viruses are prevalent in the Turkish population. Being rapid and inexpensive, restriction enzyme analysis described in this study should be useful for large-scale epidemiological analysis of HBV infections.